• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.226-229
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• 2008

To investigate an in-pile behavior of the newly developed DUO fuel pellet, the irradiation test will be carried out in the domestic test reactor. Irradiation test capsule for the HANARO reactor, which is a specially designed equipment used for material, irradiation and creep test, must satisfy the operational requirement on the hydraulic characteristics and structural integrity. In this study, a pressure drop, a flow-induced vibration and a short-term endurance test for the newly developed non-instrumented test capsule were carried out using FIVPET as a out-pile evaluation test. The test results show that the new test rig satisfy the HANARO operational requirement with sufficient margin.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.121-127
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• 2001

To investigate the stability and integrity of offshore structures, it is necessary to estimates the significant ocean environmental loadings. They include hydrostatic pressure, wind, wave, current, tide, ice, earthquake, temperature, marine growth and scouring. Waves are of major importance among them because of the large forces acting on submerged parts of the structure caused by accompanying water motions. For the comparison of stress and deflection analysis tools, a vertical pile is applied under environmental loads. The analysis is concerned with SACS(Structural Analysis Computer System), ANSYS and C program. SACS and C program have nearly the same results but not ANSYS. This study shows the comparison of results obtained from 3 different approaches.

• Earthquakes and Structures
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• 제18권4호
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• pp.407-421
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• 2020

In-place analysis for offshore platforms is essentially required to make proper design for new structures and true assessment for existing structures, in addition to the structural integrity of platforms components under the maximum and minimum operating loads when subjected to the environmental conditions. In-place analysis have been executed to check that the structural member with all appurtenance's robustness have the capability to support the applied loads in either storm or operating conditions. A nonlinear finite element analysis is adopted for the platform structure above the seabed and pile-soil interaction to estimate the in-place behavior of a typical fixed offshore platform. The SACS software is utilized to calculate the dynamic characteristics of the platform model and the response of platform joints then the stresses at selected members, as well as their nodal displacements. The directions of environmental loads and water depth variations have significant effects in the results of the in-place analysis behavior. The most of bending moment responses of the piles are in the first fourth of pile penetration depth from pile head level. The axial deformations of piles in all load combinations cases of all piles are inversely proportional with penetration depth. The largest values of axial soil reaction are shown at the pile tips levels (the maximum penetration level). The most of lateral soil reactions resultant are in the first third of pile penetration depth from pile head level and approximately vanished after that penetration. The influence of the soil-structure interaction on the response of the jacket foundation predicts that the flexible foundation model is necessary to estimate the force responses demands of the offshore platform with a piled jacket-support structure well.

• Nuclear Engineering and Technology
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• 제37권4호
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• pp.317-326
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• 2005

The burning-out of excess plutonium from the reprocessing of spent nuclear fuel and from the dismantlement of nuclear weapons is recently emphasized due to the difficulties in securing the final repository for the spent fuel and the necessity to consume the ex-weapons plutonium. An irradiation test in the Halden reactor was launched by the OECD Halden Reactor Project (HRP) to investigate the in-pile behavior of plutonium-embedded fuel as a form of mixed oxide (MOX) and of inert matrix fuel (IMF). The first cycle of irradiation was successfully accomplished with good integrity of test fuel rods and without any undesirable fault of instrumentations. The test results revealed that the MOX fuel is more stable under irradiation environments than IMF. In addition, MOX fuel shows lower thermal resistance due to its better thermal conductivity than IMF. The on-line measured in-pile performance data of attrition milled MOX fuel are used in the analysis of the in-pile performance of the fuel with the fuel performance code, COSMOS. The COSMOS code has been developed for the analysis of MOX fuel as well as $UO_2$ fuel up to high burnup and showed good capability to analyze the in-reactor behavior of MOX fuel even with different instrumentation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1415-1426
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• 2008

Stone columns, locally called "GCP (granular compaction pile)" can be used to improve strength and resistance against lateral movement of a foundation soil like rigid piles and piers. Also installation of such a discrete column facilitates drainage, and densifies and reinforces the soil in the sense of ground improvement. The integrity of the GCP has been indirectly controlled with the records of each batch including depth and the quantity of stone filled. An integrity testing was attempted using crosshole S-wave logging. The method is conceptionally same as the crosshole sonic logging (CSL) for drilled piers. The only and critical difference is that S-wave should be used in the logging, because P-wave velocity of the stone column is less than that of ground water. The crosshole sonic logger does not have the capability to measure S-wave propagating through the skeleton of crushed stone. An electro-mechanical source, which can generate either P- or SH-waves, and a 1-D geophone were used to measure SH-waves. Two 76mm diameter cased boreholes were installed 1 meter apart across the nominal 700mm diameter stone column. At every 10cm of depth, shear wave was measured across the stone column. One more borehole was also installed 1 meter outward from the one of the above boreholes to measure the shear wave profile of the surrounding soil. The diametric variation of the stone column with respect to depth was evaluated from the shear wave arrival times across the stone column, and shear wave velocities of crushed stone and surrounding soil. The volume calculated with these variational diameters is very close to the actual quantity of the stone filled.

• 한국지반공학회논문집
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• 제40권4호
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• pp.179-188
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• 2024

많은 시설물의 기초로 사용되고 있는 현장타설말뚝의 시공 건전성을 확인하기 위하여 비파괴 건전도 시험이 사용되고 있다. 그러나 비파괴 건전도 시험은 내부 결함의 유무로만 기초의 안전성을 파악하며 결함의 위치 및 규모는 고려하고 있지 않다. 따라서, 본 연구에서는 말뚝 기초 결함의 단면 특성을 추출하고 횡방향 지지력 및 단면력을 검토하는 BIM 연계 횡방향 지지력 해석 모델을 제안하고, 이를 이용하여 결함이 존재하는 현장타설말뚝 기초의 안전성을 평가하고자 한다. 해석 결과, 상부에 존재하는 결함이 말뚝머리 변위 변화에 많은 영향을 끼쳤으며 결함에 의한 발생 휨모멘트 변화보다는 단면 축소로 인한 PM 상관도의 크기 감소가 부재 파괴의 위험도를 더 증가시키는 것을 확인하였다. 이러한 제안 방법은 현장타설말뚝의 입체적인 안전성 평가에 도움이 될 것으로 판단된다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 1999년도 제2회 학술발표회
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• pp.202-216
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• 1999

대형구조물일수록 깊은 기초를 사용하게 된다. 깊은 심도, 대구경의 기초일수록 제자리 기초공법을 채택하는 경우가 많은데 이 때는 적합한 콘크리트의 품질검사와 품질확인 작업이 요구된다. 이를 위해 콘크리트 건전도 시험이 수행된다. 또한 구조물의 개보수 공사 혹은 안전진단시 기초의 건전도와 근입깊이에 대한 정보가 필요하다. 그러나 여러 사정에 의해 기초의 근입깊이를 알 수 없는 경우가 많으므로 이를 알아내기 위한 기법도 요구된다. 음파검층, 탄성파탐사 기법이 이러한 기초구조물의 건전도 시험에 응용되고 있다. 송수신 분리형의 수평검측법은 시공시 매설된 복수의 검측공에서 적용되어 매우 정확한 건전도시험을 수행할 수 있으며, 단일채널 반사법 탄성파탐사는 제자리 기초는 물론 기성말뚝에 대한 건전도시험도 가능하다. 정확도는 검층법이 더 우수하다. 깊은 기초의 근입깊이 조사를 위해서는 평행탄성파법, 시추공레이다법, 시추공자력탐사가 적용될 수 있다.

• 한국지반공학회논문집
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• 제34권4호
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• pp.27-35
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• 2018

본 연구의 목적은 현장타설말뚝에 발생한 네킹 결함을 평가하기 위해 전자기파의 적용성을 검증하는데 있다. 본 연구에서는 네킹 결함이 있는 직경 150mm, 길이 270mm의 소형 모형 말뚝에 대해 실험을 수행하였다. 말뚝에 모사된 결함은 총 4개이며, 이 중 두 개의 결함은 모형 말뚝의 서로 다른 면의 상부와 하부에 각각 모사되었으며, 나머지 두 개의 결함은 같은 면의 상부와 하부에 모사되었다. 전선을 철망을 이루고 있는 스테인리스 재질의 철사를 따라 설치하여 두개의 도체로 구성된 전송선로를 구성하였으며, time-domain reflectometer를 이용하여 전자기파를 송 수신하였다. 실험 결과, 모형 말뚝의 결함부와 선단부에서 전자기파의 반사 신호가 나타났다. 측정된 반사 신호로부터 결함의 위치를 산정한 결과, 실제의 결함 위치와 거의 같게 산정되었다. 본 연구의 결과는 전자기파가 현장타설말뚝의 네킹 결함을 평가하는데 있어 유용한 기법이 될 수 있음을 보여준다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.281-286
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• 2007

Needs of fuel's performance evaluation for the dual-cooled fuel pellet (annular shape) necessitate the irradiation test in the test reactor. Irradiation test rig for the HARARO reactor, which is a special-purposed equipment used for material, irradiation and creep test, must satisfy the operational requirement on the hydraulic characteristics and structural integrity. In this paper, pressure drop and flow-induced vibration test for the newly developed non-instrumented test rig were carried out using FIVPET as a out-pile evaluation test. The test results show that the new test rig satisfy the HANARO operational requirement with sufficient margin. The spectral response characteristics of the flow-induced vibration of the test rid were also discussed.

• 자연, 터널 그리고 지하공간
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• 제21권2호
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• pp.117-129
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• 2019

Tunnelling in urban environments is very common nowadays as large cities are expanding and transportation demands require the use of the underground space for creating extra capacity. Inevitably, any such new construction may have significant effects on existing nearby infrastructure and therefore relevant assessment of structural integrity and soil-structure interaction is required. Foundation piles can be rather sensitive to nearby tunnel construction and therefore their response needs to be evaluated carefully. Although detailed three-dimensional continuum finite element analysis can provide a wealth of information about this behaviour of piles, such analyses are generally very computationally demanding and may require a number of material and other model parameters to be properly calibrated. Therefore, relevant simplified approaches are used to provide a practical way for such an assessment. This paper presents a simple method where the pile is modelled with beam finite elements, pile-soil interaction is modelled with soil springs and tunnelling-induced displacements are introduced as an input boundary condition at the end of the soil springs. The performance of this approach is assessed through some examples of applications.