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INDONESIA
Makara Journal of Technology
Published by Universitas Indonesia
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Core Subject : Science,
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Articles 17 Documents
Search results for , issue " Vol 14, No 2 (2010)" : 17 Documents clear
Hydrogen Absorption Induced Slow Crack Growth in Austenitic Stainless Steels for Petrochemical Pressure Vessel Industries Rusli, Ronnie
Makara Journal of Technology Vol 14, No 2 (2010)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v14i2.186

Abstract

Type 304Land type 309 austenitic stainless steels were tested either by exposed to gaseous hydrogen or undergoing polarized cathodic charging. Slow crack growth by straining was observed in type 304L, and the formation of α‘ martensite was indicated to be precursor for such cracking. Gross plastic deformation was observed at the tip of the notch, and a single crack grew slowly from this region in a direction approximately perpendicular to the tensile axis. Martensite formation is not a necessary condition for hydrogen embrittlement in the austenitic phase.
Dye Sensitized Solar Cell with Conventionally Annealed and Post-Hydrothermally Treated Nanocrystalline Semiconductor Oxide TiO2 Derived from Sol-Gel Process Yuwono, Akhmad; Munir, Badrul; Ferdiansyah, Alfian; Rahman, Arif; Handini, Wulandari
Makara Journal of Technology Vol 14, No 2 (2010)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v14i2.177

Abstract

Dye-sensitized solar cell (DSSC) is one of the very promising alternative renewable energy sources to anticipate the declination in the fossil fuel reserves in the next few decades and to make use of the abundance of intensive sunlight energy in tropical countries like Indonesia. In the present study, TiO2 nanoparticles of different nanocrystallinity was synthesized via sol−gel process with various water to inorganic precursor ratio (Rw) of 0.85, 2.00 and 3.50 upon sol preparation, followed with subsequent drying, conventional annealing and post-hydrothermal treatments. The resulting nanoparticles were integrated into the DSSC prototype and sensitized with an organic dye made of the extract of red onion. The basic performance of the fabricated DSSC has been examined and correlated to the crystallite size and band gap energy of TiO2 nanoparticles. It was found that post-hydrothermally treated TiO2 nanoparticles derived from sol of 2.00 Rw, with the most enhanced nanocrystalline size of 12.46 nm and the lowest band gap energy of 3.48 eV, showed the highest open circuit voltage (Voc) of 69.33 mV.
Concept Design and Testing of Multi-Nozzle Water Mist Fire Suppression System Sumarsono, Danardono A.; Nugroho, Yulianto S.; Mariance, Mariance; Ariasa, I Gede
Makara Journal of Technology Vol 14, No 2 (2010)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v14i2.191

Abstract

In this work a flexible design of multi-nozzle arrangement of water mist fire suppression system was studied. The source of fire was a 65 mm diameter cooking oil fire. An investigation on the impact of nozzle arrangement on the temperature profile of fires was conducted. The occurance of oil splash due to the application of water mist was also studied. The water mist systems developed in the present work can effectively extinguish cooking oil fires and prevented them from re-ignition. The spray angle, discharge pressure, and water flow rate were important factors to determine the effectiveness of water mist in extinguishing cooking oil fires.
WiMAX Implementation as Existing Hotspot Network Backhaul in Jakarta Sirat, Djamhari; Asvial, Muhamad; Marpaung, Luther B.
Makara Journal of Technology Vol 14, No 2 (2010)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v14i2.182

Abstract

The development of Broadband Wireless Access (BWA), such as WiMAX, as a global standard for data transmission media has been used by high speed internet access provider. WiMAX application which supported by capabilities of interoperability, flexibility and commercial aspect make the internet services become more efficient, cheaper and easier to the customer. This phenomenon should be responded by ISPs. Based on technical and financial aspect in deciding the implementation of Wireless Network with WiMAX technology as a substitute, this research will observe and analyze the projection of WiMAX technology implementation as a backhaul for the existing Wi-Fi’s network in Jakarta. This paper will describe the calculation based on the amount of hotspots registered in IIX and average peak traffic per regional from technical aspect with several pricing and technology combination. The result give the basic figures in investing WiMAX as substitute technology for backhaul in hotspot network and also will show its growth in 5 years.
Simulation on the Use of LOSAT Data for Rice Field Mapping Trisasongko, Bambang H.; Panuju, Dyah R.; Tjahjono, Boedi; Barus, Baba; Wijayanto, Hari; Raimadoya, Mahmud A.; Irzaman, Irzaman
Makara Journal of Technology Vol 14, No 2 (2010)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v14i2.187

Abstract

Since the launch of LAPAN-TUBSAT satellite in 2007, Indonesia has been developing mission on earth observation missions for various applications. The next generation mission, called LAPAN-ORARI Satellite (LOSAT), is currently under development and expected to be launched in 2011. In order to facilitate the applications, a thorough assessment of the sensor should be made. This paper presents an examination of simulated LOSAT data for rice monitoring and mapping purposes coupled with QUEST statistical tree. We found that three-band simulated LOSAT data were suitable for the task with reasonably high accuracy.
Immobilization of Saccharomyces Cerevisiae in Rice Hulls for Ethanol Production Martini, Edita; Andriani, Dian; GobiKrishnan, Sriramulu; Kang, Kyeong; Bark, Surn-Teh; Sunwoo, Changshin; Prasetya, Bambang; Park, Don-Hee
Makara Journal of Technology Vol 14, No 2 (2010)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v14i2.178

Abstract

The whole cell immobilization in ethanol fermentation can be done by using natural carriers or through synthetic carriers. All of these methods have the same purpose of retaining high cell concentrations within a certain defined region of space which leads to higher ethanol productivity. Lignocellulosic plant substance represents one of highly potential sources in ethanol production. Some studies have found that cellulosic substances substances can also be used as a natural carrier in cell immobilization by re-circulating pre-culture medium into a reactor. In this experiment, rice hulls without any treatment were used to immobilize Saccharomyces cerevisiae through semi solid state incubation combined with re-circulating pre-culture medium. The scanning electron microscopy (SEM) pictures of the carrier show that the yeast cells are absorbed and embedded to the rice hull pore. In liquid batch fermentation system with an initial sugar concentration of 50 g/L, nearly 100% total sugar was consumed after 48 hours. This resulted in an ethanol yield of 0.32 g ethanol/g glucose, which is 62.7% of the theoretical value. Ethanol productivity of 0.59 g/(L.h) is 2.3 fold higher than that of free cells which is 0.26 g/(L.h). An effort to reuse the immobilized cells in liquid fermentation system showed poor results due to cell desorption in the first batch which led to high sugar concentration inhibitory effect in the second batch fermentation. This might be solved by using semi solid fermentation process in the future work.
The Stability Characteristics of Sandbag Submerged Breakwater Fatnanta, Ferry; Pratikto, Widi; Armono, Haryo; Citrosiswoyo, Wahyudi
Makara Journal of Technology Vol 14, No 2 (2010)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v14i2.192

Abstract

Breakwater is one of coastal structures to overcome problems of abrasion. Due to difficulties in obtaining rock material at the coastal area. The using of sandbags as a breakwater provides advantages in utilizing local materials. A Sandbag has a smooth surface, so the internal shear forces are relatively small. According to these phenomena, the research for parameters that are expected to affect the stability of the sand bags. These parameters are a slope, shape and formation of sand bags. This experimental research conducted in two dimensional physical model and took place on the flume tank of Ocean Engineering Department, Faculty of Marine Technology, ITS. Scaled model 1 : 10. The bag was made in shapes, B1 and B2. Sand bags were prepared with the slope 1 : 1.5 and 1 : 2,0, width of top was 60 cm. The waves were regular waves, period of 1.5 seconds. The wave height was adjusted with the level of stability sand bags. It showed that the response of the sandbag was influenced by interlocking between sandbags. As a result, the stability depended on the change of wave forces, as a consequence of the change of slope and cross areas due to sandbags shape and formation type.
Plant Growth Modeling Using L-System Approach and Its Visualization Suyantohadi, Atris; Alfiyan, Alfiyan; Hariadi, Mochamad; Purnomo, Mauridhi
Makara Journal of Technology Vol 14, No 2 (2010)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v14i2.183

Abstract

The visualizationof plant growth modeling using computer simulation has rarely been conducted with Lindenmayer System (L-System) approach. L-System generally has been used as framework for improving and designing realistic modeling on plant growth. It is one kind of tools for representing plant growth based on grammar sintax and mathematic formulation. This research aimed to design modeling and visualizing plant growth structure generated using L-System. The environment on modeling design used three dimension graphic on standart OpenGL format. The visualization on system design has been developed by some of L-System grammar, and the output graphic on three dimension reflected on plant growth as a virtual plant growth system. Using some of samples on grammar L-System rules for describing of the charaterictics of plant growth, the visualization of structure on plant growth has been resulted and demonstrated.
Development of Technology Parameter Towards Shipbuilding Productivity Predictor Using Cubic Spline Approach Suwasono, Bagiyo; Widjaja, Sjarief; Zubaydi, Achmad; Yuliadi, Zaed; Budiantara, I Nyoman
Makara Journal of Technology Vol 14, No 2 (2010)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v14i2.188

Abstract

Ability of production processes associated with state-of-the-art technology, which allows the shipbuilding, is customized with modern equipment. It will give impact to level of productivity and competitiveness. This study proposes a nonparametric regression cubic spline approach with 1 knot, 2 knots, and 3 knots. The application programs Tibco Spotfire S+ showed that a cubic spline with 2 knots (4.25 and 4.50) gave the best result with the value of GCV = 56.21556, and R2 = 94.03%.Estimation result of cubic spline with 2 knots for the PT. Batamec shipyard = 35.61 MH/CGT, PT. Dok & Perkapalan Surabaya = 27.49 MH/CGT, PT. Karimun Sembawang Shipyard = 27.49 MH/CGT, and PT. PAL Indonesia = 19.89 MH/CGT.
An Empirical Model for Build-Up of Sodium and Calcium Ions in Small Scale Reverse Osmosis Nasir, Subriyer
Makara Journal of Technology Vol 14, No 2 (2010)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v14i2.179

Abstract

A simple models for predicting build-up of solute on membrane surface were formulated in this paper. The experiments were conducted with secondary effluent, groundwater and simulated feed water in small-scale of RO with capacity of 2000 L/d. Feed water used in the experiments contained varying concentrations of sodium, calcium, combined sodium and calcium. In order to study the effect of sodium and calcium ions on membrane performance, experiments with ground water and secondary effluent wastewater were also performed. Build-up of salts on the membrane surface was calculated by measuring concentrations of sodium and calcium ions in feed water permeate and reject streams using Atomic Absorption Spectrophotometer (AAS). Multiple linear regression of natural logarithmic transformation was used to develop the model based on four main parameters that affect the build-up of solute in a small scale of RO namely applied pressure, permeate flux, membrane resistance, and feed concentration. Experimental data obtained in a small scale RO unit were used to develop the empirical model. The predicted values of theoretical build-up of sodium and calcium on membrane surface were found in agreement with experimental data. The deviation in the prediction of build-up of sodium and calcium were found to be 1.4 to 10.47 % and 1.12 to 4.46%, respectively.

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