• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.2
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• pp.36-43
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• 2010

In this study, the buckling loads and mode shapes characteristic of circular and non-circular(elliptical) closed composite shells were analyzed. To analyses the buckling behaviors, we develop and report an improved generalized shell element called 4EAS-FS through a combination of enhanced assumed strain and the substitute shear strain fields. A flat shell element has been developed by combining membrane element with drilling degree-of-freedom and a plate bending element. The combined influences of length, thicknesses, cross-sectional parameters, and fiber-angle on the critical buckling loads and mode shapes of circular and non-circular(elliptical) closed shells are examined.

• Journal of the Korea Concrete Institute
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• v.11 no.3
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• pp.81-88
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• 1999

In order to properly evaluate the shear strength of reinforced concrete circular columns due to the transverse shear reinforcement, the average of fractions of forces generated along the circular transverse hoops across the shear failure plane in the loading direction is calculated. For this, the center-to-center diameter of circular transverse hoops. spacing and the crack angle measured to the column longitudinal axis are considered. Using these variables, an equation representing the effective section area of circular transverse shear steel is proposed. The study result shows that the constant parameter. used for the calculation of the effective section area of circular hoops over the last 10 years, should not universally be applied any more. The use of the constant parameter may not seriously do harm to the evaluation of shear strength for circular columns with non-seismically designed transverse hoop reinforcement, since it gives slightly conservative results. However. for well-confined circular columns with close spacing or circular steel jacketing. it gives about 20% overestimation of the shear capacity contributed by the transverse hoop steel.

• The Journal of the Acoustical Society of Korea
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• v.17 no.5
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• pp.79-84
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• 1998

본 논문은 길이방향으로 조화함수 형태로 변화하는 단면적을 가진 원형단면의 탄성 막대에서 전파하는 비틂 탄성파의 전파속도에 대한 이론적 및 실험적 결과를 제시한다. 주 기적인 미소한 반경 변화를 섭동법에 의해 다루어 전파속도의 이론적 근사해를 구하였다. 그결과 전파속도는 반경 변화 폭의 제곱에 비례하는 양 만큼 감소하는 경향이 나타났다. 이 론적 경향을 검증하기 위한 실험은 자왜현상으로 비틂파를 전파시키고 나사면을 가진 탄성 도파관에서 전파속도를 측정하는 방법으로 행하였다.

• Science of Emotion and Sensibility
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• v.5 no.3
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• pp.47-52
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• 2002

The handle of fabrics including tactility and sense of visuality are closely related to the factors governing the preferences of end-users. This study shows the change of mechanical properties, thermal properties and optical properties by comparing two fabrics which are woven with circular shaped filaments and with triangular ones. The fabric mechanical characteristics required for primary hand values were evaluated with the KES-FB system. The mechanical properties measured by KES-FB system shows that fabrics made of circular filaments are greater than those made of triangular ones. The thermal properties measured by KES-F7(Thermo Labo II) system shows that the values of the initial maximum value(qmax) and the thermal conductivity(λ) are higher in the fabric made of triangular shaped ones. When the light rays tall on a surface, the fabric made of triangular filaments shows more lustrous than circular ones.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.152-159
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• 2006

An experimental research has been performed to investigate capacity of CFCST(Concrete Filled Carbon Sheet Tube) columns because column member is one of the most important structural members. Generally, two shapes of column sections, rectangular and circular shapes, are designed but the circular shape which has constant curvature was chosen for this study. Total 17 column specimens confined by carbon sheet tube were tested using 10,000kN universal test machine(UTM).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.81-81
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• 2004

등통로각압축(ECAP, Equal Channel Angular Pressing)공정은 다결정의 재료 덩어리를 두 채널(channel)이 일정하게 교차하는 형태의 금형에 통과시켜 단면적과 단면 형상의 큰 변화 없이 압출하는 성형법으로 다른 공정에 비해 상대적으로 낮은 압력으로 재료에 소성변형을 발생시켜 입자를 미세화 시킬 수 있으며, 기존의 분말야금에 의한 방법에 비해 상용재료를 포함한 광범위한 금속 및 합금에 적용이 용이한 점과 재료 내부에 기포가 거의 잔류하지 않는 점등의 장점을 가지고 있다.(중략)

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.404-407
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• 2010

본 논문에서는 비선형 동적 해석 프로그램인 AUTODYN을 이용해 기둥의 단면 형상의 변화에 따른 폭발 하중의 영향을 분석하였다. 먼저 폭발하중 산정의 타당성을 확인하기 위해 AUTODYN을 이용한 예제해석을 수행하였으며, 폭발하중에 의한 영향을 가장 효율적으로 확인할 수 있는 인자인 압력을 비교하였다. 이를 토대로 기둥 형상에 따른 폭발 저항 성능을 평가하기 위해 같은 단면적과 높이를 갖는 정사각형과 원형 기둥을 모델링 한 후 TNT의 양에 따른 폭발전후의 부피를 비교하였다. 해석결과를 비교해보면 정사각형기둥이 원형기둥보다 폭발에 대한 손상정도는 더 크지만 기둥이 절단되지 않도록 하는 저항성능이 더 우수한 것을 확인할 수 있었다. 비록 철근의 영향을 고려하지 않았지만, 이와 같은 결과를 통해 TNT의 양에 따른 기본적인 폭발거동과 대테러 설계를 위한 기둥 단면 선택시 기초적인 자료로 활용가능 할 것으로 사료된다.

• Journal of Korean Society of Steel Construction
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• v.23 no.1
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• pp.83-97
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• 2011

In this study, the seismic details of a concrete-encased, U-shaped steel beam-to-RC column connection were developed. Three specimens of the beam-to-column connection were tested under cyclic loading to evaluate the seismic performance of the connection. The test parameters were the beam depth and the column section shape. The depths of the composite beams were 610 and 710 mm, including the slab depth. For the RC columns, a square section and a circular section were used. Special details using diagonal re-bars and exterior diaphragm plates were used to strengthen the connections with the rectangular and circular columns, respectively. The test results showed that the specimens exhibited good strength, deformation, and energy dissipation capacities. The deformation capacity exceeded 4% interstory drift angle, which is the requirement for the Special Moment Frame.

• Journal of the Korean Society of Hazard Mitigation
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• v.3 no.1 s.8
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• pp.123-131
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• 2003

An experiment was carried out to investigate the mechanical behaviour of the circular hollow section reinforced concrete member with internal corrugated steel tube. A specimen, 50cm in diameter and 340cm in length, was made and tested by 3 points bending. The test load was increased slowly (quasi static) to the failure or unacceptable deformation. During the test, lateral displacement at mid point and longitudinal displacement of extreme fiber on compressive and tensile side of the specimen were measured. The measured data were analysed and compared with calculated results for the equivalent member without inserted corrugated steel tube. The comparison shows that the flexural strength and ductility of hollow section reinforced concrete members can be improved by inserting corrugated steel tubes inside.

• Magazine of korean Tunnelling and Underground Space Association
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• v.5 no.4
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• pp.6-17
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• 2003

라이닝과 굴착작업은 통상적으로 병행작업이 되며, 라이닝은 시공속도가 빠르기 때문에 공기는 주로 굴착 속도에 지배된다. 그러나 소단면/원형단면 터널에서는 작업 공간확보문제 등 제반조건에 따라 굴착과 라이닝 작업이 분리되어 라이닝 공정이 전체 공기에 커다란 영향을 끼치는 경우도 있다. 라이닝 콘크리트의 타설시기는 계측에 의해 원지반의 변위가 수렴된 것을 확인한 후 하는 것이 원칙이다. 따라서 NATM 에서는 전단면 라이닝이 일반적이다. 본 고에서는 라이닝 설비로서 사용되는 타설설비, 운반설비, 형틀설비의 총 3편으로 나누어 라이닝 기계에 대하여 설명하도록 한다.