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: Analysis of Work Posture Improvement with Biomechanical Methods in Teak Logging Activities
Abstrak: Kegiatan penebangan termasuk dalam kegiatan pemanenan hutan dengan risiko kerja tinggi yang disebabkan oleh beberapa faktor, diantaranya kondisi areal hutan yang tidak dapat dijangkau, kurangnya pengetahuan dan keterampilan operator, tidak seimbangnya peralatan yang digunakan dengan kemampuan operator dan mengangkat beban yang berlebihan sehingga menimbulkan rasa sakit pada tubuh operator. Kegiatan penebangan pohon jati (Tectona grandis Linn.) menggunakan chainsaw melibatkan bagian tubuh bahu, punggung dan lutut yang paling sering mengalami cedera berupa keluhan nyeri pada L5/S1 akibat menerima beban terlalu tinggi. Postur tubuh ekstrem dipilih melalui analisis Range of Motion (ROM), kemudian dilanjutkan analisis biomekanik. Postur ekstrem yang terpilih disimulasikan menggunakan software 3DSSPP 7.1.0. Analisis yang dihasilkan dari software 3DSSPP meliputi besarnya compression force dan shear force pada L5/S1, strength percent capable dan standing balance. Postur yang menghasilkan compression force >3400 N dan shear force >500 N, perlu dilakukan perhitungan Recommended Weight Limit (RWL) dan Lifting Index (LI) untuk merekomendasikan batas beban yang dapat diangkat oleh operator tanpa terjadi peningkatan risiko nyeri pada L5/S1., Logging activities are included in forest harvesting activities with high work risk caused by several factors, including the condition of the forest area that can’t be reached, lack of operator knowledge and skills, imbalance of equipment used with the operator’s ability and lifting excessive weight that cause pain in the operator body. Teak tree felling (Tectona grandis Linn.) using a chainsaw involves the shoulders, back and knees which are the most frequently injured in the form of complaints of pain in L5/S1 due to receiving too high a load. Extreme body postures were selected through Range of Motion (ROM) analysis, then followed by biomechanical analysis. The selected extreme posture is simulated using 3DSSPP 7.1.0 software. The analysis generated from 3DSSPP software includes the magnitude of compression force and shear force at L5/S1, strength percent capable and standing balance. Postures that produce compression force >3400 N and shear force >500 N, need to be calculated Recommended Weight Limit (RWL) and Lifting Index (LI) to recommend the load limit that can be lifted by the operator without increasing the risk of pain in L5/S1.
Keyword: biomechanics, felling, L5/S1, Range of Motion (ROM)

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