• 자원환경지질
• /
• 제43권5호
• /
• pp.523-528
• /
• 2010

미국발 금융위기 여파로 세계경제가 침체되변서 LME의 base metal 가격이 2008년 4/4, 분기 급락하였으나, 2009년 1-7월 거시경제 회복신호와 함께 base metal 가격이 다시 상승세를 보였다. Base meta1 상승 배경에는 미국 기업들의 개선된 실적 발표로 산업생산 및 제조업지수가 개선된 것 미달러화 약세로 인한 원자재 가격 상승, 그리고 무엇보다도 세계 금융 위기 속에도 경제성장을 위한 중국의 원자재 수요 증가가 주요 원인으로 꼽힌다. 이에 본 논문에서는 base metal 가격상승에 주요 base metal소비국의 수요가 영향을 주었는지를 중국 및 주요국 경제성장률을 가지고 회귀분석 하였다. 분석결과 중국의 경제 성장만이 LME시장의 base metal 가격상승에 영향을 주는 것으로 나타났다. 하지만 이런 결과에도 불구하고, 그동안 중국 상품의 주요 소비시장이었던 미국, 유럽 동 선진국들 경제의 본격적인 회복 없이 중국경제만으로 base metal 가격 상승랠리가 지속될지 여부를 보고자 한다.

• 복식
• /
• 제58권6호
• /
• pp.35-41
• /
• 2008

The purposes of this study lied in the analysis and classification of neck-base circumference shapes of the women in their twenties, by the application of three-dimensional automatic measurement data of human body, and thereby in the understanding of neck-base circumference shapes by the classified type. The findings are as follows: 1. The comparison of three-dimensional human body measurement items relating to the neck-base circumference part of the women in their twenties indicated that the largest individual difference was found in cervicale-center-anterior neck radius than in other items. 2. The factor analysis, which was conducted to extract the factors constituting the neck-base circumference, showed the shape of cervicale(factor 1), the shape of section neck(factor 2), the thickness of neck(factor 3), the shape of anterior neck(factor 4), and the shape of side neck(factor 5). 3. The classification of the neck-base circumference shapes resulted in three types. Type 1 was the shape of a reverse triangle hanging forward, Type 2 was that of a circle, and Type 3 was that of an oval open to the sides.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제14권3호
• /
• pp.151-161
• /
• 2010

A reversed trapezoidal fin is analyzed using a two-dimensional analytical method. Heat loss from the reversed trapezoidal fin is presented as a function of the fin shape factor, fin base thickness and the fin base height. The relationship between the fin tip length and the convection characteristic number as well as that between the fin tip length and the fin base height for equal amounts of heat loss are analyzed. Also the relationship between the fin base thickness and the fin shape factor for equal amount of heat loss is presented. One of the results shows that the heat loss decreases linearly with the increase of the fin shape factor.

• 한국군사과학기술학회지
• /
• 제10권3호
• /
• pp.208-216
• /
• 2007

As the propellant mass is being accelerated out of the gun chamber along with the projectile, a continuous pressure gradient exists between the end of chamber and the base of the projectile. For this reason, the base pressure-travel curve is very important to design a conventional gun barrel in the interior ballistics, but it is not obtained briefly by empirical or theoretical method. In this paper, a simple relation between chamber pressure and base pressure was determined by the factor of base pressure(Cb) obtained from the experimental method. The simple relation gives a reasonable prediction for the reduction of pressure between the breech and the base of projectile owing to the axial gradient in the gun tube. The predictions have been validated by the infrared screen sensor and the PRODAS(PROjectile Design and Analysis System) for interior ballistic systems. Therefore, the base pressure-travel curve could be calculated from the chamber pressure measured by piezoelectric sensor. The base pressure-travel curve obtained from the simple relation offers initial information to gun barrel designer and is used for calculation of muzzle velocity.

• International Journal of Air-Conditioning and Refrigeration
• /
• 제16권3호
• /
• pp.83-88
• /
• 2008

A geometrically asymmetric trapezoidal fin is analyzed using the one-dimensional analytic method. Heat loss and thermal resistance are represented as a function of the fin base thickness, base height, fm shape factor, inside fluid convection characteristic number, convection characteristic numbers ratio, fm length and ambient convection characteristic number. The relationship between the fin base height and the shape factor for equal amounts of heat loss is presented. One of the results shows that the variations of the fm base thickness and the inside fluid convection characteristic number give no effect on the thermal resistance.

• 한국자동차공학회논문집
• /
• 제19권4호
• /
• pp.24-31
• /
• 2011

Performance of the asymmetric trapezoidal fin with various upper lateral surface slopes is investigated by using the two-dimensional analytic method. For a fin base boundary condition, convection from the inner fluid to the inner wall, conduction from the inner wall to the fin base and conduction through the fin base are considered. Heat loss and fin efficiency are represented as a function of the fin base thickness, base height, inner fluid convection characteristic number, fin tip length and fin shape factor. One of the results shows that heat loss increases while fin efficiency decreases as the fin shape factor increases.

• 설비공학논문집
• /
• 제20권7호
• /
• pp.455-461
• /
• 2008

A reversed trapezoidal fin with variable fin base thickness is optimized using a two-dimensional analytical method. For the fin base boundary condition, instead of a constant temperature, heat transfer from the inside fluid to the fin base is considered. Heat loss from the fin tip is not ignored. The maximum heat loss, corresponding optimum fin effectiveness, fin length and base height are presented as a function of the fin base thickness, shape factor and volume.

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

• Earthquakes and Structures
• /
• 제5권1호
• /
• pp.23-48
• /
• 2013

In this study, the effect of flexibility of superstructures and nonlinear characteristics of LRB (Lead Rubber Bearing) isolator on inelastic response of base isolated structures is investigated. To demonstrate the intensity of damage in superstructures, demand response modification factor without the consideration of damping reduction factor, demand RI, is used and the N2 method is applied to compute this factor. To evaluate the influence of superstructure flexibility on inelastic response of base isolated structures, different steel intermediate moment resisting frames with different heights have been investigated. In lead rubber bearing, the rubber provides flexibility and the lead is the source of damping; variations of aforementioned characteristics are also investigated on inelastic response of superstructures. It is observed that an increase in height of superstructure leads to higher value of demand RI till 4-story frame but afterward this factor remains constant; in other words, an increase in height until 4-story frame causes more damage in the superstructure but after that superstructure's damage is equal to the 4-story frame's. The results demonstrate that the low value of second stiffness (rubber stiffness in LRBs) tends to show a significant decrease in demand RI. Increase in value of characteristic strength (yield strength of the lead in LRBs) leads to decrease in the demand RI.

• Earthquakes and Structures
• /
• 제8권5호
• /
• pp.1091-1111
• /
• 2015

Base isolation is an effective method for protecting structures against earthquake hazard. It elongates the period of vibration and introduces supplemental damping to the structural system. The stiffness, damping and displacement are coupled forcing the code seismic design procedure to be unnecessarily complicated. In addition, the force reduction factor -a key parameter in the design procedurehas not been well addressed by seismic design codes at the high levels of damping due to the pronounced difference between pseudo and actual accelerations. In this study, a comparison has been conducted to evaluate eight different methods, in the literature, for calculating the force reduction factor due to damping. Accordingly, a simplified seismic analysis procedure has been proposed based on the well documented N2 method. Comprehensive analysis has been performed for base-isolated structure models for direct application and verification of the proposed procedure. The results have been compared with those of the European code EC8, the nonlinear time history analysis and investigations in the literature, where good agreement has been reported. In addition, a discussion has been elaborated for the resulted response of the base-isolated structure models with respect to the dynamic characteristics of the base isolation system.