• Proceedings of the KSEEG Conference
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• 2001.04a
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• pp.171-174
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• 2001

• Journal of The Korean Radiological Technologist Association
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• v.28 no.1
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• pp.299-300
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• 2002

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.761-768
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• 2012

The purpose of this study is to investigate bond properties of GFRP used in SFRC (Steel fiber reinforced concrete) and normal concrete. The experimental variables were rebar diameter (D13, D16), steel fiber volume fraction (0~2%) and cover thickness ($1.5d_b$, $5.4d_b$). The experimental results showed a different failure mode depending on the cover thickness. Through the tested specimens, splitting failure occurred for the specimens with small cover thickness and pull out failure occurred in the specimens with large cover thickness. Introduction of steel fiber caused the specimens to have more ductile behavior of bond stresss-lip after peak stress, but they did not increase the bond strength significantly. These failure modes were shown in both steel reinforcement and GFRP. However, from the difference of micro structure of bond failure mechanism between steel rebar and GFRP rebar, more ductile behavior was observed in GFRP-specimens after maximum bond strength was reached.

• Journal of Korea Water Resources Association
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• v.46 no.1
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• pp.1-12
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• 2013

In this study, the potential effects of increased water temperature on fish habitat were analysed in the streams of Nakdong River watershed. The changes in suitable habitats for each fish species and in species number at a habitat site were predicted, based on the maximum thermal tolerances of 22 fish species. The estimated maximum thermal tolerance ranged between $27.7^{\circ}C$ and $33.1^{\circ}C$. Then, the increase of water temperature in 78-sites of Nakdong River watershed by 2100 was predicted by using the estimated air temperature data by 2100 in the literature and the regression analysis between air-temperature and water-temperature at each sites. The water temperature was estimated to have increased by $0.69^{\circ}C$, $1.76^{\circ}C$, and $2.32^{\circ}C$ in 2011~2040 (period S1), 2041~2070 (S2), and 2071~2100 (S3), respectively. With such increases in water temperature, the averaged suitable habitats for all 22 fish species would be influenced by 21.9%, 36.3%, and 51.4% in periods S1, S2, and S3, respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.3
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• pp.38-46
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• 2023

In this study, a bearing test was performed and analytically evaluated to evaluate the bearing performance according to the application of the aluminum stiffener in round-end concrete. In the bearing strength test, the change in bearing performance due to the aluminum stiffener using the aluminum form for manufacturing concrete with round-end, and the steel anchor bolts for member movement and assembly was confirmed. The FE analysis model was identically configured to the experimental conditions, and the result was compared with the experiment. Also, the crack patterns and stress behavior were confirmed. In addition, the effect of strength change of the aluminum stiffener on the round-end concrete was also evaluated analytically. The bearing strength of the round-end concrete increased by about 20% due to the aluminum stiffener, and it was confirmed that the steel anchor bolt did not affect the bearing strength. The maximum load and crack patterns shown as a result of FE analysis were similar to those of the experiment. As a result of FE analysis according to the strength change of the aluminum stiffener, the maximum load change according to the increase and decrease of the strength of the aluminum stiffener by 10% and 20% was evaluated to have no significant effect at a maximum of about 4% compared to before the strength change.

• Computational Structural Engineering
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• v.11 no.1
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• pp.58-69
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• 1998

본 기사에서는 진동을 유발하는 기계장치의 지지 형태에 따른 해석 모델링 기법을 소개하는데 중점을 두었다. 다양한 해석 모델등 중 어느 것을 사용할 것인가는 주어진 조건이나 정보, 요구되는 정확도, 효율성 등을 고려하여 설계 엔지니어가 판단하여야 한다. 또한 진동 하중을 받는 구조물에 대한 설계 및 해석을 하기 위해서는 기계장치에 대한 사양 및 요구사항, 지반의 물리적 성질, 외부 환경적 요인 등을 파악하여야 한다. 종합적인 판단하에 구조물을 모델링하여 얻어진 결과들을 가지고 실제 설계 요구 조건과 비교, 검토를 하여야 하며, 이러한 설계 조건들은 다음과 같은 사항들을 포함한다. 1) 지반이나 구조물의 파괴, 과도한 처짐 등에 대한 정적 강도를 검토한다. 2) 진동 응답에 대한 최대 변위, 최대 속도, 최대 가속도를 검토한다. 3) 최대 확대계수, 최대 동적하중 계수, 공명조건, 최대 전달계수 등을 포함한 동적 거동을 검토한다. 4) 실제 구조물에서 일어날 수 있는 모든 모드들에 대한 검토를 한다. 5) 기계, 구조물, 연결부 등에 대한 파괴 가능성을 고려한다. 6) 사람이나 기계장치의 작동 등에 대한 환경적 요구조건의 만족 여부를 검토한다.

• Journal of the Korea Concrete Institute
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• v.28 no.1
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• pp.33-40
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• 2016

The KCI-12 and ACI 318-14 design codes limit the maximum yield strength of shear reinforcement to prevent concrete compressive crushing before the yielding of shear reinforcement. The maximum yield strength of shear reinforcement is limited to 420 MPa in the ACI 318-14 design code, while limited to 500 MPa in the KCI-12 design code. A total of eight post-tensioning prestressed concrete beams with high strength shear reinforcement were tested to observe the shear behavior of PSC beams and the applicability of the high strength reinforcement was thus assessed. In the all PSC beam specimens that used stirrups greater than maximum yield strength of shear reinforcement required by the ACI 318-14 design code, the shear reinforcement reached their yield strains. The observed shear strength of tested eight PSC beams was greater than the calculated ones by the KCI-12 design codes. In addition, the diagonal crack width of all specimens at the service load was smaller than the crack width required by the ACI 224 committee. The experimental and analytical results indicate that the limitation on the yield strength of shear reinforcement in the ACI 318-14 design code is somewhat under-estimated and needs to be increased for high strength concrete. Also the application of high strength materials to PSC is available with respect to strength and serviceability.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.437-438
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• 2010

This study was carry out to evaluate the effect of flexural behavior according to using hybrid steel fiber in UHPC. The evaluation of the flexural behavior of UHPC using hybrid fibers showed that the admixing of hybrid steel fibers at a volumic ratio of 2% increased the flexural strength by more than 27% (maximum 50%) compared to the use of steel fibers only. A ratio of 1.5% was seen to provide flexural strength exceeding the current strength of UHPC.

• Journal of the Korean Geotechnical Society
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• v.17 no.5
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• pp.51-60
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• 2001

연안역 굴양식장에서 발생하여 폐기물로 분류되어 불법으로 버려지는 굴패각을 파쇄하여 혼합한 모르타르 혼합토의 특성을 규명하고자 압축강도 시험을 포함한 다양한 실내시험을 수행하였다. 압축강도시험을 위하여 준비한 모르타르 공시체는 시멘트, 물, 모래 및 굴패각을 다양한 배합비로 혼합하여 제작하였다. 강도시험결과에 따르면 분쇄한 굴패각의 비율이 최대 모래중량의 40%까지 혼합한 경우에도 굴패각을 섞지 않은 일반 모르타르 혼합토에 비하여 압축강도가 크게 감소하지 않았다. 본 연구에서 수행한 압축강도실험을 분석한 결과, 다양한 크기로 파쇄한 굴패각을 적절한 혼합비의 모래 및 시멘트와 배합하여 사용한다면 건설재료로서의 재활용 가능성이 충분한 것으로 판단되었다.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.729-734
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• 1995

원자력용 316L강에 질소를 첨가한 경우의 고온 인장성질을 조사하였다. 온도가 증가하면 인장강도는 감소하다가 온도범위가 30$0^{\circ}C$~50$0^{\circ}C$에서는 일정한 값을 나타낸 후 급격한 감소를 나타내었고 연신율은 감소하다가 40$0^{\circ}C$에서 최소값을 나타낸 후 다시 증가하는 경향을 나타내었다. 질소를 첨가하면 인장강도증가와 함께 연신율도 증가하였다. 동적변형시효 온도구간에서 변형속도변화에 따른 인장강도 및 연신율의 변화는 매우 작다. 동적변형시효를 위한 활성화에너지를 구해본 결과 동적변형시효를 일으키는 원소는 Cr이다. 질소를 첨가하면 동적변형시효가 발생되는 온도가 고온 쪽으로 이동되었는데 이것은 질소가 Cr과의 상호작용에 의해 Cr의 확산속도를 낮추기 때문이다. 가공경화지수는 동적변형시효와 회복의 영향으로 40$0^{\circ}C$에서 최대값을 나타내었으며 이 온도는 연신율이 최소값을 나타내는 온도와 인장강도가 일정하게되는 온도와 일치하므로 강도강화기구는 동적변형시효로 판명되었다.