• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.1135-1138
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• 2003

The transformer is major equipment in power receiving and substation facilities. Necessary conditions required for the transformer are compactness, lightness, high reliability, economic advantages, and easy maintenance. The pole-mount transformer installed in distribution system is acting direct role in supply of electric power and it is electric power device should drive for long term. Most of modem transformer are oil-filled transformer and accident is happening considerable. The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss. One body molding transformer needs some cooling method because heat radiation between each winding is difficult. In this paper, The thermal analysis of pole mount mold transformer with one body molding by duct condition is investigated and the test result of temperature rise is compared with simulation data.

• Journal of Magnetics
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• 제13권2호
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• pp.37-42
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• 2008

In this paper, design parameters of high Q (> 50), high current inductor for on-chip power module were optimized by 4 Xs 3 Ys DOE (Design of Experiment). Coil spacing, coil thickness, ferrite thickness, and permeability were assigned to Xs, and inductance (L) and Q factor at 10 MHz, and resonance frequency ($f_r$) were determined Ys. Effects of each X on the Ys were demonstrated and explained using known inductor theory. Multiple response optimizations were accomplished by three derived regression equations on the Ys. As a result, L of 125 nH, Q factor of 197.5, and $f_r$ of 316.3 MHz were obtained with coil space of $127\;{\mu}m$, Cu thickness of $67.8\;{\mu}m$, ferrite thickness of $130.3\;{\mu}m$, and permeability 156.5. Loss tan ${\delta}=0$ was assumed for the estimation. Accordingly, Q factor of about 60 is expected at tan ${\delta}=0.02$.

• 한국초전도ㆍ저온공학회논문지
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• 제14권2호
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• pp.12-15
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• 2012

This paper presents simulation and small-scale experimental tests of a fault current controller. Smart fault controller as proposed and proven conceptually in our previous work is promising technology for the smart power grid where distributed and even stochastic generation sources are prevalent and grid operations are more dynamic. Existing protection schemes simply limiting the fault current to the pre-determined set values may not show best performance and even lead to coordination failures, potentially leading to catastrophic failure. Thus, this paper designs fault current controller with a full bridge thyristor rectifier, embedding a superconducting coil for which the controller is electrically invisible during normal operation because the loss due to the coil is near-zero. When a fault occurs and the resulting current through the superconducting coil exceeds a certain value set intelligently based on the current operating condition of the grid, the magnitude of the fault current is controlled to this desired value by adjusting the firing angles of thyristors such that the overall system integrity is successfully maintained. Detailed time-domain simulations are performed and lab-scale testing circuits are built to demonstrate the desired functionality and efficacy of the proposed fault current controller.

• 한국초전도ㆍ저온공학회논문지
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• 제13권1호
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• pp.17-21
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• 2011

A hybrid superconducting fault current limiter (SFCL) with fast switch had been previously suggested by our research group. To make a hybrid SFCL, different superconducting wires were wound two pancake coils so that two pancake coils had asymmetric configuration. The impedance of the asymmetric non-inductive coils are zero with applied normal current. However during the fault. currents were distributed unequally into the two pancake coils because each superconducting wires have different electrical characteristics. This unequal distribution of current causes effective magnetic flux which generate repulsive force. Fast switch was thus opened by the force applied to the aluminum plate which consists of SFCL. In this paper, the AC loss characteristics of the asymmetric non-inductive coils with combinations of superconducting wires were studied and calculated by related experiments and finite element method (FEM) simulation. From these results, we suggested the appropriate combination of two superconducting wires to be used for the asymmetric non-inductive coils.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.705-706
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• 2008

There has been, in recent years, effort to make cast copper rotors for industrial use of induction motors. Because the incorporation of copper for the conductor bars and end rings of the induction motor in place of aluminum would result in attractive improvements in motor energy efficiency. The purpose of this method is a reducing the copper loss as using higher conductivity of copper. In this paper as the single phase induction motor is studied, the stator slots and coil turn number is designed for adjusting the slot fill factor and improving its efficiency. At this time design is basis on calculation of reducing loss. And finally this paper shows that the before and after result is compared and analyzed.

• Nuclear Engineering and Technology
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• 제45권3호
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• pp.347-360
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• 2013

This paper presents an experimental investigation of the small-break loss-of-coolant accident (SBLOCA) and the loss-of-feedwater accident (LOFW) in a scaled integral test facility of REX-10. REX-10 is a small integral-type PWR in which the coolant flow is driven by natural circulation, and the RCS is pressurized by the steam-gas pressurizer. The postulated accidents of REX-10 include the system depressurization initiated by the break of a nitrogen injection line connected to the steam-gas pressurizer and the complete loss of normal feedwater flow by the malfunction of control systems. The integral effect tests on SBLOCA and LOFW are conducted at the REX-10 Test Facility (RTF), a full-height full-pressure facility with reduced power by 1/50. The SBLOCA experiment is initiated by opening a flow passage out of the pressurizer vessel, and the LOFW experiment begins with the termination of the feedwater supply into the helical-coil steam generator. The experimental results reveal that the RTF can assure sufficient cooldown capability with the simulated PRHRS flow during these DBAs. In particular, the RTF exhibits faster pressurization during the LOFW test when employing the steam-gas pressurizer than the steam pressurizer. This experimental study can provide unique data to validate the thermal-hydraulic analysis code for REX-10.

• 대한치과교정학회지
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• 제38권6호
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• pp.376-387
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• 2008

본 연구의 목적은 pendulum 장치, 미니임플란트를 동반한 pendulum장치(펜듈럼), 오픈코일 스프링 및 미니임플란트를 동반한 오픈코일 스프링 이용 시 각각의 치아이동 양상을 3차원적으로 분석하는 데 있었다. 상악 좌측 치조골 및 치아 모형을 제작하고, Calorific $machine^{(R)}$을 이용하여 모형상에서 대구치를 3 mm 원심 이동시켰다. 실험은 5회씩 반복 실시하였다. 모델을 전산화 단층 촬영한 후 V-$Works^{TM}$를 이용하여 3차원 모델을 제작하였다. $Rapidform^{TM}$상에서 3차원적으로 이동방향과 이동량을 계측하였고, 각각의 장치에 관한 통계적 유의성을 검정하였다. 교정용 미니임플란트를 간접 골성 고정원으로 이용하여 오픈코일 스프링으로 구치부를 원심으로 이동시켰을 때가 치체이동에 가장 가까운 이동양상을 보였고, 고정원 소실도 적게 나타났다 (p < 0.05). 오픈코일 스프링, 펜듈럼 장치 모두 미니임플란트를 부가적으로 이용했을 때 고정원 소실량이 적었다 (p < 0.05). 미니임플란트를 이용하지 않은 경우에는 두 장치의 고정원 소실량이 비슷하였다. 미니임플란트의 이용 여부와 관계없이 펜듈럼 장치로 상악 구치 원심 이동 시 오픈코일 스프링에 비해 제1대구치가 조절성 경사이동 양상으로 이동되었고 (p < 0.05), 제2대구치는 비조절성 경사이동 양상을 보였으며, 치관의 협측경사이동이 일어났다 (p < 0.05). 이와 같은 결과를 근거로 간접 골성 고정원을 이용한 오픈코일 스프링이 상악 구치의 원심 치체이동에 가장 효과적인 장치였으며, 펜듈럼 장치를 이용한 구치부 원심이동 시에는 추가적인 조절이 필요하다고 할 수 있다.

• 센서학회지
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• 제9권6호
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• pp.404-415
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• 2000

본 논문에서는 산불에 의한 가공송전선의 열화에 대한 몇 가지 특성들과 비파괴 검사를 다룬다. 노화된 ACSR 도체에 대한 대기부식과 전해부식과 같은 부식기구를 설명한 후에 부식검출에 대해서 기술한다. 솔레노이드 코일의 임피던스 해석을 통하여 와류센서가 도체의 싱한 결함과 국부부식을 검사하는데 유용하게 사용될 수 있음을 확인하였다. 시험 도체를 코일 내부에 삽입한 경우에 센서코일의 임피던스가 변하므로, 산불에 의해 초래된 열화 정도를 측정하는 것이 가능하였다. 인공화염에 의해 열화 된 몇 개의 시료들을 사용하여 인장강도, 신장율과 센서 임피던스가 측정되었다. 화염 기간을 어느 정도 증가시키면, 알루미늄 소선의 인장은 현저하게 감소하기 시작하나 아연도금 강소선은 약간의 아연층이 부식되지만 인장은 초기와 유사하게 유지하였다. 일반적으로 도체의 인장하중이 감소하고 반대로 신장율이 증가하면 센서 임피던스는 감소하는 것을 알 수 있었다. 따라서, 센서의 출력은 도체의 기계적 특성 변화를 나타내므로 이 센서는 산등성이에 가설된 ACSR 도체에 대해 산불로 인한 열화상태를 검출하는데 이용할 수 있다. 결국, 산불에 의한 심한 열화상태에 대한 중요한 정보를 얻는데 솔레노이드 코일을 응용할 수 있다는 것을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.923-925
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• 2002

The existing contactless inductive coupler has many problems because of its large volume and high level of exciting current, so a new contactless inductive coupler is being required under the circumstances and the load requirement. For a contactless inductive coupler in the manufacturing equipment of semiconductor, the coupler's efficiency is low because of its small magnetic inductance and large leakage inductance. Moreover, the high frequency switching to increase energy density per unit volume increases the iron loss and the eddy current loss, so it must be considered deeply when selecting core materials. Therefore, this paper presents core materials and shape to improve the performance of the contactless inductive coupler according to the coil positions.

• Journal of Magnetics
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• 제17권1호
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• pp.36-41
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• 2012

The transcranial magnetic stimulation recharges the energy storing condenser, and sends the stored energy in the condenser to the pulse shaping circuit, which then delivers it to the stimulating coil. The previous types of transcranial magnetic stimulation required a booster transformer, secondary rectifier for high voltages and a condenser for smooth type. The energy storing condenser is recharged by switching the high-voltage direct current power. Loss occurs due to the resistance in the recharging circuit, and the single-pulse output energy in the transcranial magnetic stimulation can be changed because the recharging voltage cannot be adjusted. In this study a booster transformer, which decreases the volume and weight, was not used. Instead, a current resonance inverter was applied to cut down the switching loss. A transcranial magnetic stimulation, which can simultaneously alter the recharging voltage and pulse repeats, was used to examine the output characteristics.