• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.70-70
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• 2020

참취(Aster scaber)는 국화과에 속하는 여러해살이식물로 취나물로 분류되어 전국에서 재배되고 있으며 주로 시설재배지 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 토양 물리화학성과 참취의 생육에 미치는 영향을 검토하여 참취 시설재배 농가에 활용할 수 있는 방안을 개발하고자 시험을 수행하였다. 2018년 4월부터 2020년 7월까지 전라북도 농업기술원 허브산채시험장에서 참취 시설재배를 대상으로 무처리, 볏짚 1,000kg/10a, 왕겨숯 1,000kg/10a, 야자섬유 1,000kg/10a, 4처리구로 하여 시기별 토양특성 변화 및 생육 상황을 조사하였다. 자재 처리 후 3년차 토양 물리성의 변화는 볏짚 시용에서 가장 낮은 용적밀도 1.23g/cm³와 가장 높은 공극률 53.50%을 보였다. 토양 삼상은 고상은 왕겨숯에서 49.41%로, 액상은 왕겨숯에서 24.92%로, 기상은 볏짚에서 32.09%로 가장 높았다. 토양화학적 특성을 조사한 결과 토양 pH는 7.2~7.3, 토양유기물 함량은 32~39g/kg, 유효인산 함량은 440~487mg/kg 이었으며 처리 전 토양에 비하여 유기물 함량은 증가하고 유효인산은 낮아지는 경향을 보였다. 치환성 양이온 K, Ca, Mg는 K는 0.77~0.88cmolc/kg로 낮아졌고, Ca와 11.56~14.09cmolc/kg, Mg는 2.93~3.22cmolc/kg로 증가하였다. 참취 생육특성은 초장은 24.8~26.4cm, 엽장은 8.3~8.7cm, 엽폭은 6.3~6.7cm, 줄기수는 6.9~7.2주로 대조구에 비해 좋은 생육 상황 상황을 보였으며, 수량은 919~1,161kg/10a 으로 자채 처리구에서 대조구에 비해 수량성 또한 높았다 참취 다년재배지 토양개량제 시용함으로써 토양의 유기물함량 증가와 토양의 용적밀도 감소와 토양 공극율 증가 등 토양의 물리화학성을 개선할 수 있을 것으로 기대된다.

• Journal of Soil and Groundwater Environment
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• v.13 no.4
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• pp.1-7
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• 2008

This study analyzed for hydrodynamic dispersion characteristics of multi-soil layer (Silt and clay, Find sand, Coarse sand), data of a field tracer test on the multi-soil layer and data of laboratory column experiments on the samples on each soil layers. Through the analysis of permeability and flow, MS (Silt and clay) and FS (Fine sand), which were low effective porosity, were higher average linear velocity while CS (Coarse sand), which was high effective porosity, was higher hydraulic conductivity. Hydraulic conductivity function based on average soil particle diameter was assumed Y=$3.49{\times}10^{-8}e^{15320x}$ and coefficient of determination was 0.90. Average linear velocity function based on average soil particle diameter was assumed Y=$1.88{\times}10^{-7}e^{11459x}$ and coefficient of determination was 0.81. Longitudinal dispersivity function based on average soil particle diameter was Y = 0.00256$e^{5971x}$ and coefficient of determination was 0.98. According to the linear regression analysis of average linear velocity and longitudinal dispersivity, assumed function was Y = 21.7527x + 0.0063, and coefficient of determination was 0.9979. The ratio of field scale/laboratory scale was 54.09, it exhibited scale-dependent effect of hydrodynamic dispersion. Field longitudinal dispersivity (1.39m) was 7.47 times as higher than longitudinal dispersivity estimated by the methods of Xu and Eckstein (1995). Hydrodynamic dispersion on CS layer was occurred mainly by diffusion flow in the test aquifer.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.69-69
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• 2011

태양열 발전 플랜트에 사용되는 중고온 범위의 축열조에 고체-액체간 상변화를 수행하는 용융염을 축열물질로 사용하면 액체상 또는 고체상만으로 된 열저장 매체에 비해 축열조의 규모를 축소함과 동시에 축열온도의 균일성 향상에 기여할 수 있다. 중온인 $250{\sim}400^{\circ}C$ 범위에서 이용 가능한 용융염으로는 질산칼륨($KNO_3$), 질산리튬($LiNO_3$)등이 있다. 그러나 이러한 용융염의 가장 큰 단점은 열전도율이 매우 낮다는 것이며, 이로 인해 요구되는 열전달률을 성취하기 위해서는 많은 열접촉면적이 필요하다는 것이다. 이러한 단점을 극복하는 방법을 도입하지 않고서는 축열시스템의 소규화를 성취하는데 큰 효과를 가져올 수 없다. 한편 열수송 성능이 탁월한 히트파이프를 사용하면 열원 및 열침과 축열물질 사이의 열전달 효율을 증가시켜 시스템의 성능 향상과 동시에 소규모화에 기여할 수 있다. 중온 범위 히트파이프의 작동유체로서 다우섬-A(Dowtherm-A)는 $150^{\circ}C$이상 $400^{\circ}C$까지의 범위에서 소수에 불과한 선택적 대안 중 하나이다. 따라서 본 연구에서는 용융염을 사용하는 중온 태양열축열조에 적용 가능한 다우섬-A 히트파이프의 성능을 파악하여 기술적 자료를 제시하고자 하였다. 열원으로는 고온 고압의 과열증기, 그리고 열침으로는 중온의 포화증기를 고려하였다. 용융염 축열조를 수직으로 관통하는 히트파이프는 하단부에서 열원 증기와 열교환 가능하며, 중앙부에서 축열물질과 열교환하고, 상단부에서는 중온 증기와 접촉할 수 있도록 배치하였다. 축열모드에서는 히트파이프의 하단부가 증발부로 작동하고, 중앙부가 응축부로 작동하여 용융염으로 열을 방출하면 용융염의 온도가 상승하고 용융점에 도달하면 액상으로의 상변화가 진행되면서 축열이 활성화된다. 축열모드에서 히트파이프의 상단부는 단열부로 작동한다. 방열과정에서는 히트파이프의 하단부가 단열된 상태이고, 중앙부는 용융염으로부터 열을 받아 증발부로 작동하며, 상단부는 중온 증기로 열을 방출하므로 응축부로 작동한다. 즉, 축열시스템의 작동모드에 따라 하나의 히트파이프에서 증발부, 응축부, 단열부의 위치가 변하게 된다. 특히, 히트파이프의 중앙 부분이 응축부에서 증발부로 전환될 때에도 작동이 보장되려면 내부 작동유체의 연속적인 재순환이 가능해야 하므로, 일반 히트파이프에서와는 달리 초기 작동액체의 충전량을 증발부 전체의 체적보다 더 많이 과충전해야 한다. 이러한 히트파이프의 성능 파악을 위한 실험에서 고려한 변수들은 열부하, 작동액체의 충전률, 작동온도 등이며, 열수송 성능의 지표로서는 유효열전도율과 열저항을 이용하였다. 중온범위에서 적정한 작동온도를 성취하기 위해 실험에서는 전압 조절기로 열부하를 조절하는 동시에 항온조로 응축부의 냉각수 입구 온도를 제어하였다. 하나의 히트파이프에 대해서 최대 1 kW까지의 열부하에서 냉각수 입구 온도를 $40^{\circ}C$에서 $80^{\circ}C$ 범위로 변화시키면 히트파이프 작동온도를 약 $250^{\circ}C$ 내외로 조절 가능하였다. 히트파이프 작동액체 충전률은 윅구조물의 공극 체적을 기준으로 372%에서 420%까지 변화 시켰다. 실험 결과를 토대로 열저항과 유효 열전도율을 각각 입력 열유속, 작동온도, 작동액체 충전률 등의 함수로 제시했다. 동일한 냉각수 온도에서는 충전률이 높을수록 히트파이프의 작동온도가 감소하였다. 열저항 값의 범위는 최소 $0.12^{\circ}C/W$에서 최대 $0.15^{\circ}C/W$까지로 나타났으며 유효 열전도율의 값은 최소 $7,703W/m{\cdot}K$에서 최대 $8,890W/m{\cdot}K$까지 변화했다. 최소 열저항은 충전률 420%인 경우에 나타났는데 이때의 작동온도는 약 $262^{\circ}C$이었다. 히트파이프의 작동한계로서 드라이아웃(dry-out)은 충전률 372%의 경우에 열부하 950 W에서 발생하였으나, 그 이상의 충전률에서는 열부하 1060 W까지 작동한계 발생이 관찰되지 않았다. 실험 결과 본 연구에서의 히트파이프는 중온 태양열 축열조에 적용되어 개당 약 1 kW의 열부하를 이송하면서 축열물질 및 축방열 대상 유동매체와 열교환을 하는데 사용하는데 충분할 것이라 판단된다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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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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• v.34 no.4
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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.

• Journal of the Korean Institute of Gas
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• v.27 no.2
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• pp.39-48
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• 2023

This study presents the experimental results to measure the adsorption amount of methane gas by coal according to the conditions of a coalbed methane (CBM) reservoir. Adsorbed gas to coal seam particles was measured under reservoir conditions (normal pressure ~ 1,200 psi pressure range, temperature range15 ~ 45℃) using coal samples obtained from random mines in Kalimantan Island, North Indonesia. The obtained amount of absolute adsorbed gas was applied to triangular with linear interpolation to calculate the maximum amount of adsorbed gas according to temperature and pressure change, at which no experiment was performed. As a result, it was revealed that the amount of adsorbed gas to coal particles increased as the pressure increased and temperature decreased, but the increase of the amount of adsorbed gas decreased at more than an appropriate depth(1,000 ft). In the cleat permeability and cleat porosity for each depth of the coal bed considering the effective stress, the cleat permeability was 28.86 ~ 46.81 md, and the cleat porosity was 0.83 ~ 0.98%. This means that the gas productivity varies significantly with the depth because the reduction of the permeability according to the depth in the coal seam is significant. Therefore, a coalbed depth should be considered essential when designing the spacing of production wells in a coalbed methane reservoir in further study.

• Korean Journal of Environment and Ecology
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• v.29 no.6
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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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• v.24 no.4
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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.

• Economic and Environmental Geology
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• v.49 no.6
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• pp.469-477
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• 2016

To evaluate the $CO_2$ storage capacity for the reservoir rock, the laboratory scale technique to measure the amount of $scCO_2$, replacing pore water of the reservior rock after the $CO_2$ injection was developed in this study. Laboratory experiments were performed to measure the $scCO_2$ displacement efficiency of the conglomerate and the sandstone in Janggi basin, which are classified as available $CO_2$ storage rocks in Korea. The high pressurized stainless steel cell containing two different walls was designed and undisturbed rock cores acquired from the deep drilling site around Janggi basin were used for the experiments. From the lab experiments, the average $scCO_2$ displacement efficiency of the conglomerate and the sandstone in Janggi basin was measured at 31.2% and 14.4%, respectively, which can be used to evaluate the feasibility of the Janggi basin as a $scCO_2$ storage site in Korea. Assuming that the effective radius of the $CO_2$ storage formations is 250 m and the average thickness of the conglomerate and the sandstone formation under 800 m in depth is 50 m each (from data of the drilling profile and the geophysical survey), the $scCO_2$ storage capacity of the reservoir rocks around the probable $scCO_2$ injection site in Janggi basin was calculated at 264,592 metric ton, demonstrating that the conglomerate and the sandstone formations in Janggi basin have a great potential for use as a pilot scale test site for the $CO_2$ storage in Korea.

• Horticultural Science & Technology
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• v.32 no.4
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• pp.499-506
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• 2014

This research was conducted to develop root media containing ground and aged pine bark (GAPB) and ground and raw pine bark (GRPB). After analysis of physico chemical properties, the pine barks were blended with peat moss (PM) or coir dust (CD) in various ratios to formulate 12 root media. Then, two out of 12 root media were chosen based on the physical properties for further experiments. The pre-planting nutrient charge fertilizers (PNCF) were incorporated into two root media and chemical properties were analysed again. The total porosity (TP), container capacity (CC), and air-filled porosity (AFP) of GAPB were 78.7%. 39.4%, and 38.3%, respectively, while those of GRPB were 74.7%, 41.2%, and 33.4%, respectively. The percentage of easily available water (EAW, from CC to 4.90 kPa tension) and buffering water (BW, 4.91-9.81 kPa tension) in GAPB were 12.7% and 8.5%, respectively, which were a little lower than the 13.5% and 8.8% in GRPB. The pH and EC were not different significantly, but cation exchange capacity was different between the two pine barks (GAPB: pH 5.26, EC $0.61dS{\cdot}m^{-1}$, CEC $15.7meq{\cdot}100g^{-1}$; GRPB: pH 5.19, EC $0.32dS{\cdot}m^{-1}$, CEC $9.32meq{\cdot}100g^{-1}$). The concentrations of exchangeable cations in GAPB were Ca 0.32, K 0.05, Mg 0.27 and $0.12cmol+{\cdot}kg^{-1}$, whereas those in GRPB were Ca 0.28, K 0.08, Mg 0.25 and $0.09cmol+{\cdot}kg^{-1}$. The concentrations of $PO_4$-P, $NH_4$-N and $NO_3$-N were 485.8, 0.62 and $0.91mg{\cdot}L^{-1}$ in GAPB and 578, 1.00 and $0.82mg{\cdot}L^{-1}$ in GRPB, respectively, when those were analyzed in the solution of the saturated paste. The TP, CC and AFP in the two selected media were 89.3 and 76.3, and 13.0% in PM+GAPB (8:2, v/v) and 88.2, 68.2 and 20.0% in CD+GRPB (8:2), respectively. The pHs and ECs were 3.8 and $0.24dS{\cdot}m^{-1}$ in PM+GAPB which were a little lower than 5.8 and $0.65dS{\cdot}m^{-1}$ in CD+GRPB. However, the pHs analysed before and after incorporation of PNCF in the two root media did not show large differences. This is because the solubility of dolomitic lime is very low, and the pH it is expected to rise gradually when crops are cultivated int he root media. The information obtained in this study should facilitate effective formulation of root media containing pine bark.