• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1050-1056
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• 2008

Many cut slopes are situated on national highways. In this study, we chose rock slopes of moderated weathering grade to analyze general strength parameters of cut slopes. We analyzed the strength parameters of selected rock slopes by the experience method. Also, we arranged the strength parameters by area and rock types.

• Computers and Concrete
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• 제24권3호
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• pp.249-258
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• 2019

In order to investigate the strength recovery of fire-damaged concrete after post-fire curing, concrete specimens were heating at $2^{\circ}C/min$ or $5^{\circ}C/min$ to 400, 600 and $800^{\circ}C$, and these exposed specimens were soaked in the water for 24 hours and following by 29-day post-fire curing. The compressive strength and split tensile strength of the high-temperature-exposed specimens before and after post-fire curing were tested. The proportion of split aggregate in the split surfaces was analyzed to evaluate the mortar-aggregate interfacial strength. After the post-fire curing process, the split tensile strength of specimens exposed to all temperatures was recovered significantly, while the recovery of compressive strength was only obvious within the specimens exposed to $600^{\circ}C$. The tensile strength is more sensitive to the mortar-aggregate interfacial cracks, which caused that the split tensile strength decreased more after high-temperature exposure and recovery more after post-fire curing than the compressive strength. The mortar-aggregate interfacial strength also showed remarkable recovery after post-fire curing, and it contributed to the recovery of split tensile strength.

• 한국재난정보학회 논문집
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• 제13권1호
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• pp.35-42
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• 2017

본 연구에서는 연약지반이나 부분침하의 복원에 사용되는 팽창약액의 강도특성을 정량적으로 평가하기 위하여 팽창성능을 구분한 팽창약액을 제작하여 강도특성을 조건에 따라 분석하였다. 상대적 고팽창군과 저팽창군으로 구분하여 실험을 실시하였으며, 각각 최대 팽창부피에 대해 10~30%의 부피를 제어한 공시체를 제작하여 강도 평가를 수행한 결과 시간에 따라 강도가 증진되는 것을 확인하였고, 고팽창군과 저팽창군의 압축강도는 약 2.1배의 차이를 보였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.97-104
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• 2008

The objective of this study was to investigate the strength characteristics of frozen clay. Compressive strength tests were performed on frozen clay with different water contents at various temperatures. The dry density of specimens and strain rate was kept constant. Test results showed that compressive strength increased with increasing water content and decreasing temperature. The increase in peak strength became more significant the lower the temperature for a given water content. The failure mode changed from brittle to ductile deformation with increasing water content and decreasing temperature. Tests also showed an increase in deformation modulus with increasing peak strength, increasing water content and decreasing temperature.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1555-1558
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• 2008

In this paper, result of whole test, When the Transfer Distance is increasing, Strength of Backfilling Material of NATM Composite lining Tunnel due to increasing Gravity was increased, but that is higher the Air Flotation than increasing Strength. So, That was predicted a drop of Permeability. And Performing the placing Lightweight Foamed Mortar, we think that it's performance in drain material was lost. Therefore We conclude that Proper Transfer Distance that taking Permeability through minimizing of Air Flotation Loss and getting the Need Strength is 50m.

• 한국재난정보학회 논문집
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• 제2권1호
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• pp.129-137
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• 2006

The present work is attempt to evaluate the temperature dependence of blast furnace slag concrete(BFSC) based on the concrete strength cured with different curing temperatures and ages. A equivalent substitution index(ESI) was induced to explain temperature dependence of concrete quantitatively as well as concrete strength. The results from compressive strength showed substantial crossover effect. which is the phenomenon that the compressive strength cured at low temperature becomes stronger than the one cured at high temperature. The crossover effect found more definitely on BFSC than plain concrete.. The ESI became 1.1 and 1.0 for the BFSC cured at $20^{\circ}C$ and $30^{\circ}C$ after age of 56 days, respectively. Which means that the contribution to strength development of blast furnace slag per unit mass is stronger than that of the Portland cement. It was considered therefore that the optimum curing temperature for BFSC is $20^{\circ}C$.

• Structural Engineering and Mechanics
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• 제52권5호
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• pp.889-901
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• 2014

Very long life fatigue tests were carried out on 16Mn steel base metal and its welded joint by using the ultrasonic fatigue testing technique. Specimen shapes (round and plate) were considered for both the base metal and welded joint. The results show that the specimens present different S-N curve characteristics in the region of $10^5-10^9$ cycles. The round specimens showed continuously decreasing tendency while plate specimens showed a steep decreasing step and an asymptotic horizontal one. The fatigue strength of round specimen was found higher than plate specimen. The fatigue strength of as-welded joint was 45.0% of the base material for butt joint and 40% for cruciform as-welded joint. It was found that fracture can still occur in butt joint beyond $5{\times}10^6$ cycles. The cruciform joint has a fatigue limit in the very long life fatigue regime ($10^7-10^9$ cycles). Fatigue strength of butt as-welded joint was much higher as compared to cruciform as-welded joint. Improvement in fatigue strength of welded joint was found due to UPT. The observation of fracture surface showed crack mainly initiated from welded toe at fusion areas or geometric discontinuity sites at the surface in butt joint and from welded toe in cruciform joint.

• Geomechanics and Engineering
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• 제30권3호
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• pp.281-291
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• 2022

Complex rock masses include various joint planes, bedding planes and other weak structural planes. The existence of these structural planes affects the mechanical properties, deformation rules and failure modes of jointed rock masses. To study the influence of the parameters of a nonpersistent joint network on the mechanical properties and failure modes of jointed rock masses, synthetic rock mass (SRM) technology based on discrete elements is introduced. The results show that as the size of the joints in the rock mass increases, the compressive strength and the discreteness of the rock mass first increase and then decrease. Among them, the joints that are characterized by "small but many" joints and "large and clustered" joints have the most significant impact on the strength of the rock mass. With the increase in joint density in the rock mass, the compressive strength of rock mass decreases monotonically, but the rate of decrease gradually decreases. With the increase in the joint dip angle in rock mass, the strength of the rock mass first decreases and then increases, forming a U-shaped change rule. In the analysis of the failure mode and deformation of a jointed rock mass, the type of plastic zone formed after rock mass failure is closely related to the macroscopic displacement deformation of the rock mass and the parameters of the joints, which generally shows that the location and density of the joints greatly affect the failure mode and displacement degree of the jointed rock mass. The instability mechanism of jointed surrounding rock is revealed.

• 한국건설순환자원학회논문집
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• 제11권2호
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• pp.105-111
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• 2023

본 연구에서는 초기 재령에서 NSH(Non-sintered Hwangto) 치환율에 따른 고강도 콘크리트의 역학적 특성을 평가하였다. NSH의 치환율은 15 % 및 30 %로 설정했다. 평가 항목은 압축강도와 UPV(Ultrasonic pulse velocity)로 설정하였으며, 최종적으로 UPV분석을 통해 압축강도 예측 방정식을 제안하였다. 압축강도와 UPV에서는 NSH 치환율이 증가할수록 낮은 강도 및 UPV를 보였다. 또한 압축강도와 UPV의 상관관계 분석 결과, 상관계수(R2)는 NC33(Normal concrete)은 0.99, NSHC(Non-sintered Hwangto Concrete)33-15는 0.97, 그리고 NSHC33-30은 0.94로 높은 상관관계를 나타냈다.

• 한국재난정보학회 논문집
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• 제8권4호
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• pp.336-346
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• 2012

최근 발생된 일련의 재난빈도가 과거에 비하여 빈번히 발생됨에 따라 실제 재난에 따른 공공피해액 이외에 사유재산에 의하여 발생되는 피해 또한 증가하고 있는 실정이다. 그러나 사유재산 피해액의 경우 전체 피해규모 산정 시 포함되어야 함에도 불구하고 산정방법 부재로 인하여 실질적으로 포함되지 않고 있다. 본 연구는 사유재산 피해액 산정기준 및 조사 방법을 연구하며 실제 재난발생 시 효율적인 총 피해산정을 통한 포괄적인 재난대책 준비가 가능하고자 보다 세부적인 사유재산 피해요소들을 분석, 다양한 산정방안들을 제시하고자 한다. 이를 위하여 기존 국내외 사유재산 피해조사 및 산정에 관련된 내용들을 우선적으로 조사하였으며 이를 통한 현행 조사방법의 문제점을 분석하여 보다 효율적인 사유재산 피해액 산정방법 등을 제시하였다. 최종적으로 본 연구를 통하여 국민들의 피해 체감지수를 최소화하고 보다 공정하고 효율적인 자연재해 총 피해액 산정 및 조사방법을 체계적으로 구성하였으며 또한 특별재난지역선포기준 등과 같은 포괄적인 재난강도 평가지수 등의 사유재산 피해액에 관련된 기준 개선에 관한 기초 안을 제시하였다.