• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.4
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• pp.253-262
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• 1992

A numerical procedure is introduced to calculate local ventilation effectiveness using the definitions of local decay rate and local mean age. A low Reynolds number $k-{\varepsilon}$ model is implemented to calculate steady state turbulent velocity distributions, and a step-down method is used to calculate transient concentration distributions. Simulations are carried out for several different values of air change rates and several different diffuser angles in a two-dimensional model of a half scale office room. The results show that the local ventilation effectiveness within a room could vary significantly from one location to another. The nominal air change rate based on the assumption of complete mixing of room air does not provide the local ventilation effectiveness information. It is numerically proved that the local mean age distribution obtained from the transient calculation is equivalent to the steady state concentration distribution with homogeneously distributed contaminant sources.

• Steel and Composite Structures
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• v.6 no.6
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• pp.479-491
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• 2006

Structures in seismic regions are designed to dissipate seismic energy input through inelastic deformations. Structural or component failure occurs when the hysteretic energy demand for a structure or component subject to an earthquake ground motion (EQGM) exceeds its hysteretic energy dissipation capacity. This paper presents a study on identifying the hysteretic energy demand and distribution throughout the height of regular steel moment resisting frames (SMRFs) subject to severe EQGMs. For this purpose, non-linear dynamic time history (NDTH) analyses were carried out on regular low-, medium-, and high-rise steel SMRFs. An ensemble of ninety EQGMs recorded on different soil types was used in the study. The results show that the hysteretic energy demand decreases from the bottom stories to the upper stories and for high-rise structures, most of the hysteretic energy is dissipated by the bottom stories. The decrease is quite significant, especially, for medium- and high-rise structures.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.505-510
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• 2008

FBG Sensor, which is smaller than strain gauge and has better durability and does not have a noise from electromagnetic waves, was adapted to develope a smart anchor. A series of pullout tests were performed to verify the feasibility of smart anchor and find out the load transfer mechanism around the steel wire fixed to rock with grout. Distribution of shear stresses at steel wire-grout interface is assessed from the measured strain distribution by the optical fiber sensors and compared with stress distributions predicted by Farmer's and Aydan's formulas. It was found that present theoretical formulas may underestimate the failure depth and magnitude of shear stresses when the pullout loads increase.

• International Journal of Safety
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• v.9 no.1
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• pp.12-20
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• 2010

In this study, a series of random field test and dynamic analysis in the time domain were carried out in order to find in the reason of fatigue damage of the main and the secondary members in the 3-span continuous steel plate girder railway bridge being under in service over 60 years. From the measured and the analyzed results, the stress distribution patterns were investigated for the members with fatigue damage. In addition, global and local numerical stress analysis was performed for the members damaged severely by corrosion, to estimate variation of the distribution by corrosion. Finally, a reasonable cut-off ratio in the steel plate railway bridge will be proposed by analyzing the equivalent stress ranges according the ratio.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.3
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• pp.338-345
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• 1999

The objective of this study is to developed the refrigeration vehicle system installed eutectic olu-tion plates which consists of copper tubes carrying the refrigerant between two aluminum plates and the space between the plates filled with eutectic solution. The numerical analysis for the loca-tion of plates to get the uniform low temperature distribution in storage space was carried out and the result showed that the top left-side and right-side walls were the proper places to install plates. For three different concentrations of ethylene glycol solution the temperature distribution of inside space were measured during the day time of summer and the 21% solution was found to be properto sustain the temperature of $5-10^{\circ}C$ for milk transportation. The result showed that the refrigeration truck installed eutectic plates was very efficient to keep the milk fresh during vehicle transportation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.8
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• pp.1069-1076
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• 2000

As the environmental problems grow, the regulation of the pollutants emitted from power plants increases. Most of the pollutants in particle phase are removed by particle removal facilities, but fine particles between 0.1 micron and I micron in diameter have a low removal efficiency compared to particles in other size ranges. Therefore the present concern has concentrated on the removal of those fine particles. The purpose of this study is to grow fine particles by condensation to the range larger than I micron. Theoretically the general dynamic equation is solved with an assumption that the particle size follows a log-normal distribution to calculate the temporal behavior of the size distribution. Experiments have been carried out to compare the results with the theoretical predictions. Particles grown by condensation are sampled by impactors and observed with SEM photographs.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.2
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• pp.221-227
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• 2009

The study of the solidification process of welded metal is carried out using the finite element method, which is the basic study for optimal design. In the analysis of temperature, the welded zone is cooled as the result of heat conduction to the base metal and heat transfer to the circumference. In the early phase of the temperature in base metal zone is little changed. But after the rise in temperature the whole area is cooled gradually and uniformly with the lapse of 10 seconds, and a temperature change is hardly occurred in the radial direction but in the axial direction.

• Proceedings of the Korean DIstribution Association Conference
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• 2000.10a
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• pp.187-205
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• 2000

6 Sigma movement is the quality innovation activity which Motorola, a nineteen eighties' top-ranking American company of electronics and communication, has started to survive the Japanese companies' frightening gami-gaze. In early days, it's just applicated for reducing customers' complain by eliminations inferior goods centering round producing activity and filling up the competitive market's demand for price and delivery deadline. Nowaday, 6 Sigma application has created a boom extending to a company's most activity fields without any exact scrutiny of 6 Sigma. Although 6 Sigma movement starts from the question of what customers want not by cutting off the inferiority rate but by cutting out causes of producing inferior goods, the service industry has a special character that makes it difficult to compute the level of Sigma. Thus this research examines suitability for introduction of 6 Sigma to the Service Industry.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.686-691
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• 2000

Animation technique from the PIV database is particularly emphasized to give macroscopic and Quantitative description of complex flow fields. As an example, an experimental study was carried out investigate the fundamental (low characteristics of the freezer with the domestic refrigerator. Optimized cross correlation identification to obtain velocity vectors is implemented by direct calculation of correlation coefficients. Image intensifier CCD camera to cope with illumination problem is arranged for the accurate PIV measurement of large flow field. As a results, continuous pictures of the spatial distribution of the instantaneous and time-mean velocity distribution are displayed in real-time sense.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.2
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• pp.103-110
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• 2003

With significant development of power electronics technology, the proliferation of nonlinear loads such as static power converters has deteriorated power quality in power transmission and distribution systems. Notably, voltage harmonics resulting from current harmonics produced by the nonlinear loads have become a serious problem in many countries. Many photovoltaic power generation systems installed in building systems have harmonics that are the worst object for distribution systems as a utility interactive system, and it tends to spread out continuously. Proposed and implemented in this paper is a multi-function inverter control strategy that allows a shunt active filter function to the power inverter of the photovoltaic power generation system established on a building system. The effectiveness of the proposed system is demonstrated through the simulation of a hypothetical power system using PSCAD/EMTDC.