• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.207-210
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• 2004

Effect of electron accepters on anaerobic degradation of petroleum hydrocarbons by an anaerobic sludge taken from a sludge digestion tank in a soil artificially contaminated with 10,000 mg/kg soil of diesel fuel was tested. Treatments of soil with 30 mL of the digestion sludge (2,000 mg/L of vss (volatile suspended solids)) were incubated under several anaerobic conditions including nitrate reducing, sulfate reducing, methanogenic, and mixed electron accepters conditions for 120 days. Treatments with the digested sludge showed significant degradation of diesel fuel under all anaerobic conditions compare to control treatments with an autoclaved sludge and without the sludge. The amount of TPH degradation after 120days incubation was the largest in the treatment with the sludge and mixed electron accepters (75% removal of TPH) followed in order by sulfate reducing, nitrate reducing, methanegenic condition as 67%, 53％, 43%, respectively. However, the rate of TPH degradation in the nitrate- and sulfate reducing condition within 105 days were comparable with that of the mixed electron accepters condition. Microorganisms in each electron acceptor condition were plated on solid mediums containing nitrate or sulfate as sole electron acceptor and several nitrate- and sulfate reducing bacteria showed effective degradation of diesel fuel within 30 days incubations. These results suggest that anaerobic degradation of diesel fuel in soil with digested sludge is effective for practical remediation of soil contaminated with petroleum hydrocarbons.

• 생명과학회지
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• 제9권4호
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• pp.368-374
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• 1999

Three soybean cultivars, Hwangkeum, Tanyeob and Enrei were planted in the same pot under glasshouse conditions to investigate the influence of the different soil water content such as pF 1.4(wet), 2.1(control) and 3.6(dry) on the transpiration rate, dry matter production and water requirement. The transpiration rate remained the high constant rates under the wet soil condition and the control than the dry condition, and showed a linear correlation between transpiration rate and solar radiation under the all condition of soil water. The transpiration rate highly increased in the morning, but dramatically decreased in the other time in a day. The dry matter production was higher under the conditions of wet soil and the control than that under the dry condition. Also, the dry matter production Tanyeob was higher than other cultivars under all soil water content. The water requirement was higher for Enrei and lower Tanyeob than the control.

• Ocean Systems Engineering
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• 제5권1호
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• pp.1-19
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• 2015

The water jetting system for a jack-up spudcan requires the suitable design considering the platform/spudcan particulars, environments, and soil conditions, either the surficial clay or surficial sand. The usage of water jetting depends critically on soil conditions. The water jetting is usually used for the smooth and fast extraction of the spudcan in the surficial clay condition. It is also required for inserting spudcan up to the required depth in the surficial sand condition, which is investigated in this paper. Especially, it should be very careful to use the water jetting during an installation of spudcan in the surficial sand condition, because there is a risk of overturning accident related to the punch-through. Therefore, in this study, the effect of water jetting flow rate and time on the change of soil properties and penetration resistance is analyzed to better understand their interactions and correlations when inserting the spudcan with water jetting in surficial sand condition. For the investigation, a wind turbine installation jack-up rig (WTIJ) is selected as the target platform and the multi layered soil (surficial sand overlaying clays) is considered as the soil condition. The environmental loading and soil-structure interaction (SSI) analysis are performed by using CHARM3D and ANSYS. This kind of investigation and simulation is needed to decide the proper water jetting flow rate and time of spudcan for the given design condition.

• 한국환경복원기술학회지
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• 제1권1호
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• pp.18-27
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• 1998

To investigate the restoration progression on soil physical properties and vegetation at the surface of logging road affected by timber harvesting operation. This study was carried out at logging roads constructed from 1989 to 1994 in Mt. Baekwoon, Kwangyang, Chollanam-do. Judging from the analysis of soil hardness, there were significant changes in the depth of soil between 5 and 10cm. Soil hardness was recovered from the compacted condition to the natural forest condition after 9 years passed. Soil macroporous ratio (pF2.7) of topsoil was higher than that of deep soil. Soil moisture retention of topsoil was more improved than that of deep soil. From the view of soil bulk density, the necessary time for recovering to the undisturbed condition of forest soil was about 10 years in the logging road left. Soil physical properties such as soil bulk density and porous ratio were recovered as time passed. Improved soil physical properties promoted the plant recovery on the logging road surface. The dominant species on the logging roads were Comus kousa, Prunus sargentii as overstory species, Rubus crataegifolius, Lespedeza bicolor as understory species, and Saussurea gracilis, Pteridium aquilinum var. latiusculum as herbaceous species. The plant recovery of bank-slopes was faster than that of cut-slopes and road surface. In progress of year, average plant coverage were 70 to 90% in cut- and bank-slopes and 30 to 60% on the logging road, surface which was elapsed 9 years after logging road construction. Therefore, additional planting and seeding work could be effective to the soil condition and vegetation restoration.

• 한국환경복원기술학회지
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• 제9권3호
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• pp.76-81
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• 2006

The reinforcement of soil shear strength by nylon net as substitute materials simulating a fine root system was evaluated by soil strength parameters(apparent cohesion(c) and internal friction angle(tan${\phi}$), using simple shear tester which clearly depicts shear deformation and controls soil suction. And the results of shear test by using bamboo as a substitute materials simulating a main root system and using nylon net as a substitute materials simulating a fine root system were compared. The reinforcement of soil strength by nylon net are expressed by apparent cohesion more than internal friction angle. In addition the increment of apparent cohesion by nylon net reached a peak in suction 60 $cmH_2O$. Different from with bamboo, the possibility of the change on internal friction angle(tan${\phi}$) caused by the soil water condition was shown in shear strain 20% condition. These results show that the mechanism of reinforcement by substitute materials simulating root system may be different in the condition of various soil water content.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권6호
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• pp.27-33
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• 2011

Infiltration plays an important role in the urban water cycle. Infiltration has a potential to contribute to groundwater recharge in addition to runoff reduction. However, infiltration in urban areas has been considered only as a means of runoff reduction. Conventional design methods for infiltration facilities assume soils to be fully-saturated for the sake of simplicity. The amount of groundwater recharge can not be estimated properly with this scheme. Hence, the characteristics of the unsaturated soil condition need to be considered. The finite element model using SEEP/W to estimate infiltration under the unsaturated condition is presented. Infiltration tests for Joomonjin sand are performed and the infiltration behavior of Joomoonjin sand under the unsaturated condition is measured experimentally to verify the validity of the finite element model. The results from comparing infiltrated volume between the saturated and the unsaturated conditions under the same soil and rainfall conditions show that the infiltrated volume in the unsaturated condition is two times bigger than that in the saturated condition.

• 한국토양비료학회지
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• 제19권2호
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• pp.153-156
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• 1986

수온 및 지온변화에 단독(單獨) 또는 혼합(混合) 서식(棲息)하는 좀개구리밥, 붕어마름 및 조류등(藻類等)이 미치는 영향(影響)을 구명(究明)코자 1/200a 대형무저토관(大型無底土管)에서 조사연구(調査硏究)한 결과(結果)는 다음과 같았다. 1. 담수토양(湛水土壤)의 일중(日中) 최고수온 및 지온은 좀개구리밥 서식지(棲息地)가 무서식지(無棲息地)보다 $1{\sim}3^{\circ}C$정도(程度) 낮았으나 최저수온 및 지온은 같거나 $0.5^{\circ}C$정도(程度) 높았다. 2. 담수토양(湛水土壤)의 천기별(天氣別) 수온 및 지온은 좀개구리밥 서식지(棲息地)가 무서식지(無棲息地)보다 맑은 날은 $0.1{\sim}0.3^{\circ}C$ 낮았으나 구름 강우(降雨) 개임시(時)는 $0.1{\sim}0.4^{\circ}C$정도(程度) 높았다. 3. 조류서식(藻類棲息) 담수토양(湛水土壤)의 수온 및 지온은 무서식지(無棲息地)보다 $0.3{\sim}1.0^{\circ}C$ 높아 조류(藻類)에 의한 보온효과가 認定되었다. 4. 잡초서식(雜草棲息) 형태별(形態別) 수온 및 지온 보존(保存) 효과는 붕어마름 단독서식(單獨棲息)>혼합서식(混合棲息)>분개구리밥 단독서식(單獨棲息)>무서식(無棲息) 순(順)으로 높았다.

• 한국조경학회지
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• 제27권1호
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• pp.122-131
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• 1999

Indoor environments are usually less than optimal for the growth of ferns, especially in regards to the water condition. These studies were performed to investigate responses involved in causing growth of ferns and presume management plan against the water deficit under indoor conditions. The effect of air humidity and soil moisture on the ferns was examined in Adiantume raddianum and Selaginella kraussiana. Results of experiments are as follows; 1. Under a low humidity condition, having a 25-50% RH. ornamental value of ferns decreased much more than under a 90% RH. Under a low soil moisture, such as sand treatment, ornamental value of ferns also decreased. 2. Leaf chlorophyll content, water content and stomata situations increased as air humidity and soil moisture went up. 3. Even if air humidity and soil water were not enough for ferns growth, the extending of irrigation cycle was helpful. 4. Under extremely low air humidity conditions, some water management, namely, using water holding soil or extending of irrigation cycle was desirable. Other methods of increasing air humidity, including water instruments such as ornamental pools, waterfalls, or fountains, grouping plants together were also helpful. But spraying water on leaves increased injury to ferns growth because of excess evaporation from the leaves. Though these studies, we learn that ferns are susceptible to water condition such as air humidity, soil water and water management. If other environmental factos are maintained with optimal conditions, water condition plays an important role in ferns growth in indoor environments.

• 한국조경학회지
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• 제28권4호
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• pp.21-28
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• 2000

This study is conducted to analyze effects of soil moisture on the growth of maple(Acer palmatum) under indoor low light intensity. Maples grew under three different light intensities such as sunny place(average 353.2W/$m^2$), half shade(average 7.7 W/$m^2$) and shade/(average 1.9W/$m^2$).Under half shady and shady condition, each 24 planters(2 maples planted in each planter) were used and divided into 3 groups treated with different watering points. Three levels of soil water potential were set for watering points, such as -200mbar, -300mbar or -500mbar. Under sunny condition, there were only group of 8 planters, as comparison. Watering was applied when soil water potentials reached -500maber. The results of plant growth experiment are as followed. 1. Under the shady condition, 32 maples died among 48 maples for 7 months. 9 maples survived, watered at soil water potential -200mbar, 5maples at -300mbar and 2maples at -500mbar. 2. Leaf water content ratios were higher under lower light intensity. For the cell wall became thinner under lower light intensity. 3. Maples in shady were easy to die due to having thin cell wall, therefore they were easy to loss the turgor pressure. 4. In case of half shady condition, the group, watered at soil water potential -200mbar, had much smaller amount of rootlet than -300mbar, because there were excessive soil water. The group, watered at soil water potential -500mbar, had smaller amount of rootlet than -300mbar and there was a remarkable difference in leaf water potential in spite of nearly same soil water potential, because leaves received the water stress under lower soil water potential. 5. When maples grew soundly, the leaf water potential was largely influenced by the soil water potential.

• 한국토양비료학회지
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• 제29권3호
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• pp.243-248
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• 1996

잠재 산성황산염토양의 산화과정과 이 토양에서 유래된 잠재 산성황산염토양을 칼럼에 넣고 개량제 시용에 따른 토양특성의 변화에 대한 연구결과는 다음과 같다. 1. 잠재 산성황산염토양의 건조와 담수 조건에서 토양 pH변화는 시간의 경과에 따라 두 조건 모두 낮아지는 경향을 나타내었는데 그 낮아지는 폭이 건조조건에서 더 크게 나타났다. 2. Sulfate-sulfur의 함량은 건조조건에서 증가하였으나 담수상태에서는 점점 감소하는 경향이었으며 sulfide-sulfur의 함량은 담수조건이 더 높게 나타났다. 3. 2가 철의 함량은 시간의 지남에 따라 담수조건에서 함량이 더 높았고 건조조건에서는 서서이 감소하는 경향이었으며 치환성 알루미늄의 함량은 건조와 담수 두 조건에서 모두 증가하였다. 4. 컬럼을 이용한 모델실험에서 잠재 산성황산염토양에 농용석회, 암모니아수를 처리하여 중화시킨 후시간이 경과됨에 따라 대조구에 비하여 pH가 상승하였지만 그 효과가 크게 나타나지는 않았다. $Eh_6$는 암모니아수 처리가 제일 낮았으며 다음이 농용석회, 대조구의 순서였다. 5. 칼럼용출액 중의 sulfate-sulfur와 치환성 알루미늄의 함량은 시간이 경과함에 따라 모든 처리구에서 감소하는 경향이었고, sulfide-sulfur와 2가 철의 함량은 증가하는 경향이었다.