bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of microseismic methods for identification of ground movement potential in Cemara sub-village, Sukorejo village, Gunungpati Semarang
Authors: Khumaedi  , Supriyadi  , Sugiyanto  , Pratiwi N A
Published: June 2021

Based on data of landslide from Regional Disaster Mitigation Board (BPBD), Sukorejo village is one of three urban villages in Gunungpati which has a high potential possibility for disaster, particularly landslide. One of the areas in Sukorejo Village that frequently sustains of land movement is Kampung Cemara. On April 23, 2018 in Kampung Cemara, a landslide occurred which caused detrimental damage to buildings. Several other accidents signified ground movement resulting cracks in the land surface. The high level of losses is not only induced by the magnitude of the disaster, but also due to inadequate information related to the potential for disasters and conditions in the area, that it decreases public awareness of the environment. That is the main reason for this micro seismic research. Micro seismic is a geophysical method which employ to determine the ground motion potency through the subsurface layer characteristics by calculating the value of Ground Shear Strain (GSS). The data processing is using the HVSR method. The value was ranged from 4.54 × 10−3 to 1.59 × 10−2. The result represents that Kampung Cemara is considerably potential to undergo land movements with plastic-elastic soil properties and ground motion phenomena that can effect vibration and cracks in surface land and habitation.
Discrepancy evaluation models in physics project based learning of student entrepreneurship character
Authors: Jumini S , Rusilowati A , Sutikno S , Cahyono E , Parmin P , Firdaus F
Published: June 2021

Discrepancy Evaluation Models(DEM) of Information Technology-based Project Assignment Programs in learning Physics are conducted to see whether there are gaps so that the effectiveness of the program can be continued or not. The evaluation technique is carried out by conducting interviews with supporting lecturers, observing lecture processes, and questionnaires to supporting lecturers and students. The results showed that (1) Information technology-based Project assignment program in learning Physics was carried out well with a score of 3.70. (2) The program can be done by giving students assignments by making applied physics products that can be utilized in everyday life, then presented to see the truth of the physical concept and the clarity of the product made, then students upload the video to YouTube to see the market response. (3) Information technology-based project assignment programs in physics learning provide a clear picture of how physics works in the community. The integration of Economics of Science, entrepreneurship, Nature of Science can better provide a clear picture of how Physics works in society. Thus this program can be continued by revising several existing stages.
An analysis of thinking patterns of natural sciences teacher candidate students in understanding physics phenomena using P-Prims perspective
Authors: Juliyanto E , Siswanto S
Published: June 2021

This research aimed to identify thinking patterns of natural sciences teacher candidate students in understanding physics phenomena. Results of thinking patterns could be used to determine approriate learning models and materials for students’ thinking capacity. In this research, thinking patterns were analyzed using Phenomenological Primitive (P-Prims) perspective. A random sampling technique with purposive sampling was used. The sample consisted of undergraduate students majoring in natural sciences education of Tidar University. The research method used in this research was qualitative, accompanied with The Investigation of Lived Experience with Cognitive Psychology type. Data were collected using tests and interviews. The research results show that in explaining unfamiliar physics phenomena which had never been taught before, students used 1) inductive thinking pattern, by calling back their existing, relevant knowledge and 2) deductive thinking pattern, by using synthesized general premises.
Conversion of palm oil fuel ash (POFA) into foamy geopolymer for lightweight building material application by aluminum powder addition
Authors: Kusumastuti E , Desita R , Prasetya A T , Sulistyaningsih T , Sulistyani M
Published: June 2021

Palm Oil Fuel Ash (POFA) is produced from the burning of palm oil solid waste biomass. POFA is abundant in Indonesia considering that Indonesia is one of the world’s largest producers of Crude Palm Oil (CPO) and has the largest palm oil plantation. The main content of POFA is SiO2 around 60%, Al2O3 around 3-10% and CaO around 5-15% so that POFA has the potential to be developed as aluminosilicate inorganic polymers. The high SiO2/Al2O3 ratio in POFA needs to be reduced for the formation of Si-O-Al chains in geopolymers. Therefore, two stages of research were carried out. Preliminary research was conducted to obtain optimum Solid/Liquid ratio. Aluminum powder was then added with certain variations to get a certain SiO2/Al2O3 ratio as well as a foaming agent so that the product can later be used as a porous building material. The preliminary results showed that the optimum Solid/Liquid ratio obtained was 0.83. The addition of aluminum powder was optimum at 2% w/w with a compressive strength of 5.4233 MPa, a density of 1339.2175 kg/m3, and a thermal conductivity of 0.6233 Watt/m°K. This geopolymer product can be categorized as a lightweight building material with criteria: a compressive strength of 0.5-10 MPa, densities between 600-1800 Kg/m3, and a thermal conductivity of 0.1-0.7 Watt/m°K which can be used as panels in buildings, casting walls, and ornaments in parks.
Optimization and evaluation of ionically cross-linked alginate-hpmc nanospheres for encapsulation of bromelain as antiplatelet
Authors: Gayatri A , Hudiyono S , Setiasih S
Published: June 2021

Thrombus is blood congealment process (platelet) occurred in area of vein and is useful for preventing of bleeding occurrence. The considerable amount of thrombus in blood leads to blocked arteries and angina pectoris. The partial purification of bromelain originated from pineapple core (Ananas comosus [L.] Merr) with the specific activity of 124.38 U/mg had inhibition activity to the platelet aggregation of 86.48%. On the other hand, the proteolytic activity of bromelain was relatively stable in the first 4 hours. However, the proteolytic activity significantly decreased in the next 4 hours due to the influence of gastric fluid (pH 1.2). To overcome the problem, bromelain must be encapsulated into alginate-hpmc nanospheres cross-linked by cation (CaCl2). Based on the optimization result of the swelling index and the entrapment efficiency, the nanospheres with the composition of alginate-hpmc 1: 1 and 1:2 were the optimal formula and selected to encapsulate bromelain and be characterized by PSA and SEM. Alginate-hpmc nanospheres (1:1) had a particle size of 543.7±4.2 nm. The morphology of nanospheres were almost spherical and had a smooth surface. Moreover, the particle size of alginate-hpmc nanospheres (1:2) was 515.3±26.7 nm and the SEM micrographs showed the spherical nanospheres with slightly rough surface. The swelling degree, entrapment efficiency, PSA, and SEM data will relate to suitability of the nanospheres formulation to orally deliver bromelain.
Preparation of magnetite coated humic acid (Fe3O4-HA) as malachite green dye adsorbent
Authors: Sulistyaningsih T , Ariyani S , Astuti W
Published: June 2021

Magnetite (Fe3O4) coating using humic acid (HA) to form Fe3O4/HA as malachite green dye adsorbent has been carried out. Humic acid was obtained from the isolation of peat soil from Rawa Pening, Ambarawa, Central Java, using the conventional alkaline extraction method. Synthesis of magnetite and Fe3O4/HA by coprecipitation method under alkaline conditions using NaOH. The characterization using Fourier Transform Infrared (FTIR) shows a bond between carboxylate groups in HA and Fe on magnetite, which proves that HA coating on magnetite surfaces has been successfully carried out. The characterization results using X-Ray Diffraction (XRD) showed that the coating of HA on magnetite did not change its phase shape but decreased its peak intensity. The results of characterization using a Surface Area Analyzer (SAA) showed that HA coating increased the surface area of Fe3O4. The optimum adsorption of malachite green by HA occurred at pH 3 for 60 minutes, with a concentration of 96.95 mg/L. Magnetite adsorbs optimally at pH 7 for 90 minutes and a concentration of 83.48 mg/L, while Fe3O4/HA occurs at pH 3 for 90 minutes with 104.15 mg/L.
Synthesis of polysulfone and nitrated polyeugenol based flat imprinted membrane for selective adsorption of gold
Authors: Djunaidi M C , Kusumaningtyas S A , Widodo D S , Harris A , Pardoyo
Published: June 2021

Gold (Au) is the most valuable metal compared to the other metals contained in electronic waste and adsorption is a promising method for its recovery. In this research, a flat ionic imprinted membrane (IIM) was synthesized utilizing polysulfone and nitrated polyeugenol (NPE) for the adsorption of Au. Nitrated polyeugenol was synthesized by dissolving polyeugenol in chloroform and adding it into a mixture of HNO3and H2SO4. The evidence of a successful nitration process was marked by the appearance of NO2spectra in the wavenumber area of 1533 cm−1and 1302 cm−1. The resulted NPE was then contacted with Au and analyzed by XRD. IIM synthesis was done by using polysulfone as its base, NPE-Au as its functional polymer, and polyethylene glycol (PEG) as its crosslinker. Au was then released from the membrane by immersing the membrane in thiourea solution. The membrane was characterized by SEM-EDX to examine the surface morphology. It was then used as a selective adsorbent towards Au and the adsorption results were analyzed by AAS. The results showed that the IIM is more selective towards Au compared to the non-imprinted membrane (NIM) in a selectivity test towards Cd and Cu but not in Fe.
Synergistic effect of trichloroethylene and Cu(II) on DNA-adduct 8-hydroxy deoxyguanosine (8-OHdG) formation as a biomarker of cancer risk
Authors: Nurhidayat I , Budiawan
Published: June 2021

Identification of the synergistic effect of trichloro ethylene and Cu (II) in the formation of DNA adduct 8-hydroxy deoxyguanosine (8-OHdG) as a cancer biomarker were carried out. TCE and CuCl2 were incubated with deoxyguanosine with variations in temperature (37°C and 60°C) and pH (7.4 and 8.4) for 6 hours. The 8-OHdG levels formed were analyzed using high performance liquid chromatography (HPLC). The formation of 8-OHdG from exposure to TCE seems to require high concentrations, because of its difficulty to oxidize. The addition of Cu (II) was shown to have a synergistic effect with TCE in the formation of DNA adducts which increased up to 65.8%. Temperature did not have a significant effect on DNA adduct formation. Furthermore, it is found that alkaline pH produces more DNA adducts than neutral pH.
Electrospinning of nanofibers chitosan/PVA-sodium silicate
Authors: Mahatmanti F W , Kusumastuti E , Wijayati N
Published: June 2021

Chitosan is one of the biomaterials used in making membranes using electrospinning techniques. Chitosan was chosen because it has high biocompatibility and biodegradability. Chitosan solution has high viscosity even at low concentrations therefore this polymer is very difficult to be electrospinned without other polymers addition. Mixing polymer solution is a method commonly used to provide the desired polymer solution material with combined properties for certain applications. Polyvinyl alcohol is an excellent material for making fiber. In making membranes using solvent evaporation techniques, sodium silicate added to the chitosan solution will make the chitosan-silica membrane become porous even though the effect is not significant. This article will discuss the effect of adding sodium silicate to the manufacture of chitosan-PVA-sodium silicate membranes using electrospinning method. The results showed that sodium silicate solution addition to CS/PVA polymer solutions increases the fiber diammeter percentage to be <100 nm and increased the fiber uniformity, especially in chitosan/PVA polymer mixtures with volume ratio of 2:8. The addition of sodium silicate solution to the chitosan/PVA polymer solution reduces the CS/PVA-sodium silicate fibers thermal stability but increases the CS/PVA-sodium silicate fibers hydrophilicity.
Characterization compound chemical from cocoa waste as acetic acid and phenol
Authors: Wijaya M , Wiharto M , Auliah Army
Published: June 2021

Potential Cocoa bean and derivative products consist compound of polyphenols and different potential levels of antioxidants. The greater content of polyphenols provides benefits to human health, cosmetic and food functional. Pyrolysis compounds under go decomposition into lignin, hemicellulose, and cellulose in the biomass waste that produce liquid smoke, tar, charcoal and other. The results of produce liquid smoke, tar and charcoal. Analysis of the lignin content of the cocoa pod husks from Barru District was 44.98%, cellulose was 60.03%, hemicellulose 15.54%, while the lignin content analysis of cocoa pod husks from Sidrap was 43.17%, cellulose was 43.26%, hemicellulose is 3.13%, and other is 31.3%. At a pyrolysis temperature of 514 ° C, the acetic acid content was 8.94% and the phenol content was 1.23% for the liquid smoke of the fruit skins of Barru Regency, while the acetic acid content was 4.37% and the phenol content was 9.34% for liquid smoke Sidrap Regency, From the separation of chemical compounds from the liquid smoke of cocoa pod skin in Barru Regency, it turns out that the highest content of acetic acid is 42.61% and phenol by 5.56% compared to other chemical compounds. From the separation of chemical compounds from the liquid smoke of the cocoa pods in Sidrap Regency, it turned out that the highest content of acetic acid was 42.51% and phenol by 5.54% compared to other chemical compounds.
Polymerisation behaviour of water hyacinth-based bio-oil during heating up in the presence of oxygen-containing compounds
Authors: Kadarwati S , Farida R , Kasmui  , Harjono  , Fardhyanti D S , Dewajani H
Published: June 2021

Bio-oil is susceptible to repolymerisation due to its high content of reactive oxygen-containing compounds. In this work, the polymerisation of the bio-oil produced from fast pyrolysis of water hyacinth was investigated during heating-up at various temperatures (50-95°C) in the presence of extra oxygen-containing model compounds (methanol and sucrose) with various concentration (10-50 wt%). The coke formed during the heating was quantified. The stability and reactivity of the hyacinth-based bio-oil for 48-h storage in the presence and the absence of the oxygen-containing compounds was also evaluated. This study showed that the presence of methanol in the bio-oil during heating up could suppress the repolymerisation leading to coke formation even at a higher temperature. In contrast, coke formation was severe (18.94 wt%) during the bio-oil heating up in the presence of sucrose at higher temperature (95°C). The presence of sucrose in the bio-oil could possibly promote the repolymerisation leading to coke formation. The repolymerisation possibly continued to occur during storage indicated by the increase in the viscosity, density and coke propensity of the bio-oil with added 50 wt% of sucrose compared to a negligible change in those properties of that with added methanol.
Dye-sensitized solar cells with napthol blue black as dye sensitizer
Authors: Setyawati H , Darmokoesoemo H , Murwani I K
Published: June 2021

Nowadays, fossil fuel supply is decreasing over time. Thus, people are required to look for alternative energy sources that are renewable and environmentally friendly. Dye-Sensitized Solar Cells (DSSC) is one of the promising sources to overcome those problems. In this research, a DSSC with naphthol blue-black (NBB) as dye sensitizer has been developed. In order to improve the performance of the DSSC, NBB was modified by inserting Fe to form Fe-NBB complex compound. Fe-NBB showed light harvesting characteristic through MLCT phenomenon (Metal to Ligand Charge Transfer) at 273 nm and metal-ligand bonding at 486.06 cm−1 and 316.33 cm−1. NBB and its derivatives (Fe-NBB) were applied as dye sensitizer in the DSSC. The obtained open circuit voltage, short circuit current, and efficiency for NBB were 0.218 V, 0.096 mA/cm2 and 0.0083 %, respectively. While, Fe-NBB were 0.363 V, 0.567 mA/cm2 and 0.0925%.
In-vitro Interpretation of 8-OHdG Formation as Cancer Risk Biomarker due to Malondialdehyde (MDA) and Cr (VI) Exposure through Fenton–Like Reaction
Authors: Afdila N , Budiawan
Published: June 2021

Malondialdehyde (MDA) has been widely reported as a biomarker. Endogenous genotoxic products formed from the results of lipid peroxidation and oxidative stress can bind and modify proteins, phospholipids, and DNA to form stable adducts. The increase of oxidative stress triggers how the adducts are formed—formation of adducts linked to various patterns of diseases such as cancer, cardiovascular, and neurodegenerative diseases. The research objective was to interpret 8-OHdG formation, which is triggered by oxidative damage of genetic code (2’-deoxyguanosine) exposure to chemical compounds MDA and chromium (VI). This research was done by using in-vitro studies using MDA compound and Fenton-Like reactions. The variation of reaction conditions were at 7.4 and 8.4 pH condition, 3 and 16 hours of the incubated period at the temperature of 37°C and 60°C. The reaction products were analyzed by HPLC. From this analysis, 8OHdG target compounds were found. The correlation coefficient’s value is 0.9973. The value of LOD is 11.03 μg/L, and the LOQ value is 36.77 μg/L. In vitro test to MDA compounds at 60°C incubation temperature conditions for 3 hours, and pH 7.4 produced the highest concentration of 8-OHdG, 404,09 μg/L.
Factors affecting the utilization of cow dirt as a biogas energy source in Gogik Village, West Ungaran sub-district
Authors: Heriyanti A P , Budiyono  , Purnaweni H , Dewi N K , Khusniati M
Published: June 2021

The purpose of this study is to analyze the factors that influence the use of dairy cow dung as a source of biogas energy in Gogik Village, West Ungaran District. In this study, the method used is a qualitative method by conducting in-depth interviews, observation, and documentation. The results of this study indicate that the factors that influence the use of biogas energy sources can be viewed from technical factors, social factors, and economic factors. In terms of the availability of livestock and manure produced by Gogik Village, it is feasible to implement biogas technology on a household scale. In terms of livestock raising, Gogik Village has indeed met the eligibility requirements for the implementation of biogas. The community using biogas in Gogik Village has provided a land area according to the provisions of about 20 m2. In terms of social factors, the application of biogas technology in the community must be adjusted to the habits or culture of the community groups. On the other hand, the labor required to manage biogas in Gogik Village ranges from one to two people. In terms of economic factors, the effect of biogas use on community needs has not been fully felt by the biogas user community.
Experimental and kinetic study of free fatty acid esterification derived from Ceiba pentandra seed oil with ethanol
Authors: Kusumaningtyas R D , Haifah  , Widjanarko D , Prasetiawan H , Budiono Y W P , Kusuma A D H , Anggraeni N D , Kurnita S C F
Published: June 2021

Indonesia has an abundant feedstock of Ceiba Pentandra which is very potential as a source for biodiesel production. However, it contains very high free fatty acid and can not be directly converted into biodiesel through transesterification process. One of the solution is by reacting Ceiba pentandra oil with ethanol under acid catalyst called esterification process. In this study, the operating conditions used for esterification reaction was Ceiba pentandra oil to methanol molar ratio of 1:12; with reaction time of 120 minutes. The reaction temperature was varied into 40°C, 50°C, 60°C and 70°C. The results show that, highest conversion achieved was 93.5% at reaction temperature of 70°C. Based on the experimental data, pseudo-Homogeneous model was used to model the kinetic of esterification reaction. Based on this model, the activation energy was 21.319kJ/mol and the kinetic factor was 14,264.08/minutes with R2 of 0.9675 and SSE of 0.0004.
Recovery of high purity sodium chloride from seawater bittern by precipitation-evaporation method
Authors: Jumaeri  , Mahatmanti F W , Rahayu E F , Qoyyima D , Ningrum A N K
Published: June 2021

Seawater bittern is a liquid that still exists after most of the NaCl has crystalized in the production of salt from seawater. The main components of the liquid are MgCl2 and NaCl. This study aims to recover the NaCl present in bittern through the precipitation method with NaOH and evaporation. The initial stage of this research was collection of bittern in the salt production process in a salt pond. The obtained bittern samples were then added with NaOH to precipitate the MgCl2 components as Mg(OH)2 and leave NaCl as filtrate. The precipitate and the filtrate were separated by filtration. The obtained NaCl filtrate is then evaporated to obtain high purity NaCl. The product obtained was then determined the NaCl contents by argentometric titration. NaCl crystal was characterized using FTIR spectroscopy XRD spectroscopy, and Scanning Electron Microscope (SEM). The recovery results showed that the NaCl obtained had a high purity of 98.75% w/w and yield 30,45%. The IR spectra and diffractogram obtained showed compatibility with the characteristics of the reference NaCl.
Dissemination of test instruments as product of the development research to measure the problem-solving ability of class X students by online in the pandemic period
Authors: Susilaningsih E , Nuswowati M , Aprilia N , Luthfiyah A
Published: June 2021

Assessment of online problem-solving abilities that are integrated on knowledge test questions to measure the cognitive aspects of students is very necessary during a pandemic. This study aims to disseminate test instruments, to measure students’ problem-solving abilities. This research uses descriptive quantitative method, with the design of test instrument preparation, the implementation of test, and the data analysis of test result. The research subjects were students of class X, totaling 75 students. Data collection was carried out by tests and questionnaire sheets. Data analysis used the IRT Rasch model to estimate separation item reliability, item fit, wright map, item measure, person fit, person measure and DIF items. The results showed the profile of students’ problem-solving abilities with sufficient criteria was 97% namely 73 of 75 students, with 16% classical completeness, namely 12 of 75 students. The results of the item analysis using the Rasch model showed the overall reliability of the test was 0.73, a good criterion. The results of the student response questionnaire recapitulation were as many as 95% of students gave positive responses to the developed test instruments. This test instrument is able to measure students’ problem-solving abilities and can help implement learning outcomes tests during a pandemic.
Creative skill improvement of the teacher candidates in designing learning programs through a project-based blended learning
Authors: Sumarni W , Sudarmin S , Kadarwati S
Published: June 2021

The students’ 21stcentury skills are also determined by the teachers’ 21stcentury competencies. One of them is the skill in designing learning programs. This applies as well for the teacher candidates. Improving the teacher candidates’ skill in designing learning programs is highly required and be the scope of this study. This study aims to improve the creative thinking skills of the teacher candidates in designing learning programs through a project-based blended learning (PjBL). This study was designed as an action research involving 32 teacher candidate students in a teacher education institution in Central Java, Indonesia as participants. The data collection was performed through an assessment on the process and product design of the learning programs. The data obtained were analyzed descriptively quantitatively and were categorized. An increase in the teacher candidate students’ creative thinking skills was achieved in this study with quite good and very good categories.
Determination of the water quality of Pindol river as a source of irrigation water in Bolaang Mongondow district, North Sulawesi province
Authors: Wantasen S , Luntungan J N , Lumingkewas A , Ogie T B
Published: June 2021

Pindol River is a river that is a source of irrigation water and raw water in Bolaang Mongondow Regency. The Pindol River is a source of the Lolak Dam water supply. The Lolak Dam which will irrigate rice fields covering an area of around 3,714 ha in Bolaang Mongondow Regency. The purpose of this study was to assess the water quality of the river Pindol as a source of irrigation water in terms of the value of Sodium Adsorption Ratio (SAR). The used method was field observation and laboratory analysis for river water samples. Water quality was carried out using the Composite Sampling Method in the Pindol River at two sampling points and three replications. The measured parameters were Na, Ca, Mg, as well as other chemical parameters. The measured data Na, Ca, Mg were calculating using the SAR formula. The data generated from laboratory analyzed descriptive statistics. The results showed that the concentration Na was 0.991 meq/l to 1.040 meq/l, Ca 0.281 meq/l to 0.292 meq/l, Mg 0.345 meq/l to 0.354 meq/l and Sodium Adsorption Ratio (SAR)at the Pindol River varied from 1.76 meq/l to 1.84 meq/l.
Changing user needs and motivation to visit a website through ad experience: a case study of a university website
Authors: Budiman K , Akhlis I
Published: June 2021

An organization’s website is one of its most crucial part in supporting the success of an organization. It can be used as a media campaign and acquaintanceship. Because of its importance, then user engagement is needed. User engagement is a crucial mediator in the process of persuasion involving interactive media. The user’s engagement in building the organization’s website is still low, especially on the university website. In this article, we developed a university web with a push notification to attract the user. Push notification implies not only a change in the interface between users and technology; they also imply changing user dynamics and patterns of use. This article discussing the use of push notifications can change the interest and motivation of web users. The questionnaires analyzed with User Experience Questionare+(UEQ+) conducted on respondents identified that users’ motivation to open and contribute to revisit websites increases.
Combining caesar cipher and hill cipher in the generating encryption key on the vigenere cipher algorithm
Authors: Qowi Z , Hudallah N
Published: June 2021

There is a risk in the process of exchanging information, especially text information. To reduce that risk, one of cryptographic method can be applied. That is Vigenere Cipher algorithm. But the Vigenere Cipher algorithm have a weakness. The weakness is a repetitive encryption key. It causes the chipertext to be predictable with the Babbage-Kasiski method. By combining Caesar Cipher and Hill Cipher methods in the process of generating the encryption key, its expected to cover up the weakness of the Vigenere Cipher method. The combination has the capability to hide the character appearance’s frequencies.
Development of a tracer study system for graduates of the Integrated Science Department, Universitas Negeri Semarang
Authors: Dewi N R , Listiaji P , Taufiq M , Savitri E N , Yanitama A , Herianti A P
Published: June 2021

Tracer study is a mechanism implemented by universities to track graduates to measure the relationship between educational goals and processes with the current condition of graduates. In addition, the results of the tracer study are also used as an assessment for higher education accreditation. For this reason, Department of Integrated Science, Faculty of Mathematics and Natural Sciences, Universitas Negeri Semarang has developed a website-based integrated tracer study system. The system development method used is the Waterfall Model which consists of Requirement Analysis, Design, Development, and Testing. From the results of testing conducted by information systems experts, the system being developed is very feasible both in terms of functionality and usability. The website-based online system can handle graduate data management, able to provide all information about graduates and an overview to the Departmental Council regarding the competitiveness of graduates in the world of work. It is hoped that the tracer study system that has been developed can be continued to see how the competitiveness of graduates in improving department management.
Machine-learning algorithm for demand forecasting problem
Authors: Wiyanti DT , Kharisudin I , Setiawan AB , Nugroho AK
Published: June 2021

Numerous top algorithms for time series prediction issues have been proposed. Time-series prediction has stirred up wide attention in many research fields because it is an important direction of dynamic data analysis and processing. The prediction is used in a variety of practical situations, especially for the pressing demand for forecasting future data trends based on historical information. While demand forecasting remains a challenge, developments in machine-learning have provided dramatic improvements. In this article, we investigate the feasibility and comparative analysis of Deep Learning approaches to forecasting the demand problem with implementation to a public dataset. We use comparison with RMSE performance metrics to analyze the Deep Learning performance better than other model techniques, including Random Forest, Gradient Boosted Trees, and Support Vector Machine. However, the forecasting problem is a vital need for business decision making.
Mobile learning development using augmented reality as a biology learning media
Authors: Susilo A , Hardyanto W , Martuti N K T , Purwinarko A
Published: June 2021

The use of mobile technology changes our daily lives without exception in the learning process. The use of mobile in the learning process aims to change learning and teaching methods to be innovative through visualization techniques, thereby transforming students from passive learners to active students. One of the mobile learning methods that allow us to show a given subject’s visualization is Augmented Reality (AR). The use of AR as a supporting medium in studying biology subjects. AR development uses the Luther-Sutopo Multimedia System methodology. The results of this study are mobile-based learning media to visualize biology subjects using AR.
Analysis of image watermarking with a discrete wavelet transform for digital data security
Authors: Muslim MA , Dasril Y , Khusniati M , Subhan S
Published: June 2021

One of the ways to secure digital data is image watermarking. The method for image watermarking is used with discrete wavelet transform (DWT). The problem in this article is how the performance of DWT for image watermarking. The stages of the research method are: (1) Collecting the dataset that will be used as the trial host (2) Processing data with watermarking techniques, (3) Inserting data using DWT (4) checking the quality of each method, (6) analyzing the results each method. This research has revealed the stages of data security on image watermarking with DWT and the results show that the images provided with watermarking are well secured.
Convolutional neural Network-XGBoost for accuracy enhancement of breast cancer detection
Authors: Sugiharti E , Arifudin R , Wiyanti D T , Susilo A B
Published: June 2021

Computer programs can work by imitating the human brain to make decisions that can be used in the health sector. One of them is the Convolutional Neural Network (CNN) which is combined with XGBoost as the classifier. CNN-XGBoost can be implemented for the accuracy of early detection of breast cancer. The problem is how to improve the accuracy of breast cancer detection on mammogram images. The stages of the research method: (1) Collecting the MIAS 2012 dataset, (2) Dividing data into training data and testing data. (3) preprocessing: cropping, resizing, and reshaping. (4) Data Augmentation (5) Transfer Learning (6) Classification using CNN-XGBoost (7) Testing the accuracy. Based on the research that has been carried out, the results are: (1) Obtained data on the accuracy of using CNN-XGBoost on mammogram image analysis in early detection of breast cancer. (2) Further testing is needed to improve accuracy. Further testing is needed with the use of other method or by improving the quality of mammogram images.
The factors influencing labor supply (the case for worker with non-permanent mobility in Central Java Province, Indonesia)
Authors: Subanti S , Hakim A R , Pratiwi H , Lestari E P , Hakim I M
Published: June 2021

The study about the labor supply based on worker with non-permanent mobility is very interesting, because we can find several reasons such as flexible time, family reasons, cost of living, and others. From this paper, we try to find out the factors that influence the labor supply based on worker with non-permanent mobility. This paper uses Sakernas data and the Heckman two step estimation procedure. We found that the factor from education, age, marital status, and rural-urban influence on the labor supply for worker with non-permanent mobility in Central Java Province. We suggest that the government needs to improve public transportation facilities that are feasible, accessible, safe, comfortable, and friendly to the population. In addition, when developing each mode of transportation, the government also needs to consider the physical and mental capacity aspects of transportation users, especially for commuters.
Risk analysis of five stocks indexed by LQ45 using credible value at risk and credible expected tail loss
Authors: Sulistianingsih E , Rosadi D , Abdurakhman
Published: June 2021

Value at Risk (VaR) and Expected Tail Loss (ETL) are two risk measures that are used frequently to measure the investment risk. Even though VaR can estimate maximum loss when the investor holds a single asset in a particular period and interval confidence, the investor frequently develops a portfolio of assets. This condition can create shared risk among assets in the portfolio so that there will be a chance of an asset for getting loss caused by the other assets developing the portfolio. On the other hand, there is a fact that VaR cannot provide loss information at the tail loss part so that we also need ETL that can overcome this problem. Because of that reason, this paper uses Credible Value at Risk (CredVaR) and Credible Expected Tail Loss (CredETL), which are formulated based on the Buhlman credibility concept. Both methods can estimate an investment risk that can overcome the shortcoming of VaR and ETL that do not consider the risk among assets inside the portfolio. The application of both methods was utilized to evaluate the individual risk of each asset in a portfolio comprised of five stocks in the LQ-45 Index (period of February 2019 until July 2019). The data divided into ten periods of risk analysis comprises of ten-year daily data of each stock from June 2009 to May 2019. According to the result of the analysis, it can be concluded that both methods are powerful in measuring the risk.
SEIRS model analysis for online game addiction problem of mathematics students
Authors: Anwar Azwan , Syam Rahmat , Pratama Muh.Isbar , Side Syafruddin
Published: June 2021

The purposes of this research are to build a SEIRS model on the game online addiction problem, analyze the model and do a model simulation to predict the level of online game addiction of Makassar State University students. This research is a library research, population in this study is 655 undergraduate students in mathematics with a sample of 248 student. Data collection techniques using questionnaires. Analysis of the SEIRS model of online game addiction uses a generalization matrix, while the simulation model uses the MatLab Software. The results of this study are the SEIRS mathematical model of online game addiction which is a system of differential equations. Analysis of the model gives an addiction-free equilibrium value and a stable endemic equilibrium point. The results also found a baseline value of R0 = 0.033 which showed that the level of online game addiction cases in mathematics students is not worrying, meaning that students addicted to online games did not cause other students to become addicted. The simulation results explained that 49 students were susceptible to online game addiction, 220 students began trying to play online games, 2 students were trying to get addicted to online games, and 13 students were released from online game addiction. Based on the results obtained from the number addicted to online games students the first four years increase, then reduced and constant on the eighth month.
Analysis and simulation of mathematical model for typhus disease in Makassar
Authors: Nurhaeda  , Anas S , Side S
Published: June 2021

The aims of the research is to build a mathematical model for typhus; Analyse and determine the basic reproduction number of the model; model simulations to predict the number of Typhus cases in Makassar City. This stage of the study examines the mathematical model of Typhus transmission by including food and flies as variables, which are the Susceptible-Exposed-Infected-Recovered (SEIR) model; analysed the SEIR model using the matrix generation method, then the model simulation using Maple with secondary data on the number of Typhus cases in Makassar City obtained from the Makassar Health Office. The results obtained are the SEIR model for typhus transmission by including flies and food as a variable which is an eight dimension non-linear differential equation model. This study also provides the analysis results of the SEIR model that Makassar is not worried an area Makassar for Typhus disease, this means the disease Typhus still exists in Makassar, while the calculation results of the basic reproduction number is .R0=0.137≤1, it can be concluded that the spread of typhus in Makassar is at an alarming stage, because a person suffering from typhus does not cause another person to suffer from Typhus. Model simulation results can predict the number of cases of Typhus so that early prevention can be done immediately and become the government’s attention to prevent the spread of typhus in Makassar City
The comparison of descriptive statistical parameter estimation stability using raw scores and rasch model
Authors: Susongko P
Published: June 2021

This research aims at analyzing the comparison of descriptive statistical Parameter Estimation stability using raw scores and Rasch model. The empirical data were the responses of the 12th Grade Science Students of Senior High School on Science Literary Test based on the integrated mathematics and natural sciences conducted at SMAN 2 and SMAN 3 Tegal, Central Java. This research employed a bootstrapping method assisted with SPSS version 21, while the Rasch model was assisted with R program version 3.6.3 eRm package Version 1.0.1. The parameter stability estimation was seen from its error standard and bias scores. The scores using the Rasch model was proven giving higher stability when compared to that using the raw scores in its descriptive statistical parameter estimation both from its error standard and bias aspects. Based on the error standard used, it showed that the mean and the standard deviation estimation when using the Rasch model scores was around 8 times more stable when compared to that when using the raw scores, while its median estimation were 16-18 times. Due to the use of bias measurement, it showed that the mean estimation when using the Rasch model scores was 6-10 times more stable when compared to that using the raw scores, while its median estimation and standard deviation were respectively 43-282 times and 7-10 times more stable.
The accuracy comparison of the RK-4 and RK-5 method of SEIR model for tuberculosis cases in South Sulawesi
Authors: Ramadhan N R , Minggi I , Side S
Published: June 2021

This research discusses about the accuracy of the 4th and 5th order Runge-Kutta methods (RK-4 and RK-5) as a numerical solution in the Susceptible-Exposed-Infected-Recovered (SEIR) mathematical model of Tuberculosis (TB) transmission in South Sulawesi. The data used are secondary data on the number of TB patients in South Sulawesi sourced from the South Sulawesi Health Office. The research begins by further examining the SEIR model on TB transmission, then looking for general solutions of the SEIR model with the 4th-order and 5th-order Runge-Kutta methods, parameter determination, simulation and results analysis. In this research, the movement graph is obtained from the SEIR model with real data. After analysing the numerical simulation, the accuracy of the 4th-order and 5th-order Runge-Kutta methods is compared, then the two methods are compared to observe a more accurate method. The result of this research shown that the simulation of SEIR model is accurate to predict TB cases in South Sulawesi. The Runge-Kutta method can used to observe trends in the spread of TB in South Sulawesi. The numerical simulation shown that the 5th-order more accurate than the 4th-order Runge-Kutta methods. The results of the modelling are simulated using Maple can predict the number of TB cases which can be used by the government as a consideration to prevent the spread of TB in South Sulawesi.
SEIAS-SEI model on asymptomatic and super infection malaria with imperfect vaccination
Authors: Maryam H , Abdy M , Alimuddin  , Side S
Published: June 2021

The aims of this research are to build a model of SEIAS-SEI on the spread of malaria; analysing the model; and conducting simulations to predict the number of cases of malaria in disease-free and endemic cases. This research is a theoretical study. This model uses suspected, exposed, infected and acute compartments. Analysis of the model using the matrix generation method, the data used in the simulation is an assumption data to cover the disease-free and endemic malaria cases and the model simulation using Maple. The results obtained are models of SEIRS-SEI in malaria deployments; model analysis generates equilibrium points and basic reproductive numbers to determine the status of malaria deployments in a region. Simulated results provide a sense of the difference between disease-free State and endemic is that there is a decrease in the number of infected and asymptomatic individual groups. In endemic cases, a decrease in the number of infected and asymptomatic individual groups in malaria spread takes a long time. In contrast to disease-free cases, a decline in the number of infected and asymptomatic individuals may take a short time.
Perception and understanding of Madrasah Tsanawiyah teachers on numerical literacy in mathematics learning
Authors: Sayekti I , Sukestiyarno YL , Wardono  , Dwijanto
Published: June 2021

Numerical literacy is an ability that equips students with the ability to apply the concept of numbers, calculated operation skills and the ability to interpret quantitative information However, those skills have not received much attention. Understanding of numerical literacy needs to be built, starting with teachers as leader of learning proses in schools. Therefore, this research aims to explore the perception and understanding of teachers on numerical literacy on mathematics learning. It can be used asthe basis for the development of relevant, applicative and comprehensive learning models. This research is an observational research conducted on 33 mathematics teachers in Central Java. The data was obtained during July-August through an online interview. The data was analyzed qualitatively descriptively. The results founded 24 people or 72.73% had never received literacy training, and only 5 respondents had literacy. In addition, only 48.49% of total respondents understood numeration literacy and only 21.21% of total respondents applied it in math learning. Interesting facts have been found when all teachers have used learning media from concrete examples in environments such as interpreting integers using thermometers; measuring flagpoles with Pythagoras; and classrooms and tubes to calculate surface area and volume. But respondents assumed that what they were doing was not part of numeration literacy.
Quantile regression modeling to predict extreme precipitation
Authors: Mondiana Y Q , Zairina A , Sari R K
Published: June 2021

Quantile regression is an extension of the median regression that analyzes various quantile values. This method is used to predict the relationship between the response variable (Y) and the predictor variable (X) on the conditional quantile function. Quantile regression can be used to detect extreme conditions, either extreme dry (quantile 5) or extreme wet (quantile 95). Extreme precipitation often occurs in Indonesian territory because the area is surrounded by oceans. High frequency of extreme precipitation may trigger disasters, one of which is flooding. In 2017, there were floods in Sidoarjo area with a loss of up to 2 billion. In an effort to anticipate the adverse effects of extreme precipitation, forecast information abaut extreme precipitation is needed, one of which is using quantile regression. The objectives of this research was to determine the best quantile regression model for predict extreme precitipation. The data of this study were secondary data obtained from BMKG with a data length of 30 years. Modeling of extreme precipitation in Sidoarjo area involved variables of humidity, temperature and air pressure for model 1. Whereas model 2 involved 3 variables in model 1 plus the month and month square variables. The addition of the month variable and the month quadratic variable in model 2 was based on the precipitation data plot which formed a quadratic trend. Based on the Pseudo R2value, it can be concluded that the best model to predict extreme precipitation in Sidoarjo is Model 2.
Integral mean value theorem for discontinuous function
Authors: Ovan  , Saputra A , Tasni N
Published: June 2021

This study examines the modification of the integral mean value theorem for discontinuous functions. Modification is studied by proving that a function that is not continuous at a certain and bounded interval can be integrated (finite integral) both in Rieman’s integral and Newton’s integral (integral as antiderivative). The discontinuity of the intended function, namely; f is defined on [a,b] but the value of a function and its limit are not equal at some points or infinite points and countable on (a,b), f is undefined on [a,b] at some points or infinite points and countable on (a,b) but its limit exists there. The results of this study provide a modification of the integral mean value theorem by replacing the value of f in the implication of the theorem with its limit value so that the integral mean value theorem is obtained for the non-continuous function.
Theoretical properties of the sample generalized codifference function of stable moving average process
Authors: Kharisudin I , Rosadi D
Published: June 2021

The generalized codifference function as a dependence measure for stationary processes with infinite variance has been proposed as a generalization of the autocorrelation function. In this paper we investigate the theoretical properties of estimator of generalized codifference function of stable moving average process. Some theoretical properties of the sample codifference function of moving average process for small order are discussed.