• Journal of the Korean Geotechnical Society
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• v.29 no.9
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• pp.31-41
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• 2013

The use of energy pile foundation has increased for economic utilization of geothermal energy. In particular, coil-shaped ground heat exchanger (GHE) is preferred to the conventional U-shaped exchanger to ensure better efficiency of heat exchange rate. This paper presents a numerical and experimental study on the heat transfer behavior of PHC energy piles. Field thermal performance tests (TPTs) were conducted for the PHC energy piles installed in a partially saturated weathered granite soil deposit, in which two types of GHEs were considered: W and coil shaped GHEs. Besides, three-dimensional finite element analyses were also conducted, and the results were compared with the experimental results. According to the results of TPT and numerical analyses, the coil shaped GHE showed 10~15% higher heat exchange rate than the W type GHE in the PHC energy piles.

• Korean Journal of Remote Sensing
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• v.11 no.1
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• pp.65-80
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• 1995

Remote Sensing data with ancillary ground-based meteorological data provides the capalility of computing threeof the four surface energy balance components(i.e. net radiation, soil heat flux and sensible heat flux) at different spatial and temporal scales. As a result, this enablis the estimation of the remaining term, latent heat flux. One of the practical applications with this approach is to produce evapotranspiration maps over large areas. This results could estimate and reproduce areal evapotranspiration over large area as much as several hundred sequare kilometers. Moreover, some calculating simulations for the effects of the land use change on the surface heat flux has been made by this method, which is able to estimate evapotranspiration under arbitracy presumed condition. From the simulation of land use change, the results suggests that the land use change in study area can be produce the significant changes in surface heat flux. This preliminary research suggests that the future research should involve development of methods to account for the variability of meteorological parameters brought about by changes in surface conditions and improvements in the modeling of sensible heat transfer across the surface atmosphere interface for partical canopy conditions using remote sensing information.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.3
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• pp.220-230
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• 1992

Soil temperature is one of the important environmental factors which control all the physical, chemical and biological processes in soil including germination and root growth of plants and other organisms living in the soil ecosystem. Soil water and nutrient availability and mobility are temperature dependent. Soil temperature change is depended primarily upon energy exchange in soil surface, meteorological variance and physical properties of the soils which are closely related to heat transfer mechanism. In this study physical properties including bulk density, soil texture and organic matter content were measured and thermal diffusivity on the soils was calculated. Soil samples from the 66 meteorological stations under the Korea Meteorology were collected and the physical parameters were measured. To obtain relationship between thermal diffusivity and soil water content a heat probe thermal diffusivity measurement apparatus was designed and used in this experiment. According to the survey on soil physicsal properties on the 66 meteorological stations, the 52% of the surface soil texture were sandy loam and laomy sand or sand, 38% were loam and silty loam, and 10% were clay loam and silty clay loam. The bulk density which was closely related with thermal properties showed average of $1.41g/cm^3$ for sandy soils, $1.33g/cm^3$ for loam and silty loam soils, and $1.21g/cm^3$ for clay loam and silty clay loam soils. The apparent thermal diffusivity of the upper layer from 0 to 30cm ranged from 1.16 to $8.40{\times}10^{-3}cm^3/sec$ with average of $3.53{\times}10^{-3}cm^3/sec$. The apparent thermal diffusivities of the Jeju soils of which organic matter contents were high and the bulk densities were low were near $2{\times}10^{-3}cm^3/sec$. The thermal diffusivity of snow measured in Chuncheon ranged from 0.822 to $2.237{\times}10^{-3}cm^3/sec$. The damping depth calculated from the thermal diffusivity ranged from 5.92 to 13.65cm for daily basis and 124 to 342cm for yearly basis. The significant regression equation to estimate thermal diffusivity with bulk density and soil water content was obtained by the heat probe in laboratory.

• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.1
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• pp.53-66
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• 1980

The research work is concerned with the analytical and experimental studies on the heat transfer phenomenon around the underground concrete digester used for biogas production Systems. A mathematical and computational method was developed to estimate heat losses from underground cylindrical concrete digester used for biogas production systems. To test its feasibility and to evaluate thermal parameters of materials related, the method was applied to six physical model digesters. The cylindrical concrete digester was taken as a physical model, to which the model,atical model of heat balance can be applied. The mathematical model was transformed by means of finite element method and used to analyze temperature distribution with respect to several boundary conditions and design parameters. The design parameters of experimental digesters were selected as; three different sizes 40cm by 80cm, 80cm by 160cm and l00cm by 200cm in diameter and height; two different levels of insulation materials-plain concrete and vermiculite mixing in concrete; and two different types of installation-underground and half-exposed. In order to carry out a particular aim of this study, the liquid within the digester was substituted by water, and its temperature was controlled in five levels-35。 C, 30。 C, 25。 C, 20。C and 15。C; and the ambient air temperature and ground temperature were checked out of the system under natural winter climate conditions. The following results were drawn from the study. 1.The analytical method, by which the estimated values of temperature distribution around a cylindrical digester were obtained, was able to be generally accepted from the comparison of the estimated values with the measured. However, the difference between the estimated and measured temperature had a trend to be considerably increased when the ambient temperature was relatively low. This was mainly related variations of input parameters including the thermal conductivity of soil, applied to the numerical analysis. Consequently, the improvement of these input data for the simulated operation of the numerical analysis is expected as an approach to obtain better refined estimation. 2.The difference between estimated and measured heat losses was shown to have the similar trend to that of temperature distribution discussed above. 3.It was found that a map of isothermal lines drawn from the estimated temperature distribution was very useful for a general observation of the direction and rate of heat transfer within the boundary. From this analysis, it was interpreted that most of heat losses is passed through the triangular section bounded within 45 degrees toward the wall at the bottom edge of the digesten Therefore, any effective insulation should be considered within this region. 4.It was verified by experiment that heat loss per unit volume of liquid was reduced as the size of the digester became larger For instance, at the liquid temperature of 35˚ C, the heat loss per unit volume from the 0. 1m$^3$ digester was 1, 050 Kcal/hr m$^3$, while at for 1. 57m$^3$ digester was 150 Kcal/hr m$^3$. 5.In the light of insulation, the vermiculite concrete was consistently shown to be superior to the plain concrete. At the liquid temperature ranging from 15。 C to 350 C, the reduction of heat loss was ranged from 5% to 25% for the half-exposed digester, while from 10% to 28% for the fully underground digester. 6.In the comparison of heat loss between the half-exposed and underground digesters, the heat loss from the former was fr6m 1,6 to 2, 6 times as much as that from the latter. This leads to the evidence that the underground digester takes advantage of heat conservation during winter.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2002.04a
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• pp.25-29
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• 2002

대부분의 작물이 생육하기에 적합한 지온은 18-2$0^{\circ}C$정도이고 최고한계는 23-$25^{\circ}C$로 알려져 있으나, 여름철 온실내의 지온은 이보다 높으며 2001년 8월에 온실내의 지온을 계측해본 결과 표층으로부터 5-35cm 깊이의 평균 지온은 27-29.4$^{\circ}C$까지 상승하는 것으로 나타났다(김 등, 2001). 따라서 지중 냉각의 필요성이 인정되며, 정 등(1998)의 보고에 의하면 무처리시 지온 25.7$^{\circ}C$에 대하여 지하수 냉각으로 지온을 19-19.6$^{\circ}C$로 냉각해줄 경우 배추 수량이 8-11% 증수되었다. (중략)

• Journal of the Korean Solar Energy Society
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• v.36 no.3
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• pp.87-94
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• 2016

Earth tube system can be installed in many ways. However, performance data on earth tube system is still insufficient. Therefore, in this study seven design parameters of earth tube systems were chosen such as underground earth tube length, depth, tube thermal conductivity, thickness, radius, soil conditions, and fan type. And the change effects in the values of the seven parameters on earth tube exit temperatures and heat transfer rate were examined through Energyplus simulations.

• Journal of Environmental Impact Assessment
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• v.29 no.3
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• pp.219-229
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• 2020

This study evaluated the applicability of the convergence technology by deriving the optimum conditions about operating factors of electrical resistance heating to enhance the soil flushing effect on soil contaminated with bunker C oil in the coastal landfill area. As a result of the batch scale experiment, the flushing efficiency of the VG-2020 was higherthan that of the Tween-80, and the flushing efficiency increased by about 1.4 times at 60℃ compared to room temperature. As a result of the electrical resistance heating box experiment, soil temperature rose to 100℃ in about 40~80 minutes in soil with water content of 20~40%, and it was found that the heat transfer efficiency is excellent when the pipe-shaped electrode rod with STS 316 material is located in a triangular arrangement in saturated soil. In addition, it was confirmed that the interval between the electrode rods to maintain the soil temperature above 60℃ under the optimum conditions was 1.5 m, and the soil flushing box experiment accompanying electrical resistance heating showed TPH reduction efficiency of about 55% at 5 Pore Volume, and satisfied the Korean standard for the conservation of soil (less than TPH 2,000 mg/kg) at 10 Pore Volume.

• Journal of Life Science
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• v.20 no.1
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• pp.97-102
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• 2010

Streptomyces platensis YK-2, newly isolated from forest soil, produces transglutaminase (TGase), which catalyses an acyl transfer reaction between the primary grade amine and protein or $\gamma$-carboxyamide group of peptide bound glutamine residues. For a molecular genetic study of S. platensis, an effective transformation method was established by using a conjugal transfer of DNA from Escherichia coli to spores of actinomycetes. The highest transconjugation frequency of S. platensis was obtained on an MS medium containing 50 mM $MgCl_2$, using $5{\times}10^7\;E$. coli as a DNA donor and $1{\times}10^8$ spores without heat treatment as a host. We also identified that S. platensis contains a single attB site within an ORF encoding a pirin-homolog, and that its attB site sequence shows high homology to that of S. logisporoflavus. In addition, it was confirmed by phenotypic analyses of exconjugants that the introduction of heterologous DNA into the attB site of the S. platensis chromosome does not affect its morphological differentiation and TGase production.

• Journal of the Korean Geotechnical Society
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• v.33 no.2
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• pp.35-47
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• 2017

Thermal behavior of soils is mainly focused on thermal conduction, and the study of natural convection is very limited. Increase of soil temperature causes natural convection due to buoyancy from density change of pore water. The limitations of the analysis using fluid dynamics for natural convection in the porous media is discussed and a new numerical analysis is presented for natural convection in porous media using THM governing equations fully coupled in the macroscopic view. Numerical experiments for thermal probe show increase in the uncertainty of thermal conductivity estimated without considering natural convection, and suggest appropriate experimental procedures to minimize errors between analytical model and numerical results. Burial of submarine power cable should not exceed the temperature changes of $2^{\circ}C$ at the depth of 0.2 m under the seabed, but numerical analysis for high permeable ground exceeds this criterion. Temperature and THM properties of the seafloor are important design factors for the burial of power cable, and in this case effects of natural convection should be considered. Especially, in the presence of heat sources in soils with high permeability, natural convection due to the variation of density of pore water should be considered as an important heat transfer mechanism.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1994.06a
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• pp.11-26
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• 1994

Crown gall of stonefruit and nut trees is one of the very few plant diseases subject to efficient biological control. The disease is caused by the soil-inhabiting bacteria Agrobacterium tumefaciens and Agrobacterium rhizogenes and the original control organism was a non-pathogenic isolate of A. rhizogenes strain K84. Control is achieved by dipping planting material in a cell suspension of strain K84 which specifically inhibits pathogenic strains containing a nopaline Ti plasmid. Because the agrocin 84-encoding plasmid (pAgK84) is conjugative, it can be transmitted from the control strain to pathogenic strains which, as a result, become immune to agrocin 84 and cannot be controlled. To prevent this happening, the transfer genes on pAgK84 were located and then largely eliminated by recombinant DNA technology. The resulting construct, strain K1026, is transfer deficient but controls crown gall just as effectively as does strain K84. Field data from Spain confirm that pAgK84 can transfer to pathogenic recipients from strain K84 but not from strain K1026. The latter has been registered in Australia as a pesticide and is the first genetically engineered organism in the world to be released fro commercial use. It is recommended as a replacement for strain K84 to prevent a breakdown in the effectiveness of biological control of crown gall. Several reports indicate that both strains K84 and K1026 sometimes control crown gall pathogens that are resistant to agrocin 84. A possible reason for this is that both strains produce a second antibiotic called 434 which inhibits growth of nearly all isolates of A. rhizogenes, both pathogens and non-pathogens. Crown gall of grapevine is caused by another species, Agrobacterium vitis. It is resistant to agrocin 84 and cannot be controlled by strains K84 or K1026. It is different from other crown gall pathogens in several characteristics, including the fact that, although a rhizosphere coloniser, its also lives systemically in the vascular tissue of grapevine. Pathogen free propagating material can be obtained from tissue culture or, less surely, by heat therapy of dormant cuttings. A number of laboratories are searching for a biocontrol strain that will prevent, or at least delay, reinfection. A non-pathogenic A. vitis strain F/25 from South Africa looks very promising in this regard.