• 대한기계학회논문집B
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• 제21권8호
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• pp.1024-1033
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• 1997

The past several years have witnessed an ever-increasing acceptance and adoption of parallel processing, both for high performance scientific computing as well as for more general purpose applications. Furthermore with increasing needs to perform the complex flow calculations in an efficient manner, the use of the message passing model on distributed networks has emerged as an important alternative to the expensive supercomputers. This work attempts to provide a generic framework to enable the parallelization of all CFD-related works using the master-slave model. This framework consists of (1) input geometry, (2) domain decomposition, (3) grid generation, (4) flow computations, (5) flow visualization, and (6) output display as the sequential components, but performs computations for (2) to (5) in parallel on the workstation clustering. The flow computations are parallized by having multiple copies of the flow-code to solve a PDE on different spatial regions on different processors, while their flow data are exchanged across the region boundaries, and the solution is time-stepped. The Parallel Virtual Machine (PVM) is used for distributed communication in this work.

• 한국가시화정보학회지
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• 제15권2호
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• pp.59-67
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• 2017

To verify floatability of ABB (Air bubble barrier), we compared bubble swarm behavior with and without the air-driven ejector. Experiment was conducted using the fabricated air-driven ejector with 5 mm nozzle on the bottom of 1 m3 water tank. Reynolds number of air in the nozzle was ranged 1766-13248. We analyzed data with statistical method using image processing, particle mage velocimetry (PIV) and proper orthogonal decomposition (POD) analysis. As a result of POD analysis, there was no significant eigenmode in bubbly flow generated from the ejector. It means that more complex turbulent flows were formed by the ejector, thereby (1) making bubbles finer, (2) promoting three-dimensional energy transfer between bubble and water, and (3) making evenly distributed velocity profile of water. It is concluded that the air-driven ejector could enhance the performance of ABB.

• 한국가시화정보학회지
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• 제10권2호
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• pp.20-24
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• 2012

Increasing the active catalyst surface area is important in improving a converter's efficiency. In addition, uniform flow is advantageous in that it produces more efficient catalytic conversion. This results in the ability to use a smaller catalytic converter with uniform flow as opposed to a larger converter requirement for non-uniform flow. Therefore, it is important to characterize the internal flow of the catalytic converter. To characterize the system's flow patterns, velocity measurements were taken at the mid and exit planes of a ceramic honeycomb catalytic converter at flow rates of 37.8 l/s and 94.4 l/s. Measurements were conducted using LDV. The profiles were measured along both the major and minor axis of the planes. Primary flow direction velocities measured along the minor axis, at both flow rates, varied greatly at the mid plane and somewhat at the exit plane. The areas of greatest air flow were seen near the edges of the walls and on the side of the converter opposite the flow's entrance region. It also appears that the high velocities opposite the intake are due to the design of the entrance region. The entrance region is possibly too small to properly redirect the vertically entering fluid into an evenly distributed flow in the primary flow direction.

• 한국기계가공학회지
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• 제19권1호
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• pp.56-62
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• 2020

The purpose of this study is to observe the visualization of the flow field for air flow distributed in the car from the ventilation fan installed in the ceiling of the passenger elevator car through the numerical analysis using computational fluid dynamics. STAR-CCM+, which is a code used for the numerical analysis, was used to predict the airflow distribution inside the elevator car. The numerical analysis of the distribution of the air current in the elevator was carried out. As a result, the analysis results for each point and the visualization of the air current distribution and the temperature distribution in the elevator car and were obtained. It was found that heat transfer was actively occurring inside the car due to the influence of the flow field discharged from the ventilation vent installed in the ceiling in the elevator car, and especially the convection heat transfer of Model-2 was more active than that of Model-1. As a result, the temperature distribution inside the car was found to be relatively low. In addition, the temperature distribution at a cross-section of 1700mm height in the elevator car shows that Model-2 is the location of the ventilation vent which makes people feel more comfortable.

• 정보처리학회논문지B
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• 제12B권5호
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• pp.535-542
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• 2005

증강 협업 환경은 지리적으로 떨어진 그룹과 그룹간의 사용자들이 함께 어려운 문제를 풀 수 있도록 도와주는 다수의 디스플레이를 활용하는 작업 환경이다. 본 논문은 실시간 협력 작업 환경의 특징적인 공유 작업 공간 모델을 살펴본다 그리고 과학적 가시화를 위한 증강 협업 환경의 공유 작업 공간 모델을 검증하는 반복적인 디자인 실험연구를 설명하고 있다 이 연구에서 원거리 사용자들의 협업을 향상시키기 위한 증강 협업 환경의 디스플레이 기술 설정을 바꿔가며 사용자 평가 실험이 진행되었다. 각 실험에서 두 개의 방에 두 명씩 분산된 그룹들에게 협업 가시화를 이용한 집중적인 분석 작업을 시켰다. 그 결과 다른 사람들의 작업 내용을 쉽게 볼 수 있는 고화질 작업환경의 항시 가시성이 분산된 구성원들 간의 상호 인지도와 협력에 도움이 되어 협업 능률을 향상시켰다.

• 한국가시화정보학회지
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• 제9권2호
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• pp.34-39
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• 2011

This paper presents a novel direct fabrication method of the thin metal film RTD temperature sensor array on an arbitrary curved surface by using MEMS technology to measure a distributed temperature field up to $300^{\circ}C$ without disturbing a fluid flow. In order to overcome the difficulty in the three dimensional photography of sensor patterning, the UV pre-irradiated photosensitive dry film resist technology has been developed newly. This method was applied to the fabrication of the temperature sensor array on a glass tube, which is arranged parallel and transverse to a main flow. Gold was used as a temperature sensing material. The resistance change was measured in a thermally controlled oven by increasing the environmental temperature. The linear increase in resistance change and a constant slope were obtained. Also, the sensitivity of each RTD temperature sensor was evaluated.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1614-1622
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• 2018

The research related to fault diagnosis in permanent magnet synchronous motors (PMSMs) has attracted considerable attention in recent years because various faults such as permanent magnet demagnetization and short-circuited turns can occur and result in unexpected failure of motor related system. Several conventional current and back electromotive force (BEMF) analysis techniques were proposed to detect certain faults in PMSMs; however, they generally deal with a single fault only. On the contrary, cases of multiple faults are common in PMSMs. We propose a fault diagnosis method for PMSMs with single and multiple combined faults. Our method uses three phase BEMF voltages based on the fast Fourier transform (FFT), support vector machine(SVM), and visualization tools for identifying fault types and severities in PMSMs. Principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE) are used to visualize the high-dimensional data into two-dimensional space. Experimental results show good visualization performance and high classification accuracy to identify fault types and severities for single and multiple faults in PMSMs.

• 한국가시화정보학회지
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• 제19권1호
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• pp.18-27
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• 2021

As the photo-voltaic (PV) industry grows, the floating PV has been suggested to resolve current environmental destruction and a lack of installation area. Currently, various floating PV systems have been developed, but there is a lack of studies on how the shape of the floating body and other compositions are affecting structural behavior. In this study, the behavior of the floating PV was investigated at the various length of mooring lines, stiffness of connecting hinges, and size of floating bodies. The shortest mooring lines with the distributed type floating PV showed the least force on the floating body and corresponding motion. A frictionless hinge is safer at the regular and low-height wave, while a stiff hinge is safer at irregular and high-height wave. In addition, due to the bi-axial distribution of the connecting hinge, 45° direction wave was found to be the most dangerous.

• 한국군사과학기술학회지
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• 제27권1호
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• pp.60-69
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• 2024

The importance of geospatial information is increasingly highlighted in the defense domain. Accurate and up-to-date geospatial data is essential for situational awareness, target analysis, and mission planning in millitary operations. The use of high-resolution geospatial data in military operations requires large storage and fast image processing capabilities. Efficient image processing is required for tasks such as extracting useful information from satellite images and creating 3D terrain for mission planning, In this paper, we designed a cloud-based operational situation mixed reality visualization system that utilizes large-scale geospatial information distributed processed on a cloud server based on the container orchestration platform Kubernetes. We implemented a prototype and confirmed the suitability of the design.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제2권12호
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• pp.849-854
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• 2013

본 논문에서는 공간 데이터를 기반으로 한 도시의 다양한 통계 정보를 제안된 알고리즘을 통해서 시각화하고 시각화된 데이터를 지도와 사상(Mapping)하여 분석할 수 있게 할 뿐만 아니라 공간적 정보를 기반으로 의사 결정을 하는 경우 활용할 수 있는 문서를 사용자의 간단한 조작으로 프로그래밍 방식에 의해 작성해주는 시스템을 제안한다. 제안된 기법은 2차원 지도 데이터에서 특징데이터 값에 대해 색을 이용하여 표현하는 기법인 히트 맵 분석 (Heat Map Analysis)기법과 공간적 근접성을 정의할 때 이용되는 버퍼링 분석 (Buffering Analysis) 기법을 활용한다. 본 시스템을 통해서 공간적 정보를 시각화를 한다면 지역의 분포된 다양한 공간적 정보를 쉽게 파악할 수 있을 것이다. 또한 분석된 정보를 기반으로 제공되고 있는 문서 자동생성기능을 활용한다면 표현된 공간적 정보의 문서화에 필요한 많은 시간과 비용을 절감할 수 있을 것으로 기대된다.