• 동력기계공학회지
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• 제16권4호
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• pp.24-29
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• 2012

The numerical analysis by using CFX 11.0 commercial code was done for prediction of fluid flow and thermal field in the vertical heat exchanger. The present experimental studies were also conducted to investigate the effects of circulating solid particles on the fluid flow and temperatures in the fluidized bed vertical shell and tube type heat exchanger with counterflow, at which the solid particles of glasses (3 $mm{\Phi}$) were used in the fluidized bed with a smooth tube. The effect of circulation on the distance(L) of tube inlet and baffle plate was also examined. The present experimental and numerical results showed that the particles in the distance (Ds) of 15 mm showed a more efficient circulation without stacked the space and the LMTD(Log Mean Temperature Difference) in the fluidized bed type was much lower than that in the typical type shell and tube heat exchanger.

• 한국농공학회논문집
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• 제53권4호
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• pp.21-27
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• 2011

Soil stress distribution under loading is one of the important problems in civil engineering. Many models have been proposed to interpret the stress distribution in soil and most models assume that the soil is homogeneous and isotropic. Therefore, the actual stress distribution may be different. In addition, With the increase of the top load, soil stress does not increase linearly. In this study, vertical stress changes in sandy soil according to top load increase were measured through experiments. Experimental results, vertical soil stress due to top load increase showed an initial nonlinear behavior and when the load increases to some extent, vertical soil stress showed a linear behavior. ${\alpha}$ value obtained by existing theories always 1.00. But, ${\alpha}$ value by experiment was observed from 0.91 to 1.22 and ${\alpha}$ value was increased with increasing distance from the loading plate.

• 한국해안해양공학회지
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• 제16권1호
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• pp.1-9
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• 2004

본 연구에서는 원전어항에서 채용하고 있는 강제 부방파제에 비해 소요재료량의 변화가 크지 않은 범위에서 전후연직판의 위치와 형식의 변화 및 수평판의 부착 유무에 따른 여러 형식의 부방파제에 의한 투과율과 반사율을 Green 함수법으로부터 계산한 결과에 기초하여, 원전어항의 강제 부방파제보다 단주기파 및 장주기파를 보다 효과적으로 제어할 수 있는 새로운 형식의 부방파제를 검토하였다. 이로부터 연직커튼판 하부에 수평판을 부착한 형태의 부방파제가 파랑제어기능이 우수한 것으로 판명되었고, 이는 원전어항 부방파제보다 파랑제어기능이 탁월하다는 것을 알 수 있었다. 또한, 본체에 부착된 전후연직판 및 수평판의 크기와 간격을 조절함으로써 적합한 투과파를 얻을 수 있다는 것도 알 수 있었다.

• Journal of Welding and Joining
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• 제26권5호
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• pp.66-73
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• 2008

Welding work in pre-erection or erection stage of shipbuilding construction to be carried out in flat and vertical upward position mostly and Electrogas welding(EGW) is actively applied especially for vertical butt joint of thicker steel plate recently. In this study considered how to develope and improve mechanical properties of weld metal and HAZ in high heat input welding processes such as EGW and Electroslag welding(ESW) with its welding equipment in order to extend the application range to the longitudinal members and hatch coaming parts of container ship. Some components of welding system and parameters were modified to get the faster travel speed and reduce weld heat input, and also by adding additional filler rods or tubes increase the amount of deposited weld metal. With the test get some good date can apply to actual fabrication work and recommend items to manufacture welding materials make better. Above all things it's a fruition that to prepare the possibility of application of ESW to shipbuilding construction which fill up the gap of stoppage days of more than 20 years.

• 한국멀티미디어학회논문지
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• 제8권11호
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• pp.1449-1461
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• 2005

본 논문에서는 차량의 식별마크 분류 및 차량번호판 인식을 통한 차량인식 알고리즘을 제안하였다. 제안한 알고리즘에서는 먼저 입력 차량영상으로 부터 잡음제거, 세선화 과정 등 전처리 과정들을 수행하고 명암값 변화 빈도 분포를 사용하여 차량식별마크와 번호판 영역을 추출하였다. 또한 추출된 후보 영역으로부터 차량 식별마크와 번호판 영역의 구조적 특성 정보를 사용하여 차량 식별마크, 번호판의 문자 및 숫자를 분류하였으며, 하이브리드 패턴벡터 및 수직수평 패턴벡터를 사용하여 식별마크, 문자 및 숫자를 인식하여 차량 정보 인식율을 개선하였다. 제안한 알고리즘에서는 차량의 식별마크가 차량의 종류에 따라 독립적인 특성, 식별마크와 번호판 영역에서는 문자와 배경이 뚜렷하게 구별되는 특성 및 수평 및 수직빈도수 분포가 식별마크 및 번호판 이외의 영역과 뚜렷이 구별된다는 특성들을 이용하였다. 제안한 방법의 성능을 확인하기 위하여 다양한 환경에서 촬영된 350여개의 영상에 대하여 차량인식 실험을 수행하였고 제안한 방법이 차량번호판의 크기와 위치에 무관하고 잡음의 영향에 덜 민감하였을 뿐만 아니라 불규칙적인 외부환경에서도 인식율이 개선되었다. 또한 식별마크와 번호판 인식의 실시간 처리가 가능하여 실제 주차장이나 도시화도로등에 적용이 가능하다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제28권1호
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• pp.1-6
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• 2002

When bilateral sagittal split ramus osteotomy or mandibular angle reduction are carried out, we have to consider the position of inferior alveolar nerve. For bone splitting or resection using a saw or an osteotome, the bucco-lingual position of the inferior alveolar nerve plays an important role in the preventing perioperative complications such as paresthesia or anesthesia. Because it is rare to find literatures concerning the mean anatomic position of the inferior alveolar nerve in Koreans, we investigated 30 patients who underwent to take CT and orthopantomogram for implant surgery, and evaluated the bucco-lingual position and vertical relationship of the inferior alveolar nerve at the mandible. The results showed that the distance between inferior alveolar nerve and buccal plate was the farthest at mandibular second molar ($7.1{\sim}7.4mm$) and the nearest at mandibular angle area ($4.4{\sim}4.8mm$). But it was no statistical relationship between the bucco-lingual postion of inferior alveolar nerve on the CT and its vertical position on the OPT. In conclusion, the results suggest that a careful surgical procedure is needed at the mandibular angle area to avoid a nerve damage and there are sufficient bone materials at the mandibular second molar are for bilateral sagittal split ramus osteotomy or mandibular angle reduction or plate fixation. And OPT is not usefull for the evaluation of a relative bucco-lingual position of inferior alveolar nerve in relation to its vertical postion on the OPT.

• Steel and Composite Structures
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• 제25권6호
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• pp.671-684
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• 2017

Elastic-plastic shear buckling behaviors of the web-post in a Castellated Steel Beam (CSB) with hexagonal web openings under vertical shear force were investigated further using Finite Element Model (FEM) based on a sub-model, which took the upper part of the web-post under horizontal shear force to represent the whole web-post under vertical shear force. A simplified design method for the web-post elastic-plastic shear buckling strength was proposed based on simulation results of the sub-model. Proper boundary conditions were applied to the sub-model to assure that its behaviors were identical to those of the whole web-post. The equation to calculate the thin plate elastic shear buckling strength was adopted as the basic form to build the design equation for elastic-plastic buckling strength of the sub-model. Parameters that might affect the elastic-plastic shear buckling strength of the whole web-post were studied. After obtaining the vertical shear buckling strength of a sub-model through FEM, the shear buckling coefficient k can be obtained through the back analysis. A practical calculation method for k was proposed through curving fitting the parameter study results. The elastic-plastic shear buckling strength of the web-post calculated using the proposed shear buckling coefficient k agreed well with that obtained from the FEM and test results. And it was more precise than those obtained from EC3 based on the strut model.

• 한국구조물진단유지관리공학회 논문집
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• 제27권1호
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• pp.95-102
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• 2023

본 연구에서는 다양한 래티스 단부 지점조건을 갖는 철선일체형 데크플레이트의 구조성능을 유한요소해석을 통하여 평가하였다. 해석결과, 래티스 단부에서 풋의 위치가 지점부 구조부재 위에 위치하는 경우가 그렇지 않은 경우에 비해 시스템 강성이 더 큰 것으로 나타났다. 또한 래티스 풋이 지점부에 위치하는 경우, 단부 직봉이 전체 데크플레이트 시스템의 강성과 강도에 미치는 영향은 무시할 정도로 작았다. 특히 래티스 풋의 길이가 40mm 보다 작지 않을 때에는 단부 직봉이 설치되지 않아도 무방한 것으로 평가되었다. 래티스 단부 지지형상이 데크플레이트 시스템의 최대 하중저항 성능에 미치는 영향은 크지 않은 것으로 조사되었고, 시스템의 파괴모드는 설계의도에 따라 데크플레이트 중앙에서 상부 주철근의 좌굴, 래티스 단부 좌굴, 또는 이들의 조합으로 나타났다.

• 대한토목학회논문집
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• 제32권5A호
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• pp.267-275
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• 2012

본 연구에서는 철근 콘크리트 벽과 강판 콘크리트 벽이 이질접합 형태로 만나는 구조물의 휨 및 전단거동 특성을 검토하기 위하여 L형과 I형 타입의 실험체를 제작하고 구조실험을 수행하였다. 실험 시, 지진하중 등에 대한 실험체의 동적특성을 확인하기 위하여 Push 및 Pull을 반복하는 싸이클 하중을 구현하고자 하였다. L형 실험체에 대한 면외 휨 실험결과, 실험체의 공칭강도를 초과하는 휨 성능을 발휘하였으며, 이에 따라 설계에 적용된 수직철근의 미겹침 이음길이의 타당성을 확인할 수 있었다. 한편, 강판 콘크리트 벽 내에 수평철근의 배근 유무를 변수로 구성한 두 개의 I형 실험체에 대한 면내 전단 실험결과, 수평철근의 배근 유무에 상관없이 공칭강도를 초과하는 전단 성능을 보였다.

• 대한치과보철학회지
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• 제37권5호
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• pp.607-619
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• 1999

Cortical support is an important factor, as the engagement of the fixture in strong compact bone offers an increased load-carrying capacity and initial stability. Because of the poor bone quality in the posterior mandible and other anatomic considerations, it has been suggested that implant fixtures be placed in these locations with apical engagement of the lingual cortical plate for so-called bicortication. The purpose of this investigation was to determine the effect of cortical engagements and in addition polyoxymethylene(POM) intramobile connector(IMC) of IMZ implant on implant load transfer in edentulous posterior segment of mandible, using three-dimensional (3D) finite element analysis models composed of cortical and trabecular bone involving single implant. Variables such as (1) the crestal peri-implant defect, (2) the apical engagement of lingual cortical plate, (3) the occlusal contact position (a vertical load at central fossa or buccal cusp tip), and (4) POM IMC were investigated. Stress patterns were compared and interfacial stresses along the bone-implant interface were monitored specially. Within the scope of this study, the following observations were made. 1) Offset load and angulation of fixture led to increase the local interfacial stresses. 2) Stresses were concentrated toward the cortical bones, but the crestal peri-implant defect increased the interfacial stresses in trabecular bone. 3) For the model with bicortication, it was noticed that the crestal cortical bone provided more resistance to the bending moment and the lingual cortical plate provided more support for the vertical load. But Angulation problem of the fixture from the lingual cortical engagement caused the local interfacial stress concentrations. 4) It was not clear that POM IMC had the effect on stress distribution under the present experimental conditions, especially for the cases of crestal peri-implant defect.