• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.12 no.1
• /
• pp.85-92
• /
• 2016

The operating temperature of VHTR components is much higher than that of conventional PWR due to high core outlet temperature of VHTR. Material requirements and technical issues of VHTR reactor components which are mainly dominated by high temperature service condition were discussed. The codification effort for high temperature material and design methodology are explained. The design class for VHTR components are classified as class A or B according to the recent ASME high temperature reactor design code. A separation of thermal boundary and pressure boundary is used for VHTR components as an elevated design solution. Key design characteristics for reactor pressure vessel, control rod, reactor internals, graphite reflector, circulator and intermediate heat exchanger were analysed. Thermo-mechanical analysis of the process heat exchanger, which was manufactured for test, is presented as an analysis example.

• Wind and Structures
• /
• v.5 no.2_3_4
• /
• pp.379-392
• /
• 2002

Numerical flow computations around an aeroelastic 3D square cylinder immersed in the turbulent boundary layer are shown. Present computational code can be characterized by three numerical aspects which are 1) the method of artificial compressibility is adopted for the incompressible flow computations, 2) the domain decomposition technique is used to get better grid point distributions, and 3) to achieve the conservation law both in time and space when the flow is computed a with moving and transformed grid, the time derivatives of metrics are evaluated using the time-and-space volume. To provide time-dependant inflow boundary conditions satisfying prescribed time-averaged velocity profiles, a convenient way for generating inflow turbulence is proposed. The square cylinder is modeled as a 4-lumped-mass system and it vibrates with two-degree of freedom of heaving motion. Those blocks which surround the cylinder are deformed according to the cylinder's motion. Vigorous oscillations occur as the vortex shedding frequency approaches cylinder's natural frequencies.

• Steel and Composite Structures
• /
• v.5 no.4
• /
• pp.327-343
• /
• 2005

The European Standards Organisation (CEN) has planned to develop a complete set of harmonized European building standards. The Eurocodes, being the design standards, form part of this total system of European standards, together with standards for fabrication and erection and product standards. After a period of experimental use of the ENV(European Pre Standard)-versions of the Eurocodes, these are now converted into official EN's (European Standards). Design of composite steel and concrete buildings and bridges is covered by Eurocode 4. An overview will be given of the historic development of Eurocode 4, the structure and contents of the EN version and the present status and planning for completion. The Eurocode treatment of some selected technical items will be presented in more detail.

• Nuclear Engineering and Technology
• /
• v.31 no.6
• /
• pp.51-65
• /
• 1999

The present review report introduces the existing analysis codes and physical modeling of two-phase flow associated with initiating event of HCDA in Liquid Metal Reactors for the effective study in the future, because the related research has not been systematically carried out in Korea compared with other areas. The description in this report is specifically addressed to the results yielded from careful review of the technical concepts on the two-phase flow modeling in the SAS2A code which was developed in ANL. The report is prepared in 2 parts based on the definite physical phenomena. The liquid slug and gas behavior models are main representations in the part (I) and (II), respectively. In this regard, it is expected that this report provide a fundamental knowledge on the two-phase flow model in LMR and, thus, contribute to establishment of the necessary HCDA analysis technology concerned with the LMR development in Korea.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.05a
• /
• pp.139-142
• /
• 2004

Nickel base superalloys are widely used for high temperature applications due to heat resisting capability and corrosion resistance at high temperatures. Superalloys with many strengthening alloying elements are frequently used in powder form to alleviate harmful effects of alloy segregation. HIP (hot isostatic pressing) and DB (diffusion bonding) as a form of solid-state bonding process is used to make turbine components, such as integrated turbine rotors. HIP/DB process requires many technical overcomes related to dimensional changes as well as microstructural control. In this research, HIP/DB process for nickel base superalloys, Udimet 720 and MM 247, were investigated with a view to control the dimensional change during the consolidation process. Simple disc-shaped cans were used to select the conceptual die design for the control of the dimensional change especially in radial direction. The change in the shape of consolidated shape was investigated using commercial FE code with constitutive equations fur low temperature plasticity deformation.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.2 no.3
• /
• pp.61-71
• /
• 1998

A performance-based seismic design method for reinforced concrete building structures being developed in Japan is outlined. Technical and scientific background of the performance-based design philosophy as well as recently developed seismic design guidelines are is presented, in which maximum displacement response to design earthquake motion is used as the limit-state design criteria. A method of estimating dynamic response displacement of the structures based on static nonlinear analysis is described. A theoretical estimation of nonlinear dynamic response considering the characteristics of energy input to the system is described in detail, which may be used as the standard method in the new performance-based code. A desing philosophy not only satisfying the criteria but also evaluating seismic capacity of the structures is also introduced.

• Journal of Advanced Marine Engineering and Technology
• /
• v.28 no.3
• /
• pp.457-465
• /
• 2004

Environmental protection on the ocean has been interested and nowadays the International Maritime Organization(IMO) has advanced on the prevention of air pollution from ships. This study presents the performance and the emission characteristics of 4 stroke marine diesel engines for generation application in D2 cycle(IMO mode). The effects of important operating parameters, such as intake air pressure. intake air temperature and maximum combustion pressure on NOx emissions were also described. Emissions measurement and calculation are processed according to IMO Technical Code. The results show that the maximum combustion pressure by fuel injection timing control and intake air temperature has strong influence on NOx emission production. But NOx emission is not affected by intake air pressure and exhaust gas back pressure.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.629-636
• /
• 2003

The purpose of this study is localization of safety relief valves for Nuclear Service through technical development with overall design, fabrication, inspection, capacity certification test and functional qualification test of safety relief valves in accordance with ASME Section III and KEPIC Code. Safety relief valve is the important equipment used to protect the pressure vessel, the steam generator and the other pressure facility from overpressure by discharging the operating medium when the pressure of system is reaching the design pressure of the system. But we're depending on technology of the other country up to the present time. Because we don‘ have our own technologies, we have been spent the great time and money on installing and repairing safety relief valve at nuclear power plant. Therefore we have to achieve the development of safety relief valves for Nuclear Service with our own technologies.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.1037-1043
• /
• 2007

The railroad systems with the ballast tracks have been widely used for a long time. But recently, the use of the slab track is being increased gradually with a technical developments. So, this paper deals with the appliance of the slab tracks on the railroad bridges. Firstly, review the design criteria of the railroad bridges related to the slab tracks for the stability and serviceability, based on DIN and EURO code. Then, perform the analysis of the railroad prestressed concrete bridges, and check whether the results of the analysis satisfy the design criteria. Finally, find the construction condition of bridges that all the design criteria are satisfied. As a result, to maintain the stability and serviceability of the bridges, bridges must have some restrictions, including a time of installation of the slab tracks. So, the construction schedule for the erection of the bridges will be carefully considered in case of the concrete railroad bridges with the slab tracks.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2003.11a
• /
• pp.239-242
• /
• 2003

Transmit diversity using STBC(Space Time Block Code) provides the same diversity gain as MRRC(Maximal Ratio Receiver Combining), when the fading channel is constant across two consecutive symbols. But, when the channel condition is changed for the two consecutive symbols, the transmit diversity using STBC does not offer good performance due to the large doppler shift. In this paper, we have proposed a interference cancellation scheme for performance enhancement in transmit diversity using STBC over time selective fading channel. Simulation results for various doppler shift rates are presented for the transmit diversity using the proposed scheme.