• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권1호
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• pp.34-40
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• 2012

Purpose: The study was performed to compare patients with anatomical variations in facial asymmetry with patients in the normal range using cone-beam computed tomography (CBCT) and to take the preoperative condition into consideration in the case of a sagittal split ramus osteotomy (SSRO). Methods: The study was conducted on 46 adult patients composed of 2 subdivided groups, an asymmetry group (n=26) and a symmetry group (n=20). The asymmetry group was divided between patients with hemimandibular hyperplasia (HH, n=8) and hemimandibular elongation (HE, n=18). Using cross-sectional computed tomography images, the thickness of cancelleous bone in the buccal area of the mandible, thickness of buccal cortex in the buccal aspect of the mandible, thickness of cancellous bone in the inferior aspect of the mandible, thickness of buccal cortex in the inferior aspect of the mandible, and cross-sectional surface area of the mandible were measured. Results: In the asymmetry group, the cross-sectional area of the mandible including the inferior alveolar nerve positioned on the affected side was significantly different from the symmetry group. Thickness of cancelleous bone in the buccal aspect of the mandible, thickness of cancelleous bone in the inferior aspect of the mandible, and cross-sectional surface area of the mandible in the affected site of hemimandibular hyperplasia was significantly smaller than in the symmetry group. Conclusion: The inferior alveolar nerve runs lower and in a more buccal direction and shows a smaller cross-sectional surface of the mandible in the hemimandibular hyperplasia patients with asymmetry.

• 국제강구조저널
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• 제18권5호
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• pp.1541-1559
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• 2018

This paper addresses the dynamic loading characteristics of the shock tube onto sandwich steel beams as an efficient and accurate alternative to time consuming and complicated fluid structure interaction using finite element modeling. The corrugated sandwich steel beam consists of top and bottom flat substrates of steel 1018 and corrugated cores of steel 1008. The corrugated core layers are arranged with non-uniform thicknesses thus making sandwich beam graded. This sandwich beam is analogous to a steel beam with web and flanges. Substrates correspond to flanges and cores to web. The stress-strain relations of steel 1018 at high strain rates are measured using the split-Hopkinson pressure. Both carbon steels are assumed to follow bilinear strain hardening and strain rate-dependence. The present finite element modeling procedure with an improved dynamic impulse loading assumption is validated with a set of shock tube experiments, and it provides excellent correlation based on Russell error estimation with the test results. Four corrugated graded steel core arrangements are taken into account for core design parameters in order to maximize mitigation of blast load effects onto the structure. In addition, numerical study of four corrugated steel core placed in a reverse order is done using the validated finite element model. The dynamic behavior of the reversed steel core arrangement is compared with the normal core arrangement for deflections, contact force between support and specimen and plastic energy absorption.

• 한국전산구조공학회논문집
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• 제32권3호
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• pp.141-147
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• 2019

본 논문에서는 체계적인 설계법을 통해 다중 빔 형성을 위한 빔 분배기의 설계를 소개한다. 본 연구의 목표는 산란하는 마이크로파를 다중 방향으로 진행하는 빔으로 변환시키는 빔 분배기를 설계하는 것이다. 기존의 이론 기반 접근법으로는 불특정 방향으로의 다중 빔 분배가 어렵다. 그러므로 본 연구에서는 기존의 이론 기반 접근법인 변환광학 이론이 아닌 체계적인 설계 방법인 페이즈 필드 설계법을 통해 최적의 빔 분배기 구조를 설계하였다. 목적함수는 각 방향으로 특정 지점의 전기장 세기의 표준값을 최대화로 설정하였다. 섬 형상의 구조를 피하고 하나의 연결된 구조를 얻기 위해 증강된 라그랑지안을 사용하여 체적 제약조건을 설정하였다. 목표 주파수는 X-band의 주파수 대역의 10GHz이다. 설계된 최적 형상의 빔 분배기는 다중 빔 형성 성능을 잘 보였고, 목표 영역에 전달되는 전기 에너지는 증가하였다. 또한 설계가 유효한 주파수 대역을 평가하기 위해 X-band 대역에 대해 주파수 대역 성능 평가를 수행하였다.

• 한국지진공학회논문집
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• 제21권4호
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• pp.189-195
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• 2017

In the seismic design of building structural members, due to the complexity of the placement of PC steels in prestressed concrete members, it is necessary to review and define the definition of member damage in comparison with reinforced concrete members. In this study, the results of past experiments compared with the calculation results by 'section Analysis Method', with the aim of reviewing the precision of calculation results when member damage evaluation is performed using the section analysis method. Furthermore, it is also compared with the calculation results by the 'split Element Method'. In addition, parametric studies were carried out, and the influence of the difference between the amount of PC steels and reinforced bar on the residual strain was examined.

• 한국수산과학회지
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• 제44권4호
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• pp.390-396
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• 2011

Southern rough shrimp Trachysalambria curvirostris is exploited mainly by small shrimp beam trawl in coastal regions of Korea. To determine the size selectivity of a shrimp beam trawl for this species, a series of comparative fishing experiments was conducted in the sea adjacent to Geoje Island off the southern cost of Korea in June and November, 2010, using codends with four different mesh sizes(14.2, 17.8, 25.5, and 35.3 mm). The extended Share Each Length's Catch Total(SELECT) analysis method, based on a multinomial distribution, was applied to the fishing data to obtain a master selection curve. The model with the estimated split parameters fit the catch data best. The master selection curve was estimated to be: s(R)=exp(15.183R-7.872)/[1+exp(15.183R-7.872)], where the relative carapace length, R, is the ratio of carapace length to mesh size. The relative carapace length for 50% retention was 0.518, and the selection range was 0.145. The results suggest that codends with a larger mesh size allow more small-sized shrimps to escape.

• Coupled systems mechanics
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• 제8권1호
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• pp.1-17
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• 2019

The present paper deals with delamination fracture analyses of the multilayered functionally graded non-linear elastic Symmetric Split Beam (SSB) configurations. The material is functionally graded in both width and height directions in each layer. It is assumed that the material properties are distributed non-symmetrically with respect to the centroidal axes of the beam cross-section. Sine laws are used to describe the continuous variation of the material properties in the cross-sections of the layers. The delamination fracture is analyzed in terms of the strain energy release rate by considering the balance of the energy. A comparison with the J-integral is performed for verification. The solution derived is used for parametric analyses of the delamination fracture behavior of the multilayered functionally graded SSB in order to evaluate the effects of the sine gradients of the three material properties in the width and height directions of the layers and the location of the crack along the beam width on the strain energy release rate. The solution obtained is valid for two-dimensional functionally graded non-linear elastic SSB configurations which are made of an arbitrary number of lengthwise vertical layers. A delamination crack is located arbitrary between layers. Thus, the two crack arms have different widths. Besides, the layers have individual widths and material properties.

• 전자공학회논문지SC
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• 제44권2호
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• pp.39-45
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• 2007

본 논문에서는 multiple array 안테나 링크 상에서 각 스테이션 간의 안테나 빔의 스위트 스폿을 변형된 유전자 알고리즘을 이용하여 찾고 유지하는 방법을 제안하였다. 제안한 방식은 각 스테이션에서 전송하는 데이터에 안테나의 정보를 같이 전송하며 범의 강도를 거리함수로 나타내고 그 거리함수의 곱을 적합도 함수로 이용하여 최대값이 되는 각도를 찾는 방식이다. 변형된 유전자 알고리즘 방식은 전처리 과정을 통하여 우수한 초기세대를 선택하는 방식으로 일반적인 유전자 알고리즘방식에서 랜덤하게 초기세대를 갖는 것과는 차별화가 된다. 통식 방식은 시분할 이중화 (TDD: Time Division Duplex) 방식으로 하여 전송하는 데이터에 안테나 정보를 같이 보낸다. 제안한 방식의 유용성을 확인하기 위하여 1:1, 1:2, 1:5 array 안테나의 세 가지 경우에 대하여 시뮬레이션 하였다. 염색체의 길이는 8bit, 16bit, split인 경우에 대하여 개체 수와 세대 수를 변화시켜 수렴 확률을 비교 검토하였다. 제안한 16bit split는 실제로는 8bit이지만 16bit와 유사한 좋은 수렴율을 보여주었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기설비전문위원
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• pp.231-232
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• 2008

The surface made of dielectric materials can therefore become probable sites for damaging electrostatic discharges. Thanks to a specially equipped chandler, the spatial environment can be reproduced experimentally in the laboratory. In this paper, the behavior of high energy electrons injected in polymers such as PolyMethylMetaAcrylate (PMMA) and Kpton is studied. Results obtained by surface potential technique, pulse-electro acoustic device and a cell based on the split Faraday cup system are analyzed and discussed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.1067-1068
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• 2010

• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 2001년도 춘계 수산관련학회 공동학술대회발표요지집
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• pp.63-64
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• 2001

최근 세계 각국은 자국 이익에 우선하는 배타적 경제수역을 설정하고, EEZ경제수역에 대한 어업생물자원의 효율적 관리를 하기 위해 주요 어종별 TAC제도를 도입하고 있다. 이 제도의 시행과 관련하여 음향을 이용한 어업생물자원량의 정량적인 계측과 적정 크기 이상의 어체만을 선택하여 어획할 수 있는 어군탐지시스템의 개발 및 보급이 절실히 요구되고 있다. (중략)