• Korean Journal of Plant Resources
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• v.19 no.4
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• pp.517-520
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• 2006

The effects of culture soil combinations on growth of native pteridophyte (Pteris multifida, Cyrtomium falcatum and Cheilanthes argentea) were investigated in this study. Six different culture soil mixtures used for cultivating the pteridophytes under 30% shading condition. Pteris multifida was showed the most growth at the culture soil mixtures of peatmoss : living moss (5 : 5), and peatmoss : perlite (7 : 3). Cyrtomium falcatum and Cheilanthes argentea showed the best growth in the culture soils mixtures of sand : soil : leaf mold (2 : 5 : 3) and peatmoss : perlite (7 : 3, 5 : 5), respectively.

• Journal of the Korean Electrochemical Society
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• v.3 no.3
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• pp.173-177
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• 2000

The synthetic carbon was coated with tin oxide and copper by fluidized-bed chemical vapor deposition method. $(CH_3)_4Sn\;and\;Cu(hfac)_{2s}$ were employed as the metallic organic precursor, respectively. The modified synthetic carbons were used for lithium secondary battery anode to investigate their coating effects on electrochemical characteristics as alternative anode materials for lithium secondary batteries. The electrode which prepared by the synthetic carbons(MCMB) coated with tin oxide gave the higher capacity than that of raw material. Their capacity decreased with the progress of cycling possibly due to severe volume changes. But the cyclability was improved by coating with copper on the surface of the tin oxide coated carbon, which plays an important role as an inactive matrix buffering volume changes.

• Nuclear Engineering and Technology
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• v.25 no.2
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• pp.233-236
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• 1993

For one-dimensional two-phase flow without phase change and without axially-temporally rapid change of pressure, the interrelationship between the drift-flux model and the two-fluid model is studied. It is derived on the basis of the fact that the vapor conservation equation is related to the momentum equation by the drift flux. Starting from the two-fluid model, we obtain the interfacial friction expressed in terms of drift-flux parameter. Also, by deriving the void propagation equation, the drift-flux is shown to have jnterrelationship with forces in the two-fluid model.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.250-254
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• 2003

본 연구에서는 여러가지 해석해를 이용하여 균열암반 대수층에서 얻어진 양수시험자료를 해석하였다. 균열암반 대수층의 수리적 특성을 연구해 본 결과, 1.3차원에서 2.9차원까지 다양한 분포 차원을 나타나며, 양수시험 자료중 52%에 해당하는 자료가 1차원과 2차원 사이의 분할 유동차원을 보여준다. 이에 대하여 6.3%만이 Theis 이론에 맞는 2차원의 방사상 흐름을 보여준다 2∼3차원의 대수층이 암반대수층에서 나타나기는 어려우며, 만약 2차원 이상으로 해석되는 경우는 다른 방향으로 해석하는 것도 검토해야 한다. 즉, Leaky, constant head boundary, no flow boundary 등을 고려해야 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.776-779
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• 2009

P2P(Peer-to-Peer) 기반에 분산 작업 할당의 경우 정해진 수의 모든 피어에 작업을 분배하는 방식으로 처리하기 때문에 한 피어에 작업량이 증가하는 경우나 피어에 문제가 발생하는 경우 이를 사전에 예측하지 못해 시스템에 문제가 발생하게 된다. 또한 P2P 형태의 특성 상 피어의 그룹 참여는 유동적이며 그룹에 참여하는 피어의 사양도 다양하게 존재하게 된다. 이와 같은 상황에서는 작업을 할당하더라도 작업 진행이 이루어지지 않을 확률이 높아지고 전반적으로 시스템의 성능을 저하시키는 문제점을 가지게 된다. 본 논문에서는 이러한 문제점을 해결하기 위해서 인공지능 알고리즘의 하나인 유전자 알고리즘(Genetic Algorithms: GA)를 활용하여 피어의 상태를 사전에 예측하여 작업 분배 시 동적으로 작업할 피어를 선택하여 처리하는 P2P기반 동적 작업할당 관리자를 설계하였다.

• Applied Chemistry for Engineering
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• v.35 no.2
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• pp.115-121
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• 2024

This study analyzed the influence of process variables affecting the thermodynamic equilibrium and fluid dynamics of interfaces such as reverse micelle, salt concentration, interfacial tension, and viscosity of fluids to optimize the microencapsulation process using the W1/O/W2 double emulsion method. The process variable with the greatest impact on encapsulation efficiency was found to be the difference in osmotic pressure between the W1 and W2 phases. It was observed that increasing the salt concentration in the W2 phase or decreasing the ascorbic acid concentration in the W1 phase resulted in higher encapsulation efficiency. Additionally, a larger difference in osmotic pressure led to increased damage to the surface of the microparticles, as confirmed by SEM images. The introduction of reverse micelles, which was anticipated to increase encapsulation efficiency, either had a low contribution or even decreased encapsulation efficiency. The yield of microcapsules was expressed as a universal function, applicable to all process conditions or solution compositions. According to this universal function, no further increase in yield was observed beyond the Ca (capillary number) of approximately 20.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.190.1-190.1
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• 2010

풍력자원평가를 위해 풍력단지 개발대상지의 국지풍황 대표지점에 설치하는 풍황탑(met-tower 또는 풍황마스트; met-mast)은 모노폴(monopole), 삼각단면 트러스 또는 사각단면 트러스 구조를 갖는다. 풍향계 및 풍속계는 이러한 지지구조물에 의한 풍속의 교란 또는 차폐영향을 최소화하기 위하여 긴 붐(boom)의 끝단에 설치되지만 계측기가 풍황탑의 직후방 후류영역에 놓이게 될 경우 차폐영향을 완전히 피하기는 어렵다. 저자들의 선행연구에 따르면 풍황탑 차폐영향은 평균풍력밀도의 경우 2.5% 이상의 오차를 유발할 수 있으므로 풍력자원평가 시 필히 고려되어야 할 불확도 요인인 것이다. 이에 한국에너지기술연구원에서는 풍황탑 주위의 대기유동장을 전산유동해석을 이용하여 차폐영향의 정도를 정량적으로 수치모사함으로써 이를 보정하는 기술을 개발한 바 있다(현재 특허심사 중). KIER-$ShadeFree^{TM}$는 이 특허기술을 프로그램화 한 것으로, 시범적으로 다수의 풍황탑 풍력자원 측정자료에 적용하여 상당한 보정효과에 의한 풍력자원평가의 정확도 향상효과를 볼 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.1
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• pp.9-16
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• 2014

This paper presents the theoretical analysis of a flow driven by surface tension and gravity in an inclined circular tube. A governing equation is developed for describing the displacement of a non-Newtonian fluid(Power-law model) that continuously flows into a circular tube owing to surface tension, which represents a second-order, nonlinear, non-homogeneous, and ordinary differential form. It was found that quantitatively, the theoretical predictions of the governing equation were in excellent agreement with the solutions of the equation for horizontal tubes and the past experimental data. In addition, the predictions compared very well with the results of the force balance equation for steady.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.8 s.251
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• pp.780-787
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• 2006

Several types of different header designs are numerically studied to have uniform distribution of two phase flow in the evaporator header having multi-channels. The different geometries include the inlet tube position into the header and the width of header. In the numerical calculation, two types of two-phase model such as homogeneous model and VOF(Volume Of Fluid) model are employed. In this study, the mal-distribution number, $M_d$, is newly defined to evaluate the averaged level of the flow distribution in the whole passes of the evaporator. As results, two phase flow in the header can be visualized using post-processing of numerical results. Furthermore, the optimum position of the inlet tube into the header and the width of header can be proposed for the better distribution of refrigerant(R-134a) flow.

• Journal of Ocean Engineering and Technology
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• v.26 no.1
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• pp.9-16
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• 2012

This paper presents the numerical results of a simulation of the free surface flow around a blunt bow ship model and focuses on the validation of the proposed method with a brief investigation of the relation between the resistance and free surface behavior. A finite volume method based on the Reynolds Averaged Navier-Stokes (RANS) approach is used to solve the governing flow equations, where the free surface, including wave breaking,is captured by using a two-phase Level-Set (LS) method. For turbulence closure, a two equation k-${\varepsilon}$ model with the standard wall function technique is used. Finally, the numerical results are compared with the available experimental data, showing good agreement.