• 한국해양공학회지
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• 제13권3B호
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• pp.29-37
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• 1999

Ventilation of the marine engine room is very important for the health of the workers as well as the normal operation of machines. To find proper ventilation conditions of this engine room, numerical simulation with standard k-${\epsilon}$ model was carried out. In the present study, the marine engine room is separated to two floors with porus horizontal partition and considered as a closed space with a heat source and forced ventilation ducts. The porosity of horizontal partition is found to be important. For the engine room with 2 supply ports & 2 exhaust ports, the increasing of the porosity of horizontal partition is effective to reduce the recirculation flow zone in the second floor. When the engine room is ventilated with three supply air ports & one exhaust port, the increasing of the porosity of horizontal partition is effective to reduce the recirculating flow zone in the exhaust air area, but there is a possibility of local extreme heating at the lower side of engine near bottom.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.7-8
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• 2010

비대칭 H형강이 콘크리트에 매립되어 화재에 노출되는 일반 합성 보에 비하여 내화성능이 높은 슬림플로어 공법에 대한 화재거동특성을 분석하고, 이를 기반으로 내화성능을 향상시킬 수 있는 최적 단면형상조건을 도출하고자 연구를 수행하였다. 단면형상은 휨 성능을 증진시킬 수 있는 웹 보강과 화재에 직접 노출되는 하부플렌지의 보강 방안에 대하여 화재실험을 진행하였으며, 무 보강조건과 형상변화시에 발생하는 합성플로어의 처짐을 비교 분석하여 최적 단면형상설계 조건을 도출하고자 하였다. 실험결과 웹보강방안에 비해 하부플렌지 보강시 내화성능 향상효율이 더 높은 것으로 나타났으며, 이는 화재에 직접적으로 노출되는 하부플렌지 부분에 보강을 하는 것이 급격한 온도상승으로 인한 강도저하로 인해 발생하는 변형을 보다 효율적으로 제어하기 때문으로 판단된다.

• The Journal of Advanced Prosthodontics
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• 제9권6호
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• pp.409-415
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• 2017

PURPOSE. Accurate information is essential in dentistry. The image information of missing teeth is used in optically based medical equipment in prosthodontic treatment. To evaluate oral scanners, the standardized model was examined from cases of image recognition errors of linear discriminant analysis (LDA), and a model that combines the variables with reference to ISO 12836:2015 was designed. MATERIALS AND METHODS. The basic model was fabricated by applying 4 factors to the tooth profile (chamfer, groove, curve, and square) and the bottom surface. Photo-type and video-type scanners were used to analyze 3D images after image capture. The scans were performed several times according to the prescribed sequence to distinguish the model from the one that did not form, and the results confirmed it to be the best. RESULTS. In the case of the initial basic model, a 3D shape could not be obtained by scanning even if several shots were taken. Subsequently, the recognition rate of the image was improved with every variable factor, and the difference depends on the tooth profile and the pattern of the floor surface. CONCLUSION. Based on the recognition error of the LDA, the recognition rate decreases when the model has a similar pattern. Therefore, to obtain the accurate 3D data, the difference of each class needs to be provided when developing a standardized model.

• Restorative Dentistry and Endodontics
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• 제14권1호
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• pp.25-40
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• 1989

This study was conducted to evaluate the influence of 5 microfilled composite resin to fibroblast cultivated from human pulp (age 13). Each composite resin was manually mixed and filled in cylinder. Resin filled cylinders were placed in dishes (35mm in diameter) containing 3 ml of ${\alpha}$-MEM. Filters (pore size 0.22 ${\mu}m$) to simulate dentin were also placed between the bottom of cylinder and the dish floor. Then stored in 5% $CO_2$ containing incubator for 1 and 2 weeks at the temperature 36.6 C. The results analysed after 1 and 2 weeks were as follows: 1. Experimental group except group 2, 2 weeks incubation cases showed the cytotoxicity compared to the control group in cell count. 2. After 2 week-incubation of group 1 and group 4, cell count was more decreased than 1 week cases and cytotoxicity seemed to be constantly influenced to the cell multiplication. 3. The cell growth rate of 1 week incubation in group 3 and group 5 was similar to the control group and recognized the cytotoxicities of these groups were mild. 4. The cell multiplication rate of 2 week incubation cases in group 2 was greater than control group.

• 한국강구조학회 논문집
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• 제21권6호
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• pp.637-646
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• 2009

바닥슬래브가 있는 경우 국내에서 설계되는 트러스보는 바닥 슬래브와의 합성효과를 고려하지 않고 있다. 이 연구에서는 상하현재를 H형강으로 구성한 합성트러스를 사용하여 기본적인 실험을 수행하였다. 실험에서는 합성트러스의 역학적 거동을 조사하기 위하여 전단연결재의 유무에 따른 영향을 검토하였다. 실험체로서는 철골트러스, 비합성 및 합성트러스 등으로 이루어지며 가력방법으로는 중앙집중재하와 균등휨의 두가지 방법을 사용하였다. 시어 커넥터를 사용한 합성트러스의 합성효과가 실험적으로 확인되어졌다.

• 소성∙가공
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• 제18권6호
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• pp.488-493
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• 2009

The very big springback of advanced high strength steel(AHSS) sheets invokes undesired shape defects, which can be generally eliminated by die correction or process parameter control. The springback reduction by controlling the forming process parameters is easy for the application, but limited for the bulky achievement. In this study, the effective die correction method, which obtains the modification of tool shape from the relationship between die design variable and springback, is introduced and is applied to the TWB tool of automotive side rail to show the validity and usefulness. Among the die correction trials repeatedly performed, the first trial is carried out by correcting the tool shape to the opposite direction to the springbacks of several tool sections. Next trials are done by extrapolating the springbacks of among the original tool uncorrected and the tools corrected negative amounts of the springback and by finding tool shapes without springbacks. After the angle of side wall and radius of curvature of horizontal bottom floor are chosen as design variables in the tool design of side rail, the tool shape is corrected 3 times. The accuracy of final shape within the assembly limit of 1mm and the springback reduction of 75.8% compared to the uncorrected tool are achieved.

• 한국정보통신학회논문지
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• 제16권11호
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• pp.2397-2404
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• 2012

수중에서의 통신은 해수면과 해저면 등에 의한 신호의 반사가 생겨 다중경로 현상이 발생한다. 이러한 다중경로의 영향으로 신호는 왜곡되고 원활한 수신을 방해하게 된다. 이러한 다중 경로 환경에서 본 논문에서는 수신신호의 성능을 향상시키고자 수중통신에 적합한 반복부호를 설정하였다. 적용가능한 반복부호로는 터보 부호와 LDPC 부호가 있으며, 성능 및 부호화 길이, 등화기 적용 등의 파라메타를 기반으로 수중통신에서는 터보 부호의 적용이 적합하다는 결론을 얻었다. 따라서 터보 부호 기반으로 다중경로로 인한 위상 오차 추정은 decision directed 방식을 이용하여 위상 추적을 하였다. 실제 동해 바다에서 송수신 거리가 3Km 그리고 데이터 속도를 1Kbps로 설정하여 터보 부호의 성능을 확인하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.405-410
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• 2009

This paper presents a case study that achieved both of serviceability and safety of the building through soil reinforcement and restoration around foundations subjected to serious differential settlement using D-ROG method. The building which has one basement floor and three ground floors is founded on soft ground and differential settlement occurred to the maximum extent of 678mm. The foundation type of the building is a independent mat foundation. Soil profiles consist of landfill layer, alluvial layer, weathered rock, and soft rock. The bearing layer consisting of gravel and weathered rock is located 16.0~17.0m below the bottom of the building. As a result of soil reinforcement and restoration, the recovery ratio of more than 90% can be attained with the maximum set-up of 657mm.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.59-61
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• 2013

The purpose of this study was to present the necessary data concerning the selection and development of floor-coverings in view of slipperiness by comparing the relationship between CSR measured with O-Y·PSM and RCOF calculated from the result of gait analysis. CSR was calculated from maximum tensile load(Pmax) divided by perpendicular load(785N) when pulled 18 degrees upward the moment the bottom of the slip piece contacted the surface of the test piece. RCOF was calculated based on Fy/Fz from when horizontal load reached the maximum point within the sections from the moment the front of outsole touched the test piece to when pulled off the test piece. The results from the research were as follows: (1) Range of CSR was 0.15-1.02, which meant the differences of slipperiness of the test pieces definitely showed up. (2) RCOF are inadequate to express the characteristic about the slipperiness of the floors, since there were no differences between the test pieces.

• 한국항해항만학회지
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• 제36권8호
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• pp.631-635
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• 2012

수중에서의 통신은 해수면과 해저면 등에 의한 신호의 반사가 생겨 다중경로 전달현상이 발생한다. 이러한 다중경로 전달의 영향으로 신호는 왜곡되고 원활한 수신을 방해하게 된다. 본 논문에서는 이러한 다중경로 환경에서 효율적인 패킷 설계를 위하여 채널 부호화 기법으로는 부호화 후의 크기 N = 1944 비트, 전송하고자 하는 데이터의 크기 K = 972 비트를 가지는 부호화율 1/2 인 LDPC(Low Density Parity Check codes) 부호를 이용하였으며, 다중경로로 인한 위상 오차 추정은 decision directed 방식을 이용하여 위상 추정을 하였다. 실제 동해 바다에서 송수신 거리가 200m, 500m 그리고 데이터 속도를 1Kbps, 4Kbps로 설정하여 각 거리 및 데이터 속도에 따른 QEF(Quasi Error Free)가 되는 지점에서의 최적의 패킷 구성을 위한 데이터 길이를 제시하였다.