• Proceedings of the KOSOMBE Conference
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• v.1994 no.05
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• pp.111-114
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• 1994

Three component velocity measurements with a refractive index-matching technique was used to investigate the flow characteristics in the atrio-pulmomnary (AP) Fontan connection under the steady flow condition. A strong swirl was observed in the extra-cardiac conduit and the main pulmonary artery (MPA). Maximum velocity magnitude in the MPA was about 0.8 m/s near the posterior wall at 6 liter/min. Swirling motion of the flow as well as geometric abnormalities of the connection are important factors in energy loss across Fontan connections.

• Journal of Sensor Science and Technology
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• v.5 no.5
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• pp.85-95
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• 1996

Based on the transmission of coupled gap solitons in nonlinear periodic media, we present an all-optical switching scheme which has a novel architecture and principle. The proposed switch with an extremely small switching element can be realized on a semiconductor waveguide. We here investigate the switching performance with a GaAs waveguide in order to give criteria for the experimental realization of the all-optical switching phenomena. We also suggest a variation of an index-matching scheme to solve the technical problem such as the input-energy coupling into a periodic waveguide.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1316-1318
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• 2002

A methodology for reliability and economic analysis of wind embedded electric power system is presented in this paper. This is done by evaluating the reliability index, loss of load expectation (LOLE), for the power system with and without integration of wind system in the overall electric power system. Economic analysis of the wind energy embedded electric system is done in terms of conventional fuel saving assessment due to the use of wind power generation units.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.206-207
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• 2009

PECVD를 이용하여 상온에서 Silicon nitride 박막을 제조하였다. 그리고 증착 중에 non-invasive ion energy analyzer를 이용하여 이온에너지와 이온에너지 flux룰 측정하였다. PECVD의 소스 파워는 500W, 바이어스 파워 100W으로 고정하고 주파수 250Hz으로 고정된 상태에서 펄스를 인가하여 duty ratio를 30-100%까지 변화시켰다. 작은 duty ratio 범위 (30-70%)에서 duty ratio가 감소할 때, 이온에너지와 이온에너지의 비가 감소하였다. 이 때 감소되는 굴절률은 저이온에너지 변수와 강한 연관성을 지니고 있었다. 굴절률은 1.65-2.46 사이에서 변화하였다.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.87.1-87.1
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• 2013

Ellerman bombs(EB) are small-scale bright features observed best in the wings of H alpha line. We used the Fast Imaging Solar Spectrograph(FISS) with the 1.6m New Solar Telescope at Big Bear Solar Observatory, in order to investigate characteristics of each EB. We analyzed H alpha line profiles of EBs, and classified EBs by their contrast profiles. To analyse characteristics of EBs, we applied power-law fitting ($C={\alpha}{\Delta}{\lambda}^{-n}$) to the EB contrast profiles. The amplitude ${\alpha}$ is a measure of the strength of an EB event (or the amount of released energy), and the power-law index n is a measure of spatial concentration of energy in the higher layers of the solar atmosphere. With the two parameters, we classified EBs into a few groups. We try to understand the physical properties of each group.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2000.11a
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• pp.121-126
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• 2000

국내 원자력발전은 전체 전력공급의 40%이상을 차지하고 있으면서도 그 특성상 기저부하용으로만 사용되고 있다. 그러나 전기에너지의 효율적인 이용과 다양한 전력수요에 능동적으로 대처할 수 있도록 원전의 부하추종운전 능력이 더욱 중요하게 인식되고 있는 상황이다. G7과제의 하나인 차세대원자로(Korean Next Generation Reactor, KNGR)는 기본적인 요건으로 부하추종운전 능력을 갖도록 개발되고 있다. 여기에서는 기존에 개발된 부하추종운전 제어논리를 변경된 부하추종운전 기본요건에 맞도록 하고, 구동 제어군 특성의 극대화 및 온도불감대 출력분포 제어논리 등을 개선시킴으로써 주기초 및 주기중 뿐만아니라 90% 주기말에서도 ASI(Axial Shape Index)가 만족스럽게 제어됨을 확인하였다.

• Journal of Energy Engineering
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• v.11 no.4
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• pp.359-369
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• 2002

Nuclear power plant is a huge system with multidisciplinary technology. So, R & D prioritization is a not a simple task and the relative importance of each prioritization criterion is not well established. This study built a technology classification chart for nuclear power plant operation and maintenace, established the relative importance of prioritization criteria and assigned the relative importance of each technology at each level. Analytical Hierarchy Process was used for the prioritization and the result was validated with Consistency Index and outcomes of fields interview.

• Transactions on Electrical and Electronic Materials
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• v.15 no.6
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• pp.305-308
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• 2014

Organosilyl-modified and star-shaped poly (${\varepsilon}$-caprolactone) (m-PCL) was prepared, and added to polymethylsilsesquioxane (PMSSQ), to make composites. The end groups of m-PCL are chemically similar to PMSSQ, and m-PCL mixed well with PMSSQ in the composite. Porous PMSSQ film was made by further calcination of the composite film at elevated temperature. m-PCL-templated PMSSQ and the as-prepared porous PMSSQ were structurally, optically, and thermally characterized in thin films. The chemical binding of m-PCL and PMSSQ effectively suppressed the phase separation of PMSSQ and m-PCL during the curing process. After calcination at elevated temperature, there remained many pores in the PMSSQ matrix. The refractive indices of the resulting porous PMSSQ thin films decreased with increase of the film porosities, depending on the initial m-PCL loadings.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.447-449
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• 1994

This paper deals with the static characteristics of filters at the AC source in single phase PWM converter using hysterisis current control method. The filters are needed to reduce the current harmonics. In general, there are two kinds of filters which can be used for current controlled PWM converter. One is the low pass filter, the other is the resonant filter for a frequency. This paper designs these filters by analysing the characteristics. And these filters are compared through performance index such as harmonic reduction factor and the value of components which make up filters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.7
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• pp.1095-1099
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• 2002

We experimentally investigate the evolution of nanosecond Stokes pulses in a single-pass Raman laser pumped by a Q-switched Nd:YAG laser at 1064 na As a Raman medium, a GeO2-doped graded-index multimode fiber ot 220 m long Is used. We demonstrate that efficient generation of several Stokes components with 1.5∼2.7 nanosecond pulsewidth is obtained by varying the input pump energy.