• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.12
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• pp.72-76
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• 1996

A CMP system is newly proposed and analyzed by a home-made computer progarm. The proposed system is possibly to lower bull's eye effects such that the planarity of a wafer surface using a CMP system can be drasitcally improved. The optimum conditions for a design of the proposed system are verified using the home-made simulation program. For the proposed CMP system with a 12" diameter of platen, the optimum design conditons are the 0.09", 0.10", 0.12", and 0.14", clearance from the platern edge for wafer diameters of 5", 6", 8", and 12", respectively. These clear distance such as 0.09", 0.10", 0.12", and 0.14" are optimum lengths of the sample wafers extended ffrom the platen edge. In other words, shorter orbital lengths result in lowering of Bull's eye effects.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2001.02a
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• pp.132-135
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• 2001

Cryogenic air separation unit(ASU) was developed about 100 year ago in Europe. However, because there is not any ability of process design or manufacturing of ASU in Korea, many ASUs come from advanced countries every year. The purpose of this study is the development of cryogenic air separation unit by our own ability, especially cold box for nitrogen production. On this study, we developed the computer program for physical properties of gases and process simulation. We also did process design and manufactured of cold box, including air separation column, liquid air heat exchanger and condenser. The result of cold box test was successful.

• The KSFM Journal of Fluid Machinery
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• v.8 no.5 s.32
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• pp.22-28
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• 2005

As the water supply facilities are recently getting larger, the domestic waterworks become multi-regional water supply system. Large water supply facilities generally consist of the intake pumping station, water treatment plant and water supply/distribution facilities. Although the pumping stations and the pipeline systems are used to pump up water, it often happens pipeline damage and flooding accident by the water hammer. In this paper, the intake pumping station is guaranteed by both the computer simulation and the field test analysis. This study is contributed to the safe operation program for the pumping station in which results of the adjustment on the safety plan of the pumping station, the air valve and the valve closing time.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.1
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• pp.37-43
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• 2003

This paper proposes a soft-switching current source inverter for a photovoltaic power system. The proposed inverter has an H-type switched-capacitor module composed of two semiconductor switches, two diodes, and an LC resonant circuit. The operation of the proposed system was analyzed by a theoretical approach with equivalent circuits and was verified by computer simulations with SPICE and experimental implementation with a hardware prototype. The proposed system could be effectively applied for the power converter of photovoltaic power system interconnected with the AC power system.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2616-2619
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• 1999

The Backlight inverter used in the laptop computer is designed in this study. It has been difficult for electromagnetic transformer to enhance the efficiency and compact profile. In this study, (l) the piezoelectric transformer(PT) is used for reducing the loss: (2) the volume of core and winding coil are used in electromagnetic transformer, and (3) the zero voltage switching(ZVS) is used in the driver of the resonant circuit. The modified PT for this paper and the equivalent circuit are supported by the simulation program. ZVS is achieved by Half-Bridge inverter circuit. The result of the experiment shows more than 91% improvement in terms of the efficiency.

• Journal of electromagnetic engineering and science
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• v.9 no.4
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• pp.182-187
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• 2009

When we assign frequency resources to a new radio service, the existing services need not to be interfered with by the new service. Therefore, when we make a frequency assignment, a guard band is necessary to separate adjacent frequency bands so that both can transmit simultaneously without interfering with each other. In this paper, we propose an efficient frequency guard band decision rule for avoiding interference between radio services. The guard band is established based on the probability of interference in the previously arranged scenario. The interference probability is calculated using the spectrum engineering advanced Monte Carlo(MC) analysis tool(SEAMCAT). After applying the proposed algorithm to set up the frequency guard band, we can decide on the guard band appropriately because the result satisfies the predefined criterion.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.764-768
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• 2001

This study presents development of an software for process and die design of hot extrusion through square dies. The design of extrusion dies is still an art rather than a science with increasing complexity of shape and thinness of section. Therefore, most of the die design is still dependent on personal judgement, intuition and experience. The objective of this study is to develop an software system which includes a design rule extracted from literatures and experts in the extrusion industry. The system also includes finite element simulation program. The developed system is effectively used to design extrusion processes and dies with lead time and trial extrusion.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1735-1738
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• 2003

The dynamic design and evaluation of mechanisms need to be performed in a collaboration or concurrent system in order to shorten the development period of the product. A web-based system is the most suitable concurrent system to promote effective collaboration. In order to develop such a web-based system, Java Applet, which is not restrained by a computer's H/W and S/W, is widely used. This paper introduces a web-based 3D animation system for visualizing the motions of mechanisms. This web-based 3D animation system uses a JAVA Applet program method, which can be operated in a web-browser, and the Open Inventor for Java, which supports 3D graphics. It does not only allows the user to verify dynamic simulation results and design variables through the web, but it also has the advantage of supporting collaboration among a number of users through simultaneous connections.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.4
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• pp.578-587
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• 2009

In this paper, the characteristics of incompressible flow in a tube type marine fuel oil filter have been investigated. Fluent program has been used to obtain the solutions for the problems of three-dimensional, turbulent fuel oil flow in a filtering system. The inlet flow field is assumed to be uniform. The velocity and pressure distributions were obtained using Darcy's law. The increase of inlet velocity for cleaning fuel oil may cause some problems like vibration of the filter element. It was also required to consider the distribution of cleaning velocity because the worst distribution of cleaning velocity may cause the local insufficient cleaning effect and furthermore the effective filtration area can be reduced. The simulated results show that the computer code can be successfully applied for simulation of the complex base oil flow through the porous media. This paper could be applied to the design of auto-backwashing filtering system as design factor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.1221-1226
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• 2001

A structure gauge assessment is needed to ensure that a railway vehicle can run safely along a length of track without coming unacceptably close to lineside structures or equipment, or to vehicles running on adjacent tracks. This apparently straightforward question is in reality very complicated. The amount of space required for the safe passage of a railway vehicle is significantly greater than its static body profile for a number of reasons as follows: as the vehicle runs along the track, the track input excites the vehicle and it moves on its suspension. On curved track its geometric position leads to curve overthrows. A number of different approaches have been used to answer this question and some are described and specially applied to urban train by computer simulation in this paper. The program used for calculating the kinematic and swept envelope is the VAMPIRE made in U.K.