• Journal of the KSME
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• v.34 no.4
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• pp.225-238
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• 1994

엔진의 연소에 중요한 영향을 미치는 가스 유동장의 해석을 위하여 현재 주로 사용되고있는 광 응용 계측기술에 대하여 소개하였다. 소개한 예에서 알 수 있는 바와 같이 점계측을 기초로 하는 정량계측만으로는 유동장전체를 파악하기엔 부족한 감이 있으며, 정성적일 뿐만 아니라 또한 정량적인 해석까지도 가능하게 하는 가시화수법을 추구하게 되는 일련의 움직임이 보여지고 있다. 여기서 소개한 예 이외에도 엔진 내의 유동장해석에는 많은 다른 방법들이 적용되고 있 으며, 지금 이 순간에도 보다 더 차원성이 높고 시간과 공간분해능이 우수한 새로운 광응용 계 측기술들이 개발 중에 있다고 하겠다. 이와 같은 광응용 계측기술의 진보야말로 차세대 엔진개 발을 위한 중요한 역할을 담당하게 되리라는 확신과 기대를 가져도 좋으리라 여겨진다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.404-407
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• 2011

The fluidic thrust vector control using co-flowing coanda effect of secondary jet at the nozzle exit is a new concept for efficient thrust vectoring of supersonic jet exhausts. Flow visualization of the flow fields in previous studies have shown some pros and cons of the technique, however, most of the observations were somewhat limited as qualitative data. The present study was designed to evaluate the quantitative performance-characteristics of the thrust-vectoring technique utilizing coanda effects of the secondary jet. Details of design of the test device and calibration/data reduction procedure are provided.

• Composites Research
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• v.12 no.2
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• pp.70-81
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• 1999

Resin transfer molding(RTM) as a composite manufacturing process is currently of great interest in the aerospace industry requiring high performance composite parts. In this study, an analysis of mold filling in the RTM process was carried out by numerical simulation using finite element/control volume technique. Experimental work for the visualization of resin flow through fibrous preform was also conducted in order to quantitatively measure the permeabilities of the fiber mats and to evaluate the validity of the developed numerical code. The different types of fiber mats and silicon oils were selected as reinforcements and resin materials, respectively. The effects of fibrous preform structure, mold geometry, and preplaced insert on the flow front patterns during mold filling were examined by integrating the model predictions and experimental results. The flow fronts predicted by numerical simulation were in good agreement with those observed experimentally. However, according to the regions of the mold, some deviations between predicted and observed flow fronts could be found because of non-uniform fiber volume fraction. Weldline locations for the resin flow through round insert preplaced in the mold could be qualitatively deduced based on predicted flow fronts.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.604-605
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• 2017

The present work aims at visualization of the supersonic air jet flows discharged from C-D nozzles. In the present experiments, Prticle Image Velocimetry (PIV) was employed to specify the jet flow field quantitatively, and a color Schlieren optical method was applied to observe the same jets qualitatively. The $0.5{\mu}s$ duration of spark light source was used for Schlieren and it can be controled as $0.5{\mu}s$, $1{\mu}s$, $2{\mu}s$ and focusing mode. The convergent-divergent nozzles were used to generate the jet flow with the design Mach number of 2.0, 2.2. Nozzle pressure ratios (NPRs) were varied from 5 to 8. A good comparison of the jet size and shock location from the Schlieren images with the PIV quantitative values is obtained. The obtained images clearly showed the major features of the under-expanded jet, over-expanded jet, sound wave, turbulent eddies and so on.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.1
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• pp.3-11
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• 2011

This paper aims to develop a web based GIS system which is able to evaluate and visualize the overall degree (in terms of pleasantness and aesthetics) of pedestrian friendliness of the environment, as well as pedestrians' convenience through a Walkability Indicators that simplify pedestrian environment elements into a quantitative index in accordance with characteristics of pedestrian space. To make this goal come true, we developed and applied Walkability index which can measure the pedestrian environment through reflecting quantitative Indicators based on GIS supplementing the limit of Literature Review. In addition, in order to develop index we utilized AHP(Analytic Hierarchy Process) and we displayed measurement result on study area through web GIS Services. The proposed pedestrian measurement system is expected to be applicable in the visualization of pedestrian movements and the evaluation of convenience levels of pedestrian environment.

• Korean Journal of Remote Sensing
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• v.34 no.2_2
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• pp.407-418
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• 2018

The frequency and risk of disasters are increasing due to environmental and social factors. In order to respond effectively to disasters that occur unexpectedly, it is very important to quickly obtain up-to-date information about target area. It is possible to intuitively judge the situation about the area through the image-map generated at high speed, so that it can cope with disaster quickly and effectively. In this study, we propose an image-map generation and visualization system from UAV images for real-time disaster monitoring. The proposed system consists of aerial segment and ground segment. In the aerial segment, the UAV system acquires the sensory data from digital camera and GPS/IMU sensor. Communication module transmits it to the ground server in real time. In the ground segment, the transmitted sensor data are processed to generate image-maps and the image-maps are visualized on the geo-portal. We conducted experiment to check the accuracy of the image-map using the system. Check points were obtained through ground survey in the data acquisition area. When calculating the difference between adjacent image maps, the relative accuracy was 1.58 m. We confirmed the absolute accuracy of the image map for the position measured from the individual image map. It is confirmed that the map is matched to the existing map with an absolute accuracy of 0.75 m. We confirmed the processing time of each step until the visualization of the image-map. When the image-map was generated with GSD 10 cm, it took 1.67 seconds to visualize. It is expected that the proposed system can be applied to real - time monitoring for disaster response.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.549-554
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• 1996

원전의 안전성을 보다 확보하기 위해서는 혁신적인 안전개념 도입과 체계적인 안전성 평가 및 성능검증의 강화가 수반되어야 한다. 본 논문에서는 신형 원전에 적용될 안전규제기술요건의 체계와 세부사항으로서 인간공학설계에 관련된 일반안전요건, 상세기술요건, 규제지침에 포함될 주요 내용의 기본사항을 제안하였고, 인간공학설계와 관련된 규제요건의 계층적 구조 방안을 정량화하고 가시화하기 위한 연구·개발될 내용과 방향을 제시하였다. 또한 제시된 요건에 관한 주요 기본사항들은 구체화하기 위한 다각적인 검증평가 과정과 추가 연구가 수행될 예정이다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.2
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• pp.217-224
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• 2002

It is very important to measure and visualize the changes in the physical properties of fluid flow because this is the foundation of measurement techniques used in aerodynamics, heat transfer, plasma diagnostics, and stress analysis of transparent models. The optical methods are advantageous over probe-based techniques in the optical methods are of high speed, non-contact and are capable of providing full-field results with high spatial resolution. Therefore we propose the electronic speckle pattern interferometry(ESPI) that gives us a solution to overcome those limitations. In this paper the experimental results show qualitative and quantitative visualization of changes in the physical properties of the candle and alcohol lamp with 3D plotting. And we obtained the refractive index, mass density and temperature distribution of fluids. The results clearly show the process of flow phenomena and give the feasibility of quantitative interpretation of gasdynamics.

• 한국가시화정보학회:학술대회논문집
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• 2005.12a
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• pp.58-63
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• 2005

Three-dimensional vortical structures in the wake behind a road vehicle has been visualized with the help of two-dimensional PIV measurement data. A three-dimensional velocity field has been reconstructed from several sectional measurement data in the x-y, y-z and z-x planes. Isovorticity surface observed by stacking only the sectional data in each plane, does not show the vortical structures within the recirculation region but represents only the strong shear flows. Thus, in the present study, the velocity component normal to the x-y plane is obtained by interpolating those velocities in the z-x plane. Then, a $\lambda_{2}$-definition which captures the local pressure minimum or vortex core, is applied to visualize the vortices in the recirculation region. The final results represent a successful configuration for the three-dimensional vortices.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.346-348
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• 2003

레디언스 엔진(Radiance Engine)은 미국 Lawrence Berkeley Laboratory(LBL)에서 개발된 빛의 거동을 물리적으로 시뮬레이션한 결과로부터 조도 및 휘도 분포를 계산하고 가시화 하여 빛 환경의 정량적, 정성적 평가가 모두 가능한 전 세계적으로 수많은 사용자 그룹이 형성되어 있는 프로그램이다. 그러나 많은 사용자 층을 보유하고 있음에도 불구하고 텍스트 기반의 인터페이스와 UNIX 환경의 워크스테이션급 컴퓨터에서만 실행되는 한계를 가지고 있기 때문에 그래픽 기반의 인터페이스에 익숙해져 있는 사용자들이 이용하기 어렵고. 비용적으로 고성능 컴퓨터에 대한 많은 부담이 있어 대중화가 되고 있지 못하는 실정이다. 본 논문에서는 아직까지 그 우수성에도 불구하고 불편한 인터페이스와 고성능의 서버를 필요로 하는 이유로 국내에서 활발하게 사용되고 있지 못하는 레디언스 엔진을 다수의 사용자가 쉽고 빠르며 간편하게 이용 할 수 있도록 각각의 사용자자가 제출한 레디언스 엔진 수행 작업을 분산하여 처리할 수 있는 클러스터링 시스템을 설계하고 구현한다.