• Proceedings of the KSR Conference
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• 2003.10b
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• pp.429-435
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• 2003

This paper presents the case studies of Tubular Roof construction Method(T.R.c.M) and Semi Shield method, which were applied to the tunnel excavation under the pre-existing railways. It was proved that T.R.c.M was an effective and safe method for the tunnel excavated in soft soil, giving little damage to the railways located a few meters above. Semi Shield was also performed successfully to bore a tunnel in soft and hard rock, minimizing the ground settlement and tilting of vulnerable fuel tanks. Site and soil conditions are also discussed, which led these relatively new methods to success. Finally, comparison of the measurement results and the design values are made to verify and improve the current design practice.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.151-155
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• 1998

The Anyang river drains a highly polluted industrial area and enters the lower part of Han river. In this preliminary study for the comprehensive understanding of geochemical behaviour of elements in the stream sediments and its implications on the river chemistry and ecology, major and trace elements in stream sediments, suspended solids and stream water were analysed to look into elemental enrichments and elemental behaviour with distance from upper part of the stream. Chemical analyses of the stream sediments show enrichements of heavy metals including Cr, Zn, Ni, Co between 10 to 100 times. Other trace elements, Cd, Pb and As are also enriched between several to 10 times, based on relative ratio with Al in fresh rock. Chemical analyses of the sediments, suspended solids and water show indications of anthroporgenic impact for the heavy metal accumulation. It was nortworth Hg is detected between 2 and 4 ppb in the water.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.497-500
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• 2003

If ground water levels of a confined fractured rock aquifer fluctuate with sea tides, individual values of hydrogeologic parameters can be determined. Tidal efficiency and time lag are first calculated from the water level data recorded at an observation device situated inland from the sea. The tidal efficiency factor of the aquifer at the seacoast is then determined from the observation in monitoring wells and used to calculate storage coefficient. Tidal efficiency factor and the tidal time lag are utilized to calculate storage coefficient and the results are compared. This method is tested in the southeastern coastal area of Busan, Korea. This is a simple and inexpensive way to test confined aquifer but the analysis should be performed according to the coastal environment.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.172-174
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• 2004

본 논문은 광산산성배수(AMD)에서 철 및 알루미늄 제거 효과가 입증되고 ARD(Acid Rock Drainage)에서의 비소제거 효과가 확인된 인회석을 침전제로 사용하여 철, 알루미늄 및 비소가 아닌 다른 중긍속의 제거효율을 알아보기 위해 도금폐수를 이용하여 실내실험을 실시하였다. 실험결과, 도금폐수의 수질분석결과에 의하면 '수질환경보존법 오염물질 배출허용기준' <가>지역 방출수 기준을 초과하는 것은 pH, Zn, Fe, Cu, Cr 및 P였다. 실험 결과 인회석 40번체 통과분-100번체 잔류분을 사용하는 것이 가장 적절할 것으로 생각되며 유속은 1kg의 인회석에 11의 도금폐수를 3시간 동안 반응시키면 경제적, 시간적 측면에서 가장 적절한 것으로 사료된다. 이 경우 pH는 1.98에서 5.30으로 증가하고 Cr, Fe, Cu 및 Zn은 각각 77.10%, 99.58%, 99.39% 및 40.77% 제거되는 것으로 나타났다. 용해율은 0.3619 g/min/kg으로 계산되었다. 그러나 3시간의 반응시간으로는 크롬 및 아연을 기준치 이하로 제거하지 못하므로 인회석 반응조를 다단계로 하는 실험을 수행해 그 결과를 평가해야 할 것이다.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.10a
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• pp.275-280
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• 2001

Although important developments have taken place since ESOPT 1974 both with respect to the test method as well as the interpretation of the results, many uncertainties still remain in the Standard Penetration Test(SPT). The main pitfall of SPT is that it has not been standardized differing from its terminology and further, the possibility of standardization is very low in practice. Therefore, lack of knowledge on the equipment and method of SPT tends to cause some errors in interpretation of the results. It Is especially important to understand this tendency in domestic design, because most foundations are designed based on SPT results only. Many researchers have made an effort to minimize the uncertainties of SPf in Korea, it is not cleary defined what the most effective method of execution and interpretation of SPT Some uncertainties which many geotechnical engineers encounter in practice are introduced to discuss about improvement of test procedure and interpretation.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.295-300
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• 2002

In this research problems of recent design methods and their improvement for SIP in domestic areas were studied by using the characteristics of load-settlement curves and bearing capacity from field loading tests. Elastic and plastic settlement for total settlement in each loading step conducted domestic areas had a tendency. From these tendency and bearing capacity determined by loading tests we can ascertain that empirical chart can be assistant tool in SIP design. It showes that SIP design using N-value in domestic area with soil condition of grarute type results in very conservative bearing capacity, to be opposed in soil with unprofitable geological condition the design can be insecure. Also, we can ascertain that Meyerhof's bearing capacity used modified N-value on tip part of pile is more applicable than recent design method where tip bearing capacity is 20NAp N-value limited to 50. These results show that modified design method can he more economic than before because of using pile's bearing capacity to tolerable load of pile material.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.337-344
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• 2006

This paper is concerned with the simplified criterion given in ASCE 4-98, for determining whether soil-structure interaction (SSI) analysis is required for seismic response analysis of nuclear power plant structures. In this study, the criterion is evaluated for a couple of example structures including an existing nuclear power plant and the Hualien large-scale seismic test building. Forced vibration analysis and seismic response analysis are carried out using the simple stick model with soil springs and an elaborated SSI analytical model. From the numerical analyses, it is found that the criterion may not allow the fixed-base analysis for bedrock with shear wave velocity of greater than 1,100m/s which is a well-known criterion for a rock site. In addition, it is indicated that peak amplification as well as the peak broadening specified in NRC RG 1.122. shall be considered to include the effects of SSI.

• Ocean Systems Engineering
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• v.14 no.2
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• pp.115-139
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• 2024

In this study, numerical study of a long, straight, side-anchored floating bridge with discrete pontoons subjected to combined earthquakes and waves is conducted. Ground motions with magnitude corresponding to 200 YRP (years return period) earthquake in South Korea are generated based on the spectral matching method from a past earthquake record in California. Several sensitivity studies are carried out for bridge end condition, for different site classes (hard rock S1 and soft and deep soil S5), and for three different excitations (earthquake only, wave only, and earthquake-wave combined). Bridge and pontoon motions, bending moments along the bridge, and mooring tensions are systematically examined through coupled time-domain simulations by commercial program OrcaFlex. The numerical results show that the impact of earthquakes on floating bridges is still of importance especially for soft soil although ground motions are less directly applied to the structure than fixed bridges.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.2
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• pp.103-109
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• 2009

Soils originated from limestone, located at the southern part of Kangwon province and Jecheon, Danyang of Chungbuk province are mainly composed of fine texture, and have different properties from soils originated from granite and granite gneiss, especially for water movement. This study was conducted for classification of hydrologic soil group (HSG) of soils originated from limestone by measuring the infiltration rate of surface soils and percolation rate of sub soils. Soils used for the experiment were 6 soils in total : Gwarim, Mosan, Jangseong, Maji, Anmi and Pyongan series. Infiltration and percolation rate were measured by a disc tension infiltrometer and a Guelph permeameter, respectively. Particle size distribution and organic matter content of the soils were analyzed. HSG, which was made by USDA NRCS(National Resources Conservation Service) for hydrology, of Gwarim series with O horizon of accumulated organic matter was classified as type A which show the properties of low runoff potential, rapid infiltration and percolation rate. HSG of Mosan series, which has high gravel content and very rapid permeability, was classified as type B/D because of the impermaeble base rock layer under 50cm from surface. HSG of Jangseong series with shallow soil depth was classified as type C/D owing to the impermaeble base rock layer under 50cm from surface. HSG of Maji series was type B, and HSG of Anmi series used as paddy land was type D because of slow infiltration and percolation rate caused by the disturbance of surface soil by puddling. HSG of Pyeongan series having a sudden change of layer in soil texture was type D because of the slow percolation rate caused a the layer.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.5
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• pp.293-302
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• 2008

The limiting factors to determine available soil depth were studied with 390 soil series in soil profile description and physicochemical data in Korean soils. The limiting factors were coarse sandy layer, gravel and skeletal layer, hardpan layer, cat clay layer, poorly drained layer, salt accumulated layer and bed rock layer so on. The soils of having limiting factors were 332 soil series, but soils without limiting factors were 58 soil series. Soils with limiting factors were, hardpan 5, slopeness 93, immature soil 29, cinder 5, sandy 42, gravel or skeletal 47, bedrock 19, high salt content 8, poorly drained soil 22, heavy clay 32, sulfate soil 3 and ash soil 27 etc. And the orders of available soil depth were immature > slopeness > ash > heavy clay > sandy > gravel or skeletal > hardpan > cindery > poorly drained > bedrock > acid sulfate soil > salt accumulated soil etc.