• 한국안전학회지
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• 제20권2호
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• pp.113-118
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• 2005

Recently, the corrosion of reinforced concrete structures has received great attention related with the deterioration of sea-side structures, such as new airport, bridges, and nuclear power plants. In this regards, many studies have been done on the chloride attack in concrete structures. The purpose of the present study is to explore the influences of chloride attack parameters to service life of reinforced concrete structures and to propose the rational program for the guarantee of service life. for this purpose, several codes for durability design have been examined and the diffusion analysis based on Fick's second law has been performed with various parameter value. The present study indicates that durability design code of Japan Society of Civil Engineers is more rational than other codes but the application of durability design code of JSCE to domestic durability design needs more studies to the various parameter values related with chloride penetration.

• 한국도로학회논문집
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• 제14권5호
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• pp.1-9
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• 2012

PURPOSES: A viscoelastic axisymmetric finite element analysis code has been developed for stress analysis of asphalt pavement structures. METHODS: Generalized Maxwell Model (GMM) and 4-node isoparametric element were employed for finite element formulation. The code was developed using $C^{+}^{+}$ computer program language and named as KICTPAVE. For the verification of the developed code, a structural model of a pavement system was constructed. The structural model was composed of three layers: asphalt layer, crushed stone layer, and soil subgrade. Two types of analysis were considered for the verification: (1)elastic static analysis, (2)viscoelastic time-dependent analysis. For the elastic static analysis, linear elastic material model was assigned to all the layers, and a static load was applied to the structural model. For the viscoelastic time-dependent analysis, GMM and linear elastic material model were assigned to the asphalt layer and all the other layers respectively, and a cyclic loading condition was applied to the structural model. RESULTS: The stresses and deformations from KICTPAVE were compared with those from ABAQUS. The analysis results obtained from the two codes showed good agreement in time-dependent response of the element under the loading area as well as the surface deformation of asphalt layer, and horizontal and vertical stresses along the axisymmetric axis. CONCLUSIONS: The validity of KICTPAVE was confirmed by showing the agreement of the analysis results from the two codes.

• Nuclear Engineering and Technology
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• 제44권6호
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• pp.561-586
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• 2012

This paper describes a summary of final prediction results by system-scale safety analysis codes during the OECD/NEA/CSNI ISP-50 exercise, targeting a 50% Direct Vessel Injection (DVI) line break integral effect test performed with the Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS). This ISP-50 exercise has been performed in two consecutive phases: "blind" and "open" phases. Quantitative comparisons were performed using the Fast Fourier Transform Based Method (FFTBM) to compare the overall accuracy of the collected calculations. Great user effects resulting from the combination of the possible reasons were found in the blind phase, confirming that user effect is still one of the major issues in connection with the system thermal-hydraulic code application. Open calculations showed better prediction accuracy than the blind calculations in terms of average amplitude (AA) value. A total of nineteen organizations from eleven countries participated in this ISP-50 program and eight leading thermal-hydraulic system analysis codes were used: APROS, ATHLET, CATHARE, KORSAR, MARS-KS, RELAP5/MOD3.3, TECH-M-97, and TRACE.

• Computers and Concrete
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• 제3권2_3호
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• pp.123-144
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• 2006

Reinforced concrete corbels are structural elements widely used in practical engineering. The complex response of these elements is described in design codes in a simplified manner. These formulations are not sufficient to show the real behavior, which, however, is an essential prerequisite for the manufacturing of numerous elements. Therefore, a deterministic and probabilistic study has been performed, which is described in this contribution. Real complex structures have been modeled by means of the finite element method supported primarily by experimental works. The main objective of this study was the detection of uncertainties effects and safety margins not captured by traditional codes. This aim could be fulfilled by statistical considerations applied to the investigated structures. The probabilistic study is based on advanced Monte Carlo simulation techniques and sophisticated nonlinear finite element formulations.

• 정보처리학회논문지C
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• 제15C권4호
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• pp.239-244
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• 2008

보안 침입 사건이 있은 후 해당되는 취약점만을 패치시키는 방식으로만 침입 피해를 줄이는 것은 충분하지 않다. 시스템 내에 취약한 코드가 있더라도 시스템의 내구성을 높여 보다 포괄적으로 침입을 막을 수 있는 방법이 필요하다. 본 논문은 리눅스 시스템에서 관리자를 대신하여 root 권한을 가진 프로세스를 감시하는 강건한 실시간 침입탐지기법을 제시한다. 이 기법은 사용자IP 주소를 프로세스 테이블에 추가하고 root 권한으로 기동되는 모든 프로세스의 IP 주소를 감시한다. 제안한 기법이 버퍼 오버 플로우 취약성에 대해 방어하는 것을 KON 프로그램을 통해 확인한다. 또한 원격으로 시스템을 관리할 수 있는 설정 프로토콜을 제안하며, 이 프로토콜을 통해 관리자 호스트의 IP주소가 침입으로부터 안전하게 보호될 수 있다.

• 정보보호학회논문지
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• 제18권2호
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• pp.85-96
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• 2008

실행코드의 변조와 역분석(reverse engineering)을 방지하기 위한 대표적인 방법은 실행코드를 암호화하는 것이다. 본 논문에서는 키 체인(key chaining) 방식의 블록암호화 기법을 이용하여 응용프로그램을 암호화하는 방법을 제안한다. 키체인 방식의 블록암호화 기법은 키가 블록의 내부에 은닉되어 있고 각 블록의 키가 서로 다르다는 장점을 갖지만, 제어이동을 필요로 하는 프로그램에 적용하기에는 적합하지 않다고 알려져 있다. 본 논문에서는 실행코드에서의 제어이동 명령어에 대해서도 키체인 방식을 효과적으로 적용할 수 있도록 블록을 변형시키거나 중복시키는 방법을 제시하고, MIPS 명령어집합을 이용하여 가능성을 분석한다.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.1097-1104
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• 2023

A preliminary criticality analysis for novel pyrochemical apparatuses for the reprocessing of mixed uranium-plutonium nitride spent nuclear fuel from the BREST-OD-300 reactor was performed. High-temperature processing apparatuses, "metallization" electrolyzer, refinery remelting apparatus, refining electrolyzer, and "soft" chlorination apparatus are considered in this work. Computational models of apparatuses for two neutron radiation transport codes (MCU-FR and MCNP) were developed and calculations for criticality were completed using the Monte Carlo method. The criticality analysis was performed for different loads of fissile material into the apparatuses including overloading conditions. Various emergency situations were considered, in particular, those associated with water ingress into the chamber of the refinery remelting apparatus. It was revealed that for all the considered computational models nuclear safety rules are satisfied.

• Journal of Preventive Medicine and Public Health
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• 제51권5호
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• pp.227-233
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• 2018

Objectives: Chronic diseases, including back pain, result in significant patient morbidity and societal burden. Overall improvement in physical fitness is recommended for prevention and treatment. Walking is a convenient modality for achieving initial gains. Our objective was to determine whether neighbourhood walkability, acting as a surrogate measure of physical fitness, was associated with the presence of chronic disease. Methods: We conducted a cross-sectional study of prospectively collected data from a prior randomized cohort study of 227 patients referred for tertiary assessment of chronic back pain in Ottawa, ON, Canada. The Charlson Comorbidity Index (CCI) was calculated from patient-completed questionnaires and medical record review. Using patients' postal codes, neighbourhood walkability was determined using the Walk Score, which awards points based on the distance to the closest amenities, yielding a score from 0 to 100 (0-50: car-dependent; 50-100: walkable). Results: Based on the Walk Score, 134 patients lived in car-dependent neighborhoods and 93 lived in walkable neighborhoods. A multivariate logistic regression model, adjusted for age, gender, rural postal code, body mass index, smoking, median household income, percent employment, pain, and disability, demonstrated an adjusted odds ratio of 2.75 (95% confidence interval, 1.16 to 6.53) times higher prevalence for having a chronic disease for patients living in a car-dependent neighborhood. There was also a significant dose-related association (p=0.01; Mantel-Haenszel chi-square=6.4) between living in car-dependent neighbourhoods and more severe CCI scores. Conclusions: Our findings suggest that advocating for improved neighbourhood planning to permit greater walkability may help offset the burden of chronic disease.

• 한국컴퓨터정보학회논문지
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• 제16권6호
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• pp.41-50
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• 2011

악의적인 소프트웨어 역공학으로부터 프로그램이 가지는 코드를 보호하기 위해서 코드 난독화가 제안되었다. 이것은 기존에 존재하는 프로그램 코드를 어렵게 변환시키는 것으로 프로그램 코드에 대한 악의적인 정적 분석을 어렵게 만든다. 코드 난독화는 난독화 목적에 따라 레이아웃, 데이터, 제어 난독화로 분류되어진다. 이 중 제어 난독화는 프로그램이 가지는 제어 흐름에 대한 추상적인 정보를 보호하는 것으로 다양한 종류의 개별 제어 흐름 난독화 변환이 제안되었지만, 이를 효과적으로 적용할 수 있는 방법은 제안되지 않았다. 본 논문에서는 제어 흐름 난독화 변환을 프로그램에 효과적으로 적용할 수 있는 난독화 전략을 제안하고, 실험을 통해서 제안한 난독화 전략의 효용을 보였다.

• 정보처리학회논문지A
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• 제16A권6호
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• pp.453-462
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• 2009

소프트웨어의 지적 재산권 보호 및 인증에 대한 관심과 중요성이 커지면서 소프트웨어에 대한 표절 탐색 및 보호, 판단에 대한 연구가 활발 하게 진행되고 있다. 지금까지 표절에 대한 연구는 주로 속성 계산, 토큰 패턴, 프로그램 파스트리, 유사도 측정 알고리즘 등을 이용해 두 프로 그램을 비교하는데 초점을 두었다. 이와 더불어, 표절과 협동(collaboration)을 구분하는 것은 표절연구에서 매우 중요하다. 본 논문에서는 극단 치 분포 확률 모델을 이용한 소스코드 클러스터링을 위한 알고리즘을 제안한다. 본 논문에서는 먼저 두 프로그램 먼저 두 프로그램 $P_a$와 $P_b$ 의 유사도를 측정하는 비대칭거리측정함수 pdist($P_a$, $P_b$)를 제안하고, 모든 소스코드 쌍에 대해 pdist($P_a$, $P_b$)를 통해 측정된 유사도를 간선무게로 하는 표절방 향그래프(PDG)를 생성한다. 그리고 본 논문에서는 표절방향그래프를 굼벨거리그래프(GDG)로 변환한다. pdist($P_a$, $P_b$) 점수 분포는 극단치 확률 분포로 잘 알려진 굼벨분포(Gumbel distribution)와 매우 유사하다. 또한, 본 논문에서는 의사표절(pseudo- plagiarism)을 새롭게 정의한다. 의사표절은 프로그램의 강한 기능적 제약사항으로 인해 발생하는 가상 표절의 한 종류이다. 본 논문에서는 ICPC(International Collegiate Programming Contest)와 KOI(Korean Olympiad for Informatics) 대회에 제출된 18개 프로그램 그룹의 700개 이상의 소스코드에 대해 실험을 진행하였다. 실험결과 프로그램 그룹에 포함된 표절 프로그램들을 찾았으며, 소스코드 클러스터링 알고리즘은 의사표절과 실제표절 프로그램 그룹을 효과적으로 구분하였다.