• 한국지반공학회지:지반
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• 제6권4호
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• pp.33-42
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• 1990

정적관입저항 또는 선단지지말뚝의 선단지지력을 해석함에 있어서는 유효수직응력이 기준음력으로 사용되어 왔다. 그러나 정적관입저항은 유효수직응력보다 원위치 유효수평응력에 관계된다는 것이 많은 실험연구결과로부터 보고 되었다. 이와같은 문제점을 규명하기 위하여 기 보고된 실험결과를 다시 분석하였으며 실험실에서의 관입시험이 실시되었다. 연구결과 정적관입저항은 유효수직 응력과 유효수평응력 모두에 영향을 받는 것으로 나타나고 있으며 해석시에는 평균주응력이 기준응력으로 사용되어야 함을 결론 지을 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.153-154
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• 2009

본 연구는 해안가 매립지 지하구조물의 염해저항성능 향상을 위해 개발된 고내구성 콘크리트인 PHDC(Promoted High Durability Concrete)에 대한 현장적용성에 관하여 기술하였다. PHDC는 기존해안가 매립지 지하구조물 용 콘크리트가 요구하는 수밀성 확보, 균열저항성 및 염소이온 침투 방지효과가 기존의 슬래그를 혼입한 콘크리트 보다 우수 한 것으로 조사되었고, 현장 적용시 시공성 및 품질관리가 용이 한 것으로 조사되었다. 본 연구에서는 PHDC 의 강도발현, 균열저항성 및 내염해성을 조사하였고 해안매립지 지하구조물을 Life 365 프로그램에 의한 콘크리트 구조물 수명평가를 실시하였다.

• 한국세라믹학회지
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• 제34권7호
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• pp.738-746
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• 1997

MgO clinker and two kinds of dolomite clinkers with different microstructures and CaO contents were used as starting materials, and the effects of Fe2O3 addition on the properties of MgO and dolomite were investigated in the range of 2 to 8 wt% of Fe2O3 content. Secondary phases contributed to densification of MgO-Fe2O3 and dolomite-Fe2O3 were magnesioferrite and dicalciumferrite, respectively. Sinterabilities of MgO-Fe2O3 and dolomite-Fe2O3 were directly proportional to the amount of secondary phases. Also, sinterability of dolomite itself was dependent on the microstructure of starting material including distribution of CaO and MgO as well as the addition amount of Fe2O3. The flexural strength of MgO-Fe2O3 content was almost constant. The hydration resistance of dolomite with large size of MgO and discontinuous distribution of CaO was higher than that of dolomite with small size of MgO and continuous distribution of CaO. Also, the minimum content of Fe2O3 to prevent they hydration of dolomite was about 4wt%. As increasing Fe2O3 content, the penetration resistance of MgO-Fe2O3 was improved by the increment of magnesioferrite. On the other hand, the penetration resistance of dolomite-Fe2O3 was decreased because of the increment of dicalciumferrite having low melting point.

• Smart Structures and Systems
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• 제18권2호
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• pp.197-216
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• 2016

The increased speed of a train causes increased loads that act on the track substructures. To ensure the safety of the track substructures, proper maintenance and repair are necessary based on an accurate characterization of strength and stiffness. The objective of this study is to develop and apply a cone penetrometer incorporated with the dynamic cone penetration method (CPD) for investigating track substructures. The CPD consists of an outer rod for dynamic penetration in the ballast layer and an inner rod with load cells for static penetration in the subgrade. Additionally, an energy-monitoring module composed of strain gauges and an accelerometer is connected to the head of the outer rod to measure the dynamic responses during the dynamic penetration. Moreover, eight strain gauges are installed in the load cells for static penetration to measure the cone tip resistance and the friction resistance during static penetration. To investigate the applicability of the developed CPD, laboratory and field tests are performed. The results of the CPD tests, i.e., profiles of the corrected dynamic cone penetration index (CDI), profiles of the cone tip and friction resistances, and the friction ratio are obtained at high resolution. Moreover, the maximum shear modulus of the subgrade is estimated using the relationships between the static penetration resistances and the maximum shear modulus obtained from the laboratory tests. This study suggests that the CPD test may be a useful method for the characterization of track substructures.

• 한국농공학회논문집
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• 제55권6호
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• pp.11-17
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• 2013

This study was performed to evaluate the chlorine ion penetration resistance, chemical resistance and freezing and thawing resistance used ordinary portland cement, crushed coarse aggregate, crushed sand, river sand, fly ash, limestone powder, blast furance slag powder and superplasticizer to find optimum mix design of low carbon green concrete for structures. The performance of low carbon green concrete used fly ash, limestone powder and blast furnace slag powder were remarkably improved. This fact is expected to have economical effects in the manufacture of low carbon green concrete for offshore structures. Accordingly, the fly ash, limestone powder and blast furnace slag powder can be used for offshore structure materials.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 춘계 학술논문 발표대회
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• pp.172-173
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• 2014

The study is used to verify the applicability of the sensor to monitor penetration of chloride into the concrete, like real coastal environment. After manufacturing the specimen adapt corrosion sensor for chloride penetration monitoring, chloride spray experiment was conducted. And then, It was checked the possibility of monitoring of the penetrated chloride by measuring the resistance of the corrosion sensor that was embedded in each depth of the concrete. Experimental results, it is confirmed that the corrosion resistance of the sensor was increased depending on the concentration of chloride. Therefore, it is estimated that the sensor is available for monitoring of chloride penetration.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.125-128
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• 2004

This study concerns the new estimated strength equation of concrete by penetration test. There are not only few estimate strength equations of concrete, but also many problems to apply them because of time, cost, easiness, structural damage, reliability and so on. In this study, there performed a series of penetration test with in 730days' concrete structures and proposed equations as follows; $$Linear\;:\;f_{ck}=2.95d-80.0(r^2= 69.8\%)$$ $$Quadratic\;:\;f_{ck}=0.204d^2-12.15d+193.2(r^2=83.6\%)$$ here, fck : Estimated compressive strength of concrete by MPa d: exposed probe length by mm.

• Geomechanics and Engineering
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• 제13권1호
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• pp.119-139
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• 2017

Static Penetration Test (CPT) and Dynamic Penetration Test (DPT) are commonly used in-situ tests in a routine geotechnical investigation. Besides their use for qualitative investigation (lithology, homogeneity and spatial variability), they are used as practical tools of geotechnical characterization (resistance to the penetration, soil rigidity) and modern foundation design as well. The paper aims at presenting the results of an extensive research work on the evaluation of the 1D primary consolidation settlement of saturated clayey soils on the basis of the CPT or DPT tests. The work is based on an analysis of the correlations between the tip resistance to penetration measured in these tests and the parameters of compressibility measured by the compressibility oedometer test, through a local geotechnical database in the northern Algeria. Such an analysis led to the proposal of two methods of calculation of the settlement, one based on the CPT test and the other one on the DPT. The comparison between the predicted settlements and those computed on the basis of the oedometer test showed a good agreement which demonstrate the possbility to use the CPT and DPT tests as reliable tools of computation of foundation settlements in clayey soils.

• 한국구조물진단유지관리공학회 논문집
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• 제15권1호
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• pp.215-225
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• 2011

메타카올린은 고령토나 카올린으로 알려진 카올린 광물의 풍화물로, 도자기 산업에 주로 사용되는 원료로, 일반적으로 메타카올린의 입자 크기는 시멘트보다는 작지만, 마이크로 실리카퓸보다는 크다. 본 연구에서는 콘크리트용 혼화재로 메타카올린을 사용한 콘크리트의 압축강도와 염소이온 투과저항 특성에 관한 영향에 관해 조사하였다. 메타카올린과 실리카퓸의 혼입률이 압축강도와 염소이온 투과저항에 주는 영향을 비교하기 위해 물-결합재비를 30%로 고정하고 각각 0, 5, 10, 15, 20%인 배합수준을 설정하여 비교하였다. 연구결과 메타카올린을 혼입한 콘크리트는 실리카퓸을 혼입한 콘크리트와 유사한 강도특성을 보였지만, 염소이온 투과저항성은 다소 불리한 것으로 나타났다. 따라서, 강도와 염소이온 투과저항 성능을 동시에 만족하기 위한 메타카올린의 혼입률은 10% 정도인 것으로 나타났다.

• 한국해양공학회지
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• 제33권4호
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• pp.340-349
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• 2019

In the case of a fire accident on a ship or an offshore plant, the design of the bulkhead penetration piece must be verified via a fire test procedure (FTP), as specified by the Maritime Safety Committee (MSC). The purpose of this study is to verify both the numerical analysis results and the design specifications for penetration pieces that could be applied to the A60 class bulkhead division. In this study, the FTP was carried out in accordance with the test procedure prescribed in the MSC regulation. In order to review the fire resistance performance according to the material type, bulkhead penetration pieces for the FTP were made from brass, carbon steel for machine structures (S45C), and austenite stainless steel (SUS316). In addition, spray-type insulation and mechanical fastener-type insulation were applied to investigate the fire resistance performance according to the type of insulation. To verify the heat transfer numerical analysis results for the A60 class bulkhead penetrating piece from this test study, the design specifications of the penetrating piece material and the insulation type applicable to a ship and an offshore plant were identified.