• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.1
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• pp.10-16
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• 2013

This study performed a subjective evaluation of the Semantic Differential (SD) method for living room activities to evaluate the living room lighting environment and investigated the relationship between these through luminance distribution in the space. As a result, three factors-"lightness", "emotion" and "calmness"-have been grouped together. According to the analysis of experimental variables, difference has been observed depending on color temperature, the dimming of the ceiling & cove lights and the use of down lights and a bracket. 'Conversation with Family', 'Having Fun with Family', 'Entertaining Guests' and 'Reading a Book or Newspaper' requires "lightness". In terms of "emotion"-centered activities, 'Watching TV' is the highest, but all three factors are related. In terms of "calmness"-centered activities, 'Relaxing' is the highest.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.4
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• pp.276-289
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• 1989

The airflow characteristics in both the upper plenum and the clean space of clean room are investigated by measuring the pressure distribution of the upper plenum and the velocity profile in the clean space, at the various conditions of the supplied airflow rate, the volume of upper plenum and the air supply type. The performance of vertical air supply type and horizontal air supply type is analyzed in terms of the airflow uniformity which is frequently used in indicating the clean room performance, and the relations among the volume of upper plenum, the supplied airflow rate and the airflow uniformity are confirmed. The results of this experimental study can be applied to the designing of the upper plenum of clean room.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.10
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• pp.908-916
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• 2000

In this paper, the characteristics of moisture ventilation in the lithium ion battery manufacturing dry room are studied numerically using standard $k-\varepsilon$ turbulence model. Both the steady-state and the unsteady behaviors of moisture ventilation are analyzed by considering local and uniform moisture generation. In order to evaluate the characteristics of moisture ventilation, three scales of ventilation efficiency and characteristic ventilation time are presented from the numerical results. It was shown that moisture distribution was dependent strongly on the flow field. The characteristics of moisture ventilation were improved by 20% and 40% in terms of the 1st scale of ventilation efficiency (SVE1) and the 2nd scale of ventilation efficiency (SVE2), respectively, through the modifications of design variables such as the addition of inlets, outlets and partition. A significant improvement in the characteristic ventilation time and the moisture exhaust efficiency was also made by these modifications.

• Journal of computational fluids engineering
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• v.14 no.2
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• pp.39-45
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• 2009

In engine room, proper enclosure system is preferable for reducing noise level but the enclosure system in the engine room causes bad influence on cooling performance due to poor ventilation. Cooling efficiency of the enclosure system can be improved by varying fan speed and proper flow path for ventilation. In this study, numerical analysis is performed to assess cooling effect of the enclosure system using finite volume method. The RNG k-$\varepsilon$ model is adopted for turbulence model along with heat exchanger model and porous media model for heat exchanger analysis, and moving reference frame model for rotational fan. Verification result shows reasonable agreement with experimental data. Analysis results show direct effect of velocity and temperature distribution on cooling ability in the enclosure system. Enclosure system of case B shows high heat transfer coefficient and has the smallest area ratio of opened flow passages which is good for noise level reduction.

• Structural Engineering and Mechanics
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• v.38 no.5
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• pp.633-649
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• 2011

The paper presents a study aimed at understanding some characteristics of an interior explosion within a room with limited or no venting. The explosion may occur in ammunition storage or result from a terrorist action or from a warhead that had penetrated into this room. The study includes numerical simulations of the problem and analytical derivations. Different types of analysis (1-D, 2-D and 3-D analysis) were performed for a room with rigid walls and the results were analyzed. For the 3D problem the effect of the charge size and its location within the room was investigated and a new insight regarding the pressure distribution on the interior wall as function of these parameters has been gained. The numerical analyses were carried out using the Eulerian multi-material approach. Further, an approximate analytical formula to predict the residual internal pressure was developed. The formula is based on the conservation law of total energy and its implementation yields very good agreement with the results obtained numerically using the complete statement of the problem for a wide range of explosive weights and room sizes that is expressed through a non-dimensional parameter. This new formula is superior to existing literature recommendations and compares considerably better with the above numerical results.

• Journal of Drive and Control
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• v.19 no.1
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• pp.62-68
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• 2022

Considering the characteristics of industrial machines that lack vehicle-induced wind, forced convection by a cooling fan is mostly required. Therefore, numerical analysis of an engine room is usually performed to examine the cooling performance in the room. However, most engine rooms consist of a number of parts and components at specific positions, leading to high costs for numerical modeling and simulation. In this paper, a new methodology for three-dimensional computer-assisted design simplification was proposed, especially for the pile of components and parts at the engine room outlet. A porous media model and regression analysis were used to derive a meta-model for imitating the flow rate reduction at the outlet by the pile. The results showed that the fitted model was reasonable considering the coefficient of determination. The final numerical model of the engine room was then used to simulate the velocity distribution by changing the mass flow rate at the outlet. The results showed that both velocity distributions were significantly changed in each case and the meta-model was valid in imitating the flow rate reduction by some piles of components and parts.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.E
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• pp.1-7
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• 1998

This paper presents an experimental study for understanding the indoor air quality in a room. A model room, which had a ceiling-mounted supply and a sidewall-mounted exhaust, was used to examine the effect of air exchange rate (AER) and contaminant source location (CSL) as a function of the elapsed time. A tracer gas method, using carbon monoxide tracer, gas analyzers, and a data acquisition system, was applied to study the ventilation air distribution and the tracer removal efficiency, so-called pollutant removal efficiency, in the model room. The experiment was composed of two parts; firstly the AER was varied to examine its effect on the ventilation air distribution and the ventilation effectiveness and secondly both AER and CSL were considered to determine their effect on the pollutant removal efficiency. It was found that the ventilation effectiveness in the model was proportional to AER but not linearly. It was also found that changing the CSL can improve the pollutant removal efficiency. In some cases, the efficiency improvement by increasing AER was achieved by simply changing CSL.

• Nuclear Engineering and Technology
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• v.38 no.5
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• pp.449-454
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• 2006

Neutron imaging technique was used to investigate the water distribution and movement in Polymer Electrolyte Membrane Fuel Cell (PEMFC) at HANARO, KAERI. The Feasibility tests were performed in the first and second exposure rooms at the neutron radiography facility (NRF) at HANARO in order to check the ability of each exposure room, respectively. The feasibility test apparatus was composed of water and pressurized air before making up the actual test apparatus. Due to the low neutron intensity in the second exposure room, the exposure time was too long to investigate the transient phenomena of PEMFC. Although the exposure time was improved to 0.1 sec in the first exposure room, it was difficult to discriminate detail water movement at the channel due to the high noise level. Therefore, the experimental setup must be optimized according to the test conditions. Water discharge characteristics were investigated under different flow field geometries by using feasibility test apparatus and the neutron imaging technique. The water discharge characteristics of a 3-parallel serpentine are superior to those of a 1-parallel serpentine, but water at Membrane Electrode Assembly (MEA) was not removed, regardless of the flow field type.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.853-856
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• 2009

Test models which have geometrical similarities with a real room air conditioner (RAC) have been manufactured including visualization windows so that a laser beam can pass through a cross flow fan. Then, flow distributions of the RAC have been investigated using a visualization technique such as a Particle Image Velocimetry (PIV) to analyze an efficiency and noise of the RAC. Pitot tubes have also been used to measure the flow velocity inside the RAC with various positions to confirm the measurement accuracy of the PIV technique. The measured flow velocities have been analyzed and new designs of the RAC have been proposed to improve the efficiency and to reduce the noise for the RAC in this study.

• Journal of Korea Foundry Society
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• v.4 no.1
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• pp.5-11
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• 1984

Green compressive strength, permeability, deformation, flowability, compactability and green hardness values at room temperature are dependable on the grain distribution and grain shape. The results obtained under constant moisture (4% for sand) and bentonite (8% for sand) were as follows; 1. With decreasing grain size, surface area of sand grain was increased. 2. With decreasing grain size, coefficient of angularity was increased. 3. As surface area increased from $8926.43cm^2$ to $21211.16cm^2$ , green compressive strength was increased from $210.93\;g/cm^2$ to $449.98\;g/cm^2$, hardness was increased from 76.7 to 82.3, but permeability was decreased from $411.7\;{\frac{\;cc\;{\cdot}\;cm\;}{atm\;{\cdot}\;cm^2\;{\cdot}\;min.}}$ to $113.7\;{\frac{\;cc\;{\cdot}\;mm\;}{atm\;{\cdot}\;cm^2\;{\cdot}\;min.}}$ 4. As surface area increased from $8926.43\;cm^2$ to $21211.16\;cm^2$, flowability was decreased from 82.3% to 80.8%, deformation was decreased from $67.1\;cm\;{\times}\;10^{-3}$ to $54.6\;cm\;{\times}\;10^{-3}$, but compactability was increased from 44.8% to 54.3%. 5. Room temperature properties of molding sand were affected by variation of surface area.