• 한국터널지하공간학회 논문집
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• 제10권2호
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• pp.193-205
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• 2008

현재 국내에서는 유류 지하 비축 공동, 식품 저장 공동 등과 같은 지하구조물의 건설이 증가하고 있다. 이러한 지하공동의 안정성은 형상 및 크기에 영향을 많이 받는다. 따라서 본 연구는 지하공동의 형상이 안정성에 미치는 영향을 안전율을 중심으로 비교 분석하였다. 이를 위해 5가지의 공동 형상비를 가정하고 암반등급, 토피고 및 측압계수를 달리하여 민감도분석을 실시하였다. 공동의 지보재는 각각의 공동 형상, 크기 및 암반등급을 고려하여 적절한 양의 록볼트와 숏크리트로 보강하였다. 공동의 안정성은 강도감소기법을 이용하여 수치해석에 의해 얻은 안전율을 사용하여 평가되었다. 본 논문은 향후 지하공동 설계 및 안정성 평가에 도움이 될 수 있을 것으로 기대된다.

• 한국자동차공학회논문집
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• 제2권5호
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• pp.48-57
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• 1994

The specific power output and thermal effeciency of any two-stroke engine are dependent on its scavenging behavior. Among the many factors which influence on the scavenging process, the cylinder head shape is one of the important factor. Hence in this study three different type models of cylinder head shape which are the cylindrical, the spherical and the arbitrary shape are studied to show the effects of the turbulent scavenging process in the cylinder with one inlet port, two side ports and one exhaust port. A modified version of KIVA-II which strip out of or add planes of cells across the mesh above the piston for flow simulation of two-stroke engine is used. The $k-{\varepsilon}$ turbulent model is used. The results show that the flow in a two-stroke engine cylinder of the spherical head shape among the three different type model is a desirable for efficient scavenging.

• 한국의류학회지
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• 제34권7호
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• pp.1111-1125
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• 2010

Study is a basic analysis of a future virtual clothing system based on a comparative analysis of all the shirring, using a 3-dimensional apparel cad system. Frilled skirts shirred at the lower hemline were the subject of this study for a comparison of expression and shape of shirring. It compared the silhouette and details expressed in virtual and real skirts made of woolen fabrics and polyester satin, with different widths (1.5, 2 and 2.5 widths). It was found that the virtual skirt could not express shirring as exquisitely as the real skirt due to fabric thickness and other fabric characteristics. In addition, the increase in widths caused the frill shape to deform badly. In the case of a virtual skirt made of polyester satin, the increased multiplication factor let the frill spread out sharply (unlike the real skirt). Simulated skirts of polyester satin and woolen spread out to the sides with the sidelines of their frills hanging down markedly (unlike the real cloths) when the frills changed from 1.5 widths to 2 widths. When it came to the virtual skirt, side-line from the hip down all the way short of frill contorted with the wrinkle multiplication factor of 2 and 2.5 widths. This phenomenon was more notable in polyester satin skirts than in woolen skirts.

• Animal Systematics, Evolution and Diversity
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• 제24권2호
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• pp.191-197
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• 2008

Specimens of Diophrys appendiculata (Ehrenberg, ] 838) and D. scutum (Dujardin, 1841) have been collected from the coastal and brackish waters around near Ulsan, during 2004-2007. Diophrys appendiculata and D. scutum are described taxonomically for the first time in Korea. Diagnostic characteristics of these species are as follows. Diophrys appendiculata: size in vivo $43-68{\times}25-50{\mu}m$, adoral zone of membranelles (AZM) covering 43-74% of cell length in impregnated and 46-65% in vivo specimens with 32-47 adoral membranelles (AM). Paroral membrane is slightly curved. Four to five dorsal kinetal (DK) rows are fragmented and anterior and posterior parts of rows densely ciliated. Two macronuclear nodules (Ma) irregular and elongated oval in shape and widely separated. D. scutum: size in vivo $125-225{\times}75-140{\mu}m$, AZM extending to the middle of right border of body and covering 50-60% of cell length with 56-75 AMs. Body shape is typically ovoid with prominent concave margin at right posterio-lateral end, and rather thick and wide longitudinal ridge along lower buccal cavity on ventral side. Two macronuclei shaped like a sausage. five to six dorsal kineties.

• Journal of Welding and Joining
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• 제35권2호
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• pp.52-57
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• 2017

In this study, resistance spot weldability of lightweight steel with high Al contents was evaluated using various electrode shapes. The six types of electrode shape were prepared with different electrode face diameter and radius. The tensile shear tests were carried out to investigate the failure behaviors. Also, the nugget size and hardness were measured and compared with various electrode shapes. The experimental results show that the acceptable weld current region for low density lightweight steel could be obtained with 10mm electrode face diameter and 76mm electrode face radius.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권6호
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• pp.730-740
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• 2018

Hydrofoil is the direct component to generate thrust for underwater glider. It is significant to improve propulsion efficiency of hydrofoil. This study optimizes the shape of a hydrofoil using Free-Form Deformation (FFD) parametric approach and Surrogate-based Optimization (SBO) algorithm. FFD approach performs a volume outside the hydrofoil and the position changes of control points in the volume parameterize hydrofoil's geometric shape. SBO with adaptive parallel sampling method is regarded as a promising approach for CFD-based optimization. Combination of existing sampling methods is being widely used recently. This paper chooses several well-known methods for combination. Investigations are implemented to figure out how many and which methods should be included and the best combination strategy is provided. As the hydrofoil can be stretched from airfoil, the optimizations are carried out on a 2D airfoil and a 3D hydrofoil, respectively. The lift-drag ratios are compared among optimized and original hydrofoils. Results show that both lift-drag-ratios of optimized hydrofoils improve more than 90%. Besides, this paper preliminarily explores the optimization of hydrofoil with root-tip-ratio. Results show that optimizing 3D hydrofoil directly achieves slightly better results than 2D airfoil.

• 한국산업정보학회논문지
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• 제26권1호
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• pp.41-54
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• 2021

기존의 제조업 기반의 현장에서 적용되고 있는 로봇 및 이송시스템의 선형 전동기 활용에 있어서, 케이블을 통한 전력공급으로 인해 작업 환경 개선 및 기술적 고도화에 어려움을 겪고 있다. 따라서, 본 논문에서는 이러한 문제점의 해결을 위해 적용될 수 있는 비접촉 전력전송 시스템에 대해서 FEM 기반의 물리해석 프로그램을 활용하여, 2D와 3D의 자계 해석을 바탕으로 비접촉 전력전송 시스템용 고주파 코일 형상 및 전력변환 시스템에 관한 특성을 연구하였다.

• Restorative Dentistry and Endodontics
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• 제27권4호
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• pp.421-431
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• 2002

C-shaped canal configuration is very difficult to treat because that clues about preoperative canal anatomy cannot be ascertained from clinical crown morphology and limited information can be derived from radiographic examination. This study was done to get more informations about the root and canal configuration of C-shape root by 3-dimensionally reconstructing for the purpose of enhancing success rate of endodontic treatment. 30 mandibular molars with C-shaped root were selected. Six photo images from occlusal, apical, mesial, distal, buccal, lingual directions and radiographic view were taken as preoperative ones to compare them with 3-D image. After crown reduction to the level of 1-2mm over pulpal floor was performed, teeth were stored in 5.25% sodium hypochlorite solution for the removal of pulp tissue and debris. They were cleaned under running water, allowed to bench dry and embedded in a self-curing resin. This resin block was serially ground with a microtome (Accutom-50, Struers, Denmark) and the image of each level was recorded by digital camera (FinePix S1-pro, Fuji Co., Japan). The thickness of each section was 0.25mm. Photographs of serial sections through all root canal were digitized using Adobe Photoshop 5.0 and then minimum thickness of open and closed sites were measured (open site is the surface containing occluso-apical groove closed site is oppsite). After dizitization using 3-D Doctor (Able software Corp, USA). 3D reconstruction of the outer surface of tooth and the inner surface of pulp space was made. Canal classsification of C-shaped roots was performed from this 3-D reconstructed image. The results were as follows : 1. Most C-shape rooted teeth showed lingual groove (28/30). 2 According to Vertuccis' calssification, type I, II, III, IV, VII were observed. but also new canal types suck as 2-3-2, 1-2-3-2. 2-3-2-1, 2-3-2-3 were shown. 3 There was little difference in minimum thickness on coronal and apical portions, but open site were thinner than closed site on mid portion. Conclusively, 3D reconstruction method could make the exact configurations of C-shape root possible to be visualized and analyzed from multi-directions. Data from minimum thickness recommend cleaning and shaping be more carefully done on dangerous mid portion.

• Elastomers and Composites
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• 제47권4호
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• pp.347-354
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• 2012

사출성형에 CAE (Computer Aided Engineering)을 적용함으로써 사출 성형품 설계와 공정조절에 큰 도움이 된다. 또한 성형의 효율성을 최대화하고 개발기간의 단축, 그리고 고품질 제품을 확보하는데 도움이 크다. 특히 신제품 개발에 대한 설계방안을 제시하고 실패율을 감소시킬 수 있다. 현재 사출성형의 CAE는 2D는 물론 3D도 해석이 가능한데 이 두 가지 방식은 약간의 차이를 가짐에도 불구하고 해석 상 차이에 관한 비교 및 일반적인 가이드라인이 정해져 있지 않다. 본 연구에서는 제품의 두께, 형상 그리고 유한요소 수에 따른 2차원 해석과 3차원 해석을 비교하였다. 그리고 실험을 통해 얻은 캐비티 내의 압력과 온도를 해석결과와 비교하였다. 본 연구를 통하여 사출성형의 2D해석과 3D해석에 대한 가이드라인을 제시하고자 하였다.

• Restorative Dentistry and Endodontics
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• 제17권1호
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• pp.141-152
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• 1992

Four endodontic instruments from different manufacturers(K - file, Hedstrom - file, K - flex - file, Cavi - Endo) were used to shape 80 mesial canals of extracted posterior teeth. The instrument's ability to enlarge and shape the canals as the original canal shape was assessed by superimposing radiographs of canals obtained before and after canal shaping. The results were as follows 1. Hedstrom - file enlarged canals greater than K - file, K - flex - file, and Cavi - Endo(P<0.05). There are no differences in canal enlargement among K - flex, K - flex - file, and Cavi - Endo(P<0.05). 2. All the instruments showed no difference in canal enlargement between convex side and concave side of B point in proximal and clinical radiographic views, but at the concave side of C point canals were enlarged greater than at the convex side(proximal view of K - file: P<0.05, the others: P<0.01). 3. There was no difference m canal enlargement between convex side and concave side in proximal view of A and D points of K - file and K - flex - file(P<0.05). But in clinical view, canal enlargement at convex side of A point and concave side of D point was greater than that at concave side of A point and convex side of D point respectively. 4. Hedstrom - files showed greater canal enlargement at convex side of A points and concave side of D points (P<0.05 or P<0.01). Cavi - Endo showed no difference in canal enlargement between convex side and concave side at A and D points in proximal view(P<0.05). Bur canal enlargement was greater at concave side than at convex side of D point in clinical view. 5. K - file and Cavi - Endo showed no differences in canal enlargement between convex and concave side in proximal and clinical view (P<0.05). K - flex - file showed greater canal enlargement at concave side in proximal and clinical view(P<0.0:5). Hedstrom file showed no difference in canal enlargement between convex side and concave side in proximal view, but showed greater canal enlargement at concave side in clinical view(P<0.05).