• 한국결정성장학회지
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• 제11권6호
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• pp.259-263
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• 2001

The continuum model of transient point defect dynamics to predict the concentrations of interstitial and vacancy is established by estimating expressions for the thermophysical properties of intrinsic point defects. And the point defect distribution in a Czochralski-grown 200 mm silicon crystal and the location of oxidation-induced stacking fault ring(OiSF-ring) created during the cooling of crystals are calculated by using the numerical analysis. The purpose of this paper is to show that his approach lead to predictions that are consistent with experimental results. Predicted point defect distributions by transient point defect dynamic analysis are in good qualitative agreement with experimental data under widely and abruptly varying crystal pull rates when correlated with the position of the OiSF-ring .

• 전자공학회논문지D
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• 제34D권5호
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• pp.32-44
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• 1997

A three-dimensional (3D) full-dynamic damage model for ion implantation in crystalline silicon was proposed to calculate more accurately point defect distributions and ion-implanted concentration profiles during ion implantation process. The developed model was based on the physical monte carlo approach. This model was applied to simulate B and BF2 implantation. We compared our results for damage distributions with those of the analytical kinchin-pease approach. In our result, the point defect distributions obtained by our new model are less than those of kinchin-pease approach, and the vacancy distributions differ from the interstitial distributions. The vacancy concentrations are higher than the interstitial ones before 0.8 . Rp to the silicon surface, and after the 0.8 . Rp to the silicon bulk, the interstitial concentrations are revesrsely higher than the vacancy ones.The fully-dynamic damage model for the accumulative damage during ion implantation follows all of the trajectories of both ions and recoiled silicons and, concurrently, the cumulative damage effect on the ions and the recoiled silicons are considered dynamically by introducing the distributon probability of the point defect. In addition, the self-annealing effect of the vacancy-interstitial recombination during ion implantation at room temperature is considered, which resulted in the saturation level for the damage distribution.

• Nuclear Engineering and Technology
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• 제36권3호
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• pp.229-236
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• 2004

Radiation hardening is a multiscale phenomenon involving various processes over a wide range of time and length. We present a multiscale model for estimating the amount of radiation hardening in pressure vessel steel in the environment of a light water reactor. The model comprises two main parts: molecular dynamics (MD) simulation and a point defect cluster (PDC) model. The MD simulation was used to investigate the primary damage caused by displacement cascades. The PDC model mathematically formulates interactions between point defects and their clusters, which explains the evolution of microstructures. We then used a dislocation barrier model to calculate the hardening due to the PDCs. The key input for this multiscale model is a neutron spectrum at the inner surface of reactor pressure vessel steel of the Younggwang Nuclear Power Plant No.5. A combined calculation from the MD simulation and the PDC model provides a convenient tool for estimating the amount of radiation hardening.

• 정보처리학회논문지D
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• 제15D권3호
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• pp.313-320
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• 2008

전형적인 소프트웨어 생명주기 모델은 결점이 추가되거나 제거되는 단계들의 일련의 순서로 구성되어 있다. 우리가 원하는 수준의 품질을 달성하기 위해서는 소프트웨어 개발 전 과정에서 결점 제거를 수행하여야 한다. 잘 알려진 단계기반 결점 프로파일은 Gaffney 모델이 있다. 이 모델은 결점 제거 프로파일이 Rayleigh 분포를 따르며 단계 인덱스 번호를 모수로 하고 있다. 실제 개발되는 소프트웨어에 Gaffney 모델을 적용시 제거된 결점이 최대값이 되는 점을 위치 모수가 표현하지 못하는 문제가 있다. 그러므로 Gaffney 모델은 실제 결점 프로파일을 표현하지 못한다. 본 논문은 2개의 다른 모델을 제시한다. 하나는 수정된 Gaffney 모델로 위치 모수를 교체하기 위해 Putnam의 SLIM 모델의 모수를 도입하였다. 다른 하나는 누적 결점 프로파일이 S자 형태를 보여 성장곡선 모델을 제시하였다. 제안된 모델은 5개의 다른 소프트웨어 프로젝트로부터 얻어진 결점 프로파일 분석에 의해 검증하였다. 실험 결과 제안된 모델이 Gaffney 모델 보다 좋은 결과를 얻었다.

• 대한기계학회논문집A
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• 제29권2호
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• pp.253-261
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• 2005

In decades, a substantial body of work on a unified viscoplastic model which considers the mechanism of plastic deformation and creep deformation has developed. The systematic scheme for numerical analysis of unified model is necessary because the dominant failure mechanism is the defect growth and coalescence in materials. In the present study, the unified viscoplastic model for materials with defects suggested by Suquet and Michel was employed for numerical analysis. The constitutive equations are integrated based on the generalized mid-point rule and implemented into a finite element program (ABAQUS) by means of user-defined subroutine (UMAT). To evaluate the validity of the developed UMAT code and the assessment of the adopted viscoplastic model, the results obtained from the UMAT code was compared with the numerical reference solution and experimental data. The unit cell analysis also has been investigated to study the effect of strain rate, temperature, stress triaxiality and initial defect volume fraction on the growth and coalescence of the defect.

• 한국건설관리학회논문집
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• 제20권4호
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• pp.13-21
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• 2019

본 연구의 목적은 거주자가 하자정보를 정확하게 입력하고 건설회사와 정보를 공유 할 수 있는 하자정보 관리시스템에 대한 개선모델을 제시하는 것이다. 이를 위하여 기존의 하자정보 관리시스템을 고찰하고 거주자가 요구하는 기능을 적용하여 개선모델의 구조와 데이터 흐름 계통도를 제시하였다. 그리고 개선모델의 경제적 효과를 추정하였다. 상기와 같은 목적과 방법에 따라 도출된 결과는 다음과 같다. 빅 데이터와 연계하기 위한 하자정보 관리시스템의 정보입력화면에 대한 기본설계를 하였다. 또한 개선 모델을 활용함에 따라 유발되는 경제적 효과는 기존 방법 대비 약 151백만원이 절감되는 것으로 추정되었다.

• Journal of Korean Vacuum Science & Technology
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• 제3권1호
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• pp.1-9
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• 1999

This paper presents a newly enhanced damage model in Monte Carlo (MC) simulation for the accurate prediction of 3-Dimensional (3D) as-implanted impurity and point defect profiles induced by ion implantation in (100) crystal silicon. An empirical electronic energy loss model for B, BF2, As, P and Si self implant over the wide energy range has been proposed for the ULSI device technology and development. Our model shows very good agreement with the SIMS data over the wide energy range. In the damage accumulation, we considered the self-annealing effects by introducing our proposed non-linear recomvination probability function of each point defect for the computational efficiency. For the damage profiles, we compared the published RBS/channeling data with our results of phosphorus implants. Our damage model shows very reasonable agreement with the experiments for phosphorus implants.

• Corrosion Science and Technology
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• 제14권6호
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• pp.253-260
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• 2015

The pitting behaviours of 304L and 316L stainless steels were investigated at $3^{\circ}C$ to $90^{\circ}C$ in 1 M solutions of NaCl, NaBr and NaI by potentiodynamic polarization. The temperature dependences of the pitting potential varied according to the anion, being near linear in bromide but exponential in chloride. As a result, at low temperatures grades 304L and 316L steel are most susceptible to pitting by bromide ions, while at high temperatures both stainless steels were more susceptible to pitting by small chloride anions than the larger bromide and iodide. Thus, increasing temperature appears to favour attack by smaller anions. This paper will attempt to rationalise both of the above findings in terms of the point defect model. Initial findings are that qualitatively this approach can be reasonably successful, but not at the quantitative level, possibly due to insufficient data on the mechanical properties of thin passive films.

• 대한화학회지
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• 제54권4호
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• pp.380-386
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• 2010

황산 용액에서 양극산화(anodization)에 의하여 생성되는 산화피막의 생성과정(growth kinetics)과 이 피막의 전기적 성질을 전기화학적 임피던스 측정법(electrochemical impedance spectroscopy)으로 조사하였다. 산화피막은 $Al_2O_3$로 점-결함 모형(point defect model)에 따라 성장하였으며, n-형 반도체의 전기적 성질을 보였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.421-424
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• 1998

In this paper are presented a newly proposed 3D monte carlo (MC) damage model for the dynamic simulation in order to more accurately and consistently predict the implant-induced point defect distributions of the various ions in crystalline silicon. This model was applied to phosphorus implants for the ULSI CMOS technology developement. In additon, a newly applied 3D-trajectory split method has been implemented into our model to reduce the statistical fluctuations of the implanted impurity and the defect profiles in the relatively large implanted area as compared to 1D or 2D simulations. Also, an empirical electronic energy loss model is proposed for phosphorus and silicon implants. The 3D formations of the amorphous region and the ultra-shallow junction around the implanted region could be predicted by using our model, TRICSI(Transport ions into crystal-silicon).