• 대한기계학회논문집 C: 기술과 교육
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• 제3권1호
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• pp.45-53
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• 2015

해양플랜트에서 생산된 석유 또는 가스를 파이프라인을 통해 운반하는 경우, 가스 하이드레이트나 왁스와 같은 고형물이 쉽게 발생하고 이를 방지하기 위한 유동 안정성을 확보하는 것이 매우 중요하다. 해양플랜트 파이프라인에서 생성된 가스 하이드레이트 또는 왁스를 제거 또는 방지하기 위해 최근 파이프라인 외벽에 히터를 감아 전기적으로 가열하는 방법이 채택되고 있다. 본 연구에서는 파이프라인을 가열하는 기존의 외부 가열형 방식에 비해, 새로운 형식의 내부 스월형 히터를 고안, 설계 및 제작하여 파이프라인 내에 설치하여 유동 안정성을 실험적으로 평가하였다. 고안된 내부 스월형 히터와 기존의 외부 가열형 히터의 파이프라인 출구 단면에서의 온도 분포와 열적 혼합 등의 열 및 유동 성능 평가 결과, 내부 스월형 히터가 외부 가열형 히터에 비해 열적 성능이 보다 우수한 것으로 확인되었다.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.2010-2018
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• 2003

Although continuous casting process has highly developed, there still remain many problems to be considered. Specifically, two vortex flows resulting from impingement against narrow walls make a flow field unstable in a mold, and it is directly related to internal and external defects of steel products. To cope with this instability, EMBR (Electromagnetic Brake Ruler) technique has been lately studied for the stability of molten steel flow, and it is revealed that molten steel flow in a mold can be controlled with applied magnetic field. However, it is still difficult to clarify flow pattern in an EMBR caster due to complex correlations among variables such as geometric factors, casting conditions, and the place and the intensity of charged magnetic field. In the present study, flow field in a mold is focused with different conditions of electromagnetic effect. To accurately analyze the case, three dimensional low Reynolds turbulent model and appropriate boundary conditions are chosen. To evaluate the electromagnetic effect in molten steel flow, dimensionless numbers are employed. The results show that the location and the intensity of the applied magnetic field significantly influence the flow pattern. Both impingement and internal flow pattern are changed remarkably with the change of the location of applied magnetic field. It turns out that an insufficient magnetic force yields adverse effect like channeling, and rather lowers the quality of steel product.

• 한국전기전자재료학회논문지
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• 제16권10호
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• pp.931-937
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• 2003

The principle of the superconducting vortex flow transistor (SVFT) is based on control of the Abrikosov vortex flowing along a channel. The induced voltage is controlled by a bias current and a control current, instead of external magnetic field. The device is composed of parallel weak links with a nearby current control line. We explained the process to get an I-V characteristic equation and described the method to induce the external and internal magnetic field by the Biot-Savarts law in this paper. The equation can be used to predict the I-V curves for fabricated device. From the equation we demonstrated that the current-voltage characteristics were changed with input parameters. I-V characteristics were simulated to analyze a SVFT with multi-channel by a computer program.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1995년도 제5회 학술강연회논문집
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• pp.69-83
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• 1995

A great number of experimental data indicating shock-induced separation(SIS) in internal or external supersonic flows were reviewed to make clear the mechanism of SIS and to present the criterion of turbulent boundary layer separation. The interesting conclusions were obtained for the considerably wide range of flow geometries that the incipient separation is almost independent of the flow geometries, and that it is relatively unaffected by changes in gas specific heat, and boundary layer Reynolds number, Furthermore, the pressure rise necessary to separate boundary layer in external flows was found to be applicable to SIS in overexpanded propulsion nozzles. This is due to the fact that the SIS phenomenon caused by the interaction between shock waves and turbulent boundary layers is processed through a supersonic deceleration. This is, the SIS in almost all of interacting flow fields is governed by the concept of free interaction, and criterion of SIS is only a Function of upstream Mach number.

• 한국분무공학회지
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• 제9권2호
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• pp.24-33
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• 2004

The effect of the working fluid flow conditions and nozzle geometry on the spray performance of a twin-fluid nozzle used in Selective Catalytic Reduction is investigated experimentally. The liquid pressure is varied in the range of 0.3atm to 1.5atm and the air pressure is varied from the 0.5atm to 3.0atm. relative position between liquid nozzle(internal nozzle) and air nozzle(external nozzle) tip changes front 1mm inside the air nozzle to 1mm outside the air nozzle. The orifice diameter of the air nozzle is varied with 5mm. 6mm and 7mm. Spray visualization is realized with CCD-Camera. SMD(Sauter Mean Diameter) and mean particle velocities are measured by PDPA(Phase Doppler Particle Analyzer) under various experimental conditions. The measuring point is 300mm away from the nozzle tip in the downstream spray. The experimental results are that spray angle is depended air flow rate because nozzle diameter, air pressure and nozzle tip relative positions are related air flow rate. SMD is depended air flow rate and water flow rate. Also, SMD is increased when water flow rate is bigger. SMD is decreased when Air flow rate is bigger.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권6호
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• pp.692-710
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• 2018

The Three-dimensional (3-D) dynamical behaviors of a fluid-conveying pipe subjected to vortex-induced vibration are investigated with different internal flow velocity ${\nu}$. The values of the internal flow velocity are considered in both subcritical and supercritical regimes. During the study, the 3-D nonlinear equations are discretized by the Galerkin method and solved by a fourth-order Runge-Kutta method. The results indicate that for a constant internal flow velocity ${\nu}$ in the subcritical regime, the peak Cross-flow (CF) amplitude increases firstly and then decrease accompanied by amplitude jumps with the increase of the external reduced velocity. While two response bands are observed in the In-line (IL) direction. For the dynamics in the lock-in condition, 3-D periodic, quasi-periodic and chaotic vibrations are observed. A variety of CF and IL responses can be detected for different modes with the increase of ${\nu}$. For the cases studied in the supercritical regime, the dynamics shows a great diversity with that in the subcritical regime. Various dynamical responses, which include 3-D periodic, quasi-periodic as well as chaotic motions, are found while both CF and IL responses are coupled while ${\nu}$ is beyond the critical value. Besides, the responses corresponding to different couples of ${\mu}_1$ and ${\mu}_2$ are obviously distinct from each other.

• 한국소음진동공학회논문집
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• 제24권10호
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• pp.763-769
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• 2014

This study is on the experiment and prediction of the pipe noise due to the internal fluid. The vibration of pipe external surface and noise in air were measured according to the internal fluid velocity and pipe type. In the experiment, the vibration and noise level of the straight pipe and rounded pipes show that the vibration and noise level are almost same. The 900 mitred pipe shows the high vibration and noise level. In the prediction of noise due to the internal flow, the method using the pipe surface vibration and radiation efficiency shows good agreement with experimental result.

• 한국해안해양공학회지
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• 제4권2호
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• pp.91-107
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• 1992

Heaps(1972)가 사용한 천해균질류에 대한 선형 기본방정식을 수심평균류속과 해수면변리를 계산하는 External mode와 수심변이 유속을 계산하는 Internal mode로 분리시킨 다음, Internal mode식에 Galerkin Method를 적용하였다. Internal mode유속을 수평좌표, 시간에 따라 변하는 계수와 대직좌표에 따라 변하는 Basis function들의 곱의 형태로 선형전개하며, 난류확산계수를 포함하는 2차미분항으로부터 해수면에 Homogeneous boundary condition과 해저면에 Sheared boundary condition이 가해지는 Sturm-Liouville system을 구성, Eigenfunctions 해를 구하여 Basis function으로 사용하였다. 모델의 성능을 검토하기 위하여 수립된 모델을 정상균일풍이 가해지는 1차원 수노에 적용하여 Cooper and Pearce(1977)가 제시한 해저면 비활동조건하의 무한 및 유한수노 연직류원분포에 대한 해석각와 비교하였으며, North Sea 규모의 등수심 장방형 Basin(Heaps' Basin)에 적용하여 정상균일풍에 대한 Heaps(1972)의 계산결과와 비교하였다.

• 대한의료기공학회지
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• 제11권1호
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• pp.236-261
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• 2009

'Jeom-hyeol-gigong(點穴氣功)' gives a drill, Gi(氣) as a place to jam. This pathogen(邪氣) is removed. Given the low places and supplement it energy to flow up the well is the cure. This is an internal organ and muscular Gi allows a natural flow. Blood, one that moves and guides Gi is Gi I still feel that it makes any blood, making you feel good in life is flowing with vitality. Gi driving our whole body, while supplying vital energy and blood circulation, helping to defend the body is functioning. 'Jeom-hyeol-gigong' principle of Gi where the blockages to flow naturally energy is to let the flow. Aura of the voluntary and proactive action will be to have healthy bodies. Gi as a whole-body blood circulation leading to the cells in each tissue to supply energy and nutrients to every cell as the original principles of free activities that will maximize your life. Gi to prevent the three causes Internal causes: 5 greed and 7 emotions External causes: climate, food, pathogens, stress, etc. The internal nor the external causes: internal and external factors that cause the complex elements, incorrect position of the bone caused by an imbalance Heart disease will be police officers and raise their resistance to disease than the body, what jung-gi(正氣) have to develop. Beneficial to human body's resistance to raise the jung-gi people young-gi(營氣) and wi-gi(衛氣) should be enhanced. If the form is perfectly possible, Gi cycle itself should not have to breathe. Abdominal diagnosis 'bok-su-ap-an-beop(伏手壓按法)', 'sam-ji-tam-an-beop(三指探按法)' hands are like this, which outlined five viscera in order to understand the problem, the lower side of the clavicle (lung), the pit of stomach (Heart), both the lower ribs (liver), navel below (kidney) can be diagnosed at such areas. In each area of the skin, abdominal muscle tension, aching, or pressing a fuss about, beating the ruling of the state and the problem is a clue. And mo-hyeol(募穴) and certain Acupressure group, the chest, back, belly, so that scattered around each' book 'of the problem can be found. This is also the target of such a diagnosis, such as shape, color of skin, muscle Mostly the scope of the pitch in the cervical spine is broad across the hips. sugi(手氣) method that 'an method(按法) and 'ma method(摩法), bak method(拍法) is.

• 조명전기설비학회논문지
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• 제14권2호
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• pp.59-67
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• 2000

본 논문에서는 단목무성방전과 3상 전압을 사용한 중첩무성방전을 인가할 수 있는 오존발생기를 설계.제작하였다. 오존발생기는 3개의 전극(중심천극, 내부천극 및 외부전극)과 2개의 방전갭(중심전극과 내부전극 사이의 갭 및 내부전극과 외부전극 사이의 갭)으로 구성되어 있으며, 단목무성방전과 3상 중접방전이 인가되는 방식에 따라 오존화 가스가 생성된다. 이때 방전전력과 원료가스($O_2$)의 유량의 변화에 따른 오존생성특성을 연구한 결과, 단독무성방전의 경우, 최대 2300[ppm], 570[mg/h] 및 745[g/kWh]의 오존생성특성을 얻을 수 있었으며,3상 전압을 인가한 경우에는 5039[ppm], 1773[mg/h] 및 851[g/kWh]을 각각 얻을 수 있었다. 따라서 3상 중첩무성방전 이 단독무성방전에 비하여 오존생성특성올 향상시킬 수 있음을 확인하였다.