• 한국전기전자재료학회논문지
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• 제17권2호
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• pp.171-177
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• 2004

Voltage step-down characteristics in Ring/Dot type piezoelectric transformer were examined as a function of the area of input electrode when the area of output electrode is fixed. The effects of driving frequency and load resistance on the voltage step-down characteristics were also examined. Voltage gain was greatly dependent on the driving frequency and load resistance, and showed a maximum gain at resonance frequency of the step-down transformer. The frequency where the maximum cutout voltage appears increased about 0.2％ as the load resistance increased from 10 to 150 Ω. As the area of input electrode increased, the voltage gain and the efficiency of the transformer increased. Frequency dependence of efficiency of the step-down transformer revealed a similar tendency with the voltage gain curves. The maximum efficiency remarked 94% when the input voltage and the load resistance were 20 Vpp and 120 Ω, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.376-377
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• 2009

In the study the affect of $SiO_$ depending on the characteristics of break-down, we have experimented the break-down for the $SiO_$ and variable temperature change after mading nano $SiO_$ of the diameter 12 [nm] at the epoxy resin. As the experimental results, we have continued that the break-down strength is increased at the adding change but the break-down strength is decreased again as the 0.4 [wt%] standard. Also, the break-down voltage is not changed at 25, 50 [$^{\circ}C$] as the temperate change. But break-down voltage is largely changed when temperate is rising up.

• 한국추진공학회지
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• 제22권4호
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• pp.108-116
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• 2018

한국형발사체의 1단 및 2단 엔진으로 사용될 75톤급 액체로켓엔진의 연소시험이 엔진 연소시험설비에서 수행되었다. 이 엔진은 산화제로 극저온 유체인 액체산소를 사용하므로, 연소시험을 위해서는 필수적으로 설비의 공급 배관 및 엔진의 예냉과정이 진행되어 주어진 엔진 입구 온도 및 압력 요구조건이 만족되어야 한다. 따라서 향후 효율적인 시험 운용을 위해서는 시험 시 설비와 엔진에서의 예냉특성 및 예냉과정에서 소모되는 액체산소의 양을 파악하는 것이 중요하다. 이 논문에서는 75톤급 액체로켓엔진의 연소시험에서 예냉과정의 고찰을 통하여 런탱크 가압 전, 후 각 단계에서의 설비배관 및 엔진의 예냉특성을 평가하였으며, 시험 시 소모되는 액체산소의 양을 평가하였다.

• 대한기계학회논문집B
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• 제22권3호
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• pp.408-415
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• 1998

This study presents experimental results on the shut-down and start-up characteristics of a residential split-system air-conditioner with capillary tube, using R410A as a R22 alternative refrigerant. During shut-down, the transient characteristics are evaluated by measuring the high side and low side pressures and temperatures of the system. The dynamic behavior of the system after start-up is also investigated at the high temperature cooling test condition. All experiments are performed in psychrometric calorimeter. The cooling capacity, power consumption, dehumidification capacity and cycle characteristics after start-up are analyzed.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.77-82
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• 2003

In end milling process, undeformed chip thickness and cutting force vary periodically with phase change of the tool. Recently, a model has been proposed to simulate the shear and friction characteristics of an up-end milling process in terms of the equivalent oblique cutting to this. In the current study, the varying undeformed chip thickness and the cutting forces in a down-end milling process have been replaced with the equivalent ones of oblique cutting. And, the down-end milling characteristics of SM45C has been compared with that of the up-end milling previously presented with different helix angles.

• 한국전기전자재료학회논문지
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• 제14권11호
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• pp.885-891
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• 2001

Ring/dot-type step-down piezoelectric transformer was manufactured by using Pb[(Mn$\sub$1/3/Sb$\sub$2/3)$\sub$0.05/Zr$\sub$0.475/Ti$\sub$0.475/]O$_3$ ceramics, which have excellent high-power piezoelectric properties. The characteristics of step-down piezoelectric transformer as a function of load resistance at output terminal was examined. Voltage gain was greatly dependent on drive frequency and load resistance, and showed maximum voltage gain at the resonance frequency. The output voltage was linearly increased as the input voltage increased. Voltage gain of the step-down piezoelectric transformer with respect to input voltage was very stable when the load resistance was in the range of 50-500 $\Omega$ .

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.722-725
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• 2004

Voltage step-down characteristics in Ring/Dot type piezoelectric transformer were examined as a function of the area of input electrode when the area of output electrode is fixed. The effects of driving frequency and load resistance on the voltage step-down characteristics were also examined. Voltage gain was greatly dependent on the driving frequency and load resistance, and showed a maximum gain at resonance frequency of the step-down transformer. The frequency where the maximum output voltage appears increased about 0.2% as the load resistance increased from 10 to $150\Omega$. As the area of input electrode increased, the voltage gain and the efficiency of the transformer increased. Frequency dependence of efficiency of the step-down transformer revealed a similar tendency with the voltage gain curves. The maximum efficiency remarked 94% when the input voltage and the load resistance were 20 $V_{PP}$ and $120\Omega$, respectively.

• 한국구조물진단유지관리공학회 논문집
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• 제22권1호
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• pp.1-5
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• 2018

콘크리트 구조물이 점차 대형화, 고층화됨에 따라 지하구조물이 증가하고 있으며 지하실, 지하상가, 지하주차장, 지하철 등 그 종류 또한 다양해지고 있다. 이에 따라 지하구조물에 사용된 방수공법으로는 아스팔트계, 가황고무계, 점착형 시트재 등의 시트계 방수재를 이용한 외 방수공법을 주로 사용하였으나, 조인트 부분, 균열 발생 시 방수층의 파단 등 시트 방수공법의 문제점이 나타나 최근 방수층이나 외벽방수의 품질 확보와 구조물 거동에 대한 하자 발생률을 줄이고자 아스팔트 씰과 아스팔트 방수시트를 복합으로 사용하는 복합공법이 널리 사용되어 지고 있다. 그러나 일부 민간 건설 현장에서 아스팔트 씰의 누유현장으로 매스컴에 오르내리면서 아스팔트 씰의 적정품질 확보가 중요시되는 시점이다. 이에 본 연구에서는 국내에서 사용되고 있는 아스팔트 씰계 제품을 대상으로 옥외 수직부 흘러내림 특성을 평가하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.107-108
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• 2009

• 시스템엔지니어링학술지
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• 제15권2호
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• pp.39-46
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• 2019

The purpose of this paper is to present the results of the study, applying Systems Engineering(SE) method, on the feasibility of developing a Melt-down Proof Modular Micro Reactor(MDP-MMR) for its future deployment in Korea. The reactor is being developed by NCSU (North Carolina State University) due to its advantage of melt-down proof nature of the reactor core. For this paper, the characteristics of the MDP-MMR has been studied in terms of fuel characteristics, inherent safety features and passive safety system. The NCSU's development process has been reviewed applying the SE method, and further research is recommended for the feasibility study on deploying such a modular micro reactor in Korea.