• Journal of the Korean Geotechnical Society
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• v.39 no.2
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• pp.5-17
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• 2023

In this study, a classification and uniaxial compression test of soil was conducted on 15 collapsed sites to use ground improvement with excellent protection effect owing to the increase of localized heavy rain in Korea. The Casagrande method and fall cone test were performed on the field soil to derive an expression for comparing liquid limit and plastic limit values, soil classification, and correlation between each other. By deriving the optimal mixing ratio of the ground improvement agent using uniaxial compressive strength for each soil classification, the classification of the fine-grained soil was not clear owing to the proficiency difference and test error. However, after classifying using the fall cone test, it was possible to suggest a clear optimal mixing ratio.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.442-446
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• 2003

연약지반으로 분류되는 조간대 퇴적층의 연구는 제한적인 시추자료에 의존하고 있다. 비파괴 지반조사 방법은 시추자료에서 획득할 수 없는 지층의 측방변화와 지질 이상대를 확인할 수 있는 대안이 될 수 있다. 지구물리탐사 방법은 현장 토질조사와 같이 직접적인 지반조사 방법과 병행할 경우 지반을 이해하는데 있어 한층 나은 결과를 얻을 수 있다. 부산신항 배후부지 조성지역에서 매질의 상이한 특성에 기초한 비파괴 지반조사 방법으로 이용되는 지구물리탐사를 실시하였다. 각 탐사의 결과는 서로 유사한 지층경계를 나타내며, 시추와 매립공사의 결과와도 일치한다. 또한 계측을 위해 매설된 침하판이나 매설관로의 탐지, 압밀차이에 의한 부등 침하의 측방변화 등과 같이 시추조사에서 인지하기 어려운 부분에 대한 정보를 제공하고 있다.

• Journal of the Korean Geographical Society
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• v.33 no.2
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• pp.191-208
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• 1998

제주도의 기온온난화가 한라산 고산식물 분포에 미치는 영향에 대한 연구의 하나로 한라산 고산식물 8종의 수평 및 수직 분포역과 생육환경이 조사되었다. 그 결과 희귀하거나 멸종 위기 상태에 있는 고산식물들에 관한 생물지리학적 기초 자료와 정보가 축적되었다. 한라산 고산식물은 분포특성에 따라 8가지 유형으로 분류되며, 그 중 70퍼센트 정도가 한반도의 고산지나 일본열도의 것들과 공통적인 것으로 밝혀졌다. 이들은 빙하기 동안 동북아시아에서 한반도를 거쳐 제주도로 유입되었고, 일부는 일본열도에 전파된 것으로 생각된다. 현재 이들 고산식물은 열악한 기후, 척박한 토질과 지질 그리고 동결과 융해가 반복되는 주빙하성 환경에 적응하여 산정부 일대에 주로 분포한다. 본 연구는 한라산 고산식물의 분포와 과거 및 현재 환경과의 관계에 대한 기초 자료를 구축하여, 한반도의 자연환경 변천사를 파악하고, 기온온난화가 지속될 때 한라산 고산경관과 생태계가 당면할 문제를 파악하고 대안을 제시하는데 필요한 정보를 제공할 것으로 기대된다.

• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.487-498
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• 2004

There is an increasing trend of construction works in mountainous areas by the urban development in Busan that is mainly composed of mountains. The study area, Hwangryeong Mt., is one of developing sites in the urban area, too. Landslides and cut-slope failures that occur large damages of human beings and the properties are influenced by soil characteristics as well as rock properties. This study analyzed geotechnical characteristics of soil dependent on geology at Hwangryeong Mt. where a large slope failure had been occurred in 1999. Geology of the study area is composed of the Cretaceous sedimentary rocks and volcanic rocks. Soil layer of the slopes can be grouped into sand mixed with clay and silt. The cohesion is plotted between $0.001\;and\;0.066kg/cm^2$. The friction angles are distributed in the ranges between $32^{\circ}\;and\;39^{\circ}$, meaning soil bearing a high friction angle. The permeability coefficients are plotted between $2.34\times10^{-4}cm/sec\;and\;2.58\times10^{-2}cm/sec$, indicating fine sand and loose silt with a medium grade of permeability. The sedimentary rocks area shows relatively higher permeability coefficients than those volcanic rocks area.

• Journal of the Korean GEO-environmental Society
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• v.18 no.12
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• pp.37-45
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• 2017

Structural instability and damage are caused by frost heave during the winter when atmospheric temperature maintains below $0^{\circ}C$. Frost heave is the most representative engineering characteristics of frozen ground and there are various frost susceptibility criteria. Frost susceptibility criteria can be roughly divided into three categories. First, frost susceptibility is determined from particle size distribution, which is practically useful and many countries are adopting. In this paper, several particle size distributions (PSDs) are applied to the frost susceptibility criteria but PSD seems to be not enough to determine whether soils are frost susceptible. Second, it is judged from laboratory frost heave testing results. Laboratory frost heave tests were performed with newly developed thermal controlled triaxial cell and the reliability of frost susceptibility criteria is evaluated. New testing apparatus and method are suitable to meet the existing frost susceptibility criteria. Third, it is compositive frost susceptibility criteria envelope including the particle size distribution, soil classification, and frost heave test. The compositive frost susceptibility criteria envelope should be supplemented based on additional data on various soil types.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5C
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• pp.293-301
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• 2008

Soil profiling is one of the most important work among geotehnical engineering practice. Generally, soil profile is estimated from the observation of soil samples during subsurface exploration but such estimation also includes some experiencing aspects such as flushed water from the borehole, slime colour, boring speed and so on. In addition, since the capacity of hydraulic drill rig is significantly increased, thin layers might be easily missed. So, continuous soil profile is almost impossible over all depth to be bored from conventional subsurface exploration. While CPT or CPTu can serve continuous soil profile information over all depth generally in 5cm interval. Many charts or methods for soil profile from CPT result have been proposed during last several decades over the world. However they have not been verified in local ground condition in Korea. In this research, CPT results and soil classification results based on USCS were compiled from 17 sites over the Korea. Soil classification results by using 7 CPT soil classification charts were compared with those of USCS for the compiled database. Most proper CPT soil classification chart for Korean soil characteristics was evaluated and effective parameters for the soil classification from CPT were discussed. Finally interrelationship between CPT soil classification chart and USCS soil classification was evaluated.

• Journal of Korean Society of Forest Science
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• v.89 no.2
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• pp.275-284
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• 2000

This study was carried out to analyze the mechanical properties of soil and the slope stability on the fill slope of forest road constructed in the regions which consist of igneous and metamorphic rock area. The results were summarized as follows. 1) Soil type by Unified Soil Classification System(USCS) was classified as SW in soil slope, GP in weathered rock slope, GP in soft rock slope for both types of parent rock, but gravelly soil slopes in igneous and metamorphic rock area were classified as SP and GW, respectively. 2) Dry unit weight was $1.34g/cm^2{\sim}1.59g/cm^2$, specific gravity 0.57~0.61, and void ratio 0.66~0.93 in the case of igneous rock area, a dry unit weight was $1.35g/cm^2{\sim}1.51g/cm^2$, specific gravity 2.67~2.77, and void ratio 0.78~1.01 in the case of metamorphic rock area. 3) The strength parameters such as internal friction angle(${\phi}$) and cohesion(c) were selected and tested for slope stability analysis. ${\phi}$ and c of soil in igneous rock area were within the range of $29.51^{\circ}{\sim}41.82^{\circ}$ and $0.03kg/cm^2{\sim}0.38kg/cm^2$, respectively, and $21.43^{\circ}{\sim}41.43^{\circ}$ and $0.05kg/cm^2{\sim}0.44kg/cm^2$ in metamorphic rock area, respectively. 4) Result of the slope stability analysis of forest road showed that, in the weathered rock slope of igneous rock and the weathered rock and soil slope of metamorphic rock area, the possibility of slope failure was high as safety factor was below 1.0.

• Journal of the Korean GEO-environmental Society
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• v.17 no.2
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• pp.13-22
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• 2016

Accurate settlement estimation of dredged soft soil deposits is significantly important to prevent potential disasters during land reclamation. An application of the non-linear finite strain consolidation theory is inevitable in dealing with a very soft ground formation such as dredged fill. In this paper, a series of the sedimentation-consolidation test, self-weight consolidation test and CRS test were conducted to clarify sedimentation and consolidation characteristics of dredged fill in the Songdo area, Incheon. In addition, the settlement of dredged fill was numerically simulated using the PSDDF program. The dredged soil obtained from the Songdo area was classified as low-compressible silt (ML) based on USCS (Unified Soil Classification System), and the final bulking factors were estimated to be 1.56 and 1.17 by Yano's method and the numerical simulation, respectively. This difference is attributable to relatively high reclaimed height and large permeability of dredged soil in this region.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.428-428
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• 2011

댐은 우리사회에 다양한 이익을 제공하는 반면 과거의 댐 붕괴 사례에 비추어 볼 때 붕괴로 인한 피해 규모는 막대하다. 세계 각국에서는 기존 댐들에 대한 잠재적 붕괴에 대비하기 위해 비상대처계획(Emergency Action Plan, EAP)과 같은 대책을 수립하여 붕괴로 인한 피해를 최소화하기 위한 노력을 기울이고 있다. 댐붕괴 모델링은 크게 댐 결괴부에 대한 예측과정과 댐 붕괴로 인한 하류부 홍수추적 과정으로 분류할 수 있다. 결괴부 예측과정은 댐붕괴로 인한 저수지 유출량에 가장 큰 영향을 미치는 부분이며 하류부 영향지역의 평가에도 매우 중요한 요소이다. 댐붕괴 예측모형은 결괴부에 대한 예측에 따라 매개변수 기반 모형과 물리기반 모형으로 분류된다. 매개변수 기반모형은 결괴형성과정을 단순 시간에 의한 함수로 고려하고 있으며 결괴부를 통한 흐름은 위어흐름으로 가정하고 있다. 이 모형은 현재 댐 붕괴 실무에서 가장 널리 이용되고 있으며 대표적인 모형은 FLDWAV/ DAMBRK 모형, HEC-RAS 모형 등이 있다. 물리기반 모형은 댐 붕괴진행 과정의 상세한 이해를 위해 시작되었으며 결괴부 흐름상황, 제체 침식, 제체가 불안정해지는 과정을 수리실험과 수리학, 토질역학, 구조역학 등의 이론을 통합하여 예측하는 기법으로 댐붕괴 과정을 좀 더 현실적으로 예측할 수 있으며 기존 붕괴된 댐들에 대한 붕괴 원인 및 진행과정을 규명할 수 있는 장점을 가진다. 최근 개발된 물리기반 댐 붕괴 모형은 HR-BREACH 모형, WINDAM 모형, FIREBIRD 모형 등이 있으며 지속적으로 연구되고 있다. 본 연구에서는 현재 진행 중에 있는 물리기반 댐 붕괴 모형들을 검토하고 현재 USDA, ARS에서 개발 중에 있는 WINDAM 모형을 이용하여 물리기반 모형의 수행에 요구되는 입력변수, 수행과정, 결과물에 대한 검토를 통해 댐 붕괴 관련 연구의 발전 방향을 모색하고 국내에서 물리기반 댐 붕괴 모형을 적용하기 위해 요구되는 사항과 한계점을 파악하여 댐 붕괴 실무로의 적용 방안을 마련하는 데 그 목적이 있다.

• Journal of Korean Society of Forest Science
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• v.84 no.2
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• pp.166-177
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• 1995

This study was carried out to discuss how soils in the area planned for a forest road construction can be mechanically tested and practically applied. For this, 16 soil test samples from 8 plots(2 samples per plot) were used. The major tests are focused on unit weight before and after cut, water content, liquid and plastic limits, sieve and hydrometer analysis etc. The total unit weight(${\rho}_t$) before and after cut are $1.69g/cm^3$ and $1.19g/cm^3$, respectively. Their water contents are 21.0% and 20.5%. The coefficient of uniformity U and coefficient of curvature C obtained from sieve and hydrometer analysis are 125 and 0.42, which mean generally not well graded. On the soil classification by USCS, SM(silty sand or silt-sand mixed soil)is a Key soil, but it seems to be not good for fill material. From the standard proctor test are resulted $1.40{\pm}0.065g/cm^3$ for the unit weight(${\rho}$) in the nature and $1.88{\pm}0.049g/cm^3$ for the optimum proctor unit weight(${\rho}pr$) each. With this to say, it is necessary more powerful compaction work at earth filling, with which this soil reachs enough the ${\rho}pr$, and more earth.