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IPTEK The Journal for Technology and Science

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Published by Institut Teknologi Sepuluh Nopember Surabaya

ISSN : 08534098 EISSN : 20882033 DOI : -

Core Subject : Science,

Computer Science & IT

IPTEK The Journal for Technology and Science (eISSN: 2088-2033; Print ISSN:0853-4098), is an academic journal on the issued related to natural science and technology. The journal initially published four issues every year, i.e. February, May, August, and November. From 2014, IPTEK the Journal for Technology and Science publish three times a year, they are in April, August and December in online version.

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Articles 345 Documents

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Sample Based Trip Length Distribution Quality based on χ^2 and Mean Absolute Error Value Hitapriya Suprayitno; Vita Ratnasari; Nina Saraswati; Citto Pacama Fajrinia
IPTEK The Journal for Technology and Science Vol 29, No 1 (2018)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

As a vital part of transport modelling, the trip length distribution is normally gotten from a sample. In order to get a good model, a method to test the quality of the sample based trip length distribution must be avaliable. A method to measure this quality has ever been developed, but it was found that the existing method still can be improved. While still using goodness of fit statistical test, the new method propose two quality measurements. First, to verify whether the observed trip length distribution is conforrm to the reference trip length distribution at a certain confidence level value, indicated by a value of . Second, to verify whether the error, mean absolute error measured in percentage, |e%| = 100 × |e|mean / xi,mean is acceptable. The new method can be used, while still fulfilling the basic principle of sample quality measure, i.e. satisfying maximum acceptable error at a certain confidence level.

Improvement of Preventive Maintenance Process Effectiveness in Insourcing and Outsourcing Scheme with House of Risk (HOR) Method Approach (A Case Study) Budi Siswanto; Adithya Sudiarno; Putu Dana Karningsih; Henry Pariaman
IPTEK The Journal for Technology and Science Vol 30, No 2 (2019)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Outsourcing has become the alternative scheme to gain improvement in several fields within a short time to many enterprises. One power generation in North Java implemented PM as planned maintenance strategy to maintain equipment by conducting insourcing and outsourcing scheme as PM execution. Both conditions must follow the same business process flow in PM execution process and there will occur some obstacles that interrupted PM process. The existing problem will be analyzed with House of Risk (HOR) method approach, supported by Integrated Manufacturing Open Systems Architecture (CIMOSA) process-based function modeling for identification method and Supply Chain Risk Identification System (SCRIS) risk structure identification used for mapping problem, root cause, and its relation. Analysis with HOR results in root causes that occurred within PM implementation process for both of them commonly has the same problem that is process business acknowledgment, but in outsourcing scheme not exist root cause on culture compliance and work task requirement, because they have a descriptive target to obtain service level agreement fulfillment. On both scheme still need an improving method to monitor and evaluate the PM work for better performance.

Ocean Wave Characteristics in Indonesian Waters for Sea Transportation Safety and Planning Kurniawan, Roni; Khotimah, Mia Khusnul
IPTEK The Journal for Technology and Science Vol 26, No 1 (2015)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

This study was aimed to learn about ocean wave characteristics and to identify times and areas with vulnerability to high waves in Indonesian waters. Significant wave height of Windwaves-05 model output was used to obtain such information, with surface level wind data for 11 years period (2000 to 2010) from NCEP-NOAA as the input. The model output data was then validated using multimission satellite altimeter data obtained from Aviso. Further, the data were used to identify areas of high waves based on the high waveâ€™s classification by WMO. From all of the processing results, the wave characteristics in Indonesian waters were identified, especially on ALKI (Indonesian Archipelagic Sea Lanes). Along with it, which lanes that have high potential for dangerous waves and when it occurred were identified as well. The study concluded that throughout the years, Windwaves-05 model had a magnificent performance in providing of ocean wave characteristics information in Indonesian waters. The information of height wave vulnerability needed to make a decision on the safest lanes and the best time before crossing on ALKI when the wave and its vulnerability is likely low. Throughout the years, ALKI II is the safest lanes among others since it has been identified of having lower vulnerability than others. The knowledge of the wave characteristics for a specific location is very important to design, plan and vessels operability including types of ships and shipping lanes before their activities in the sea

Bio-corrosion on Aluminium 6063 by Escherichia coli in Marine Environment Herman Pratikno; Harmin Sulistiyaning Titah
IPTEK The Journal for Technology and Science Vol 28, No 2 (2017)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Biological corrosion is caused by presence of microbes in environment. Escherichia coli causes serious biofouling in various environments and its pronounced influence on marine biofouling that causing serious problems such as accelerated corrosion. E. coli shares similar properties with most marine bacteria and it was extensively studied for marine environment. The aims of this research was to determine the corrosion rate on Aluminium 6063 by E. coli in deep seawater (salinity of 33‰), medium seawater (salinity of 35‰), shallow seawater (salinity of 37‰). Based on results, bio-corrosion rate on Al 6063 were higher than control. The bio-corrosion rate Al 6063 at day 28 in salinity of 37‰ was 1.1233 mm/year, meanwhile the corrosion rate for control was 0.7225 mm/year. Visual observation showed that corrosion occured on surface on specimen. Macrostructure observation showed that white spots occured on surface of specimen with E. coli was higher than specimen in control (without E. coli, only saline water) It was indicating that presence of E. coli caused increasing of corrosion rate on Al 6063.

Fatigue Life of Mooring Lines on External Turret Floating LNG for Different Pretension and Water Depth Norman Mahdar Sabana; Eko Budi Djatmiko; Rudi Walujo Prastianto
IPTEK The Journal for Technology and Science Vol 30, No 1 (2019)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

This paper studies fatigue life of mooring lines applied on turret-moored Floating LNG (Liquefied Natural Gas). Several case studies were designed to investigate the influence of mooring pretension and water depth on the fatigue life of mooring lines. Floating LNG with permanent external turret mooring system consists of 12 catenary lines arranged in 3 group with 4 lines each. Time domain simulation applied to calculated coupled dynamic response and mooring tension. Fatigue life is assessed using rainflow counting method, T-N curves and Palmgren-Miner rule. Analysis results for mooring pretension case show that case study 2 with lowest pretension (14%MBL) yields shortest mooring fatigue life of 1814.20 years compared to case study 1 (18%MBL) and 3 (22%MBL) with 2034.61 years and 2983.33 years respectively. Despite has the lowest dynamic line tension, case study 2 has larger tension range that results in the increased of fatigue damage. The increase in water depth will increase the mooring line length and its weight, so it results in the increase of fatigue damage. This is reflected in case study 5 (903m water depth), which has shortest mooring fatigue life of 1842.65 years compare to case study 1 (602m water depth) and 4 (301m water depth) with 2983.33 years and 3363.62 years respectively.

The Anticancer Activity of the Marine Sponge Aaptos suberitoides to Protein Profile of Fibrosarcoma Mice (Mus musculus) Noor Nailis Sa'adah; Awik Puji Dyah Nurhayati; Maya Shovitri
IPTEK The Journal for Technology and Science Vol 27, No 3 (2016)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

The study was aimed to evaluating anticancer activity of A. suberitoides on protein profile of blood plasma of fibrosarcoma mice (M. musculus). Mice were induced by Benzo(a)pyrene on the subcutaneous tissue intravenously with a concentration of 0,3 gram/0,2 oleum olivarum/day for 2 weeks. Mice were treated with ethanolic extract of A. suberitoides every day for two weeks. There were six groups. The first group (I) was control. Group II, mice were induced by CMCNa, Group III mice were treated by Cyclophosphamide. Group IV, V and VI mice were treated by ethanolic extract of A. suberitoides with 500, 1000 and 1500 mg/weight. Mice blood were taken at week fifteen. Protein profile of mice was measured by electrophoresis SDS-PAGE. The protein profile indicated that the mice were induced benzo(a)pyrene (Group II, III, IV, V and VI) have a new protein band (41 kDa). The protein band not presented in control (Group I). The protein band ( 7 kDa) was in Groups I and II, but it not presented in Groups III, IV, V and VI. The most interesting protein band was 115 kDa, which presented only in Groups II, III and IV. The research showed that the sponge extract with concentration of 1000 and 1500 mg/weight repressed the expression of protein 115 kDa

Evaluation on Expressions for Optimum Intermediate Condition of Two-Stage Vapor Compression Refrigeration Cycle Himsar Ambarita
IPTEK The Journal for Technology and Science Vol 29, No 2 (2018)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Mathematical expressions for estimating the optimum intermediate condition of two-stage vapor compression refrigeration cycle have been investigated. The objective is to evaluate the expressions for optimum intermediate condition (pressure or temperature) for maximum COP. A set of governing equations on two-stage vapor compression refrigeration cycle are developed and solved numerically. The two-stage cycle is analyzed using commonly used refrigerants for air-conditioning use, they are R12, R22, and R134a. There are six expressions for optimum intermediate condition found in literature. These expressions are divided into two group, expression for optimum pressure and expression for optimum temperature. These expressions are evaluated using the developed model. The results show that deviation of the expressions for optimum pressure can be up to 18.38%. On the other hand, the maximum deviation for optimum temperature is only 6.74%. This fact suggests that expressions for optimum temperature are better than pressure one. However, the expressions found in literature only specific for a particular refrigerant. Those can’t be used for all refrigerants.

An Investigation Into The Drag Increase on Roughen Surface due to Marine Fouling Growth A. K. Yusim; I. K. A. P. Utama
IPTEK The Journal for Technology and Science Vol 28, No 3 (2017)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Marine biofouling attached to underwater ship hull has caused problems for many years to ship operators. It has been reported to increase the total drag thus can reduce the speed of ship and disturb the overall operation of marine vehicles. Changes laminar to turbulent flow becomes fast when passing through rough ships surface. The current study models the growth of marine fouling for one year periods basis on general cargo vessel. The methods have been used in this studied was model scale 1 : 53. The use of smooth model is also included in order to analyses the difference between the two conditions. Two models of the hull roughness are regular and irregular roughness. The modeling of roughness using sand with a specific size and have been scaled. The results show that an increase in skin friction drag of about 41% per year for biofouling spread not evenly at wetted surface area (WSA).

Effect of Halide Concentration on the Effectiveness of Banana Peel Waste Inhibitor at 60C Widodo, Mochamad Puji; Tua Silaen, Yohannes Marudut; Ahada Kuswara, Muhammad Faiq Ridho; Rohmannudin, Tubagus Noor
IPTEK The Journal for Technology and Science Vol 30, No 2 (2019)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Organic inhibitors have been widely studying to be an alternative corrosion prevention because of its abundance and non-hazardous effect to the environment. One of organic inhibitors which is obtained from plant extract is banana (Musa Paradisica) peel, because it has gallocatechin which is a strong antioxidant. Otherwise, inhibition effectiveness from organic compound decreases during increasing of temperature. However, the addition of other substance like halide ion has provided multiple effect of corrosion inhibitor effectiveness. The addition of the halide ions can enhanced the inhibition efficiency of the organic inhibitors. This research highlights the effect of additional halide concentration to the inhibition effectiveness of Musa Paradisica (banana) peel on API 5 L steel in 3,5% NaCl at temperature 600C. This inhibition performance is investigated using weight loss measurement and electrochemical measurement. Result shows that the maximum inhibition efficiency was observed with the mixture of 500 ppm banana peel waaste extract and 100 ppm potassium iodide at 600C. Also, The blends behaved as mixed type inhibitor. The effectiveness was found to be in order of KI > KBr due to the larger ionic radius in iodide ion.

Estimation of Total Suspended Sediment and Chlorophyll-A Concentration from Landsat 8-Oli: The Effect of Atmospher and Retrieval Algorithm Lalu Muhamad Jaelani; Resti Limehuwey; Nia Kurniadin; Adjie Pamungkas; Eddy Setyo Koenhardono; Aries Sulisetyono
IPTEK The Journal for Technology and Science Vol 27, No 1 (2016)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Total Suspended Sediment (TSS) and Chlorophyll-a (Chl-a) are globally knows as a key parameters for regular seawater monitoring. Considering the high temporal and spatial variation of water constituent, remote sensing technique is an efficient and accurate method for extracting water physical parameter. A high accurate estimated data derived from remote sensing depends on an accurate atmospheric correction algorithm and physical parameter retrieval algorithms. In this research, we evaluated the accuracy of atmospheric corrected product of NASA as well as develop algorithms for estimating TSS and Chl-a concentration over Poteran and Gili Iyang island water using Landsat-8 OLI data. The data used in this study was collected from Poteran’s waters (9 stations) on April 22, 2015 and Gili Iyang’s waters (six stations) on October 15, 2015. Low correlation between in situ and Landsat Rrs(λ) (R2= 0.106) indicated that atmospheric correction algorithm performed by NASA has a limitation. The TSS concentration retrieval algorithm produced acceptable accuracy both over Poteran’s Waters (RE of 4.60% and R2 of 0.628) and over Gili Iyang’s waters (RE of 14.82% and R2 of 0.345). Although the R2 lower than 0.5, the relative error was more accurate than the minimum requirement of 30%. Whereas, The Chl-a concentration retrieval algorithm produced acceptable result over Poteran (RE of 13.87% and R2 of 0.416) and failed over Gili Iyang’s waters (RE of 99.140 and R2 of 0.090). The low correlation between TSS or Chl-a measured and estimated TSS or Chl-a concentration were caused not only by performance of the developed TSS and Chl-a estimation retrieval algorithm but also the effect and accuracy of atmospheric corrected reflectance of Landsat product.

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