• Journal of Mechanical Science and Technology
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• 제15권5호
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• pp.671-680
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• 2001

Boundary condition is one of the major factors to influence the numerical stability and solution accuracy in numerical analysis. One of the most important physical boundary conditions in the flowfield analysis is the wall boundary condition imposed on the body surface. To solve a two-dimensional Euler equation, totally four numerical wall boundary conditions should be prescribed. Two of them are supplied by the flow tangency condition. The other two conditions, therefore, should be prepared additionally in a suitable way. In this paper, four different sets of wall boundary conditions are proposed and then applied to solve high-speed flowfields around a quarter circle geometry. A two-dimensional compressible Euler solver is prepared based on the finite volume method. This solver hires three different upwind schemes; Steger-Warmings flux vector splitting, Roes flux difference splitting, and Lious advection upstream splitting method. It is found that the way to specify the additional numerical wall boundary conditions strongly affects the overall stability and accuracy of the upwind schemes in high-speed flow calculation. The optimal wall boundary conditions should be also chosen very carefully depending on the numerical schemes used to solve the problem.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2003년도 학술대회지
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• pp.504-508
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• 2003

최근 공정관리와 원가관리의 중요도 인식에 기인하여 공정/원가 통합관리 및 공정정보와 3차원 설계정보를 연계할 4차원 설계 정보 연구가 활성화되고 있다. 공정과 원가를 통합할 수 있는 EVMS의 관리적 효과와 도형정보와 공정관리를 통합을 통하여 일정관리의 편의 및 효율을 극대화 하는 4차원 CAD(4D CAD)의 시각적 효과를 통합하는 4D-EVMS는 프로젝트 관리의 중요한 도구가 될 수 있다. 이러한 맥락에서, 본 연구의 목적은 발주자 공정/원가 총합관리를 위한 기본요건 도출 및 구현방안 제시에 있다. 이러한 연구의 결과물은 발주자 공정/원가관리의 업무효율 증대뿐만 아니라 실적자료 축적 및 홍보 관점에서도 기대효과를 가진 수 있을 것으로 판단된다.

• 한국자기공명학회논문지
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• 제21권3호
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• pp.102-108
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• 2017

Escherichia coli responds to ever-changing external and internal stresses by rapidly adjusting its physiology for better survival. This adjustment occurs at all levels including metabolites as well as mRNAs and proteins. Although there has been many reports describing E. coli's adaptation to various stresses regarding transcriptomics or proteomics, only a few investigations have been reported regarding this adaptation viewed from metabolites' perspective. We applied four different types of stresses at four different doses as imposed by NaCl, sorbitol, ethanol, and pH to investigate the similarities or differences among the stresses, and which stress causes the largest perturbation of the metabolite composition. We profiled the metabolites under such external stresses by using two-dimensional NMR spectroscopy and identified 39 metabolites including amino acids, sugars, organic acids, and nucleic acids. According to our statistical analysis, the osmotic stress caused by sorbitol differentiated itself from others, while NaCl showed the largest dose dependent metabolic perturbations. We hope this work will form a foundation on which an approach to a successful protein production is systematically provided by a favorable metabolic environment by imposing proper external stresses.

• 디지털콘텐츠학회 논문지
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• 제18권7호
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• pp.1259-1265
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• 2017

기능성 게임의 교육적 잠재력에 대한 합의가 있는 반면, 설계뿐만 아니라 분석과 평가를 지원하기 위한 방법론과 도구의 부족이 아직 존재한다. 본 논문은 기능성 게임에 요구되는 교육학 관련 연구의 분석을 통해 필요한 요소들을 알아내어 새로운 방법론 또는 설계 방향을 모색하려는 의도를 가진다. 이를 위해 4DF(Four Dimensional Framework), GOM(Game Object Model), LM(Learning Mechanics)-GM(Game Mechanics), 교사용 프레임워크에 대한 분석을 하였다. 교육적 게임이 직면한 가장 큰 쟁점 중의 하나는 교육과 게임 원리의 부적절한 통합에 있다. 이것은 게임 설계자와 교육 전문가가 공통적인 어휘나 업무영역의 관점을 공유하지 않는다는 사실을 포함하여 다양한 요인에 기인한다.

• 한국식품영양과학회지
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• 제28권6호
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• pp.1269-1274
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• 1999

Four dimensional response surface methodology was applied to determine the optimum conditions on organoleptic properties to develop red pepper jam into Korean type jam. The organoleptic color of red pepper jam showed maximum score of 8.08 in 14.24g pectin, 256.2g sucrose and 8.31ml citric acid(50% citric acid solution). The organoleptic taste of red pepper jam showed maximum score of 6.77 in 14.23g pectin, 202.1g sucrose and 8.19ml citric acid. Optimum conditions on the organoleptic mouth feel of red pepper jam were 14.34g in pectin, 255.6g in sucrose and 8.39ml in 50% citric acid solution. Maximized overall palatability of red pepper jam was 7.25 in 14.15g pectin, 257.08g sucrose and 8.19ml of 50% citric acid solution. The optimum preparation condition ranges on organoleptic properties of red pepper jam were 14.0~15.5g pectin, 225.0~257.0g sucrose and 8.0~8.2ml of 50% citric acid solution.

• 한국대기환경학회지
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• 제25권4호
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• pp.264-274
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• 2009

Concentration of Air Quality Models (CMAQ) has a deep connection with emissions and wind fields. In particular the wind field is highly affected by local topography and plays an important role in transport and dispersion of contaminants from the pollution sources. The purpose of this study is to examine the impact of interpolation on Air quality model. This study was designed to evaluate enhancement of MM5 and CMAQ predictions by using Four Dimensional Data Assimilation (FDDA), the SONDE data and the national meteorological station and the MODerate resolution Imaging Spectroradiometer (MODIS). The alternative meteorological fields predicted with and without MODIS data were used to simulate spatial and temporal variations of ozone in combined with CMAQ on June 2006. The result of this study indicated that data assimilation using MODIS data provided an attractive method for generating realistic meteorological fields and dispersion fields of ozone in the Korea peninsular, because MODIS data in 10 km domain are grid horizontally and vertically. In order to ensure the success of Air quality model, it is necessary to FDDA using MODIS data.

• 한국추진공학회지
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• 제12권3호
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• pp.68-75
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• 2008

이전에 개발된 병렬 해석 코드를 이용하여 원형 관내에서의 삼차원 데토네이션 파 전파 특성을 관찰 하였다. 일련의 해석을 통하여 직경이 일정한 원형 관에서 반응 속도 상수 값 k에 의존하는 데토네이션 셀 생성 메커니즘을 알 수 있었다. 삼차원 유동에 대한 비정상 유동의 해석 결과는 two-, three-, four-cell 구조의 메커니즘을 잘 보여주었으며, 반응속도 상수 k가 증가함에 따라 생성되는 셀 수가 증가하고 셀의 폭과 길이는 감소하였다. 모든 다중-셀 모드에서 데토네이션 파의 구조와 그을음막 기록은 횡단파의 움직임에 의하여 만들어지며, 데토네이션 파면은 주기적으로 일정한 다각형 및 풍차 형상을 가지게 된다.

• Journal of Chest Surgery
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• 제19권3호
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• pp.506-514
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• 1986

Coarctation of aorta is rather common congenital cardiovascular defect in the western countries, but it is known to be rare in Korea. And no coarctation of Aorta has been reported and operated upon during early infancy in Korea. During 4 months period from May 1984 to September 1984, four small infants of coarctation of aorta were seen and treated surgically by subclavian flap aortoplasty in Guro Hospital, Korea University. All infants were male, ranging from 7 days to 54 days old [mean 29 days], weighing between 3.2 Kg and 5.0 Kg [mean 4.1 Kg], and all were in congestive heart failure. Examination of the femoral artery pulse gave in all cases clues to the diagnosis. By Two dimensional echocardiogram, detail anatomical features as well as the diagnosis were revealed and associated anomalies, for example, ventricular septal defect could be seen. Besides one case of isolated coarctation of aorta, other three infants had associated VSD. The 3 patients with VSD were treated by pulmonary artery banding in addition to aortoplasty. The postoperative course were smooth in all patients. In conclusion, coarctation of aorta may not be so rare in Korea as we thought previously. The importance of femoral pulse examination can not be overemphasized for the diagnosis. As we experienced, two-dimensional echocardiography in most cases can substitute those invasive examinations such as angiography and catheterization which carry difficulty and risk in infants.

• 한국분말재료학회지
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• 제23권2호
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• pp.149-169
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• 2016

Additive manufacturing (AM) is defined as the manufacture of three-dimensional tangible products by additively consolidating two-dimensional patterns layer by layer. In this review, we introduce four fundamental conceptual pillars that support AM technology: the bottom-up manufacturing factor, computer-aided manufacturing factor, distributed manufacturing factor, and eliminated manufacturing factor. All the conceptual factors work together; however, business strategy and technology optimization will vary according to the main factor that we emphasize. In parallel to the manufacturing paradigm shift toward mass personalization, manufacturing industrial ecology evolves to achieve competitiveness in economics of scope. AM technology is indeed a potent candidate manufacturing technology for satisfying volatile and customized markets. From the viewpoint of the innovation technology adoption cycle, various pros and cons of AM technology themselves prove that it is an innovative technology, in particular a disruptive innovation in manufacturing technology, as powder technology was when ingot metallurgy was dominant. Chasms related to the AM technology adoption cycle and efforts to cross the chasms are considered.

• 디지털융복합연구
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• 제11권11호
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• pp.313-320
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• 2013

본 논문에서는 가상현실상의 내리막이나 오르막 상황, 경사도 또는 노면 상태를 그대로 인식할 수 있는 사이클 시뮬레이터를 개발하였다. 개발된 시뮬레이터는 전방에 설치되어 있는 LCD 모니터를 통해 디스플레이 되는 다양한 가상 운동경로의 상황에 맞추어 종전 운동용 사이클의 단조롭고 지루한 단점을 개선하였다. 또한 적절한 운동량과 재미요소를 추가하여 현실감과 게임의 재미를 느낄 수 있는 4D 사이클링 콘텐츠를 개발하였으며, 흥미 유발형 운동기기에 대한 사용자 편의성을 위한 기초 신체 능력에 대한 분석 및 평가 하였다.