http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
박준권(J.K. Park),강관형(K.H. Kang) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5
Recently, several open source codes for computational fluid dynamics (CFD) have been emerged and are spreading fast. Our group has chosen OpenFOAM as a platform to develop our own in-house code. In this paper, we would like to share the information on the codes and what we have experienced so far. We introduce several features of OpenFOAM, which include the performance compared with commercial packages, estimation for current user population, and our own prospect for future improvement in performance and growth in user population. In addition, we briefly introduce our experience gained in embedding the level set method into the OpenFOAM.
레벨셋 기법을 이용한 전기습윤 현상의 동적 거동에 대한 해석
박준권(J.K. Park),홍지우(J.W. Hong),강관형(K.H. Kang) 한국전산유체공학회 2009 한국전산유체공학회 학술대회논문집 Vol.2009 No.11
Electrowetting is a versatile tool to handle tiny droplets and forms a backbone of digital microfluidics. Numerical analysis is necessary to fully understand the dynamics of electro wetting, especially in designing electro wetting-based devices, such as liquid lenses and reflective displays. We developed a numerical method to analyze the general contact-line problems, incorporating dynamic contact angle models. The method is based on the conservative level set method to capture the interface of two fluids without loss of mass. We applied the method to the analysis of spreading process of a sessile droplet for step input voltages and oscillation of the droplet for alternating input voltages in electro wetting. The result was compared with experimental data. It is shown that contact line fiction significantly affects the contact line motion and the oscillation amplitude. The pinning process of contact line was well represented by including the hysteresis effect in the contact angle models.
레벨셋 기법을 이용한 전기습윤 현상의 동적 거동에 대한 해석 및 물성 보간 방법에 대한 고찰
박준권(J.K. Park),강관형(K.H. Kang) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5
Electrowetting is a versatile tool to handle tiny droplets and forms a backbone of digital microfluidics. Numerical analysis is necessary to fully understand the dynamics of electrowetting, especially in designing electrowetting-based devices, such as liquid lenses and reflective displays. We developed a numerical method to analyze the general contact-line problems, incorporating dynamic contact angle models. The method is based on the conservative level set method to capture the interface of two fluids without loss of mass. We applied the method to the analysis of spreading process of a sessile droplet for step input voltages and oscillation of the droplet for alternating input voltages in electrowetting. The result was compared with experimental data. It is shown that contact line friction significantly affects the contact line motion and the oscillation amplitude. The pinning process of contact line was well represented by including the hysteresis effect in the contact angle models. In level set method, in the mean time, material properties are made to change smoothly across an interface of two materials with different properties by introducing an interpolation or smoothing scheme. So far, the weighted arithmetic mean (WAM) method has been exclusively adopted in level set method, without complete assessment for its validity. We showed here that the weighted harmonic mean (WHM) method for rate constants of various rate processes, including viscosity, thermal conductivity, electrical conductivity, and permittivity, can be an alternative. I.e., the WHM gives more accurate results than the WAM method in certain circumstances. The interpolation scheme should be selected considering various characteristics including type of property, ratio of property of two fluids, geometry of interface, and so on.
ASSESSMENT OF PROPERTY INTERPOLATION METHODS IN LEVEL SET METHOD
J.K. Park(박준권),J.M. Oh(오정민),K.H. Kang(강관형) 한국전산유체공학회 2009 한국전산유체공학회 학술대회논문집 Vol.2009 No.4
In level set method, material properties are made to change smoothly across an interface of two materials with different properties by introducing an interpolation or smoothing scheme. So far, the weighted arithmetic mean (WAM) method has been exclusively adopted in level set method, without complete assessment for its validity. We showed here that the weighted harmonic mean (WHM) method for rate constants of various rate processes, including viscosity, thermal conductivity, electrical conductivity, and permittivity, gives much more accurate results than the WAM method. The selection of interpolation scheme is particularly important in multi-phase electrohydrodynamic problems in which driving force for fluid flow is electrical force exerted on the phase interface. Our analysis also showed that WHM method for both electrical conductivity and permittivity gives not only more accurate, but also more physically realistic distribution of electrical force at the interface. Our arguments are confirmed by numerical simulations of drop deformation under DC electric field.
박준권(J.K. Park),강관형(K.H. Kang) 한국전산유체공학회 2010 한국전산유체공학회지 Vol.15 No.3
Recently, several open source codes for computational fluid dynamics (CFD) have been introduced and are spreading fast. Our group has chosen the OpenFOAM as a platform to develop our own in-house code. In this brief review, we would like to share the information on the codes and what we have experienced so for. We introduce several features of OpenFOAM, which include the performance compared with commercial packages, estimation for current user population, and our own prospect for future improvement in performance and growth in user population. In addition, we briefly introduce our experience gained in embedding the level set method into the OpenFOAM.
레벨셋 기법을 이용한 전기습윤 현상의 동적 접촉각 문제에 대한 수치해석
박준권(J.K. Park),강관형(K.H. Kang) 한국전산유체공학회 2009 한국전산유체공학회 학술대회논문집 Vol.2009 No.4
We developed a numerical method to analyze the contact-line problems, incorporating a dynamic contact angle model. We used level set method to capture free surface. The method is applied to the analysis of dynamic behavior of a droplet in DC electro wetting. The result is compared with an experimental data and result of perturbation method.
한국 밀식사과원의 정지전정에 따른 수체생장과 생산성 및 경영효율 비교
정혜웅,김경훈,송태영,홍성일,한호균,김귀권,신종협,여덕환,김병철,박준권,Jung, H.W.,Kim, K.H.,Song, T.Y.,Hong, S.I.,Han, H.K.,Kim, K.K.,Shin, J.H.,Yeo, D.H.,Kim, B.C.,Park, J.K. 국립한국농수산대학교 교육개발센터 2017 현장농업연구지 = Journal of practical agricultural resear Vol.19 No.1
The present study conducted a comparison on tree growth and productivity of high-density apple orchards by several orchard management systems: making scaffolds by heading-back and thinning out pruning (T-1), maintaining scaffolds upward and bearing shoots downward (T-2), managing branches slightly upward without heading-back (T-3), keeping leaders downward and shoots pending (T-4), maintaining leaders high and branches horizontal with severe pinching (T-5), making leaders with lower branches vigorous and upper shoots pending (T-6), and controlling very high planting density with bending branches (T-7). In conclusion, the orchards of (T-5) and (T-6) management systems showed a superior performance in controlling tree growth, productivity, and quality of fruits. Also, superior management efficiency was obtained in the orchards of (T-5) and (T-6).