Judul: An analysis of work posture with biomechanical method  in cutting teak tree delimbing activities
Abstrak: Kegiatan pemotongan cabang merupakan kegiatan yang mengkombinasikan gerakan kerja yang sulit dan kerja otot yang keras dalam pengoperasikan chainsaw sehingga memberikan postur tubuh ekstrim yang menyebabkan resiko cedera pada otot. Tujuan penelitian ini untuk mengidentifikasi level risiko menggunakan Range of Motion (ROM), menghitung gaya tekan (compression force) pada L5/S1 menggunakan analisis biomekanik dan memberikan perbaikan postur kerja berdasarkan perhitungan RWL dan LI. Postur kerja pada kegiatan pemotongan cabang yang memiliki risiko tinggi terjadinya cedera adalah pada postur membungkuk dan postur berdiri tegak mengangkat chainsaw setinggi bahu. Postur membungkuk memiliki nilai gaya tekan pada L5/S1 melebihi batas AL atau ≥ 3400 N. Sedangkan postur berdiri tegak mengangkat chainsaw setinggi bahu memiliki nilai gaya tekan yang tidak melebihi batas AL yang artinya masih tergolong aman dalam sudut pandang gaya tekan. Namun, pada perhitungan RWL dan LI, postur kerja berdiri tegak mengangkat chainsaw setinggi bahu merupakan postur yang tergolong berbahaya dan menyebabkan cedera serius. Nilai RWL mengangkat chainsaw setinggi bahu adalah 4,78 kg dan LI sebesar 3,66 , nilai tersebut menunjukkan perlu adanya perbaikan kerja., Delimbing activity is an activity that combines difficult work movements and hard muscle work in chainsaw operation so it provides an extreme body posture that causes the risk of muscle injury. The purpose of this study was to identify the level of risk using Range of Motion (ROM), to calculate the compression force at L5/S1 using biomechanical analysis and to provide improvements in working posture based on RWL and LI calculations. The working posture in delimbing activities that has a high risk of injury is the bent posture and the upright posture lifting the chainsaw to shoulder height. The bending posture has a compressive force value at L5/S1 exceeding the AL limit or 3400 N. While the upright posture lifting the chainsaw to shoulder height has a compressive force value that does not exceed the AL limit, which means it is still relatively safe from the point of view of the compressive force. However, in the RWL and LI calculations, the working posture of standing upright lifting the chainsaw to shoulder height is a posture that is classified as dangerous and causes serious injury. The RWL value for lifting the chainsaw to shoulder height is 4.78 kg and the LI is 3.66. These values indicate the need for work improvement.
Keyword: biomechanics, delimbing, L5/S1, ROM, RWL

Judul: Risk of Work Posture of Teak Delimbing Operator Using  Chainsaw with REBA and RULA Analysis Methods
Abstrak: Pembersihan batang jati di Indonesia masih dilakukan secara motor-manual menggunakan chainsaw yang berat. Beban chainsaw yang berat dan kondisi batang yang dibersihkan dapat memicu terjadinya postur kerja ekstrem. Diperlukan analisis terhadap berbagai macam postur kerja ekstrem pada pembersihan batang jati untuk mengetahui risikonya bagi kesehatan otot operator chainsaw. Postur kerja ekstrem didapatkan dari hasil analisis Range of Motion yang kemudian akan dianalisis risiko postur kerja statisnya menggunakan metode Rapid Entire Body Assessment (REBA) dan Rapid Upper Limb Assessment (RULA). Postur kerja ekstrem yang dianalisis menggunakan metode REBA menunjukkan risiko kesehatan otot sedang hingga tinggi. Hasil analisis menggunakan metode RULA menunjukkan hampir seluruh postur yang dianalisis berisiko tinggi. Postur berdiri tegak dengan letak chainsaw yang tidak terlalu tinggi terbukti memiliki risiko yang lebih rendah. Upaya yang dapat dilakukan untuk mengurangi risiko pada postur kerja operator chainsaw dapat berupa perbaikan postur dengan menghindari postur membungkuk, pengurangan beban angkat dengan menggunakan chainsaw yang lebih ringan, dan penambahan waktu istirahat bagi otot tubuh., Teak delimbing in Indonesia is still done manually using a heavy chainsaw. Heavy chainsaw loads and the condition of the trunk being cleaned can lead to extreme work postures. An analysis of various extreme work postures in teak delimbing is needed to determine the risks to the health of the chainsaw operator's muscles. Extreme work postures are obtained from the Range of Motion analysis which will then be analyzed for the risk of static work postures using Rapid Entire Body Assessment (REBA) and Rapid Upper Limb Assessment (RULA) methods. The extreme work postures analyzed using the REBA method indicate a moderate to high muscle health risk. The results of the analysis using the RULA method show that almost all of the analyzed postures are high risk. An upright posture with a chainsaw that is not too high has been shown to have a lower risk. Efforts that can be made to reduce the risk in the chainsaw operator's work posture can be in the form of improving posture by avoiding a slouching posture, reducing lifting loads by using lighter chainsaw, and increasing rest time for the body's muscles.
Keyword: Analisis, postur kerja, REBA, risiko, RULA

Judul: Hybrid solar cells of ZnO nanoparticles/chlorophyll was modified metal ions (Zn2+ and Cu2+ )
Abstrak: Zinc Oxide (ZnO) is a n-type semiconductor with a wide the energy band (Band Gap) is 3.37 eV at room temperature and 3.34 eV at low temperature with a large exiton binding energy is 60 meV. ZnO has been synthesized by hydrothermal method, resulting in a decrease in particle size over the duration of the hydrothermal changes. Crystallographic structure of ZnO were characterized using XRD, has shown the characteristic pattern of a hexagonal wurtzite structure, the crystallite size increases to changes in particle size. Changes in particle size has also led to a change in the absorption peak of ZnO as has been demonstrated posted under test using the optical properties of UV-Vis spectrophotometer. Changes of this uptake has also led to changes in the energy band gap, which increases its band gap energy of the particle size. In electronic applications, especially in solar cells. Chlorophyll is considered less effective, because of their very nature are easily degraded as a result of several reactions which are acid, lighting and temperature. The results of the stability test using a halogen lamp 34 W/m2 for 5 hours, that the substitution of chlorophyll with metal ions Zn2+ and Cu2+ has been shown to form more stable than natural chlorophyll. The characterization of the optical properties, the combination of ZnO / chlorophyll in the form of hybrid films has led to a shift in the absorption region of ZnO becomes more widely from the UV to Visible. ZnO/chlorophyll has absorption range of 350-515 nm, ZnO / Zn-feofitin 332-401 nm and 332-632 nm for Cu-feofitin. The combination of ZnO/chlorophyll and CuSCN as a solid electrolite in hybrid solar cell, a modified chlorophyll with metal ions Zn2+ and Cu2+ has been shown to form a more stable I-V curve. It is characterized by its fill factor value greater than natural chlorophyll. Nevertheless, solar cells with natural chlorophyll has been able to produce higher efficiency values of chlorophyll were substituted.
Keyword: Hydrothermal, ZnO/Chlorophyll modified, Hybrid Solar Cell