• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.27 no.1
• /
• pp.31-38
• /
• 2015

Geothermal heat pump (GHP) systems have become an efficient alternative to conventional cooling and heating methods due to their higher energy using efficiency. These systems use the ground as a heat source in heating mode operation and a heat sink in cooling mode operation. The aim of this study is to evaluate the heating performance of the GHP system for a residential building ($420m^2$) in Ulaanbaatar, Mongolia. In order to demonstrate the feasibility of a sustainable performance of this system, we installed the water-to-water geothermal heat pump with ten vertical ground heat exchangers and measured operation parameters from October 19, 2013 to March 26, 2014. The results showed that the entering source temperature of brine from the ground heat exchangers was in a range of the design target temperature of $-10^{\circ}C$ for heating. For total values of the representative results, the ground heat exchangers extracted heat of 53.51 MWh from the ground. In addition, the GHP system supplied heat of 83.55 MWh to the building and consumed power of 30.27 MWh. Consequently, the average heating seasonal performance factor ($SPF_h$) of the overall system was evaluated to be 2.76 during the measurement period of the heating season.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.12
• /
• pp.1829-1836
• /
• 2010

The district heating system distributes the heat generated from a cogeneration plant to wider locations. In this process, the district heating pipe (DHP) is subjected to internal and external loadings. The internal loadings are generally caused by the operating conditions such as water temperature and internal pressure. Frictional interactions between the pipes and the soil contribute to the external loadings. Thus, investigation of the mechanisms of failure of DHPs will help to guarantee both mechanical stability and heating efficiency. In this study, we investigate the local buckling of DHPs using limit state design (LSD). Two methods are considered: the use of the limit state for the width-thickness ratio and the use of the limit state for the strain. The results are used to confirm that the DHP is stable under local buckling. Finally, we suggest a minimum preheating temperature for avoiding local buckling.

• Applied Microscopy
• /
• v.31 no.4
• /
• pp.315-323
• /
• 2001

In situ TEM heating experiments utilizing kaolinite powder samples result in the following facts. (1) The water recirculation system adopted in the Gatan's heating holder is required to prevent specimen drift above $500^{\circ}C$. (2) Since the degree of phase changes depends on the thickness of powders below $600^{\circ}C$, examinations of both thin and thick specimens are required. (3) Sample preparation using Mo-grids is required for TEM heating experiments above $900^{\circ}C$. At these temperature ranges the effect of heating rate and holding time on the phase transition process increases drastically, so that a programmed temperature control is required. (4) TEM heating experiments of the embedded powders by epoxy for the cross-sectional view was limited due to the severe epoxy movement during heating above $300^{\circ}C$. Better methods of sample preparation are required to overcome this problem.

• Journal of the East Asian Society of Dietary Life
• /
• v.23 no.2
• /
• pp.203-210
• /
• 2013

In this study, cod bone were used as the main ingredient of a stock that can be eaten with Korean dried noodles. The stock was produced with heating for 30, 40, 50, 60, or 70 minutes using high-pressure extraction methods. Moisture content, chromaticity, pH, sugar content, salinity, mineral contents, quantitative analysis, and overall acceptance were studied to determine the optimal heating time. In our result, S1 the showed highest water contents 98.10%, while S5 showed the lowest moisture content (97.47%). There were no significant difference in pH between samples, while salinity and sugar content increased with increases in heating time. In terms of mineral contents, sodium and potassium showed proportional difference with increases in heating time, however, magnesium, calcium, and iron did not change. The results from a quantitative analysis test showed that transparency, fishy smell, delicate flavor, savory flavor, salt taste, and umami taste became stronger with increases in heating time increase. From the above results, the overall taste of the stock increases with increases in high-pressure heating time. Specifically, S4 high-pressure heating scored the highest on appearance, flavor, taste, after-taste, and overall acceptance. Thus, 60 minutes of high-pressure heating time is most desirable when producing stock with cod bones as a main ingredient.

• Journal of Welding and Joining
• /
• v.26 no.4
• /
• pp.79-84
• /
• 2008

Use of sheet metal structure is increased in various fields such as automobile, aerospace and communication equipment industry. When this structure is welded, welding distortion is generated due to the non-uniformity of temperature distribution. Recently welding distortion becomes a matter of great importance in the structure manufacture industry because it deteriorates the product's quality by bringing about shape error. Accordingly many studies for solving the problems by controlling the welding distortion are being performed. However, it is difficult to remove all kinds of distortion by welding process, though various kinds of methods for reducing distortion are applied to production. Consequently, straightening process is operated if the high precision quality is requested after welding. The local heating method induces compression plastic deformation by thermal expansion in the heating stage and then leaves constriction of length direction in the cooling stage. Accordingly, in the case of sheet metal structure, straightening effect is expected by heating for the part of distortion. This study includes numerical analysis of straightening effect by the local heating method in distortion comes from production of welded sheet metal structure. Particularly straightening effect followed by dimensions of heating area is analyzed according to the numerical analysis. The numerical analysis is performed by constructing 3-dimensional finite element model for 0.4mm stainless steel-sheet metal. Results of this study confirm that straightening effect changes as heating area increases and the optimum value of heating area that proves the maximum straightening effect exists.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.12 no.1
• /
• pp.17-22
• /
• 2016

It is very important to obtain a out-of season production in horticultural greenhouses corresponding with higher crop prices. A ground source heat pump system has been highly spotlighed as an energy efficient heating system for the greenhouse. This paper investigated the operating cost of the ground source heat pump system with the variation of generating temperature and designing methods for heating system of the greenhouse. Even though the COP of the ground source heat pump system decreased with an increment of generating temperature in heating mode, the operating cost could be reduced. By adopting the high temperature heat pump system and heat storage tank, it could be achieved to save energy and reduce the operating time of auxiliary oil heating system for producing good plant-growth in the greenhouse.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.27 no.3
• /
• pp.268-279
• /
• 2007

The reliability of cold-bonding repair technique of carbon-fiber reinforced plastics (CFRP) laminates, often used as a temporary repair for the airplane maintenance, has been evaluated during cyclic loading and localized heating by nondestructive methods. Major concern was given to the evolution of damage after repair in the form of delaminations due to localized heating and cyclic loading combined. An area of interest both on the specimen repaired by cold-bonding and the specimen without repair where delaminations were induced by localized heating and cyclic loading was monitored by acoustic emission (AE) testing and further examined by pitch-catch low-frequency bond testing, and pulse-echo high-frequency ultrasonic testing. The results showed that the reliability of cold-bonding repair would be significantly reduced by the localized heating and cyclic loading combined rather than by the cyclic loading only. AE monitoring appeared to be an effective and reliable tool to monitor the integrity of temporarily repaired CFRP laminates in terms of the structural health monitoring (SHM) philosophy.

• The Journal of Sustainable Design and Educational Environment Research
• /
• v.12 no.2
• /
• pp.61-70
• /
• 2013

As the existing school building power consumption is expressed by total power consumption, in the view of energy saving is disadvantage. The the power consumption of school building is divided as cooling, heating, lighting and others. The cooling power consumption, heating power consumption, lighting power consumption can be calculated using real total power consumption that gained from Korea Electric Power Corporation(KEPCO). The power consumption for cooling and heating can be calculated using heat transmittance, wall area and floor area, and for lighting is calculated by artificial lighting calculation. but this calculation methods is difficult for laymen. This study was carried out in order to establish the regression equation for cooling power consumption, heating power consumption, lighting power consumption and other power consumption in school building. In order to verify the validity of the regression equation, it is compared regression equation results and calculation results based on real power consumption. As the results, difference between regression result and calculation results for cooling and heating power consumption showed 0.6% and 3.6%.

• Journal of Korean Academy of Nursing
• /
• v.42 no.4
• /
• pp.579-588
• /
• 2012

Purpose: The purpose of this study was to identify the effects of heating on the non-affected hand on blood flow velocity, wound healing, and pain for hand microsurgery patients. Methods: This study was designed using the nonequivalent control group pretest-posttest design. Thirty-nine patients were assigned either to the experimental group (20 patients) or control group (19 patients). Data were analyzed with $x^2$-test, Fisher's exact test, t-test, and repeated measure ANOVA using SPSS/WIN 17.0 program. Results: After treatment in this program, blood flow velocity (F=5.13, p=.008) and wound healing (F=4.11, p=.020) improved significantly in the experimental group compared to the control group. But there was no significant improvement in pain in the experimental group compared to the control group (F=2.40, p=.097). Conclusion: Based upon these results, the non-affected side hand heating was recommended as an independent nursing intervention for the patients who need improvement in blood flow velocity and wound healing such as patients who have microsurgery. As the heating was effective even when applied on the non-affected side, it is the applicable to patients who cannot tolerate any therapy on affected side.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.10a
• /
• pp.315-318
• /
• 2004

The Advantages of hot machining are the reduction of cutting forces, tool wear, and the increase of material removal rates. In this study, a hot-machining characteristics of milling by CBN tip was exprimentely analyzed, and the influence of the surface temperature and the depth of cut on the tool life were investigated. The selection of a heating method for obtaining ideal temperature of metals in machining is important. Faulty heating methods could induce unwanted structural changes in the workpiece and increase the cost. This study uses gas flame heating. It is obtained that tungsten carbide-alloyed has a recrystallisation temperature range of $800-1000^{\circ}C$ which is the high heating temperature that might induce unwanted structural changes. If it is performed at temperatures higher than $800^{\circ}C$ in machining, the possibility of unwanted structural changes and the increased wear of tool can be shown. Consequently, in hot machining of tungsten carbide-alloy, this study has chosen $400^{\circ}C-600^{\circ}C$ because the heating temperature might be appropriate in view of the cost and workpiece considerations. The results of this study experimentally shows a new machining method for tungsten carbide-alloyed that decreases the wear rate of machining tools