• Proceedings of the SAREK Conference
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.789-794
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• 2006

The potential impacts of climate change on heating and cooling energy demand were investigated by means of transient building energy simulations and hourly weather data scenarios for Inchon. Future trends for the 21 st century was assessed based oil climate change scenarios with 7 global climate models(GCMs), We constructed hourly weather data from monthly temperatures and total incident solar radiation ($W/m^2$) and then simulated heating and cooling load by Trnsys 16 for Inchon. For 2004-2080, the selected scenarios made by IPCC foresaw a $3.7-5.8^{\circ}C$rise in mean annual air temperature. In 2004-2080, the annual cooling load for a apartment with internal heat gains increased by 75-165% while the heating load fell by 52-71%. Our analysis showed widely varying shifts in future energy demand depending on the season. Heating costs will significantly decrease whereas more expensive electrical energy will be needed of air conditioning during the summer.

• The Transactions of the Korean Institute of Electrical Engineers A
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• 제52권6호
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• pp.301-306
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• 2003

When a bulk power system experiences a serious disturbance or heavy load trip, the system frequency may drop and even collapse if the total generating power does not supply the system demand sufficiently. Since an isolated power system possesses a lower inertia and comes with limited reserves, the load shedding by under frequency relay becomes an important strategy to keep system natural frequency. This paper presents a scheme to determine the load shedding criteria by using the rate of change of frequency when the large disturbance happens.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.125-130
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• 1999

In order to reduce the forming load of backward extrusion to a feasible level a new backward extrusion processes are proposed. In these process the shape of punch and die for conventional backward extrusion are change to open backward extrusion. To analyse the process numerical simulations by the finite element method has been performed, This simulation gave good results concerning the prediction of the forming load material flow and the corresponding shape of forged products, . These predictions set the limits of the preform shape and forming load depending on the punch and die geometry. The results show that the forming load is reduced significantly when the conventional backward extrusion change to open backward extrusion.

• Proceeding of KASS Symposium
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• 한국공간구조학회 2006년도 춘계 학술발표회 논문집 제3권1호(통권3호)
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• pp.170-174
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• 2006

This paper presents a new nonlinear analysis algorithm which uses the equivalent nodal load for the element stiffness. The equivalent nodal load represents the influence of the stiffness change such as the addition of elements, the deletion of elements, and/or the partial change of element stiffness. The nonlinear analysis of structures using the equivalent load improves the efficiency very much because the inverse of the structural stiffness matrix, which needs a large amount of computation to calculate, is reused in each loading step. In this paper, the concept of nonlinear analysis using the equivalent load for the element stiffness is described and some numerical examples are provided to verify it.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.376-380
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• 2009

Surface acoustic wave (SAW) device is widely used as a bandpass filter, a chemical or physical sensor, and an actuator. In this paper, we propose the capacitive gap measurement system with high precision through the signal processing using SAW device. The research process is mainly composed of theoretical part and experimental part. In theoretical part, equivalent circuit model was used to simulate the SAW response by the change of capacitance. In experimental part, commercialized capacitor was used to see the SAW response by the change of load capacitance. After that, gap adjustment system was made physically and the SAW response by the change of gap which caused the capacitance change was measured. And resolution and stroke was decided comparing the signal change and basic measurement noise level.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제20권5호
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• pp.437-443
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• 2010

SAW device is widely used as band pass filters, chemical or physical sensors, and actuators. In this paper, we propose the capacitive gap measurement system with high precision using SAW device. The research process is mainly composed of theoretical and experimental part. In the theoretical part, equivalent circuit model was used to predict the SAW response by the change of load impedance. In the experimental part, commercialized capacitor was used to see the SAW response by the change of load capacitance to check the feasibility as a sensor unit. After that, experimental setup to measure and adjust the gap was made and the SAW response by the change of gap which caused the capacitance change was measured. Finally, resolution and stroke was decided compared with the signal change and basic measurement noise level.

• Tribology and Lubricants
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• 제11권2호
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• pp.44-55
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• 1995

Frictional characteristics with the change of dynamic parameters, such as stiffness, inertia and damping, in the friction measurement at dry sliding surfaces were experimentally and theoretically investigated throughout the study. Dynamic frictional force and the variation in the normal load were mainly measured at the various conditions of system dynamic parameters with which stiffness in the normal direction, loading mechanisms and test materials were varied. For the normal load, mechanisms using both a dead weight and a pneumatic cylinder were applied, which resulted in change of the inertia and damping of the test rig. Test materials were steel, rosin and PTFE, which have different types of intrinsic frictional characteristics. Test results showed that frictional characteristics under different dynamic parameters could be different even though the operating variables were the same and also they could result in the variation in the normal load, which could consequently affect the wear mechanism.

• Transactions of Materials Processing
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• 제22권2호
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• pp.67-73
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• 2013

The deformation characteristics and microstructure changes in a round copper pipe under biaxial compression was studied using a horizontal compression die. The change of material properties, punch load and deformation behavior were monitored using various compressive deformation rates in the range of 0.5mm/min.~450mm/min. The strains, either tensile or compressive, were estimated from Vickers microhardness test results. The punch load and deformation characteristics of the round copper pipes were found to change greatly at a deformation rate of about 200mm/min. The punch load decreased with increasing compressive deformation rate. The results of numerical simulations agreed well with what was expected from the final microstructure and the hardness profile estimated from the final deformation strains.

• Transactions of the Korean Society of Mechanical Engineers
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• 제8권2호
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• pp.178-183
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• 1984

The stresses in lubricants by external force lead to rise in temperature and drop in viscosty, and the performance of lubricants decrease by this phenomena. The processes of shear stress generation and relaxation are linear under light load condition but those are changed into nonlinearly over a certain limit of load and speed, and this phenomena influences to viscosty change. This study investigates dense fluid which carries property change for high shear rate by using molecular dynamics, and that result can be related to research a behavior of property change of lubricants under high speed and heavy load.

• Korean Journal of Agricultural and Forest Meteorology
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• 제1권1호
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• pp.36-40
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• 1999

A new method was developed to measure underground water level with high reliability. The principle of new method was to detect a change of a buoyant force according to change in water level of underground water measured by the use of a straingage load cell. Field test of the instrument was carried out in Cheju Island. The results were as follows; 1) The present study provided a possibility to develop a new underground water level meter. 2) This new instrument accomplished high reliability at field test in Cheju Island. 3) There is possibility of development of water level meter which measure various range of water level to detect a weight change of a buoyant forcd.