• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.884-893
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• 2019

Spent fuel racks are steel structures used in the storage of the spent fuel removed from the nuclear power reactor. Rack units are submerged in the depths of the spent fuel pool to keep the fuel cool. Their free-standing design isolates their bases from the pool floor reducing structural stresses in case of seismic event. However, these singular features complicate their seismic analysis which involves a transient dynamic response with geometrical nonlinearities and fluid-structure interactions. An accurate estimation of the response is essential to achieve a safe pool layout and a reliable structural design. An analysis methodology based on the hydrodynamic mass concept and implicit integration algorithms was developed ad-hoc, but some dispersion of results still remains. In order to validate the analysis methodology, vibration tests are carried out on a reduced scale mock-up of a 2-rack system. The two rack mockups are submerged in free-standing conditions inside a rigid pool tank loaded with fake fuel assemblies and subjected to accelerations on a unidirectional shaking table. This article compares the experimental data with the numerical outputs of a finite element model built in ANSYS Mechanical. The in-phase motion of both units is highlighted and the water coupling effect is detailed. Results show a good agreement validating the methodology.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.27-28
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• 2023

Currently, the Off-Site Construction (OSC) construction method, which emphasizes the minimization of field work, is being emphasized at construction sites due to the lack of construction skilled manpower, extreme weather, and the Severe Disaster Punishment Act. In this study, we developed a stacked PC modular, which is a method of stacking PC modules, and solved the lifting problem by reducing the weight of the unit module, which is emerging as the biggest disadvantage of PC modules, to around 20 tons. For the connection between modules, structural safety was secured through repeated history tests of the wall and slab connection. Walls and slabs satisfied all statutory fire resistance times through fire resistance tests, and residential performance was evaluated to be satisfactory through mock-up demonstration. The developed PC modular has been applied to the construction of commercial houses, detached houses, shopping malls, churches, etc., and has design results for many buildings such as dormitories, detached houses with 4 floors or more, and resorts, so it is expected that an atmosphere of revitalization of construction methods will be created.

• Fire Science and Engineering
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• v.22 no.1
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• pp.93-98
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• 2008

Full-scale fire extinguishment tests were conducted to develop loaded stream fire extinguishing systems for protecting underground transmission cables. The dimension of test mock-up was 5.5m height${\times}3m$ width ${\times}6m$ length, and six 154kV OF cables were piled up. Gasoline was used to ignite cates. Linear heat detection cables were installed on top of 154 kV OF cable and discharge nozzles were installed on the top and sidewalls, respectively. As a result, both surface fires and deap-seated fires were extinguished successfully within the specified 3 minutes by discharging loaded stream agent.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.173-178
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• 2016

When a ballast track of a high-speed train is constructed on a bridge, the displacement of the bridge decks can occur because they are not fixed to the rails. Moreover, relative displacements occur between the bridge and rails caused by temperature changes and external loads. The current longitudinal resistance criteria (UIC Code 774-3, KR C-08080) on ballast tracks with continuous welded rails (CWRs) do not take into account the longitudinal movement of the bridge and the frictional force between the ballast and slabs. In addition, the magnitude of the longitudinal resistance, k, is calculated somewhat conservatively and, (therefore?) it acts as an unfavorable element in the design of long span and continuous railway bridges. Thus, in order to replicate the actual behavior more effectively, the longitudinal resistance of CWRs should take into account the additional rigidity between the slab and track. In this study, the longitudinal resistances of the ballasted track on the bridge were analyzed by carrying out an experimental study with a test setup designed to simulate the deck and bed track. In the test results, the maximum longitudinal resistances of the tests were similar to the resistances of the current codes, however, the measured longitudinal stiffness designed to limit the displacement of the tests were much smaller in comparison with the longitudinal stiffness on the codes.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.21-32
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• 2002

Small and full scale model tests were performed to obtain the transient responses of shafts subjected to elastic impact by impact-echo test. Four end conditions of drilled shafts were considered: (1) free, (2) fixed, (3) rock-socketed, and (4) soft bottom. In small scale model tests, mock-up shafts were fabricated to simulate these four drilled shafts using poly-urethane and plastic material. Additionally, skin frictions between shaft and rock were changed to find out the effect of side contact on dynamic responses. All impact responses were tested in the air. Subsequently, full scale model tests were also carried out on concrete shafts that were in free and rock-socketed condition. The end conditions of the drilled shafts could be identified with good reliability by the waveforms from both small and full scale model tests. The results obtained in this study will provide an improved understanding of the impact responses for end conditions, especially for rock-socketed drilled shafts that are frequently designed and built in Korea.

• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.613-620
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• 2004

We encapsulate the core materials which have long term resisting properties to the insect. We also try to apply those capsules to the mortar and concrete which is used for the structures and ornament materials. Various membrane structures and sizes of microcapsule are tested and construction properties of the mortar and concrete which contain microcapsules are examined. The capsuled are confirmed by SEM and optical microscope. Finally the microcapsules with anti-insect which can be used for the mortar and concrete are developed through the various experiments and mock-up tests.

• Journal of the Korean Geotechnical Society
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• v.16 no.3
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• pp.131-144
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• 2000

본 연구는 비검측공 시험법으로서 널리 사용되고 있는 충격반향기법(impact-echo test)의 적용서을 수치해석 및 실내 실험을 통하여 분석해 보았다. 즉, 결함이 없는 말뚝과 결함이 있는 말뚝에 대하여 1차원 및 2차원 축대칭 유한요소해석을 실시하였으며, 또한 모노캐스트라고 하는 일종의 플라스틱 원형 봉의 말뚝에 축대창 공극, 비축대칭 공극, 병목부 및 단면 확대부와 같은 결함을 각각 크기와 깊이를 변화시켜 제작한 후 공기 중과 지반 내부에서 충격반향기법 실험을 수행하였다. 실험결과 충격반향기법의 말뚝 결함 탐지능력은 수치해석에서 얻은 결과와 함께 결함의 크기와 위치에 영향을 받는 것으로 나타났으며 결함의 크기가 커질수록 탐지의 정확도가 향상되는 것을 알 수 있었다. 결함의 상대면적이 말뚝 단면적의 50% 이상이면 충격반향기법에 의하여 결함의 위치를 파악할 수 있는 것으로 나타났으며, 공기 중 보다 지반에 근입 된 말뚝의 경우가 더욱 명확한 신호를 제공해주는 것으로 나타났다. 그리고 시간영역의 신호가 주파수 영역의 신호 보다 말뚝의 결함 크기에 더 민감히 반응하므로 주파수 영역에서 탐지할 수 없는 작은 크기의 결함을 시간 영역에서는 탐지할 수 있는 것으로 나타났다.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.14 no.1
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• pp.58-65
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• 2018

The purpose of this study is to develop a Half Nozzle Repair(HNR) process to prevent the leakage from welds on small bore piping in Reactor Coolant System. The Codes & Standards of tempered bead and design requirements of J-Groove welds are reviewed. Automatic machine GTAW welding and machining equipments are developed to perform HNR process. Single pass welding and overlay welding equipments are conducted in order to obtain the optimal temper bead welding process parameters with Alloy 52M filler wire. Coarse grain heat affected zone(CGHAZ) is formed by rapid cooling rate in heat affected zone after welding. Accordingly, a proper temper bead technique is required to reduce CGHAZ in 1-Layer of welds by 2- and 3-Layers. Mock-up tests show that the developed HNR process is possible to meet ASME Code & Standard requirements without any defect.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.4
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• pp.322-327
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• 2013

Recently many people have been troubled with perennial allergic rhinitis. But there is no way to cure for root of it until now. Therefore many medical treatments to release symptoms of perennial allergic rhinitis have been researched. One of them is localized aerosol hyperthermia, which injects $42^{\circ}C{\sim}43^{\circ}C$ vapor into nasal cavity. Vapor inhalator for localized aerosol hyperthermia has been researched in foreign country. But on the other hand it has rarely been researched inside of the country. Since most clinics and hospitals have used imported vapor inhalator, it is needed to develop domestic vapor inhalator. In the paper, a superior vapor inhalator compared to former developed one is developed. The superiority of it comes from direct-vapor heating instead of water heating to control vapor temperature. The developed vapor inhalator has shorter rising time than the existing one because of direct-vapor heating. Furthermore vapor generation part and control part of the vapor inhalator developed as one piece mock-up. It enables the vapor inhalator to have smaller size. Many laboratory tests are performed and compared to existing results to prove its performance.

• Journal of the Korea Institute of Building Construction
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• v.9 no.1
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• pp.49-55
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• 2009

In this study, reduction methods of surface air void were examined for high performance concrete having high viscosity. The effects of assumed influencing factors such as form types, form-coating materials, tamping equipments and methods were examined based on the tests on mock-up specimens made of high performance concrete. The test results can be summarized as follows: As for form types, the most favorable results were obtained when coated plywood form was used with panel-shape tamping equipments at the contact region with concrete, the second and the third being the water/air-permeable sheets and steel with coated plywood, respectively. As for tamping equipments, a vibrator with 6.5cm diameter was most effective. Finally, the shorter the tamping intervals, the better the reduction effect of surface air void. As a conclusion, an improved method was proposed to reduce surface air void and it was verified with the test result that only four air voids as large as $5{\sim}10mm$ are found in the are of $1m^2$.