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INDONESIA
Makara Journal of Technology
Published by Universitas Indonesia
ISSN : -     EISSN : -     DOI : -
Core Subject : Science,
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Articles 299 Documents
Water Quality of Rivers and Ponds on DKI Jakarta Hendrawan, Diana
Makara Journal of Technology Vol 9, No 1 (2005)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Original Source | Check in Google Scholar | Full PDF (322.696 KB) | DOI: 10.7454/mst.v9i1.94

Abstract

Thirteen big rivers, some small rivers, and 40 ponds spread over districts at Jakarta city are potential to support human being life. As the population is growing and the usage of stream water is increasing, the condition and quality of rivers and ponds are changing. Crowd housing can affect rivers and ponds pollution, as the people awareness about clean and healthy environment is less. Stream water pollution assessment can be done by counting the effect of pollutant to life of stream water organisms. This assessment unit could be classified into physics, chemical, and biological parameter. To know the water quality, those parameters are transformed into one single value, that is Water Quality Index. The calculation result of Water Quality Index value shows that 83 % of rivers and 79 % of ponds are bad. This condition is caused by less  people and government awareness to maintain rivers and ponds.
Tolerance Limit for Trucks with Excess Load in Transport Regulation in Indonesia Hadiwardoyo, Sigit; Sumabrata, Raden; Berawi, Mohammed
Makara Journal of Technology Vol 16, No 1 (2012)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Original Source | Check in Google Scholar | Full PDF (294.553 KB) | DOI: 10.7454/mst.v16i1.236

Abstract

Reliability of a road is mandatory since damaged will impede the traffic. Destruction is caused by various factors; one of the most important factors is excess load. Overload may give the load of each axle of a vehicle exceeds the determined standard. This condition occurs in trucks exceeding the load limit. In designing the structure of a road based on the method of Directorate General of Highways Ministry of Public Works of the Republic of Indonesia, axle load calculated in equivalent-number, or known as equivalent axle load (EAL), of 8.16 tons of standard axle. Total equivalent-number over the service life is defined as cumulative equivalent standard axle load (CESA). Due to traffic volume exceeding the volume forecast or, in other words there is an excessive load of traffic, it will make CESA achieved faster than planned. This excessive load in Indonesia, however, has been  considered as a factor of environmental condition, so there is a need to introduce a correction factor for EAL as high as 20-25% in the process of designing flexible and rigid pavement so as to reduce early damage.
Biodiesels Characteristics Preparation from Palm Oil Hamid, Tilani; Yusuf, Rachman
Makara Journal of Technology Vol 6, No 2 (2002)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Original Source | Check in Google Scholar | Full PDF (58.923 KB) | DOI: 10.7454/mst.v6i2.44

Abstract

Using vegetable oils directly as an alternative diesel fuel has presented engine problems. The problems have been attributed to high viscosity of vegetable oil that causes the poor atomization of fuel in the injector system and pruduces uncomplete combustion. Therefore, it is necessary to convert the vegetable oil into ester (metil ester) by tranesterification process to decrease its viscosity. In this research has made biodiesel by reaction of palm oil and methanol using lye (NaOH) as catalyst with operation conditions: constant temperature at 60 oC in atmosferic pressure, palm oil : methanol volume ratio = 5 : 1, amount of NaOH used as catalyst = 3.5 gr, 4.5 gr, 5 gr and 5.5 gr and it takes about one hour time reaction. The ester (metil ester) produced are separated from glycerin and washed until it takes normal pH (6-7) where more amount of catalyst used will decrease the ester (biodiesel) produced. The results show that biodiesels properties made by using 3.5 (M3.5) gr, 4.5 gr (M4.5) and 5 (M5.0) gr catalyst close to industrial diesel oil and the other (M5.5) closes to automotive diesel oil, while blending diesel oil with 20 % biodiesel (B20) is able to improve the diesel engine performances.
Optic Properties on AgGaSe2 Polycristal Fabrication Soepardjo, A Harsono; Janusetiawan, I Dewa
Makara Journal of Technology Vol 8, No 3 (2004)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Original Source | Check in Google Scholar | Full PDF (449.194 KB) | DOI: 10.7454/mst.v8i3.85

Abstract

Polycristal AgGaSe2, is compound (I-III-VI2) a semiconductor as basic material for thin film for solar cell. Polycristal was succesfully grown using Bridgmann Method, heated on sequential temperature treatment until 850°C and cooled down slowly until room temperature. Results observed were in the form of ingot (bars) with more or less 3 cm length and 13 mm in diameter. By using X-Ray Fefraction, composition obtained of each element (weight %) was Ag = 29,3996 %, Ga = 36,8123 % and Se = 30,29 % while using X-Ray Difraction lattice parameter obtained/calculated a = 4,4112 Å, c = 8,8854 Å, and c/a = 2,01426.
Fishing Catch and Catch Rate Assesment of Mini Trawl, Trapnet and Setnet Fisheries Firdaus, Muhammad
Makara Journal of Technology Vol 14, No 1 (2010)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Original Source | Check in Google Scholar | Full PDF (190.73 KB) | DOI: 10.7454/mst.v14i1.172

Abstract

This paper purposed to assessment for fishing catch and catch rate of the dragged gear on shrimp, trapnet and setnet fisheries in Tarakan. Catch and effort data (number and species), fishing time of capture unit, were used in analysis qualitative fishing catch and catch rate to describe catch compotition and catch rate from three unit capture fisheries in Tarakan. The result of research showed that in the operation draged gear on shrimp have two main catch are nomei fish and shrimp. on the their two fishing season. Nomei fish as to be a main catch on the trapnet fisheries and pelagic fishes that estuary and coastal of waters as to be a main catch on the setnet fisheries. Dragged gear on shrimp operation with nomei fish as a main catch have catch rate of value are 16.10 kg/hour and trapnet fisheries are 1.67 kg/hour. Catch rate of value from setnet fisheries are 5.39 kg/day and dragged gear on shrimp operation with shrimp as a main catch have a catch rate of value 2.05 kg/hour.
Determination of Operation Condition and Product Dimension Accuracy Optimization of Filament Deposition Modelling on Layer Manufacturing Application Widyanto, Slamet; Tontowi, Alva Edy; Jamasri, Jamasri; Rochardjo, Heru Santoso Budi
Makara Journal of Technology Vol 10, No 2 (2006)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Original Source | Check in Google Scholar | Full PDF (269.348 KB) | DOI: 10.7454/mst.v10i2.117

Abstract

Layer manufacturing process has proven as a process that can produce a high complexity mechanical part. Now, Improvement of LM methods continuously conduct that is aimed to increase precessions and efficiency of these processes. Pressure filament deposition modelling is a form of layer manufacturing process that is designed to produce a plastic part with controlling its semisolid phase. In this research, the equipment of filament depositor is designed and tested to make the product filament deposition. With operation condition observation, the optimal temperature and pressure of deposition process was determined. These experiments used PVC as crystalline material and  polypropylene as amorphous material. To optimize this process, the tensile strength and density test were conducted. The shape of tensile test specimens is based on ASTM 638 standard and made in 3 orientations deposition path, namely: in 0 degree, 45 degree and 90 degree from load force axis. To found the most accurate dimension, controlling the time delay, temperature of build part, feeding speed and variation deposition path was conducted. The results of experiments show that the filament deposition method can only be applied for amorphous material in which it has a semisolid phase. From the tensile strength test, the binding strength among filaments is 0.5 kg/mm2, 20% of the tensile strength of filament. And the density of a sample product, which used the filament diameter of 0.8 mm, is 0.7668 g/cm3. Accuracy of product dimension can be increased by: controlling time delay in location where the motion orientation of hopper filament is changed and controlling temperature of build part surface.
Mechanical Study on using of ACCR Thermal Conductor at 500 kV SUTET Prasetyono, Suprihadi
Makara Journal of Technology Vol 11, No 1 (2007)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Original Source | Check in Google Scholar | Full PDF (220.308 KB) | DOI: 10.7454/mst.v11i1.126

Abstract

At the height of electricity demand increasing recently, circumstance of environment more limited and also expense of high investment, making thermal conductor (conductor thermal resistance) considered to be one of alternative in the electricity transmission bottlenecks. These days it has been developed thermal conductor ACCR (Aluminium Conductor Composite Reinforced) which can operate with temperature up to 240oC, so that making the current carrying capacity being higher than conventional conductor. This research aimed to study load current leading to mechanical characteristic ACCR conductor included tension, length of elongation and sag of conductor. Its expected to be good for develop in construction structure of transmission line which is appropriate to ACCR conductor characteristic. Based on this research it can be concluded that application of ACCR conductor improves transmission line capacities by 100 % on existing ROW and tower.
Modeling of Coupled-Tank System Using Fuzzy Takagi-Sugeno Model Subiantoro, Aries
Makara Journal of Technology Vol 10, No 1 (2006)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Original Source | Check in Google Scholar | Full PDF (630.568 KB) | DOI: 10.7454/mst.v10i1.108

Abstract

This paper describes modeling of coupled tank system based on data measurement using fuzzy Takagi-Sugeno model. The fuzzy clustering method of Gustafson-Kessel algorithm is used to classify input-output data into several clusters based on distance similarity of a member of input-output data from center of cluster. The formed clusters are projected orthonormally into each linguistic variables of premise part to determine membership function of fuzzy Takagi-Sugeno model. By estimating data in each cluster, the consequent parameters of fuzzy Takagi-Sugeno model are calculated using weighted least-squares method. The resulted fuzzy Takagi-Sugeno model is validated by using model performance parameters variance-accounted-for (VAF) and root mean square (RMS) as performance indicators. The simulation results show that the fuzzy Takagi-Sugeno model is able to mimic nonlinear characteristic of coupled-tank system with good value of model performance indicators.
PID Fuzzy Logic Controller System for DC Motor Speed Control Bachri, H Samsul
Makara Journal of Technology Vol 8, No 1 (2004)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Original Source | Check in Google Scholar | Full PDF (353.634 KB) | DOI: 10.7454/mst.v8i1.76

Abstract

A good controller system must have resilience to disturbance and must be able to response quickly and accurately. Problem usually appears when PID controller system was built sensitively hence the systems respon to the disturbance will yield big overshot/undershot then the possibility of  oscillation to be happened is excelsior. When the controller system was built insensitively, the overshot/undershot will be  small but the recovery time will be longer. Hybrid controller system could overcome those problems by combining PID control system with fuzzy logic. The main control of this system is PID controller while the fuzzy logic acts to reduce an overshot/undershot and a recovery time. The fuzzy logic controller is designed with two input error and delta error and one output of the motor speed. The output of fuzzy logic controller should be only half of the PID controller for limiting entirely fuzzy output. This hybrid system design has a better respon time controller system than PID controller without fuzzy logic.
Performance Evaluation of an Optimized Floating Breakwater in Oblique Waves with a Higher-Order Boundary Element Method Mahmuddin, Faisal; Kashiwagi, Masashi
Makara Journal of Technology Vol 18, No 1 (2014)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Original Source | Check in Google Scholar | Full PDF (762.718 KB) | DOI: 10.7454/mst.v18i1.343

Abstract

In the previous study, the optimal performance of a two-dimensional (2D) floating breakwater shape was obtained. The performance of this shape was also confirmed with a model experiment in a towing tank. Moreover, the shape’s performance in three dimensions (3D) was investigated in a subsequent study. However, to predict the shape’s performance in a real application more accurately, the shape’s characteristics in oblique waves must also be evaluated. In this study, the performance and characteristics of the model (hydrodynamic forces, body motions, wave elevations, and drift forces) are computed using a higher-orderboundary element method (HOBEM). The HOBEM, which is based on the potential flow theory and uses quadratic representation for quadrilateral panels and velocity potentials, can be used to obtain more accurate results with fewer panels compared to the conventional panel method (CPM). The computational accuracy is confirmed by using Haskind-Newman and energy conservation relations. In thisstudy, 3D wave effects were verified, and the body motions were much smaller compared to the 2D case. In addition, although the performance in terms of wave elevations depends on the measurement positions, the optimal performance obtained in the 2D case can be realized for a longer body length. 

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