• Journal of Korean Society for Geospatial Information Science
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• v.24 no.2
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• pp.113-120
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• 2016

The necessity of maritime sector for continuous management, accurate and update location information such as seabed shape and location, research on airborne LiDAR bathymetry surveying techniques are accelerating. Airborne LiDAR systems consist of a scanner and GPS/INS. The location accuracy of 3D point data obtained by a LiDAR system is determined by external orientation parameters. However, there are problems in the synchronization between sensors should be performed due to a variety of sensor combinations and arrangement. To solve this issue, system calibration should be conducted. Therefore, this study evaluates the system verification methods, processes, and operation techniques.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.2
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• pp.63-70
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• 2016

A housing market in an urban area is not just a single market but a combination of regionally different submarkets. This study begins with a critical mind that previous researches did not consider the spatial autocorrelation of each area where the housings are located. The clustering analysis of housing submarket which considers spatial autocorrelation is performed as it follows. First, 4 housing market attribute variables are reducted to 1 variable by principle component analysis. Then, after calculating $Gi^*max$ by AMOEBA, 7 housing submarkets which have similar characteristics based on $Gi^*max$ are classified. The characteristics of each submarket are investigated, then political implication is deduced as the following. Different level of housing policy should be made to each cluster because each cluster has different level of spatial autocorrelation.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1717-1726
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• 2008

Vibration triaxial compression test was put in influence for liquefaction strength of fine grained soil of dredged and reclaimed ground and consideration for fine fraction content, relative density, overconsolidation ratio and plasticity index in this study. By the results of these test, the liquefaction strength increased with fine fraction content and the relative density, overconsolidation ratio incresed with liquefaction strength too. However, in the case of nonplastic silt was the smalist liquefaction strength which influenced by dilatancy and interlocking when silt content was 34.7%(average grading 0.12mm). Therefore, liquefaction strength of fine grained soil of dredged and reclaimed ground increased with fine fraction content so it will help to make lower liquefaction.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.713-720
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• 2008

본 연구는 낙동강 하구 대심도 연약지반에 항타관입된 PHC 말뚝에 대하여 SPT 지지력 공식으로 부터 계산된 선단지지력 값과 PDA 시험에서 얻어진 선단지지력 측정값을 비교하였다. 또한, SPT N값이 50이 넘는 경우에 대하여는 N값과 롯드 관입깊이의 선형관계를 가정하여 30cm 관입깊이에 해당하는 N값을 적용한 경우와 CPT $q_c$와의 상관성을 이용하여 $q_c$값으로부터 N값을 산정한 경우의 2가지 분석을 수행하였다. 그 결과, 본 연구에서 적용한 SPT 지지력 공식 모두 측정된 선단지지력 값과 차이가 났으며, SPT 지지력 공식은 대심도 연약지반에 항타 근입된 말뚝에 대하여 실제적인 설계를 수행할 때 신뢰하기 어려운 것으로 나타났다. 또한, N>50인 경우에 대하여 N값과 롯드 관입깊이의 선형관계를 적용하는 것은 지지력을 매우 과대평가하는 것으로 나타났다.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.721-728
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• 2008

Top-Base Method is a stabilization method for light weight structures particularly in the soft ground. It is widely used for the increment of bearing capacity and the effect of restraining settlement when the bearing capacity of the ground is not enough. Top-shaped cone concrete foundations are installed in graveled laid over soft ground. The principle of the basic method is to maximize effect of dispersing the overburden pressure by increasing the contact area of the top-shaped cone. Therefore, the bearing capacity is increased and the settlement is decreased by the embedded resistance of pile part in the ground. In this paper, the plate bearing test was conducted to evaluate the feasibility of Top-Base foundation. Based on the test results, the coefficient of subgrade reaction, elastic modulus, and settlement of foundation on reclaimed land was derived.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.427-435
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• 2008

A reliability based slope stability assessment method is proposed and examined considering the variation of matric suction which is measured by a real time slope monitoring system. Mean value first order reliability method and advanced first order reliability method are used to calculate reliability indices of a slope. The applicability of methods is compared by applying them to the range of matric suctions measured by the real-time monitoring system. Sensitivity analysis is also performed to examine the contribution of random variables to the reliability index of slope. Finally, the proposed method is applied to a model slope. The results show that the reliability index of slope can be used for efficient slope management by quantifying the risk of slope in real time.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.672-679
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• 2008

During recent years, the large soft ground improvements very rapidly increase with industrial development and it is the types and scales of structure that is enlarged by degree. Then, we must enter construct equipment to improve soft ground and we fulfilled works by carrying out soft clay soil to gain trafficability for them. For improving the soft ground, we lay geotextile on soft clay ground and fill the filter sand that can drain the pore water. Then, we landfill cover soil for come by trafficability of construction tools. Ater that we penetrate vertical drain for dehydration through soft ground. there are very complicated works. For these reason we suggest the methods of soft ground improvement constructions.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1244-1250
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• 2008

The site of interest is a residence redevelopment area which has excavation construction with cut-off walls. The site is located over Dong-Mang-Bong tunnel and Seoul No. 6 subway tunnel. This study analyzed numerically the influence of vibrations from No. 6 subway tunnel to the basement of the redeveloped apartment away from the distance about 11m. Kyoung-bu highspeed railway's time history model with linearly reduced maximum acceleration is applied to take into the subway maximum speed of 75km/h. The maximum velocity of vibration for the cross section of the interest was estimated as 0.28cm/sec which satisfied the allowable standard of 0.5cm/sec for apartment and residence of Seoul.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1144-1156
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• 2008

In this paper, heaving phenomenon is analyzed by laboratory tests. A laboratory test is consist of building soft clay foundation in plane-strain soil tank, construction of retaining wall, and excavation work. And range of shear strain, and destruction shape about soft clay foundation is compared, and analyzed with results of proposal formula. Using this study, safety factor is suggested for heaving phenomenon in the construction of wall on the soft clay. Actual theory is suggested by this suggested safety factor. There are various proposal formula for heaving phenomenon. For example, Terzaghi & Peck, Tschebotarioff, Bjerrum & Eide(Experience formula) and so on. Terzaghi & Peck's proposal formula is chosen, compared with laboratory test's result and analyzed in this study. A soft clay used in study is assumed homogeneous. A Depth of foundation is enough to observe shear strain by heaving phenomenon. Retaining wall is enough hard not to have vertical displacement.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1069-1080
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• 2008

The mechanical characteristic of Lightweight Foamed Soil(LWFS) are investigated in this research. LWFS is composed of the in-suit soil, cement and foam to reduce the unit-weight and increase compressive strength. The unconfined compressive tests are carried out on the prepared specimens of LWFS with various soil types to investigate the relationship between compressive strength of LWFS and physical properties of soil. The result indicate that coefficient of gradation($C_g$) and liquid limit(LL) are more important factor affecting compressive strength than other physical properties of soil and coefficient of gradation($C_g$) and liquid limit(LL) can standard to determine the optical soil among the in-situ soils for LWFS.