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Journal of Engineering and Technological Sciences
Published by Institut Teknologi Bandung
ISSN : 23375779     EISSN : 23385502     DOI : -
Core Subject : Engineering,
Engineering
Journal of Engineering and Technological Sciences welcomes full research articles in the area of Engineering Sciences from the following subject areas: Aerospace Engineering, Biotechnology, Chemical Engineering, Civil Engineering, Electrical Engineering, Engineering Physics, Environmental Engineering, Industrial Engineering, Information Engineering, Mechanical Engineering, Material Science and Engineering, Manufacturing Processes, Microelectronics, Mining Engineering, Petroleum Engineering, and other application of physical, biological, chemical and mathematical sciences in engineering. Authors are invited to submit articles that have not been published previously and are not under consideration elsewhere. Starting from Vol. 35, No. 1, 2003, full articles published are available online at http://journal.itb.ac.id, and indexed by Scopus, Index Copernicus, Google Scholar, DOAJ, GetCITED, NewJour, Open J-Gate, The Elektronische Zeitschriftenbibliothek EZB by University Library of Regensburg, EBSCO Open Science Directory, Ei Compendex, Chemical Abstract Service (CAS) and Zurich Open Repository and Archive Journal Database. Publication History Formerly known as: ITB Journal of Engineering Science (2007 – 2012) Proceedings ITB on Engineering Science (2003 - 2007) Proceedings ITB (1961 - 2002)
Arjuna Subject : -
Articles 1,267 Documents
 81   82   83   84   85 
Effects of Netbook and Tablet Usage Postures on the Development of Fatigue, Discomfort and Pain Yassierli Yassierli; Anita Juraida
Journal of Engineering and Technological Sciences Vol. 48 No. 3 (2016)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2016.48.3.1

Abstract

The number of people using online tablets in public places has increased dramatically. Their postures are dominantly characterized by non-neutral and awkward positions that in the long term may lead to a higher risk of musculoskeletal disorders. The purpose of this study was to investigate the effects of tablet compared to laptop (i.e. netbook) usage postures on the development of fatigue, discomfort and pain. A total of 12 participants accomplished email typing tasks for 2 hours with four different usage configurations: 1) Netbook-on-table, 2) Netbook-on-lap, 3) Tablet-on-table, and 4) Tablet-on-lap. Changes in fatigue, discomfort, and pain were monitored based on pinch grip strength (tip pinch, key pinch, and palmar pinch), rating of perceived discomfort, and Phalen's & Reverse Phalen's tests, respectively. The results indicated that the effect of portable device placement was significant (p < 0.05), with varied effects across measurements. No effect of portable computer type was found. The interactive effect of portable computer type and placement was only significant for right tip pinch (p < 0.05). The findings of this study can hopefully be used to increase the awareness of tablet users about associated fatigue, discomfort and pain while using a tablet in public places that may lead to a higher risk of musculoskeletal disorders.
Characteristics of Rainfall-Discharge and Water Quality at Limboto Lake, Gorontalo, Indonesia Luki Subehi; Hendro Wibowo; Kwansue Jung
Journal of Engineering and Technological Sciences Vol. 48 No. 3 (2016)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2016.48.3.4

Abstract

Problems of high turbidity, sedimentation, water pollution and siltation occur at Limboto Lake, Gorontalo, Indonesia. The objective of this study was to analyze the rainfall-discharge relationship and its implications for water quality conditions. Secchi disk (water transparency), chlorophyll-a (chl-a), and total organic matter (TOM) were measured in May 2012, September 2012 and March 2013 at three sites of the lake (L-1, L-2 and L-3) to observe the impacts on the surrounding catchment. Based on representative stations for rainfall data from 2004 to 2013, monthly averages of rainfall in March-May (166.7 mm) and September (76.4 mm) were used to represent the wet and dry period, respectively. Moreover, sediment traps at these three sites were installed in September 2012. Based on the analysis it is suggested that rainfall magnitude and land use change at the Alopohu River catchment influenced the amount of materials flowing into the lake, degrading the water quality. Specifically, the higher average rainfall in May (184.5 mm) gave a higher average total sediment load (4.41 g/L/day). In addition, water transparency decreased with increasing chl-a. This indicates that the concentrations of sediment and nutrients, reflected by the high amount of chl-a, influenced the water quality conditions.
Molecular Weight and Structural Properties of Biodegradable PLA Synthesized with Different Catalysts by Direct Melt Polycondensation Hyung Woo Lee; Rizki Insyani; Daniel Prasetyo; Hermawan Prajitno; Johnner P. Sitompul
Journal of Engineering and Technological Sciences Vol. 47 No. 4 (2015)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2015.47.4.2

Abstract

Production of biodegradable polylactic acid  (PLA)  from biomassbased lactic acid is widely studied for substituting petro-based plastics  or polymers. This study investigated PLA production from commercial lactic acid in a batch reactor by applying a direct melt polycondensation method with two kinds of catalyst,  γ-aluminium(III)  oxide  (γ-Al2O3) or  zinc oxide (ZnO),  in reduced pressure. The molecular weight of the synthesized PLA was determined by capillary viscometry and its structural properties were analyzed by functional group analysis using FT-IR. The yields of polymer production with respect to the theoretical conversion were 47% for γ-Al2O3 and 35% for ZnO. However, the PLA from ZnO had a higher molecular weight (150,600 g/mol) than that from γ-Al2O3 (81,400 g/mol). The IR spectra of the synthesized PLA from both catalysts using polycondensation show the same behavior of absorption peaks at wave numbers from 4,500 cm-1 to 500 cm-1, whereas the PLA produced by two other polymerization methods "“ polycondensation and ring opening polymerization "“showed a significant difference in % transmittance intensity pattern as well as peak area absorption at a wave number of 3,500 cm-1 as "“OH vibration peak and at 1,750 cm-1 as "“C=O carbonyl vibrational peak.
Kinetics of Palm Oil Transesterification Using Double Promoted Catalyst CaO/KI/γ- Al2O3 Nyoman Puspa Asri; Kusno Budikarjono; Suprapto Suprapto; Achmad Roesyadi
Journal of Engineering and Technological Sciences Vol. 47 No. 4 (2015)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2015.47.4.1

Abstract

Double promoted catalyst (CaO/KI/γ-Al2O3) was used as the catalyst for transesterification of palm oil into biodiesel. The experiment was carried out in a batch reactor consisting  of a three-neck glass flask (500 ml capacity) equipped with a reflux condenser, thermometer and magnetic stirrer. Kinetic study was  carried out with methanol under reflux conditions  at different temperatures (35-75°C) and different times of reaction (1-7 hours). The effects of temperature and time of the reaction on the conversion of palm oil into biodiesel and reaction rate constants were investigated. The results showed that the conversion and rate constants of reaction increased with the increasing of the reaction temperature. The highest conversion of 97% was obtained at 65°C and 5 hours  of reaction time. Meanwhile, the activation energy and the frequency factor were 15.47 kJ/mol and 1.22.102, respectively.
Production of Methyl Laurate from Coconut Cream through Fractionation of Methyl Ester Johnner P. Sitompul; A.N. Istyami; R. Muhtadi; H.W. Lee; H. Rahman
Journal of Engineering and Technological Sciences Vol. 47 No. 5 (2015)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2015.47.5.1

Abstract

This paper concerns the production of methyl laurate from coconut cream through fractionation of methyl esters. Coconut oil was produced by wet processing of coconut cream. The esters were prepared by reacting coconut oil and methanol using homogeneous catalyst KOH in a batch reactor, followed by fractionation of fatty acid methyl esters (FAME) at various reduced pressures applying differential batch vacuum distillation. Experimental data were compared with simulation of a batch distillation employing the simple Raoult's model and modified Raoult's model of phase equilibria. Activity coefficients (γi) were determined by optimization to refine the models. The modified Rault's model with activity coefficients gave better agreement with the experimental data, giving the value of γi between 0,56-0,73. For a given boiling temperature, lower operating pressure produced higher purity of C10 and C12 FAME for respective distillates.
Alkaline Treatment of Oil Palm Frond Fibers by Using Extract of Oil Palm EFB Ash for Better Adhesion toward Polymeric Matrix Warman Fatra; Randi Sanjaya; Zulfansyah Zulfansyah; Hari Rionaldo; Zuchra Helwani
Journal of Engineering and Technological Sciences Vol. 47 No. 5 (2015)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2015.47.5.3

Abstract

In Indonesia, 187 million tons of biomass were produced from 8.11 million ha of oil palm plantation in 2009. This massive amount of biomass mainly consists of oil palm fronds (OPF) and oil palm empty fruit bunches (EFB), which are normally categorized as waste. The properties of OPF fibers compared to those of synthetic fibers, such as low density, low cost, less abrasion of equipment, and safer production, makes them an attractive reinforcement for composite materials. In this work, the utilization of oil palm empty fruit bunch ash for OPF fiber-polyester resin composite and the effect of process conditions were studied. Water absorption, tensile and flexural strength were used to characterize the effects of alkaline treatment on modified OPF fibers in polyester resin. The investigation focused on the effect of alkaline treatment time. Treatment temperature and liquid to solid ratio were analyzed using Response Surface Method-Central Composite Design (RSM-CCD). The highest tensile strength (44.87 MPa) was achieved at 12 hours soaking time, at 40°C treatment temperature and 5:1 water to ash ratio. The highest flexural strength (120.50 MPa) was obtained at 1.3 hours soaking time, 4 dissolving ratio and 35°C treatment temperature. The lowest water absorption of composite (3.00%) was achieved at the longest soaking time (14.7 hours), 4 dissolving ratio and 35°C treatment temperature. Variance of soaking time, dissolving ratio and temperature in the alkaline treatment process using extract of oil palm empty fruit bunch ash significantly affected the mechanical and physical properties of the oil palm frond fibers reinforced composite.
Enhancement of Chlorella vulgaris Biomass Cultivated in POME Medium as Biofuel Feedstock under Mixotrophic Conditions M.M. Azimatun Nur; H. Hadiyanto
Journal of Engineering and Technological Sciences Vol. 47 No. 5 (2015)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2015.47.5.2

Abstract

Microalgae cultivated in mixotrophic conditions have received significant attention as a suitable source of biofuel feedstock, based on their high biomass and lipid productivity. POME is one of the wastewaters generated from palm oil mills, containing important nutrients that could be suitable for mixotrophic microalgae growth. The aim of this research was to identify the growth of Chlorella vulgaris cultured in POME medium under mixotrophic conditions in relation to a variety of organic carbon sources added to the POME mixture. The research was conducted with 3 different carbon sources (D-glucose, crude glycerol and NaHCO3) in 40% POME, monitored over 6 days, under an illumination of 3000 lux, and with pH = 7. The biomass was harvested using an autoflocculation method and dry biomass was extracted using an ultrasound method in order to obtain the lipid content. The results show that C. vulgaris using D-glucose as carbon source gained a lipid productivity of 195 mg/l/d.
Sulfur Removal in Bio-Briquette Combustion Using Seashell Waste Adsorbent at Low Temperature Mahidin Mahidin; Asri Gani; Abrar Muslim; Husni Husin; M. Reza Hani; Muhammad Syukur; Hamdani Hamdani; Khairil Khairil; Samsul Rizal
Journal of Engineering and Technological Sciences Vol. 48 No. 4 (2016)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2016.48.4.8

Abstract

Presently, biomass is mostly utilized as co-fuel in coal combustion in view of energy diversification and emission reduction. However, since the coal content of bio-briquettes is high (up to 80% in this study), gas emissions such as those of SOx still occur. Therefore, the introduction of SO2adsorbent is common in coal briquette or bio-briquette combustion. A calcium-based material is usually used for this goal. The aim of this study was to observe the effects of desulfurization temperature and Ca/S ratio (Ca = calcium content in adsorbent; S = sulfur content in coal and biomass) on desulfurization efficiency and kinetics. The ratio of coal to biomass (palm kernel shell/PKS) was fixed at 90:10 (wt/wt) and the ratios of Ca to S were varied at 1:1, 1.25:1, 1.5:1, 1.75:1 and 2:1. The mixtures of coal, PKS and adsorbent were briquetted at a molding pressure of 6 ton/cm2 with Jatropha curcas seeds and starch mixture as binding agents. Desulfurization was performed within a temperature range of 300 to 500°C for 720 seconds at an airflow rate of 1.2 L/min. The results showed that the highest desulfurization efficiency (90.6%) was associated with the Ca/S ratio of 2:1 and temperature of 400°C. Moreover, the highest reaction rate constant of desulfurization was 0.280 min-1.
Partial Hydrogenation of Calophyllum Inophyllum Methyl Esters to Increase the Oxidation Stability Joelianingsih Joelianingsih; P. Putra; A.W. Hidayat; R. Fajar
Journal of Engineering and Technological Sciences Vol. 47 No. 5 (2015)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2015.47.5.4

Abstract

Calophyllum inophyllum methyl esters have a low oxidation stability value (5-6 h) caused by high amounts of polyunsaturated fatty acid methyl esters (FAME), especially methyl linoleate. Partial hydrogenation was done to reduce the number of polyunsaturated FAME to transform them into mono-unsaturated. This was performed at 6 bar and 900 rpm with Pd/Al2O3 solid catalyst in a reactor with a capacity of 1 liter. The research purpose was to learn the effects of reaction temperature (80; 100; 120°C) and time (1; 1.5; 2 h) on the FAME composition. The optimum condition of the experiment was obtained at 120°C for 1 h, with 15.47 h as the oxidation stability value, 17.8°C as the cloud point value, and 51.17 as the cetane number. Under this condition, the methyl linoleate content decreased by 59.89% w/w (from 21.869% to 8,770% w/w) and methyllinoleate hydrogenated into methyl elaidate. Meanwhile, the methyl linolenate content decreased by 85,37% w/w (from 0.205% to 0.030% w/w) and methyl linolenate hydrogenated into methyl linolelaidate. These results show that the research met the following standards: a minimum oxidation stability value of 10 h in accordance with the World Wide Fuel Charter (WWFC) 2009, a maximum cloud point value of 18°C and a minimum cetane number 51 in accordance with SNI 7182-2012. The physical properties values of the Calophyllum inophyllum methyl esters were predicted using the empirical equations.
Analysis of the Strength of Timber and Glulam Timber Beams with Steel Reinforcement Arie Putra Usman; Saptahari Sugiri
Journal of Engineering and Technological Sciences Vol. 47 No. 6 (2015)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2015.47.6.1

Abstract

Indonesia is a tropical country with abundant tropical timber that can be used as a building material. Wood is a renewable material, thus making it an environmentally friendly construction material. However, the dimensional limitations of solid wood may pose problems in structural constructions. Wood material also has some disadvantages, such as brittle failure. However, the ductility of wood can be increased because of plasticity occurring in the compression zone. Wood material with good ductility can be obtained by reinforcing it in the tensile zone. This study is about the strength of wood material for use as a material for structural elements. Based on the analytical findings, the bending capacity of wood can be improved by adding reinforcements to the tensile zone.

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