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IPTEK The Journal for Technology and Science
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.
Arjuna Subject : -
Articles 5 Documents
 1 
Search results for , issue "Vol 19, No 2 (2008)" : 5 Documents clear
Converter Ac-to-Ac With Additional Free- Wheeling Switches for Improving Power Factor and Reducing Harmonic Distortion Mochamad Ashari1
IPTEK The Journal for Technology and Science Vol 19, No 2 (2008)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v19i2.153

Abstract

This paper presents development of single phase AC-to-AC converter with additional free-wheeling switches for improving the power factor and reducing harmonic distortion. The proposed system uses 2 switching types: the main switch and additional switch. The main switch is for controling the amplitude of the output voltage, while the additional switch is for releasing energy from inductive loads (free-wheeling switch). The main swicth is controlled by pulse width modulation (PWM), and the additional switch is modulated using the line frequency, 50 Hz. An AC-to-AC converter was simulated and built for laboratory test purposes. A conventional system, using thyristor and called Phase Control, was simulated for the system comparison. Results from simulation and laboratory tests show that the proposed system works properly. Using the same loads, the conventional system presents power factor as 0,34–0,71 and the voltage THD as 62.1%. The proposed system provides an improved power factor at nearly unity, and presents the total harmonic distortion of the voltage as 2.45%.
Synthesis of Nano-Sized Yag:Ce3+ by Sol- Gel Method Loli Yusastri; I. M. Joni; C. Panatarani
IPTEK The Journal for Technology and Science Vol 19, No 2 (2008)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v19i2.152

Abstract

We have been successfully synthesized YAG- :Ce3+ nanoparticle (60 nm in sized) having high crystalinity by using low temperature sol gel method. Due to additional of polyethylene glycol into the precursor source has been avoid inter particle hard-agglomeration. The influence of difference heating process on the crystallinity of YAG:Ce3+ was studied by means of XRD characterization. The highest crystallinity of YAG:Ce3+ was achieved via two step heating at 900 and 1100oC.
Structural Characterization of Tungsten Oxides Supported on Titanium Silicalite Prasetyoko, Didik; Ramli, Zainab; Endud, Salasiah; Nur, Hadi
IPTEK The Journal for Technology and Science Vol 19, No 2 (2008)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v19i2.150

Abstract

Titanium silicalite (TS-1) is known as an active material catalyst in the epoxidation reaction. In this study, tungsten oxides (WO3) with various loading amount have been supported on the TS-1 to increase of the catalytic activity of the TS-1 material. The solids structure and property were investigated by X-ray diffraction (XRD), temperature programmed reduction (TPR), ultra violet-visible diffuse reflectance (UV-Vis-DR) and infrared (IR) spectroscopy and scanning electron microscopy (SEM) techniques. The results showed that the structure of TS-1 is not collapsed after impregnation of WO3. It was also found that tungsten species have interacted with the silanol groups on the surface of TS-1.
The Potential of Using Partial Discharge Analysis for Condition Monitoring of Polymer Insulator Giriantari, I.A.D.
IPTEK The Journal for Technology and Science Vol 19, No 2 (2008)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v19i2.151

Abstract

Polymeric insulators are widely used now days due to some advantages such as compact design, light, handy and easy to install therefore less installation cost. However, polymeric insulator can be deteriorate by ageing process due to UV, severe weather, extreme temperature, humidity, and vandalism. Deterioration due to severe weather and vandalism are usually undetectable. There are many techniques have been introduced in order to detect the insulator condition, one of the technique is introduce here by using Partial Discharge analysis. Study has been done in High Voltage Lab of UNSW Australia in order to investigate the potential of using Partial Discharge Measurement technique to monitor the insulator condition. Continuous PD measurement by examining the PD patterns and behaviour of three different insulator materials that are subjected to high humidity and pollution in the small chamber has been done. PD measurement has done by utilizing Computer Discharge Analyser 3 (CDA3). PD pattern was studied and examined including its statistical distribution and its scatter plot. It was done to be able to identify the PD’s parameters that can be used for condition monitoring. Polymeric insulators were tested in clean and polluted condition. The PD signal analysis can be done in energized condition by using high frequency current transformer. The CDA3 results in particular the statistical distributions and the scatter plots have exhibited a good correlation to the change of insulator’s surface condition. PD’s statistical distributions have given quantitative data of insulator’s surface condition, whereas the scatter plots have given the qualitative data. In addition, it was also found that high frequency component of the PD’s signal spectrum occurred when the insulator’s surface has been damaged. This monitoring technique of polymeric insulator condition by using PD analysis has a great potential.
Sintering Effect on the Microstructure And Magnetic Properties of Co-Alxoy Composite Compound Sri Mulyaningsih; Setyo Purwanto; Mujamilah Mujamilah; Wisnu A. Adi; Azwar Manaf
IPTEK The Journal for Technology and Science Vol 19, No 2 (2008)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v19i2.154

Abstract

Research on sintering effect on the micro structure and the magnetic properties of composite Co-AlxOy materials has been done. The experiment was carried out by high energy milling (HEM) to refine Co and Al sample powder, followed by sintering process. The composition of sample was Co73Al27 wt% with weight ratio to the ball was 1:2.7. The milling time was varied within 4.5, 12 and 20 hours, while sintering process was conducted at 384ºC and 484ºC. Several new peaks were found after sintering process and identified as a Co-Al2O4 compound. The experiment data shows the saturation magnetization Ms value was decline for the entire sample by the sintering process. The Mr value for the 12h milling was remind stable about 9 emu/gr but, for 4.5 milling was decline from 17.5 to 9.2 and 6.2 emu/gr , while for 20h milling from 13,5 to 9.25 and 8 emu/gr. No visible changes in the microstructure are observed.

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