• Journal of Energy Engineering
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• v.4 no.3
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• pp.402-406
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• 1995

다리우스 풍력터빈의 속도설정을 터빈이 만드는 토크와 발전기가 요구하는 토크의 \평형을 통해 찾아 낼 수 있음을 검토하였다. 풍속에 따른 속도-토크곡선에서 일정충력곡선이 만나는 점이 터빈의 동작점으로 되며 이는 안정 및 불안정이 될 수도 있다. 풍속과 출력이 각각 변할 때 이 동작점이 어떻게 이동되는가 하는 점을 제시하였다. 또한 터빈의 속도에 관한 제어 블록선도를 제시하여 그 출력변화에 따른 속도변화의 전달함수를 알아내고 이의 형태는 1차 시지연 함수로 유도된다.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2003.04a
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• pp.195-198
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• 2003

자갈축열 태양열온실은 주간에 일사로 데워진 온실 내부공기를 온실하부에 설치된 자갈축열층사이로 강제순환시켜 자갈에 에너지를 축열한다. 이러한 축열과 방열과정을 통하여 겨울철 야간에 난방시스템으로 이용하고, 여름철에는 냉방효과를 꾀하게 된다. 온실내 공기가 축열층을 통과하는 동안의 열전달은 강제대류열전달이며, 이 경우 축열층내의 열이동은 축열층내 공기와 자갈표면온도가 초기에는 열적으로 평형상태로 존재하다가 순환공기의 온도상승에 따라 열전달이 일어나게 된다. (중략)

• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.5-11
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• 2004

생체 시스템은 수많은 세포들로 구성되어 있다. 일반적으로 세포막은 단백질과 지방의 혼합체로 구성되어 있으며 두께는 7.5-10nm 정도이다. 단백질은 지방과 함께 세포막을 통한 물질의 이동을 제어하는 역할을 한다. 특히 지방층은 지방에 잘 용해되는 산소나 탄산가스 등은 잘 통과시키지만, 지방에 잘 용해되지 않는 나트륨, 칼륨, 칼슘, 글루코스, 아미노산 등은 지방층 내부에 삽입되어 있는 단백질에 의해 조절된다.(중략)

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.1
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• pp.39-48
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• 2013

This paper develops a 2-D moving least squares(MLS) difference method for Stefan problem by extending the 1-D version of the conventional method. Unlike to 1-D interfacial modeling, the complex topology change in 2-D domain due to arbitrarily moving boundary is successfully modelled. The MLS derivative approximation that drives the kinetics of moving boundary is derived while the strong merit of MLS Difference Method that utilizes only nodal computation is effectively conserved. The governing equations are differentiated by an implicit scheme for achieving numerical stability and the moving boundary is updated by an explicit scheme for maximizing numerical efficiency. Numerical experiments prove that the MLS Difference Method shows very good accuracy and efficiency in solving complex 2-D Stefan problems.

• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.843-850
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• 2002

Linear transformation theory has been effectively used in the design and analysis of prestressed concrete structures. The underlying assumptions of the theory, which were often overlooked, are investigated in the respect of equivalent load method. As a result, it is found that the same equivalent loading system is produced for all the cases of the linear transformation by the assumptions of the conventional equivalent load method. On the other hand, equivalent loading systems in a strict and accurate sense do not satisfy the classical theories of the linear transformation. Also, it is shown that a little different equivalent loading system from the conventional one is obtained for each linear transformation according to the proposed equivalent load method that is derived from the self-equilibrium property of the tendon-induced forces. Therefore, it can be concluded that the linear transformation theory is valid only when referring to the conventional approximate equivalent load method. The discussions are further extended to the eccentrically located circumferential tendon in the wall of containment structures, where the problem of eccentricity is analyzed also from the view point of the linear transformation.

• Journal of Navigation and Port Research
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• v.28 no.6
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• pp.469-474
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• 2004

In this paper, we study the posture control of an underwater vehicle with nonholonomic constraint. Generally, systems with nonholnomic constraints cannot be stabilized to an equilibrium points by smooth state feedback control. For the nonholonomic underwater vehicle system, we applied coordinate transformation to get multi-chained system We proposed non smooth feedback controller using backstepping method for stabilizing the multi chained form system Applying inverse input transformation to the non smooth feedback controller, we can get posture controller of the underwater vehicle with nonholonomic constraint. The proposed control scheme is applied to the posture control qf an underwater vehicle and verified the effectiveness of control strategy by numerical simulation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.4
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• pp.348-353
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• 2008

Oxygen isotope has not been used actively in water mass studies because of difficulties on the analysis though it has advantages as a water mass tracer. The most popular method to analysis the oxygen isotope ratio in water samples is equilibration method: isotopic equilibrium of water with $CO_2$ at constant temperature. The precision of oxygen isotope analysis using commercial automatic $H_2O/CO_2$ equilibrator is ${\pm}0.1%o$. This value is not sufficient for studies in open ocean. The object of this study is to improve the analytical precision enough to apply open ocean studies by modification of the instrument. When sample gas is transferred by the pressure difference, the fractionation which is preferential transportation of light isotope can be occurred since the long transportation path between the equilibrator and mass spectrometer. And the The biggest source of error during the analysis is long distance and large volume of the pathway of sample gas between. Therefore, liquid nitrogen trap and high vacuum system are introduced to the system. The precisions of 14 time analysis of same seawater sample are ${\pm}0.081%o$ and ${\pm}0.021%o$ by built-in system and by modified system in this study, respectively.

• Radiation Oncology Journal
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• v.17 no.3
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• pp.223-229
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• 1999

Purpose : The expression pattern of c-jun by ionizing radiation according to cell growth state (exponential growth vs. stationary phase) and its relationship with cell cycle redistribution were investigated. Materials and Methods : The exponential growth phase (day 4) and stationary phase (day 9) cells were determined from cell growth curve according to the elapse of days in CaSki. The cells were irradiated using 6 MV X-ray with a dose of 2 Gy at a fixed dose rate of 3 Gy/min. Northern blot analysis was peformed with total cellular RNA and cell cycle distribution was analyzed using flow cytometry according to time-course after irradiation. Results : The maximum expression of c-jun occurred 1 hour after irradiation in both exponential growth and stationary phase cells. After then c-jun expression was elevated upto 6 hours in exponential growth phase cells, but the level decreased in stationary phase cells. Movements of cells from G0-G1 to S, G2-M phase after irradiation were higher in exponential growth phase than stationary phase. Conclusion : c-jun may be involved in the regulation of cellular proliferation according to the growth states after irradiation.

• Journal of computational fluids engineering
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• v.17 no.2
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• pp.107-112
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• 2012

We explored the dynamic motions and the lateral equilibrium positions of an elastic capsule in channel flow at moderate Reynolds number varying Re, aspect ratio, size ratio, membrane stretching and bending coefficient. The transition of tank-treading/swinging to tumbling motion was observed in the simulations and the transition of dynamic motions for capsules resulted in different trend of the variation in the lateral equilibrium positions. Though other conditions were similar, the capsule with tumbling motion migrated closer to the wall than that with tank-treading motion.

• KSBB Journal
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• v.4 no.2
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• pp.150-156
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• 1989

The chaacterisitics of a commercial membrance-coverd electrode in air-saturated saline solution were investigated in terms of a steadystate one-dimensional model. The electrode system miiersed in an aqueous medium consists of three layers: an external concentration boundary layer, a membrance, and an inner electrolyte layer. The membrance can be permeabld to the water and impermeable to the ionic species. In stationary midium, the water migrates from the external medium to the inner electrolyte layer until a thermodynamic equilibrium is reached. In a following midium, however, there is a reverse direction of water movement due to the hyrodynamic pressure differential until both thickness of the electrolyte layer and the membrance are equal.