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ASEAN Journal on Science and Technology for Development

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Published by Universitas Gadjah Mada

ISSN : 22249028 EISSN : 22249028 DOI : -

Core Subject : Science, Education, Engineering,

Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Computer Science & IT Mathematics

The coverage is focused on, but not limited to, the main areas of activity of ASEAN COST, namely: Biotechnology, Non-Conventional Energy Research, Materials Science and Technology, Marine Sciences, Meteorology and Geophysics, Food Science and Technology, Microelectronics and Information Technology, Space Applications, and Science and Technology Policy, Infrastructure and Resources Development.

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Articles 32 Documents

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Search results for , issue "Vol. 25 No. 2 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)" : 32 Documents clear

A STUDY ON THE EFFECT OF NOISE AND VIBRATION ON OPERATORS’ READABILITY TASK PERFORMANCE IN A MOBILE DRIVING ENVIRONMENT Iqbal Ahmed Khan; Z. Mallick; Zahid A. Khan
ASEAN Journal on Science and Technology for Development Vol. 25 No. 2 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

This paper presents a study in which the effect of noise and vibration on the task performance in a mobile driving environment is experimentally investigated. A readability kind of task, where a reading material was presented to the operators on a laptop screen was considered and the operators performed the task in a sitting posture without their back supported with the backrest of the seat. The task performance was measured in terms of mean number of characters read per minute by the operators, which served as data for statistical analysis. Results of the study showed that noise and vibration were statistically significant. The interaction between gender and vibration was also found to be significant. The presence of noise and vibration in a mobile environment decreased the operators’ task performance. The results of the simple main effect analysis indicated that the gender was statistically significant for the last two levels of vibration. However the equivalent acceleration of vibration was found statistically significant for males and females. The findings are in line with previous researches that showed negative significant effect of noise and vibration on operators’ task performance.

INTEGRATED REMOTE SENSING AND GIS FOR MODELING ECONOMIC REHABILITATION DEVELOPMENT OF EX-MINE SITES Junaidi Junaidi; Eric K.H. Goh
ASEAN Journal on Science and Technology for Development Vol. 25 No. 2 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

The potential environmental impacts of mining, increasing environmental legislation and public awareness have received increased attention world-wide in the last two decades. The focus of concern by the industry, environmental regulatory agencies and members of the public is the systematic rehabilitation of ex-mine sites to improve the quality at site for potential future commercial land use. The minerals extracted from these mine/quarry sites are essential in the construction, semiconductor, high-technology, ceramic and other manufacturing sectors for further industrial development. However, efficient engineering design and systematic economic evaluation of mine sites for site rehabilitation are required in maintaining the expected standards of environmental compliance. With escalating production costs and the keen competitiveness of the mining industry world-wide, the necessity to increase the efficiency in site rehabilitation is getting more prominence. A coordinated environmental protection and rehabilitation programme is essential if the environmental awareness of the community and the demands of the respective planning authorities are to be accommodated. There is thus a need to increase the base of knowledge for efficient planning in the systematic and progressive rehabilitation of current and future ex-mine sites. An efficient modeling tool is required for the systematic planning and design of potential economic land development of ex-mine sites. The applicability of Remote Sensing and Geographic Information System (GIS) technology is a useful tool to acquire spatial information for the systematic design and planning of potential development of ex-mine sites. This research was conducted to detect the trends in the suitability of land cover changes via land cover change detection of ex-mine sites and validated with reality. The findings are useful to assist in the development of a tool for efficient modeling and design of potential economic development of ex-mine sites. The aim of this research is to quantify, model and map the economic potential of the ex-mine sites for built up areas such as housing and other urban infrastructures. Land cover classes were interpreted into maps and the accuracy of the maps were validated to reference data and actual ground scenarios. The study for validation of the proposed modeling tool was carried out using the large prominent mining area in Malaysia namely the Kinta District. Results from the validation study carried out indicate that the correlation of the results obtained from this Integrated Remote Sensing and GIS tool for modeling to field data is in the range of 0.87-0.92 which is acceptable and close to reality.

FAULT LOCATION ON A DISTRIBUTION FEEDER USING FAULT GENERATED HIGH FREQUENCY CURRENT SIGNATURES Hashim Hizam; P.A. Crossley
ASEAN Journal on Science and Technology for Development Vol. 25 No. 2 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

This paper describes how the fault generated travelling waves detected in the current signals at a single location on a distribution feeder can be used for fault location. The method identifies the fault section and the probable location of the fault by comparing the relative distance of each “peak” in the high frequency current signals to the known reflection points in the distribution feeder. The probable fault location is then used within a transient power system simulator that models the actual network. The resulting simulated current waveforms are then cross-correlated against the original signal. If the estimated fault location is correct, the high frequency signatures in the simulated waveform will be similar to those of the measured waveforms and the cross-correlation value will be a high positive value. If the signatures differ, the cross correlation value will be negative or small. The simulation and correlation process is repeated with the next “most likely” fault location until a high degree of correlation is obtained. Simulation studies using PSCAD/EMTDC and analysis using cross-correlation suggest that this method can accurately locate a fault on a distribution feeder using measurements at a single location.

POWER SIGNAL DISTURBANCE CLASSIFICATION USING WAVELET BASED NEURAL NETWORK S. Suja; Jovitha Jerome
ASEAN Journal on Science and Technology for Development Vol. 25 No. 2 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

In this paper, the power signal disturbances are detected using discrete wavelet transform (DWT) and categorized using neural networks. This paper presents a prototype of power quality disturbance recognition system. The prototype contains three main components. First a simulator is used to generate power signal disturbances. The second component is a detector which uses the technique of DWT to detect the power signal disturbances. DWT is used to extract disturbance features in the power signal. The third component is neural network architecture to classify the power signal disturbances.

DEFORMATION OF WOOD IN COMPRESSION DURING MOISTURE MOVEMENT S. Hamdan; M.S. Osman; M.Y. Chew
ASEAN Journal on Science and Technology for Development Vol. 25 No. 2 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

This work presents the phenomenon of mechano-sorptive strain in the deformation of wood during moisture content (MC) changes. A series of experiments were designed to demonstrate the greatly enhanced deformation due to the mechano-sorptive effect. The purpose of this work is to show the magnitude of mechano-sorptive creep compared to the ordinary viscoelastic creep with applied compressive load. In order to do this, several conditions were induced. They were the moisture movement with MC change, moisture movement without MC change and conditions without moisture movement. Several apparatus were assembled to produce the desired conditions. Special care is taken to make sure that the compressive load is relatively small and is within elastic limit. This work observed the unique patterns of strains of various conditions that were induced in the experiments. The characteristics shown in the results were evaluated logically and compared to existing theories to confirm their validity. The results have shown that with the presence of mechano-sorptive, the maximum strains of Jelutong (dyera costulata) wood specimens loaded at 200N is 0.433x10 -3 . The results showed that the severest deformation is caused by the increasing MC in the wood specimen, attributed to the mechanosorptive (MS) effect.

COMPUTATION OF BEARING CAPACITY FACTOR Nq –TERZAGHI AND PRANDTL MECHANISM D.M. Dewaikar; B.G. Mohapatro; V.A. Sawant; H.S. Chore
ASEAN Journal on Science and Technology for Development Vol. 25 No. 2 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

The unique values of the bearing capacity factors, Nq are obtained in respect of failure mechanisms suggested by Terzaghi and Prandtl using limit equilibrium approach. In this paper an attempt has been made to present the analysis integrating the Kotter’s equation with Terzaghi’s and Prandtl’s mechanisms using limit equilibrium conditions. The analysis presented here with some modifications in the exiting analyses computes the bearing capacity factor – Nq , the expressions of which are similar to the one given by Terzaghi [10] and Reissner [7] who had extended the pioneering work initiated by Prandtl [6]. The analysis reported here successfully demonstrates the applicability of Kotter’s equation to the solution of limit equilibrium problems involving plane or curved failure surfaces.

EFFECTS OF Sr SUBSTITUTION ON CRYSTALLINE STRUCTURE AND RAMAN SPECTRA OF La2-xSrxNiO4+? Tran Dang Thanh; Le Van Hong
ASEAN Journal on Science and Technology for Development Vol. 25 No. 2 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Effects of Sr2+ substitution for La3+ on oxygen concentration and structure of La2-xSrxNiO4+? have been observed by X-ray diffraction and Raman scattering. Oxygen concentration and unit cell volume of the material decrease monotonously in dependence of x. The vibration modes were calculated for La2NiO4 in K2NiF4 type structure with the group symmetry of I4/mmm. The Raman active modes for this symmetry were also theoretically identified. Raman back scattering spectra have been carried out for all the ceramic polycrystalline samples at room temperature. Two Raman lines at 224.6 cm-1 and 433 cm-1 , assigned to Eg and A1g vibration modes of oxygen O(II) in bonding La/Sr-O were observed for all the samples. The lower mode 224.6 cm-1 shifts down to 208 cm-1 , whereas the upper mode 433 cm-1 shifts up when concentration of the Sr substituting for La increases.

CHARACTERISTICS OF LITHIUM LANTHANUM TITANATE THIN FILMS MADE BY ELECTRON BEAM EVAPORATION FROM NANOSTRUCTURED La0.67-xLi 3xTiO3 TARGET Nguyen Nang Dinh; Le Dinh Trong; Pham Duy Long
ASEAN Journal on Science and Technology for Development Vol. 25 No. 2 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Bulk nanostructured perovskites of La0.67-xLi3xTiO3 (LLTO) were prepared by using thermally ball-grinding from compounds of La2O3, Li2CO3 and TiO2. From XRD analysis, it was found that LTTO materials were crystallized with nano-size grains of an average size of 30 nm. The bulk ionic conductivity was found strongly dependent on the Li+ composition, the samples with x = 0.11 (corresponding to a La0.56Li0.33TiO3 compound) have the best ionic conductivity, which is ca. 3.2 x 10-3 S/cm at room temperature. The LLTO amorphous films were made by electron beam deposition. At room temperature the smooth films have ionic conductivity of 3.5 x 10-5 S/cm and transmittance of 80%. The optical bandgap of the films was found to be of 2.3 eV. The results have shown that the perovskite La0.56Li0.33TiO3 thin films can be used for a transparent solid electrolyte in ionic battery and in all-solid-state electrochromic devices, in particular.

ELECTROCHEMICAL PERFORMANCES AND CORROSION INHIBITION OF AA6061 IN TROPICAL SEAWATER R. Rosliza; H.B. Senin; W.B. Wan Nik
ASEAN Journal on Science and Technology for Development Vol. 25 No. 2 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

The corrosion performances of AA6061 aluminum alloy in tropical seawater was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and their morphology was characterized by the scanning electron microscopy (SEM). The results showed that the presence of sodium benzoate as an inhibitor significantly decrease the corrosion current densities (i corr ), corrosion rates and double layer capacitance (C dl ), whilst increasing the polarization resistance (R p ). The scanning electron microscopy (SEM) images indicated that the mechanism of charge transfer and the formation of thin film have been taken place on the specimens.

NUMERICAL RESULT FOR VARIATIONAL INEQUALITY PROBLEMS WITH EQUALITY CONSTRAINT Pham Van Loi
ASEAN Journal on Science and Technology for Development Vol. 25 No. 2 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

In this paper we present some numerical results for illustrating a theoret- ical results obtained in our investigation in the field of variational inequality problems with constraint in the form of operator equation involving monotone operator.

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