• 대한기계학회논문집B
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• 제28권3호
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• pp.365-370
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• 2004

Simultaneous measurement with PLIF(Planar Laser-Induced Fluorescence) and Stereo-PIV(Stereo Particle Image Velocimetry) was performed to investigate the structural characteristics of flow field in Rushton Turbine Mixer. Instantaneous 3D velocity fields are measured by two 2K${\times}$2K CCD cameras focused on an object plane with the angular displacement methods while the concentration fields are obtained through the measurement of the fluorescence intensity of Rhodamine B tracer excited by the second pulse of Nd:Yag laser light. Image distortion due to the camera view-angle is compensated by a mapping function. Finally, the spatial structures of turbulent flow around Rushton turbine were identified by the calculation of synchronized data of the velocity field and concentration field.

• 대한기계학회논문집B
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• 제22권5호
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• pp.708-715
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• 1998

The shelter effect of a porous wind fence on a triangular prism was experimentally investigated in a circulating water channel. A porous fence of porosity .epsilon.=38.5% was installed in front of the prism model. The fence and prism model were embedded in a turbulent boundary layer. The instantaneous velocity fields around the fence and prism model were measured by using the instantaneous velocity fields around the fence and prism model were measured by using the 2-frame PTV(Particle Tracking Velocimetry) system. By installing the fence in front of the prism, the recirculation flow region decreases compared with that of no fence case. The porous fence also decreases the mean velocity, turbulent intensity and turbulent kinetic energy around the prism. Especially, at the top of the prism, the turbulent kinetic energy is about half of that without the fence.

• 대한기계학회논문집B
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• 제27권4호
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• pp.504-510
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• 2003

Simultaneous measurements of turbulent velocity and concentration field in a stirred mixer tank are carried out by using PIV/LIF technique. Instantaneous velocity fields are measured with a 1K$\times$1K CCD camera adopting the frame straddle method while the concentration fields are obtained by measuring the fluorescence intensity of Rhodamine B tracer excited by the second pulse of Nd:Yag laser light. Image distortion due to the camera view-angle is compensated by a mapping function. It is found that the general features of the mixing pattern are quite dependent on the local flow characteristics during the rapid decay of mean concentration. However, the small scale mixing seems to be independent on the local turbulent velocity fluctuation.

• 대한한의학회지
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• 제31권5호
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• pp.60-63
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• 2010

Objectives: The purpose was to take a closer look at the fundamental principles of Intense Pulsed Light (IPL) and to investigate its clinical applications for Korean medical fields. Results: IPL is a type of light treatment that is employed by radiating the short-pulse wave, which is transformed from high-intensity light. It may be used to stimulate skin along meridian channels in clinical fields of Korean medicine like acupuncture, moxibustion, cupping therapy, Guasha therapy, and other related traditional techniques. So, it may be feasible to treat not only lentigines, freckles, facial dermatitis, and acne, but also other applications. In addition, it could be recommended for use with herb remedies or herb facial mask packs. Conclusions: IPL may be a plausible method in phototherapy of Korean medicine.

• 한국광학회지
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• 제2권1호
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• pp.1-6
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• 1991

회절현상을 이용하여 복수 미세 입자의 특성 측정을 위한 격자형의 검지기를 사용한 데이터 처리방식을 제안하고 이에 따른 광학 및 신호처리 시스템을 구성하였다. 에너지 분포함수의 최대치와 최소치를 이용하여 같은 분무기로 분무된 증류수, 알코올, 실리콘 오일, 글리세린 등의 분포를 측정했는데 최대치와 최소치에 의해 구한 입자의 크기가 서로 잘 일치하였다.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2002년도 추계학술대회 논문집
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• pp.101-104
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• 2002

Simultaneous measurement of turbulent velocity and concentration field in a stirred mixer tank is carried out by using PIV/LIF technique. Instantaneous velocity fields are measured by a $1K\times1K$ CCD camera adopting the frame straddle method while the concentration fields are obtained by measuring the fluorescence intensity of Rhodamine B tracer excited by the second pulse of Nd:Yag laser light. Image distortion due to the camera view-angle is compensated by a mapping function. It is found that the general features of the mixing pattern are quite dependent on the local flow characteristics during the rapid decay of mean concentration. However, the small scale mixing seems to be independent on the local turbulent velocity fluctuation.

• Structural Engineering and Mechanics
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• 제82권2호
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• pp.259-270
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• 2022

The paper investigates the residual stresses arising in a thermoviscoelastic cylinder as a result of layer-by-layer deposition of material on its lateral surface. Internal stresses are caused by incompatible deformations that accumulate in the assembly as a result of joining parts with different temperatures. For the analysis of internal stresses, an analytical solution to the axisymmetric quasi-static problem of thermoelasticity for a growing cylinder is constructed. It is shown that the distribution of residual stresses depends on the scenario of the surfacing process. In this case, the supply of additional heat to the growing body can significantly reduce the unevenness of temperature fields and reduce the intensity of residual stresses. The most effective is uneven heating, which can be realized, by the action of an alternating current with a tunable excitation frequency. The temperature and residual stresses fields on the growing surface is analyzed numerically for Titanium and Copper materials.

• Wind and Structures
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• 제18권5호
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• pp.473-495
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• 2014

Localized wind events, in the form of tornadoes and downbursts, are the main cause of the large number of failure incidents of electrical transmission line structures worldwide. In this study, a numerical model has been developed to study the behaviour of self-supported transmission lines under various tornado events. The tornado wind fields used were based on a full three-dimensional computational fluid dynamics analysis that was developed in an earlier study. A three-dimensional finite element model of an existing self-supported transmission line was developed. The tornado velocity wind fields were then used to predict the forces applied to the modelled transmission line system. A comprehensive parametric study was performed in order to assess the effects of the location of the tornado relative to the transmission line under F2 and F4 tornado wind fields. The study was used to identify critical tornado configurations which can be used when designing transmission line systems. The results were used to assess the sensitivity of the members' axial forces to changes in the location of the tornado relative to the transmission line. The results were then used to explain the behaviour of the transmission line when subjected to the identified critical tornado configurations.

• 한국결정성장학회지
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• 제4권3호
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• pp.210-222
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• 1994

축방향의 균일한 자장이 Czochralski 도가니에 가하여졌을 때의 유동장, 온도장 및 산소의 농도장이 수치적으로 연구되었다.Czochralski 유동장과 농도장에 작용하는 부력, thermocapillarity, 원심력, 자성력, 산소의 확산계수, 산소의 segregation coefficient, SiO형태의 evaporation, 도가니벽의 ablation 등이 고려되었다. 회전방향으로의 대칭성으로부터 자오면에서의 속도성분과 회전방향의 속도성분, 온도, 전류의 흐름 등이 먼저 정상상태에 도달하였다고 가정하고 초기에 일정한 산소의 농도가 주어진 상황에서 비정상 상태의 산소의 농도장이 해석되었다. Czochralski 유동장에서의 대류와 확산에 의한 산소의 전달현상이 파악되었으며 결정성장 표면으로 흡수되는 산소의 농도가 연구되었다.

• Journal of Mechanical Science and Technology
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• 제15권7호
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• pp.895-905
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• 2001

This paper presents vector fields, three dimensional mean velocities, turbulent intensities, turbulent kinetic energy and Reynolds shear stresses measured in the X-Y plane of the gas swirl burner with a cone type baffle plate by using an X-type hot-wire probe. This experiment is carried out at the flow rates of 350 and 450ℓ/min which are equivalent to the combustion air flow rate necessary to release 15,000 kcal/hr in a gas furnace. The results show that the maximum axial mean velocity component exists around the narrow slits situated radially on the edge of a burner. Therefore, there is some entrainment of ambient air in the outer region of a burner. The maximum values of turbulent intensities occur around the narrow slits and in front of a burner up to X/R=1.5. Moreover, the turbulent intensity components show a relatively large value in the inner region due to the flow diffusion and mixing processes between the inclined baffle plate and the swirl vane. Consequently, the combustion reaction is expected to occur actively near these regions.