• 한국안전학회지
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• 제23권2호
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• pp.21-29
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• 2008

To evaluate the structural integrity of the NPP containment building more rigorously, the effective prestress, which is one of the most affecting elements, needs to be estimated exactly. This paper presents the results of an experimental study to determine the effective prestress force in prestressed concrete beams. It is possible to improve the effective prestress measuring method by test beam, which is being applied for the investigation of the nuclear power plant in operation. If experimentally evaluated Lift-Off method in this study can be coupled with test beam test currently being used in in-service nuclear power plant, it is possible to measure prestress loss of the tendon and the level of the effective prestress load.

• 한국안전학회지
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• 제6권4호
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• pp.73-80
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• 1991

Interest in fracture of structure has increased significantly over the past decade. New approaches to analyze structural performance have been accompanied by the development of test methods to characterize material behavior in a manner compatible with the analysis. Several test methods have been developed as a results of advances in fracture mechanics, for example, $K_{IC}$ , $J_{IC}$, R-curve tearing instability and CTOD approaches. Among the rest, fracture toughness $K_{IC}$ and $J_{IC}$ can be used as an effective design criterion in fracture mechanics. Generally, the determintion of $J_{IC}$ was performed according to ASTM E 813 or JSME S 001 and $K_{IC}$ was performed according to ASTM E 399. In this study, the test method for $K_{IC}$ and $J_{IC}$ were discussed.scussed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.467-470
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• 2005

This study was performed to evaluate the static strength of long-span PSC deck slabs. In the previous study, the minimum thickness of PSC deck slabs in the composite two-girder bridge was proposed. To examine the structural behavior and safety of the PSC deck slabs designed in accordance with the proposed minimum thickness, 1/3 scaled PSC deck slabs in the composite two-girder bridge were tested under the static loading. The test results were compared with the predicted values proposed by the code and Matsui. Test results showed ultimate static strength of the PSC deck slabs designed in accordance with the proposed minimum thickness have enough margin of safety. The static failure mode of each test specimen was punching shear mode.

• 한국안전학회지
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• 제15권3호
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• pp.102-107
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• 2000

The extensive use of pretensioned prestressed concrete in the modem construction industry, together with wider application of pretensioned components for structural purposes requires some important consideration on the adequate transfer of prestress force into the concrete, especially around the end zones of pretensioned member. The main objective of this paper is to study the effects of various important parameters on the bond characteristics of prestressing strand around the end zone of high strength pretensioned concrete members. To this end, a comprehensive experimental program has been set up. The principal test variables considered were strand diameter, concrete strength, concrete cover size. The present study provides valuable test data for the realistic and accurate determination of transfer length, which can be efficiently used for improving the design equation of transfer length in pretensioned prestressed concrete members.

• Safety and Health at Work
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• 제12권2호
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• pp.192-200
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• 2021

Background: A number of accidents have occurred in small and medium enterprises (SMEs). Efforts in reducing accidents have been undertaken through the implementation of safety behaviors. Unfortunately, few studies have examined motives behind unsafe behaviors, such as safety silence motives. This study aimed to observe the motives underlying safety behaviors, namely safety silence motive (SSM) (SSM-relation, SSM-climate, SSM-issue, and SSM-job) and to evaluate the effect of SSM and safety communication on safety participation in different industrial sectors and scales. Materials and Methods: Eighty workers from two industrial sectors and scales of SMEs were involved. They were instructed to fill out a set of questionnaires. A five-Likert scale was used to respond. An independent t test was applied to find any significant differences. The partial least square-structural equation modeling for multigroup was used to develop a model on relations among the variables. Results: The results showed that SSM scores were high in SMEs, and the scores were different across industrial sectors and scales. SSM had a negative influence on safety communication, and safety communication positively influenced safety participation. Conclusion: The study of SSM, safety communication, and safety participation in different sectors and scales should be separated in SMEs.

• Nuclear Engineering and Technology
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• 제56권5호
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• pp.1887-1894
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• 2024

Fatigue strength of the structural materials of lead-cooled fast reactors (LFRs) and accelerator-driven systems (ADS) may be degraded in liquid metal (Lead or lead-bismuth eutectic (LBE)) environments. The fatigue crack growth (FCG) data of structural materials in liquid LBE are necessary for damage tolerance design, safety assessment and life management of key equipment. A novel monitoring system for fatigue crack length was designed on the compliance method and the monitor technology of crack opening displacement (COD) of CT specimens by the linear variable differential transformers (LVDT) system. It can be used to predict the crack length by monitoring the COD of CT specimens in harsh high-temperature liquid LBE using a LVDT system. The prediction accuracy of this system was verified by FCG experiments in room temperature air and liquid LBE at 150, 250 and 350 ℃. The first results obtained in the FCG test for T91 steel in liquid LBE at 350 ℃ are presented.

• 한국구조물진단유지관리공학회 논문집
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• 제14권6호
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• pp.220-228
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• 2010

일체형 삼각 트러스 형태의 철선을 아연도금 강판에 용접한 철선일체형 데크 플레이트는 슬래브 시공 시 현장시공 최소 및 동바리와 지보공 등 거푸집 공사비 절감을 목적으로 개발되어 이미 많은 현장에 적용되고 있다. 본 연구에서는 철선일체형 데크 플레이트 시스템의 구조성능 평가를 위해 상부철선, 하부철선, 래티스 철선, 경간, 단부가공방법을 변수로 채택하여 총 32개의 시험체를 실물크기로 제작하여 실험적 연구를 수행하였다. 연구결과 시험체의 최종파괴형태 변화 및 단부가공방법이 시험체의 구조 성능에 영향을 미치지 않는 것으로 나타났으며, 경간 3.2m 시험체는 래티스 철선으로 ${\Phi}4.5$를 사용해도 큰 무리가 없는 것으로 나타났다.

• 한국기계가공학회지
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• 제16권2호
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• pp.1-6
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• 2017

In this paper, we present a study concerning the design of a 400 N class side thruster for small ships. The side thrusters used in Korea are imported from abroad. The performance and durability of the imported products employed in Korea are not adequate, therefore the side thrusters which will be suitable for Korean domestic needs to be re-designed. The strength calculation of the side thruster was performed by KS standard. Strength calculation and design were made to meet design requirements. Structural analysis and safety factor analysis were carried out to confirm the validity of strength calculations and design. After manufacturing the bevel gear, a back lash test was conducted. We also conducted a no-load test, a rated load, and an overload test for a performance test and a durability test of the design while satisfying the design conditions.

• 자연, 터널 그리고 지하공간
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• 제1권2호
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• pp.59-71
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• 1999

Recently, many deformations in tunnel such as crack and leakage were occulted. Specially, the defects of tunnel lining have been a serious problem in safety and stability many repair works for maintenance in tunnel have been carried out. Therefore, it is necessary to estimate the structural cracking for countermeasure in deformed tunnel and to investigate on the characteristics of lining system and the soundness of tunnel. In this study model tests for tunnel lining were carried out using test apparatus and centrifuge, In the direct loading test, the prototype was Kyungbu high-speed railway tunnel and the scale is 1/10, and lining models were made of concrete. Test conditions included load conditions such as direction, shape and type, lining conditions such as single and double lining, thickness, and reinforcement. In centrifuge model test, the prototype was Seoul subway tunnel and the scale is 1/100, and lining models were made of aluminum and hydrostone. Test conditions included tunnel defects such as thickness shortage. behind cavity and longitudinal cracks, reinforcement methods such as epoxy, grouting and carbon sheet. From these model tests , the characteristics of deformation and failure for tunnel lining were estimated, and the structural behaviors of deformed lining and the effects of repair and reinforcement for tunnel lining were researched.

• 한국항공우주학회지
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• 제42권4호
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• pp.336-343
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• 2014

깃끝단 후퇴각을 가지는 현대 터보프롭 항공기의 최신 프로펠러는 고속으로 비행할 수 있는 추력을 얻기 위해 구조적으로 높은 강도가 요구된다. 본 연구에서는 프로펠러 구조 설계 시 고강도 및 고강성의 특성을 지닌 카본/에폭시 복합재료가 적용되었으며, 경량화를 위하여 스킨-스파-폼 샌드위치 구조 형태를 채택하였다. 구조 설계를 위한 구조 하중은 블레이드에 작용하는 공력하중을 분석하여 결정하였으며, 스파 플렌지는 굽힘 하중을 담당하고 스킨은 전단 하중을 담당하도록 복합재료 설계 개념을 반영하였다. 구조 안전성을 평가하기 위하여 상용 유한 요소 해석 코드인 나스트란을 활용하여 구조 해석을 수행하였다. 시제품 블레이드의 구조 시험을 통하여 적용된 구조설계 방법론이 적절함을 확인하였다.