• Journal of electromagnetic engineering and science
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• 제8권2호
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• pp.47-51
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• 2008

In this paper, we present a cost effective parallel-branch spiral inductor with the enhanced quality factor and the resonance frequency. This structure is designed to improve the quality factor, but different from other fully stacked spiral inductors. The parallel-branch effect is increased by overlapping the first metal below the second metal with same direction. Measurement result shows an increased quality factor of 12 % improvement. Also, we show an octagonal parallel-branch inductor which reduces the parasitic capacitances for higher frequency applications.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1996년도 추계학술대회 논문
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• pp.194-197
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• 1996

The high-strength aluminum alloy 7075-T651 was used to observe the fatigue-crack-propagation behavior for the various stress ratios with constant amplitude loading and thus to predict the fatigue life. With a chevron notch in the specimen the fatigue-crack-propagation behavior of through crack was investigated. Crack propagation behavior of through crack in the depth direction and crack growth of weldments were experimentally studied. Base material heat affected zone and weld material were considered in the fracture of weldments. The change of crack-propagation length with respect to several parameters such as stress intensity factor range(ΔK) effective stress intensity factor range(ΔKeff)ration of effective stress intensity factor range(U) stress intensity factor of crack opening point(K op) maximum stress intensity factor(K max) and number of cycles(Nf)was determined. The crack length of through crack of weldments was 2.4mm and the remaining part was a base material. The experiment was accomplished by making the crack propagate near the base material.

• 대한기계학회논문집A
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• 제20권9호
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• pp.2792-2799
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• 1996

It was shown in the previous study that the numerically derived elastic work factor for CLS specimen was independent of fiber direction for a unidirectional case. Also, it was proposed the elastic work factor could be used to determine energy release rate from a single test record. In the present study, elastic work factor was derived from a simple beam theory to investigate its dependence on material property and geometric condition. Also, the elastic work factor of CLS specimen was applied experimentally to determine critical energy release rate in order to prove its validity determining critical energy release rate from a single specimen. For this purpose, critical energy release rate determined using the elastic work factor was compared with that determined by the compliance method. The results showed that while elastic work factor is affected by $t_2/t_1$ and $L_2/L_1$ it is independent of fiber angle for a unidirectional case. It was also found that critical energy release rates determined by both methods are comparable each other, thus elastic work factor approach can be used to determine energy release rate from a single test specimen.

• 대한토목학회논문집
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• 제33권2호
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• pp.423-431
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• 2013

k-factor법은 합성교량의 설계에서 부정정 응력을 산정하는 방법으로 널리 사용되고 있다. 이 방법의 적정성을 평가하기 위하여 2경간 연속 강합성거더에 대하여 등가하중법과 비교하였다. k-factor법은 크리프에 대해서는 강재응력을 과소평가하고, 부모멘트 구간에서는 응력의 방향을 반대로 산정하며, 건조수축이나 온도차에 대해서는 단면변화를 고려하지 못하는 것을 확인하였다. 이 논문에서는 k-factor법의 정확성을 개선하면서, 계산의 편리성은 유지할 수 있는 j-factor법을 제안하였고, 그 효과를 2경간 연속 강합성거더에 적용하여 검증하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.413-416
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• 1997

In this paper, we propose a new single-stage isolated switching power supply. The proposed converter reduces the diode conduction loss and offer both the high input Power factor and the direction conversion from the ac line to a dc output voltage. This paper present the Operational principle, analysis and control and experimental results of a 100W prototype.

• 대한수학교육학회지:학교수학
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• 제18권3호
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• pp.691-709
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• 2016

수학 예비교사의 신념을 이해하는 것은 효과적인 교사교육 프로그램을 시행하고 설계하기 위하여 필수적이다. 본 연구에서는 초등 예비교사의 수학적 신념에 대해 분석하였다. 연구결과는 다음과 같다. 첫째, 수학문제해결에 대한 신념인 끈기 요인, 수학학습에 대한 신념인 교사주도 요인, 활동참여 요인, 자아개념에 대한 신념인 흥미 요인은 다른 수학적 신념요인들과 관련성이 많았다. 둘째, 수학교과에 대한 신념인 고정관념 요인이 교사주도 요인에 영향을 주고 있고, 수학문제해결에 대한 신념인 과정 요인이 활동참여 요인에 영향을 주고 있었다. 셋째, 학년별 수학적 신념 비교에서는 수학교과에 대한 신념인 고정관념, 유용성 요인과 자아개념에 대한 신념인 유익성 요인만이 통계적으로 유의미한 차이가 있었다. 넷째, 전공별 수학적 신념비교에서는 자아개념에 대한 신념인 유익성 요인과 자신감 요인을 제외한 나머지 수학적 신념에서 모두 유의미한 차이가 있었다. 본 연구결과를 토대로 초등 예비교사가 지녀야 할 수학적 신념이 무엇인지를 정립하고, 예비교사교육과정, 교수 학습 방법등 다양한 방안을 마련해야 할 것이다.

• 대한인간공학회지
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• 제12권2호
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• pp.3-13
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• 1993

A psychophysical measurement technique called "magnitude estimation" was used to evaluate several interior design alternatives for a high speed train. Pas- senger activity, seat direction, and passenger age were manipulated by using a three factor within-subjects experimental design. During the experiment, two dependent measures, a line length and a numerical estimate for each alternative design were collected to validate the experimental procedures. The results showed that pasnger seats arranged in the same direction as the running direction of the train was favored nine times more than the opposite. Also, the subjects preferred listening to music in a coach train to the other activities such as reading newspaper, watching a movie, and resting. This paper demonstrates that a psychophysical technique can be sued in the design of a development process, especially when it is difficult to quantify design variables such as subjective opinion or preference, etc.

• 아동학회지
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• 제30권2호
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• pp.161-177
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• 2009

In this study of the relationship between preschoolers' visual perception and reading Hangul words, the 287 participants showed significant developmental change in visual perception between three to five years of age. The researcher developed the computer-based screening Test of Visual Perception for Reading (TVPR). Factor analysis confirmed three factors of TVPR : perception of number, direction, and form constancy. These factors correlated highly with four factors of motor-reduced visual perception of the Korean Developmental Test of Visual Perception (Moon et al. 2003). All factors of TVPR explained reading real words and pseudo words; direction and form constancy perception predicted reading low frequency letters. These findings confirm that preschoolers' skills in visual perception contribute to the reading of words in Hangul.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권1호
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• pp.45-61
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• 2010

In the communication channel, the received signal is affected by many factors that can cause errors. These effects mean that received signal strength (RSS) based methods incur more errors in measuring distance and consequently result in low precision in the location detection process. As one of the approaches to overcome these problems, we propose using direction calibration to improve the performance of the RSS-based method for distance measurement, and sequentially a weighted least squares (WLS) method using reliability factors in conjunction with a conventional RSS weighting matrix is proposed to solve an over-determined localization process. The proposed scheme focuses on the features of the RSS method to improve the performance, and these effects are proved by the simulation results.

• 소성∙가공
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• 제15권9호
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• pp.635-640
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• 2006

Sandwich sheet with inner structure is expected to find many applications because of high stiffness to mass ratio. However, low resistance to the compressive pressure in the thickness direction is a dominating factor in the formability of sandwich sheet. In this study, sandwich sheet with pyramid type core is considered. For the compressive characteristics in the thickness direction, experiments and finite element simulations are carried out. In the experiment, deformation behavior is observed and discussed as the compression proceeds. It is shown that a corresponding finite element simulation can give a reasonable agreement with experiment in terms of maximum pressure. However, simulation shows some discrepancy from the experiment in terms of compressive pressure-displacement characteristics. The reasons for this discrepancy are studied in the geometrical imperfectness of sandwich sheet. It is also observed that most of deformation is dominated by buckling mode of pyramid legs.