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"Layer manufacturing methods have been used widely in many manufacturing industries for building a three dimensional object (3D), however, those methods still need improvement. One example of the improvement is process parameters of the second generation Glue Extruded Deposition (GED-2) developed by the author at the Department of Mechanical and Industrial Engineering UGM. A Surface Response method has been applied to investigate the optimum setting of process parameters include: scanning speed (V), scanning space (s), gap between working table surface and nozzle (h), and heating temperature of material (T). While, a model as a 3D object was a cube and the material for building the object was Ethylene Vinyl-Acetate (EVA) in the form of cylinder with 10 mm diameter and 100 mm long. The results show that the best dimension as recommended by surface response method were 0.8749 mm wide and 0.7035 mm thick. Other reccomendations were excess dimension due to scanning was 0.37 mm long and the best setting of process parameters were h = 0,64 mm, V = 80 mm/minute and T = 94°C."

"Abstrak Metode Response Surface terdiri dari pemodelan statistik dan optomisasi motode response surface umumnya digunakan untuk mengoptimalkan suatu proses atau respon . Proses (respon) tersebut dipengaruhi oleh beberapa variabel input (faktor) untuk menentukan variabel -variabel input yang mempengaruhi respon, ..."

"Benzoin essential oil adalah oleoresin bernilai tinggi yang berasal dari getah kering pohon Styrax benzoin. Di Indonesia, getah kering pohon ini diperdagangkan dengan tiga varian berbeda, yaitu: kemenyan putih, kemenyan tahir madu dan kemenyan hitam super. Sampai saat ini belum ada publikasi tentang karakteristik yang meliputi sifat fisika-kimia ketiga jenis varian essential oil dari ketiga varian kemenyan. Kondisi optimum proses ektraksi essential oil dari ketiga varian kemenyan ini belum diketahui. Pada penelitian ini, benzoin essential oil telah diproduksi menggunakan metode ekstraksi refluks etanol. Dalam studi optimasi, diselidiki pengaruh parameter proses ekstraksi yang meliputi rasio bahan mentah terhadap etanol dan waktu ekstraksi. Dengan bantuan analisis regresi menggunakan Response Surface Methodology (RSM), hasilnya menyarankan bahwa kondisi ekstraksi yang optimal, yaitu: perbandingan bahan mentah terhadap etanol 1:4,80 dan waktu ekstraksi 4,134 jam untuk kemenyan putih, 1:5,13 dan 3,80 jam untuk kemenyan tahir madu serta 1:4,93 dan 4,09 jam untuk kemenyan hitam super. Essential oil yang dihasilkan dari ketiga varian kemenyan pada kondisi tersebut secara berturut-turut adalah 45,30 g; 47,76 g; dan 45,42 g. Penelitian lebih lanjut tentang kualitas ekstrak menggunakan GCMS menghasilkan empat senyawa kimia utama sebagai komponen terbesar yang menyusun Styrax benzoin, yaitu (Z)-Cinnamic acid, n-Hexadecanoic acid, cis- Vaccenic acid dan Cinnamyl cinnamate. Uji antioksidan menunjukkan bahwa kemenyan hitam super memiliki aktivitas antioksidan tertinggi dengan nilai IC50 sebesar 90,0348; diikuti kemenyan putih dan kemenyan tahir madu dengan nilai 114,0560 dan 123,8628. Informasi yang dihasilkan dari penelitian ini berguna untuk pengembangan industri essential oil, terutama yang berasal dari resin kemenyan dan turunannya.

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Benzoin essential oil is a high-value oleoresin derived from the dried sap of the Styrax benzoin tree. In Indonesia, the dried sap of this tree is traded with three different variants, namely: white incense, honey clean incense and super black incense. Until now there have been no publications on the characteristics that include the physico-chemical properties of the three types of essential oil variants from the three variants of incense. The optimum condition for extracting essential oils from the three variants of incense is unknown. In this study, benzoin essential oil was produced using ethanol reflux extraction method.

In the optimization study, investigated the effect of the parameters of the extraction process which included the ratio of raw materials to ethanol and extraction time. With the help of regression analysis using Response Surface Methodology (RSM), the results suggest that the optimal extraction conditions, namely: the ratio of raw materials to ethanol 1: 4,80 and extraction time 4,134 hours for white incense, 1: 5,13 and 3,80 hours for honey clean incense and 1: 4.93 and 4.09 hours for super black incense. Essential oil produced from the three variants of incense in these conditions is 45.30 g; 47.76 g; and 45.42 g.

Further research on the quality of extracts using GCMS produced four main chemical compounds as the largest component that composes Styrax benzoin, namely (Z) -Cinnamic acid, n- Hexadecanoic acid, cis-Vaccenic acid and Cinnamyl cinnamate. Antioxidant tests showed that super black incense had the highest antioxidant activity with an IC50 value of 90.0348; followed by white incense and honey clean incense with values of 114.0560 and 123.8628. Information generated from this research is useful for the development of the essential oil industry, especially those derived from incense resin and its derivatives."

"Pembangkit Pembangkit Listrik Tenaga Mesin Gas (PLTMG) Balai Punggut-Duri memiliki peran penting dalam penyediaan energi eputus di wilayah Sumatera Tengah. Namun, karena fleksibilitas operasinya, terdapat variasi yang signifikan dalam efisiensi dan emisi antar unit yang beroperasi, khususnya pada unit 4-7. Penelitian ini bertujuan untuk mengoptimalkan operasi unit-unit tersebut dengan mempertimbangkan faktor-faktor penting seperti efisiensi, NPHR (Net Plant Heat Rate), dan emisi Nox. Untuk mencapai tujuan ini, digunakan metode Response Surface Methodology (RSM) untuk memodelkan hubungan antara variasi beban (10 MW, 12 MW dan 14 MW) dan faktor (0,99, 0,95 dan 0,90) daya dengan kinerja pembangki listrik. Metode ini memungkinkan analisis yang lebih mendalam terkait dengan pengaruh variasi parameter operasi terhadap efisiensi dan emisi yang dihasilkan. Setelah pemodelan dilakukan, metode Multi-Objective Genetic Algorithm (MOGA) diterapkan untuk mencari eputu optimal yang dapat menyeimbangkan efisiensi, NPHR, dan emisi Nox secara simultan. Hasil penelitian menunjukkan bahwa optimasi dengan pendekatan MOGA-RSM berhasil mengidentifikasi pola start-up yang optimal untuk masing-masing unit. Urutan prioritas start-up berdasarkan efisiensi, NPHR, dan emisi Nox yang optimal adalah unit 6, unit 7, unit 4, dan unit 5. Penelitian ini memberikan kontribusi baru dalam optimasi operasi PLTMG Duri dengan mengintegrasikan metode RSM dan MOGA. Pendekatan ini belum banyak diterapkan dalam studi sebelumnya dan dapat menjadi referensi dalam meningkatkan efisiensi operasional pembangkit listrik, serta mengurangi dampak lingkungan, khususnya dalam hal pengurangan emisi Nox. Pola start-up yang dihasilkan diharapkan dapat mendukung operasional PLTMG Duri yang lebih efisien dan ramah lingkungan, serta memberikan dasar bagi pengelolaan sumber daya energi yang lebih berkelanjutan.

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The Balai Punggut-Duri Gas Turbine Power Plant (PLTMG) plays a significant role in meeting the electricity demand in Central Sumatra. However, due to its flexible operation, there are significant variations in efficiency and emissions across the units, especially in units 4-7. This study aims to optimize the operation of these units by considering key factors such as efficiency, NPHR (Net Plant Heat Rate), and Nox emissions. To achieve this, the Response Surface Methodology (RSM) is employed to model the relationship between load variation (10 MW, 12 MW and 14 MW) and power factor (0,99, 0,95 and 0,90) with plant performance. This method enables a deeper analysis of the effects of operational parameters on efficiency and emissions. Following the eputusan process, the Multi-Objective Genetic Algorithm (MOGA) is applied to find an optimal solution that simultaneously balances efficiency, NPHR, and Nox emissions. The results indicate that optimization using the MOGA-RSM approach successfully identifies the optimal start-up pattern for each unit. The prioritized start-up order based on efficiency, NPHR, and Nox emissions is unit 6, unit 7, unit 4, and unit 5. This research contributes new insights into optimizing PLTMG Duri operations by integrating the RSM and MOGA methods. This approach has not been widely applied in previous studies and can serve as a reference for improving the operational efficiency of power plants while reducing environmental impacts, particularly in terms of Nox emission reduction. The recommended start-up patterns are expected to support more efficient and environmentally friendly operations of PLTMG Duri, providing a foundation for the more sustainable management of energy resources."