http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
핫 프레스 벤딩 공정에서 냉각회로 최적화를 위한 공정변수의 평가
남기주(Ki-Ju Nam),최홍석(Hong-Seok Choi),고대철(Dae-Cheol Ko),김병민(Byung-Min Kim) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.11
Hot press forming can produce high-strength components by rapidly cooling between closed punch and die after hot forming using quenchable boron steel austenized in a furnace. In the hot press forming process, the cooling rate is influenced by the size, position and arrangement of the cooling channel and the file condition of cooling water in the die. Also, mechanical properties of the final components and operation time are related to cooling rate. Therefore, the design of optimized cooling channel is one of the most important works. In this paper, the effect of position and size of the cooling channel on the cooling rate was investigated by using design of experiment and FE analysis in hot press bending process. Therefore the optimum cooling channel ratio was presented in the HPB.
AHP를 활용한 복합리조트 방문요소 중요도 분석 : 전문가 인식을 중심으로
남기주(Nam, Ki-Ju),조미정(Cho, Mi-Jeong) 한국지역개발학회 2019 韓國地域開發學會誌 Vol.31 No.5
This study analyzed the importance and priority of what part of the complex resort business influenced demand from the viewpoint of visitors. The purpose of this study was to present the policy directions of the relevant ministries and the implications for establishing the operation plan to the project developers by utilizing the importance and priority. Based on the results of this study, it is possible to use this results for ministries or municipalities in Korea who planning the integrated resort business directly or to do that for private business partners. And, it is expected to use when setting criteria for integrated resort’s location and set the kind and volume of facilities as well as casinos.
장단기 금리스프레드와 신용스프레드가 경기동행지수에 미치는 영향 분석
남기주(Ki-Ju Nam) 한국산업경제학회 2014 산업경제연구 Vol.27 No.1
수익률곡선은 향후 경기방향에 대한 시장의 기대와 예측, 통화당국의 통화정책 운영방향에 대한 정보를 반영하고 있어 미래 경기 예측에 중요한 정보변수이다. 경기상승이 예상되면 금리스프레드가 확대되고, 경기하락이 예상되면 금리스프레드는 축소된다. 본 연구는 경기선행지수 산출지표들의 경기선행성 논란이 커지고있는 가운데 2006년부터 산출지표로 사용되고있는 금리스프레드가 경기대용변수인 경기동행지수에 정확히 어느 정도 선행하는 지를 분석하였다. 그 결과 여러 장단기 금리스프레드중 국고채(3년)와 CD 금리스프레드는 전체기간(2000.1~2013.7)에서 10개월 선행하여 경기동행지수에 유의한 영향을 미쳤고, 5개월 선행시점에서 영향력이 가장 컸다. 금융위기 이전 기간에선 7개월 선행하여 유의한 영향을 미쳤다. 설명변수에 AR(2)를 추가했을 경우에는 4개월 선행하여 유의한 영향을 미쳤다. VAR모형을 이용한 충격반응함수 결과에서도 금리스프레드는 8~9개월까지 지속적으로 상승하면서 경기동행지수에 영향력을 미치는 것으로 나타났다. 따라서 우리나라의 경우 장단기 금리스프레드는 최소 1분기~3분기 경기에 선행하여 움직이는 정보변수인 것으로 판단된다. 한편 경기상승이 예상되면 신용스프레드가 축소되고, 경기하락이 예상되면 신용스프레드는 확대될 것으로 예상된다. 경기동행지수에 대해 신용스프레드의 차분변수를 회귀분석한 결과와 VAR모형을 이용한 충격반응함수 추정결과 모두에서 음(-)의 부호가 나왔다. 이는 경기가 상승할 경우 신용프레드가 축소된다는 의미로 일반적인 예상과 일치되는 결과를 보였다. This dissertation investigate whether a positive slope of the yield curve is associated with a future increase in coincident composite index as proxy measure of real business cycle and a flatting and a negative slope of the yield curve is associated with a future decrease in coincident composite index. The findings are as follows: For whole sample period, the effect of yield spread to coincident composite index lasts for 10 months and maximum effect is after 5 months. Yield spread have predictive power 1 to 3 quarter ahead to business variables(coincident composite index). Chow testing results about whether a break occurs at global financial crisis in September 2008 show that there is a break in the population regression coefficients. Credit spread(using spread between treasury bond(3 year) yield and BBB- corporate bond yield) will be reduced in business expansion, but will be increased in business recession. after regression analysis, the coefficient of regression is (-) as expected and the effect of credit spread to coincident composite index lasts for 10 months.
핫 프레스 벤딩 공정에서 냉각회로 최적화를 위한 공정변수의 평가
임우승(Woo-Seung Lim),남기주(Ki-Ju Nam),최홍석(Hong-Seok Choi),고대철(Dae-Cheol Ko),김병민(Byung-Min Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
The cooling rate in the hot stamping process is influenced by the size, position and arrangement of the cooling channel and the flow condition of cooling water. And, mechanical property of final stamped part and total process time are related to cooling rate. Therefore, the design of optimized cooling channel is most important process parameter in the hot stamping process. In this paper, design of experiment and FE-Analysis are applied to evaluate process parameters of cooling channel which has an influence on cooling rate. And J-MatPro, known as reliable material property modeler, was used to obtain the thermal and mechanical properties of boron steel. FE-Analysis was carried out for heating, thermo-mechanical coupled simulation and phase transformation simulation in hot press bending process. It can be presented that condition of the cooling channel, which has high cooling rate to improve the mechanical properties of hot formed product.
균일한 강도를 가진 핫스템핑 부품 제조를 위한 냉각 채널 최적 설계 및 V-굽힘 공정에의 적용
임우승(Woo-Seung Lim),최홍석(Hong-Seok Choi),남기주(Ki-Ju Nam),김병민(Byung-Min Kim) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.5
In recent years, hot-stamped components are more increasingly used in the automotive industry in order to reduce weight and to improve the strength of vehicles. In hot stamping, blank is hot formed and press hardened in a water-cooled tool to achieve high strength. However, temperature of the tool increases gradually, in mass production of hot stamped component thus critical cooling rate for obtaining high strength over 1500㎫ goes down. Therefore, tools should be rapidly cooled down by the coolant which flows through cooling channel. Hereby, optimal design of cooling channel to obtain uniform and high strength of the component will be presented in this paper. Application to V-bending process is explained in detail. As a result of optimal design, temperature deviation and average temperature of the blank in comparison with previous researches has reduced about 31 % and 15%, respectively.