• Bulletin of the Korean Chemical Society
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• 제15권2호
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• pp.139-145
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• 1994

The DOS, COOP and O 1s binding energy are calculated for Ni24(100) model surface with oxygen adsorbed on it. The calculation is made with PC/386 using the program obtained by converting EHMACC(VAX version) into PC version. The calculation shows the dissociative adsorption of oxygen molecule, of which the main cause is attributed to the transfer of the $d{\pi}$ and $d{\delta}$ electrons of Ni to the antibonding $1{\pi}_g$ of oxygen molecule. The O ls shift on the adsorption is calculated using the valence potential method, and the results agree fairly good with the experimental values.

• Bulletin of the Korean Chemical Society
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• 제15권12호
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• pp.1093-1097
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• 1994

The interaction of oxygen molecule with Ni44(111) model surface to which the molecule approaches is studied by calculating the relevant DOS and COOP with the tight-binding EHT method. It is found that the dissociative adsorption of oxygen takes place as a result of electron transfer from the Ni d${\pi}$ orbital to the antibonding 1${\pi}_g$ orbital of the oxygen molecule. This finding is noteworthy to contrast with the case of Ni(100) surface in which the electron transfer takes place from the Ni d${\delta}$ orbital of the nickel surface.

• Coupled systems mechanics
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• 제8권2호
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• pp.147-168
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• 2019

This work aims to simulate three-dimensional heavy oil flow in a reservoir with heater-wells. Mass, momentum and energy balances, as well as correlations for rock and fluid properties, are used to obtain non-linear partial differential equations for the fluid pressure and temperature, and for the rock temperature. Heat transfer is simulated using a two-equation model that is more appropriate when fluid and rock have very different thermal properties, and we also perform comparisons between one- and two-equation models. The governing equations are discretized using the Finite Volume Method. For the numerical solution, we apply a linearization and an operator splitting. As a consequence, three algebraic subsystems of linearized equations are solved using the Conjugate Gradient Method. The results obtained show the suitability of the numerical method and the technical feasibility of heating the reservoir with static equipment.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2002년도 학술발표회 발표논문집
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• pp.381-384
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• 2002

The purpose of this study is to construct an Environment Database Management System (EDMS) for the Saemangeum watershed based on the linkage of Water Quality Model, i.e. QUALKO and WASP model, and GIS database to estimate water quality effectively in this area. There are two major river systems on this study area, the Mangyeong and the Dongjin rivers. Input data are automatically generated through the calculation of the pollutant loading and inflow concentration from the point and non-point sources. The developed system is composed of three different phases, such as pre-process, model performance and post-process. The Model performance is supported by the database at pre-process phase and model performance results were shown in the graphs and attribution data at post-process phase. The measured data from the Mangyeong and the Dongjin rivers are used to evaluate the applicability of EDMS. The EDMS shows higher reliability, and it is expected to contribute to the effective management and improvement of water quality modeling in the Saemangeum watershed since the system reduces complications of using a model in DOS operating environment and increases the accuracy of water quality analysis.

• Radiation Oncology Journal
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• 제8권2호
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• pp.151-154
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• 1990

영남대학교 의과대학 치료방사선과학교실에서는 코발트-60원격치료기를 이용하여 80마리의 ICR 백서를 대상으로 서로다른 세가지 선량율로 600 cGy 단일조사를 시행한뒤 9주일동안 체중 및 말초혈액소견의 변화를 추적조사한 결과 다음과 같은 성적을 얻었다. 1. 체중변화는 선량율에 상관없이 조사 1주일부터 감소하여 6-7주일부터 치료전의 체중까지 회복 되었다. 2. 혈색소의 변화는 전 추적조사기간에 걸쳐 변화가 없었다. 3. 말초 혈액내의 백혈구의 총수는 조사 1주일부터 3주일까지 형태학적 구분이 안되는 수개의 세포만이 인지되었고 4주일부터 호중구의 회복이 임파구에 비해서 현저하였으며 8-9주일부터 조사전의 상태로 완전 회복되었다. 이상의 결과를 토대로 보다 다양한 실험을 거친후 저선량율 전신조사의 가장 큰 단점인 장시간의 조사로 인한 기계의 무리와 환자 위치고정의 해결을 위하여 분당 선량율을 15 cGy까지 올릴 수 있으리라 기대된다.

• Imaging Science in Dentistry
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• 제43권1호
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• pp.1-6
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• 2013

Purpose: This study investigated the possible correlation between the mineralization of the second molars and the chronological age of a sample population of the state of Paraiba, Brazil. Materials and Methods: One thousand eight hundred fifty-four digitized panoramic images using a scanner of a private dental radiology service were obtained in six months. Of these, 457 were selected from patients aged 4.6 to 16 years who met certain criteria. The images were assessed twice by a radiologist with 5 years experience. A minimum interval of 30 days between the evaluations of the same patient was established. To analyze the relationship between chronological age, calcification level proposed by Demirjian et al in 1973, gender, and tooth, a multiple linear regression model was adjusted, taking age as the response variable (p<0.05). Results: The gender and calcification level were significantly correlated with the age of the patients (p<0.05). There was a significant difference between the average age of the patients' upper teeth compared to the lower ones in both genders (p<0.05). The dental development occurred earlier in female individuals than in male ones, and there was no significant difference between the right and left second permanent molars. Conclusion: It was observed that ethnic variables are related to certain parameters of age and sex identification in the Brazilian population, providing important information for forensic evaluations.

• Nuclear Engineering and Technology
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• 제52권4호
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• pp.819-826
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• 2020

The method of the Laplace transform has been used to obtain an analytical solution of the three-dimensional steady state advection diffusion equation for the airborne radionuclide release from any nuclear installation such as the power reactor in an area source. The present treatment takes into account the removal of the pollutants through the nuclear reaction. We assume that the pollutants are emitted as a constant rate from the area source. This physical consideration is achieved by assuming that the vertical eddy diffusivity coefficient should be a constant. The prevailing wind speed is a constant in 𝑥- direction and a linear function of the vertical height z. The present model calculations are compared with the other models and the available data of the atmospheric dispersion experiments that were carried out in the nuclear power plant of Angra dos Reis (Brazil). The results show that the present treatment performs well as the analytical dispersion model and there is a good agreement between the values computed by our model and the observed data.

• Wind and Structures
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• 제15권2호
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• pp.111-129
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• 2012

Codes for structural design usually assume that the incident mean wind velocity is parallel to the ground, which constitutes a valid simplification for frequent winds caused by sypnoptic events. Wind effects due to other phenomena, such as thunderstorm downbursts, are simply neglected. In this paper, results of recent and ongoing research on this topic in Brazil are presented. The model of the three-dimensional wind velocity field originated from a downburst in a thunderstorm (TS), proposed by Ponte and Riera for engineering applications, is first described. This model allows the generation of a spatially and temporally variable velocity field, which also includes a fluctuating component of the velocity. All parameters are related to meteorological variables, which are susceptible of statistical assessment. An application of the model in the simulation of the wind climate in a region sujected to both EPS and TS winds is discussed next. It is shown that, once the relevant meteorological variables are known, the simulation of the wind excitation for purposes of design of transmission lines, long-span crossings and similar structures is feasible. Complementing the theoretical studies, wind velocity records during a recent TS event in southern Brazil are presented and preliminary conclusions on the validity of the proposed models discussed.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.451-454
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• 2011

The traditional BCS superconductors $AOs_2O_6$ (A=K, Rb, and Cs) were investigated to find the relationship between their structures and superconducting transition temperatures. The $T_c$ decreases with increasing the unit cell parameter of $AOs_2O_6$. This is in contrast to the case of conventional BCS superconductivity in a single bond model, where $T_c$ may increase with increasing the the unit cell parameter since the DOS at Fermi level increases as the unit cell parameter increases. Instead, the $T_c$ of a $\beta$-pyrochlore oxide is proportional to the lattice softness of the compound.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2004년도 봄 학술발표논문집 Vol.31 No.1 (A)
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• pp.301-303
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• 2004

인터넷의 급성장으로 해킹이나 Dos 공격, 웜, 바이러스 등의 사이버 범죄가 크게 증가하고 지능화되어 최근 역추적에 대한 관심이 날로 증가하고 있다. 보안 도구로 침입탐지시스템(IDS) 이나 침입방지시스템 (IPS) 등이 있으나 해킹이나 DoS 공격을 방어하는데 현실적으로 한계가 있다. 따라서 능동적인 해킹 방어를 위한 기본적인 기술로 해커의 실제 위치를 추적하는 역추적 시스템 기술이 필요하다. 특히 IPv4에서의 역추적 시스템에 대한 연구는 활발하게 이루어지고 있지만 IPv6에 대한 연구는 아직 미흡하다. 본 논문에서는 IPv4의 주소 고갈로 인해 앞으로 이를 대신할 IPv6에 대한 공격 근원지 역추적 시스템 개발이 시급하다고 보고. 해킹을 시도하는 해커의 실제 위치를 실시간으로 추적할 수 있도록 IPv6 헤더 패킷의 트래픽 클래스(Traffic Class)와 플로우 라벨(Flow Label)을 이용하여 IPv6에서의 실시간 네트워크 침입자 역추적 시스템 모델을 제안하고자 한다.