• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2324-2330
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• 2010

In middle and high school to learn the principles of fluid mechanics to Experiments in space and time constraints and difficulties for the study of the principles of fluid mechanics to the problem is superficial. In this paper, Pascal's principles, Archimedes' Principle, Bernoulli's Theorem, etc. learning about the fluid mechanics and implemented in Web Browser, In connection with flash and HTML, web simulation is to implement. Web Based Instruction program that implemented a comparative analysis became an effect of 15% to industrial total high school students in satisfaction, Interest, Achievement. The fluid mechanics education through engineering design and web design through the actual web server is implemented on the Internet over broadband. Department of Education, this study the fluid mechanics and the Internet will contribute to the development of distance education.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3525-3532
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• 2009

This study presents the heat transfer and pressure drop characteristics of Ag nanofluid in mini-tubes(outer diameters of 1/8inch, 3/16inch). Experiments were performed for Reynolds numbers ranged from 500 to 2,500 and nanofluid concentrations of 0.1 and 0.3vol.%. The pressure drop of nanofluid flow increased by max. 21% compared with that of distilled water. The heat transfer coefficients of the nanofluid of 0.1 vol.% enhanced 3~42% for 1/8inch tube, and 3~69% for 3/16inch tube. Also, the heat transfer coefficients of the nanofluid of 0.3 vol.% enhanced 35~65% for 1/8inch tube, and 62~125% for 3/16inch tube. From the results Ag nanofluid can be a better candidate as a coolant than distilled water when using in mechanical and/or electronic systems.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.1
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• pp.147-154
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• 2002

The dynamic load caused by sloshing of internal fluid severely affects the structural and control stabilities of cylindrical liquid containers accelerating vertically. If the sloshing frequency of fluid is near the frequency of control system or the tank structure, large dynamic force and moment act on launching vehicles. For the suppression of such dynamic effects, generally flexible ring-type baffles are employed. In this paper, we perform the numerical analysis to evaluate the dynamic suppression effects of baffle. The parametric analysis is performed with respect to the baffle inner-hole diameter and two different baffle spacing types : equal spacing with respect to the tank and one with respect to the fluid height. The ALE (arbitrary Lagrangin-Eulerian) numerical method is adopted for the accurate and effective simulation of the hydrodynamic interaction between fluid and elastic structure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1247-1252
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• 2014

In the present study, sedimentation and shear stress of MR fluid are investigated to physical characteristics of MR fluid along temperature conditions. MR fluid is a suspension of micrometer-sized magnetic particles in a base liquid. Therefore, dispersion of MR fluid is important in the case of the design and optimization of the system using MR fluid. Due to sedimentation characteristics of MR fluid by magnetic particles, the sedimentation and shear stress of commercial MR fluid are investigated at $25^{\circ}C$ and $80^{\circ}C$ temperatures by using a forced convection oven and a viscometer. From experimental results, the sedimentation and shear stress are more affected by the temperatures of $80^{\circ}C$ than $25^{\circ}C$ and the mixing time of 5min than 10min. Shear stress by the applied current increases the shape of a quadratic equation and are lower 6-18% at $80^{\circ}C$ than $25^{\circ}C$.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.3
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• pp.1-12
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• 2012

In this study, an analysis method for the earthquake response of an offshore wind turbine model is developed, considering the effects of the fluid-structure-soil interaction. The turbine is modeled as a tower with a lumped mass at the top of it. The tower is idealized as a tubular cantilever founded on flexible seabed. Substructure and Rayleigh-Ritz methods are used to derive the governing equation of a coupled structure-fluid-soil system incorporating interactions between the tower and sea water and between the foundation and the flexible seabed. The sea water is assumed to be a compressible but non-viscous ideal fluid. The impedance functions of a rigid footing in water-saturated soil strata are obtained from the Thin-Layer Method (TLM) and combined with the superstructure model. The developed method is applied to the earthquake response analysis of an offshore wind turbine model. The method is verified by comparing the results with reference solutions. The effects of several factors, such as the flexibility of the tower, the depth of the sea water, and the stiffness of the soil, are examined and discussed. The relative significance of the fluid-structure interaction over the soil-structure interaction is evaluated and vice versa.

• Fire Science and Engineering
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• v.33 no.3
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• pp.37-43
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• 2019

In this study, ethanol pool fire extinguishing experiments were conducted using a twin-fluid nozzle. Ethanol pool fires, 5.027×10^-3 ㎡ and 1.131×10^-2 ㎡ in size (80 mm and 120 mm in fuel pan diameter, respectively), were tested, and the flow rates supplied to the twin-fluid nozzle for fire extinguishing were 156-483 g/min and 20-70 L/min for water and air, respectively. The heat release rate increased with increasing fire source area, and heat release rates of 5.027×10^-3 ㎡ and 1.131×10^-2 ㎡ in size were measured to be 1.01 kW and 5.51 kW, respectively. For both fire source cases in the present experimental range, regardless of the water flow rates, the ethanol fires were extinguished successfully under the high air flow rate condition (e.g., above 40 L/min). On the other hand, under all water flow rate conditions, the fire extinguishing time and water consumption decreased with increasing air flow rate, which were approximately 23 s and 185 g under high air flow rate conditions (e.g., above 50 L/min), respectively. Based on the water consumption per heat release rate, the present experimental data were compared with the previous ones using a single-fluid nozzle, and it was found that the twin-fluid nozzle could extinguish a fire with a lower water consumption than a single-fluid one.

• KSBB Journal
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• v.20 no.3
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• pp.205-209
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• 2005

Studies for the commercial production of sesame oil using th supercriticl carbon dioxide were made. Characteristics of sesame oil containing one of natural antioxidant 'sesamol', which only exist at sesame seed were also studied during the supercritical fluid extraction. Among the various factors influencing the sesamol contents in the sesame oil, the roasting time and temperature were checked, because sesamol can be converted from sesamol in through pyrolysis. We found that the sesamol content was increased rapidly under the condition of roasting temperature over $200^{\circ}C$ with longer roasting time. The sesamol content was increased as the temperature and pressure increased, which was caused by increase of solubility of sesamol against sesamol oil. And the sesamol content was increased also with lower speed of supercritical fluid, which increased the contact time with the raw material. The sesamol content was also increased using water increase up to $1\%$ as the entrainer. When the extraction performance with the supercritical fluid was compared to the conventional compressed extraction, the sesamol content was increased up to 11.5 times with the entrainer.

• 열병합발전
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• s.71
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• pp.3-9
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• 2009

최근 국내 발전분야 최고 관심사는 직렬형 축을 가지는 1000MW 이상의 대용량 고효율 증기터빈 개발 및 운영이다. 발전 산업계 요구를 충족시키기 위하여 터빈 설계사들은 새로운 대용량의 저압터빈 실린더 모듈을 개발하고 있는데 개발된 모듈의 특징은 진보된 유체역학과 구조적 분석 기술을 결합하고 기존 합금강 재질 최종단 익에 작용하는 응력한계 길이인 1000mm 이상 길이의 최종단 날개를 개발하는 것이다. 본 논고에서는 Alsthom사에서 새롭게 개발된 최종단 익(翼)의 공역학 및 기계적 특성 설계 개발내용과 실증시험 결과를 소개하고자 한다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.469-474
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• 1998

이상 유동 지배 방정식에 두 상의 경계면 두께 개념을 도입하여 액체 내부에서의 기포 거동에 대한 동적 안정성을 이론적으로 해석하였다. 현재까지 기포의 안정성은 실험과 거시적인 물리적 이론에 의하여만 정적으로 연구되어 왔으나, 상간의 압력 불연속성을 표면장력 모델링을 이용하여 해석적으로 해결 함으로서 기포 안정성에 대한 정량적인 분석을 가능하게 하였다. 그 결과 기포의 안정성은 기존의 무차윈 Weber수 이외에 Reynolds수 그리고 유체의 점성력과 Capillary파와 관련된 무차원 수에 의해서도 영향을 받는 것으로 밝혀졌다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1493-1498
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• 2010

This paper present the characteristics of micro- and meso-scale milling processes in which compressed cold air, minimum quantity lubrication (MQL) and $MoS_2$ nanofluid MQL are used. For process characterization, the microand meso-scale milling experiments are conducted using desktop meso-scale machine tool system and the surface roughness is measured. The experimental results show that the use of compressed chilly air and nanofluid MQL in the micro- and meso-scale milling processes is effective in improving the surface finish.