• Journal of Fisheries and Marine Sciences Education
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• v.20 no.3
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• pp.442-451
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• 2008

The purpose of this study is to analyze the impacts of the rapid rise in oil prices on fisheries economy. Even though fishery oils are tax exemption items, such increase in oil prices put a great amount of pressure on Korean fishing operations. Because basically the recent oil shock is externally given, Korean fisheries themselves have little capacity to cope with the disruption of economic environments. The research results turned out that Korean fisheries are extremely vulnerable(or fragile) to external shocks. In this regard, government support issues of oil costs are in the center of debate. It is widely recognized that direct/indirect government financial supports or subsidies would result in economic inefficiency in expense of equity. However, there are second best theories which may justify government intervention into the markets. This second best theory is translated into the constitutional law that instructs the government to protect and promote the primary industries including fisheries, agriculture, and midium/small-scale enterprises. It is apparent that the constitutional law would provide the government with a variety of policy instruments such as more active buy-back programs, tax exemptions and technological development to deal with fisheries economic hardship due to the external pressure such as high oil prices and international fishery orders.

• Clinical Pain
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• v.18 no.2
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• pp.142-146
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• 2019

This is a case report of the provocative discographic findings before and after focal selective coagulation of the major annular fissure using intradiscal navigable catheter. A 46-year-old woman had a 30-month history of axial low back pain and magnetic resonance imaging findings suspicious for painful L4/5 disc. The provocative discography confirmed painful disc before coagulation. The final electrode tip position in the coagulation procedure was at the largest fissure within the outer annular margin identified through the discography. Six months after the successful coagulation therapy, inadvertently performed discography resulted in decreased pressure rise over time. Neither evoked pain nor change in the integrity of outer annulus as compared with the previous results was reported. Such an interventional method has not been reported previously, and the analytic results suggest that it may be possible to relocate the pressure of the entire nucleus pulposus only by focal selective coagulation of the fissure.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.337-345
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• 2002

The present study addresses a computational result of unsteady gas flow through a critical nozzle. The axisymmetric, unsteady, compressible, Wavier-Stokes equations are solved using a finite volume method that makes use of the second order upwind scheme for spatial derivatives and the multi-stage Runge-Kutta integral scheme for time derivatives. The steady solutions of the governing equation system are validated with the previous experimental data to ensure that the present computational method is valid to predict the critical nozzle flows. In order to simulate the effects of back pressure fluctuations on the critical nozzle flows, an excited pressure oscillation with an amplitude and frequency is assumed downstream of the exit of the critical nozzle. The results obtained show that for low Reynolds numbers, the unsteady effects of the pressure fluctuations can propagate upstream of the throat of critical nozzle, and thus giving rise to the applicable fluctuations in mass flow rate through the critical nozzle, while for high Reynolds numbers, the pressure signals occurring at the exit of the critical nozzle do not propagate upstream beyond the nozzle throat. For very low Reynolds number, it is found that the sonic line near the throat of the critical nozzle remarkably fluctuateswith time, providing an important mechanism for pressure signals to propagate upstream of the nozzle throat, even in choked flow conditions. The present study is the first investigation to clarify the unsteady effects on the critical nozzle flows.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.6
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• pp.72-78
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• 2003

In the present paper, computational studies on the hydrodynamic behavior of the inducer for the rocket-engine turbopump are presented including the effect of the mass flow rate. As the mass flow rate is increased, the inducer showed better performance with weak back flows which may have deleterious effects upon the anti-cavitation ability. But the adopted inducer showed low head rise with high volume flow rates, which may be caused by the small passage area near the trailing edge. The static pressure distributions at the shroud surface are compared with experimental results showing very good agreements except near the leading edge where strong back flows are present. The overall performance of the inducer such as, efficiency, head rise is also compared with experiments. The computational results are generally in good agreements with experimental ones near the design point, but two results show discrepancy at the high flow rate.

• Journal of Fashion Business
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• v.6 no.3
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• pp.84-93
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• 2002

The purpose of this study was to design functional clothing based on the physical characteristics of old women. The subjects of this experiment were 5 healthy old women and 5 college women. While the subjects were exposed to the circumstances of $28{\pm}0.5^{\circ}C$ and local heating at 7 areas (chest, abdomen, back, loin, hand, thigh and instep), their skin temperature, physiological reaction and psychological reaction were determined. The conclusions about the effects of local heating are as follows : 1. Skin temperature before heating was in the order of head-neck> trunk> upper limbs> lower limbs (Group A: old subjects) and head-neck> trunk> lower limbs> upper limbs (Group B: young subjects). 2. The heating pad was attached and detached for 30 minutes each. The sharpest rise and fall were recorded at 5 minutes with the pad on and off. Both groups had great changes in the body parts near trunk. 3. With the pad on and off, both groups showed no change in body temperature, blood pressure, and pulse rate. 4. Concerning the pervasive effects of local heating on whole body skin temperature, loin heating greatly increased other body parts in Group A. In Group B, the effects were large in heating chest, abdomen, back, loin, and thigh. 5. The loin part of old women has the greatest pervasive effect of local body heating.

• Fire Science and Engineering
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• v.24 no.6
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• pp.153-159
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• 2010

In this study, we confirmed the fact that air egress velocity of pressure differential system installed at vestibule of smokeproof stairway in domestic high-rise building becomes back-flow to stair-lobby at upper vestibule. Rather it do not back-flow to the livingroom. when fire occur and the door opens to escape from fire zone. so we carry out actual and computational fluid dynamics measurement. In the case upward 45 gradient of supply damper's blade, The simulation results that air flow of upper vestible is steady but back-flow phenomenon occurred at the bottom. However, in the case of $4m^2$, direction of the flow was ideal to living room. If a vestibule’s area is smaller, it must be designed and built according to performance-based design.

• Journal of the Society of Disaster Information
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• v.18 no.2
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• pp.241-251
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• 2022

Purpose: In the event of a fire in a high-rise building, if the smoke control area is not effectively protected, smoke or flames enter the stairwell, making it difficult to evacuate. When inflowing air is discharged from a closed corridor, a negative pressure is formed in the corridor, the pressure in the smoke control area becomes excessively high, and the force required to open the door during evacuation is exceeded. Also, if the air introduced into the hallway is not exhausted, the smoke may flow back into the smoke control area. This paper tried to identify the problems caused by the inflowing air and to find out how to improve the performance. Method: Using the CONTAM program, simulations were performed with the basic conditions and the modified conditions. Result: If the inflowing air was discharged from the sealed corridor, overpressure occurred in the Smoke Control Area and exceeded the opening force, and the prevent smoke backflow was insufficient in the layer where the inflowing air was not discharged. Conclusion: "Differential pressure exhaust damper" application, simultaneous opening of two exhaust dampers, and automatic window installation between corridors and outdoors improved the exhaust performance of inflowing air.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.4
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• pp.10-20
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• 2022

The performance analysis test of the scramjet engine intake was conducted under the Mach 5 condition of the scramjet engine test facility, a free-jet ground test facility of the Korea Aerospace Research Institute. A pitot/static pressure rake installed at the rear of the isolator was designed and manufactured to measure the total pressure recovery rate and mass capture ratio, which are typical performance factors of the scramjet engine intake. The effect of the rake mounted at the rear of the isolator on the intake, the performance analysis measured by the rake, and the change in wall static pressure distribution according to the angle of attack were performed. Finally, the point at which the intake unstart occurred was confirmed by using the rear back pressure adjusting device, which simulates pressure rise in the combustor, and the results are summarized in this paper.

• Proceedings of the KIEE Conference
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• summer
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• pp.1100-1102
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• 2004

열팽창 방식의 가스차단기는 아크 에너지 자체를 이용하여 압력상승을 얻고, 상승된 압력을 이용하여 전류 영점 부근에서 아크 방향으로의 유동을 형성하여 아크를 소호한다. 대전류 구간에서 노즐 폐색현상이 일어나면 노즐 용삭이 크게 일어나며 용삭된 노즐 물질은 팽창실의 압력과 온도를 상승시키게 된다. 따라서 차단 특성해석을 위해서는 노즐 용삭에 의한 압력 상승해석이 필요하다. 본 논문에서는 아크에너지에 따른 노즐 용삭비를 이용하여 용삭되는 노즐량을 계산하고, 이로 인한 back flow현상을 고려한 해석 방법을 제안한다. 개발된 프로그램을 제작한 차단부 모델에 적용한 결과, 열팽창실의 압력상승치는 시험결과와 잘 일치함을 확인하였다.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.4
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• pp.344-351
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• 2009

A multi-zone model was used to predict the operating range of homogeneous charge compression ignition (HCCI) engine, the boundaries of the operating range were determined by knock (presented by ring intensity), misfire (presented by sensitivity of indicated mean effective pressure to the initial temperature). A HCCI engine fueled with Di-Methyl Ether (DME) was simulated under different initial temperature and equivalence ratios, and the operating range was well produced by the model. Furthermore, the model was applied to develop the operating range for thermal stratification in the preceding condition of initial temperature and equivalence ratios. The computations were conducted using Senkin application of the CHEMKINII kinetics rate code.