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"This study aimed to determine the effect of using acrylonitrile butadiene styrene in place of conventional wax material on treatment pattern removal in the investment casting process. There are three controllable process variables that can affect treatment pattern removal, which include temperature increase, holding time and the number of layers of ceramic shell that have been considered for comparison. Comparison among the effects of temperature increase, holding time and numbers of ceramic shell layers on the ceramic shell was analyzed using ANOVA. It was found that temperature increase (Tx), holding time (t) and number of layers of ceramic shell (N) contribute significantly to the length of the crack (l) on the ceramic shell. The crack in the ceramic shell’s surface was analyzed using scanning electron microscope photos. Less layers number cause the increase of crack length. The combination between temperature upraise and longer holding time cause cracking delay. The experimental is conducted by using 3 (three) variants for each of layers number, temperature and holding time. The layers number is ranging between 7-9 layers. Temperature increase from room temperature until 1300oC. The layers number variant is ranging between 180-300 seconds. It was concluded that a longer holding time will result in a more intact ceramic shell, as longer holding times yield short crack lengths."

"This study aimed to determine the effect of using acrylonitrile butadiene styrene in place of conventional wax material on treatment pattern removal in the investment casting process. There are three controllable process variables that can affect treatment pattern removal, which include temperature increase, holding time and the number of layers of ceramic shell that have been considered for comparison. Comparison among the effects of temperature increase, holding time and numbers of ceramic shell layers on the ceramic shell was analyzed using ANOVA. It was found that temperature increase (Tx), holding time (t) and number of layers of ceramic shell (N) contribute significantly to the length of the crack (l) on the ceramic shell. The crack in the ceramic shell?s surface was analyzed using scanning electron microscope photos. Less layers number cause the increase of crack length. The combination between temperature upraise and longer holding time cause cracking delay. The experimental is conducted by using 3 (three) variants for each of layers number, temperature and holding time. The layers number is ranging between 7-9 layers. Temperature increase from room temperature until 1300oC. The layers number variant is ranging between 180-300 seconds. It was concluded that a longer holding time will result in a more intact ceramic shell, as longer holding times yield short crack lengths."

"Sampel air limbah sering kali tidak dapat langsung diuji untuk parameter mikrobiologis, sehingga adanya waktu tunggu sampel. Oleh karena itu, penelitian ini akan menganalisis dinamika dan laju perubahan konsentrasi total coliform dan fecal coliform akibat adanya waktu tunggu, serta menyimulasikan perubahan tersebut agar dapat memprediksi konsentrasi awal. Pengujian sampel air limbah menggunakan metode Multi-tube Fermentation Technique (MFT). Simulasi akan menggunakan prinsip kesetimbangan massa yang diolah menggunakan “Solver” pada Microsoft Excel. Model dibangun menggunakan data dari hasil pengujian sampel di laboratorium. Hasil pengujian laboratorium menunjukkan bahwa terjadi pengurangan konsentrasi seiring bertambahnya waktu tunggu, baik bagi sampel yang diawetkan maupun tidak diawetkan. Di mana, sampel yang diawetkan mengalami pengurangan konsentrasi lebih kecil dibandingkan sampel yang tidak diawetkan. Decay rate constant konsentrasi parameter total coliform sebesar 0,24/hari untuk yang diawetkan dan sebesar 0,37/hari untuk yang tidak diawetkan, sedangkan untuk parameter fecal coliform sebesar 0,17/hari untuk yang diawetkan dan sebesar 0,48/hari untuk yang tidak diawetkan. Hasil pemodelan menggunakan nilai decay rate constant tersebut menghasilkan perkiraan nilai awal yang reliable bagi kedua parameter bila sampel diawetkan, sedangkan pada sampel yang tidak diawetkan hasil perkiraan nilai awal cukup reliable.

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Wastewater samples often cannot be tested immediately for microbiological parameters, resulting in sample holding times. Therefore, this research will analyze the dynamics and rate of change in total coliform and fecal coliform concentrations due to waiting time, and simulate these changes in order to predict the initial concentration. Wastewater samples were tested using the Multi-tube Fermentation Technique (MFT) method. The simulation will use the principle of mass balance which is processed using "Solver" in Microsoft Excel. The model was built using data from sample testing results in the laboratory. Laboratory test results show that there is a reduction in concentration as the waiting time increases, for both preserved and unpreserved samples. Where, preserved samples experience a smaller reduction in concentration than unpreserved samples. The degradation rate of total coliform concentration parameters was 0.24/day for preserved ones and 0.37/day for unpreserved ones, while for fecal coliform parameters it was 0.17/day for preserved ones and 0.48/day for preserved ones. not preserved. The modeling results using the degradation rate values ​​produce reliable initial value estimates for both parameters if the samples are preserved, whereas for unpreserved samples the initial value estimates are quite reliable."

"Emas merupakan logam mulia yang memiliki banyak keunggulan dibanding logam lainnya. Karena luasnya bidang aplikasi emas dan seiring berkembangnya teknologi, kebutuhan emas dunia terus meningkat. Peningkatan ini mendorong industri-industri untuk mengembangkan ekstraksi emas selain dari bijih hasil penambangan. Salah satu sumber yang dapat dikembangkan adalah detox sludge emas. Untuk melakukan proses pirometalurgi emas, umumnya digunakan batu bara sebagai pemasok karbon untuk proses reduksi. Namun batu bara merupakan bahan bakar tidak terbarukan yang semakin lama akan semakin menipis. Karena itu dibutuhkan agen pereduksi pengganti batu bara. Salah satu biomassa yang sudah terbukti dapat menggantikan peran batu bara adalah cangkang kelapa sawit. Kandungan fixed carbon dan volatile matter yang ada dalam cangkang kelapa sawit dapat membentuk gas pereduksi oksida logam pada terak emas. Pada penelitian ini dicari tahu temperatur operasi yang cocok dalam proses reduksi logam-logam pengotor di detox sludge emas oleh arang cangkang kelapa sawit. Proses reduksi dilakukan pada muffle furnace selama 60 menit dengan perbandingan masa detox sludge emas dan arang cangkang kelapa sawit sebesar 1:2. Temperatur operasi yang diuji adalah 800oC, 900oC, dan 1000oC. untuk menghitung recovery, detox sludge emas dikarakterisasi dengan X-ray Diffraction (XRD) dan X-ray Fluorescence (XRF) sebelum dan sesudah dilakukannya proses reduksi. Hasil penelitian ini menunjukkan temperatur optimal untuk mendapatkan recovery logam oksida tertinggi didapatkan pada suhu 800oC.

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Gold is a precious metal that has many superiorities over other metals. Due to the wide application field of gold and the development of technology, the world’s demand for gold continues to increase. This increase has encouraged industries to develop gold extraction apart from mining ore. One source that can be developed is gold detox sludge. To carry out the gold pyrometallurgical process, coal is generally used as a supplier for the reduction process. However, coal is a non-renewable fuel that will be depleted over time. So, a renewable reducing agent is needed to replace coal. Biomass is a promising option. One of the proven biomasses that can replace the role of coal is palm kernel shells. The fixed carbon content and volatile matter in the palm kernel shell can form reducing gas for the metal oxides in the gold detox sludge. This research is trying to find the suitable operation temperature for the process of reducing the metal impurities in gold detox sludge by palm kernel shells char. The reduction process is carried out in a muffle furnace for 60 minutes with a ratio of 1:2 gold detox sludge and palm kernel shells char. Operating temperatures to be tested are 800oC, 900oC, and 1000oC. To calculate recovery, gold detox sludge was characterized by X-ray Diffraction (XRD) dan X-ray Fluorescence (XRF), before and after the reduction process. The results of this study indicate that the optimal temperature for obtaining the highest metal oxide recovery is obtained at a temperature of 800oC."

"Demand for dental health care is increasing, especially in the Orthodontic field. The main objective of orthodontic treatment is to restore malocclusion conditions. Malocclusion causes aesthetics issues for the patient’s face and several discomforts like a difficulty in breathing or swallowing or speaking. If not repaired, a malocclusion could lead to other diseases, such as a greater risk of perforated teeth, gum irritation and temporomandibular disorder or pain in the lower jaw. Malocclusion can be remedied by Orthodontic Brackets. This research aim is to fabricate an orthodontic bracket that is suitable for the teeth structure of the Indonesian people. The fabrication method uses an Investment Casting process. The results show that orthodontic brackets have been successfully produced within an acceptable geometric tolerance, with the exception that surface finish quality has to be improved."

"Masalah lingkungan menjadi isu utama yang muncul seiring dengan perkembangan dunia industri. Oleh karena itu, diperkenalkan konsep remanufaktur sebagai jawaban atas permasalahan itu. Namun, aktivitas Production Planning and Control dalam remanufaktur lebih sulit untuk diterapkan sehingga perancangan produksi perusahaan pun masih banyak yang trial and error. Masalah tersebut juga menyebabkan perusahan menjadi tidak selektif dalam memilih produk untuk diremanufaktur. Dalam penelitian ini, akan dikembangkan rancangan alur produksi dan model simulasi untuk membantu PT UTR sebagai perusahaan remanufaktur alat berat dalam pemilihan produk diremanufaktur. Dari hasil penelitian akan dipilih satu produk Engine tipe besar yang akan memberikan nilai yang paling tinggi untuk perusahaan.

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The environment problem became major issue as the development of industrial sector. Because of that, remanufacturing concept has been introduced to answer that problem. However, Production Planning and Control activities is harder to implement in remanufacture field. Thus the production designs mostly use trial and error. This problem also causes the company not selective to choose the product they remanufactured. In this research, the design of production plot and simulation model will be developed to support PT UTR as the remanufacturing company in heavy equipment to choose their products to be remanufactured. The result of this research will select one product of Large Engine Type as the product that gives highest value for the company."

"Ko-pirolisis polipropilena dan minyak kelapa sawit memberikan cara pemanfaatan limbah plastik polipropilena. Penelitian ini akan meneliti reaksi ko-pirolisis di dalam reaktor tangki berpengaduk menggunakan katalis ceramic foam ZrO2/Al2O3-TiO2 untuk mengakomodasi ukuran molekul reaktan yang besar. Tujuan penelitian ini adalah untuk mendapatkan pengaruh laju pemanasan dan komposisi rasio umpan plastik polipropilena dari 0, 25, 50, 75, dan 100 % berat umpan terhadap hasil produk ko-pirolisis dan komposisi bio-oil. Produk dari ko-pirolisis akan dianalisis menggunakan metode Karl- Fischer, FTIR, GC-MS, C-NMR, dan DEPT 135 untuk menentukan kemungkinan jalur reaksi, komposisi senyawa, dan ikatan kimia yang ada di dalam bio-oil dan wax. Terdapat pengaruh laju pemanasan dan rasio umpan polipropilena terhadap jumlah produk dan senyawa kimia di dalam bio-oil. Penggunaan katalis ceramic foam ZrO2/Al2O3-TiO2 mampu meningkatkan kualitas dan yield produk akhir. Sistem pirolisis katalitik laju pemanasan tinggi tidak menunjukkan efek sinergis antara PP dan CPO dalam yield dan komponen non-oksigenat karena fraksi non-oksigenat yang rendah di bio-oil dan yield bio-oil yang rendah. Sistem pirolisis termal menunjukkan efek sinergis yang lebih tinggi antara PP dan CPO terhadap yield bio-oil yang lebih tinggi. Sistem pirolisis katalitik laju pemanasan rendah menunjukkan efek sinergis tertinggi antara PP dan CPO dalam hal jumlah fraksi non-oksigenat dan yield dari bio-oil. Analisis C-NMR dan DEPT-135 dari bio-oil menunjukkan bahwa sistem katalitik dan termal dengan laju pemanasan tinggi memiliki jumlah karbon yang terikat pada oksigen lebih tinggi dibandingkan dengan sistem katalitik laju pemanasan rendah yang menunjukkan efisiensi deoksigenasi yang lebih tinggi.

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Co-pyrolysis of polypropylene and crude palm oil gives the benefit of utilizing plastic waste of polypropylene. In the present research, co-pyrolysis reaction in a stirred tank reactor will be investigated using ZrO2/Al2O3-TiO2 ceramic foam catalyst to accommodate the large molecular size of reactants. The objectives are to obtain effects of heating rate and feed composition of polypropylene plastic from 0, 25, 50, 75, and 100 wt.% of total feed weight on yields of co-pyrolysis products and composition of bio-oil. The products were analyzed using Karl-Fischer, FTIR, GC-MS, C-NMR, and DEPT 135 to determine the possible reaction pathway, compound compositions, and chemical bonds in the bio-oil and wax. There is an effect of heating rate and feed composition on the yield and chemical compound of the product. The use of ZrO2/Al2O3-TiO2 ceramic foam catalyst improve the quality and yield of the final product. Catalytic high heating rate pyrolysis showed no synergetic effects between PP and CPO on bio-oil yield and non- oxygenates components due to low non-oxygenates fractions in bio-oil and low bio-oil yield. Thermal pyrolysis showed synergetic effects between PP and CPO on bio-oil yield. Catalytic low heating rate pyrolysis showed high synergetic effects between PP and CPO in terms of the quantity of non-oxygenates fractions in bio-oil and the bio-oil yield. C- NMR and DEPT-135 of bio-oil suggested that catalytic and thermal high heating rate system contained higher amount of carbon bound to oxygen compared to the catalytic low heating rate system which indicated higher deoxygenation efficiency."

"Indonesia merupakan salah satu negara yang memiliki deposit bijih nikel laterit terbesar di dunia. Maka dari itu tuntutan produksi nikel di Indonesia sangat tinggi. Hal itu menyebabkan jumlah smelter pengolahan feronikel semakin meningkat. Setiap satu ton feronikel hasil peleburan menghasilkan delapan ton terak feronikel. Hingga saat ini pemanfaatan terak feronikel di Indonesia masih sangat minim. Penelitian ini menjelaskan tentang peningkatan kadar besi dan magnesium dari terak feronikel dengan metode hidrometalurgi menggunakan pelindian asam sulfat (H2SO4) dengan variasi konsentrasi 0,5, 1,0, 1,5, 2,0, dan 2,5 M, variasi temperatur 32, 50, dan 90°C, serta variasi waktu 10, 20, 30, 60, dan 90 menit untuk mendapatkan kondisi paling efisien. Setelah dilakukan pelindian dilanjutkan ke proses karakterisasi ICP-OES, XRD, dan XRF. Dari karakterisasi didapatkan hasil ekstraksi Fe dan Mg terbesar yaitu 99,12% dan 99,08% pada variabel konsentrasi 2,5 M, temperatur 90°C, dan waktu 90 menit.

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Indonesia has one of the world’s largest laterite nickel ore deposits. Therefore, the demand for nickel production in Indonesia is very high. This causes the number of ferronickel processing smelters to increase. Every ton of ferronickel smelter produces eight tons of ferronickel slag. Until now, the utilization of ferronickel slag in Indonesia is still very limited. This study aimed to extract iron (Fe) and magnesium (Mg) concentration from ferronickel slag by hydrometallurgical method using sulfuric acid (H2SO4) leaching with various concentrations of 0.5, 1.0, 1.5, 2.0, and 2.5 M, temperature variations 32, 50, and 90°C, as well as time variations of 10, 20, 30, 60, and 90 minutes to get the most efficient conditions. Several characterizations including ICP-OES, XRD, and XRF were carried out in order to elucidate as well as calculate percentage of the extracted Fe and Mg. The optimum conditions for extraction of both Fe and Mg were at 90°C for 90 minutes under 2,5 M H2SO4 with the highest extraction of Fe and Mg were 99,12% and 99,08%, respectively."

"Penelitian ini bertujuan menganalisis perilaku cash holding melalui pengujian empiris variabel financial-characteristics dan kebijakan manajemen risiko pada perusahaan-perusahaan non-keuangan di Indonesia. Analisis hubungan dan pengaruh hedging sebagai instrumen manajemen risiko terhadap cash holding dilakukan menggunakan empat variasi model estimasi yang melibatkan variabel interaksi. Sebagai sampel digunakan data 127 perusahaan manufaktur yang tercatat di Bursa Efek Indonesia selama periode 2011 - 2015. Dari hasil pengujian model regresi linear berganda penelitian ini menemukan bahwa terdapat tiga variabel financial-characteristicsyang secara signifikan berpengaruh terhadap perilaku cash holding, yaitu net-working capital, cash flow, growth opportunity. Sementara variabel-variabel leverage, profitability, dan capital expenditure tidak berpengaruh signifikan. Variabel makroekonomi yang memiliki pengaruh signifikan terhadap cash holding adalah suku bunga dan pertumbuhan ekonomi. Temuan penelitian ini juga memperlihatkan indikaasi bahwa praktik-praktik bisnis yang umum dilakukan oleh perusahaan-perusahaan Indonesia yang tergabung dalam suatu kelompok usaha mempengaruhi perilaku cash holding. Variabel hedging secara individual berpengaruh negatif terhadap cash-holding. Namun, signifikansi pengaruh variabel hedging terhadap cash holding ter-reduksi oleh efek interaksi variabel leverage-hedging.

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The objective of this study is to determine the effects of financial-characteristic and risk management policy of the firm on its demand on cash. Analysis of the relation and effect of hedging as risk management instrument on cash holding is conducted using four modified estimated models, involving interaction variables. The hypothesis of corporate cash holding behavior tested using multiple regressions by publicly traded of 127 Indonesian manufacturing companies in the 2011 – 2015 periods. Results of this study suggest that net-working capital, cash flow, growth opportunity variables have significant effects on corporate cash holding, while size of the firm, leverage, profitability, and capital expenditure are not significant. Macroeconomics variables that have significant effects on corporate cash holding are interest rate and growth of gross domestic product. Finding of this study also indicates that common practices of Indonesian companies group of ownerships have impact to the degree of effects of some internal financial variables on corporate cash holding. This study also found that hedging as a risk management instrument has significant effects on corporate demand on cash, but reduces by its interaction-effect with leverage.

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"[ABSTRAKSaat ini, kebutuhan akan kesehatan gigi semakin meningkat khususnya pada bidang ortodontik. Tujuan utama dari perawatan ortodontik adalah memperbaiki kondisi maloklusi. Maloklusi menyebabkan masalah estetis pada wajah pasien serta menyebabkan kodisi tidak nyaman seperti pada saat bernapas, menelan bahkan berbicara. Jika tidak diperbaiki, maloklusi dapat menyebabkan kondisi yang lebih serius seperti resiko gigi berlubang lebih besar, gusi iritasi, pembusukan gigi, dan lain-lain. Kondisi maloklusi dapat diperbaiki dengan menggunakan perawatan braket ortodontik. Problematika yang terjadi saat ini adalah seluruh braket ortodontik yang ada di Indonesia merupakan produk impor, hal ini menyebabkan perkembangan keahlian seorang dokter gigi di Indonesia menjadi sangat tergantung dengan perkembangan desain yang terjadi di luar negeri, tanpa dapat berinovasi membuat suatu mekanisme teknik perawatan baru berdasarkan desain yang diteliti oleh dokter gigi itu sendiri. Tujuan dari penelitian ini adalah untuk memproduksi braket ortodontik serta sebagai sarana terhadap dokter gigi di Indonesia untuk dapat mengembangkan keahlian serta meneliti braket ortodontik sesuai dengan desain yang diinginkan. Produksi braket ortodontik dilakukan dengan menggunakan metode investment casting. Hasilnya menunjukan bahwa braket ortodontik telah berhasil diproduksi dengan dimensi yang berada dalam toleransi serta kualitas kekasaran permukaan yang baik. Penelitian ini merupakan tahap awal dalam studi pengembangan produksi braket ortodontik dengan metode investment casting.

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ABSTRACTCurrent, the need for dental health is increasing, especially in orthodontic field. The main purposes of orthodontic treatment is to improve the condition of malocclusion. Malocclusion causes aesthetic problems on the patient's face and causing uncomfortable conditions such as breathing, swallowing and even talking. If not corrected, malocclusion can lead to more serious conditions such as a greater risk of tooth decay, gum irritation, and others. Malocclusion can be corrected using orthodontic bracket treatment. The problems that occur nowdays is the entire orthodontic bracket in Indonesia are imported, this has led to the development of the expertise of a dentist in Indonesia to be very dependent on the development of the design which occurred abroad, without being able to create a new design examined by dentists themselves. The purpose of this research is to produce an orthodontic bracket as well as a means to dentists in Indonesia to be able to develop expertise and researching the orthodontic bracket in accordance with the desired design. Production orthodontic bracket is done by using the investment casting process. The result showed that the orthodontic bracket has successfully produced with dimensions that are within tolerance and good quality of surface roughness. This study is an early stage of the development production of orthodontic bracket by using investment casting process., Current, the need for dental health is increasing, especially in orthodontic field. The main purposes of orthodontic treatment is to improve the condition of malocclusion. Malocclusion causes aesthetic problems on the patient's face and causing uncomfortable conditions such as breathing, swallowing and even talking. If not corrected, malocclusion can lead to more serious conditions such as a greater risk of tooth decay, gum irritation, and others. Malocclusion can be corrected using orthodontic bracket treatment. The problems that occur nowdays is the entire orthodontic bracket in Indonesia are imported, this has led to the development of the expertise of a dentist in Indonesia to be very dependent on the development of the design which occurred abroad, without being able to create a new design examined by dentists themselves. The purpose of this research is to produce an orthodontic bracket as well as a means to dentists in Indonesia to be able to develop expertise and researching the orthodontic bracket in accordance with the desired design. Production orthodontic bracket is done by using the investment casting process. The result showed that the orthodontic bracket has successfully produced with dimensions that are within tolerance and good quality of surface roughness. This study is an early stage of the development production of orthodontic bracket by using investment casting process.]"