In thermal cutting process, gas flow injected from the nozzle has a significant effect on the cutting materials. The gas flow is difficult to observe gases are transparent, therefore, in this study, Schlieren method was adopted to visualize the gas flow inside the kerf. The kerf shape was inserted between two slices of transparent glass in order to imitate the real cutting environment. In order to get the flow characteristics, a high speed camera was equipped and the image processing was applied to compare the before and after injection images. As a result, the method for visualizing gas flow was successfully developed and also expected to be applied to the analysis of purging gas in various welding environments.

플로우 데이터는 지역간 공간적 상호작용이나 상호작용에 따른 공간 조직의 형성과 변화 등을 분석하고 이해하는데 중요한 자료로 활용되고 있다. 플로우 데이터에 대한 전통적인 지도학적 시각화 방법으로 널리 사용되고 있는 유선도는 복잡하고 많은 유선의 표현에 따른 낮은 가독성이나 중첩성 등이 한계로 지적되고 있다. 이에 본 연구는 최근 비공간적 데이터 뿐 아니라 공간 데이터의 새로운 재현 방법으로 각광받고 있는 정보 시각화 도구에 주목하여, 플로우 데이터의 지리적 시각화 기법으로서 정보 시각화 도구의 적용가능성을 탐색하고 각 기법에 대한 유용성을 체계적으로 평가하고자 한다. 이를 위해 자바스크립트 기반의 데이터 시각화 라이브러리인 D3.js의 강제 유향 그래프, 코드 다이어그램, 위계적 엣지 번들링, 생키 다이어그램, 시간 거리 그래프를 활용하였으며, 실제 고속 철도 운행 플로우에 대한 다양한 시각화 사례를 실제로 개발하여 보여주고 있다. 사례 분석 결과, 각 정보 시각화 기법은 전통적인 유선도가 갖는 한계들을 효과적으로 극복할 수 있으며, 플로우 데이터에 대한 대안적인 시각화 기법으로 유용하다는 것을 확인할 수 있었다. 또한 이를 통해 본 연구는 플로우 데이터의 지리적 시각화 분야에 유용한 가이드라인을 제공할 수 있고, 지리학, 지도학 및 공간 정보 분야에서 공간 정보의 매핑과 시각화 방법에 대한 인식적 변화를 가져올 것으로 기대한다.

This study is aimed to design the mechanical gascyclone precipitator with an outstanding collection efficiency as one of ways to reduce exhaust gas of small-scale vessels. It estimated fine particles generated from diesel engines which has become one of the biggest environmental issues currently. Specifically, it quantitatively analyzed the flowing process from the cyclone gas exit; a duct via part to the collecting part of Cylindrical lower using DPIV (Digital Particle Image Velocimetry). Since the gas inlet height part became wider the previous theoretical dimensions, internal fluid characteristics of cyclone where the speed of internal swirl had been slow were investigated by temporary streamline of fine particles at 14-20 ㎛. The results showed that collecting efficiency was three times higher than the conical type utilized previously. In addition, this study supplemented imprecision problems from the previous theoretical equation and CFD interpretation with an experimental method. It also provided a basic data to design the cyclone precipitator by size of diesel engines for vessels.

Computational fluid dynamic (CFD) could analysis the flow characteristics in the nozzle exit with fluid condition variation. Consequently, the purpose of this paper is to show that the fluid temperature and velocity field formed in the nozzle exit dominates the understanding for flow phenomenon. High fluid velocity can cause such a high temperature in the test gas that dust the particles grow. For this reason the flow conditions with air-air, air-vapor as test gases were used in this paper. The most important result to come from the CFD was the existence of the shock wave structure which was a dominant influence on the flow characteristics in the nozzle exit. Specially, It has an advantage to confirm the normal shock wave location because the temperature field variation of the flow distinguish clearly through mach disc.Also, the temperature through normal shockwave is at around 2.0 times higher than in atmosphere fluid condition. Consequently, this can be used as a good technical background for the design of rocket engine.

In physical engineering, the turbulent flow on the surface roughness is very important. The roughness of the surface changed the distance of the interval. The roughness coefficient occurred with increasing turbulence intensities was stronger. The turbulence intensity away from the roughness in the shape was zero. The variation of turbulence intensity at the experimental flow conditions change was not affected.

It is intended to develop an experimental apparatus which can visualize flow patterns in condensate water reuse system with various cross sections. PVC particles on fluid surface help to obtain clear flow images. The flow region that were found in the experiments are steady, unsteady and significantly-mixed flows.

선박의 연돌에서 배출되는 배기가스는 해상조건과 선박에 미치는 풍속 등 외부 환경조건이나 항행속도에 따라 배기의 확산조건이 달라지며 구조물의 형상에 따라 역류하는 경우도 발생되게 된다. 이 연구에서는 실선을 1:400로 축소한 모델을 사용하여 거주구 주위의 유동특 성을 PIV기법을 통하여 계측하였다.

This study presents the method of design and manufacturing of aspheric lens for flow visualization. Spherical lens is used in many fields especially flow visualization experiment. Because sperical lens has aberration by origin in flow visualization, there is case that is alternated by asperic lens. Most of asperic lens's modeling which is applied to Taylor's method. This study is designed to the aspheric lens by Euler's method, which is useful method for various geometric shape and complex experimental apparatus for flow visualization. In the present study, we have verified design and manufacturing aspheric lens through a flow visualization experiment.