• Nuclear Engineering and Technology
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• 제46권3호
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• pp.381-386
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• 2014

A highly reliable safety class controller for NPPs (Nuclear Power Plants) is mandatory as even a minor malfunction can lead to disastrous consequences for people, the environment or the facility. In order to enhance the reliability of a safety class digital controller for NPPs, we employed a diversity approach, in which a PLC-type controller and a PLD-type controller are to be operated in parallel. We built and used structured testbenches based on the classes supported by UVM for functional verification of the PLD-type controller designed for NPPs. We incorporated a UVM register model into the testbenches in order to increase the controllability and the observability of the DUT(Device Under Test). With the increased testability, we could easily verify the datapaths between I/O ports and the register sets of the DUT, otherwise we had to perform black box tests for the datapaths, which is very cumbersome and time consuming. We were also able to perform constrained random verification very easily and systematically. From the study, we confirmed the various advantages of using the UVM register model in verification such as scalability, reusability and interoperability, and set some design guidelines for verification of the NPP controllers.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.409-412
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• 2006

In process of reinforced concrete(RC) box structure, the heat of hydration may cause serious thermal cracking problems. In order to eliminate hydration heat of mass concrete, this paper reports results of hydration heat control in mass concrete using the OCHP(Oscillating Capillary tube Heat Pipe). Recently OCHP is drawn special attention from these points of low cost as well as short construction schedule for the manufacturing of heat exchanger, flexibility, simplification and high performance. There were three RC box molds$(1.2{\times}1.2{\times}1.2m)$ which shows a difference as compared with each other. One was not equipped with OCHP. While others were equipped with OCHP and these were cooled with air natural convection and spraying water respectively. The OCHP was composed of copper pipe with 12 turns(O.D : 4mm, I.D : 2.8mm). The working fluid was R-22 and its charging ratio was 30(Vol. %). In order to analyze the distribution of temperature and index figure of thermal crack in sequential placement of mass concrete, we used HYCON of computer program. As a result of the experiment, the peak temperature decreased about $15.6\sim23.4^{\circ}C$ than the general specimen and the probability of thermal crack generated in mass concrete decreased up to 0%.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권5호
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• pp.476-484
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• 2015

Due to the recent advances in non-volatile memory technologies such as PCM, a new memory hierarchy of computer systems is expected to appear. In this paper, we explore the performance of PCM-based swap systems and discuss how this system can be managed efficiently. Specifically, we introduce three management techniques. First, we show that the page fault handling time can be reduced by attaching PCM on DIMM slots, thereby eliminating the software stack overhead of block I/O and the context switch time. Second, we show that it is effective to reduce the page size and turn off the read-ahead option under the PCM swap system where the page fault handling time is sufficiently small. Third, we show that the performance is not degraded even with a small DRAM memory under a PCM swap device; this leads to the reduction of DRAM's energy consumption significantly compared to HDD-based swap systems. We expect that the result of this paper will lead to the transition of the legacy swap system structure of "large memory - slow swap" to a new paradigm of "small memory - fast swap."

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.865-870
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• 2001

For pneumatic system control, we need a data transmission system with high speed and high reliability or information interchange between main computer and solenoid valves and I/O devices. This paper presents a set of design techniques for a data communication system that is mainly used for pneumatic system control. For this purpose, we first designed hardware modules for an interface between central control module and local node that handles the operation of solenoid valves. In addition we developed a communication protocol for construction of RS-485 based multidrop network, and this protocol is basically designed with a kind of polling technique. Finally we evaluated performance of the developed system. The field test results show that, even under high noise environment, the data transmission of 375Kbps rate is possible up to 1,000m without using repeater. In addition, the system developed in this research is proved to be used easily for extension of a communication network because of its module structure.

• Steel and Composite Structures
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• 제33권6호
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• pp.865-875
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• 2019

The current article proposed to develop a geometrical model for the analysis and modelling of the uniaxial functionally graded structure using the higher-order displacement kinematics with and without the presence of porosity including the distribution. Additionally, the formulation is capable of modelling three different kinds of grading patterns i.e., Power-law, sigmoid and exponential distribution of the individual constituents through the thickness direction. Also, the model includes the distribution of porosity (even and uneven kind) through the panel thickness. The structural governing equation of the porous graded structure is obtained (Hamilton's principle) and solved mathematically by means of the isoparametric finite element technique. Initially, the linear frequency parameters are obtained for different geometrical configuration via own computer code. The comparison and the corresponding convergence studies are performed for the unidirectional FG structure for the validation purpose. Finally, the impact of different influencing parameters like aspect ratio (O), thickness ratio (S), curvature ratio (R/h), porosity index (λ), type of porosity (even or uneven), power-law exponent (n), boundary condition on the free vibration characteristics are obtained for the FG panel and discussed in details.

• 설비공학논문집
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• 제6권4호
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• pp.380-387
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• 1994

An experimental study was performed to investigate the characteristics of refrigerant flow rate control and superheat in an evaporator with an electronic expansion valve(EEV). The EEV used in this study was devised using a needle valve coupled with a stepping motor controlled by a personal computer. A Pill control equation was used to control the superheat of the evaporator and to set the superheat to $5^{\circ}C$. In order to determine an optimum running condition for the system, Pill parameters were varied for the wide range of values. The running condition of an air conditioning system with a PI control was reasonably stable compared with that of the Pill control. Experimental results for the PI control using parameter values, $K_p=1.5$, $T_i=400(sec)$ and $T_s=6(sec)$ show that the superheat reached its target value. When external disturbances were introduced to the system, the superheat target value was reached within about 3 minutes. When the EEV was applied to the air conditioning system driven by an inverter, room temperature control was excellent.

• 대한전자공학회논문지
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• 제20권3호
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• pp.61-68
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• 1983

본 논문에서는 데이터 신호의 통계적 다중화에 관한 제문제들이 취급되었다. 먼저 한정된 waiting room을 가진 시스템에서 데이타 신호가 일정한 속도로 출력된다고 가정하고 batch-poisson 분포의 신호가 입력될 때의 queueing model을 검토하였다. 즉. 신호량과 신호의 평균길이를 변수로 하여 buffer의 크기, overflow의 확률 및 buffering으로 야기되는 queueing 지연시간 등을 살펴보았다. 그리고 데이터 신호의 통계적 다중화 시스템에 관한 실제 모델을 제시하여 마이크로프로그래밍을 통한 하드웨어 구현에 기본이 되게 하였다. 제안된 실제 모델은 buffer의 동적제어방식을 응용하여 설계되었으며 효율적인 I/O프로세스가 되도록 마련하였다. 끝으로. 이 시스템 모델의 성능을 알아보기 위하여 여러 조건에서의 컴퓨터 시뮬레이션을 행하였다. 이 연구로 얻어진 제반 결과는 일반적인 buffer설계에 지침이 될 수 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.309-311
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• 1995

Recently, a power supply system of the telecommunication equipments with monitoring function has been widely studied. In the power supply system which is apart from the central station, it is required to check and test the operating states of the system at the central station. In this paper, the power supply system with monitoring function is discussed. In the system, the Full-Bridge converter is designed as a power supply and it has the ratings of DC 280-340V input and DC 48V, 480W output. And the monitoring part of the system is composed of a voltage and current sensing unit A/D converter, I/O card, and a personal computer. The operating states of the system is monitored by checking the voltage and current variation at input and output, and it is represented by graphical modes. By conducting the experiment, it is confirmed that the operating states of the system is well monitored.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2005년도 춘계학술발표대회
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• pp.1667-1670
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• 2005

본 논문에서는 차세대 통신 플랫폼을 위한 PCI Express의 전송계층과 데이터 연결계층의 모든 기능을 지원하는 PCI Express 컨트롤러를 설계하였다. 설계되어진 컨트롤러는 재전송 매커니즘을 효과적으로 지원하기 위해 제안되어진 송신버퍼 구조를 가지고 있다. 이 버퍼 구조는 전송 버퍼와 재전송 버퍼를 한 개의 버퍼로 통합하여 재전송 버퍼의 공간을 유동적으로 할당할 수 있는 방법이다. 또한 설계되어진 컨트롤러의 송신단 전송계층은 제안되어진 버퍼 구조 효과적으로 지원하도록 설계되어 졌다. 설계 되어진 컨트롤러의 각 블록을 효과적으로 관리하기 위해 80C51 마이크로프로세서를 내장하여 PCI Express 프로토콜을 제공하는 프로그램을 코딩하여 포팅하였다. 또한 설계되어진 컨트롤러의 검증을 위해, Host Bridge, 로컬 마스터 디바이스, 로컬 슬레이브 디바이스를 버스 동작 모델로 구성된 테스트 벤치도 제안하였다. 또한 실제 PCI Express 프로토콜 상에서 발생할 수 있는 모든 경우를 발생 하도록 하기 위해, 각 버스 동작 모델을 위한 어셈블러 명령어들을 정의 하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 하계학술대회 논문집
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• pp.433-436
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• 1990

An optimal Stabilization technique for a bilinear in duction model is introduced. This technique includes to o parts; the one is an stabilization control using Lyap unov Function which has the form of a sum of linear and quadratic function of the state variables, and the other is an optimal control using the performance index which depends on the choice of the elements of the Ly apunov matrices concerning both the state variables and the input variables. Therefore, induction motor is drived with the shorter transient time of the state variables and with the smaller overshoot of the ones, simulation results are obtained from a digital computer. Experimental ones are obtained from implementation of the optimizing controller using 8086 microprocessor kits and analog circuits are compared.