• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.890-891
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• 2011

This paper presents efficiency improvement of a universal motor used in a vacuum cleaner. The transient computation is carried out by employing finite element analysis with nonlinear material curves. Working point of magnetic field is investigated and operating frequencies are analyzed using harmonics analysis. New non-oriented electrical steel is developed for the motor regarding permeability and iron loss at the frequencies. Accordingly, new electrical steel is applied to the motor, which leads to improve efficiency of the motor.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.892-896
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• 2005

In this paper, key issues of stainless steel foil substrates for display applications have been described. We studied and analyzed technical issues on substrate passivation/planarization to control surface roughness and capacitive coupling from conductive substrates. A thick (either multiple or single) passivation/planarization layer needs to be applied on the nonelectronic-grade stainless steel substrate to provide a smooth surface and electrical insulation from the conductive substrate. Especially for large size, high-resolution display applications, low k and thick passivation/planarization layers should be used for appropriate capacitive coupling. Based on our initial study, a unit area capacitance of less than $2nF/cm^2$ of passivation/planarization layers is needed for 32" HD TV OLED displays.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.210-215
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• 2001

The ferritic 2.25CrMo steel has been used for high temperature structure applications such as turbine rotors, boilers and pressure vessels in fossil plant and petroleum chemical facilities. However, this steel is known to result in aging degradation due to temper embrittlement, carbide induced brittleness and softening of matrix after long time exposure to high temperature. This research investigated the microstructural and mechanical changes after artificial degradation treatment and evaluated the degree of degradation by several nondestructive methods. The decrease of electrical resistivity and increase of magnetic Barkhausen noise(RMS voltage) with increasing aging time were observed. The change of electrical resistivity and Barkhausen noise showed a good correlation with the ductile-brittle transition temperature.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.917-920
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• 2005

This paper introduces an optimal design technique for a 250-watt isolation transformer using a recently developed optimization method, dynamic encoding algorithm for searches(DRAS). Although the optimal design technique for transformers dates back to 1970s and local optimization is often undertaken using FEM nowadays, literature concerning global optimization of transformer cores is rarely found against its importance. In this paper, a small isolation transformer is used as a model to be optimized with application of DEAS to corresponding mathematical description. The optimization result confirms that DEAS can be successfully employed to design transformer cores for various design specifications only by changing cost functions.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.253.2-253.2
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• 2008

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.319-323
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• 1996

A new steel-making process, strip-casting, is introduced. The strip-casting is a new technique making the thin steel strip from the molten steel directly without resorting to repetitive reheating and hot-rolling required in a conventional steel-making method. This paper derives the mathematical model of strip caster, proposes a control strategy for stable startup operation and a fuzzy decision making rule for automatic control mode change in strip-casting process.

• 조명전기설비학회논문지
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• 제21권6호
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• pp.85-93
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• 2007

본 논문에서는 철심형 영구자석 선형동기전동기(PMLSM, Steel-Cored Permanent Magnet Linear Synchronous Motor)에서 운전 특성을 고려한 설계 특성 및 전략 등에 대한 내용을 다룬다. 특히 반송장치의 운송궤적에서 요구하는 동적특성과 전동기의 동적용량(Dynamic Capability)을 고려한 동적제약조건(Dynamic Constraints) 규정을 통하여, 짧은 변위의 급가감속 왕복운전을 위한 철심형 PMLSM의 최적설계 전략을 살펴본다. 이와 더불어 동특성이 두드러진 PMLSM의 설계특성으로 열적인 특성, 디텐트력 해석 및 저감, 그리고 자계의 포화특성에 대하여 추가 고찰한다.

• 한국전기전자재료학회논문지
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• 제17권2호
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• pp.190-195
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• 2004

The effect of heat treatment on torsion characteristics of high nitrogen steel wire has been studied by torsion test, tensile test, specific resistivity, X-ray diffraction and scanning electron microscopy. After heat treatment at 600∼$700^{\circ}C$, torsion cycle was increased with increasing temperature. Especially, in case of high nitrogen steel wire heat teated at $650^{\circ}C$, torsion cycle was sharply increased. It is estimated that cold worked high nitrogen steel wire started to recrystallize and phase transform at 64$0^{\circ}C$ in air atmosphere.

• International Journal of Korean Welding Society
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• 제2권1호
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• pp.1-10
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• 2002

The thermal contact conductance at different temperatures and with different electrode forces and zinc coating morphology was measured by monitoring the infrared emissions from the one dimensionally simulated contact heat transfer experiments. The contact heat transfer coefficients were presented as a function of the harmonic mean temperature of the two contacting surfaces. Using these contact heat transfer coefficients and experimentally measured temperature profiles, the electrical contact resistivities both for the faying interface and electrode-workpiece interface were deduced from the numerical analyses of the one dimension simulation welding. It was found that the average value of the contact heat transfer coefficients for the material with zinc coating (coating weight from 0 g/$mm^2$to 100 g/$mm^2$) ranges from 0.05 W/$mm^2$$^{\circ}C$ to 2.0 W/$mm^2$$^{\circ}C$ in the temperature range above 5$0^{\circ}C$ harmonic mean temperature of the two contacting surfaces. The electrical contact resistivity deduced from the one dimension simulation welding and numerical analyses showed that the ratio of electrical contact resistivity at the laying interface to the electrical contact resistivity at the electrode interface is smaller than one far both bare steel and zinc coated steel.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.262-263
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• 2005

Pt counter electrode based on flexible metal for dye-sensitized solar cells(DSCs) has been investigated. Photovoltaic structures on lightweight substrates have several advantages over the heavy glass-based structures in both terrestrial and space applications. Cyclic voltammetry and impedance spectroscopy were used to investigate electrochemical properties of Pt counter electrode both FTO glass and SUS sheet substrate. The DSCs composed of the counter electrode based on a stainless steel substrate has obtained conversion efficiencies comparable to that based on the conducting glass. The counter electrode based on the stainless steel substrate has the merit of improving the fill factor and conversion efficiency of the DSCs by reducing its internal resistance.