• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.155-160
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• 2005

To purpose of this research is to develop the numerical model for simulating performance of ground heat exchanger with high prediction accuracy. This paper describes the development of a numerical model that simulates the heat transfer between ground and circulation water in ground heat exchanger. Furthermore, we propose the estimating technique of soil properties, such as thermal conductivity, heat capacity and hydraulic conductivity, based on ground investigation. Comparison between experiment and numerical analysis based on the model developed above was conducted under the condition of the experiment in 2004. The result of analysis agreed well with the experimental result.

• Journal of the Korean Geotechnical Society
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• v.31 no.1
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• pp.15-24
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• 2015

This paper presents the results of a reduced-scale physical model investigation into the effect of drilling fluid with different mix designs for bore hole collapse prevention. The bore hole collapse prevention mechanism for the bentonite based drilling fluid was first discussed together with the effect of conditioning with different additives on engineering characteristics of bentonite based drilling fluid. Reduced-scale model tests were then carried out considering field procedures for cases with a decomposed granitic soil with 20% fines and a sand with various drilling fluids with different mix designs. The results indicated that the addition of polymer to the bentonite based drilling fluid decreases the amount of drilling fluid injected, the drilling fluid infiltration thickness and increases the final depth of excavation. Also revealed is that the effect of polymer on the performance of drilling fluid is more pronounced in the decomposed granite soil with 20% fines than the sand. Practical implications of the findings from this study are discussed in great detail.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.6
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• pp.76-85
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• 2009

This study was carried to select the proper vegetation base materials which improve soil quality in abandoned coal mine areas. Also, we aimed at the feasibility of the direct seeding method without soil molding for the ecological restoration in those areas. We set total eight plots within the study site established on an abandoned coal mine area near Taebaek city, Gangwon province in April 2006. The plots were classified as two groups(straw mats mulching and no mulching), and the four treatments (C; control, MI; microbial innoculation, WC; wood chip, OF; organic fertilizer) were applied in each two groups for the soil conditioning. The survival of Pinus densiflora was highest among other species(Betula platyphylla var. japonica, Amorpha fruticosa and Arundinella hirta). For the non straw mat, the survival rate of Pinus densiflora seedlings was highest in the WC treatment($1,756trees/m^2$). For the straw mat, survival rate of Pinus densiflora seedlings was also highest in the WC treatment ($1,622trees/m^2$). In addition, for the non straw mat, the height growth of Pinus densiflora seedling was highest in the OF treatment($12.4{\pm}3.9cm$). For the straw mat, the height growth of Pinus densiflora seedling was also highest in the OF treatment($18.7{\pm}5.3cm$). In general, organic fertilizer treatment with the straw mat was most effective for seedling growth. Also, we suggested that the direct seeding method without soil molding could be sufficiently possible for revegetating abandoned coal mine, Korea.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.6
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• pp.355-366
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• 2009

In the present study, fuel cell driven ground source heat pump system is applied to a large community building and performance of the heat pump system is computationally analyzed. Conduction heat transfer between brine pipe and ground is analyzed by TEACH code to predict the performance of heat pump system. Predicted COP of the heat pump system and the energy cost were compared with variation of the location of the objective building the water saturation rate of soil and the driven powers of heat pump system. Significant reduction of energy cost can be accomplished by employing the fuel cell driven heat pump system in comparison with the late-night electricity driven system. It is due to the low electricity production cost of fuel cell system and the application of recovered waste heat generated during electricity production process to the heating of large community building.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.879-884
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• 2006

Jinan Poonghyeol in Chonbuk province Is famous for emitting cool air in summer and warm air in winter. Cause for these phenomena is studied by measuring temperature, humidity and air velocity of several locations around Jinan Poonghyeol Temperature variations under the ground are also measured. Analyzing data compiled from July 21, 2005 through May 26, 2006, it is presumed that storage effect of rocks and soil in this area and buoyance effect are the main causes for this mysterious natural air-conditioning phenomena.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.12
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• pp.1218-1226
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• 2004

This paper presents thermal behaviors and performances of a fresh air load reduction system by using earth tube system combined with air-heated solar collector. The earth tube system reduces a fresh air load by heat exchange with soil throughout the year. In the previous experimental research, it was clarified that the earth tube system was very useful as a fresh air load reduction system. However, since outlet temperature of the fresh air which was heated by earth tube system was below 15$^{\circ}C$ in winter, it is not suitable to introduce the fresh air into the place of residence directly. Therefore, a simulation model using the simple heat diffusion equation was used to examine a rising effect of outlet air temperature in winter by combining with air-heated solar collector. An improvement of annual performance by control of operation is also quantitatively examined. In conclusion, it is confirmed that its performance is improved by control of operation throughout the year and outlet air temperature rose by combining with air-heated solar collector.

• Korean Journal of Medicinal Crop Science
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• v.20 no.4
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• pp.217-221
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• 2012

This research was conducted to investigate the influence of various organic substrates on growth and yield of ginseng seedling grown organically in the closed plastic house. The pH and EC of substrates used for organically ginseng cultivation ranged 5.93~6.78 and 0.03~0.15 dS/m respectively. The concentrations $NH_4$-N and $NO_3$-N respectively was 14.01~68.63 mg/L, 5.60~58.83 mg/L. The average quantum of the closed plastic house was range from 10 to 16% of natural light. In July and August, the maximum temperature of the closed plastic house did not exceed 30 and the average temperature was maintained within 25 lower than the field because air conditioning ran. The PPV-1 and PPV-2 bed soil substrates produced higher stem length, stem diameter, shoot fresh weight and leaf area than those of conventional culture. In PPV-2 bed soil substrates, root fresh weight and root diameter was the highest. The root fresh weight of PPV-2 bed soil substrates in closed plastic house was maximum 25% heavier than the conventional cultivation. The results of this experiment will be utilized for making new substrate application for organic ginseng culture in the plastic house.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.3
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• pp.323-345
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• 2019

It is essential to predict ground conditions ahead of a tunnel face in order to successfully excavate tunnels using a shield TBM. This study proposes a forward prediction method for a mixed soil ground and/or a ground containing core stones by using electrical resistivity and induced polarization exploration. Soil conditioning in EPB shield TBM is dependent upon the composition of mixed soils; a special care need to be taken when excavating the core-stoned soil ground using TBM. The resistivity and chargeability are assumed to be measured with four electrodes at the tunnel face, whenever the excavation is stopped to assemble one ring of a segment lining. Firstly, the mixed ground consisting of weathered granite soil, sand, and clay was modeled in laboratory-scale experiments. Experimental results show that the measured electrical resistivity considerably coincides with the analytical solution. On the other hand, the induced polarization has either same or opposite trend with the measured resistivity depending on the mixed ground conditions. Based on these experimental results, a method to predict the mixed soil ground that can be used during TBM tunnel driving is suggested. Secondly, tunnel excavation from a homogeneous ground to a ground containing core stones was modeled in laboratory scale; the irregularity of the core stones contained in the soil layer was modeled through random number generation scheme. Experimental results show that as the TBM approaches the ground that contains core stones, the electrical resistivity increases and the induced polarization fluctuates.

• Korean Journal of Organic Agriculture
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• v.14 no.4
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• pp.433-443
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• 2006

With treatment of Kitosan, Wood vinegear and EM(effective microoganism) which farmers call it as substance in fertilizing, conditioning and disease control substances, authors in vestigated on microorganisms change in soil and ealy growth characteristics of tomato. The results were summarized as follows: Among foliar application of kitosan, wood vinegear and EM(effective microoganism) treatments diluted by chitosan 500 times solution level was effective considering growth of tomato as compared other dilutions and control plot. Change of microorganism number in the soil for cultivation of tomato was increased with microorganism treatment plot as compared with control plot. Specially chitosan 500 times solution level showes the most significant effect.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.869-872
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• 2008

On this study, the Control of Temperature is specified on the view of indoor comfort and building energy consumption. It is estimated by Dynamic heat load simulation which has the factors of insulation method and the soil thickness of the green roof system. The fact that the model which has no insulation has the greatest effect of dropping high temperature and the cooling load decrease is confirmed.