• 동력기계공학회지
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• 제8권2호
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• pp.53-58
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• 2004

In this paper, the semi active mount featuring Magneto rheological fluid(MR Fluid) is proposed. MR fluid is suspension of micro sized magnetizable particles in a fluid medium, and its apparent viscosity can be varied by the applied strength of magnetic field. When the controllable MR fluid is applied to mechanical devices, the devices provide simple, rapid response interfaces between electronic controls and mechanical systems. The MR fluid is applied in the conventional fluid mount for improving its performance of the mount's isolation effect. A appropriate size of the MR mount is designed and manufactured on the basis of Bingham model of MR fluid. In addition, the field dependent damping forces of MR mount are evaluated with respect to the input frequency variation.

• 대한전기학회논문지:전력기술부문A
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• 제51권9호
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• pp.451-459
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• 2002

This paper presents a method for modelling of the impedance locus in order to test the protective relay with dynamic. This paper has the two parts, the first part is the configuration of impedance locus with voltage magnitude, total impedance magnitude and angle. And the second part is the control of the locus speed with deviation of two frequencies. The proposed method is applied to two machine equivalent system with PSCAD/EMTDC to show its effectiveness.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.676-678
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• 2005

In underground power cable system, the apparent impedance at the relaying point can be changed because of the complicated configuration such as the various earth resistance and the operation of sheath voltage limiter (SVL). They have a bad effect on the distance relay operation Therefore, in this paper, in order to solve this problem, the authors are going to anly the advanced computational technique(ACI) of FR-FIS(Fuzzy Relation-based Fuzzy Inference System).

• 동력기계공학회지
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• 제21권2호
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• pp.83-88
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• 2017

We have examined the effect of values of subgrade reaction coefficient on the dynamic responses(displacement and strain responses) of the buried concrete pipeline of which the end boundary condition is the fixed ends. We have carried out the dynamic analysis of mode superposition method with representative values of coefficient of subgrade reaction applicable to the classified rock masses. We have found that the effect of subgrade reaction coefficient on the dynamic responses of the pipeline appears noticeable for the seismic waves having relatively high frequency and low apparent propagation velocity.

• 유공압시스템학회논문집
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• 제3권1호
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• pp.1-6
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• 2006

A servo actuator with a valve using MR (Magneto-Rheological) fluid is proposed for fluid control systems. The MR fluid is well known as a functional fluid whose apparent viscosity is controlled by the applied magnetic field strength. The pressure in the MR cylinder can be controlled by the applied magnetic field strength. Good points of the MR cylinder are more simple, compact and reliable structure than a conventional oil hydraulic cylinder. The experimental results show that the MR cylinder could be used as a servo actuator.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권2호
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• pp.380-383
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• 2004

We study the two storm events of 1997: one in May that was accompanied by a relativistic electron event (REE) and the other in September, with a more profound Dst decrease, but with no significant flux increase of relativistic electrons. We find that a larger amount of seed electrons was present in the May event compared to that of the September storm, whereas the ULF (ultra low frequency) power was more enhanced and the particle spectrum was harder in the September event. Hence, we demonstrate that a larger storm does not necessarily produce more seed electrons and that the amount of seed electrons is an important factor in an actual increase in REE flux levels, while ULF can harden the particle spectra without causing an apparent REE.

• 한국초전도ㆍ저온공학회논문지
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• 제13권2호
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• pp.29-32
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• 2011

The thermal properties of insulation material are essential to develop a high-temperature superconducting (HTS) power cable to be operated at around liquid nitrogen temperature. Unlike metallic materials, nonmetallic materials have a high thermal resistance; therefore special attention needs to be paid to estimate heat flow correctly. Thus, we have developed a precise instrument for measuring the thermal conductivity of insulating materials over a temperature range from 40 K to near room temperature using a cryocooler. Firstly, the measurement of thermal conductivity for Teflon is carried out for accuracy confirmation. For a supplied heat flux, the temperature difference between warm and cold side is measured in steady state, from which the thermal conductivity of Teflon is calculated and compared with published result of NIST. In addition, the apparent thermal conductivity of Polypropylene laminated paper (PPLP) is presented and its temperature dependency is discussed.

• Nuclear Engineering and Technology
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• 제5권3호
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• pp.240-248
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• 1973

고리에 위치한 원자력발전소 건설부지의 환경방사능의 측정보고이며 1970년 12월부터 1972년 11월 사이에 일광, 월내, 신암, 좌천, 소상 고리등 여섯개 지역에서 채취한 토양, 물, 솔잎, 낙진시료에 대하여 전방사능을 측정하였고 1972년에 채집한 채소류, 해산물 시료에 대하여 Sr-90 Cs-137의 방사능을 측정하였다. 각 시료의 측정처를 보면 그값은 계절적인 변화와 연차적인 감소천상을 나타내 주고 있다.

• Geomechanics and Engineering
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• 제29권3호
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• pp.259-267
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• 2022

The rheological and penetration characteristics of sodium alginate and xanthan gum aqueous solutions were analyzed for the development of biopolymer-based injection materials. The results of viscosity measurements for the rheological characteristics analysis show that all aqueous biopolymer solutions exhibit a tendency for shear-thinning, i.e., the apparent viscosity decreases as the shear rate increases. In addition, a regression analysis using several models (Power-law, Casson, Sisko, and Cross) was applied to the shear-thinning fluid analysis results, the highest accuracy was determined by applying the power-law model. The micromodel experiment for the penetration characteristics analysis determined that all biopolymer aqueous solutions show higher pore saturation than water, and that pore saturation tends to increase as the flow rate and concentration increases. When comparing the rheological and penetration characteristics of the biopolymer aqueous solution used in this study, the xanthan gum aqueous solution showed a fully developed shear-thinning tendency, unlike the sodium alginate aqueous solution. This tendency is considered to have the advantage of enhancement injectability and pore saturation.

• 한국정보전자통신기술학회논문지
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• 제10권3호
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• pp.206-212
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• 2017

본 논문은 대용량 유도전동기의 기동특성을 분석하였다. 유도전동기 토크는 전류와 자속의 곱으로서 이 자속을 발생시키기 위해서는 여자전류에 해당되는 무효전력이 필요하다. 유도전동기에 필요한 무효전력을 공급하는 방법으로 역률 보상장치를 사용하여 전원측을 대신하여 공급하는 방법을 많이 사용하는데, 역률 보상장치를 사용할 경우 피상전력을 줄일 수 있어 역률을 향상시킬 수 있다. 역률을 개선하기 위한 보상장치를 설치하는 방법으로 부하마다 설치하는 경우와 전체를 일괄 보상하는 방법으로 고압 대용량의 부하로서 일정한 운전패턴을 가지고 있는 경우에는 주로 개별보상이 주로 사용된다. 일반적으로 대용량 유도전동기는 기동 보호장치를 이용하지만 이 논문은 전전압 기동시의 특성을 분석하는 가상의 상황을 가정하여 기동특성에 대한 이론과 실제의 운전특성을 측정 분석하고 역률개선 콘덴서를 이용하여 기동특성을 개선해 보았다.