• 한국토양비료학회지
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• 제48권5호
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• pp.326-331
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• 2015

High salinity and sodicity of soils play a negative role in producing crops in reclaimed tidal lands. To evaluate the effects of soil ameliorants on salt removal in a highly saline and sodic soil of reclaimed tidal land, we conducted a column experiment with treating gypsum, compost, and phosphate at 0-2 cm depth and measured the salt concentration of leachate and soil. Electrical conductivity of leachate was $45-48dSm^{-1}$ at 1 pore volume (PV) of water and decreased to less than $3dSm^{-1}$ at 3 PV of water. Gypsum significantly decreased SAR (sodium adsorption ratio) of leachate below 3 at 3 PV of water and soil ESP (exchangeable sodium percentage) below 3% for the whole profile of soil column. Compost significantly decreased ESP of soil at 0-5 cm depth to 5% compared with the control (20%). However, compost affected little the composition of cations below a depth of 5 cm and in leachate compared with control treatment. It was concluded that gypsum was effective in ameliorating reclaimed tidal lands at and below a soil layer receiving gypsum while compost worked only at a soil layer where compost was treated.

• 한국토양비료학회지
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• 제50권6호
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• pp.634-643
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• 2017

No-tillage is an effective practice to save labor input and reduce methane emission from the paddy. Effects of tillage and cultivation methods on carbon accumulation and soil properties were investigated in the treatments of tillage-transplanting (T-T), tillage-wet hill seeding (T-WS), minimum tillage-dry seeding (MT-S) and no-tillage dry seeding (NT-S) of rice. Soil carbon was higher in NT-S and MT-S, compared to T-T and T-WS. In NT-S and MT-S, soil carbon contents were the highest in the top soil (5 cm depth) and decreased with soil depth. In T-T and T-WS, however soil carbon contents showed no significant difference up to soil depth of 15 cm from the top. Carbon content was the highest in the soil particle size under $106{\mu}m$ and decreased as the soil particle size increased. Contents of water-stable aggregates in NT-S and MT-S were higher than those of T-T and T-WS. In NT-S and MT-S, contents of water-stable aggregates were the highest in the top soil and significantly decreased with soil depth while no significant difference up to the soil depth of 15 cm in T-T and T-WS. Available $SiO_2$ contents in the top soil were the highest in NT-S and MT-S while the lowest in T-T and T-WS. It is concluded that minimum or no disturbance of soil in rice cultivation can increase carbon accumulation in the soil, especially in the top layer, and subsequently contribute to the formation of the water-stable soil aggregates.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.120-129
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• 2000

As structure-soil interaction analysis for the seismic analysis of structures requires a nonlinear analysis of a structure-soil system considering the inelastic characteristics of soil layers nonlinear analyses of the foundation-soil system with the horizontal excitation were performed considering the nonlinear soil conditions for the nonlinear seismic analysis of structures. Stiff soil profile of SD and soft soil profile of SE specified in UBC were considered for the soil layers of a foundation and Ramberg-Osgood model was assumed for the nonlinear characteristics of soil layers. Studies on the changes of dynamci stiffnesses and damping rations of surface and embedded foundations depending on foundation size soil layer depth and piles were performed to investigate the effects of the nonlinear soil layer on the horizontal and rotational dynamic stiffnesses and damping ratios of the foundation-soil system According to the study results nonlinear prperties of a soil laryer decreeased horizontal and rotational linear stiffnesses and increased damping ratios largely Effects of foundation size soil layer depth and piles were also significant suggesting the necessity of nonlinear seismic analyses of structures.

• 한국약용작물학회지
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• 제19권4호
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• pp.246-250
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• 2011

This study was carried out to investigate the characteristics of Rhizome rot incidence of Platycodon grandiflorus by cultivation period and ridge width and furrow depth. The three types of ridge width 0.8, 1.0, and 1.2 m and several levels of furrow depth and 6 levels cultivation period. This experiment was done in farmer's farm and the treatments were also classified in the same spot. In this investigation, ridge width, soil water content, soil hardness, and cultivation period were positively related with Rhizome rot incidence, however, furrow depth was negatively related with that. So this experiment could draw a conclusion : excess water damage and soil hardness could directly or indirectly effect on the Rhizome rot incidence, so cultivation method should be developed such as making underground ditch or cultivation in well draining soil for escaping excess waster damage.

• Journal of Biosystems Engineering
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• 제9권2호
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• pp.27-36
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• 1984

This study was carried out to investigate the effects of the tilling depth, tilling travel speed and soil shear stress on the tilling load characteristics and power requirement for rotary tillers. The results obtained from the study are summarized as follows. 1. The average and maximum PTO torque increased as the tilling depth, tilling pitch and soil shear stress increased. A multiple linear regression equation to estimate the average PTO torque in terms of the above parameters was developed. 2. The ratios of maximum PTO torque to the average torque were in the range of 1.17 to 1.65 for the various tilling conditions tested. The variation in PTO torque increased greatly as the tilling pitch and soil shear stress increased, but decreased as the tilling depth increased. 3. Power requirement for the PTO shaft increased with the tilling depth, travel speed and soil shear stress, but decreased slightly as the tilling pitch increased. A multiple linear regression equation to estimate power requirement for the PTO shaft in terms of the above parameters was developed. 4. The specific power requirement for the rotary tiller was in the range of $0.008-0.015ps/cm^2$ for the various tilling conditons tested. The specific tilling capacity decreased as the tilling depth and soil shear stress increased, but increased with the tilling pitch. A multiple linear regression equation to estimate the specific tilling capacity in terms of the above parameters was developed.

• 한국지반공학회지:지반
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• 제9권1호
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• pp.7-20
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• 1993

1988년 건설부에서 제정한 건축물에 대한 재진설계규준'에는 저면 전단력 산정시 지반계수가 1.0, 1.2, 1.5로 구분되어 있는데, 특히 얕은지반의 연약층에서 지반계수의 선정이 모호할 때가 많다. 또한 우리나라의 지반특성은 대부분 퐁화암 및 연암층이 20m이내에서 발견됨을 고려하여, 일차원 파전파 이론과 반무한 탄성이론 및 문헌을 통한 분석을 통해 지진 하중시 지반의 조건이 저면 전단력에 미치는 증폭효과를 비교분석하여 내진 설계시 적절한 지반계수 선택을 할 수 있도록 하였다.

• 환경위생공학
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• 제7권1호
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• pp.87-94
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• 1992

In order to investigate the content of heavy metals in soil according to vertical profiles, 72 soil samples were collected from 4 sampling sites : Ulchiro-2 ga, Dugdo, Sungnaedong, and Amsa- dong. The content of mercury was measured by a mercury analyzer and those of lead, copper and zinc were measured by an atomic absorption spectrophotometer. From the results of this study, it was shown that the content of heavy metals decreased gradually from the surface soil to the 2 m- depth soil. But, there was no difference in the contents of the heavy metals in the 3m, the 4m and the 5m-depth soil.

• Journal of Biosystems Engineering
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• 제34권3호
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• pp.190-196
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• 2009

The temperature of root zone is known as an important factor for the growth of crops and reduction of energy in greenhouse. The purpose of this study was to design the solar energy supply system to keep the optimum condition of root zone by soil warming. As a result of this study, soil warming compared with no warming changed on a large scale temperature rise effect by depth of soil. The greenhouse's inner temperature have an effect on the temperature of surface up to 15 cm, rised to about 1 hour after warming. In case of the temperature fluctuation, soil temperature was about $12^{\circ}C$ up to 15${\sim}$25 cm and it was $13.4^{\circ}C$ at greater depths. This results showed that the position of root zone was very different after 3 weeks of growth.

• Geomechanics and Engineering
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• 제20권4호
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• pp.333-343
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• 2020

Preventing or reducing the damage impact of lateral soil movements on piled foundations is highly dependent on understanding the behavior of passive piles. For this reason, a detailed experimental study is carried out, aimed to examine the influence of soil density, the depth of moving layer and pile spacing on the behavior of a 2×2 free-standing pile group subjected to a uniform profile of lateral soil movement. Results from 8 model tests comprise bending moment, shear force, soil reaction and deformations measured along the pile shaft using strain gauges and others probing tools were performed. It is found that soil density and the depth of moving layer have an opposite impact regarding the ultimate response of piles. A pile group embedded in dense sand requires less soil displacement to reach the ultimate soil reaction compared to those embedded in medium and loose sands. On the other hand, the larger the moving depth, the larger amount of lateral soil movement needs to develop the pile group its ultimate deformations. Furthermore, the group factor and the effect of pile spacing were highly related to the soil-structure interaction resulted from the transferring process of forces between pile rows with the existing of the rigid pile cap.

• Journal of Biosystems Engineering
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• 제23권2호
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• pp.135-146
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• 1998

The equation to predict the soil temprature of Pusan and Chinju city as a function of time and soil depth for the geothermal energy utilization system and agriculture was devised. The equation was $T(x,t)\;=\;Tm\;-\;To{\cdot}ExP(-{\xi}){\cdot}cos{{\omega}{\cdot}[t-to-x/(2{\cdot}{\alpha}{\cdot}{\omega})^{0.5}]}$ with the soil thermal diffusivity, ${\alpha},\;of\;0.4\;\textrm{m}^2/day,\;0.0375\;\textrm{m}^2/day$ and phase zero point, to, of 24 days, 22.4 days in Pusan and Chinju city, respectively, during ten years from 1987 to 1996. The predicted and measured soil temperatures agreed well with the coefficient of determination of 0.95 at the soil depth of 0.0, 0.5, 1.0, 3.0, 5.0 m. The maximum and minimum temperature in Pusan 3.7, $30.1^{\circ}C$ at soil surface and 14.3, $18.0^{\circ}C$ at the depth of 5.0 m. The total mean temperature of soil in Pusan and Chinju city was about 16.3, $16.0^{\circ}C$, respectively.