• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1996년도 The 9th KACG Technical Annual Meeting and the 3rd Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.139-156
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• 1996

The phase field model is becoming the model of choice for the theoretical study of the morphologies of crystals growth from the melt. This model provides an alternative approach to the solution of the classical (sharp interface) model of solidification by introducing a new variable, the phase field, Ø, to identify the phase. The variable Ø takes on constant values in the bulk phases and makes a continuous transition between these values over a thin transition layer that plays the role of the classically sharp interface. This results in Ø being governed by a new partial differential equation(in addition to the PDE's that govern the classical fields, such as temperature and composition) that guarantees (in the asymptotic limit of a suitably thin transition layer) that the appropriate boundary conditions at the crystal-melt interface are satisfied. Thus, one can proceed to solve coupled PDE's without the necessity of explicitly tracking the interface (free boundary) that would be necessary to solve the classical (sharp interface) model. Recent advances in supercomputing and algorithms now enable generation of interesting and valuable results that display most of the fundamental solidification phenomena and processes that are observed experimentally. These include morphological instability, solute trapping, cellular growth, dendritic growth (with anisotropic sidebranching, tip splitting, and coupling to periodic forcing), coarsening, recalescence, eutectic growth, faceting, and texture development. This talk will focus on the fundamental basis of the phase field model in terms of irreversible thermodynamics as well as it computational limitations and prognosis for future improvement. This work is supported by the National Science Foundation under grant DMR 9211276

• 한국분말재료학회지
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• 제18권2호
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• pp.168-171
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• 2011

We investigate grain growth behavior of poly-crystalline Mg sheet having strong basal fiber texture using phase field model for grain growth and micro-elasticity. Strong initial basal texture was maintained when external load was not imposed, but was weaken when external biaxial strain was imposed. Elastic interaction between elastic anisotropy of Mg grain and external load is the reason why texture evolution occurs.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권5호
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• pp.382-385
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• 2000

A mathematical model was developed, based on the time dependent changes of the specific growth rate, for prediction of the typical microbial cell growth in batch cultures. This model could predict both the lag growth phase and the stationary growth phase of batch cultures, and it was tested with the batch growth of Trichoderma reesei and Lactobacillus delbrueckii.

• 한국결정성장학회지
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• 제5권3호
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• pp.291-298
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• 1995

알루미나 고상소결체와 $CaMgSiO_4$간의 반응에 따른 반응상들의 성장 및 용해 거동을 $1600^{\circ}C$에서 열처리 시간을 변화하여 고찰하였다. 열처리시 알루미나는 $CaMgSiO_4$ 액상에 용융되어 중간에 반응상인 $CaO{\cdot}6Al_2O_3$와 최종 반응상인 $CaMgSiO_4$ 스피넬 형성이 관찰되었다. 중간상인$CaO{\cdot}6Al_2O_3$ 결정은 성장 모양과 용해 모양이 뚜렷하게 구분되었다.

• 대한기계학회논문집
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• 제17권7호
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• pp.1700-1709
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• 1993

The stepped specimen which is subjected to step loading is modeled to study the initiation and growth of adiabatic shear band using explicit time integration finite element method. Three different clearance sizes are tested. The material model for the stepped specimen includes effects of strain hardening, strain rate hardening and thermal softening. It is found that the material inside the fully grown adiabatic shear band experiences three phase of deformation, (1) homogeneous deformation phase, (2) initiation/incubation phase, and (3) fast growth phase. The second phase of deformation is initiated after sudden shear stress drop which occurs at the same time regardless of the clearance size. The incubation time prior to fast growth phase increases, as the clearance size of the stepped specimen increases. Whereas, after incubation period, the growth rate of the adiabatic shear band decreases, as the clearance size decreases. It is also found that two adiabatic shear band may develop instead of one for the smaller clearance size.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.533-538
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• 2000

Ductile fracture of dual phase steel begins with void nucleation, at martensite-ferrite interface of deformed martensite particle. In this study, void nucleation, growth, and coalescence under various strain were studied in dual phase steel. Therefore, by means of the heat treatment of low carbon steel, the study deals with void nucleation and growth for ferrite grain size and martensite volume fraction of dual phase steel using statistical method. Void nucleation and growth with increasing strain are shown depend upon the ferrite grain size. Voids volume fraction generally increase as ferrite grain size decease.

• Agricultural and Biosystems Engineering
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• 제7권1호
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• pp.42-47
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• 2006

The objective of this study was to investigate the effects of air-phase germination with water-spraying and anion stimuli on germination ratio, sprout growth and ${\gamma}$-aminobutyric acid (GABA) of brown rice. Air-phase germination method with intermittent spraying water improved germination ratio and sprout growth by about 100% compared with the conventional water-soaking method. Anion radiation was applied during the germination process and improved the germination ratio, sprout growth and color quality of the germinated brown rice. Germination ratio and sprout growth were improved up to 9% with anion radiation, and its brightness was higher than brown rice germinated with no anion radiation. The air-phase germination with water-spraying improved the GABA content of germinated brown rice by about 8-9 times compared with that of brown rice.

• Journal of Microbiology and Biotechnology
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• 제16권12호
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• pp.1856-1861
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• 2006

A Bacillus sp. A-6 strain that produced xylanase was isolated from rice bran. The optimal temperature and pH for xylanase activity of the culture supernatant of Bacillus sp. A-6 were 40$^{\circ}C$ and pH 7, respectively. The optimal temperature and pH for xylanase production in the xylan medium were 30$^{\circ}C$ and pH 9, respectively. The optimal concentrations of oat spelt xylan and peptone for xylanase production were 0.5% and 1.5%, respectively. The best nitrogen sources for xylanase production was beef extract, but xylanase production was also supported comparably by tryptone and peptone. The bacterial growth in the optimal xylan medium reached stationary growth phase after 12 h of incubation. The xylanase production in the culture supernatant increased dramatically during the initial 12 h exponential growth phase and then remained constant at 23.8-24.5 unit/ml during the stationary growth phase. The pH of the culture medium decreased from 8.8 to 6.7 during the exponential growth phase and subsequently increased to 8.1 during the stationary growth phase. Rice bran, sorghum bran, and wheat bran as well as oat spelt xylan induced xylanase production. The xylanase production was repressed when glucose was added to the xylan-containing medium.

• 대한전자공학회논문지
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• 제23권6호
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• pp.820-832
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• 1986

In contrast to conventional liquid phase epitaxy of GaAs, surface kinetics limited growth is predominant in selective liquid phase epitaxy. For the stripe openings in the high-index crystal-lographic directions, the well-known facet formations and the decompositions into the low index planes or smooth circular surfaces are observed depending on the growth kinetics. For the low index direction stripe, surface kinetics limited growth is evident. By a numerical calcualtion we show that these phenomena are due to the enhanced masstransport by two dimensional diffusion and growth rate anisotropy which is found to be very stdrong with cusped minima for some singular planes in the solution growth as well as in vapor phase epitaxy. Morphological stability is briefly treated in terms of diffusion and its implications on device application are stated. Tese phenomena may be common to III-V compound semiconductors as well as GaAs.

• Radiation Oncology Journal
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• 제17권3호
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• pp.223-229
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• 1999

목적 : 세포의 성장 상태 즉, 지수적 증식기와 평형기 세포에서 방사선에 의한 c-jun의 발현 양상의 차이를 파악하고, 방사선조사 후 세포주기 분포를 분석하여 이들의 상관 관계를 알아보고자 하였다. 대상 및 방법 : 사람 자궁경부암 세포주인 CaSki를 대상으로 날자 경과에 따른 세포성장곡선을 작성하여 지수적 증식기(제 4일)와 평형기(제 9일) 세포를 정하였다. 방사선조사는 6 MV 선형가속기를 이용해 2 Gy의 선량을 조사하였고, 이때 선량률은 3 Gy/min 이었다. 지수적 증식기와 평형기 세포 각각에 방사선조사 후 시간 경과에 따라 total RNA를 추출하여 northern blot analysis를 시행해 c-jun의 발현 양상을 관찰하였다. 또 방사선조사 후 시간 경과에 따라 세포를 얻어 유세포계측법을 이용해 세포주기 분포를 분석하였다. 결과 : 방사선조사 1 시간 후에 지수적 증식기와 평형기 세포 모두에서 최대의 발현이 관찰되었다. 그러나 이후 6시간까지 지수적 증식기 세포에서는 지속적으로 발현이 증가한 반면, 평형기에서는 점차 발현이 감소되는 양상을 보였다. 방사선에 의한 세포주기의 변화는 지수적 증식기에서 시간 경과에 따라 G0-G1에서 S, G2-M 기로의 이동이 더 활발히 일어났다. 결론 : c-jun 은 방사선조사 후 성장상태에 따른 세포 증식의 조절과 관련 있을 것이다.