• The Journal of Engineering Research
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• v.5 no.1
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• pp.109-118
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• 2004

국내 건설현장에서는 성토다짐의 다짐도 확인을 위해 주로 평판재하시험(PBT)을 사용한다. 평판재하시험은 재하시험시 표층의 매우 잘 다져진 곳에 대한 지지력 계수를 획득하여 실다짐도를 과대 평가하는 결과를 초래할 수 있다. 이에 착안하여 응력도달 범위가 작은 평판재하시험을 지양하고 콘관입시험으로부터 획득되는 노상의 관입지수로부터 지반의 다짐도를 추정할 수 있는 콘관입시험기와 구동시스템 및 해석 프로그램을 개발하였다. 개발된 시스템은 다짐차량에 간편하게 부착하여 현장에서 직접 다짐도를 획득할 수 있으며 다짐도와 더불어 다져진 지반의 전단강도정수를 동시에 측정할 수 있다.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.717-721
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• 2012

유속(혹은 난류강도) 증감에 따른 floc 특성의 변화를 파악하기 위하여, 현재 연안 개발이 활발히 수행되고 있는 목포해역을 대상으로 ADCP를 이용한 층별 유속 및 부유사 농도의 연속관측이 수행되었다. 목포해역 내 대표정점에서 층별로 유속 유향 및 음파 intensity와 함께 전체 수심데이터가 5분 간격으로 측정되었으며, ADCP 음파의 intensity와 부유사 농도의 상관관계 분석을 위하여 동일 시간동안 채수기를 이용하여 water sampling(30분 간격) 또한 동시에 수행되었다. 관측시간 동안의 목포해역은 낙조류의 흐름특성을 가지며, 표층에서의 최강유속은 24.5cm/s, 유향은 대체적으로 NW~N향 사이에 분포하는 것으로 나타났다. 또한 층별 부유사 농도는 그 차이가 매우 미미한 것으로 나타났다. 본 연구를 통하여 관측된 자료들은 퇴적물의 제반 이송특성 연구를 위한 기초자료로 활용될 수 있을 뿐만 아니라, 향후 퇴적물 이송 및 수질 예측/평가를 위한 수치모형 적용시 입력자료로 유용하게 사용될 수 있을 것이다.

• 한국해양학회지
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• v.22 no.2
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• pp.63-70
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• 1987

Existing oceanographic data indicate that tidal mixing fronts generally prevail in the Eastern Yellow Sea along the Korean coast. In the Western part, these fronts seem to be much weaker. These fronts are believed to be generated mostly by spatially different tidal mixing. The geostrophic adjustment model applied to the observed density structure gives the mixed coastal water flowing northward and the offshore waters(both surface warm and bottom cold waters) flowing southward along the Korean coast. The transport of each water amounts to O(10$\^$4/)m$\^$3//sec.

• 한국해양학회지
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• v.20 no.3
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• pp.6-19
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• 1985

Hydrographic data and daily time series of longshore wind, sea level and sea surface temperature were used in order to explain why the upwelling effect in SST is especially prominent near Ulgi-Gampo although the sea level records along the whole southeast coast show a nearly uniform upwelling-downwelling response to wind. Regional difference in intensity of the wind-induced upwelling represented by the SST decrease is attributed to the combined influence of two factors; one is the baroclinic tilting of isotherms due to the East Korea Warm Current (EKWC) near the Ulgi-Gampo coast, the other is the topographic effects around the southeast coast. Baroclinic tilting effect of EKWC which is generally strongest near the coast of Ulgi to Gampo results in both of the shoaling of cold water and the westward trapping of the coldest bottom water over the shallower shelf rather than the deepest troough region off that coast regardless of the season. Therefore, becacse of the cold water ready for upwelling at the subsurface layer, SST responds very rapidly to the upwelling-favorable winds of summer only off the Ulgi-Gampo coast. Spreading isobaths from Pusan to Gempo can reinforce the upwelling of the cold bottom water and its westward trapping.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.239-249
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• 2011

The behavior of the fiber reinforced concrete (FRC) base under environmental loads was analyzed numerically as a fundamental study to develop a high structural and functional performance composite pavement system in which the base was formed using FRC and the asphalt or cement concrete surface was placed on it. A two-dimensional finite element model of the FRC base was developed and the sensitivity study was performed with the variables including slab thickness of base, thermal expansion coefficient, elastic modulus, and tensile and compressive strengths. The crack spacing and crack width were selected as representatives of the base behavior. The effects of the selected variables on the crack spacing and crack width were analyzed and the sensitive variables were determined. The results of this study could be useful to determine the optimal material properties of the FRC base for combining well with the surface materials.

• 한국해양학회지
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• v.27 no.2
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• pp.137-144
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• 1992

Picoplankton in the size range of $0.2-2.0{\;}\mu\textrm{m}$ were enumerated in the Nakdong River estuary on 17 October, 1991 by using an epifluorescence microscope. Numerous minute cells emitting yellow to orange fluorescence at various strengths were recognized and the cells were moistly spherical in shape. Picocyanobacteria seem to comprise most of the picoplankton observed. They also occurred in very polluted water. Cell densities of picoplankton were in the range of $683-3,878{\;}cells{\cdot}ml^{-1}$ at the surface water. In vertical profiles, the Numbers were maximum at subsurface and minimum at surface layer. Percentage picoplankton biomass determined by chlorophyll ranged from undetectable levels to 5.9% of the total chlorophyll. The cell density and chlorophyll a concentrations of picoplankton were relatively low in the study area compared to those of other locations in world ocean, but the study of picoplankton may be important in understanding of microbial food web in the sea.

• Journal of the Korean Geosynthetics Society
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• v.8 no.2
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• pp.55-62
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• 2009

Recently, new development projects are being carried out with the soft ground located along the West coast and the South coast. As soft grounds have complex engineering properties that the load bearing capacity is low and high compressibility, it needs to solve this problems Prior to structures are constructed by the method of improvement of soft ground. The sand mat is usually being used for improvement of soft ground as a horizontal drain material and loading base. But, as the volume is enormous and an amount of demanded sand is increased, it is state of short in supply. This paper presents the feasibility study to use of precious slag ball instead of sand mat as the replacing material through the basic soil property tests, the medium of discharge capacity test and analysis of settlement character.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.85-91
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• 2011

This study aims at evaluating feasibility of Bottom ash-mixed Foam Cement Banking(BFCB) Method on the enhancement of soft soil, which is developed to reduce self-weight of banking by applying bottom ash and foam. to cement slurry. In order to measure the behavior of soil when BFCB layer was covered to soft ground, a testing equipment for mock-up test was fabricated and phased loads were applied up to measurement of yielding and ultimate strengths as well as movement of ground particles. In addition, these measured values such as settlement and heaving were compared with ones of surface-hardening method prevailing on soil improvement. As the result through mock-up test, BFCB showed lower values of ground deformation, while wider range of deformation was observed in compare to the other method. And settlement and heaving were measured lower, which implies the method developed is very effective to applicability of soft ground.

• International Journal of Highway Engineering
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• v.1 no.2
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• pp.155-168
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• 1999

Asphalt pavement tends to rut in high temperature and to crack in cold temperature. The performance of asphalt pavement can be deteriorated by korean weather condition which has the four distinct seasons. In this study, the typical sections that may minimize rutting and fatigue were analyzed through the numerical model tests. The layered elastic theory , finite element method and visco elastic theory were utilized for these numerical model tests. From the various numerical model tests, it is found that an optimum design procedure was recommended. It was increasing the thickness of asphalt stabilized base with fixing the wearing course as 5cm the minimum specified thickness. The section was most beneficial in resting rutting and fatigue. From the analysis of the relative index on tensile strain and cost analysis, it was recommended that the thickness ratio of subbase and asphalt concrete is 1.0$\sim$2.5.

• Journal of the Society of Disaster Information
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• v.15 no.2
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• pp.206-213
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• 2019

Purpose: This study aims to develop eco - friendly paving materials using Sawdust and EPDM chips. Method: Materials are eco-friendly materials and have no environmental problems. By using EPDM chip, the walking feeling can be increased. Results: In this study, the optimum mixing ratio was calculated through mixing design test. Based on the blending ratio, the surface layer of the sidewalk is made of fine sawdust and EPDM chips. We used only sawdust of grain - 107 -size to make the base layer of the sidewalks and the surface layer of the bicycle road with the permeability and the anti - resilience, and suggested the application method through the test construction. Conclusion: This study the expected that the recent efforts of the government to reduce the elastic paving material, which is the environmentally harmful problem with the complete eco-friendly paving material, are expected to revive.