• Proceedings of the KIEE Conference
• /
• 2004.11c
• /
• pp.641-643
• /
• 2004

Liquid Zone Control System controls the power of heavy water reactor. Changing the level of each zone compartment regulates one local zone power of 14 zone powers, iud the level is limited less than 90% by the control algorithm to prevent the flood. In recent years, the level and the power was controlled oscillatory in the upper zones. To find out the condition of cycling, the zone control system was modelled with the linear difference equations and identified using parameter estimation. The pole-zero plot showed that the major pole was near the stability boundary, and the system had oscillatory characteristics in nature.

• Proceedings of the Korean Nuclear Society Conference
• /
• 2003.05a
• /
• pp.128.2-128.2
• /
• 2003

• Proceedings of the Korean Nuclear Society Conference
• /
• 2004.05a
• /
• pp.88.2-88.2
• /
• 2004

• Proceedings of the Korean Nuclear Society Conference
• /
• 2003.10a
• /
• pp.225.1-225.1
• /
• 2003

• Proceedings of the Korean Nuclear Society Conference
• /
• 2005.10a
• /
• pp.472-473
• /
• 2005

• Nuclear Engineering and Technology
• /
• v.40 no.7
• /
• pp.561-570
• /
• 2008

When reactivity insertion such as refueling occurs in CANDU reactors, the power and the water levels are tilted in the upper outer zone of the LZCS (Liquid Zone Control System) and fluctuate unstably for a certain period of time (1-5 days). The instability described above is observed in most CANDU reactors in service around the world, but its root cause is unidentified and no solutions to this problem have been established. Therefore, this study attempted to prove experimentally and analytically that the root cause lies in the hold-up of light water on the top of the TSP (Tube Support Plate) due to the mismatch between net volumetric flow rate of light water and helium crossing the narrowed porous TSP installed within the LZCS compartment. Our method was to perform a hydrodynamic simulation of in/outflow of light water and helium. Two solutions for the aforementioned instability of LZCS are suggested. One is to regulate the compartment for both inflowing helium gas and outflowing light water; the other is to enlarge the flow paths of helium and light water within TSP. The former may be applicable to nuclear reactors in service and the latter to those planned for construction.

• Journal of Institute of Convergence Technology
• /
• v.3 no.1
• /
• pp.19-23
• /
• 2013

This study is concerned with air-conditioning system in use of thermoelectric device. It is introduced that the well designed structures for better cooling & heating performance with high efficiency. And also it is performed that the system performance test of four types trial products for the use of hybrid commercial vehicle. System performance is affected by many component parts, especially heat sink design & power control method. It is applied that dual extrusive fin tube with buffer zone for the effective radiating of circulating liquid in tube. And also it is applied that power supply method with constant-current system. It is attained that system cooling capacity is 1.2kW, COP is 0.95.

• Journal of Environmental Policy
• /
• v.2 no.1
• /
• pp.31-49
• /
• 2003

It is difficult to examine the causal relation of pollution damages because the time gap between pollution cause and effect is large and new pollutants are continuously being produced. Their many environmental effects are not promptly studied. As both the study of causal relation about pollution and the pollutant treatment are becoming highly advanced by the development of science and environmental technology, both the economy and balance on environmental regulation may be discussed. It is reasonable to decide environmental policy in consideration of close relation between both the generation and resolution of environmental problems and of technological developments because environmental problems are related to complicated social problems and scientific technologies. First item in policy decision about environmental control and management is preferentially to consider the way of prevention. It is necessary to prevent pollution by regulating the installment of environmental pollution facility into the environmentally sensitive areas, like water supply source and to regulate land utilization as a method to achieve pollution prevention. Second is a consideration of environmental technology development. This is a solution which can accomplish the development of environmental technology and the reinforcement of economic competition. Third is the coexistence of environment and economy. It is necessary to consider economy in connection with environmental problems and environment in economic problem. Then, we can enjoy a healthy life as well as economic affluence. Fourth is the enlargement of environmental management means. Environmental management means must be diversified because environmental cause and effect are varied. For Improving the land use regulation system, it is necessary to consider both land use regulation status and pollutant toxicity with the development of environmental technology. Land use must be approached by classifying land to 3 levels; water source protection zone and water front zone, special zone 1 and 2, rancus and other zones. Land regulation policy to prevent any accident in water source protection zone, waterfront zone, and special zone must be continuously upgraded. However, economical consideration in other zones is required by the development of environmental technology.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.6
• /
• pp.788-794
• /
• 2002

In liquid rocket engine, propellant feed rate is proportional to approximately square root of the pressure difference between injector head and combustion chamber. This ΔP depends on the engine design, but in general on the order of 50psi. However, during ignition period, especially for the pressurized feed system, combustion chamber pressure is almost atmospheric and large ΔP causes over flow of propellants which may lead to catastrophic accident due to hard start. Hard start may be prevented by applying cavitating venturi or/and two step ignition. In cavitating venturi, evaporated propellants near the venturi throat become chocked and flow rate depends on only upstream condition. In two step ignition propellants are supplied to the liquid engine in two different flow rate. First step, to avoid hard start, small amount of propellants are supplied to build up chamber pressure in safe zone, then full propellants to ensure design pressure. In this study, both cavitating venturi and two step ignition method were used for the hot test and hard start problem was completely solved.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.151-157
• /
• 2005

In the chemical, mineral and electronics industries, mechanically stirred tanks are widely used for complex liquid and particle mixing processes. In order to understand the complex phenomena that occur in such tanks, it is necessary to investigate flow field in the vessel. Most difficulty on the numerical analysis of stirred tank flow field focused particularly on free surface analysis. In order to decrease the dead zone and improve the flow efficiency of a system with free surface, this paper presents a new method that overcomes free surface effects by properly combining the benefits of using experiment and 3-D CFD. This method is applied to study the mixing flow in an agitated tank. From the results of experimental studies using the PIV (particle image velocimetry) system, the distribution of mixing flow including free surface are obtained. And these values that are expressed as a velocity vector field have been patched for simulating the free surface. The results of velocity distribution obtained by 3-D CFD are compared with those of experimental results. The experimental data and the simulation results are in good agreement.