• 한국초전도학회:학술대회논문집
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• v.10
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• pp.103-106
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• 2000

We have studied the magnetic properties in Bi$_2$Sr$_2$CaCu$_2$O$_8$ single crystal with columnar defects using micro Hall-probe array. We found that fold profiles inside sample were similar to the Bean's critical state model from the magnetic hysteresis measurement. In the magnetic relaxation measurement, the normalized relaxation rates were maximum near the center and decreased toward the edge of the sample expect zero gauss. The relaxation rates as a function of the temperature were maximum near the 40K and rapidly decreased both sides of the peak.

• Progress in Superconductivity and Cryogenics
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• v.4 no.1
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• pp.61-65
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• 2002

It becomes difficult and high in cost to construct new ducts and/or tunnels for power cables in metropolitan areas. This paper presents possible applications of an HTS superconducting power cables for transmitting electric power in metropolitan areas. Reflected were its important distinction such as compactness for installation in underground ducts and considerably high efficiency compared with present underground cables. In this paper, system modeling, transmission capacity and voltage class of compact HTS cables which should be applied to existing ducts were reviewed. Based on this, the following items on urban transmission system are examined. (1) A method of constructing a model system to introduce high temperature superconducting cables to metropolitan areas is presented. (2)The maximum outer diameter of HTS cables to be accommodated in exiting ducts is calculated based on the design standards for current cable ducts. (3)The voltage level that can be accommodated by existing ducts is examined.

• Journal of the Korean Society of Safety
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• v.10 no.1
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• pp.20-27
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• 1995

There are many methods to move or reduce the static electricity which often causes disasters in Industry, etc. The methods may Include grounding of a potentially-charged body, use of antistatic materials, humidification of an atmosphere, use of static electricity eliminators. Among those methods, the one utilizing antistatic materials is widely used in the industrial fields due to its effectiveness and inexpectiveness. In Korea, safety regulations and technical standards are not sufficient for applying to industrial fields as electrostatic disaster prevention measures due to the shortage of practically verified and reliable data. The propose of this paper is to examine the electrostatic characteristics of the antistatic materials and non-antistatic ordinary materials under the various conditions of different temperature and humidity.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.147-152
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• 2002

A new theory of thin film growth was suggested, where charged clusters of nanometer size are generated in the gas phase and are a major flux for thin films. The existence of these hypothetical clusters was experimentally confirmed in the diamond and silicon CVD processes as well as in metal evaporation. These results imply new insights as to the microstructure control of thin films. Based on this new understanding, the low temperature deposition of crystalline and amorphous silicon can be approached systematically.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.39-42
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• 2002

In this study, the computational heat transfer of the high-voltage vacuum circuit breaker was investigated. Higher normal current-ratings and stabilized thermal characteristics become more important in existing circuit breakers in order to satisfy market needs. Increases in current-ratings have an even greater effect on the Joule heating in the main circuit of the breakers. The thermal design must account for this increase in heat produced for the breaker to meet various temperature-rise limits set by industry standards. We are studying to enhance the normal current-ratings without major frame change of our present production models. As the method used in this research, we performed the computational analysis using the commercial Package, ICEPAK. We could get optimized thermal design suitable for 25% upgraded normal current-ratings through parametric study.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.04a
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• pp.290-293
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• 2008

In this study, the Computational Fluid Dynamics (CFD) has been used to analyze the smoke movement and the carbon monoxide concentration distribution, both vertically and longitudinally, in a compartment, based on conservation laws. The Fire Dynamics Simulator (FDS) developed by National Institute of Standards and Technology (NIST) was used for numerical simulations using Reynolds averaged Navier-Stokes equations (RANS) model to solve for time-averaged properties. Results show, as a function of time, a detailed distribution of temperature and carbon monoxide concentration changing against the height above the floor and those changes alongside the distance away from the fire source. Fire-induced smoke and toxic gases like CO are more dangerous in a confined space. The result of study may contribute in designing the smoke evacuation system based on the precise tenable condition.

• Journal of Fisheries and Marine Sciences Education
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• v.20 no.3
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• pp.487-499
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• 2008

This study was analyzed and assessed the environmental factors on small marine ranching sites around Gunsan Coast, West Sea of Korea. Standards of assessment are followed in the reports on the choice of marine ranching sites and regulation factors of proper site on marine artificial reefs of MOMAF. Max. current speed around Gunsan were ranged between 25.52 ~ 57.49cm/sec. These values were satisfied by comparing assessment factor such as current speed.. Factors of temperature, salinity, transparency and pH were evaluated as the proper extent. DO was not distributed as the proper extent due to different criterion. between the same assessment factor. COD, SS and nutrients were partly suited to the criteria. Especially, SS was almost higher than that of criterion. So, we are proposed to be reflected in environment characteristics of West Coast such as SS. Moreover, the extent of pollution load factors have to be specified clearly in the regulations of assessment criteria.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.3
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• pp.204-212
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• 2002

The ride comfort is one of the important dynamic performances of railway vehicle and is affected by the various factors, such as vibration, sound, temperature, humidity, etc. In general, vibration is known to be a major effect of rode comfort. There are many studies on the evaluation methods of ride comfort in the railway vehicle vibration. Each of the evaluation methods suggested by Spelling and in the standards recommends a different evaluation method and guidance. So users must review whether they can apply it to their railway system or not. In this study, we have suggested the relationship between several evaluation methods using the statistical vibration model based on the experimental data.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.209-214
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• 1994

Mono alkyl glycerides have bean obtained in good yield by enzyme catalyst from soybean oil. The reaction was carried out in an oil rich microemulsion formula. Best results were obtained with sodium bis(2-ethyl hexyl) sulfo succinate(AOT), isooctane as hydrocarbon component and buffer of pH 7. The enzyme used was a 1,3-specific lipase which leaves the 2-position intact. However, the 2-monoglyceride formed slowly undergoes long chain acyl migration to 1-mono-glyceride. Optimal reaction time at $35^{\circ}C$ reaction temperature was found to be three hour.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.244-247
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• 2002

NdBaCuO thin films were prepared on $SrTiO_{3}$ substrates by RF magnetron sputtering. These as-grown films were classified into 3type. The resistivity of the deposited films are usually lower than of the YBCO film. The Tc (onset) and Tc (R=0) in the optimized thin films are as high as 90 and 80K, respectively. These as-grown films are highly uniform and semi-trans parent and have a room temperature resistivity of $0.3m{\Omega}cm$.