• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 제3회 금형가공 심포지엄
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• pp.71-78
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• 2004

Most of member parts have experienced severe springback problems because of their open shape Now it becomes imperative to develop an effective method, which can resolve these problems. However, there remain several obstacles to get accurate estimation of shape error. In analysis, we have to analyze the total process including forming, trimming and flanging. Furthermore, it is another challenge to compare the computed result with the real shape. In this study we developed an analysis program for the springback analysis. We could achive a big enhancement in computation time in springback analysis by using latest equation solving technique and could get a more robust solution conversence by contination method. We have approached this problem in two steps. In the first step, we analyzed forming stage to solve tearing and wrinkling problems. In the second step, we have analyzed full process and have done springback analysis with the same boundary condition as field measuring conditions. We have investigated the accuracy of springback analysis in terms of gap and flush used for insfection of real autobody panels. We found good and effective agreement with the observed results.

• Asian Journal of Business Environment
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• 제6권2호
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• pp.27-32
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• 2016

Purpose - This paper aims to analyze and investigate to find out the appropriate ways to make an easy TBT of smart city. It is an important issue between Korea and China because TBT of smart city has lots of advantages in IT, S/W, IOT, and Home network. Research design, data and methodology - First, the paper made use of reviewing2nd data analysis and focused on group interview, and then compared with analysis on the international rule and system such as smart city system, technical regulation, and standard through test certification procedure and inspection. Second, this paper reviewed electric/electronic test, certification, and calibration. Third, through analyzing MRA between Korea and china, the paper focused on SDoC, Mutual Acceptance of International certification, and IECCB scheme. Results - Through the comparison and analysis, this paper found that it is important to promote multi-track agreements with the countries that need short-term promotion. Moreover, it is necessary to conclude an agreement with the leading countries in Middle East and Central America. Conclusions - Through the above the reviews and analysis, we can see the importance of promotion in FTA and MRA with the efforts to remove the obstacles and promote to make an easy TBT by MRA between Korea and China.

• 설비공학논문집
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• 제23권10호
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• pp.639-645
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• 2011

The object of this study is to analyze and evaluate outdoor wind pressure effect in a high-rise residential building when seasonal wind blow on coast area. The target building consists of 3 tower buildings over 250m in height. For the evaluation of the outdoor wind effect, CFD simulation was performed. The results of the simulations are as follows : 1) In that case of high-rise building, horizontal stream is more affected than vertical stream. 2) In case of summer season northeasterly wind, building pressure distributions are unstable and surface pressures of outside are effected respectively. 3) In case of winter season westerly wind, building preassure differentiations are not so much because of screening effects of the B, and the C buildings. 4) In case of winter season northwesterly wind, front wind affects on the A building directly because of no obstacles.

• 한국수학교육학회:학술대회논문집
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• 한국수학교육학회 2007년도 제38회 전국수학교육연구대회 프로시딩
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• pp.7-19
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• 2007

During the past 20 years, a small but potentially powerful initiative has established itself in the mathematics education landscape: Mathematics Across the Curriculum (MAC). This curricular reform movement was designed to address a serious problem: Not only are students unable to demonstrate understanding of mathematical ideas and their applications, but also they harbor misconceptions about the meaning and purpose of mathematics. This paper chronicles the brief history of the MaC movement. The sections of the paper correspond loosely tn the typical steps one might take to solve a mathematics problem. The Problem Takes Shape presents a discussion of the social and economic forces that led to the need for increased articulation between mathematics and other fields in the American educational system. Understanding the Problem presents the potential value of exploiting these connections throughout the curriculum and the obstacles such action might encounter. Devising a Plan provides an overview of the support systems provided to early MAC initiatives by government and professional organizations. Implementing the Plan contains a brief description of early collegiate programs, their approaches and their differences. Extending the Solution details the adoption of MAC principles to the K-12 sector and throughout the world. The paper concludes with Retrospective, a brief discussion of lessons learned and possible next steps.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1845-1848
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• 2003

PD(Partial Discharge) signal have the range from several kHz to several GHz. External noises don't give any interference to discerning PD signals with high frequency bandwidth between several hundreds MHz to several GHz but, in the range between several decades kHz to several MHz, are big obstacles to prevent from discriminating PD signals. Therefore, selecting appropriate filter to decrease the influence of noise is important problem. PD signals have the characteristics both short duration and non-continuous pulse train. For separating PD signals from External noises, some different filtering methods different from conventional ones are needed and wavelet filtering method was convinced to be suitable filtering method in various investigations. This paper has simulated PD signal and various noises and investigated the influences for the performance of wavelet filter by varying the components relative to designing of wavelet filter and constructed suitable one. For the purpose of convincing the performance of wavelet filter, real PDs were produced in needle to plane electrode structure. This small PD signal was mixed with external noises and filtered with wavelet filter. We have obtained apparent PD signals and noises are well suppressed by wavelet filter.

• 한국전기전자재료학회논문지
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• 제24권10호
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• pp.775-778
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• 2011

TBP (tertiarybutylphosphine), a relatively new material for phosphorus, has been studied with EDMIn (ethyldimethylindium) as an indium source for the growth of InP by MOVPE (metalorganic vapor phase epitaxy). Mirror smooth and good crystalline InP layers were obtained at $500-600^{\circ}C$ with the TBP/EDMIn molar ratio as low as 21. The deposited InP layers are all n-type with the electron concentration in the range of (5-10)${\times}10^{16}\;cm^{-3}$, which is a lot higher than those from $PH_3$. This high concentration is due presumably to the high concentration of donor impurities in TBP. And it has been found that the formation of adduct occurs between EDMIn and TBP at room temperature when the partial pressure of EDMIn in the reactant mixture is above $1{\times}10^{-2}$ Torr. The high concentration of impurities in TBP and the adduct formation between EDMIn and TBP are major obstacles in replacing $PH_3$ and TMIn for the growth of device quality InP layers.

• 대한지리학회지
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• 제30권3호
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• pp.230-241
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• 1995

제주도에서 때때로 밭생하는 동해(凍害) 는 감귤 농사에 많은 영향을 준다. 특히 한 라산 북사면의 감귤 과수원에서는 대규모의 동해 뿐만 아니라 소규모 냉기류의 정체로 인하 여 품질과 생산성이 낮아지는 경우가 빈번하다. 본 연구는 감귤 과수원지역의 동해나 한해 (寒害)로 인한 피해 방지를 모색하기 위한 연구의 일환으로서 1989-1990년 겨울에 동해 피 해가 컸던 북제주군 와산리 일대를 사례로 택한 1995년 1월 관측 결과를 중심으로 기온 분 포의 특성을 분석하였다. 기상조건에 따라서 고지대(해발 200m 이상의 지역)와 저지대(해발 200m미만의 지역)의 최저기온 분포가 다르게 나타났다. 흐리고 바람이 강한 날과 강수현상 이 있는 날에는 고지대의 기온이 낮은데, 저지대와의 차이는 전자의 경우 2.4$^{\circ}C$, 후자의 경 우 0.2$^{\circ}C$ 정도이다. 반면 바람이 없고 맑은 날 야간에는 저지대보다 고지대의 기온이 높은데 최대 차이는 4.8$^{\circ}C$에 달하였다. 방풍 시설에 의하여 밀폐된 곳이나 지형적으로 함몰된 와지 에서는 냉기류가 정체되면서 소규모의 냉기호가 형성되었다. 그리고 최대 강도 3.1$^{\circ}C$ 에 이 르는 지표면의 복사냉각에 의한 기온 역전 현상이 발생하는데, 방풍시설로 완전히 밀폐된 고도인 90cm까지 뚜렷하게 저온현상이 나타났다. 방풍림과 방풍담으로 밀폐된 곳에서는 방 풍 시설의 전면과 후면의 기온차가 2.O$^{\circ}C$에 이르고 있다. 저지대에 냉기호가 형성되었을 경 우, 인공적으로 소규모의 대류현상을 일으켜 냉기호 내의 기온을 상승시키는대 큰효과를 얻 을 수 있었다. 본 연구의 결과는 실측에 의한 상습 냉해지역의 파악과 냉해 방지를 위한 합 리적인 방풍시설의 설계의 방요성이 시급함을 보여준다.

• The Korean Journal of Physiology and Pharmacology
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• 제16권3호
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• pp.167-174
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• 2012

Natural killer (NK) cells provide one of the initial barriers of cellular host defense against pathogens, in particular intracellular pathogens. Because bone marrow-derived hematopoietic stem cells (HSCs), lymphoid protenitors, can give rise to NK cells, NK ontogeny has been considered to be exclusively lymphoid. Here, we show that porcine c-$kit^+$ bone marrow cells (c-$kit^+$ BM cells) develop into NK cells in vitro in the presence of various cytokines [interleukin (IL)-2, IL-7, IL-15, IL-21, stem cell factor (SCF), and fms-like tyrosine kinase-3 ligand (FLT3L)]. Adding hydrocortisone (HDC) and stromal cells greatly increases the frequency of c-$kit^+$ BM cells that give rise to $CD2^+CD8^+$ NK cells. Also, intracellular levels of perforin, granzyme B, and NKG2D were determined by RT-PCR and western blotting analysis. It was found that of perforin, granzyme B, and NKG2D levels significantly were increased in cytokine-stimulated c-$kit^+$ BM cells than those of controls. And, we compared the ability of the cytotoxicity of $CD2^+CD8^+$ NK cells differentiated by cytokines from c-$kit^+$ BM cells against K562 target cells for 28 days. Cytokines-induced NK cells as effector cells were incubated with K562 cells as target in a ratio of 100 : 1 for 4 h once a week. In results, $CD2^+CD8^+$ NK cells induced by cytokines and stromal cells showed a significantly increased cytotoxicity 21 days later. Whereas, our results indicated that c-$kit^+$ BM cells not pretreated with cytokines have lower levels of cytotoxicity. Taken together, this study suggests that cytokines-induced NK cells from porcine c-$kit^+$ BM cells may be used as adoptive transfer therapy if the known obstacles to xenografting (e.g. immune and non-immune problems) were overcome in the future.

• 한국정보통신학회논문지
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• 제20권7호
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• pp.1243-1248
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• 2016

본 논문에서는 4.4GHz 대역에서 항공기내 무선 통신을 위한 채널 링크 버짓을 분석하였다. 항공기내의 채널을 일반적인 경로 손실, 장애물로 인한 음영효과, 그리고 다중 경로 신호로 인한 페이딩의 조합으로 모델링하였다. 그리고, 항공기내에 존재할 수 있는 송수신기의 다양한 위치에 따라서 채널을 A~F의 6개 그룹으로 분류하고, 6개의 채널 그룹별로 최대 전송 가능 거리와 전송 오류 확률 측면에서 링크 버짓을 분석하였다. 다양한 분석과 컴퓨터 시뮬레이션 결과에 따르면, A, B, F 채널 그룹이 C, D, E 그룹 대비 우수한 전파 특성을 가지며, 그룹 E의 전파 특성이 가장 열악한 것으로 확인되었다. 이러한 결과들은 항공기내 또는 이와 유사한 환경에서의 채널 분석을 위한 기초자료로 활용 가능하다.

• 한국통신학회논문지
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• 제39C권12호
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• pp.1267-1279
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• 2014

본 논문에서는 근거리 레이더의 특성 분석을 통한 선박 내 안전을 위한 물체탐지 시스템의 개발에 초점을 두었다. 근거리용 레이더들은 가격이 저렴한 대신에 자동차와 같은 특수 용도로 개발되었으므로 다른 곳에 적용하기 위해서는 기기의 특성 분석과 다양한 환경에서의 실험을 통한 데이터 특성 분석이 필수적이다. 또한 본 연구의 목표인 사람 및 물체의 정확하고 신속한 감지 시스템의 구성을 위해서는 입력되는 많은 반사 신호들 중에서 이동하는 물체만을 정확하게 분류하여 표시하기 위한 데이터 클러스터링 알고리즘이 필요하다. 본 연구에서는 이를 위해 반사되는 데이터들의 궤적정보와 속도 및 RCS 값을 이용한 클러스터링 알고리즘을 제안 하였다.