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Makara Journal of Technology
Published by Universitas Indonesia
ISSN : 23552786     EISSN : 23564539     DOI : https://doi.org/10.7454/mjt
Core Subject : Science, Engineering,
Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Electrical & Electronics Engineering Engineering Materials Science & Nanotechnology Mechanical Engineering
MAKARA Journal of Technology is a peer-reviewed multidisciplinary journal committed to the advancement of scholarly knowledge and research findings of the several branches of Engineering and Technology. The Journal publishes new results, original articles, reviews, and research notes whose content and approach are of interest to a wide range of scholars. It also offers rapid dissemination. MAKARA Journal of Technology covers the recent research in several branches of engineering and technology include Electrical & Electronics Engineering, Computer Engineering, Mechanical Engineering, Chemical & Bioprocess Engineering, Material & Metallurgical Engineering, Industrial Engineering, Civil & Architecture Engineering, and Marine Engineering. Criteria used in determining acceptability of contributions include newsworthiness to a substantial part of the engineering & technology and the effect of rapid publication on the research of others. This journal, published three times each year, is where readers look for the advancement of discoveries in engineering and technology.
Arjuna Subject : Teknik (semua kategori) - Teknik (Lain-Lain)
Articles 8 Documents
 1 
Search results for , issue "Vol. 22, No. 2" : 8 Documents clear
Microstructures and Hardness of TIG Welded Experimental 57Fe15Cr25Ni Steel Parikin, Parikin; Dani, Mohammad; Rivai, Abu Khalid; Ismoyo, Agus Hadi; Iskandar, Riza; Dimyati, Arbi
Makara Journal of Technology Vol. 22, No. 2
Publisher : UI Scholars Hub

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Abstract

The microstructures and hardness of tungsten inert gas (TIG) welded experimental 57Fe15Cr25Ni steel were investigated through optical–scanning electron microscopy analyses and with a hardness tester, respectively. The welding process restructured the constituent atoms into regular and irregular crystal lattices. Rapid cooling of the weld metal allowed the formation of a dendritic (columnar) structure, with porous grains. By contrast, slow cooling influenced HAZ and led to the formation of grain structures. The crystal lattice became more organized and larger than other zones. Meanwhile, the base metal formed circular nets that covered large area inside thick and thin grain boundaries. The diffraction patterns revealed texturing in the weld metal. The crystallite orientation changed from (111) to (200) and (220) planes. The weld metal profile broadened (amorphous) and had full width at half maximum (fwhm) value larger than those in HAZ and the base metal. The weld metal possessed hardness of 121 HV, which is slightly lower than the hardness of the base metal (130 HV). HAZ exhibited the highest hardness value (152 HV). Hardening was influenced by carbon and outer oxygen migration to the grain boundaries, which formed colonies, i.e., chromium carbide, aluminum carbide, aluminum oxide, silicone oxide, and silicon carbide (precipitation hardening). Welding (heat) may change the microstructure and hardness of HAZ and the weld metal region, which would be brittle and very critical in responding to applied loads.
Satellite-Based Monitoring of Spatiotemporal Changes in Batudulang Forest in Sumbawa, Indonesia Muslim, Mohammad; Witarto, Arief Budhi; Indrajaya, Wahyu
Makara Journal of Technology Vol. 22, No. 2
Publisher : UI Scholars Hub

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Abstract

Space-based earth observation technology applicable to forest inventory and monitoring is well known in the scientific community. High-resolution satellite images form an important data source for forest mapping and change detection at regional and national scales. The value of forest change information derived from remote sensing data is significantly enhanced if this information is integrated into a spatially explicit geographic information system. Satellite-based rapid assessment was conducted to measure spatiotemporal changes in Batudulang forest over the years. The general approach to quantify change in the spatial aspect of the forest involved change detection using moderate-resolution imaging spectro-radiometer satellite-based normalized difference vegetation index. A further top–down approach using high-resolution data from Google Earth was used to complement the mapping and specifically identify areas of spatial, temporal, and thematic change on a grid basis (1×1 sq. km.). Results from change detection studies revealed that the forest area changed from 287 sq. km. in 2008 to 189 sq. km. in 2016. Visual image interpretation of high-resolution Google Earth images (2001–2013) analyzed 63 grids, of which 30 showed significant change and 33 exhibited no change.
Internet Traffic Forecasting Model Using Self Organizing Map and Support Vector Regression Method Laoh, Enrico; Agustriwan, Fakhrul; Megawati, Chyntia; Surjandari, Isti
Makara Journal of Technology Vol. 22, No. 2
Publisher : UI Scholars Hub

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Abstract

Internet traffic forecasting is one of important aspect in order to fulfill the customer demand. So, the service quality of internet service provider (ISP) can be maintained at the good level. In this study self organizing map (SOM) and support vector regression (SVR) algorithm are used as forecasting method. SOM is first used to decompose the whole historical data of traffic internet into clusters, while SVR is used to build a forecasting model in each cluster. This method is used to forecast ISPs traffic internet in Jakarta and surrounding areas. The result of this study shows that SOM-SVR method gives more accurate result with smaller error value compared to that of the SVR method.
Benchmarking Product Service System of Generator Set Distributors Tiurindah, Venny Violetta; Sofianti, Tanika Dewi
Makara Journal of Technology Vol. 22, No. 2
Publisher : UI Scholars Hub

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Abstract

Power generation is an industry that is essential to sustain daily life and competes with generator set distributors. The product service system of distributors must be improved to survive the competition. This research aims to develop tools for benchmarking the product service system of generator set distributors. Benchmarking identifies gaps between a product and other competitors’ products. In this work, a product service system board is used to visualize the current product service system of a generator set distributor. A PPIAF framework and a SERVQUAL framework are adapted to assess product performance and service quality, respectively. AHP is used as weighting method. The survey results provide ideas for improving the current product service system of generator set distributors. Further studies must use detailed measure weighting methods and implement the product service system board to assess service quality.
Mapping of Bruise of Oil Palm Fresh Fruit Bunch during Loading and Transportation from Field to Mill Krisdiarto, Andreas Wahyu
Makara Journal of Technology Vol. 22, No. 2
Publisher : UI Scholars Hub

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Abstract

Fresh fruit bunches (FFBs) are used as raw materials for palm oil, and their transport from a field is a critical step to maintain their quality. Fruit integrity should be maintained so the mill can efficiently obtain palm oil with less than 5% free fatty acid content. Physical treatments for FFBs during loading to truck bins and transport may cause physical injuries. This research aimed to map fruit bruises. The map can be used as a basis in managing transport of FFBs. Physical injuries were assessed by bruise index (BI), which was calculated by measuring the bruise area and weight of the fruit. The experiment was conducted in a completely randomized design (CRD) with five replications. The treatments included truck type (wood bin or steel bin), truck age (more and less than 5 years), and FFB position in the truck bin (bottom, middle, top layer, front, center, or rear). Data were described by graphical method and analyzed statistically with one-way ANOVA. Results indicated loosen fruits and increased bruising of matured fruits loaded to the truck bin. BI (1.97–2.07) was not significantly different among FFBs placed in different positions in the truck bin. Nevertheless, FFB at the middle position showed higher degree of bruising than FFBs at the other positions. Fruit bruise was more prevalent when FFBs were transported by an old truck (>5years) rather than by a young truck, with BI values of 2.01 and 1.82, respectively.
Strength Structure Analysis of Main Gate Graving Dock Using Pontoons for Condition Repairs Budianto, Budianto
Makara Journal of Technology Vol. 22, No. 2
Publisher : UI Scholars Hub

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Abstract

Main gate graving dock with pontoon type can certainly suffered some level of damage after a long period of operation. Many employments within the graving dock can delay the process repair of main gate. The main gate may not be opened, because employees are still working to ship fabrication process under sea waterline. For accommodate these interrelated conditions, the best solution with repair one side of the main gate with type pontoon and employees can still work ship fabrication process in graving dock conducted simultaneously. The repair process conditions must be required main gate structure that consists of only one part of the shell withstand the forces that occur, such as weight self and sea pressure. It must be considered with analysis of the strength structures of main gate graving dock with pontoon type. Finite element method can solve the problem of structural analysis using the element discretion approach to find a node or joint displacement and the forces that occur in structural repair conditions at main gate. The maximum bending stress value obtained during the main gate repair process is 153 mPa, and the allowable stress value is classified as 157 mPa. Since these conditions are approaching the allowable limit, the main gate needs to be given insert plates for reinforcement. Deformation is found to be 12 mm, and the deformation limit is 35 mm based on the rule's classification.
Investigation of Ship Hull Girder Strength with Grounding Damage Alie, Muhammad Zubair Muis; Adiputra, Ristiyanto
Makara Journal of Technology Vol. 22, No. 2
Publisher : UI Scholars Hub

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Abstract

The objective of the present study is to investigate ship hull girder strength as a result of grounding damage upon longitudinal bending. A bulk carrier and tanker are analyzed and Smith’s Method is adopted and implemented in the analysis program. An efficient solution procedure is performed by assuming the cross-section remains plane and the vertical bending moment is applied to the cross section. As a fundamental case, the damage is simply created by removing the elements from the cross section. Welding residual stress, initial imperfections, and crack extensions are not considered. The grounding damage is made by two conditions, namely those are placed at the center part of the cross section and those located at an asymmetric position. To determine the ultimate strength, which includes the progressive collapse behavior of ship hull with damage, the simply supported scenario is imposed to the cross section and hogging and sagging conditions are taken into account. The results obtained for intact and damage conditions by the in-house program are compared with one another to observe the collapse behavior in advance.
Effects of the Preheating Temperature on the Crystal Structure and Texture of Martensitic Stainless Steel Priyanto, Tri Hardi; Muslih, Rifai; Mugirahardjo, Herry; Bharoto, Bharoto; Insani, Andon; Muzzakiy, Muzzakiy
Makara Journal of Technology Vol. 22, No. 2
Publisher : UI Scholars Hub

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Abstract

Theoretically, the preheating temperature refers to the start martensite temperature (Ms), and the martensite transformation can be considered as the conservation of the invariant habit-plane in the lattice structure. The habit-plane is the interface plane between austenite and martensite as measured on a macroscopic scale. From the calculation, Ms = 252 °C. The martensite formation can be affected by temperature or stress treatment. In this experiment, temperature treatment was conducted. The sample was treated at 250 °C ± 10 °C. Before and after the pre-heat treatment, the sample was characterized using the neutron diffraction method. BATAN’s Texture Diffractometer (DN2) with a neutron wavelength of 1.2799Å was used to characterize the sample. Analysis of the crystal structure showed that there are three phases before the preheating. The lattice parameters (a) obtained were as follows: for the -phase, a = 2.8501 ± 0.0004 Å; for the α’-phase, a= b =2.517 ± 0.003 Å, and c= 3.581 ± 0.002 Å; for the -phase, a= 3.5884 ± 0.0004 Å, Rwp = 17.94%, and  = 1.33. After preheating, only the -phase appears with a = 3.5830 ± 0.0005 Å, Rwp = 26.03%, and  = 1.17. The orientation distribution function is modeled by the sample symmetrization model based on triclinic to orthorhombic sample symmetry. It shows that, before being preheated, the -phase has {100} <001> with texture index (F2 ) between 0.701 m.r.d. to 3.650 m.r.d., the α-phase has a texture index between 0.923 m.r.d. to 1.768 m.r.d., and the ’-phase has a texture index between 0.910 m.r.d. to 1.949 m.r.d. After being preheated, the -phase also has {100} <001> with a texture index between 0.846 m.r.d. to 3.706 m.r.d. It can be concluded, that because of the high preheating temperature, a phase change from martensite to austenite occurred that allowed the sample to be welded easily. After preheating, the -phase has the same cubic type orientation {100} <001>, and the texture index is nearly the same as that before preheating, with not martensite present.

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