• 대한기계학회논문집A
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• 제33권9호
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• pp.903-912
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• 2009

This study is focused on simulation-based dimensional tolerance optimization process (DTOP) to minimize vehicle pulls by reduction of dimensional variation in front suspension system. In previous studies, the effect of tires and wheel alignment sensitivity have mainly been investigated to eliminate vehicle pulls in nominal design condition without allocating optimal tolerance level for selected components, among various factors regarding vehicle pulls such as vehicle design parameters, vehicle weight balance, tires, and environmental factors. Unfortunately, there are wide variations in the real vehicle, and these have impacted actual vehicle pulls, especially wheel alignment effects from suspension geometry variation has not been considered in the previous studies. In the tolerance design of suspension, tolerance variables with the uncertainty such as parts dimensional variation, assembly process, datum position and direction, and assembly tool tolerance has a great influence on the variation of the suspension dimensional performances. This study introduces total vehicle pull prediction model in considering major key factors for vehicle pull sensitivity. The Monte Carlo-based tolerance analysis model using Taguchi robust method is developed to optimize dimensional tolerance parameters, satisfying on the target variation level.

• 물과 미래
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• 제25권1호
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• pp.111-119
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• 1992

간척사업에 있어 용수원이 되는 깊은 담수화호에서는 체절후 온도 및 염분농도차에 의한 이층류가 발생하게 되며 이중 저층염분수는 밀도류 흐름의 구조특성상 배수\ulcorner문만으로 배제가 어려우므로 별도의 저층배수시설을 계획하여 담수호화를 촉진하고 있다. 성층화된 담수화호에서 상층부의 염도변화에 영향을 주는 요소로는 크게 나누어 세가지로 대별한다. 첫째는 상, 하층간의 밀도차에 의한 내부경계면의 난류현상, 둘째는 상층부의 흐름과 요동(바람,파)에 의한 혼합작용, 셋째는 하층부 호저토에서 발생되는 염분의 확산이다. 따라서 담수호화 모형을 위한 이층류흐름의 염분평행방정식을 구획하고 이 모형이 가지는 여러 가지 매개변수를 현장에서 실측된 염분농도변화에 부합하도록 유도하였다.

• 수산해양교육연구
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• 제26권3호
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• pp.535-542
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• 2014

The purpose of this study was to analyze the movements of the lower extremity joints during a taekwondo kick motion called 'Juchumseogi hu Apkkoaseogi yeopchagi', which was administered to players to improve their balance, stability, and range of motion for the prevention of injuries. Eight professional players and amateur players were recruited as the subjects. Kinematic data were collected by four real-time infrared cameras. The hip joint, knee joint, and ankle joint angles were measured using instruments. During the 'Juchumseogi hu Apkkoaseogi yeopchagi' kick motion, there were small and inconsistent effects on each joint. This study processed the data using the Windows SPSS Ver. 18.0 to get an independent t-test, with the setting, p< .05. Results indicated that hip joint, knee joint, and ankle joint angles were almost significantly different between professional and amateur player during 'Juchumseogi hu apgeule Apkkoaseogi' kick motion.

• 한국정밀공학회지
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• 제18권12호
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• pp.60-65
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• 2001

To simulate the real molding conditions, the effects of phase change and compressibility of the resin were considered in the present investigation. A modified Cross model with either an Arrhenius-type or WLF-type functional form was used for modeling viscosity of the resin. A double-domain Tait equation of state was employed to describe the compressibility of the resin during molding. The energy balance equation including latent-heat dissipation fur semi-crystalline materials was solved in order to predict the solidified layer and temperature profile. Injection molding experiments were carried out using polypropylene(PP) in the present study. Based on the comparison between experiments and simulations, it was found out the predicted pressure distributions and melt front propagations were accurate. Thus it was concluded that the program developed in this study was proved to be useful in simulations of injection molding process.

• Nuclear Engineering and Technology
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• 제36권6호
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• pp.528-539
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• 2004

It is essential in commercial reactors that the safety limits imposed on the fuel pellets and fuel clad barriers, such as the linear power density (LPD) and the departure from nucleate boiling ratio (DNBR), are not violated during reactor operations. In order to accurately monitor the safety limits of current reactor states, a detailed three-dimensional (3D) core power distribution should be estimated from the in-core detector signals. In this paper, we propose a calculation methodology for detailed 3D core power distribution, using in-core detector signals and core monitoring constants such as the 3D Coupling Coefficients (3DCC), node power fraction, and pin-to-node factors. Also, the calculation method for several core safety parameters is introduced. The core monitoring constants for the real core state are promptly provided by the core design code and on-line MASTER (Multi-purpose Analyzer for Static and Transient Effects of Reactors), coupled with the core monitoring program. through the plant computer, core state variables, which include reactor thermal power, control rod bank position, boron concentration, inlet moderator temperature, and flow rate, are supplied as input data for MASTER. MASTER performs the core calculation based on the neutron balance equation and generates several core monitoring constants corresponding to the real core state in addition to the expected core power distribution. The accuracy of the developed method is verified through a comparison with the current CECOR method. Because in all the verification calculation cases the proposed method shows a more conservative value than the best estimated value and a less conservative one than the current CECOR and COLSS methods, it is also confirmed that this method secures a greater operating margin through the simulation of the YGN-3 Cycle-1 core from the viewpoint of the power peaking factor for the LPD and the pseudo hot pin axial power distribution for the DNBR calculation.

• Wind and Structures
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• 제18권4호
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• pp.423-441
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• 2014

The high frequency base balance (HFBB) technique is a convenient and relatively fast wind tunnel testing technique for predicting wind-induced forces for tall building design. While modern tall building design has seen a number architecturally remarkable buildings constructed recently, the characteristics of those buildings are significantly different to those that were common when the HFBB technique was originally developed. In particular, the prediction of generalized forces for buildings with 3-dimensional mode shapes has a number of inherent uncertainties and challenges that need to be overcome to accurately predict building loads and responses. As an alternative to the more conventional application of general mode shape correction factors, an analysis methodology, referred to as the linear-mode-shape (LMS) method, has been recently developed to allow better estimates of the generalized forces by establishing a new set of centers at which the translational mode shapes are linear. The LMS method was initially evaluated and compared with the methods using mode shape correction factors for a rectangular building, which was wind tunnel tested in isolation in an open terrain for five incident wind angles at $22.5^{\circ}$ increments from $0^{\circ}$ to $90^{\circ}$. The results demonstrated that the LMS method provides more accurate predictions of the wind-induced loads and building responses than the application of mode shape correction factors. The LMS method was subsequently applied to a tall building project in Hong Kong. The building considered in the current study is located in a heavily developed business district and surrounded by tall buildings and mixed terrain. The HFBB results validated the versatility of the LMS method for the structural design of an actual tall building subjected to the varied wind characteristics caused by the surroundings. In comparison, the application of mode shape correction factors in the HFBB analysis did not directly take into account the influence of the site specific characteristics on the actual wind loads, hence their estimates of the building responses have a higher variability.

• 디지털융복합연구
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• 제13권2호
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• pp.381-391
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• 2015

본 연구는 장애인 재활을 위해 최신 공학기술과 재활프로그램을 융합한 가상현실 기술의 효과에 관련된 연구동향을 분석한 문헌연구이다. 2000~2014년에 발표된 국내 논문 60편을 대상으로 P.I.C.O방법을 준용하여 분석한 결과, 주로 성인 노인 뇌졸중 환자를 대상으로 가상현실을 적용한 장애인 재활 프로그램 관련 연구가 많았으며, 가상현실 구현을 위해 투사형 시스템이 자주 사용되었다. 중재효과 확인을 위한 종속변수로는 균형, 상지기능, 보행이 주로 사용되었고 이를 ICF의 구성요소로 재해석하여 도출한 연구주제로는 이동이 가장 많았다. 반면 교육, 직업, 여가 등 참여영역을 다룬 연구는 매우 적었다. 향후 장애인의 실생활에 유용한 가상현실 중재를 위해서는 사회적 관점에 초점을 두어야하며, 동시에 가상현실 기술의 개발 시에도 적용방법과 비용 측면에서 용이한 접근을 염두에 두고 공학기술과 재활서비스가 융합되어야 할 것이다.

• Molecules and Cells
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• 제37권11호
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• pp.827-832
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• 2014

The balance between bone formation by osteoblasts and destruction of mineralized bone matrix by osteoclasts is important for bone homeostasis. The increase of osteoclast differentiation by RANKL induces bone diseases such as osteoporosis. Recent studies have shown that insulin is one of main factors mediating the cross-talk between bone remodeling and energy metabolism. However, the systemic examination of insulin-induced differential gene expression profiles in osteoclasts has not been extensively studied. Here, we investigated the global effects of insulin on osteoclast precursors at the level of gene transcription by microarray analysis. The number of genes that were up-regulated by ${\geq}1.5$ fold after insulin treatment for 6 h, 12 h, or 24 h was 76, 73, and 39; and 96, 83, and 54 genes were down-regulated, respectively. The genes were classified by 20 biological processes or 24 molecular functions and the number of genes involved in 'development processes' and 'cell proliferation and differentiation' was 25 and 18, respectively, including Inhba, Socs, Plk3, Tnfsf4, and Plk1. The microarray results of these genes were verified by real-time RT-PCR analysis. We also compared the effects of insulin and RANKL on the expression of these genes. Most genes had a very similar pattern of expressions in insulin- and RANKL-treated cells. Interestingly, Tnfsf4 and Inhba genes were affected by insulin but not by RANKL. Taken together, these results suggest a potential role for insulin in osteoclast biology, thus contributing to the understanding of the pathogenesis and development of therapeutics for numerous bone and metabolic diseases.

• 자원ㆍ환경경제연구
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• 제33권1호
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• pp.1-32
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• 2024

배출권거래제는 대표적인 기후정책으로 온실가스 총배출량의 87%(2021년 기준)에 대한 감축 유인체계를 형성한다. 상당량의 감축이 기대되는 가운데 배출권가격 변동이 경제, 에너지 및 환경 부문에 미칠 파급 효과에 대한 심도있는 이해가 필요하다. 본 고는 거시계량 기반 연립방정식 모형을 통해 배출권거래제의 정책효과를 분석한 국내 최초의 연구로, 한국표준산업분류(경제), 에너지밸런스(에너지), 국가온실가스인벤토리(환경)를 연결해 현실 설명력을 제고한 데 의의를 지닌다. E3 동학에 대한 분석결과에 따르면 4년에 걸친 배출권가격의 50% 인상 충격은 온실가스 배출량 감소(-0.043%)와 함께 주요 거시변수인 실질GDP(-0.058%), 민간소비(-0.003%) 및 투자(-0.301%) 등의 하방 이동으로 귀결된다. 배출권가격의 인상은 온실가스 감축목표 달성의 필수불가결한 요소로, 가격 인상 충격에 따른 이행리스크에 대응함으로써 거시 경제의 지속가능성을 담보하기 위해 경매수익을 활용한 세수환원 방안을 검토할 수 있다. 본 연구는 법인세 경감 및 경상이전지출 확대 등 세수환원 수단 중 성장 측면에서 후자의 정책 비교우위를 확인했다.

• 한국콘텐츠학회논문지
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• 제21권1호
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• pp.147-161
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• 2021

기존 연구는 대부분 사진측량(Photogrammetry)기술을 이용해 물체의 투박한 3D메시와 컬러 맵을 획득하였을 뿐, 실제로 사용 가능한 사실적인 3D 에셋을 제작하는 방법은 제시하지 못했다. 본 연구의 목적은 새로운 방법을 제시하여 가시화 애플리케이션 분야에 사용 가능한 사실적인 3D 에셋(Asset)을 구축 가능하게 하는 데 있다. 여기에서 언급한 새로운 방법이란 사진 측량과 컴퓨터 그래픽(Computer Graphics)의 모델링 과정을 결합하는 것이다. 현실 세계의 세 물체 '탄알상자', '총', '금속 음료수병'을 가상 세계에서 사실적인 3D에셋으로 제작하는 과정을 통해 오브젝트 촬영, 화이트 밸런스, 재건, 정리 재건, 리토폴로지, UV 언래핑, 프로젝션 및 텍스처 베이킹, 디라이팅, 재질 맵 제작 등 절차의 정의, 역할, 조작방법과 사용된 소프트웨어 패키지(Software Package)를 상세히 소개하였다. 제작 방법의 유연성을 높이기 위해 각 단계별로 소개된 소프트웨어 패키지외의 대안도 제시하였다. 본 연구는 형태와 색상이 정확하고, 텍스처가 동적광원(Dynamic Lighting)과 물리적 인터랙션이 가능하며, 렌더링이 용이한 3D 에셋을 획득함으로써 새로운 방법을 통해 더 빠른 속도로 더 실감나는 시각효과를 실현할 수 있다는 것을 보여주고 있다. 대규모 팀, 값비싼 설비와 소프트웨어 패키지가 필요 없기 때문에 소형스튜디오에서 독립적 아티스트의 창작과 교육으로 구성된 수업에 적용하기 적합하다.