• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.17 no.5
• /
• pp.583-589
• /
• 1988

Condensation of water vapor into an absorbent liquid of LiBr-water solution falling over a bank of water cooled horizontal tubes was investigated theoretically. The governing conservation equation for a re-defined physical transport phenomena were solved numerically using a finite difference method. Raw parameters were used in this study, since reliable experimental data is required prior to a dimensionless parametric study. The average values of wall heat transfer coefficient and interfacial absorption rate were defined to see the system performance. Other parameters include tube diameter, streamwise coordinate (and number of tubes in row), mass flow rate, and the wall temperature. The effects of these quantities on the absorption processes and suggestions for a rational system design have been presented.

• Proceedings of the SAREK Conference
• /
• 2007.11a
• /
• pp.167-175
• /
• 2007

A predictive pulse control strategy as a means of improving the energy efficiency of radiant floor heating systems is explored. Experiments at the apartment with floor heating system are conducted to assess and compare the energy performance of the predictive pulse control strategy with an existing conventional control strategy. The Results showed that new suggested PPCM( Predictive Pulse Control Method) was available to decrease the gap of $1{\sim}1.5^{\circ}C$ between maximum and minimum indoor temperature of each rooms. Therefore PPCM method was favor to radiant floor heating system which have a delay time of 10-20 minutes for heat transfer by floor layers.

• Proceedings of the SAREK Conference
• /
• 2007.11a
• /
• pp.52-57
• /
• 2007

The control characteristics for radiant panel heating system with automatic thermostatic valves were researched by computer simulation and experiment. The unsteady energy analysis using equivalent R-C circuit method and radiation heat transfer analysis of enclosure analysis method with simple structured rooms was performed. The results of flow rate changes of the simulation study are good fit with the ones of experimental one.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.51 no.6
• /
• pp.271-277
• /
• 2002

In this paper, a MEMS silicon package is newly designed, fabricated for HMIC, and characterized for microwave and millimeter-wave device applications. The proposed package is fabricated by using two high resistivity silicon substrates and surface/bulk micromachining technology. It has a good performance characteristic such as -20㏈ of $S_11$/ and -0.3㏈ of $S_21$ up to 20㎓, which is useful in microwave region. It has also better heat transfer characteristics than the commonly used ceramic package. Since the proposed silicon MEMS package is easy to fabricate and wafer level chip scale packaging is also possible, the production cost can be much lower than the ceramic package. Since it will be a promising low-cost package for mobile/wireless applications.

• Journal of the korean Society of Automotive Engineers
• /
• v.9 no.3
• /
• pp.85-93
• /
• 1987

The intake system of 4-cycle, 4-cylinder reciprocating engine is investigated the simple model composed of vessel, duct and throttling part. The numerical calculation based on the simulation is performed for the flow phenomena including heat transfer, friction and bend of duct at each part. In the multi-cylinder engine, the volumetric efficiency is increased a little as the junction location is closed to cylinder at the engine speed having maximum volumetric efficiency. The configuration and dimension of intake system have an influence on the inertia effect by resistance and pressure variation, and the magnitude of that is varied by the engine speed. Thus the volumetric efficiency is correlative to them. The volumetric efficiency is high as the intake valve close is advanced at the low engine speed, and is delayed at high speed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.05a
• /
• pp.385-388
• /
• 2005

The use of magnesium alloys meets the need of reducing weight of componests(especially in automotive and aerospace industry) keeping unmodified their mechanical properties. The adoption of magnesium alloys in sheet forming processes is still limited, due to their low formability at room temperature caused by the hexagonal crystal structure. In this study, the authors aim to understand the process condition which can lead to a successful improvement in the formability of a magnesium alloy(AZ31). Experiment and simulations of deep drawing were doned at various warm temperature for the blank and tool(holde and die)while the punch was kept at room temperature by cooling wale. in order to confirm that the deep drawing performance of magnesium alloy can be considerably enhanced with using the local heating and cooling technique.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.427-431
• /
• 2005

In this study, 6' GaAs wafer bonding system is designed and optimized to bond 6 inches device wafer and material wafer. Bonding process is performed in vacuum environment and resin is used to bond two wafers. Vacuum module and double heating mechanisms are adopted to minimize wafer warpage and void. Structure and heat transfer analysis, et al of the core modules review the designed mechanisms are very effective in performance improvement. As a result, high productivity (tack time cut-down) and stabilized process can be obtained by reducing breakage failure of wafer.

• Nuclear Engineering and Technology
• /
• v.35 no.2
• /
• pp.121-132
• /
• 2003

To reduce the construction cost and enhance the safety of sodium cooled liquid metal reactors, various kinds of new design concepts were evaluated using the KALIMER operation condition. The required equipment sizes were set for plant electricity output to be similar to that of KALIMER. The evaluations were made focusing on the plant performance and implementation practicality. Each design concept was evaluated for the concept itself and design impacts to interfacing systems. Through the evaluation of the concepts, it was found that the most favorable design concept is the integrated steam generator with forced convection using lead bismuth as the intermediate heat transfer fluid between the primary sodium tube and feed water/steam tube in the steam generator.

• Journal of Korean Association for Spatial Structures
• /
• v.19 no.3
• /
• pp.77-83
• /
• 2019

AU(A plus U-shaped) composite beam was developed for reducing the story height in the residential buildings, and saving the cosrtuction cost of floor structures. Structural performance and economic feasibility of the composite beam have been sufficiently approved through the structural experiments and the analytical studies. Fire safety for the practical application of the composite beam has also been verified through the fire resistance tests and the heat transfer analyses. In this study 2-points bending tests were performed on the four specimens already tested for fire resistance to evaluate the residual bending strength of AU composite beam after fire accident. The same bending test was performed on the one fresh specimen having the same section and span of the specimens for practically comparative study.

• Journal of ILASS-Korea
• /
• v.28 no.1
• /
• pp.10-15
• /
• 2023

Recently, various types of towels and dishcloth dryer products are being widely distributed in Korea. Evaluation methods for water absorption properties of various fabrics have been developed, and there are many studies using them. This study newly intended that whether it is possible to obtain data that can quantitatively analyze the water absorption characteristics of various fabrics, to show the correlation between the water absorption height and the amount of water (water holdup) absorbed, and to experimentally suggest the applicability to evaluate the drying capacity of towel dryer using IR camera. Through these experiments, it was confirmed that quantitative data on the water absorption height of various fabrics can be measured using an IR camera and can be clearly applied to the performance evaluation of actual products.