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EMBR을 이용한 연속주조공정에서 난류 유동, 상변화 및 매크로 편석에 대한 연구
강관구(Kwan-Gu Kang),유홍선(Hong-Sun Ryou),허남건(Nahm-keon Hur) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
A fully coupled fluid flow, heat, and solute transport model was developed to investigate turbulent flow, solidification, and macrosegregation in a continuous casting process of steel slab with EMBR. Transport equations of mass, momentum, energy, and species for a binary iron-carbon alloy system were solved using a continuum model. The electromagnetic field was described by the Maxwell equations. A finite-volume method was employed to solve the conservation equations associated with appropriate boundary conditions. The effects of intensity of magnetic field and carbon segregation were investigated. The electromagnetic field reduces the velocity of molten flow in the mold and an increase in the percentage of C in steel results in a decrease of carbon segregation ratio.
이성혁(Seong Hyuk Lee),강관구(Kwan Gu Kang),이준식(Joon Sik Lee),최영기(Young Ki Choi),박승호(Seungho Park),유홍선(Hong Sun Ryou) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
The present article reports extensive numerical results on the non-local characteristics of ultra-short pulsed laser-induced breakdowns of fused silica (SiO2) by using the multivariate Fokker-Planck equation. The nonlocal type of multivariate Fokker-Planck equation is modeled on the basis of the Boltzmann transport formalism to describe the ultra-short pulsed laser-induced damage phenomena in the energy-position space, together with avalanche ionization, three-body recombination, and multiphoton ionization. Effects of electron avalanche, recombination, and multiphoton ionization on the electronic transport are examined. From the results, it is observed that the recombination becomes prominent and contributes to reduce substantially the rate of increase in electron number density when the electron density exceeds a certain threshold. With very intense laser irradiation, a strong absorption of laser energy takes place and an initially transparent solid is converted to a metallic state, well known as laser-induced breakdown. It is also found that full ionization is provided at intensities above threshold, all further laser energy is deposited within a thin skin depth.
펄스 레이저가 입사된 실리콘 박막내의 광학 및 열전달 특성
이성혁(Seong Hyuk Lee),강관구(Kwan Gu Kang),이준식(Joon Sik Lee),최영기(Young Ki Choi),박승호(Seungho Park),유홍선(Hong Sun Ryou) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
This study investigates conductive/radiative heat transfer characteristics in thin silicon layers irradiated by pulsed lasers. The electromagnetic theory is used to predict energy absorption in nanoscale thin films, and the wave interference effects and the changes in complex refractive index are considered during laser heating. In particular, reduced thermal conductivity in nanoscale thin film and thermal boundary resistance at interfaces are estimated by the equation of phonon radiative transfer. The optical characteristics are moreover examined by thin film optics. It is found that thin film optics and reduced thermal conductivity should be used in predicting temperature distribution in the semiconductor material as well as in developing optical diagnostic methods at the nanosecond scale.
유홍선(Hong-Sun Ryou),노경철(Kyoung Chul Ro),강관구(Kwan Gu Kang),허남건(Nahmkeon Hur) 한국전산유체공학회 2007 한국전산유체공학회 학술대회논문집 Vol.2007 No.-
NUFLEX is a general purpose program for the analysis 3D thermo/fluid flow and pre/post processor in a complex geometry. NUFLEX is composed various physical models, such as phase change(solidijlcatian/melting) and spray, MHD(Magneto Hydraulic Dynamics) models. It is possible to simulate of continuous cast iron process and spray droplet breakup/collision phenomenon. For the verification of these models, compared with the experimental data and commercial CFD code's results. The results show good agreements with experimental and comercial CFD codes's results.
노현정 ( Hyon-jeong Noh ),이호생 ( Ho-saeng Lee ),지호 ( Ho Ji ),강관구 ( Kwan-gu Kang ) 한국산업융합학회 2021 한국산업융합학회 논문집 Vol.24 No.6
Due to climate change and population growth, water scarcity is getting worse all over the world. Among various methods for desalination of seawater, the Multi-Effect Adsorptive Desalination method, which combines the existing Multi-Effect Desalination method and the Adsorptive Desalination method and can produce high-concentration-high-concentration freshwater, is emerging. Because the Multi-Effect Adsorptive Desalination method combines the two different methods, the system becomes complicated and the possibility of failure increases. Therefore, in this study, availability analysis was performed on the Multi-Effect Adsorptive Desalination process. A total of four types of reliability block diagrams were presented, and availability analysis was conducted based on them. The first form of a reliability block diagram is configured in series without any redundancy. The availability of the reliability block diagram composed of the serial system was found to be lower than the required availability. In order to increase availability, the redundancy to pumps and boiler are added to system. As a result of availability analysis, it was confirmed that designing desalination systems with redundancy to pump meets the 93% availability, which is typically required availability for various plants.