Judul: Analisis Risiko Musculoskeletal Disorders (MSDs) Operator Chainsaw pada Kegiatan Bucking Pohon Jati di Perum Perhutani KPH Madiun Divisi Regional II Jawa Timur.
Abstrak: Kegiatan pembagian batang jati diduga memiliki risiko Musculoskeletal Disorders (MSDs). Musculoskeletal Disorders merupakan penyakit atau gangguan pada otot, sendi ligamen, tendon, tulang rawan, dan pada sistem saraf. MSDs dapat disebabkan posisi tubuh tidak nyaman saat bekerja yang dilakukan secara berulang, beban kerja yang tinggi serta keadaan lingkungan dan kebiasaan hidup yang buruk. Penelitian ini dilakukan dengan menggunakan metode Rapid Entire Body Assessment (REBA) dan kuesioner keluhan MSDs Standardized Nordic Questionnaire (SNQ) yang dirasakan oleh pekerja. Berdasarkan hasil penelitian keluhan kelelahan terbesar terdapat pada bagian tangan, lengan bawah, lengan atas, pergelangan tangan, bahu, pinggang, dan betis. Seluruh elemen kerja dengan level risiko sedang sampai sangat tinggi harus dilakukan perbaikan yakni pada pembagian batang, pemotongan banir, pemotongan cabang, dan ranting serta memotong tonjolan. Hasil penelitian menyarankan agar mengurangi kegiatan penebangan dengan postur yang janggal dan penggantian chainsaw dengan bobot yang ringan.
Keyword: MSDs, Pembagian Batang, REBA

Judul: Tingkat Risiko Musculoskeletal Disorders (MSDs) Pada Penebangan Pohon Jati: Analisis REBA dan RULA
Abstrak: Penebangan pohon jati di Indonesia menggunakan chainsaw masih didominasi dengan sistem munual material handling. Kegiatan dengan sistem ini memiliki tingkat risiko musculoskeletal disorders (MSDs) yang tinggi akibat disertai beban chainsaw yang berat dan postur tubuh janggal/ekstrem pada operator. Diperlukan tindakan untuk mengurangi risiko MSDs dalam kegiatan penebangan jati dengan analisis postur kerja ekstrem yang efektif dan aksi ergonomi. Penilaian risiko MSDs dilakukan menggunakan instrumen Rapid Entire Body Assessment (REBA) dan Rapid Upper Limb Assessment (RULA). Hasil analisis postur kerja menggunakan metode REBA memiliki tingkat risiko MSDs yang bervariasi daripada RULA yang secara keseluruhan kegiatan penebangan jati berisiko ergonomi sangat tinggi. Sehingga penilaian postur kerja pada kegiatan penebangan pohon jati, instrumen RULA lebih disarankan karena sensitivitas yang dimiliki lebih tinggi daripada REBA. Adapun aksi ergonomi untuk mengurangi risiko pada postur kerja operator chainsaw berupa perbaikan postur dengan menghindari postur membungkuk dan mengganti dengan postur berlutut, menggunakan alat chainsaw dengan beban yang lebih ringan dan pemeliharaan alat yang baik, serta adanya penambahan durasi istirahat operator untuk relaksasi otot tubuh., The felling of teak trees in Indonesia using chainsaws is still dominated by the munual material handling system. Activities with this system have a high level of risk of musculoskeletal disorders (MSDs) due to heavy chainsaw loads and awkward/extreme postures for operators. Action is needed to reduce the risk of MSDs in teak felling activities by analysing effective extreme work postures and ergonomic actions. MSDs risk assessment is carried out using Rapid Entire Body Assessment (REBA) and Rapid Upper Limb Assessment (RULA) instruments. The results of work posture analysis using the REBA method have varying levels of MSDs risk than RULA, which overall teak logging activities are very high ergonomic risk. So that the assessment of work postures in teak logging activities, the RULA instrument is more recommended because of its higher sensitivity than REBA. As for ergonomic actions to reduce the risk in the work posture of chainsaw operators in the form of posture improvement by avoiding slouching postures and replacing them with kneeling postures, using chainsaw tools with lighter loads and good tool maintenance, and increasing the duration of operator breaks for relaxation of body muscles.
Keyword: MSDs, REBA, RULA, teak felling, work posture

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
Keyword: