• Steel and Composite Structures
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• v.14 no.3
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• pp.205-227
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• 2013

Current design standards do not provide adequate guidelines for the fire design of cold-formed steel compression members subject to flexural-torsional buckling. Eurocode 3 Part 1.2 (2005) recommends the same fire design guidelines for both hot-rolled and cold-formed steel compression members subject to flexural-torsional buckling although considerable behavioural differences exist between cold-formed and hot-rolled steel members. Past research has recommended the use of ambient temperature cold-formed steel design rules for the fire design of cold-formed steel compression members provided appropriately reduced mechanical properties are used at elevated temperatures. To assess the accuracy of flexural-torsional buckling design rules in both ambient temperature cold-formed steel design and fire design standards, an experimental study of slender cold-formed steel compression members was undertaken at both ambient and elevated temperatures. This paper presents the details of this experimental study, its results, and their comparison with the predictions from the current design rules. It was found that the current ambient temperature design rules are conservative while the fire design rules are overly conservative. Suitable recommendations have been made in relation to the currently available design rules for flexural-torsional buckling including methods of improvement. Most importantly, this paper has addressed the lack of experimental results for slender cold-formed steel columns at elevated temperatures.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2061-2078
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• 2006

The main purpose of this paper is to establish the high temperature structural integrity evaluating procedures for the next generation reactors, which are to be operated at over 500$^{\circ}C$ and for 60 years. To do this, comparison studies of the high temperature structural design codes and assessment procedures such as the ASME-NH (USA), RCC-MR (France), DDS (Japan), and R5 (UK) are carried out in view of the accumulated inelastic strain and the creep-fatigue damage evaluations. Also the application procedures of the ASME-NH rules with the actual thermal and structural analysis results are described in detail. To overcome the complexity and the engineering costs arising from a real application of the ASME-NH rules by hand, all the procedures established in this study such as the time-dependent primary stress limits, total accumulated creep ratcheting strain limits, and the creep-fatigue damage limits are computerized and implemented into the SIE ASME-NH program. Using this program, the selected high temperature structures subjected to two cycle types are evaluated and the parametric studies for the effects of the time step size, primary load, number of cycles, normal temperature for the creep damage evaluations and the effects of the load history on the creep ratcheting strain calculations are investigated.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.331-332
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• 2012

Structural steel has been used as a primary materials to columns and beams since 1960's in Korea with an advantages of excellent of load-bearing capacity and design flexibility, and faster construction. However, if the steel columns made of structural steel exposed to fire the load-bearing capacity is going down steadily and finally reach to collapse. Therefore, building regulation requires fire resistance according to building occupation, scales. The fire resistance can be evaluated two categories. One is prescriptive method that is based on building regulation, specification and so on and the other is performance-based fire engineering method. The latter can be designed based on scientific and engineering consequences. The easiest evaluation way using the fire engineering design is comparing to the limiting temperature and maximum temperature calculated based on heat transfer theory. If the limiting temperature of a column exceeds the maximum temperature of it, the column can carry the load during the fire. Therefore, the database of limiting temperature is very essential for evaluation of column. In this paper, to build the database of column made of rectangular hollow sections 8 fire tests with loading were conducted and the relation between the limiting temperature and the applied loads showed in reverse proportion.

• Journal of Korean Society on Water Environment
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• v.26 no.1
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• pp.140-147
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• 2010

In existing design method for aeration tank water temperature was considered as governing variable for applying safety factor. This study tried a few new approach of aeration tank design using SOUR at various temperature conditions. Specific substrate utilization rate (U) and specific oxygen uptake rate (SOUR) both were analyzed at various temperature and SRT. The laboratory scale reactor was operated on various temperature ($10^{\circ}C$, $20^{\circ}C$, $25^{\circ}C$) and SRT (5day, 10day, 20day, 30day). In this study, SOUR tended to increase with the temperature increased. On the other hand, SOUR tended to decrease when SRT increased from 5 days to 30 days. Empirical equations were obtained SOUR=a/SRT+b and $SOUR=(a/m){\cdot}U+(b-a(n/m))$ from the relationship between SRT, U and SOUR. Empirical equations shows the possibility as a new design method for the aeration basin.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.323-327
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• 2020

In this study, the neutronic calculation to obtain tritium breeding ratio (TBR) in a deuterium-tritium (D-T) fusion power reactor using Monte Carlo MCNPX is done. In addition, by using COMSOL software, an efficient cooling system is designed. In the proposed design, it is adequate to enrich up to 40% ⁶Li. Total tritium breeding ratio of 1.12 is achieved. The temperature of helium as coolant gas never exceed 687℃. As regards the tolerable temperature of beryllium (650℃), the design of blanket module is done in the way that beryllium temperature never exceed 600℃. The main feature of this design indicates the temperature of helium coolant is higher than other proposed models for blanket module, therefore power of electricity generation will increase.

• Transactions of Materials Processing
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• v.14 no.3 s.75
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• pp.263-268
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• 2005

Heating channel layout design and evaluation technology for SMC molding system was investigated in this work. Traditional rules of cooling channel design in injection molding were applied to the present work. Finite element thermal analysis with $ANSYS^{TM}$ was performed to evaluate the temperature distribution of SHC mold surface. SMC mold was manufactured to evaluate the effect of a proposed heating channel layout system on the temperature distribution of SMC mold surface and infrared camera was applied to a measurement of temperature distribution. It was shown that infrared camera application was possible in a measurement of temperature distribution on SHC mold surface.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1061-1064
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• 2006

Optimal design of functionally graded plates is investigated considering stress and critical temperature. Material properties are assumed to be temperature dependent and varied continuously in the thickness direction. The effective material properties are obtained by applying linear rule of mixtures. The 3-D finite element model is adopted using an 18-node solid element to analyze more accurately the variation of material properties and temperature field in the thickness direction. For stress analysis, the tensile stress ratio and compressive stress ratio of the structure under mechanical load are investigated. In the thermo-mechanical buckling analysis, temperature at each node is obtained by solving the steady-state heat transfer problem and Newton-Raphson method is used for material nonlinear analysis. Finally, the optimal design of FGM plates is studied for stress reduction and improving thermo-mechanical buckling behavior, simultaneously.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.10
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• pp.1294-1299
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• 2000

The combustion characteristics have been investigated to develop the 50 kW-class gas turbine combustor. The combustor design program was developed and applied to design this combustor. The combustion air which has the temperature of 45, 200, $300^{\circ}C$ were supplied to combustor for elucidating the effect of inlet air temperature on CO, NOx emissions and flame temperature. The exit temperature and NO were increased and CO was decreased with increasing inlet air temperature. Also, the effect of equivalence ratio was considered to verify the combustor performance. The emissions of CO and NO with inlet air temperature can be analyzed qualitatively by measuring the temperature inside the combustor. The combustion performance with fuel schedule was evaluated to get the informations of the starting and part loading process of gas turbine. The combustion was stable above the equivalence ratio of 0.18. The pattern factor which is the important parameter of combustor performance was satisfied with the design criterion. Consequently the combustor was proved to meet the performance goal required for the target gas turbine system.

• The International Journal of Costume Culture
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• v.3 no.1
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• pp.30-40
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• 2000

The purpose of this research was to device thermal comfort model for radiation power plant workers in protective clothing. Three fabrics commonly used in protective workwear were made into coveralls of identical design and were evaluated by adult healthy males in four simulated work environment. It was investigated between the physiological response and subjects comfort according to environmental variance and clothing types. The of simulated work enviro mensent was controlled under four different humidity and temperature of each type. (Temperature 20±1℃, RH 40∼70%±5%, Temperature 30±1℃, RH 40∼70%±5%) An index of physiological response was connected with the thermal comfort designed. Mean skin temperature, skim temperature, Axillasy temperature ear canal temperature, clothing climate, total sweat, blood pressure, and R-R interval were be evaluated. Skin temperature difference ocurring during exercise and rest were significant only with respect to time and regions of the body, This despite physical differences in the three coveralls, particulary mass statistically experiment. Also, an index of subject wearing sensation was designed for thermal comfort after investigation determined the kind of clothes and the type of environment. As a result of this research, two types of multiple regressions was deviced to estimate thermal comfort of the protective clothing.

• Nuclear Engineering and Technology
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• v.41 no.10
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• pp.1323-1332
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• 2009

The IHX (Intermediate Heat eXchanger) for a pool-type SFR (Sodium-cooled Fast Reactor) system transfers heat from the primary high temperature sodium to the intermediate cold temperature sodium. The upper structure of the IHX is a coaxial structure designed to form a flow path for both the secondary high temperature and low temperature sodium. The coaxial structure of the IHX consists of a central downcomer and riser for the incoming and outgoing intermediate sodium, respectively. The IHX of a pool-type SFR is supported at the upper surface of the reactor head with an IHX support structure that connects the IHX riser cylinder to the reactor head. The reactor head is generally maintained at the low temperature regime, but the riser cylinder is exposed in the elevated temperature region. The resultant complicated temperature distribution of the co-axial structure including the IHX support structure may induce a severe thermal stress distribution. In this study, the structural feasibility of the current upper support structure concept is investigated through a preliminary stress analysis and an alternative design concept to accommodate the IHTS (Intermediate Heat Transport System) piping expansion loads and severe thermal stress is proposed. Through the structural analysis it is found that the alternative design concept is effective in reducing the thermal stress and acquiring structural integrity.