• Journal of the Korean Solar Energy Society
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• v.29 no.5
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• pp.88-97
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• 2009

In these days, it attracts our attention to create a green outdoor environment around the building block in urban area. Green space and permeable ground covering are increased by laws and regulations. According to these trends, variety researches for improving outdoor environment are accomplished at this moment. However, the problems for outdoor environment such as heat island effect and air contaminant in urban area are still reported. The purpose of this study is to examine the variables to affect the formation of outdoor thermal environment by quantitative analysis. As a initial study, in this paper, the effect of ground composition on changes of surface temperature and heat flux in multi-residential building were analyzed by field measurement and numerical simulation. Through field measurement, the surface temperature and heat flux of artificial ground in multi-residential building in Suwon city were measured. The result showed that the surface temperature was decreased by about $20^{\circ}C$ with afforestation of artificial ground compared with those of concrete covering. Moreover, the inner temperature of artificial ground was changed as same behaviors of outdoor temperature changes to depths of 20cm. In simulation, the effect of soil types and depth of artificial ground on the changes of the surface temperature and heat flux were analyzed. As results, the natural soil ground was more effective against lowering the surface temperature than any other cases in the analyzed cases.

• KIEAE Journal
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• v.14 no.2
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• pp.29-36
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• 2014

The ground source heat pump (GSHP) system has attracted much of attention, because of its stability of heat production and the high efficiency of the system. Performance of the heat exchanger is dependent on the soil temperature, the ground thermal conductivity, the operation schedule, the pipe placement and the design temperature. However, in spite of the many variables of these systems, there have been few research on the effect of the systems on system performance. In this study, analysis of the heat exchange rate according to soil temperature and grout material was conducted by numerical simulation. Furthermore, the heat distribution around the ground heat exchanger was presented on the different conditions of grout and underground temperature by the simulation.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.16 no.4
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• pp.24-30
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• 2020

Ground source heat pump (GSHP) systems are actively introduced as cooling and heating conditioning systems of buildings due to annual stable performance and easily maintenance. However, ground temperature imbalance is occurred when the GSHP is used for a long period. Therefore, in this study, we proposed the operation method of the system that considered the recovery time of heat source temperature. The entering water temperature (EWT) and heat exchange rate (HER) were comparatively analyzed according to the continuous and intermittent operation. Furthermore, the underground thermal environment was evaluated by numerical analysis model. As the result, the intermittent operation was a maximum of 12.3% higher HER during the heating period than the continuous operation. In addition, the overall ground heat source temperature at the intermittent operation was higher than it at the continuous operation.

• International Journal of Air-Conditioning and Refrigeration
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• v.16 no.4
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• pp.109-116
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• 2008

Ground temperature restoration characteristics are the crucial factors to evaluate whether a ground source heat pump system can keep long time steady operation. They are mainly dependent on soil thermal properties, layout of pile group, operation/shutoff ratio, cooling/heating load, thermal imbalance ratio and so on. On the one hand, several types of vertical pile foundation heat exchangers are intercompared to determine the most efficient one by performance test and numerical method. On the other hand, according to the layout of pile group of a practical engineering and running conditions of a GSHP system in Shanghai, the temperature distribution during a period of five years is numerically studied. The numerical results are analyzed and are used to provide some guidance for the design of large-scale GSHP system.

• Journal of the Korean Society of Systems Engineering
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• v.6 no.1
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• pp.41-46
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• 2010

The ground high/low temperature test objective is to check the normal ground operation of FA-50 aircraft in the extreme ground ambient conditions. The aircraft was exposed in climatic conditions of the basic climatic category according to the MIL-HDBK-310. For verified normal operation in the extreme high temperature, the high temperature test was performed in the hot regional type conditions and accentuated solar radiation heat. This test was performed at the test chamber in ADD where is in Haemi. This paper was described about the test procedure of FA-50 high/low temperature including preparation, testing and results.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.63-65
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• 2003

The purpose of the study is to produce the surface ground temperature diagnostically using surface EBM with the use of GRID model in Geographic Information Systems (GIS). Certain characteristics have been analyzed for local slope effect, coastal effect and influence of high orographic aspect on the surface ground temperature. We present discussions on the meteorological responsibility for their temperature. The derived surface ground temperatures can be provided for comparison with those from satellite-based observ ation.

• Asian Journal of Atmospheric Environment
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• v.10 no.4
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• pp.179-189
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• 2016

Here we evaluated the effect of using water retentive pavement or WRP made from fly ash as material for main street in a real city block. We coupled computational fluid dynamics and pavement transport (CFD-PT) model to examine energy balance in the building canopies and ground surface. Two cases of 24 h unsteady analysis were simulated: case 1 where asphalt was used as the pavement material of all ground surfaces and case 2 where WRP was used as main street material. We aim to (1) predict diurnal variation in air temperature, wind speed, ground surface temperature and water content; and (2) compare ground surface energy fluxes. Using the coupled CFD-PT model it was proven that WRP as pavement material for main street can cause a decrease in ground surface temperature. The most significant decrease occurred at 1200 JST when solar radiation was most intense, surface temperature decreased by $13.8^{\circ}C$. This surface temperature decrease also led to cooling of air temperature at 1.5 m above street surface. During this time, air temperature in case 2 decreased by $0.28^{\circ}C$. As the radiation weakens from 1600 JST to 2000 JST, evaporative cooling had also been minimal. Shadow effect, higher albedo and lower thermal conductivity of WRP also contributed to surface temperature decrease. The cooling of ground surface eventually led to air temperature decrease. The degree of air temperature decrease was proportional to the surface temperature decrease. In terms of energy balance, WRP caused a maximum increase in latent heat flux by up to $255W/m^2$ and a decrease in sensible heat flux by up to $465W/m^2$.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.198.2-198.2
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• 2010

In this study, the COP variation with the duration of Ground Source Heat Pump (GSHP) systems operation was analyzed by experiment. This experimental facility was installed in residential house as a back-up device of solar thermal heating system. The capacity of heat pump is 2.5 kW with a vertical bore hole of 150m depth. The COP of GSHP is varied, depending on the ground temperature which is used as a heat source. The ground heat source temperature influencing heating COP is the soil or rock temperature which adjoin with geo-source heat exchanger. This temperature is decreased rapidly according to the operation duration of heat pump. As a result, COP of GSHP is decreased to 3 in one hour of continuous operation time.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.3
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• pp.339-348
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• 1999

A computer model was developed in order to predict the temperature distribution and the performance of the vertical tube-in-tube ground coil heat exchanger. This model has been validated by experimental results conducted by ORNL. The heat exchanger performance with the variation of the length is calculated and compared. As results, the heat exchanger performance is proportional to the length but the performance per unit length decreases. The minimum performance of 70m - PVC heat exchanger during cyclic operation for a week is obtained 20,054kJ/h for cooling operation and 13,915kJ/h for heating operation. And minimum temperature difference is $4.64^{\circ}C$ for cooling operation and $2.64^{\circ}C$ for heating operation. In each case, it is noted that the temperature difference between the pipe and the far-field occurs within 0.8m from the heat exchanger.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.437-440
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• 2005

We examined the relationship between the 50m temperature estimated by remote sensing sea surface temperature (SST) and fishing ground (squid fishing ground) detected by nighttime visible channel defense meteorological satellite program (DMSP) I operational linescan system (OLS) images in the East/Japan Sea during 1993-2000. The results are as follows: The numbers of nighttime fishing boat were distributed the highest in October, and the lowest in April during this study. A nighttime fishing grounds have concentrated in the East Korea Warm Current region, coastal regions of Honshu Island, and Polar front region. Fishing grounds have distributed $11-18^{\circ}C$ of estimated 50m temperature from the satellite data. Relationship between estimated 50m temperature and the distributed fisheries boats showed that the north boundaries of fishing grounds have distributed the temperature of below $12^{\circ}C$ from 1996 to 2000 and that of $13-15^{\circ}C$ during 1993-1995 and 1997-1999. Stable fishing grounds appeared near the Korea/Tsushima Strait from January to March. The center of fishing grounds in spring (April-Jun) have moved to the northward than that in winter, and variations appeared largely in winter. In summer (July-September), center of fishing grounds have formed near the Uleung Island in the south east coast of Korea, and in autumn maximum fishing ground appeared in October, the fishing ground southward from November.