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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 15 Documents
Search results for , issue " Vol 15, No 1 (2011)" : 15 Documents clear
The Solvent Effectiveness on Extraction Process of Seaweed Pigment Warkoyo, Warkoyo; Saati, Elfi
Makara Journal of Technology Vol 15, No 1 (2011)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v15i1.195

Abstract

Eucheuma cottonii seaweed is a species of seaweed cultured in Indonesian waters, because its cultivation is relatively easy and inexpensive. It has a wide variety of colors from green to yellow green, gray, red and brown, indicating photosynthetic pigments, such as chlorophyll and carotenoids. An important factor in the effectiveness of pigment extraction is the choice of solvent. The correct type of solvent in the extraction method of specific natural materials is important so that a pigment with optimum quality that is also benefical to the society can be produced. The target of this research is to obtain a high quality solvent type of carotenoid pigment. This research was conducted using a randomized block design with three (3) replications involving two factors namely solvent type (4 levels: aceton, ethanol, petroleum benzene, hexan & petroleum benzene) and seaweed color (3 levels: brown, green and red). Research results indicated that each solvent reached a peak of maximal absorbance at  410-472 nm, namely carotenoids. The usage of acetone solvent gave the best pigment quality. Brown, green and red seaweed have pigment content of 1,28 mg/100 g; 0,98 mg/100 g; 1,35 mg/100 g and rendement of 6,24%; 4,85% and 6,65% respectively.
Circuit Design for Sensor Detection Signal Conditioner Nitrate Content Manurung, Robeth; Debataraja, Aminuddin; Hiskia, Hiskia
Makara Journal of Technology Vol 15, No 1 (2011)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v15i1.200

Abstract

Nitrate is one of macro nutrients very important for agriculture. The availability of nitrate in soil is limited because it is very easy to leaching by rain, therefore nitrate could be contaminated ground water by  over-process of fertilizer. This process could also produce inefficiency in agriculture if it happened continuesly without pre-analysis of farm field. The answer those problems, it is need to develop the ion sensor system to measure concentrations of nitrat in soil. The system is consist of nitrate ion sensor device, signal conditioning and data acquisition circuit. The design and fabrications of signal conditioning circuit which integrated into ion nitrate sensor system and will apply for agriculture. This sensor has been used amperometric with three electrodes configuration: working, reference  and auxiliarry; the ion senstive membrane has use conductive polymer. The screen printing technique has been choosen to fabricate electrodes and deposition technique for ion sensitive membrane is electropolymerization. The characterization of sensor has been conducted using nitrate standard solution with range of concentration between 1 µM–1 mM. The characterization has shown that sensor has a good response with cureent output between 2.8–4.71 µA, liniearity factor is 99.65% and time response 250 second.
Ergonomic Analysis of Garment Industry using Posture Evaluation Index (PEI) in Virtual Environment Muslim, Erlinda; Nurtjahyo, Boy; Ardi, Romadhani
Makara Journal of Technology Vol 15, No 1 (2011)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v15i1.205

Abstract

This research tried to study, in a virtual environment, the ergonomics of four divisions in garment industry: cutting division, sewing division, button division, and finishing division. Variables that influence the working conditions in each division are different; depend on the real situations that happened. The purpose is to assess the real working conditions based on ergonomics  study  using Posture Evaluation Index (PEI). PEI integrates  the scores of  low back analysis (LBA), ovako working  posture  (OWAS),  and  rapid  upper  limb assessment  (RULA).  Analysis  phase  was  done  using  digital  human model  in  virtual  environment  that  available  on  Jack  6.0.  The  results show  that  the  working  conditions  in  garment industry had enough amount of risk that can injured the musculoskeletal system of the workers. This research enriches the  body  of  ergonomics  knowledge  in Indonesia  because  it  is  the  first  research  in  Indonesia that  applied  virtual environment approach to ergonomics analysis in industry.
Cradle to Gate Simple Life Cycle Assessment of Biodiesel Production in Indonesi Hidayatno, Akhmad; Zagloel, Teuku; Purwanto, Widodo; Carissa, Carissa; Anggraini, Lindi
Makara Journal of Technology Vol 15, No 1 (2011)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v15i1.196

Abstract

The focus of this research is to analyze potential environmental impact in the supply chain of palm oil biodiesel industries. Simple Life Cycle Assessment (LCA) is applied to analyze impacts, produced by the three main units in the supply chain of Palm-Oil-based Biodiesel, which are Palm Plantation, CPO mill, and Biodiesel Plant. We developed LCA calculation model using spreadsheet software, used to assess a number of input scenarios to evaluate the best scenario, in variation of: land quality, land area and the rate of clearing, land clearing technique and type of the original land. The biggest potential environmental impact is the contribution to global warming impact which emissions are produced mostly from unit plantation. Although plantation has biggest potential to contribute to environmental impact, it also gives biggest reduction to global warming impact. In general, the biggest environmental impact in the LCA category is climate change, followed by photo-oxidant formation and eutrophication. The biggest impacts in the supply chain are from the plantation, especially when choosing the right technique for land clearing. In addition, due to LCA linearity nature, the scenario that we tested does not change the total accumulative environmental impacts.
Natural Gas as Petroleum Fuel Substitution: Analysis of Supply-Demand Projections, Infrastructures, Investments and End-User Prices Tjandranegara, Abdul; Arsegianto, Arsegianto; Purwanto, Widodo
Makara Journal of Technology Vol 15, No 1 (2011)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v15i1.201

Abstract

The petroleum fuels (PF) subsidy has long burdens the government spending, and discourages less expensive energy usage such as natural gas (NG). Exporting NG and importing the more expensive PF products cause financial losses to Indonesia. The lack of NG infrastructure is the main hurdle in maximizing domestic NG usage and so does the perception of its high investment costs burdening government spending and pushing the NG transportation cost up. This study calculates the required NG infrastructure and its investments for several levels of PF substitutions up to 2030. To balance the NG demands, the supply from each field and its corresponding infrastructures needed was calculated and optimized using non-linear programming with generalized reduced gradient  method to calculate the lowest transportation cost for the consumers. The study shows with a favorable return on investments attractive to private investors, the NG prices can still be put much lower than PF prices, allowing subsidy, import and production cost savings in many sectors. Furthermore, the highest level of substitution scenario needs only US$ 2.07 billion a year investment, very low compare to the current US$ 14.17 billion a year PF and electricity subsidy.
The Synergy of Recombinant Xylanolytic Enzyme on Xylan Hydrolysis Asmarani, One; Wardojo, Bambang; Puspaningsih, Ni Nyoman
Makara Journal of Technology Vol 15, No 1 (2011)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v15i1.206

Abstract

Microbial xylanases or xylanolytic enzyme have received considerable attention over the last years owing to a multitude of  possible applications. These  enzymes  have  potential  in  the  biodegradation of lignocellulosic biomass  to  fuels, chemicals, fruit juice, animal feed and in improving rumen digestion. More recently, the use of xylanases as bleaching agent  in  the  pulp  and  paper  industry  has  been  suggested  to  replace  of some  of  the  chemicals  presently  used  for  this purpose. Such applications could  have an important positive impact on the environment. The purpose of  this research was  determining  the  synergy  of  3 recombinant  xylanolytic  enzymes  (β-xylosidase,  exo-xylanase  and α-L-arabinofuranosidase)  from  recombinant  Eschericia  coli  BL21 (DE-star)  in  xylan  hydrolysis  by  analysis  the  reduction sugar product. Purified of recombinant xylanolytic enzyme β-xylosidase  (Xyl), exo-xylanase  (Exo-Xyl) and α-L-arabinofuranosidase  (Abfa)  with  Ni-NTA resin.  Seven  samples  of  enzyme  (each  and  enzyme  mixture)  used to hydrolyze  xylan    substrate  (oat-spelt  xylan).  Analysis  of  hydrolysis product  was  done  by  HPLC.  The  xylanolytic activities of this enzyme before and after purification were 0,91 and 9,94 U/mL (Exo-Xyl); 1,65 and 14,2 U/mL (Xyl); 0,65  and  5,6  U/mL  (Abfa).  The  xylosidase  activity  were  2,37  and  14,3  U/mL  (Xyl);  1,49  and  10,5  U/mL  (Exo-Xyl); 2,54  and  18,6  U/mL  (Abfa).  The  highest  hydrolysis  product  of  xylan  (xylose)  shown  in  enzyme  mixture  of    exo-xylanase and β-xylosidase was 1,084 mg/mL.
Characterization of Surface Active Shell Charcoal Nyamplung Seeds (Calophyllum inophyllum Linn) Wibowo, Santiyo; Syafi, Wasrin; Pari, Gustan Pari
Makara Journal of Technology Vol 15, No 1 (2011)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v15i1.197

Abstract

Chemical and physical activation of nyamplung shell with 0%, 5%, and 10% H3PO4 for 60 and 120 minutes has been carried out to  prepare  activated  charcoal.  The  purpose  of this  experiment  was  to  look  into  the  characteristic  of  nyamplung shell activated  charcoal  surface.  Nyamplung  shell  was  carbonized  into charcoal,  then  activated  by  immersion  in  H3PO4 solution  using  0%, 5%  and  10%,  for  24  hours,  and  heated  in  retort at  two temperatures  (700 and 800 oC) and two duration (60 and 120 minutes). The material were characterized by  fourier transform infra red (FTIR), scaning electron microscope (SEM) and X-ray diffraction (XRD). The FTIR spectrum show that  activated charcoal has OH, C-H, C-O and  C=C bonds. The  bonds  of  OH  and  C-O  indicated  that  the  treatment  was produced  polar  activated  charcoal. The porous  texture  was  influenced by  H3PO4  concentration.  The  porous  with  dimension  <5 μ being predominant at low concentration of H3PO4 (0% and 5%) but larger amount of H3PO4 (10%) produced wide pore with dimension >5 μ.
Determining the Standard Value of the Oily Distortion of Acquisition the Fingerprint Images Syam, Rahmat; Hariadi, Mochamad; Purnomo, Mauridhi
Makara Journal of Technology Vol 15, No 1 (2011)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v15i1.202

Abstract

This research describes a novel procedure for determining the standard value of the oily distortion of acquisition the fingerprint images based on the score of clarity and ridge-valley thickness ratio. The fingerprint image is quantized into blocks size 32 x 32 pixels. Inside each block, an orientation line, which perpendicular to the ridge direction, is computed. The center of the block along the ridge direction, a two-dimension (2-D) vector  V1 (slanted square) with the pixel size 32 x 13 pixels can be extracted and transformed to a vertical 2-D vector V2. Linear regression can be applied to the one-dimension (1-D) vector V3 to find the determinant threshold (DT1). The lower regions than DT1 are the ridges, otherwise are the valleys. Tests carried out by calculating the clarity  of the image from the overlapping area of the gray-level distribution of ridge and valley that has been separated. Thickness ratio size of the ridge to valley, it is computation per block, the thickness of ridge and valley obtained from the gray-level values per block of image in the normal direction toward the ridge, the average values obtained from the overall image. The results shown that the standard value of the oily distortion of acquisition the fingerprint image is said to oily fingerprint when the images have local clarity scores (LCS) is between 0.01446 to 0.01550, global clarity scores (GCS) is between 0.01186 to 0.01230, and ridge-valley thickness ratio (RVTR) is between 6.98E-05 to 7.22E-05.
Formation of CaCO3 Particle and Conductivity of Na2CO3 and CaCl2 Solution Under Magnetic Field on Dynamic Fluid System Saksono, Nelson; Bismo, Setijo; Widaningroem, Roekmijati; Manaf, Azwar
Makara Journal of Technology Vol 15, No 1 (2011)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v15i1.207

Abstract

Hard  water  causes  the  CaCO3  scale  formation  on  the  pipe  walls and  heat  exchanger  equipments  in  industrial  or domestic  water  processes.  A  great  number  of  experimental  researches  on  the  prevention  of the  CaCO3  precipitation process  by  magnetic  field  have  been  carried  out.  In  this  research,  Na2CO3  and  CaCl2  solutions  was  magnetized  in  the circulated  flow  condition  (dynamic  fluid  system).  The  velocity  of  fluid  and  the  circulation  time  was  modified  to examine  its influences  to  the  magnetization  process.  CaCO3  content  was measured  by  titration  method  of  EDTA complexometry.  Conductivity  test  was  conducted  to  find  out  hydrate  ion  bonding.  The  results  showed  that magnetization increased the CaCO3 formation and the optimum process reaches for 10 minutes circulation on 0.554 m/s of flow rate. Magnetic field decreases the conductivities of Na2CO3 and CaCl2  solution, hence reduced the ion hydrate bonding. These results showed that magnetization on Na2CO3 and CaCl2 ionic solution was effective in controlling the CaCO3 formation by increasing CaCO3 precipitation.
An Investigation Into the Resistance/Powering and Seakeeping Characteristics of River Catamaran and Trimarana Murdijanto, Murdijanto; Utama, I Ketut; Jamaluddin, Andi
Makara Journal of Technology Vol 15, No 1 (2011)
Publisher : Directorate of Research and Community Services, Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7454/mst.v15i1.198

Abstract

The increase of fuel price has caused fleet operational and shipping business to be in danger situation. The fuel consumption of a ship is influenced by ship volume or wetted area which contributes directly to the increase of ship resistance and the size of main engine. In order to find out the appropriate answers, a series of investigation into river transportation using monohull, catamaran and trimaran types of vessel was carried out. The work focused on the estimation of total resistance and powering as well as seakeeping characteristics and carried out experimentally using tank test and numerically using a ship design software (Maxsurf). It was found out that the catamaran and trimaran could have less resistance and hence power compared  to monohull of similar displacement. The seakeeping characteristics of the multihull vessels were also comparable with those of the monohull. This is a good indication that river catamaran/trimaran is an efficient  and comfortable vessel. If a prototype or real vessel is developed, it can be a very efficient ship as well as a ship with high safety standard.

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