• Geophysics and Geophysical Exploration
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• 제18권3호
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• pp.105-114
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• 2015

A long-term resistivity monitoring system has been developed for saturated cores in room temperature and humidity condition. A 3-channel water-pump continuously drops the water onto the top of saturated core sample surrounded by shrinkable tube as well as on the paper filters of the electrodes at both sides of the core sample, by which one can monitor the resistivity changes with maintaining full saturation of the rock core for a week or longer. Monitoring the resistivity changes has been performed with 3 kinds of rock samples including biotite gneiss, andesitic tuff, and shale for 9 days using the system. Consequently, it is proposed two hypothesis that conversion speed of temperature coefficient has close relation to the thermal properties of the rock sample and that the ratio of resistance between dry and saturated conditions for a rock sample can be related to the effective porosity of the sample. The ratio between dry and saturated resistance for the three rock types are 48, 705, and 2, while effective porosity was 3.7%, 3.3%, and 13.0%, respectively.

• Journal of Bio-Environment Control
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• 제14권3호
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• pp.182-189
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• 2005

This research was conducted to determine physical properties of four root media, peatmoss + vermiculite (1:1, v/v; PV), peatmoss + composted rice hall (1:1, PR), peatmoss + composted saw-dust (1:1 : PS) and peatmoss + composted pine bark (1:1 PB), as influenced by incorporation rate of Stock-sorb C (STSB). Each root medium containing STSB was packed in 22 cm diameter plastic pot and the physical properties were determined at 5 weeks after packing. As incorporation rate of STSB were elevated, total porosity increased in PV, PS and PB media with statistical differences at $5{\%}$ level. Those also resulted in increase of container capacity in PS and PB media, but statistical differences were not observed in PV and PR media. Elevated incorporation rate of STSB in PV, PS and PB media resulted in increase of air space with statistical differences. Trends in air space of the three root media showed a linear as well as quadratic responses to STSB contents of media. As incorporation rate of STSB increased, more water was retained in four root media at the soil moisture tension of 4.90 kPa, 9.81 kPa, 29.4 kPa and 1.5 MPa. The amount of water retained in PS medium was the highest at the moisture tension at 29.4 kPa and 1.5 MPa followed by PB, PR and PV medium. These results indicated that elevation of incorporation rate of STSB to various root media increased moisture retention capacity, but did not increase the available water holding capacity.

• Journal of Korean Society of Forest Science
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• 제102권2호
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• pp.255-263
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• 2013

This study was carried out to evaluate degradation status of forest trails by analysis of soil physical and chemical properties in Mt. Jiri area of Gyeongnam province. Soil texture was loam in the forest area and sandy loam in the forest trails. Soil bulk density was significantly higher (P<0.05) in the forest trails (1.15 g/$cm^3$) than in the forest area (1.00 g/$cm^3$). The rates of pore space were lower in the forest trails (56.6%) than in the forest area (62.4%). Soil moisture content was significantly different (P>0.05) between the forest trails (13.3%) and the forest area (11.3%) Soil strength was higher at 5 cm of soil depth than at 10 cm of soil depth. It indicates that soil compaction by visitors could be affected at 5 cm of soil depth. Soil strength over 30 cm of soil depth was not significantly different between the forest trails and the forest areas. The content of organic matter, total nitrogen, available phosphorus, and exchangeable cations were lower in the forest trails compared with the optimum content of forest soils because of soil erosion with increasing visitors. These results indicate that it needs a counterplan to protect forest trails from overcrowded visitors.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.817-820
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• 2008

The river environments of many streams in korea have been deteriorate through the rapid industrialization and urbanization since the 1960s. In korea, on the other hand, much efforts on the research and project have been made for the restoration of the deteriorated streams to close-to-nature. in order to restore the deteriorated streams, therefore, it is necessary to investigate such advanced technologies and materials. In view of this requirement, various research paths are being taken focusing on coarse aggregates to make multi-functional porous concrete having continuous voids so as to improve water and air permeability, acoustic absorption, water purification and applicability to vegetation. The Purpose of this study is to investigate the method for recovery of the environment in the streams area using porous concrete retaining wall block. the multi-P.O.C block applies for test in the Jangduri-cheon have been monitored planting, stability etc. after 6 months, plant grows flourishing and reconstructed in state such as nature rivers.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.901-904
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• 2008

Immense quantities of coal combustion by-products are produced every year, and only a small fraction of them are currently utilized. Therefore, this study investigated and analyzed the applications of porous concrete for the efficient utilization of bottom ash. This study examines on application of polymer to improve strength properties of porous concrete using coal-ash. As the results, when the mixing ratio of bottom ash increases, void ratio and coefficient of permeability of porous concrete increases, but its strength decreases. Also, as the mixing ratio of polymer increases, its void ratio and coefficient of permeability decreases. When specific amount of polymer is mixed, we can find its strength properties are improved.

• Korean Journal of Plant Resources
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• 제34권4호
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• pp.249-256
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• 2021

Napa cabbage (Brassica campestris var. Pekinensis) is the main material of Kimchi so that important crop in South Korea. There are two typical napa cabbage cropping systems in the alpine area. One is cultivating napa cabbage annually while another is cultivating napa cabbage and potato biennially. In this research, we evaluated soil physiochemical properties, yield, and mineral contents of napa cabbage depending on two cropping systems. As a result, organic matter, available P₂O₅, exchangeable K⁺ was decreased after six-years of cultivation on both cropping systems. However, soil pH was only decreased in a continuous napa cabbage cropping system. Soil porosity is also decreased in both cropping systems on topsoil while is increased in rotation with potato on subsoil. The rotation system showed a significantly higher yield with a higher value of leaf and napa cabbage size than the continuous cropping system. Total nitrogen, Ca²⁺, and Ma²⁺ were increased and total carbon and phosphate decreased in both cropping systems after six-years. Especially, total nitrogen and Mg²⁺ were significantly higher in the continuous system while Ca²⁺ was higher in the rotation system. In conclusion, the cropping system influences soil physiochemical properties and plant production in an agricultural field.

• Korean Journal of Environment and Ecology
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• 제29권6호
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• pp.923-928
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• 2015

This study was carried out to evaluate the physicochemical properties of different types of topsoil in forest ecosystems by damage pattern and analyse the possibility of using the topsoil as a planting ground construction material. There were 72 samples from 36 sites of 12 damaged areas and 36 sites of 12 non-damaged areas. The results showed that the physicochemical properties of topsoil from non-damaged areas of forest ecosystems were on an average clay loam~sandy loam in soil texture, showing $0.95{\sim}1.10Mg/m^3$ in soil bulk density, $35.7{\sim}44.0m^3/m^3$ in solid phase, 56.0~64.3 in soil porosity, 8.4~35.8% in aggregate stability, 5~13 mm in soil hardness, 5.3~6.1 in pH, 0.14~0.65 dS/m in EC, 0.28~0.42% in T-N, $14{\sim}22cmol^+/kg$ in CEC, $0.15{\sim}0.31cmol^+/kg$ in Ex. $K^+$, $2.07{\sim}2.84cmol^+/kg$ in Ex. $Ca^{2+}$, $0.45{\sim}1.97cmol^+/kg$ in Ex. $Mg^{2+}$, 17~96 mg/kg in Av. $P_2O_5$ and 3.2~5.6% in OM. On the other hand, damaged areas were on an average clay loam~loamy sand in soil texture, showing $1.54{\sim}1.75Mg/m^3$ in soil bulk density, $52.8{\sim}58.0m^3/m^3$ in solid phase, 42.0~47.2 in soil porosity, 4.2~22.5% in aggregate stability, 13~25 mm in soil hardness, 4.8~5.5 in pH, 0.13~0.62 dS/m in EC, 0.02~0.12% in T-N, $5{\sim}15cmol^+/kg$ in CEC, $0.11{\sim}0.18cmol^+/kg$ in Ex. $K^+$, $0.45{\sim}2.36cmol^+/kg$ in Ex. $Ca^{2+}$, $0.39{\sim}0.96cmol^+/kg$ in Ex. $Mg^{2+}$, 15~257 mg/kg in Av. $P_2O_5$ and 0.4~2.2% in OM. After conducting a comparison of physicochemical characteristics of non-damaged forest area and damaged areas, it was found that the physicochemical characteristics of damaged areas were more deteriorated compared to that of non-damaged areas. Therefore, it is judged that it is necessary to establish countermeasures for the conservation and management of the damaged areas for topsoil recycling in the future.

• Journal of the Korea Organic Resources Recycling Association
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• 제24권4호
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• pp.69-76
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• 2016

To produce the primary data for best management of soil nutrient in organically practiced soils, 75 leading organic farms whose paddy fields were certified as organic were selected. Soil samples were collected from the paddy fields before plowing, and then analyzed for the determination of physico-chemical properties. Soil pH, organic matter and available phosphate were analyzed and averaged 6.2, $25.6mg\;kg^{-1}$ and $88.4mg\;kg^{-1}$, respectively. Contrary to the national-scale-surveyed paddy soils including organic and conventional farming, pH was higher, available phosphate was lower in the organically practiced soils, but organic matter was similar. With the increasing cultivation period in organic, soil pH and porosity were also increased, EC, available phosphate, bulk density and soil hardness were lower than those from the national survey. Organic matter, however, was not significantly changed. The bulk density was negatively correlated with the organic matter content for both surface topsoil ($R^2=-0.5424$) and subsoil ($R^2=-0.6429$) (p<0.05). Soil quality is improved in most of soil chemical and physical composition factors excluding organic matter and available phosphate. However, it is necessary to establish the counter measure plan for organic matter management and to develop phosphate-containing materials which can be used as organic agricultural material in the future.

• Tunnel and Underground Space
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• 제21권1호
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• pp.33-40
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• 2011

This study focuses on having a temperature and water pressure effects on the change of material properties of rocks. Granite and limestone specimens from Gagok Mine were thermally treated with predetermined temperatures of 200, 300, 400, 500, 600 and $700^{\circ}C$ (excepting $700^{\circ}C$ for limestone) to estimate the reduction of material properties of rocks caused by heat. Specific gravity, effective porosity, elastic wave velocity, uniaxial compressive strength, Young's modulus and Poisson's ratio for pre-heated specimens were measured. With increasing temperature, material properties of both rock specimens change sequentially. Significant changes of specific gravity, effective porosity and elastic wave porosity occur above $400^{\circ}C$ for granite and $300^{\circ}C$ for limestone. Changes of uniaxial compressive strength, Young's modulus and Poisson's ratio seem to be similar to those of physical properties. GSI of 500, 600 and $700^{\circ}C$ specimens inferred by using uniaxial compressive strength and Young's modulus of preheated granite specimens is found to be 81, 66 and 58 each. In case of pre-heated limestone specimens of 400, 500 and $600^{\circ}C$, the corresponding GSI is 76, 71 and 65 each. 500, 600 and $700^{\circ}C$ granite specimens and 400, 500 and $600^{\circ}C$ limestone specimens were pressurized to 7.5 MPa and their effective porosity, elastic wave velocity, uniaxial compressive strength and Young's modulus were measured. The average value of material properties (mentioned above) of 500, 600 and $700^{\circ}C$ granite specimens under water pressure compared with material properties of non-pressurized pre-heated specimens exhibits the reduction of 7.6, 11.3 and 14.9%, respectively. In case of 400, 500 and $600^{\circ}C$ limestone specimens under water pressure, the average value of material properties decreases by 8.2, 13.8 and 21.9%, respectively.

• Proceedings of the Plant Resources Society of Korea Conference
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• 한국자원식물학회 2019년도 추계학술대회
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• pp.51-51
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• 2019

참취(Aster scaber)는 국화과에 속하는 여러해살이식물로 취나물로 분류되어 전국에서 재배되고 있으며 주로 남부지역에서 조기재배 작형으로 많이 재배하고 있다. 참취의 잎과 줄기는 맛과 향기가 독특하여 예로부터 생채, 묵나물 등으로 이용되어 왔으며 칼슘, 철분, 비타민 A 등이 풍부하여 건강식품으로서도 가치가 높고 한약재로도 사용되기도 한다. 최근에는 항암효과와 더불어 콜레스트롤을 저하시키는 약리적 효능이 있는 것으로 밝혀져 기능성 식품으로도 각광 받고 있다. 참취 시설재배 시 통상 3년 마다 갱신이 이루어지고 있는데 그 이유로는 시설재배지 특성상 양분의 과다투입에 의한 염류집적과 잦은 관수로 물리성이 악화되어 참취의 생육이 저하되어 수량이 감소하는 결과를 초래한다. 본 연구는 토양개량제 처리에 따른 참취의 생육과 토양 물리화학성에 미치는 영향을 검토하여 참취 시설재배 농가에 활용할 수 있는 방안을 개발하고자 시험을 수행하였다. 2018년 4월부터 2019년 9월까지 전라북도 농업기술원 허브산채시험장에서 참취 시설재배를 대상으로 하고 무처리, 볏짚 1,000 kg/10 a, 왕겨 숯 1,000 kg/10 a, 야자섬유 1,000 kg/10 a, 4처리구로 하여 시기별 생육 및 토양특성을 조사하였다. 수확기 참취 생육특성은 초장은 25.6~27.2 cm, 엽장은 8.5~9.7 cm, 엽폭은 6.3~7.0 cm, 경직경은 4.3~4.6 cm, 및 수량은 $3.3{\sim}4.0kg/3.3m^2$으로 볏짚 처리구에서 대조구에 비해 좋은 생육 상황을 보였으며 수량성 또한 많았다. 시험 후 토양화학적 특성을 조사한 결과 토양 pH는 7.4~7.5, 토양유기물 함량은 34~36 g/kg, 유효인산 함량은 386~415 mg/kg 이었으며 처리 전 토양에 비하여 유기물 함량은 증가하고 유효인산은 낮아지는 경향을 보였다. 치환성 양이온 K, Ca, Mg는 K는 $0.8{\sim}1.0cmol_c/kg$로 낮아졌고, Ca와 $8.9{\sim}10.1cmol_c/kg$, Mg는 $3.1{\sim}3.4cmol_c/kg$로 증가하였다. 토양물리성의 변화는 왕겨숯 시용에서 대조구에 비해 가장 낮은 용적밀도 $1.22g/cm^3$와 가장 높은 공극률 54.09%을 보였다. 토양 삼상은 고상은 볏짚에서 51.98%로, 액상은 야자섬유에서 28.64%로, 기상은 왕겨숯에서 29.35%로 가장 높았다. 참취 시설재배지 토양개량제 시용함으로써 토양의 유기물함량 증가와 토양의 용적밀도 감소와 토양양 공극율 증가 등 토양의 물리 화학성을 개선할 수 있을 것으로 기대된다. 본 연구는 2년차 시험 결과로서 3년차에 재검토할 계획이다.