• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계 학술대회논문집(수송기계편)
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• pp.134-139
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• 2005

This paper presents a robust design of vehicle interior noise using Taguchi method and a substructure synthesis method with a hybrid model. Firstly, the proposed method identifies the critical process of the concerned interior noise through a TPA (Transfer Path Analysis). Secondly, a strategy for a robust design is discussed, in which the major noise factor among uncertainties in the process is quality distribution of rubber bushes connecting a cradle and a trimmed body. Thirdly, a virtual test model fer the process is developed by applying a substructure synthesis method with a hybrid modeling approach. Fourthly, virtual tests are carried out according to the predefined tables of orthogonal array in Taguchi robust design process. The process was performed under 2 sub-steps. The first step is sensitivity analysis of 31 panels, and the other step is weight optimization of mass dampers on sensitive panels. Finally, two vehicles with the proposed countermeasures were validated. The proposed method reduces 87.5% of trials of measurements due to the orthogonal arrays and increases robustness by 8.6dB of S/N ratio and decreases $5\;dB(A){\sim}10\;dB(A)$ of interior noise in the concerned range of RPM.

• Advances in aircraft and spacecraft science
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• 제2권1호
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• pp.77-94
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• 2015

The paper focuses on the integration of a non-linear one-dimensional model of Synthetic Jet (SJ) actuator in a well-assessed numerical simulation method for turbulent compressible flows. The computational approach is intended to the implementation of a numerical tool suited for flow control simulations with affordable CPU resources. A strong compromise is sought between the use of boundary conditions or zero-dimensional models and the full simulation of the actuator cavity, in view of long-term simulation with multiple synthetic jet actuators. The model is integrated in a multi-domain numerical procedure where the controlled flow field is simulated by a standard CFD method for compressible RANS equations, while flow inside the actuator is reduced to a one-dimensional duct flow with a moving piston. The non-linear matching between the two systems, which ensures conservation of the mass, momentum and energy is explained. The numerical method is successfully tested against three typical test cases: the jet in quiescent air, the SJ in cross flow and the flow control on the NACA0015 airfoil.

• 한국멀티미디어학회논문지
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• 제25권6호
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• pp.844-851
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• 2022

This study intends to propose an evaluation tool for analyzing the sense of immersion of realistic VR game contents in the metabus game industry, which is rapidly increasing recently. This paper presents an analysis tool to measure the degree of immersion after selecting three types VR games for research, and analyzing the immersion way method of the game. The research method analyzes how the user and the sense of immersion formed in the storytelling in the game can have an effect. Based on the results, we present an sense of immersion analysis and measurement method for evaluating the usability of VR game contents, which is a key element in the metaverse era. Furthermore, it expands the immersion element that appears in storytelling to the game industry and seeks a new direction of development through connection with the VR game industry.

• 한국컴퓨터정보학회논문지
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• 제28권5호
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• pp.49-56
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• 2023

현재, 전자상거래는 디지털 트윈에서 메타버스 세상으로 변화되고 있다. 메타버스 세상은 가상 및 현실세계의 중간 형태로 코인 기반의 메타커머스(Meta-commerce)로 운영된다. 이러한, 메타커머스 세상은 아이템(콘텐츠)을 거래할 경우 블록체인 기반의 NFT 코인을 사용한다. 본 연구에서는 기존 단일형태의 NFT 발행이 아닌 대량 NFT 코인(인증)을 발행하는 방법에 관해 연구했다. 연구방법은 대량 NFT 색인 및 자동생성 방법으로 콘텐츠를 레이어(layer) 기반으로 제작하고 원하는 수량만큼 자동생성하도록 설계했다. 본 연구에서는 대량 민팅(minting)을 위해 NodeJS 기반의 프로그램으로 레이어 중첩 방법(배경, 본체, 기타)을 사용했다. 이렇게 만들어진 NFT 콘텐츠는 그룹 증명의 가치로 모임 및 그룹의 증명할 수 있는 블록체인 기반의 증명서로 활용할 수 있다. 또한, 제작된 콘텐츠 NFT 색인하고 NFT 마켓플레이스(Martplace) 사이트에 폴리곤 코인으로 NFT를 발행했다.

• 한국소음진동공학회논문집
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• 제22권1호
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• pp.29-37
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• 2012

This paper is concerned with the natural vibration characteristics of a rectangular plate with a rectangular hole in contact with the water. The addressed problem was solved by using the Rayleigh-Ritz method combined with the Green function method. This study presents the numerical approach, numerical results and experimental results. In addition, the validity of the approximate formula which mainly depends on the so-called non-dimensionalized added virtual mass incremental factor and the natural mode shape change due to the presence of the water were investigated. Experiments were also carried out to validate theoretical results. The theoretical results are in good agreement with the experimental results. It was found that the effect of a square hole on the natural frequencies of the square plate in contact with water is different from the effect of a square hole on the natural frequencies of the square plate in air and the approximate formula can predict lower natural frequencies in water with a good accuracy.

• Structural Engineering and Mechanics
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• 제12권1호
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• pp.101-118
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• 2001

The reliable prediction of elastic vibrations of wetted complex structures, as ships, tanks, offshore structures, propulsion components etc. represent a theoretical and numerical demanding task due to fluid-structure interaction. The paper presented is addressed to the vibration analysis by a combined FE-BE-procedure based on the added mass concept utilizing a direct boundary integral formulation of the potential fluid problem in interior and exterior domains. The discretization is realized by boundary element collocation method using conventional as well as infinite boundary element formulation with analytical integration scheme. Particular attention is devoted to modelling of interior problems with both several separate or communicating fluid domains as well as thin-walled structures wetted on both sides. To deal with this specific kind of interaction problems so-called "virtual" boundary elements in areas of cut outs are placed to satisfy the kinematical conditions in partial connected fluid domains existing in realistic tank systems. Numerical results of various theoretical and practical examples demonstrate the performance of the BE-methodology presented.

• 한국운동역학회지
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• 제27권2호
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• pp.149-155
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• 2017

Objective: The purpose of this study was to investigate the effects of three visual conditions (eyes opened, eyes closed, and wearing of a head mounted display [HMD]) on single-leg standing through kinematics and kinetic analysis. Method: Twelve college students (age: $24.5{\pm}2.6years$, height: $175.0{\pm}6.4cm$, weight: $69.2{\pm}5.1kg$) participated in this study. The study method adopted three-dimensional analysis with six cameras and ground reaction force measurement with one force plate. The analysis variables were coefficient of variation (CV) of the center of body mass, head movement, ground reaction force, and center of pressure, which were analyzed using one-way analysis of variance with repeated measures according to visual conditions. Results: In most cases, the results of this study showed that the CV was significantly higher in the order of HMD wearing, eyes closed, and eyes opened conditions. Conclusion: Our results indicated that body sway was the largest in the HMD wearing condition, and the risk of falling was high owing to the low stability.

• 대한건축학회논문집:계획계
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• 제36권4호
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• pp.103-111
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• 2020

Perforated metal sheets are used as panels of facades for controlling environmental factors while ensuring user's visibility. Despite their functional potentials, only a specific direction of facades or an orientation of a building was considered in the relevant studies. This study proposed a design methodology for the perforated panel facades that reflects the location on the facades and the user's requirements. The optimization of quantitative and qualitative performance is achieved through communication between designers and users in a VR system. In optimizing quantitative performances, designers use machine learning techniques such as clustering and genetic algorithm to allocate optimal panels on the facades. In optimizing qualitative performances, through the VR system, users intervene in evaluating performances whose preferences are depending on them. The experiment using the office project showed that designers were able to make decisions based on clustering using GMM to optimize multiple quantitative performances. The gap between the target and final performance could be narrowed by limiting the types of perforated panels considering mass customization. In assessing visibility as a qualitative performance, users were able to participate in the design process using the VR system.

• 한국정보통신학회논문지
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• 제18권12호
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• pp.3035-3041
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• 2014

3D 애니메이션 제작 과정에서 가상 카메라의 이동을 보다 자연스러운 영상으로 표현하기 위해서 스테디캠 기법을 많이 사용하고 있다. 가상카메라에서 스테디캠 효과를 표현하기 위한 기존의 방식은 키프레임을 이용하는 것으로 카메라의 모든 움직임을 수작업으로 처리한다. 그러나 영상에서 카메라 워킹을 수작업으로 처리하는 것은 제작 시간이 많이 소요되는 번거로운 작업이며 카메라의 움직임이라는 물리적 현상을 인위적으로 표현함으로써 부자연스러운 결과를 얻는다. 본 연구는 3D 애니메이션에서 가상카메라의 이동에 따라 카메라에 가해지는 물리적 현상을 모델링하여 자동으로 스테디캠 효과를 낼 수 있는 방식을 제안한다. 제안하는 물리적 모델링은 파이선 스크립트 언어로 구현되어 마야의 제작 플랫폼에서 바로 적용 가능하다. 제안하는 방법은 기존의 수기적인 제작환경을 개선하고 영상의 자연스러운 시각적 효과를 극대화 할 수 있다.

• 대한공간정보학회지
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• 제11권1호
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• pp.71-75
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• 2003

도로는 오랜 기간 동안 꾸준한 경제성장으로 경제적인 규모가 커짐에 따라 차량의 증가 및 대형화, 차량의 성능증대, 시간가치의 상승 및 교통의 고속화 등으로 교통상황이 크게 변화되었다. 최적 노선선정모델에 관한 연구는 컴퓨터와 지형공간정보의 발달로 인하여 1980년 후반부터 일부 연구가 이루어지고 있으며, 국내에서도 수치지형모델을 이용한 최적노선에 관한 연구를 비롯하여 토공량산정, 유토곡선출력, 자동화시스템구축등 많은 연구가 이루어지고 있다. 그리고 최근에는 컴퓨터의 발달로 VGIS(Virtual Geographic Information System)를 이용한 도로주행 시뮬레이션과 가상현실에 대한 연구가 이루어지고 있다. 본 연구는 노선설계에서 도로대안결정시 고려되는 주변시설 및 계발계획, 교통수요 예측등에 따른 검토 의견 외에 3차원시뮬레이션기법을 통한 경관분석과 환경영향분석요소의 추가가능성에 대하여 연구하였다.