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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 477 Documents

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A NEW QoS GUARANTEE SLA BASED-SCHEME FOR HANDOFF CALLS IN WIRELESS NETWORKS Nguyen Cao Phuong; Tran Hong Quan; Sang-Ho Lee; Jung-Mo Moon
ASEAN Journal on Science and Technology for Development Vol. 25 No. 1 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

The most important thing is guarantee QoS over wireless infrastructures. The efficient of service level agreement (SLA) is becoming increasingly important to both service providers and customers. This paper presents some traffic control schemes for improving QoS, trafficmodel and performance evaluation are described. We are defining a new scheme for improving handoff call performances in wireless networks, a finite queuing scheme for the handoff calls. SLA measurement calculates the packet delay parameter (PD) of handoff calls. The handoff calls will be accepted into queue if their PD will be smaller than the average waiting time of the queue. Important performance measures of the suggested scheme such as the blocking probability of new call and dropping probability of handoff call are described and evaluated.

GASIFICATION STUDY OF SARAWAK COALS Nor Fadzilah Othman; Mohd Hariffin Bosrooh
ASEAN Journal on Science and Technology for Development Vol. 25 No. 1 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Thermogravimetry (TG) has been applied in a preliminary investigation, to the gasification of two low rank Sarawak coals. The coal samples, about 10 mg were investigated within the temperature range 30–900°C at different heating rate of 10, 20 and 30°C min-1, under a synthetic air atmosphere for the gasification study. The kinetic parameters were determined using Arrhenius type reaction model assuming a first-order reaction. The reactivity, RT values are fitted with Arrhenius equation at r2 = 0.83 - 0.98 for MP coal, while the RT values for MB coal are fitted with the Arrhenius equation at r2 = 0.99. The activation energy, EA for MP coal are in the range of 3.7 -4.7 kJ mol-1 and for MB coal are 7.6 - 25.6 kJ mol-1 at 3 different heating rates.

INFLUENCE OF SILICA COLLOID ON RHEOLOGY OF CEMENT PASTE WITH SUPERPLASTICIZER T.H. Chuong; P.V. Nga
ASEAN Journal on Science and Technology for Development Vol. 25 No. 1 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Information of rheological behavior of binder paste is important for proportioning high slump concrete mixture at low water to cement ratios. This paper presents experimental data on the rheological property of silica colloid incorporated binder paste using naphthalene based and polycarboxylate based superplasticizer, compared to that of silica fume incorporated binder paste. Experimental data showed that silica colloid incorporated binder is compatible to tested superplasticizers in the all investigated range of silica colloid content, whereas the pastes incorporated with high silica fume content (over 10%) indicated incompatibility, especially to naphthalene based superplasticizer. There was also found out saturated content of superplasticizer corresponding to every kind of binder and water-binder ratio, with and without set retarding admixture.

STUDY ON STRUCTURE AND CRYSTALLIZATION OF POLYPROPYLENE GRAFTED MALEIC ANHYDRIDE/NANOCLAY COMPOSITE Bui Chuong; Dang Viet Hung
ASEAN Journal on Science and Technology for Development Vol. 25 No. 1 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Nanocomposite from polypropylene grafted maleic anhydride (PP-g-MA) and nanoclay were prepared by melt proccessing in Brabender extruder. XRD analysis shows the formation of nanostructure (intercalated and exfoliated) of nanocomposite with interlayer space (d-space) increasing from 26.3Å to 30.9Å. These structures, however, do not affect the microcrystalline structure of polymer part of nanocomposite in whole. The study on nonisothermal crystallization shows the development in 3-dimentional direction of crystallites, that means spherulite form of crystalline structure.

THE EFFECT OF INNER DIAPHRAGMS AND NON-CONTINUOUS SILL SECTION ON THE STIFFNESS OF AUTOMOTIVE B-PILLAR C.F. Tan; S.A. Shamsuddin; M.H. Shafie
ASEAN Journal on Science and Technology for Development Vol. 25 No. 1 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

The paper discusses the knowledge on the behaviour of T-frame under specific loading will be obtained by experimental methods in order to investigate the deflection of the vehicle B-pillar or T-frame. In addition, a series of T-frame were designed with inner diaphragm at various location in the sill member in order to investigate the effect of inner diaphragm and noncontinuous closed hat section in the sill member. Lastly, the results from the experimental tests were compared with the finite element analysis results to demonstrate the effectiveness of the inner diaphragm in the automotive B-pillar.

STUDIES OF MONOMER IMPREGNATION AND POLYMERIZED “IN-SITU” IN WOOD USING DYNAMIC MECHANICAL THERMAL ANALYZER (DMTA) S. Hamdan; Y.L. Liew; Z.A. Talib
ASEAN Journal on Science and Technology for Development Vol. 25 No. 1 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Some tropical hardwoods (acacia mangium, madhuca utilis, dacrydium spp., dipterocarpus spp.,dyera costulata, shorea spp., shorea gibbosa, shorea macrophylla, endospermum diadenum, cratoxylum arborescens) are selected and impregnated with methyl methacrylate (MMA) and polymerized “in-situ” by using catalyst-heat technique. Treatability of the wood as determinedfrom the fractional volumetric retentions of monomer i.e. fraction of voids filled by the impregnant showed that the mean retention range from 15.03% (acacia mangium) to 56.59% (cratoxylum arborescens). The penetration of monomer evaluated using ultrasonic wave showed that the treated wood had higher velocities which indicate significant increase in density. This paper deals with the viscoelastic relaxation of polymerized treated wood. The efficiency of monomer as a plasticizer is studied through the temperature dependence of the storage modulus (E´) and loss tangent (tan d) of treated and untreated wood by dynamic mechanical thermal analysis (DMTA) over a temperature of -100 to 200ºC. E´ decrease with temperature, and as the maximum mechanical damping develop, the glass transition temperature (Tg) of plasticized wood decrease with the plasticizer content.

STUDIES ON CHITOSAN - BENZALDEHYDE INTERACTION IN A HOMOGENEOUS SYSTEM AND ITS ADSORPTION BEHAVIOR OF METAL IONS IN AQUEOUS SOLUTION Do Truong Thien; Nguyen Van Tuyen; Tran Thi Y Nhi
ASEAN Journal on Science and Technology for Development Vol. 25 No. 1 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

In this work, N-benzylidene chitosan was synthesized by chitosan –benzaldehyde interaction in a homogeneous system. The modified polymers were characterized by means of infrared (IR) spectra, X-Ray diffraction and thermal analysis. Their adsorption behavior was investigated by atomic absorption spectrophotometry. The experimental results showed that N-benzylidene chitosan had better adsorption properties and higher chemical resistance than that of chitosan.

ARSENIC AND COPPER UPTAKE BY CABBAGES GROWN ON POLLUTED SOILS Nguyen Thi Kim Phuong; Nguyen Thi Dung
ASEAN Journal on Science and Technology for Development Vol. 25 No. 1 (2008): ASEAN Journal on Science and Technology for Development (AJSTD)
Publisher : Universitas Gadjah Mada

Cabbages (Brassica Juncea (L.) Czern) were grown in pot experiments on typical unpolluted and polluted soils with concentration changing from 20.50 - 50.00 mg As/kg and 156.00 - 413.00 mg Cu/kg dry soil. The results demonstrate the elevation of As and Cu in soil may lead to increased uptake by these cabbages subsequent entry into human food chain. It was found 11.84- 32.12 mg As/kg and 46.86 - 94.47 mg Cu/kg dry leaves. It has tendency increase uptake and accumulation of Cu in cabbage tissue with increasing cultivated time, whereas, it was found accumulation of As in cabbages tissue decreased with time prolonging. The quantity of As and Cu in these cabbages, were significant higher than 0.2 mg As/kg and 5.0 mg Cu/kg fresh vegetable, the permissible limit concentration in fresh vegetable. This indicated that human may As and Cu exposure occur through eating these vegetables.

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.

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