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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 8 Documents
Search results for , issue " Vol 13, No 2 (2009)" : 8 Documents clear
Implementation of Six Sigma Method to Maintain The Quality of Construction Projects Latief, Yusuf; Utami, Retyaning
Makara Journal of Technology Vol 13, No 2 (2009)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v13i2.163

Abstract

Six sigma (6-sigma) is a method that widely developed in the world, especially in manufacturing industry to decrease failures in achieving good quality in construction projects. The objective of this research is to explore the existing condition of quality management and the aplication of 6-sigma method in maintaining quality of construction projects. Structured interviews to experienced experts and people who were recommended by their companies were conducted. Non-parametric analysis using frequencies distribution procedures were used for analysis. The result shows that existing condition in quality management of construction project in Indonesia have been implemented 6-sigma method approach, that concern with is how to adapt with either from internal or external condition of that project.
Mechanical properties of ramie fiber reinforced epoxy lamina composite for socket prosthesis Soemardi, Tresna; Kusumaningsih, Widjajalaksmi; Irawan, Agustinus
Makara Journal of Technology Vol 13, No 2 (2009)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v13i2.168

Abstract

This paper presents an investigation into the application of natural fiber composite especially ramie fiber reinforced epoxy lamina composite for socket prosthesis. The research focuses on the tensile and shear strength from ramie fiber reinforced epoxy lamina composite which will be applied as alternative material for socket prosthesis. The research based on American Society for Testing Material (ASTM) standard D 3039/D 3039M for tensile strength and ASTM D 4255/D 4255M-83 for shear strength. The ramie fiber applied is a fiber continue 100 % Ne14S with Epoxy Resin Bakelite EPR 174 as matrix and Epoxy Hardener V-140 as hardener. The sample composite test made by hand lay up method. Multiaxial characteristic from ramie fiber reinforced epoxy composite will be compared with ISO standard for plastic/polymer for health application and refers strength of material application at Prosthetics and Orthotics. The analysis was completed with the mode of the failure and the failure criterion observation by using Scanning Electron Microscope (SEM). Based on results of the research could be concluded that ramie fiber reinforced epoxy composite could be developed further as the alternative material for socket prosthesis on Vf 40-50%. Results of the research will be discussed in more detail in this paper.
Simple ML Detector for Multiple Antennas Communication System Taqwa, Ahmad; Soegijoko, Soegijardjo; Sugihartono, Sugihartono; Tjondronegoro, Suhartono
Makara Journal of Technology Vol 13, No 2 (2009)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v13i2.164

Abstract

In order to support providing broadband wireless communication services against limited and expensive frequency bandwidth, we have to develop a bandwidth efficient system. Therefore, in this paper we propose a closed-loop MIMO (Multiple-Input-Multiple-Output) system using ML (Maximum Likelihood) detector to optimize capacity and to increase system performance. What is especially exciting about the benefits offered by MIMO is that a high capacity and performance can be attained without additional frequency-spectral resource. The grand scenario of this concept is the attained advantages of transformation matrices having capability to allocate transmitted signals power suit to the channel. Furthermore, product of these matrices forms parallel singular channels. Due to zero inter-channels correlation, thus we can design ML detector to increase the system performance. Finally, computer simulations validates that at 0 dB SNR our system can reach optimal capacity up to 1 bps/Hz and SER up to 0.2 higher than opened-loop MIMO.
Effects of Ph on Calcium Carbonate Precipitation Under Magnetic Field Saksono, Nelson; Yuliusman, Yuliusman; Bismo, Setijo; Soemantojo, Roekmijati; Manaf, Azwar
Makara Journal of Technology Vol 13, No 2 (2009)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v13i2.165

Abstract

Magnetic field effect on CaCO3 precipitation is the key parameter in evaluating the effectiveness of Anti-scale Magnetic Treatment (AMT). The purpose of this study was to investigate magnetic fields influence on CaCO3 precipitation in high and low super-saturated CaCO3 solution by varied pH CaCO3 solution using circulation flow fluid system. The observation results in the high super saturated solution (pH 8.5) showed the increase of precipited CaCO3 in magnetized solutions compared to those in non-magnetic solution during circulation process. In the low super-saturated CaCO3 solution (pH 6.4) it was found that magnetic treatment increased CaCO3 precipitation after circulation process. In high super-saturated solution, magnetic field strengthens ion interactions, which reduce precipitation during circulation process. However, in low super-saturated CaCO3 solution, magnetic field weakens hydrate ion interaction which indicated by decreasing of the conductivity of solution. It increases the precipitation of CaCO3 after the circulation of magnetization process has completed.
Potency of Thermoelectric Generator for Hybrid Vehicle Putra, Nandy; Koestoer, Raldi; Adhitya, Mohammad; Roekettino, Ardian; Trianto, Bayu
Makara Journal of Technology Vol 13, No 2 (2009)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v13i2.161

Abstract

Thermoelectric Generator (TEG) has been known as electricity generation for many years. If the temperature difference occurred between two difference semi conductor materials, the current will flow in the material and produced difference voltage. This principle is known as Seebeck effect that is the opposite of Peltier effect Thermoelectric Cooling (TEC). This research was conducted to test the potential of electric source from twelve peltier modules. Then, these thermoelectric generators were applied in hybrid car by using waste heat from the combustion engine. The experiment has been conducted with variations of peltier module arrangements (series and parallels) and heater as heat source for the thermoelectric generator, with variations of heater voltage input (110V and 220V) applied. The experimental result showed that twelve of peltier modules arranged in series and heater voltage of 220V generated power output of 8.11 Watts with average temperature difference of 42.82°C. This result shows that TEG has a bright prospect as alternative electric source.
Performance of Hollow Fiber Membrane Gas-Liquid Contactors to Absorb CO2 Using Diethanolamine (Dea) as a Solvent Kartohardjono, Sutrasno; Nata, Pan; Prasetio, Eko; Yuliusman, Yuliusman
Makara Journal of Technology Vol 13, No 2 (2009)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v13i2.166

Abstract

This study uses DEA solution to absorb CO2 from the gas flow through the hollow fiber membrane contactors. This study aims to evaluate the performance of hollow fiber membrane contactors to absorb CO2 gas using DEA solution as solvent through mass transfer and hydrodynamics studies. The use of DEA solution is to reduce the mass transfer resistance in the liquid phase, and on the other side, the large contact area of the membrane surface can cover the disadvantage of membrane contactors; additional mass transfer resistance in the membrane phase. During experiments, CO2 feed flows through the fiber lumens, while the 0.01 M DEA solution flows in the shell side of membrane contactors. Experimental results show that the mass transfer coefficients and fluxes of CO2 increase with an increase in both water and DEA solution flow rates. Increasing the amount of fibers in the contactors will decrease the mass transfer and fluxes at the same DEA solution flow rate. Mass transfer coefficients and CO2 fluxes using DEA solution can achieve 28,000 and 7.6 million times greater than using water as solvent, respectively. Hydrodynamics studies show that the liquid pressure drops in the contactors increase with increasing liquid flow rate and number of fibers in the contactors. The friction between water and the fibers in the contactor was more pronounced at lower velocities, and therefore, the value of the friction factor is also higher at lower velocities.
Semi-Automatic Image Segmentation for Volumetric Visualization of Pelvis CT Scan-Images Suprijanto, Suprijanto; Muchtadi, Farida; Setiawan, Irwan
Makara Journal of Technology Vol 13, No 2 (2009)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v13i2.162

Abstract

The current development of computerized tomography (CT) has enable us to obtain cross sectional image using multi slicing techniques in an order of few seconds. The obtained images represent several tissue structures on cross section slice being imaged. One challenge to help diagnosis using CT images is extracting an anatomic structure of interest using a method of image segmentation and volumetric visualization with the assistance of computers. In case of volumetric visualization of pelvis bones extracted from multi-slice CT images, whole images which are containing part of pelvis bone structures must be segmented. In this research, an image segmentation technique based on active contour is implemented for semi-automatic multi slice image segmentation. Image segmentation steps are initialized with a define model of 2D curve on the first slice image manually. Next, its model curve is deformed to reach the final result of 2D curve that fits to boundary edges of pelvis bone image. The final result of 2D curve on previous slice image was used as an initialization model of 2D curve on the next slice images. This process will continue until the final slice image. This segmentation method was compared with the segmentation method based on threshold from homogenous intensity distribution and manual segmentation method. Quantitative analysis from the results of segmentation on each slice and qualitative analysis on the representation of volumetric visualization are performed in this research.
Intermetallic Cu3Sn Phase Layer on Electrode’s Tip of Galvanized Resistance Spot Welding Anis, Muhammad; Irsyadi, Aulia; Ferdian, Deni
Makara Journal of Technology Vol 13, No 2 (2009)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v13i2.167

Abstract

A resistance spot welding method is commonly used in automotive industries application. In a resistance spot welding method, the copper electrode has a significant role as an electric current carrier for joining thin metal sheet. This research was focused on studying the effect of tin layer at the electrode tip for joining galvanized steel sheet. The main variable of this research is in the thickness of the intermetallic Cu3Sn layer. The result showed that the introduction of tin layer less than 1 μm in thickness on the electrode tip gives a comparable shear strength and nugget diameter distribution with the unplated electrode tip.

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