• 한국지반공학회논문집
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• 제27권3호
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• pp.5-17
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• 2011

실내시험의 경우 샘플링으로 인한 시료의 교란은 종종 지반의 공학적 특성을 추정하는데 상당한 오차를 발생시키기 때문에 현장지반의 거동을 분석하는데 있어 부적절한 결과를 초래한다. 따라서 본 연구에서는 원위치시험법 중 하나인 스크류재하시험을 개발하였다. 그 이유는 신뢰성 있는 공학적 파라메터를 산정하기 위해서는 원위치시험법을 채택하는 것이 유리하기 때문이다. 스크류재하시험은 나선형의 오거 재하판을 지반 속에 관입하여 재하시험을 하는 평판 재하시험의 개량된 시험이다. 본 연구를 통해 스크류시험장치에 대한 구조와 특성을 자세히 소개하고 실내시험 결과를 통해 장치에 대한 신뢰성을 검증하였다.

• 한국환경생태학회지
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• 제3권1호
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• pp.81-94
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• 1989

가야산국립공원 등산로 및 야영장의 훼손과 주변 자연환경에 대한 이용영향을 파악하기 위해 1989년에 조사를 실시하였다. 등산로폭, 나지노출폭 및 최대 깊이는 이용강도에 따른 차이가 인정되었고, 전체 51개 조사지 점에서 관찰된 훼손형태는 매우 다양하였으며, 훼손된 지점의 등간로 상태중 최대깊이와 등산로물매는 건전한 지점의 상태와 유의한 차이를 보였다. 등산로주변 토양 및 식생인자의 변화경향을 이용영향의 형태에 따라 구분하여 파악할 수 있었고 등산로주변부에 미치는 이용영향은 약 15m에 이르는 것으로 생각된다. 야영장의 훼손은 심각하여 피해도 5등급의 비율이 약 36%이었고 3등급이상인 지역도 약 69%에 달하였다. 야영장에서의 이용활동이 수목의 직경생장을 크게 저해하는 것으로 나타났으며. 종구성의 이질화를 극심하게 진행시키고 있었다. 야영장의 이용강도의 차이나 이용영향의 범위를 파악하는데 적합한 토양 및 식생인자들을 확인할 수 있었으며, 이용간섭의 영향범위는 약 50m이었다. 야영행위에 대한 내성수종은 물푸레나무, 개옻나무, 노린재나무, 국수나무 등이었다.

• The Korean Journal of Ecology
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• 제23권5호
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• pp.369-375
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• 2000

도시에서 토양을 보존하고 합리적으로 이용하기 위하여 도시 토양을 과학적으로 이해하는 것이 필요하지만 아직까지 이처럼 과도하게 관리되고 교란된 토양의 특성에 대하여 집중적으로 연구되지 않았다. 본 연구에서 조사된 인천의 산림, 잔디밭, 가로수, 나지 및 포장 밑 토양에서 답압에 의한 견밀화에 의하여 토양 가밀도가 높았다. 또한 다양한 도시 토양에서 수분함량은 전원지 산림 토양에 비하여 적었고 지온은 높았다. 화학적으로는 도시 토양에서 pH가 중성에 가깝고 유기물 함량이 적었다. 도시 토양의 총세균수는 전원지 산림 토양의 단지 5∼50% 수준이었다. 단계식 다중회귀분석의 결과, 토양 유기물함량이 총세균수에 영향을 미치는 주요한 요인으로서 선정되었다. 대부분의 도시 토양에서 탈수소효소 활성도는 전원지 산림 토양과 유의한 차이가 없었으나, 아스팔트 포장 밑 토양에서는 낮았다 그러므로 견밀한 도시 토양에서 낮은 유기물함량이 물질 순환에 관여하는 미생물 수에 악영향을 미친다고 판단되었다.

• Journal of Applied Biological Chemistry
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• 제43권3호
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• pp.170-175
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• 2000

A pot-lysimeter experiment was conducted with 3-year-old 'Tsugaru' apple (Malus domestica Borkh) trees to examine the changes in oxygen diffusion rate (ODR) with lateral flow velocity of water through soil. The influence of lateral water flow velocity on water relations and elemental content in leaf, and sap temperature distribution patterns of the xylem of trees were also determined. Trees were grown under four soil water regimes: (1) fast laterally flowing (FWT, $2.50{\times}10^{-4}cm\;s^{-1}$), (2) slow laterally flowing (SWT, $0.25{\times}10^{-4}cm\;s^{-1}$), and (3) stagnant water table (WLT) at 60-cm, and (4) drip-irrigation at -40 kPa of soil matric potential as a control. The rate of $O_2$ diffusion converged near $2{\times}10^{-3}g\;m^{-2}\;min^{-1}$ for FWT and control soils, but decreased below $1{\times}10^{-3}g\;m^{-2}\;min^{-1}$ 40 days after treatment (DAT) for WLT soils. For SWT soils, however, the ODR at 15 cm below the soil surface was similar to that of control, but at 45 cm below the soil surface, ODR was similar to that of the WLT treatment. Leaf water potential of FWT and SWT plants was similar to that of control plants, but the values for SWT plants declined by 98 DAT. Leaf water potential of WLT plants decreased from -1.86 MPa (9 DAT) to -2.41 MPa (59 DAT) and finally down to -2.70 MPa. The sap temperature measured at 1100-hr was lowest at top and highest at bottom for FWT and control plants, but this pattern of SWT and WLT plants was disturbed from 29 DAT. However, for SWT plants, such thermal disturbance of sap temperature disappeared from 63 DAT.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.649-656
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• 2000

Consolidation of the ground surrounding the sand piles is delayed by well resistance and smear effect. This study is executed to understand the factors that affect the characteristics of consolidation. This was accomplished by utilizing the estimated and measured values of the soil properties through the monitoring of the ground surrounding the sand piles. When it is assumed that the horizontal coefficient is equal to the vertical coefficient of consolidation, the estimated values is exceedingly similar to the measured values. The properties of the initially disturbed soil by the sand pile installation seemed to improve through the process of consolidation with the passage of time. From the results of the analysis of the settlement measurement, the measured values occurred about 60～90% of the predicted values. Considering the initial radical compression deformation, according to the theory of cavity expansion, the difference between the two appears to be in good agreement. In this study, to understand the behavioral characteristics of the ground surrounding the sand piles requires estimation through considering the initial radial compression as well as smear effect of the soil disturbance and well resistance.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.698-705
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• 2004

Application of structural load on soft ground can cause lateral movement as well as ground break due to pressing and shearing of ground. Especially, abutment supported by pile foundation can make pile deformed due to lateral movement of ground in order to have harmful effect on structure. According to the result of this study, it is required to consider disturbance of weak soil layer when using lateral movement countermeasure method by EPS construction method as a result of performing study on safety review and EPS construction method with respect to this based on site where lateral movement occurs due to backside soil filling load at bridge abutment installed on weak ground, and it is required to sufficiently consider soil reduction during design of EPS construction method due to lateral movement deformation of soft clay layer by losing ground horizontal resistance force due to plasticity of ground around pile as well as combination part damage with pile head and expansion foundation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.571-578
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• 2009

Recently, micropiling techniques are increasingly applied in foundation rehabilitation/underpinning and seismic retrofitting projects where working space provides the limited access for conventional piling methods. Micropiling techniques provide environmental-friendly methods for minimizing disturbance to adjacent structures, ground, and the environment. Its installation is possible in restrictive area and general ground conditions. The cardinal features that the installation procedures cause minimal vibration and noise and require very low ceiling height make the micropiling methods to be commonly used for underpin existing structures. In the design point of view, the current practice obligates the bearing capacity of micropile to be obtained from skin friction of only rock-socketing area, in which it implies the frictional resistance of upper soil layer is ignored in the design process. In this paper, a new micropiling method and its verification studies via field installation are presented. The new method provides a specific way to grout bore-hole to increase frictional resistance between surrounding soil and pile-structure and it allows to consider the skin friction of micropiles for upper soil layer during design process.

• Geomechanics and Engineering
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• 제33권5호
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• pp.453-462
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• 2023

Intermediate Geomaterials (IGMs) are natural formation materials that exhibit the engineering behavior (strength and compressibility) between soils and rocks. The engineering behavior of such material is highly unpredictable as the IGMs are stiffer than soils and weaker/softer than rocks. Further, the characterization of such material needs exposure to both soil and rock mechanics. In most conventional designs of geotechnical structures, the engineering properties of the IGMs are either aligned with soils or rocks, and this assumption may end up either in an over-conservative design or under-conservative design. Hence, many researchers have attempted to evaluate its actual engineering properties through laboratory tests. However, the test results are partially reliable due to the poor core recovery of IGMs and the possible sample disturbance. Subsequently, in-situ tests have been used in recent years to evaluate the engineering properties of IGMs. However, the respective in-situ test finds its limitations while exploring IGMs with different geological formations at deeper depths with the constraints of sampling. Standard Penetration Test (SPT) is the strength-based index test that is often used to explore IGMs. Moreover, it was also observed that the coefficient of variation of the design parameters (which represents the uncertainties in the design parameters) of IGMs is relatively high, and also the studies on the probabilistic characterization of IGMs are limited compared with soils and rocks. With this perspective, the present article reviews the laboratory and in-situ tests used to characterize the IGMs and explores the shear strength variation based on their geological origin.

• 한국농공학회지
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• 제37권3_4호
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• pp.61-71
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• 1995

Natural ground is a composite consisted of the three phases of water, air and soil paircies. Among the three components, water as a material is weU understood but soil particles are not in foundation engineering. Especially, weathered granite soil generally shows a large volumetric expansion when they freeze. And, the stability and durability of the soil have shown decreased with repetitive freezing and thawing processes. These unique charcteristics may cause various construction and management problems if the soil is used as a construction material and foundation layers. This project was initiated to investigate the soil's physical and engineering characteristics resulting from freezing and freezing-thawing processes. Research results may be used as a basic data in solving various problems related to the soil's unique characteristics. The following conclusions were obtained: The degree of decomposition of weathered granite soil in Kangwon-do was very different between the West and East sides of the divide of the Dae-Kwan Ryung. Soil particles distributed wide from very coarse to fine particles. Consistency could be predicted with a function of P200 as LL=0.8 P200+20. Permeability ranged from 10-2 to 10-4cm/sec, moisture content from 15 to 20% and maximum dry density from 1.55 to 1.73 g /cmΥ$^3$ By compaction, soil particles easily crushed, D50 of soil particles decreased and specific surface significantly increased. Shear characteristics varied wide depending on the disturbance of soil. Strain characteristics influenced the soil's dynamic behviour. Elastic failure mode was observed if strain was less than 1O-4/s and plastic failure mode was observed if strain was more than 10-2/s. The elastic wave velocity in the soil rapidly increased if dry density became larger than 1.5 g /cm$^3$ and these values were Vp=250, Vg= 150, respectively. Frost heave ratio was the highest around 0 $^{\circ}C$ and the maximum frost heave pressure was observed when deformation ratio was less than 10% which was the stability state of soil freezing. The state had no relation with frost depth. Over freezing process was observed when drainage or suction freezing process was undergone. Drainage freezing process was observed if freezing velocity was high under confined pressure and suction frost process was occurred if the velocity was low under the same confined process.

• 한국환경생태학회지
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• 제2권1호
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• pp.50-65
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• 1988

치악산국립공원의 구룡사지구를 대상으로 등산로 및 야영장의 훼손실태와 그 주변토양 및 식생환경의 변화를 조사하였다. 등산로의 상태를 표현하는 등산로 폭 및 나지노출폭은 이용밀도에 따른 차이가 인정되었으며. 최대깊이는 등산로물매와 직선회귀관계($R^2$=0.35)가 성립되었다. 전구간에 걸쳐 출현빈도가 높은 등산로 훼손형태는 암석노출 (48%). 종침식(29%), 및 뿌리노출(27%) 등의 순이었으며 등산로물매가 훼손발생에 많은 영향을 미치는 것으로 나타났다. 등산로 주변토양 및 식생인자의 변화경향은 일정하지 않았으나 이용객의 간섭형태에 따라 변화경향을 구분할 수 있었다. 야영장에서의 수목훼손형태 및 출현빈도는 이용객의 영향범위의 판단에 유의한 기준이었으며 소나무림야영장이 혼효림야영장보다 훼손범위가 넓었고, 훼손형태별 출현빈도는 거리 및 수관층위에 따라 달랐다. 토양함수량, 토양산도, 토양경도. 하층수관의 피복도, 100$m^2$당 출현수종수, 개체수, 상층 및 중층의 흉고단면적 등의 인자는 야영장에서 임내방향으로 거리가 멀어짐에 따라 유의한 회귀관계를 보였으며, 야영장에서의 이용간섭의 영향범위는 70~80m이상이었다. 야영행위에 대한 내성수종으로는 고추나무, 산뽕나무, 국수나무, 광대싸리 등이 파악되었다.