Judul: Usability Testing on the Use of Exoskeletons in Palm Oil Harvesting-loading
Abstrak: Secara umum proses panen dan muat sawit yang dilakukan oleh petani menggunakan alat dan sistem secara manual. Pada pekerjaan pemanenan kelapa sawit secara manual sangat berisiko dan dapat menyebabkan musculoskeletal disorders (MSDs). Salah satu alternatif yang dapat dilakukan untuk mengurangi risiko MSDs tersebut yaitu dengan menggunakan teknologi eksoskeleton. Penelitian ini bertujuan mengidentifikasi pengaruh sebelum dan sesudah penggunaan eksoskeleton panen-muat sawit, menguji tingkat usabilitas, dan memberikan rekomendasi perbaikan pada eksoskeleton panen-muat sawit. Eksoskeleton yang saat ini sedang dikembangkan oleh kelompok riset Biomekatronika BRIN. Penelitian ini dilakukan di PT Perkebunan Nusantara VIII Cikasungka pada Februari – Mei 2023. Penelitian dimulai dengan studi pendahuluan dengan dilakukan pengujian Gangguan Otot-Rangka Akibat Kerja (GOTRAK) menggunakan kuesioner nordic body map. Kemudian dilakukan pengujian eksoskeleton menggunakan metode usability testing, kuesioner yang digunakan yaitu Kuesioner Usefulness, Satisfaction, and Ease of use (USE) dan System Usability Scale (SUS). Hasil dari kuesioner nordic body map menunjukkan bahwa keluhan GOTRAK terbanyak terdapat pada bagian punggung bawah dengan persentase 80%. Hasil pengukuran menggunakan kuesioner USE adalah 83% yang termasuk kategori “sangat layak”. Hasil pengukuran menggunakan kuesioner SUS yaitu 73,3 yang menunjukkan bahwa eksoskeleton ini termasuk dalam kategori acceptable. Selanjutnya pada penilaian skala adjective, eksoskeleton termasuk dalam penilaian excellent. Dan pada skor nilai eksoskeleton termasuk pada peringkat C. Penelitian ini khususnya diharapkan dapat meningkatkan kesehatan kerja pada pekerjaan panen-muat sawit, dikarenakan terbukti pekerjaan tersebut dapat menyebabkan musculoskeletal disorders., In general, the process of harvesting and loading palm oil carried out by farmers uses tools and systems manually. Manual harvesting of oil palm is very risky and can lead to musculoskeletal disorders (MSDs). One alternative that can be done to reduce the risk of MSDs is to use exoskeleton technology. This study aims to identify the effects before and after the use of palm oil harvest-loading exoskeletons, test the level of reusability, and provide recommendations for improvements to palm oil harvest-loading exoskeletons. The exoskeleton is currently being developed by the BRIN Biomechatronics research group. This research was conducted at PT Perkebunan Nusantara VIII Cikasungka in February – May 2023. The study began with a preliminary study by testing Work-Induced Skeletal Muscle Disorders (GOTRAK) using a nordic body map questionnaire. Then exoskeleton testing was carried out using the usability testing method, the questionnaires used were the Usefulness, Satisfaction, and Ease of use (USE) Questionnaire and System Usability Scale (SUS). The results of the nordic body map questionnaire showed that the most GOTRAK complaints were found in the lower back with a percentage of 80%. The measurement results using the USE questionnaire were 83% which belonged to the "very feasible" category. The measurement results using the SUS questionnaire are 73.3 which shows that this exoskeleton is included in the acceptable category. Furthermore, in the adjective scale assessment, exoskeletons are included in the excellent assessment. And the exoskeleton value score is included in the C rank. This research is especially expected to improve occupational health in oil palm harvesting, because it is proven that the work can cause musculoskeletal disorders.
Keyword: Nordic Body Map, System Usability Scale, USE Questionnaire

Judul: Analisis Surface Electromyography (SEMG) Terhadap Penggunaan Exoskeleton Pada Kegiatan Panen Muat Kelapa Sawit
Abstrak: Aktivitas kerja yang dilakukan di perkebunan kelapa sawit sampai saat ini masih mengandalkan tenaga manusia. Gangguan otot rangka atau musculoskeletal disorders (MSDs) cukup umum dialami oleh para pemanen, maka dari itu pemanen membutuhkan alat bantu yang dapat mengurangi resiko kerja mereka. Penelitian ini bertujuan mengetahui pengaruh exoskeleton terhadap kerja otot pemanen saat melakukan kegiatan panen muat kelapa sawit. Hasil penelitian diharapkan dapat membantu pemanen mengurangi resiko keselamatan kerja mereka serta memberikan alat bantu untuk mengurangi resiko cedera. Otot yang diteliti pada penelitian ini adalah otot deltoid dan otot trapezius atas. Sensor electromyography (EMG) digunakan untuk mendapatkan data aktivitas kerja otot. Analisis data menggunakan analysis of variance (ANOVA) menggunakan SPSS 27.0. Uji shapiro wilk digunakan untuk mengetahui data yang terdistribusi secara normal, data dianggap normal jika p>0.05, jika data terdistribusi normal maka dilanjutkan dengan paired T-test sedangkan yang terdistribusi tidak normal dilanjutkan dengan wilcoxon signed rank test. Perbedaan beban kerja yang signifikan didapatkan di proses panen pada otot deltoid yaitu sebesar 19±9%MVE sebelum menggunakan exoskeleton dan 16±8%MVE setelah menggunakan exoskeleton. Pada proses muat tidak terlalu banyak perbedaan dikarenakan cara pemanen melakukan kegiatan muat berbeda-beda. Hal tersebut menunjukkan bahwa exoskeleton dapat mengurangi beban kerja pemanen terutama pada saat melakukan kegiatan panen., Work activities carried out in oil palm plantations until now still rely on human labor. Skeletal muscle disorders or musculoskeletal disorders (MSDs) are quite common among harvesters, therefore harvesters need tools that can reduce their work risks. This study aims to determine the influence of the exoskeleton on the work of harvester muscles when harvesting oil palm loading. The results of the study are expected to help harvesters reduce their occupational safety risks and provide tools to reduce the risk of injury. The muscles studied in this study were the deltoid muscle and the upper trapezius muscle. Electromyography (EMG) sensors are used to obtain data on muscle work activity. Data analysis using analysis of variance (ANOVA) using SPSS 27.0. The shapiro wilk test is used to determine normally distributed data, the data is considered normal if p>0.05, if the data is normally distributed then continued with the paired T-test while the abnormally distributed is continued with the Wilcoxon signed rank test. A significant difference in workload was obtained in the harvesting process in deltoid muscles, which was 19±9% MVE before using the exoskeleton and 16±8% MVE after using the exoskeleton. In the loading process, there is not too much difference because the way harvesters carry out loading activities is different. This shows that the exoskeleton can reduce the workload of harvesters, especially when harvesting.
Keyword: pemanenan kelapa sawit, musculoskeletal disorders (MSDs), exoskeleton

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.
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