• 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 Korea Institute of Military Science and Technology
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• v.9 no.2 s.25
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• pp.87-95
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• 2006

The performance of a microwave missile seeker and radar operating in an air-to-air look-down mode is strongly influenced by the presence of ground clutter In order to correctly account for the effects of ground clutter, it is required to develop a model capable of representing clutter characteristics as a function of range and/or frequency. In this paper, a program to estimate the clutter reflectivity for various ground conditions is developed, using the actually measured data and the data available from open literatures. In addition, clutter characteristics measured for various ground conditions such as sea, agricultural area, urban city and industrial area through the captive flight tests are presented.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.7
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• pp.658-666
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• 2004

In this paper, a two-dimensional transient ground-coupled numerical model for slab-on-grade foundation is developed and integrated into EnergyPlus. A validation analysis is first presented to ensure that for the developed building foundation heat transfer module is properly implemented within EnergyPlus. Then, the predictions from the developed model are compared to those obtained from the simplified building foundation model currently used in EnergyPlus. The results show that the developed foundation heat transfer module accounts better for the effects of the ground thermal mass attributed to the ground than the simplified foundation model currently used in EnergyPlus.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.135-138
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• 2007

A novel technique to estimate the dielectric constant of ground material by means of air launching GPR is proposed. The technique is an application of SAR algorithm. A laboratory experiment was conducted to examine the technique.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.2
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• pp.95-102
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• 2011

A ground loop heat exchanger in a ground source heat pump system is an important unit that determines the thermal performance of a system and its initial cost. A proper design requires certain site specific parameters, most importantly the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. This study was performed to investigate the effect of some parameters such as borehole lengths, various grouting materials and U tube configurations on ground effective thermal conductivity and borehole thermal resistance. In this study, thermal response tests were conducted using a testing device to 9 different ground loop heat exchangers. From the experimental results, the length of ground loop heat exchanger affects to the effective thermal conductivity. The results of this experiment shows that higher thermal conductivity of grouting materials leads to the increase effective thermal conductivity from 22 to 32%. Also, mounting spacers have increased by 14%.

• The Journal of the Acoustical Society of Korea
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• v.3 no.1
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• pp.3-8
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• 1984

By one dimensional acoustic transmission from ground to air, the author has derived the level of sound caused by earthquakes. He has also tried to assign proper values of ground acceleration to the modified mercalli intensity scale and thence earthquake sound level to the intensity scale has been deduced as L\sub M/ = 79.6+6.0M, dB, where M is the earthquake magnitude in the modified Mercalli intensity scale.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.4 no.1
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• pp.6-17
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• 1975

For a periodic variation of the flue gas temperature the heat conduction through the Ondol floor was analysized. Also the heat loss to the ground was estimated. The floor thermal capacity, as a function of the floor thickness, has strong influence on the time lag of the temperature variation. It is an important design parameter for intermittent heating. Even for the steady periodic variation, there was significant heat loss to the ground below the Ondol floor.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.8
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• pp.741-746
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• 2007

In this paper, we propose an accuracy analysis method for air-to-ground weapon delivery. The lethality, which is one of the most important factor to evaluate combat effectiveness of a fighter, depends on the capability to improve the accuracy of the conventional weapon delivery. We present error elements which affect the error analysis for air-to-ground weapon delivery from the initial design phase to the final validation phase. And we introduce an accuracy analysis method to reflect the error elements and to evaluate them quantitatively. We assume zero bias-error and consider random error for the weapon delivery accuracy analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.517-522
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• 2017

Launch Acceptability Region(LAR) is a region for an aircraft which carries air-to-ground guided bombs to enter such that it can successfully hit the target. LAR should consider the release condition of an aircraft, impact condition for targets, and environmental condition of atmosphere. In this paper, LAR algorithm was developed using the database of many simulations which were varied by inputs, such as the release, impact, and environmental conditions. The algorithm was tested through the direct simulation results, and found that it was suitable to apply as LAR for air-to-ground guided bomb.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.6
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• pp.337-344
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• 2010

Good plant-growth conditions can be achieved by means of using greenhouses. One of the main issues in greenhouse cultivation is energy savings through the development of high efficient heating and cooling system. GSHPs are one of the recommended systems to cope with this pending need. The aim of this study is to investigate the heating performance of ground source multi-heat pump system installed in a greenhouse under part load conditions. Daily average heating COP of the heat pump unit was very high by at least 7.4, because of relatively large condenser, evaporator, and mass flow rate through ground loop heat exchanger. However, the system COP, overall heating coefficient of the performance of the system with heat pump unit and GLHX, decreased drastically due to relatively large power consumption of circulating pump under part load condition. It is suggested that the technology to enhance the performance of the ground source multi-heat pump system for a greenhouse under part load conditions should be developed.