• Nuclear Engineering and Technology
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• v.48 no.1
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• pp.246-258
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• 2016

The shield building of AP1000 was designed to protect the steel containment vessel of the nuclear reactor. Therefore, the safety and integrity must be ensured during the plant life in any conditions such as an earthquake. The aim of this paper is to study the effect of water in the water tank on the response of the AP1000 shield building when subjected to three-dimensional seismic ground acceleration. The smoothed particle hydrodynamics method (SPH) and finite element method (FEM) coupling method is used to numerically simulate the fluid and structure interaction (FSI) between water in the water tank and the AP1000 shield building. Then the grid convergence of FEM and SPH for the AP1000 shield building is analyzed. Next the modal analysis of the AP1000 shield building with various water levels (WLs) in the water tank is taken. Meanwhile, the pressure due to sloshing and oscillation of the water in the gravity drain water tank is studied. The influences of the height of water in the water tank on the time history of acceleration of the AP1000 shield building are discussed, as well as the distributions of amplification, acceleration, displacement, and stresses of the AP1000 shield building. Research on the relationship between the WLs in the water tank and the response spectrums of the structure are also taken. The results show that the high WL in the water tank can limit the vibration of the AP1000 shield building and can more efficiently dissipate the kinetic energy of the AP1000 shield building by fluid-structure interaction.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.1
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• pp.7-13
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• 2013

Bio Clean Room(BCR) and pharmaceutical product manufacturing facilities require careful assessment of many factors, including HVAC, controls, room finishes, process equipment, room operations, and utilities. Flow of equipment, personnel, and product must also be considered along with system flexibility, redundancy, and maintenance shutdown strategies. It is important to involve designers, operators, commissioning staff, quality control, maintenance, constructors, validation personnel, and the production representative during the conceptual stage of design. Critical variables for room environment and types of controls vary greatly with the clean space's intended purpose. It is particularly important to determine critical parameters with quality assurance to set limits and safety factors for temperature, humidity, room pressure, and other control requirements. In this paper, oxygen cluster ion equipment was utilized in order to enhance the indoor air quality and to prevent the airborne infection of ward in hospital. Moreover, the performance test of the equipment was also performed in order to develop the optimal sterilization system of BCR using the equipment.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.04a
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• pp.47-60
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• 1998

It is considered in this paper that the main causes of tunnel collapse during the construction were the insufficiency of data of geotechnical investigations, or their limits due to special ground condition such as its heterogeneity and anisotropy It is thought that safety of ground can be affected by the geological conditions such as presences of discontinuities in good intact rocks, and considered to be necessary that awareness of the conditions of discontinuities in advance is important to apply adequate reinforcement measures. It is also shown that a serious accident had occurred because of the unawareness of the permeable alluvial deposits at the top of the tunnel. And it is shown that the example of application of the results of geotechnical investigation such as face-mapping, pilot boring etc. during tunnel construction, and a serious deformation of tunnel under special geological condition. Therefore, it is strongly recommended to perform an adequate geotechnical investigation to confirm the geotechnical conditons of ground before design, and supplimentary investigation is also needed depending on conditions for safe and econonic construction.

• Journal of the Korean Geotechnical Society
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• v.28 no.9
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• pp.31-45
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• 2012

This study was conducted to estimate the stability of a quay wall in case of wave overtopping under the combined action of an earthquake and tsunami using limit equilibrium method. The tsunami force was calculated by using a numerical program called TWOPM-3D (3-D one-field Model for immiscible TWO-Phase flows). Especially, the wave force acting behind the quay wall after a tsunami wave overtopping was estimated by treating back fill as a permeable material. The stability of the quay wall was assessed for both the sliding and overturning modes under passive and active conditions. The variation in the stability of the quay wall with time was determined by parametric studies, including those for the tsunami wave height, seismic acceleration coefficient, internal friction angle of the soil, wall friction angle, and pore water pressure ratio. When the earthquake and tsunami were considered simultaneously, the tsunami induced wave overtopping increased the stability of the quay wall under the passive condition, but in the active condition, the safety factors decreased.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.2
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• pp.165-170
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• 2015

Pipe-rack structures supporting high temperature and pressure are of great importance to ensure the safety of the operation of the plants. If some damage occurred in the pipe-rack structure, the facilities not only bring damage to the commercial property, but also result in economic losses. Specially, since pipe-rack structures are exposed to various environmental conditions, it is essential to evaluate the thermal behavior of the structure caused by environmental conditions for the appropriate design and maintenance of the pipe-rack structure. Thus, based on a selected, typical pipe-rack structure, a thermal-stress coupled analysis was conducted to evaluate the temperature distributions and thermal stresses of the structure. For this, this study accounted for the operating condition of the pipe and the effect of environmental conditions, Yeosu in South Korea and Saudi Arabia in the Middle East. The results of the study showed the need for accounting for a variance in the environmental factors to evaluate the thermal behavior of the pipe-rack structure along with the working condition of pipe.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.9 s.252
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• pp.1034-1040
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• 2006

Due to the need of increasing thermal efficiency, supercritical pressure and temperature have been utilized in power plants. It is well known that 9Cr1Mo steel is suitable fer use in power plants operating at supercritical conditions. Therefore, to ensure the safety and the soundness of the power plant, creep characterization of the steel is important. In this study, the creep characterization of the gCr1Mo steel using small punch creep(SP-Creep) test has been described. The applied load and the central displacement of the specimen in SP-Creep test have been converted to bearing stress and strain of uc, respectively. The converted SP-Creep curves clearly showed the typical three-stage behavior of creep. The steady-state creep rate and the rupture time of the steel logarithmically changed with the bearing stress and satisfied the Power law relationship. Furthermore, the Larson-Miller parameter of the SP-Creep test agreed with that of the tensile creep test. From the comparison with low Cr-Mo steels, the creep characteristics of 9Cr1Mo steel proved to be superior. Thus, it can be confirmed that the 9Cr1Mo steel is suitable for supercritical power plant.

• Transactions of the KSME C: Technology and Education
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• v.5 no.2
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• pp.127-134
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• 2017

The reactor internals shall be secured in safety and structural integrity under various vibrational loading conditions. Thus, U.S. NRC, Regulatory Guide 1.20 requires the evaluation for the reactor internals due to acoustic induced vibration including the response to the reactor coolant pump pressure pulsation. This paper suggests a methodology to develop an analytical model of the core support barrel accounting for the fluid around the structure and to analyze the responses to the pump pulsation loads using acoustic structure interaction analysis. The analysis results were compared with those of US Palo Verde 1 CVAP and showed a good agreement. Thus, it is expected that the suggested methodology could be an efficient way to evaluate the response of the core support barrel to the pump pulsation loads.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1663-1672
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• 2018

In recent times, gas insulated medium voltage (MV) circuit breakers (CB) form a vital component in power system network, considering its advantages such as reduced size and safety margins. Gas insulation characteristics of circuit breakers are generally measured by lightning impulse (LI) test according to IEC standard 60060-1 as a factory routine test. Considering the environmental issues of $SF_6$ gas, many research works are being carried out towards the mixture of $SF_6$ gases for high voltage insulation applications. However, few reports are only available regarding the LI withstand and streamer propagation characteristics (at both positive and negative polarity of waveform) of $SF_6/N_2$ gas mixture insulated medium voltage circuit breakers. In this paper, positive and negative polarity LI tests are carried out on 22 kV medium voltage circuit breaker filled with $SF_6/N_2$ gas mixture at different gas pressures (1-5 bar) and at different gas mixture ratios. Important LI parameters such as breakdown voltage, streamer velocity, time to breakdown and acceleration voltage are evaluated with IEC standard LI ($1.2/50{\mu}s$) waveform. Weibull distribution analysis of LI breakdown voltage data is carried out and 50% probability breakdown voltage, scale parameter and shape parameter are evaluated. Results illustrate that the $25%SF_6+75%N_2$ gas filled insulation considerably enhances the LI withstand and breakdown strength of MV circuit breakers. LI breakdown voltage of circuit breaker under negative polarity shows higher value when compared with positive polarity. Results show that maintaining the gas pressure at 0.3 MPa (3 bar) with 10% $SF_6$ gas mixed with 90% $N_2$ will give optimum lighting impulse withstand performance of 22 kV MV circuit breaker.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.161-166
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• 2020

In accordance with the amendment of the Industrial Safety and Health Act of 2007, Korea completely prohibited the import, distribution and manufacture of asbestos like Europe and Japan. Accordingly, the current problem of asbestos is the safe maintenance and disposal of asbestos construction material, the disposal of asbestos, and the final disposal of asbestos building materials. If the asbestos building material is made harmless, it may be classified as general waste or as recyclable waste. Therefore, this study evaluated the physical and chemical characterization of detoxified asbestos powder and the applicability of secondary products. In this study, it was found that applying the appropriate temperature and pressure for catalysis during asbestos desalination through low temperature chemical treatment was the most important factor.

• Journal of the Korean Institute of Gas
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• v.4 no.3 s.11
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• pp.53-58
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• 2000

It was carried out consequence analysis(CA) of CNG (compressed natural gas) service station and we compared the results of CA of CNG service station with LPG service station which was installed by high Pressure gas law. The results of CA were that distance of CNG LFL was 1.5 times than the length of LPG LFL. Thermal radiation effect about CNG may not be showed damage of process facilities, but in the case of LPG, it was enough to have an large damage effect on a downtown. The thermal radiation of 37.5 $kw/m^2$ extended 12.6 m. Also, in the case of 12.5 $kw/m^2$ which was able to burn wood, the radiation effect of LPG is 3 times than CNG.