요트 설계시 선형의 기하학적 특성과 성능 사이의 관련성에 관한 연구

하득기(DEUCK-GI HA),김수영(SOO-YOUNG KIM),김용재(YONG-JAE KIM) 한국해양공학회 2003 韓國海洋工學會誌 Vol.17 No.6

Yacht design is significantly affected by the hull geometrical characteristics. Therefore, it is necessary to closely examine the relation between hull and performance, before considering characteristics of sea condition. In this study, Genetic Programming is used to derive a formula for the relationship between hull geometric characteristics and performance. Using the formula, a new guideline is proposed to determine performance of a yacht.

기하학적 도형의 형태적 특징이 크기지각에 미치는 영향

김현정(Kim, Hyeon-Jeong) 인제대학교 디자인연구소 2008 Journal of Integrated Design Research (JIDR) Vol.7 No.2

본 연구는 평면 기하학적 도형의 형태적 특징이 크기지각에 미치는 영향에 대해 검토한 것으로, 삼각형, 역삼각형, 정사각형, 원, 마름모, 가로/세로 직사각형, 오각형, 육각형의 각기 다른 9개의 기하학적 패턴 도형에 대한 크기지각이 검토되었다. 실험에 사용된 각 패턴들의 면적은 모두 동일하며, 실험참가자는 선과 면으로 나타내어진 기하학적 패턴들의 지각적 크기를 순위법에 의해 평가한다. 연구결과 삼각형과 역삼각형의 형태가 가장 크게 지각되는 것으로 밝혀졌으며, 세 번째로 마름모의 형태가 크게 지각되는 것으로 밝혀졌다. 그리고 연구고찰 결과 도형의 선길이(혹은 둘레), 내각(예각/둔각), 배치방향 등의 기하학적 요소가 크기지각에 직접적인 영향을 미치고 있는 것으로 고찰 검토되었다. The present study was designed to investigate how size perception of plane geometrical patterns was influenced by configurational characteristics. Nine planes with different configurations (triangle, inverted triangle, square, circle, diamond, horizontal and vertical rectangles, pentagon, and hexagon) were used as test patterns. The physical area of each test pattern was the same and was depicted by line and painting. Subjects were asked to rank the test patterns in order of perceived size. It was found that the triangle and inverted triangle shapes were perceived as the largest; with the diamond third. These results imply that the periphery, interior angle, and orientation of the plane were the main determinants of size perception.

A Study on the Air-Lubricated Herringbone Groove Journal Bearing by Finite Element Method

Park, Shin Wook,Rhim, Yoon Chul Korean Tribology Society 2001 KSTLE International Journal Vol.2 No.1

The herringbone groove journal bearing (HGJB) has chevron type grooves on stationary or rotating member of the bearing so that they pump the lubricant inward the grooves when journal rotates. As a result, the pressure is generated around the journal so that the radial stiffness and dynamic stability are improved comparing to the plain journal bearing (PJB) when the bearing operates near the concentric condition. The narrow groove theory, conventionally adopted to simulate the concentric operation of HGJB, is limited to the infinite number of grooves. A numerical study of air-lubricated HGJB is presented for the finite number of grooves. The compressible isothermal Reynolds equation is solved by using Finite Element Method together with the Newton-Raphson iterative procedure and perturbation method. The solutions render the static and dynamic performances of HGJB. Comparison of present results with a PJB validates previously published finite difference solution. The HGJB's geometric parameters influence its static and dynamic characteristics. The optimum geometric parameters are presented for the air-lubricated HGJB in particular conditions.

진동제어 콘크리트 개발에 관한 실험적 연구(I)

정영수,이대형,최우성 한국콘크리트학회 1996 콘크리트학회지 Vol.8 No.5

최근의 각종 사회시설의 확충에 따른 건설공사 및 교통시설 등은 많은 진동을 유발하여 사회적인 문제를 야기하고 있는 실정이다. 본 연구는 각종 제진재료를 이용하여 진동을 억제할 수 있는 콘크리트를 개발하여 각종 건설공사에서 흔히 발생할 수 있는 진동공해문제를 억제하고자 하며 아울러 폐기물의 재활용차원에서 폐자재를 이용하여 유용한 제진콘크리트를 개발하고자 하는데 그 목적이 있다. 우선, 제진재료를 이용한 압축강도 200kg/$\textrm{cm}^2$ 이상의 콘크리트 배합비를 찾기 위하여 Pilot실험을 수행하였으며, 선정된 적정배합비에 다른 진동시험제를 제작하여 재료의 동적특성 즉, 1차공명진동수, 동탄성계수 및 감쇠비를 측정하여 제진효과를 조사하였다. 제진재료로서는 Foam, Latex, Rubber Powder 그리고 Plastic Resin 등을 사용하였으며 진동의 감쇠효과가 있는 것으로 나타났다. 실험방법으로는 KS F 2437 규정과 진동파의 속도법을 사용하였으며, 감쇠비 측정은 Frequency Response Spectrum 곡선에 대한 Polynomial Curvefitting방법과 기하학적 해석방법을 이용하여 각각의 결과를 비교.분석하였다. Recently, the construction of infrastructures has been booming and accelerating to keep up with rapid economic growth. Construction activities and operation of transportation facilities cause unfavorable effects such as civil petitions associated with vibration-induced damages or nuisances. Accordingly, the objective of this study is to develop vibration-controlled concrete using various vibration-controlled mixtures, and also to recycle obsolete materials in part. As the first step to achieve this research, preliminary mix designs have been carried out to obtain an appropriate mix proportion above 200kg/$\textrm{cm}^2$ in uniaxial compressive strength. Test specimen based on the mix proportion selected have been actuated by the impact hammer to investigate their dynamic characteristics. Vibration-controlled mixtures are foam, latex, rubber powder and plastic resin, which have been determined to reduce a vibration by and large. KS F2437 and travel time method have been used to figure out 1st natural frequency and dynamic elastic moduli. Damping ratios have been computed by adopting the polynomial curvefitting method and the geometric analysis method on the frequency response spectrum curve. of which results have been compared and analyzed hereon.

○○○설계 프로젝트에서 나타나는 건축장과 프랙탈 구조의 특성에 관한 연구

이승용 한국문화공간건축학회 2018 한국문화공간건축학회논문집 Vol.- No.64

The architectural field understood the conceptual geometry of relation, but it is difficult to show the architecture as a form. To design the architectural form on the conceptual idea of the architectural field, the clue of design for form of architectural field could be found from the fractal system which is showed of the geometrical characteristic of the chaos phenomenon of nature. The fractal system has three characteristics, those are self-similarity, self-production and self-organization. The self-similarity is that the part has a similarity system as a whole, and it show the similar composition of the area of the architectural field by composing the similar network of any area among the environments, exterior and architecture. The self-production is that the making organization by combining, and it show the similar composition of the interaction of the architectural field that the architecture interact to environment and by this interaction to create new but interacted architecture continously. The self-organization is the organizing by itself on internal logic, and it show the composition of the integration of the architectural field by connecting building and space to one as a building and a space are no longer divided by flexibility, diversity and graduations. Therefore the architectural field is showed the geometrical characteristics of the fractal system.

Parametric Surface Defined on Parallelogrammic Domain and its Properties

FAN Shuqian,ZOU Jinsong,SHI Mingquan (사)한국CDE학회 2013 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8

As essential components of many mechanical systems, tooth geometrical properties of spiral bevel gears greatly influence on the kinematic and dynamic behaviors of mechanical systems. Logarithmic spiral bevel gears show unique advantage in transmission due to their constant spiral angle property. However, mathematical model suitable for accurate digital modeling, differential geometrical characteristics and related contact analysis methods of tooth surface have not been deeply investigated, since such gears are not convenient to traditional cutting manufacture in gear industry. An accurate mathematical modeling of the tooth surface geometry for logarithmic spiral bevel gears is developed, based on the basic gearing kinematics and spherical involute geometry along with the tangent planes geometry. Actually, the tooth surface is a parametric surface defined on parallelogrammic domain. Then, an equivalence proof of the tooth surface geometry is given in order to greatly simplify the mathematical model. As major factors affecting lubrication, surface fatigue, contact stress, wear and manufacturability of gear teeth, differential geometrical characteristics of the tooth surface is summarized employing classical fundamental forms. By using mentioned geometrical properties, manufacturability and its limitation of logarithmic spiral bevel gears is analyzed using precision forging and multi-axis freeform milling, instead of classical cradle-type machine tools based milling or hobbing. Geometry and manufacturability analysis result shows that logarithmic spiral gears have many application advantages, but many urgent issues such as contact tooth analysis for precision plastic forming and multi-axis freeform milling should be further solved.

마들렌느 비오네의 작품에 나타난 기하학적 특성에 관한 연구

유수경,김의경 服飾文化學會 2002 服飾文化硏究 Vol.10 No.6

The aim of this research is to analyze Vionnet's geometric features, which can be regarded as the key formative beauty among the external characteristics of her works, and to thereby establish the theory that her works emitted a time-transcending life force because they were patterns designed based on a geometrical frame of mind. To prove such argument, atudies to understand the basic geometrical aspects appearing in her works will be made by taking a look at the general features of geometry, viewing Vionnet's philosophy for designing and examining the geometric cutting methods. The period covered in this paper will center mainly on dresses Vionnet made from her very active days in the fashion sector. 1919, till when she retired from the fashopn industry, around 1939. What's outstanding about Vionnet's geometric principle expressed in her works is the unique cutting method that acknowledges the silhouette of the human body as a cubic or three-dimensions concept, through insight of the human body, the mechanics of the materials, and geometry. Vionnet introduced a simple and elegant design by combining geometric figure cuts, such as rectangles, quadrants, and triangles Moreover, she created a new sewing structure that plans everything about the materials to the tiniest detail, resulting in producing a softer style. With this, Vionnet showed the geometrical correlation can bring about harmony and the beauty of ideal proportion forming the source of eternal beauty. As discussed so far the geometrical characteristics appearing in Vionnet;s works are marked such as spirals, zig-zag lines, asymmetries, panels, gradation. golden proportion, and the mobius-band.

Optimization of geometrically asymmetric straight trapezoidal fins

강형석 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.12

Geometrically asymmetric trapezoidal fins with variable slope of fin’s top surface are optimized for fixed fin volumes. Convectionfrom the inside fluid to the inside wall, conduction from the inside wall to the fin base and conduction through the fin base are consideredsimultaneously for the fin base boundary condition. For fixed fin volumes, the optimum heat loss, the corresponding optimum fin length,and fin base height are presented as functions of the fin base thickness, inside fluid convection characteristic number, fin volume, finshape factor, and ambient convection characteristic number. The optimum values between 1-D and 2-D analyses are compared. One ofthe results shows that both the optimum fin length and fin base height decrease with the increase of the fin shape factor.

지질조건에 따른 자연사면 산사태의 기하학적 특성

김경수 ( Kyeong Su Kim ),송영석 ( Young Suk Song ),채병곤 ( Byung Gon Chae ),조용찬 ( Yong Chan Cho ),이춘오 ( Choon Oh Lee ) 대한지질공학회 2007 지질공학 Vol.17 No.1

자연사면에서의 산사태를 평가함에 있어 발생양상과 기하특성을 파악하는 것은 매우 중요하다. 이 연구는 지질을 달리하는 3개지역(장흥, 편마암류; 상주, 화강암류; 포항, 제3기퇴적암류)에서 발생한 산사태를 대상으로 지질조건에 따른 산사태의 기하양상을 분석하였다. 3개지역에서는 1998년 여름에 150~588 mm의 집중호우로 인해 총 1,582개의 산사태가 발생하였다. 이들 산사태를 조사하여 지질조건별 기하특성을 분석하였다. 산사태는 90% 이상의 사면고도에서 발생빈도가 가장 높고 70% 미만의 고도에서는 매우 낮다. 사면경사는 26~30o 범위에서 가장 많이 발생하였고 20o 미만에서는 발생빈도가 매우 낮으며 이러한 양상은 지질별로 거의 유사한 경향성을 보였다. 규모는 부피로 보아 수십부터 수백를 넘는 경우도 있으며, 그 길이는 5~300 m, 폭은 3~50 m로서 좁고 긴 형태이고 깊이는 대부분 1 m 이내로서 매우 얕은 특징을 보였다. 그리고 유형은 기반암의 표면을 파괴면으로 하여 그 상부에 위치한 토층이 미끄러지는 전이형슬라이드가주를 이루며, 토석류로 이뤄진 사태물질이 하부사면과 계곡부로 이동되면서 유동성산사태로 변화되는 양상을 보였다. The recognitions of geometrical characteristics and occurrence conditions are very important to evaluate the landslides in natural terrains. In this paper, the geometrical characteristics of landslides are analyzed according to a geological condition in three landslides areas. The three landslides areas are classified to the geological condition. The three landslides areas are Jangheung, Sangju and Pohang. The geology of Jangheung area, Sangju area and Pohang area is gneiss, granite, and the tertiary sedimentary rock, respectively. During a heavy rainfall of 150~588 mm in these areas, 1,582 landslides have occurred in 1998. The geometrical characteristics according to the geological condition analyzed from the investigation of these landslides. The frequency of landslide is high exceedingly above 90% of a slope attitude, while the frequency is very low below 70%. The frequency of landslide is high exceedingly between 26o and 30o of slope angle, while the frequency is very low below 20o. The size of the landslides is ranged from several tens to several hundreds . The length is ranged from 5 m to 300 m, and the width is ranged from 3 m to 50 m. Also, the depth is less than 1m. Therefore, the landslides in these areas have small width, long length and shallow depth. The type of the landslides is changed from transitional slide at the scarp to debris flow at the low part of slope.

Nonparametric maximum likelihood estimation of a concave receiver operating characteristic curve via geometric programming

이경은,임요한 대한수학회 2011 대한수학회보 Vol.48 No.3

A receiver operating characteristic (ROC) curve plots the true positive rate of a classifier against its false positive rate, both of which are accuracy measures of the classifier. The ROC curve has several interesting geometrical properties, including concavity which is a necessary condition for a classifier to be optimal. In this paper, we study the nonparametric maximum likelihood estimator (NPMLE) of a concave ROC curve and its modification to reduce bias. We characterize the NPMLE as a solution to a geometric programming,a special type of a mathematical optimization problem. We find that the NPMLE is close to the convex hull of the empirical ROC curve and,thus, has smaller variance but positive bias at a given false positive rate. To reduce the bias, we propose a modification of the NPMLE which minimizes the L_1 distance from the empirical ROC curve. We numerically compare the finite sample performance of three estimators, the empirical ROC curve, the NMPLE, and the modified NPMLE. Finally, we apply the estimators to estimating the optimal ROC curve of the variance-threshold classifier to segment a low depth of field image and to finding a diagnostic tool with multiple tests for detection of hemophilia A carrier.