• 한국자동차공학회논문집
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• 제14권1호
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• pp.129-137
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• 2006

This paper studies the effects of the swirl for the variation of intake port configuration that is key parameters in the flow field of direct injection diesel engines. In-cylinder flow characteristics is known to have significant effects on air-fuel mixing, combustion, and emissions. To investigate the effects of the swirl flow, various rpm(250, 500, 750) and two different intake port were used. And to evaluate the swirl motion in the flow field visualization engine, steady state flow test was conducted. Helical port intake port and SCV(Swirl Control Valve) were selected as the design parameters to increase the swirl flow and parametric study was performed. In the case of non-SCV, intake flow rate and non-dimensional swirl ratio were higher than those of SCV for the swirl head type. So, we could strengthen the swirl in the flow field with the swirl head type and don't using SCV. From the results of steady state flow test, non-swirl head type has the most good advantage for intake flow rate, and also the flow rate could be increased by using the SCV slightly. The effects of the type of engine head on intake air flow capability are dominant with respect to the existence of the SCV. We could measure the qualitative grade of swirl by capturing the scattering signal of microballoon from ICCD camera in the visualization diesel engine.

• Journal of Mechanical Science and Technology
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• 제14권4호
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• pp.456-465
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• 2000

An experiment was conducted to investigate the aerodynamic losses of high pressure steam turbine nozzle (526A) subjected to a large range of incident angles ($-34^{\circ}\;to\;26^{\circ}$) and exit Mach numbers (0.6 and 1.15). Measurements included downstream Pitot probe traverses, upstream total pressure, and end wall static pressures. Flow visualization techniques such as shadowgraph and color oil flow visualization were performed to complement the measured data. When the exit Mach number for nozzles increased from 0.9 to 1.1 the total pressure loss coefficient increased by a factor of 7 as compared to the total pressure losses measured at subsonic conditions ($M_2<0.9$). For the range of incidence tested, the effect of flow incidence on the total pressure losses is less pronounced. Based on the shadowgraphs taken during the experiment, it' s believed that the large increase in losses at transonic conditions is due to strong shock/ boundary layer interaction that may lead to flow separation on the blade suction surface.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.1036-1041
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• 2005

Treemaps, a space filling visualization technique, displays a massive data set of hierarchical data interactively on a single computer screen by mapping it to a matrix of rectangles. It allows users to visually inspect and manipulate data to find new relationships or discrepancies that are to difficult to find using traditional techniques. This paper applies treemaps to the evaluation of highway project bids, which contain hundreds or thousands of elements arranged in a hierarchical structure. Through a case study, treemaps are shown to be a potentially effective tool for bid evaluation by both contractors and State or Federal highway officials.

• 한국CDE학회논문집
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• 제13권3호
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• pp.209-216
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• 2008

This paper presents a novel approach to design evaluation of portable consumer electronic (PCE) products using augmented reality (AR) based tangible interaction and functional behavior simulation. In the approach, the realistic visualization is acquired by overlaying the rendered image of a PCE product on the real world environment in real-time using computer vision based augmented reality. For tangible user interaction in an AR environment, the user creates input events by touching specified regions of the product-type tangible object with the pointer-type tangible object. For functional behavior simulation, we adopt state transition methodology to capture the functional behavior of the product into a markup language-based information model, and build a finite state machine (FSM) to controls the transition between states of the product based on the information model. The FSM is combined with AR-based tangible objects whose operation in the AR environment facilitates the realistic visualization and functional simulation of the product, and thus realizes faster product design and development. Based on the proposed approach, a product design evaluation system has been developed and applied for the design evaluation of various PCE products with highly encouraging feedbacks from users.

• International Journal of Automotive Technology
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• 제5권1호
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• pp.9-16
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• 2004

An experimental study was carried out to characterize the spray atomization process of micro-machined port fuel injectors with a piezoelectric atomization device, which can generate pressure pulsations through vibration of a piezoelectric transducer. In this study, several types of micro-machined arrays such as 30∼200-microns of hole arrays were tested. Both a dual-stream and a central-port injectors with micro-machined arrays were tested and compared with normal port fuel injectors. The spray visualization was conducted to characterize overall spray structure and phase Doppler particle analyzer (PDPA) system was used to quantify the droplet size and velocity. In addition, the pressure history was recorded by using digitized signal from pressure transducer. The results showed that modulation is effective to the spray atomization for tested injectors and atomization performance depends on injector design factors, orifice sizes, and frequency and power of the modulator. A number of resonance frequencies of the modulator was modified by injector parameters and temperature. In addition, our results suggested that design of sufficient space among holes is critical to avoid droplet coalescence in the multi-hole micro-machined injectors.

• Structural Engineering and Mechanics
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• 제7권6호
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• pp.589-599
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• 1999

This paper presents the development and applications of the software package JIFEX, a new finite element system which can be used for structural analysis and optimum design by the modern computer hardware and software technologies such as MS Windows95/NT and Pentium PC platforms. The complete system of JIFEX is programmed with $C/C^{++}$ language to make full use of advanced facilities of MS Windows95/NT. In the system, the finite element data pre-processing, based on the most popular CAD package AutoCAD (R13, R14), has been implemented, so that the finite element modeling could be integrated with geometric modeling of CAD. The system not only has interactive graphics facility for data post-processing, but also realizes the real-time computing visualization by means of the Dynamic Data Exchange (DDE) technique. Running on the Pentium computers, JIFEX can solve large-scale finite element analysis problems such as the ones with more than 60000 nodes in the finite element model.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.439-445
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• 2021

In view of the complex geometric structure of the rod bundle channel and the limitation of the current CHF visualization experiment technology, it is very difficult to obtain the rod bundle CHF mechanism directly through the phenomenon of the rod bundle CHF visualization experiment. In order to obtain the applicable CHF mechanism assumption for rod bundle channel, firstly, five most representative DNB type round tube CHF mechanistic models are obtained with evaluation and screening. Then these original round tube CHF mechanistic models based on inlet conditions are converted to local conditions and coupled with subchannel analysis code ATHAS. Based on 5 × 5 full-length rod bundle CHF experimental data independently developed by Nuclear Power Institute of China (NPIC), the applicability research of each model for CHF prediction performance in rod bundle channel is carried out, and the commonness and difference of each model are comparatively studied. The CHF mechanism assumption of superheated liquid layer depletion that is most likely to be applicable for the rod bundle channel is selected and two directions that need to be improved are given. This study provides a reference for the development of CHF mechanistic model in rod bundle channel.

• 한국가시화정보학회지
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• 제10권3호
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• pp.30-36
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• 2012

We are planning to construct a scaled-down moderator facility to simulate the CANDU-6 moderator circulation phenomena during steady state operating and accident conditions. In the present work a preliminary experiment using a 1/40 scaled-down moderator tank has been performed to investigate the anticipated problems of the flow visualization and measurement in the planning scaled-down moderator facility. We shortly describe CFD analysis result for the 1/40 scaled-down test model and the flow measurement techniques used for this test facility under isothermal flow conditions. The Particle Image Velocimetry (PIV) method is used to visualize and measure the velocity field of water in a transparent Plexiglas tank. Planar Laser Induced Fluorescence (PLIF) technique is used to evaluate the feasibility of temperature field measurement in the range of $20-40^{\circ}C$ of water temperature using an one-color method.

• 한국컴퓨터정보학회논문지
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• 제15권12호
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• pp.181-188
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• 2010

본 논문은 수집된 항공기의 상황 자료를 이용하여 웹 기반의 구글 어스와 OpenGL을 이용한 3차원 시각화을 통하여 항공기의 올바른 상황인식과 상태정보를 지원하는 시스템을 제안한다. 기존에 제안된 시스템은 방대한 지형 자료와 지도 및 위성사진을 연동하여 표현함으로 속도 저하 및 한정된 지도 정보만을 가시화하는 문제점을 가진다. 제안하는 시스템은 개방된 구글 어스의 Open API을 이용하여 최소한의 비행 정보만으로 실시간 상황인식을 위한 경제적이고 전역적인 시각화 도구를 지원한다. 또한 사용자의시각적 편리성을 위하여 다중 위치 정보를 볼 수 있는 확장 뷰를 제공한다. 본 연구결과는 웹 환경에서 항공기의 상황인식을 지원하는 시스템으로 이용될 수 있는 가능성을 보인다.

• 한국컴퓨터정보학회논문지
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• 제27권4호
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• pp.37-43
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• 2022

본 논문에서는 2019년 12월부터 2020년 7월까지 약 8개월간 유통되었던 코로나19와 관련된 뉴스데이터를 이용하여 일자 및 지역별로 단어에 대한 빈도를 구하고, 결과를 활용하여 코로나19 환자에 대한 현황 데이터와의 상관관계를 시각화하였다. 뉴스데이터는 한국언론진흥재단에서 운영하고 있는 뉴스 빅데이터 시스템 '빅카인즈'에서 수집된 데이터를 활용하였다. 본 논문에서 제안하는 시각화 시스템은 지역과 기간을 선택하면 분석한 결과를 이용하여 전체 지역 대비 선택한 지역의 뉴스 빈도수, 선택한 지역의 주요 키워드, 주요 키워드의 지역별, 일자별 변화 등을 보여 주고 있다. 이러한 시각화를 통하여 이전에 발생하였던 사건에 대해 주요 키워드와 코로나19 확진자 및 감염자 추이를 확인할 수 있다.