• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.815-820
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• 1993

Robotic technology has been grown up conspicuously by its versatility. KAERI has been involved in one of facets of robot industry to keep abreast of rapid evolving technologies In robotic field and has launched long-term R&D plan to assure the stable nuclear energy. In this paper, the latest development status of teleoperated robot system has been presented with emphasis the configuration of overall control system with 3 dimensional graphic system that provides operators with tele-presence situation. This robot system under development, composed of master-slave arm with controller and graphic simulator, is operated by a master manipulator to enable an installation and removal operation of nozzle dam system for steam generator. Evaluation and analysis has been carried out to get optimal parameters of robot system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1519-1522
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• 1996

In this paper, we have developed a tele-robotic system for nozzle dam installation/removal works and tube relating maintenance works inside unclear power plant steam generator. Developed tele-robotic system consists of many hardwares including robot and a control system. Based on the 3 dimensional graphic simulation, a 6 D.O.F. hydraulic actuated robot and a 2 D.O.F. robot install/removal device have been developed. And also we deviced special tools for nozzle dam carry and bolting. For the tele-robot and other devices to be controlled at the nonradioactive area outside reactor containment building, we developed a tele-robot control system consisting of supervisory controller and remote controller.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1527-1530
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• 1996

Telerobot system is being developed for the application to nuclear power plants by Korea Atomic Energy Research Institute. Human-machine interaction and interface are very important elements of telerobotic systems. The main purpose of this study is developing a control system based on 3-D graphic techniques for the easy user interface and realistic visual I information supply. This system possesses the abilities for (1) virtual work, environment modelling and simulation, (2) kinematic animation include redundant behavior (3) interfacing with a real robot system, (4) transformation between real and virtual mode within the same graphics system. This system is especially focused on enhancing the overall efficiency and reliably of nozzle dam installation task inside water chamber of steam generator in nuclear power plant.

• 소성∙가공
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• 제3권1호
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• pp.63-83
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• 1994

In this paper, the slab method have been applied to investigate the strip casting process in which hot coil is produced from molten steel directly. In the twin roll strip casting process, molten steel supplied by the nozzle cools and solidifies due to the heat extraction effect of the rolls and hot rolling of the solidified shell takes place simultaneously. The analysis of hot rolling has been carried out by using the existing results of solidification analysis for the twin roll strip casting process. The current slab method provides basic design data such as roll separation force, rolling torque, rolling power as well as end dam separation force which are required to design strip caster. The effect of friction on the basic process parameters are investigated also. It is shown that the use of appropriate friction coefficient is important and that the characteristics of hot rolling in the twin-roll strip casting process is quite different from the conventional hot rolling processes.

• Journal of Radiation Protection and Research
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• 제18권1호
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• pp.71-82
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• 1993

원자력 발전소 작업과의 피폭량은 발전소의 안전 운영에 관한 척도일 뿐 아니라, 일반 대중이 원자력 발전의 안전을 평가하는 기본 요소이다. 또한, 최근 ICRP 60에 의한 개인 피폭선량 한도의 하향조정 권고는 지속적인 피폭저감에의 노력을 요구하고 있다. 본 논문에서는 작업자의 피폭저감에 관한 대안선정시 사용할 수 있는 최적화 기법을 제시하고 실제로 원전 운영자예 의해 제안된 대안들을 검토하는데 이 기법을 적용하여 보았다. 분석과정에서 기본분석이외에 가변 경제변수를 고려한 민감도 분석을 통해 계산 결과의 불확실성을 보완하였다. 분석결과를 살펴보면, 먼저 비용-이득 분석에서는 '증기 발생기 Nozzle Dam 및 Torquing Machine'이 총 이득면에서 가장 우수한 것으로 평가되었고, 다속성 효용 분석의 경우 'Co-No Seal 조임장치'가 가장 높은 효용을 가진 것으로 나타나 약간의 차이를 보이고 있다. 따라서, 최적화 기법의 적용시에는 두 가지이상의 정량적 기법을 보완적으로 사용하고, 정성적 인자도 충분히 고려하는 것이 필요하다.

• 대한기계학회논문집A
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• 제20권6호
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• pp.1762-1772
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• 1996

The main objective of this study is to develop a gripper mechanixm that can be employed for assembly and removal tasks of a nozzle-dam of steam genetator in the process of the nuclear reactor maintenances. Brief description of the open-close thpe gripper mechanism, its position analysis, and its kinematic analysis are given. The optimal design of the gripper mechanism with and without slipping on its two gipping surfaces is considered. As an optimal design index, the ratio of the actuator force of prismatic cylinder to gripping load is proposed. Then, based on this index the oiptimal design is carried out to identify values of optimal design parameters for the gripper dechanism.

• Journal of Mechanical Science and Technology
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• 제14권4호
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• pp.456-465
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• 2000

An experiment was conducted to investigate the aerodynamic losses of high pressure steam turbine nozzle (526A) subjected to a large range of incident angles ($-34^{\circ}\;to\;26^{\circ}$) and exit Mach numbers (0.6 and 1.15). Measurements included downstream Pitot probe traverses, upstream total pressure, and end wall static pressures. Flow visualization techniques such as shadowgraph and color oil flow visualization were performed to complement the measured data. When the exit Mach number for nozzles increased from 0.9 to 1.1 the total pressure loss coefficient increased by a factor of 7 as compared to the total pressure losses measured at subsonic conditions ($M_2<0.9$). For the range of incidence tested, the effect of flow incidence on the total pressure losses is less pronounced. Based on the shadowgraphs taken during the experiment, it' s believed that the large increase in losses at transonic conditions is due to strong shock/ boundary layer interaction that may lead to flow separation on the blade suction surface.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.525-530
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• 1995

The main objective of this study is to develop a gripper mechanism that can be employed for assembly and removal tasks of a nozzle-dam of steam gererator which is one of the nuclear reactor maintenance process. Brief description of the open-close type gripper mechanism, its postion analysis, and its kinematic amalysis are given. The optimal design of the gripper mechanism with slipping on its two gripping surfaces is considered. As an optimaldesign index, the ratio of the actuator force of prismatic cylinder to gripping load is proposed. Then, based on this index the optimal design synthesis is careied out to identify values of optimal design parameters for the gripper mechanism.

• Nuclear Engineering and Technology
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• 제56권5호
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• pp.1874-1879
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• 2024

Owing to strict radiation safety management in Korean nuclear power plants (NPPs), most radiation workers receive very low radiation doses, even lower than the annual dose limit for the general public. However, the occupational dose distribution indicates that some Korean NPP workers receive a relatively higher dose than the average dose. This inequity in radiation exposure could be reduced by providing customized radiation protection measures, such as dose constraints, to workers receiving relatively higher doses. In this study, dose normalization was performed to identify the highest radiation exposure work in Korean pressurized water reactors (PWRs). The results show that most of the occupational exposure in Korean PWRs occurs during the planned maintenance period. Finally, the three highest radiation exposure tasks in Korean PWRs were identified: nozzle dam installation and removal, eddy current testing, and man-way opening and closing.

• 방사선산업학회지
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• 제18권1호
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• pp.23-33
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• 2024

This study was conducted to analyze the characteristics of three high-exposure tasks performed by radiation workers in Korean pressurized water reactors (PWRs) and to identify factors that reduce their exposure during work. Three high-exposure tasks were selected based on a previous study. In this previous study, nozzle dam installation and removal, eddy current testing, and manway opening and closing were determined as high-exposure tasks through normalization (radiation dose per unit time). Based on the analysis of the characteristics of the high-exposure tasks in this study, the high-exposure tasks were steam generator-related tasks performed inside and outside the water chamber. This study analyzed the reduction factors for high-exposure tasks and suggested improvements in terms of time, distance, and shielding. The use of the characteristics of high-exposure tasks and their dose reduction factors enables Korean PWRs to optimize radiation protection for workers who receive relatively high doses.