• 한국수소및신에너지학회논문집
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• 제21권3호
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• pp.220-226
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• 2010

The heat transfer performance improvement in closed cooling water system of an electric power generation can be achieved by a corrosion control using corrosion inhibitors. The effect of trisodium phosphate and sodium nitrite upon carbon steel at various $Cl^{-1}$ ion containing water concentrations was examined by an integrated corrosion monitoring system. Nitrite was found to be the most effective inhibitor among tested inhibitors for carbon steel. The inhibiting process is considered as adsorption of nitrite ions in oxide layer which form a passive film on the carbon steel surface.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2003년도 추계학술대회 및 정기총회
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• pp.139-144
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• 2003

Mobile Node has to maintain communication as they move form place to place, so it doesn't guarantee Quality of Service(QoS). Fast Handoff is important to provide multimedia and real-time applications services in mobile, and it is closely related to handoff delay. Therefore, handoff delay problem is actively studied to quarantee QoS as a main issue in mobile IP research area. Next generation Mobile IPv6 resolve this problem somewhat, triangle problem for first packet and handoff delay still remain. In this paper, we suggest SNMP Information-based routing that adds keyword management method to Information-based routing in active network in order to resolve such a problem, and then suggest QoS controlled handoff based on SNMP Information-Based routing. After modeling of suggested method and existing handoff method, simulations are carried out with NS-2 for performance evaluation. The results of simulations show the some improvement on handoff delay, and therefore on QoS improvement.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.847-849
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• 1998

In this paper, we propose the generalized on-line economic dispatch algorithm including transmission loss. it was derived from the process developing matrix form of the classic ELD problem. it can rapidly calculate generation power using transmission loss and transmission loss sensitivity calculated from the result of power flow analysis. Transmission loss sensitivity ${\partial}P_{loss}/{\partial}P_G$ is derived using optimization technique.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1674-1685
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• 2022

The ball valve is an important device in the pipeline transportation system of nuclear power plants. Its operational stability and safety directly affect the normal working of nuclear power plants. In this study, the transient numerical simulation of the opening and closing process of a ball valve was conducted on the basis of the flow interruption capability experiment of the ball valve by using the moving mesh method and inlet and outlet variable boundary conditions. The flow rate and pressure difference with time of the opening and closing process of the ball valve were studied. The internal flow characteristics of the ball valve under different relative openings were analyzed in conjunction with the typical back-step flow structure. Results show that the transient numerical results agree well with the experimental results. The internal flow characteristics of the ball valve are similar at the same opening during opening and closing process. At small opening, the spool and outlet channels easily form a back-step flow structure. The disappearance and generation of backflow vortices during opening and closing occur at 85% opening and 75% opening, respectively. With the decrease in opening degree, the difference in vortex core area in the flow channel of the ball valve spool in the opening and closing process gradually appears. The research results provide some reference value for the design and optimization of ball valves.

• 한국정보통신학회논문지
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• 제24권2호
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• pp.244-251
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• 2020

본 논문에서는 UML 다이어그램의 정보를 구문적으로 분석하여 클래스들의 정보를 구조적으로 구축하는 정보 저장소인 '메타 클래스 레포지토리 (MCR)'의 구현 방법을 제시한다. 구문적으로 분석된 클래스의 정보를 구조적으로 구축하기 위하여 수퍼 클래스인 '메타 클래스 (meta-class)'를 정의하고, 이들 메타 클래스들의 컬렉션으로 구성된 레포지토리를 구축하여 정보를 관리한다. 또한, MCR이 보유하고 있는 메타 클래스 정보에 기반하여 클래스에 상응하는 코드를 생성하기 위하여 '코드 생성 엔진 (CGE)'을 설계하여 제시한다. 코드 생성 엔진의 로직을 구성함에 있어서는 클래스에 대한 정보와 프로그래밍 언어의 구문 규칙이 합법적으로 조합되어 코드가 생성되어야 한다. 따라서, 이러한 클래스 다이어그램으로부터 코드를 생성하는 데에 MCR과 CGE가 통합적으로 협력하여 수행될 수 있도록 구현하는 방법을 제시한다. CGR의 동작 메커니즘에 대한 알고리즘을 유한 상태 머신 형태로 제시함으로써 CGE의 로직을 형식화하여 표현함과 동시에 구현 상의 용이함을 취할 수 있게 하였다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제31권10호
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• pp.1304-1319
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• 2004

프로그램 시험 비용은 테스트 데이타를 생성하는 과정을 자동화함으로써 상당히 줄일 수 있다. 테스트 데이타 생성은 보통 선택된 프로그램 경로를 실행하는 입력 값들을 식별하는 데 주안점을 둔다. 지금까지 많은 연구가 있어왔지만 여전히 해결해야할 문제가 있다 그러한 문제들 중에 모양 문제가 있다. 모양 문제는 주어진 프로그램 경로를 수행하기 위해 요구되는 입력 자료구조를 밝혀내는 문제이다. 이 논문에서 이 모양 문제에 대한 새로운 방법을 제시한다. 이 방법은 주어진 경로를 포인터 역 참조가 없는 정적단일 할당문 (Static Single Assignment, SSA) 형태로 변환한다. 이는 주어진 경로 상에 존재하는 각 프로그램 문장을 등식이나 부등식과 같은 제약식으로 간주할 수 있게 해준다. 이러한 제약식에 대한 해는 각 입력 변수에 대한 'points-to relation' 형태로 나타난다. 간단한 예들을 통하여 제안한 방법에 대해 설명한다.에 대해 설명한다.

• 한국정밀공학회지
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• 제32권6호
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• pp.509-515
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• 2015

Recent trends to reduce the size of mobile electronics products have driven miniaturization of various components, including screw parts for assembling components. Considering that the size reduction of screws may degenerate their joining capabilities, the size reduction should not be limited to the thread region but should be extended to its head region. The screw head is usually manufactured by forging in which a profiled punch presses a billet so that plastic deformation occurs to form the desired shape. In this study, finite element (FE) analysis was performed to simulate the forging process of a subminiature screw; a screw head of 1.7 mm diameter is formed out of a 0.82 mm diameter billet. The FE analysis result indicates that this severe forging condition leads to a generation of folding defects. FE analyses were further performed to find appropriate punch design parameters that minimize the amount of folding defects.

• 한국기계가공학회지
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• 제20권4호
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• pp.31-38
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• 2021

In this paper, we proposed an optimal design for determining the shape of a lifting lug freely by applying a multivariate function to the D-type lug, which is commonly used in shipyards. We derived the optimal aspect ratio of the lug through structural analysis and analyzed the safety and behavior of the lug aspect ratio. As a result, two types of final candidates, both lighter than the existing lug weight, were suitable for the ratio. They were found to have the greatest force at an angle of 45 degrees when a load of 100 tons was imposed. When the horizontal and vertical feature ratio of the lug was 1:3, it showed excellent results in terms of safety rates while maintaining weight reduction and functional aspects.

• 정보보호학회논문지
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• 제22권2호
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• pp.347-355
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• 2012

바이오 보안토큰은 바이오 인식 센서와 바이오인식 정보를 처리할 수 있는 MCU, 보안토큰으로 구성된 USB 형태의 하드웨어 기기로서, 기기 내부에서 바이오인식 센서로 가입자의 바이오인식 정보를 추출하여 보안토큰에 안전하게 저장하며, 사용자 인증시 바이오인식 센서로 부터 취득된 바이오인식 정보와 저장되어 있는 바이오인식 정보를 기기내부 MCU에서 매칭하여 사용자를 인증하는 독립된 하드웨어 보안모듈이다. 기존의 보안토큰이 제공하는 개인인증기법이 ID/패스워드에 기반한 방법이므로 이의 유출로 인해 생길 수 있는 피해를 최소화하고, 고의적인 공인인증서의 오용을 막을 수 있도록 높은 수준의 사용자인증기법을 제공한다. 이에 본 논문에서는 공개키기반구조(PKI: Public Key Infrastructure)를 연동한 바이오보안 토큰의 이용에 있어서 사용자의 바이오인식 정보를 보호하면서 바이오인식 정보를 이용하여 보안 수준이 높은 사용자 인증이 가능한 기법을 제시한다.

• Nuclear Engineering and Technology
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• 제51권1호
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• pp.214-220
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• 2019

Thermochemical cycles have been predominantly used for energy transformation from heat to stored chemical free energy in the form of hydrogen. The thermochemical cycle based on uranium (UTC), proposed by Oak Ridge National Laboratory, has been considered as a better alternative compared to other thermochemical cycles mainly due to its safety and high efficiency. UTC process includes three steps, in which only the first step is unique. Hydrogen production apparatus with hectogram reactants was designed in this study. The results showed that high yield hydrogen was obtained, which was determined by drainage method. The results also indicated that the chemical conversion rate of hydrogen production was in direct proportion to the mass of $Na_2CO_3$, while the solid product was $Na_2UO_4$, instead of $Na_2U_2O_7$. Nevertheless the thermochemical cycle used for hydrogen generation can be closed, and chemical compounds used in these processes can also be recycled. So the cycle with $Na_2UO_4$ as its first reaction product has an advantage over the proposed UTC process, attributed to the fast reaction rate and high hydrogen yield in the first reaction step.