• 한국분무공학회지
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• 제11권3호
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• pp.155-160
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• 2006

Spray characteristics of charge injected 2-fluid nozzle for non-conducting liquid have been studied. Spray current, specific charge and SMD of diesel have been measured. Spray current and specific charge are proportional to applied voltage. Air flow did not effect on spray current and specific charge. SMD decreases as air flow rate increases and decreases as applied voltage increases additionally. Spray angle increases as applied voltage increases. Fine droplets are obtained by charge injected 2-fluid nozzle without charge loss.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 12th Asian Congress of Fluid Mechanics
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• pp.40.2-40.2
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• 2008

• 조명전기설비학회논문지
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• 제12권3호
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• pp.89-98
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• 1998

본 논문에서는 도체를 비파괴적으로 검사하기 위한 솔레노이드 와전류 코일의 몇가지 해석적인 결과가 다루어진다. 원통형 도체관이나 2-도체를 가진 솔레노이드 코일의 규격화 임피던스가 해석된다. 도체의 도전율, 투자율과 전원주파수와 같은 전기.자기적 성질과 충전율이나 반경비의 기하학적 성질 역시 규명되었다. 수치해석에 의해 구한 모델의 임피던스 특성들이 검토되고, 비자성 도체관과 2-도체의 몇가지 시료들올 사용하여 모델의 타당성이 검증되었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.113-118
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• 1997

A new approach to process optimal design in non-isothermal, non-steady state metal forming is presented. In this approach, the optimal design problem is formulated on the basis of the integrated thermo-mechanical finite element process model so as to cover a wide range of the objective functions and design variables, and the derivative based approach is adopted for conducting optimization by design iteration. The process model, the formulation for process optimal design, and the procedures for the evaluation of the design sensitivity and for design iteration for optimization are described.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.483-488
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• 2003

Frictional heating in brakes causes thermoelastic distortion of the contacting bodies and hence affects the contact pressure distribution. The resulting thermo-mechanical coupling can cause thermoelastic instability (TEI) if the sliding speed is sufficiently high, leading to non-uniform heating called hot spots and low frequency vibration known as hot judder. The vibration of brakes to the known phenomenon of frictionally-excited thermoelastic instability is estimated studying the interface temperature and pressure evolution with time. A simple model has been considered where a layer with half-thickness ${\alpha}$ slides with speed V between two half-planes which are rigid and non-conducting. The advantage of this properly simple model permits us to deduce analytically the critical conditions for the onset of instability, which is the relation between the critical speed and the growth rate of the interface temperature and pressure. Symmetrical component of pressure and temperature distribution at the layer interfaces can be more unstable than antisymmetrical component. As the thickness ${\alpha}$ reduces, the system becomes more apt to thermoelastic instability. Moreover, the evolution of the system beyond the critical conditions has shown that even if low frequency perturbations are associated with low critical speed, it might be less critical than high frequency perturbations if the working sliding speed is much larger than the actual critical speed of the system.

• 한국자동차공학회논문집
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• 제12권1호
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• pp.114-121
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• 2004

Frictional heating in brakes causes thermoelastic distortion of the contacting bodies and hence affects the contact pressure distribution. The resulting thermo-mechanical coupling can cause thermoelastic instability (TEI) if the sliding speed is sufficiently high, leading to non-uniform heating called hot spots and low frequency vibration known as hot judder. The vibration of brakes to the known phenomenon of frictionally-excited thermoelastic instability is estimated studying the interface temperature and pressure evolution with time. A simple model has been considered where a layer with half-thickness$\alpha$slides with speed V between two half-planes which are rigid and non-conducting. The advantage of this properlysimple model permits us to deduce analytically the critical conditions for the onset of instability, which is the relation between the critical speed and the growth rate of the interface temperature and pressure. Symmetrical component of pressure and temperature distribution at the layer interfaces can be more unstable than antisymmetrical component. As the thickness $\alpha$ reduces, the system becomes more apt to thermoelastic instability. For perturbations with wave number smaller than the critical$m_{cr}$ the temperature increases with m vice versa for perturbations with wave number larges than $m_{cr}$ , the temperature decreases with m.

• 한국전기전자재료학회논문지
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• 제24권6호
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• pp.504-509
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• 2011

The conducting current of non-uniform plasma immersed electrode consists of ion current and secondary electron emission current caused by the impinging ion current. The ion current is determined by the ion dose passing through the sheath in front of electrode and the ion distribution in front of the electrode plays an important role in the secondary electron emission. The investigation of the distributed plasma and secondary electron effect on electrode ion current was carried out as the stainless steel electrode plugged with quartz tube was immersed in the inductively coupled Ar plasma using the antenna powered by 1 kw and the density profile was measured. After that, the negative voltage was applied by 1 kV~6 kV to measure the conduction current for the analysis of ion current.

• Journal of Electrical Engineering and Technology
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• 제8권2호
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• pp.364-370
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• 2013

In the current paper, we propose a new modeling algorithm to analyze the coupling between an incident electromagnetic field (EMF) and a twisted conducting line, which is a kind of non-uniform line. Typically, analysis of external field coupling to a uniform transmission line (TL) is implemented by the Baum-Liu-Tesche (BLT) equation so that the induced load responses can be obtained. However, it is difficult to apply this method to the analysis of a twisted conducting line. To overcome this limitation, we used a chain matrix composed of ABCD parameters. The proposed algorithm expands the dimension of the previous chain matrix to consider the EMF coupling effectiveness of each twisted pair, which is then applied to multi-conductor transmission line (MTL) theory. In addition, we included a comparative study that involves the results of each method applied in the conventional BLT equation and new proposed algorithm in the uniform two-wire TL case to verify the proposed method.

• 창의정보문화연구
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• 제7권4호
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• pp.207-215
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• 2021

컴퓨팅 사고력이 세계적으로 중요한 역량으로 주목받으면서 2015 개정 교육과정에서 SW 교육이 도입되었으며, 2018년부터 교육과정에 SW 교육이 적용되었다. 하지만 열악한 교육 환경에 있는 교육 소외계층은 SW 교육의 사각지대에 있으며, 체계적인 SW 교육을 받지 못하는 실정이다. 이에 본 연구는 코로나-19 집단 감염병을 통해 비대면 온라인 교육이 진행되고 있는 시점에서, 267명의 교육 소외계층 초등학생을 대상으로 비대면 SW 온라인 교육 프로그램을 시행하여 그 효과를 분석하였다. 추상화, 문제분해, 알고리즘, 자동화, 데이터 처리의 요소로 구성된 컴퓨팅 사고력 검사를 교육 전과 후에 실시한 결과 컴퓨팅 사고력 전체 점수와 다섯가지 모든 요소의 점수가 통계적으로 유의미하게 높아졌다(p<0.001). 다섯 가지 요소 중에서는 데이터 처리 점수에서 가장 높은 점수의 향상이 있었다. 이러한 결과는 비대면 SW 온라인 교육 프로그램이 교육 소외계층 초등학생들의 컴퓨팅 사고력 향상에 효과가 있음을 시사한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.617-620
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• 1998

In this paper we realized non-contact sheet resistance measurement system using eddy current. Proposed system is designed to meet the requirements which is necessary when dealing with conducting thin films on large area LCD panel. With several metals we could get lift-off curves which has the same trend as in principal. Especially in the region of high conductivity this system has more discriminating ability than 4-point probe system.