• Journal of the Korean Wood Science and Technology
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• v.24 no.1
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• pp.95-99
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• 1996

The bending and compression strength properties of two types Rhus verniciflua specimens, which made of no heat-treated wood and heat-treated wood for urushiol extraction, were measured. The heat-treated specimens were finger-jointed with either resorcinol-phenol or polyurethane resin adhesives, and the vertical type bending strength property was also measured in these specimens. The results obtained are as follows ; 1. The correlation coefficient between the compression strength and specific gravity in the specimens of no heat-treated and heat-treated wood was high. However there was no difference in compression strength property as affected by heat treatment. 2 The correlation coefficient between the bending strength and specific gravity in the specimens of no heat-treated and heat-treated wood was also high. However, there was no difference in bending strength property as affected by heat treatment. 3 The bending test showed high correlation between modulus of elasticity and modulus of rupture for the specimens made of no heat-treated and heat-treated wood. However, there was no difference in bending strength property between the specimens made of heat-treated and no heat-treated wood. 4. The efficiencies of bending strength test on the finger-jointed specimens of heat-treated wood with resorcinol-phenol and polyurethane resin adhesives were 0.85, 0.81. respectively.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.1
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• pp.89-93
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• 1983

This paper describes on experimental investigation into the heat dissipation of Diesel engine, placing emphasis on the variations of compression ratio and cooling water temperature. The engine used for this test was a vertical single-cylinder four-cycle type, having a direct injection. Engine performance and heat transfer rates was tested under the compression ratio 14.3 and 17.4. In this study, the results showed that output and transfer rates of engine decrease in accordance with the decrease of compression ratio. The effect of cooling water temperature and injection delay of fuel on the heat dissipation brings about the decrease of heat transfer rates from cylinder to cooling water.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.06a
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• pp.174-182
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• 1997

The technology of Semi-Solid Forging (SSF) has been actively developed to fabricate near-net-shape products using light and hardly formable materials. Generally, the SSF process is composed of slug heating, forming, compression -holding and ejecting step. After forming step in SSF, the slug is compressed during a certain holding time in order to be completely filled in the die cavity and be accelerated in solidification rate. The compression holding time that can affect microstructural characteristics and shape of products is important to make decision, where it is necessary to find overall heat transfer coefficient properly which has large effect on heat transfer between slug and die. This paper presents the procedure to predict compression holding time of obtaining the final shaped part with information of temperature and solid fraction for a cylindrical slug at compression holding step in closed-die compression process using heat transfer analysis considering latent heat by means of finite element method. The influence of the predicted compression holding time on microstructural characteristics of products is finally investigated by experiment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.199-203
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• 1995

The technology of Semi-Solid Forging (SSF) has been actively developed to fabricate near-net- shape products using light and hardly formable materials, the SSF process is composed of slug heating, forming, compression holding and ejecting step. After forming step in SSF, the slug is compressed during a certain holding time in order to be completely filled in the die cavity and be accelerated in solidification rate. The compression holding time that can affect mechanical properties and shape of products is important to make decision, where it is necessary to find overall hert transfer coefficeient properly which has large effect on heat transfer between slug and die. This paper presents the procedure to predict compression holding time of octaining the final shaped part with information of temperature and solid fraction for a cylindrical slug at compression hoiding step in closed-die compression process using heat transfer analysis considering latent heat by means of finite element method. The influence of the predicted compression hoiding time on mechanical properties of products is finally investigated by experiment.

• Journal of Hydrogen and New Energy
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• v.31 no.2
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• pp.259-264
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• 2020

In this study, comparison study has been performed between two-stage compression and a vapor-recompression refrigeration cycle and a liquefaction using LNG cold heat. When using a first method using two-stage compression and a refrigeration cycle, at least three compressors are required, however when using LNG cold heat, no compressor is required since carbon dioxide can be pumped after condensing with the heat exchange with -160℃ of LNG. Through this study, we can save more than one hundred million KRW annually by using LNG cold heat instead of using gas compression and refrigeration cycle.

• Journal of the Korea Furniture Society
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• v.11 no.1
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• pp.85-89
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• 2000

This study investigated the effect of steaming on fixation of compression set and the effect of these treatments on mechanical properties of heat-compressed wood specimens. To determine the effect of steaming after compression set, wood specimens were compressed for 100min at 180f and then steamed for 20-100min at $120^{\circ}C$. Swelling tests were used to evaluate recovery of compression set. Bending, compression, and Brinell hardness tests were carried out for evaluating mechanical properties. Compressed wood steamed for 100 min at $120^{\circ}C$ showed 1.9% recovery of set, increases in bending and compressive properties, and no hardness change. We concluded that almost complete fixation of compression set in wood can be achieved by steaming compressed wood.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.7
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• pp.585-590
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• 2012

The objective of this study is to investigate the performance of a two-stage compression heat pump system for district heating. The experimental setup of heat pump consists of compressor, condenser, evaporator, expansion device, intercooler, flash tank, oil separator and accumulator. The experimental evaluations on the two-stage compression cycle were carried out under various operating conditions which were heat source temperature, the degree of compressor inlet superheat, and intermediate pressure. The temperature ranges of unutilized energy as the heat source were used in the test conditions. As the heat source temperature increased from $10^{\circ}C$ to $30^{\circ}C$, the COP and heating capacity of the heat pump system increased by 22.6% and 45.8%, respectively. The performance of the two-stage heat pump system increased by 5.2% with the variation of the intermediate pressure in the same heat source temperature conditions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2386-2395
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• 1994

An experimental study on heat transfer and flow in compression molding of clss-B and A SMC(Sheet Molding Compounds) in a flat plate and a cross-sectional T-shape was carried out. The temperature was measured with thermocouples at two locations in the 4 layered SMC charge and pressure was measured at the center of the top mold during compression molding. Three different mold speeds, 15, 45, 50 mm/min and two different mold temperature, $130^{\circ}C{\;}and{\;}150^{\circ}C$ were used for compression molding experiments. Experiments with different colored SMC layers were used to study flow patterns at various compression stages. In oder to predict the pressure and load in SMC compression molding, slab method was used. The predicted values of pressure and load from the slab analysis were compared well with the measured data.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.451-456
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• 2005

The mathematical model for the heat exchangers of absorber and desorber is made in the elementary control volume method and the thermodynamic properties of working fluid. water/ammonia mixture. are calculated by some fundamental subroutines in RefProp 7.0 and flash subroutines made by authors The simulation results show that two-stage cycle has higher COP than single stage if temperature lift is high: the performance of single stage compression cycle can be improved by increase of absorber pressure. but the performance of two-stage compression cycle can not be improved in this way : the compressor discharging temperature of two-stage compression is much lower than that of single stage cycle. which is very important to the safety operation of CA heat pump. Major parameter comparison between the cycles at their optimal configurations is also given.

• Journal of the Korean Wood Science and Technology
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• v.39 no.4
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• pp.311-317
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• 2011

The mechanical properties of heat-compressed Radiata pine (Pinus radiata D.Don) by compression set were investigated. Heat-compression condition was temperature at $180^{\circ}C$ and press time for 60 minutes. The mechanical properties of heat-compressed wood increased with increasing compression set. Increase of the specific gravity has led to increase in mechanical properties. The maximum compression set of Radiata pine was investigated approximately 65%. It was almost same result with porosity 68% of Radiata pine in specific gravity 0.48.