• Spatial Information Research
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• 제21권1호
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• pp.37-44
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• 2013

본 연구에서는 U-City 전문가들에 대한 설문조사를 통해 U-City산업을 선정하고 이를 바탕으로 산업연관분석을 수행하였다. 그 결과로 U-City산업의 생산유발계수, 부가가치유발계수, 고용 및 취업유발계수, 영향력계수, 감응력 계수를 도출하였다. 이러한 계수들을 통해 U-City 산업의 전반적 특성과 파급효과를 확인하였다. U-City 산업은 전 산업 평균에 비해 부가가치유발효과, 고용유발효과가 큰 것으로 나타났으며 전방연쇄효과가 큰 산업이라는 특징을 확인하였다. 본 연구는 U-City산업에 대한 합리적 정의와 다양한 파급효과를 도출하여 정책 판단의 기초자료로 활용될 수 있다는 점에서 의미가 있다.

• Steel and Composite Structures
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• 제16권4호
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• pp.375-387
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• 2014

The purpose of this paper is to propose a method for evaluation of varying stiffness coefficients of tailored conical shells (TCS). Furthermore, a comparison between buckling loads of these shells under axial load with the different fiber path is performed. A circular truncated conical shell subjected to axial compression is taken into account. Three different theoretical path containing geodesic path, constant curvature path and constant angle path has been considered to describe the angle variation along the cone length, along cone generator of a conical shell are offered. In the TCS with the arbitrary fiber path, the thickness and the ply orientation are assumed to be functions of the shell coordinates and influencing stiffness coefficients of the structure. The stiffness coefficients and the buckling loads of shells are calculated basing on classical shells theory (CST) and using finite-element analysis (FEA) software. The obtained results for TCS with arbitrary fiber path, thickness and ply orientation are derived as functions of shell longitudinal coordinate and influencing stiffness coefficients of structures. Furthermore, the buckling loads based on fiber path and ply orientation at the start of tailored fiber get to be different. The extent of difference for tailored fiber with start angle lower than 20 degrees is not significant. The results in this paper show that using tailored fiber placement could be applied for producing conical shells in order to have greater buckling strengths and lower weight. This work demonstrates the use of fiber path definitions for calculated stiffness coefficients and buckling loads of conical shells.

• Geomechanics and Engineering
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• 제10권1호
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• pp.21-35
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• 2016

Employing non-associated flow rule and Power-Law failure criterion, the failure mechanisms of tunnel roof in homogeneous and layered soils are studied in present analysis. From the viewpoint of energy, limit analysis upper bound theorem and variation principle are introduced to study the influence of dilatancy on the collapse mechanism of rectangular tunnel considering effects of supporting force and seepage force. Through calculation, the collapsing curve expressions of rectangular tunnel which are excavated in homogeneous soil and layered soils respectively are derived. The accuracy of this work is verified by comparing with the existing research results. The collapsing surface shapes with different dilatancy coefficients are draw out and the influence of dilatancy coefficient on possible collapsing range is analyzed. The results show that, in homogeneous soil, the potential collapsing range decreases with the decrease of the dilatancy coefficient. In layered soils, the total height and the width on the layered position of possible collapsing block increase and the width of the falling block on tunnel roof decrease when only the upper soil's dilatancy coefficient decrease. When only the lower soil's dilatancy coefficient decrease or both layers' dilatancy coefficients decrease, the range of the potential collapsing block reduces.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.147-150
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• 2004

수자원을 평가하기 위해서는 먼저 한 지점에서 측정된 강수량을 보간해야 할 필요가 있다. 이를 위하여 강수현상에 영향을 주는 지형변수를 TOVA(Topographic Variables Extraction Program)를 이용하여 고도(ELEV), 경사(SLOPE), 바다까지의 거리(SEA), 방해물(OBST), 방벽(BAR), 굴곡도(SHIELD)로 구분하고 2000.1.1부터 2002.12.31까지의 강수량 자료를 사상별로 추출하여 이들을 서로 비교 분석하였다. 결정계수로 보면 각기 강수사상마다 지형의 영향이 다르게 나타나며 ELEV와 남서방향의 SLOPE, OBST 그리고 전 방향의 SHIELD가 강수량과 관계가 깊은 것으로 나타났다. 다중회귀분석 모형은 강수량의 공간적 변동량의 96%를 설명한다.

• 대한치과교정학회지
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• 제16권2호
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• pp.69-80
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• 1986

This study was undertaken to investigate the inheritance in craniofacial complex among Korean familial members. The subjects were 160 lateral cephalometric radiographs from 45 families. Standard product-moment correlation coefficients(r) were calculated for the measurements between the familial pairings. Further, coefficients of $determination(r^2)$ were calculated and multiple regression analyses were performed to assess the use of parents' record for predicting an offspring's craniofacial features. The following results were obtained. 1. First-degree relatives had a high level of significant correlations which were compatible with a polygenic theory of inheritance than those of non-relatives. 2. Mother-daughter pair had the highest significant correlations, then mother-son and father-son pairs, and, finally, father-daughter pair had the lowest significant correlations. 3. The genetic influence was higher in anterior cranial base length and genial angle. In contrast, the environmental influence was higher in posterior border of ramus, maxillary ant. teeth, maxillary & mandibular apical bases and Gla-P. occ. 4. The predictability of offspring's cranio-facial growth could be improved by using multiple measurements from both parents than those from father or mother only.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.164-180
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• 2003

A series of cooperative interlaboratory tests (round robins) was conducted in 1997, 1998, 1999, 2000, 2001, 2002 and 2003 by the DIN 51834 Working Group on Tribological Tests in Translatory Oscillation Apparatus. The statistical analysis of these test results shows the influence of cleaning solvent, machine model and evaluation criteria on the tribological properties of the lubricants tested. Coefficients of friction and wear results are ranked according to the effects of ten different cleaning solvents, where isopropanol gave the lowest values and isoparaffin solvents the highest. The effect of machine model on coefficients of friction varied from about $0.2\%\;to\;0.9\%$ of the mean. Wear results were not affected. The tests also showed that the seizure criteria and methods of measuring wear required for in the test procedure do not provide a suitable measure of the tribological properties of some lubricants. The precision was Improved by introducing a grease apply caliper as well as an increased stroke to 1,5 mm and running-in. The temperature does not affect the precision of the oil test procedure.

• 대한기계학회논문집B
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• 제23권7호
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• pp.864-870
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• 1999

An experimental study Is conducted in a four-vane linear cascade in order to examine the influence of the wake behind rectangular bars on the flow and heat transfer characteristics. Flow and heat transfer measurements are made for the inlet Reynolds number of 66000(based on chord length and free-stream velocity). Turbulent intensity and stress are measured using a hot-wire anemometer, and to measure the convective heat transfer coefficients on the blade surface liquid crystal/gold film Intrex technique is used. Each of experimental cases is characterized by the unsteadiness measured at the entrance of the cascade. The wake behind the rectangular bars enhances the turbulent motion of the flow in the cascade passage. It also promotes the boundary layer development and transition. The results show that heat transfer coefficients on the blade surface increase with increasing unsteadiness.

• Advances in aircraft and spacecraft science
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• 제8권1호
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• pp.53-67
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• 2021

The increasing interest in the exploration of Mars stimulated the authors to study aerodynamic problems linked to space vehicles. The aim of this paper is to evaluate the aerodynamic effects of a flapped wing in collaborating with parachutes and retro-rockets to reduce velocity and with thrusters to control the spacecraft attitude. 3-D computations on a preliminary configuration of a blunt-cylinder, provided with flapped fins, quantified the beneficial influence of the fins. The present paper is focused on Aerodynamics of a wing section (NACA-0010) provided with a trailing edge flap. The influence of the flap deflection was evaluated by the increments of aerodynamic force and leading edge pitching moment coefficients with respect to the coefficients in clean configuration. The study was carried out by means of two Direct Simulation Monte Carlo (DSMC) codes (DS2V/3V solving 2-D/3-D flow fields, respectively). A DSMC code is indispensable to simulate complex flow fields on a wing generated by Shock Wave-Shock Wave Interaction (SWSWI) due to the flap deflection. The flap angle has to be a compromise between the aerodynamic effectiveness and the increases of aerodynamic load and heat flux on the wing section lower surface.

• 한국콘텐츠학회논문지
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• 제11권12호
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• pp.884-892
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• 2011

관광산업의 산업연관분석은 최근의 서비스산업에 대한 정책적 관심이 증가하고 있는 상황에서 경제적 효과를 측정하는 수단으로 유용성이 높다. 2007년과 2008년 산업연관표를 통하여 생산유발계수, 부가가치 유발계수, 수입유발계수, 영향력계수와 감응도계수를 도출하였다. 분석결과, 산업연관분석의 주요지표들은 최승이[6]의 연구와 비교하여 커다란 차이가 나타나지 않았다. 본 연구에서 관광산업의 범위를 축소한 상황에서도 비슷한 결과를 보인 것은 과거에 비해 관광산업의 영향력이 커진 것으로 추측된다. 향후 연구에서는 관광산업의 분류에 대한 합의가 필요하며, 각종 계수를 전체적으로 도출하는 것 뿐만 아니라 세부적인 관광산업에 대해서도 분석이 진행되어야 한다.

• International Journal of Precision Engineering and Manufacturing
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• 제6권1호
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• pp.51-58
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• 2005

The development of the high-efficiency machine-tools equipment and new cutting tool materials with high hardness, heat- and wear-resistance has opened the way to application of high-speed cutting process. The basic argument of using of high-speed cutting processes is the reduction of time and the respective increase of machining productivity. In this sense, the spindle units may be regarded as one of the most important units, directly affecting many parameters of high-speed machining efficiency. One of the possible types of spindle units for high-speed cutting is the air-bearing type. In this paper, we propose the mathematical model of the dynamic behavior of the air-bearing spindle. To provide the high-level of speed capacity and spindle rotation accuracy we need the adequate model of "spindle-bearings" system. This model should consider characteristics of the interactions between system components and environment. To find the working characteristics of spindle unit we should derive the equations of spindle axis movement under the affecting factors, and solve these equations together with equations which describe the behavior of lubricant layer in bearing (bearing stiffness equations). In this paper, the three influence coefficients are introduced, which describe the center of spindle mass displacement, angle of shaft rotation around the axes under the unit force application and that under the unit torque application. These coefficients are operated in the system of differential equations, which describes the spindle axis spatial movement. This system is solved by Runge-Kutta method. Obtained trajectories and amplitude-frequency characteristics were then compared to experimental ones. The analysis shows good agreement between theoretical and experimental results, which confirms that the proposed model of air-bearing spindle is correctis correct