• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.2
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• pp.105-114
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• 2016

When impact load is applied to a plate structure, a common phenomenon that occurs in structures is plastic deformation accompanied by a large strain and eventually it will experience a fracture accordingly. In this study, for the rational design against accidental limit state, the plastic material constants of steel plate which is formed by line heating and by cold bending procedure have been defined through the numerical simulation for the high speed tension test. The usefulness of the material constants included in Cowper-Symonds model and Johnson-Cook model with the assumption that strain rate can be neglected when strain rate is less than the intermediate speed is verified through comparing the present numerical results with those in references. This paper ends with describing the future study.

• Journal of the Korean Home Economics Association
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• v.37 no.10
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• pp.81-90
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• 1999

This study investigated the present traditional Korean farmhouse based on a survey of 30 households from Oiam-Ri folk Village in Chung-Nam Province. This study was primarily concerned with the present housing; the size and plan of the house, lighting and heating, the finishing materials of anbang(the master's bedroom or ondol) and the kinds of fumiture. I was also interested in identifying the socio-demographic and physical variables that influenced the housing, both the ordinary farm households and the descendent of nobility households. Bibliographical studies, cultural approaches, field surveys with tape recordings, and questionnaires were used to collect the data. The results showed that the types of house plans were mixed from the southern region(one-line type) and middle region(courtyard type). The heating system and the fuel for the ondol anbang has changed entirely from wood burning system to oil boiler system. The finishing material of the anbang floor changed from traditional oil paper and straw mats to vinyl flooring. Traditional fumiture and small decor items are disappearing and are being replaced by modem items, but the descendents of the nobility household kept many traditional type of fumiture and small decor items.

• Ceramist
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• v.10 no.3
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• pp.67-74
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• 2007

Crystallisation kinetics of the erbium doped soda-tellurite glasses were studied using the differential thermal analysis (DTA) and differential scanning calorimetery (DSC) techniques. The DTA curves in the temperature range of 350 K to 650 K were obtained from isochronal heating rates, chosen in the range of 2 to 20 K/min. DSC isothermal curves were used to calculate the fraction of crystals formed on reheating. The apparent activation energies for devitrification were derived by measuring the shifts in the values of $T_g$ and $T_x$ with heating rates, using the Kissinger method. The derived values of apparent activation energies for isochronal and isothermal methods varied in the range of $190-204\;{\pm}\;5\;kJ\;mol^{-1}$. The X-ray powder diffraction analysis of heat treated and transparent samples showed the presence of nano-scale size sodium-tellurite crystals. These crystallites were found to have a strong influence on the full width of half maxima of the transition in $Er^{3+}:\;^4I_{13/2}{\rightarrow}^4I_{15/2}$, which extended from 70 nm in the vitreous materials to 132 nm in glass-ceramic materials.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.188-192
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• 2006

This study is conducted to improve efficiency of thermal storage tank. The thermal storage tank was designed to store heat energy that obtained from solar or the others heat sources. However, it has difficulties in storing heat with uniform temperature through the entire tank with respect to vertical direction. This kind of maldistribution of the supplied heat to the storage tank effects on the system performance. In this study is focused on utilization of the thermal stratification to improve thermal comfort for people in the house. To enhance temperature stratification of the tank, a distributor was designed and Installed in the middle of the tank. The distributor is supplies hottest water to the top side of the tank which is very close to inlet of the supply line to the heating load. The hottest water that is accumulated on top side of the tank is firstly supplied to the load with higher temperature. Reminder water takes a little time to warming up until desired supply temperature reached. This kind alternating selection of the supply temperature is improve thermal comfort with moderated system performance.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.570-578
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• 2008

A flexible forming apparatus is composed a number of punches which have spherical pin tip shape instead of conventional solid die. The flexible forming tool consisted of punch array in a matrix form was proposed as an alternative forming method to substitute the conventional line heating method which use heat source to induce residual stress along specified heating lines. In this study, application of the flexible forming process to the small scale curved plate forming was conducted. Numerical simulations for both solid and flexible die forming process were carried out to compare the shape of the products between flexible and conventional die forming process. In addition, spring-back analysis was conducted to figure out the feasibility of the flexible forming process comparing with the die forming process in view of final configuration of the specimens. Moreover, experiment was also carried out to confirm the formability of the process. Consequently, it was confirmed that the flexible die forming method has capability and feasibility to manufacture the curved plates for shipbuilding.

• Magazine of the Korean Society of Agricultural Engineers
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• v.16 no.2
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• pp.3395-3409
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• 1974

The purpose of this study is to test and compare the efficiency of heating-system for materials and construction of the wall, ceiling and window in soil brick house, cement house and boulder house respectively, in order to construct ideal farm houses in rural area. The results obtained were as follows: 1. In heat conservation due to construction of walls the thermal efficiency of cement brick house was equivalent to 66.3% of that of soil brick house, and boulder house 60.3% 2. In the case of ceiling, the thermal efficiency of paper ceiling was amounted to 84.2% of that of the composite ceiling (thickness 6mm veneer+thickness. l0m chaffs), and the common ceiling putting on soil above the ceiling, 76% of the composite while the efficiency of the ceiling putting on chaffs above them was 15.8% higher than that of the paper. 3. In the case of improving the window, the double type was 12% higher than. the efficiency of single type. 4. The warming velocity of conventional house was slower but the velocity of radiation was quicker than that of experimental one. It was thought to be due to unscietific constructions of the room bottom, fire inlet and chimney, 5. The temperature gradient line was not dependad upon the amount of throwing into fuel in the rural farm house. 6. It was concluded that the final thermal efficiency of the conventional farm house was 10.6% lower than that of experimental farm house.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.88.1-88.1
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• 2011

Shocks are thought to be important in the dynamics and heating of the solar chromosphere. The observational determination of shock parameters, however, has been hardly done because of the difficulty of observation at a high spatial, temporal and spectral resolution, and the lack of an effective method of inferring physical parameters from spectral data. Our inversion of the spectral data of the $H{\alpha}$ and Ca II 854.2 nm lines simultaneously taken from an intranetwork area, produced temporal profiles of temperature as well as line-of-sight velocities, from which we infer that three-minute chromospheric oscillations prevailing in the upper chromosphere are in fact trains of strong shocks with a strength of about two and a propagation speed of 20 km s-1 that carry a mechanical energy flux of 500 W m-2 upward. Our result supports the notion that shocks dominate the heating of the upper chromosphere, and probably the corona as well, at least in intranetwork regions of the quiet sun.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.1
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• pp.70-76
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• 2015

The ship hull is accomplished by assembling various curved surfaces. There are numerous existing methods for ship hull processing, which need certain appropriate processing methods to enable it to be more efficient. The curved hull plates can be divided into convex region and saddle region. It is common to use line heating method to form a saddle region, when it comes to a convex region, it will be triangle heating method to be utilized. A precise analysis for curvature domain is required for the application of proper processing method. There exist various problems on existing calculation methods of curvature domain. Therefore, a more powerful method is demanded to it more accurately. In this study, a method called Dual Contouring is applied to extract curved surfaces, which is able to improve accuracy of extracted area. Based on all above, a best-suited heat processing method should be selected.

• Journal of the Korean Solar Energy Society
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• v.33 no.1
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• pp.96-105
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• 2013

This study aims to investigate the energy performance of apartment in respect of complex design, building type and generation house layout and finally to produce the guide line for energy saving design. To grasp the present condition and problem about this subject, apartment building types were examined and representative types were extracted. Considering azimuth angle, private area, and generation number, building type of the subject apartment was classified in detail, energy simulation was conducted, and the effect to energy cost was compared. In the research, using VE energy simulation program, the heating and cooling load were calculated and converted to energy cost. It is expected that this analysed results will be basic data for the more integrated study. Research consequence can be summarized as follow: 1) Energy cost is compared according to several azimuth in plank '一' type apartment. As the results, calculated gas cost is the best in $49^{\circ}$, but total cost is in $-31^{\circ}$. 2) Apartment buildings of tower types are compared, it is resulted that 'Y' type (azimuth $-7^{\circ}$, $-20^{\circ}$) is the best in gas cost, but the total cost is worst because of high cooling load.

• Journal of Environmental Science International
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• v.29 no.11
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• pp.1141-1151
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• 2020

The impact of sound speed variability in the sea is the very important on acoustic propagation for the underwater acoustic systems. Understanding of the temporal and spatial variability of ocean sound speed in the sea around the Ieodo were obtained using oceanographic data (temperature, salinity). from the Korea Oceanographic Data Center, collected by season for 17 years. The vertical distributions of sound speed are mainly related to seasonal variations and various current such as Chinese coastal water, Yellow Sea Cold Water (YSCW), Kuroshio source water. The standard deviations show that great variations of sound speed exist in the upper layer and observation station between 16 and 18. In order to quantitatively explain the reason for sound speed variations, Empirical Orthogonal Function (EOF) analysis was performed on sound speed data at the Line 316 covering 68 cruises between 2002 and 2018. Three main modes of EOFs respectively revealed 55, 29, and 5% the total variance of sound speed. The first mode of the EOFs was associated with influence of surface heating. The second EOFs pattern shows that contributions of YSCW and surface heating. The first and second modes had seasonal and inter-annul variations.