• Korean Journal of Poultry Science
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• v.13 no.1
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• pp.23-30
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• 1986

The Calorimetric experiment was made firstly to measure the difference in energy metabolisms of laying hens among their three different laying periods, secondly to estimate the energy requirements of the layers on their respective laying periods. The laying period was divided into three chronological periods of 25-40, 41-55, and 56-69 weeks old of laying hens, which are refered to as period I, II, and III respectively. 1) The fasting heat production (FHP) of laying hen on the three laying periods were 81.5 Kcal/kg$\^$0.75/ for period I, 72.3 Kcal/kg$\^$0.75/ for perod II, and 97.5 Kcal/kg$\^$0.75/ for perod III. The marked increase in FHP was found in period m, while there was a small difference in FHP between period I and II. The present study have observed among the birds in period in the high degree of plumage defectiveness, and this condition of bird might have accounted for the increase in FHP. 2) The regression equation between ME intake and energy retention (ER) were calculated, and the equations indicated that, for the period I, II, and III, the ME requirements for maintenance (MEm) were 123, 111, and 131 Kcal/kg$\^$0.75/ respectively, and that the Net Availabilities of Metabolizable energy (NAME) were 76, 79, and 74 percent respectively. For the whole laying period measured, MEm was 119 Kcal/kg$\^$0.75/ and NAME was 79 percent. There was a tendancy of higher MEm, and lower NAME during Period III, comparing with period I and II.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.4
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• pp.355-364
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• 2016

Recently, a 3,250 meter-long tunnel was constructed beneath the sea bed formed of composite sedimentary soils to transport reusable waste heat gas of industrial complex in the west coast of Korea. Some risks such as machine settlement always exist due to the uncertainties of geological and construction factors during the subsea shield TBM tunnelling. In this construction site, the deviation of tunnel alignment caused by shield TBM settlement was occurred during excavation. It was examined that the lack of bearing capacity of soft clay was a main cause. This paper evaluates the risk of shield TBM tunnelling considering the ground conditions. Correlation between machine settlement and its advance rate was evaluated through the analytical equation in which bearing capacity is considered and a 3-D numerical analysis which can simulate the TBM advance condition (in other words, the dynamic condition). It was found out that a shield TBM could settle due to the insufficient bearing capacity of soft clay layers. In order to prevent such the problem, the best advance rate proper to the ground characteristics is needed to be applied. In the ground conditions of the section of interest, it was turned out that if the shield TBM advance rate was maintained between 35 mm/min and 40 mm/min, the machine settlement could be avoided.

• Nuclear Engineering and Technology
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• v.52 no.4
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• pp.721-733
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• 2020

In nuclear engineering, the occurrence of critical heat flux (CHF) is complicated for rod bundle, and it is much more difficult to predict the CHF when it is in natural circulation under motion condition. In this paper, the dryout-type CHF is investigated for the rod bundle in a natural circulation loop under rolling motion condition based on the coupled analysis of subchannel method, a one-dimensional system analysis method and a CHF mechanism model, namely the three-fluid model for annular flow. In order to consider the rolling effect of the natural circulation loop, the subchannel model is connected to the one-dimensional system code at the inlet and outlet of the rod bundle. The subchannel analysis provides the local thermal hydraulic parameters as input for the CHF mechanism model to calculate the occurrence of CHF. The rolling motion is modeled by additional motion forces in the momentum equation. First, the calculation methods of the natural circulation and CHF are validated by a published natural circulation experiment data and a CHF empirical correlation, respectively. Then, the CHF of the rod bundle in a natural circulation loop under both the stationary and rolling motion condition is predicted and analyzed. According to the calculation results, CHF under stationary condition is smaller than that under rolling motion condition. Besides, the CHF decreases with the increase of the rolling period and angular acceleration amplitude within the range of inlet subcooling and mass flux adopted in the current research. This paper can provide useful information for the prediction of CHF in natural circulation under motion condition, which is important for the nuclear reactor design improvement and safety analysis.

• Journal of the Korean earth science society
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• v.32 no.6
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• pp.629-639
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• 2011

Based on Maxwell-Eucken(ME) model, which is one of structural models, a new model for predicting the effective thermal conductivity of variably saturated porous materials is proposed. The new model is a linear combination of three ME models having matrix, water, and air as a continuous phase. The coefficient of the corresponding linear equation is defined by a parameter referred to as 'the continuity coefficient', which provides a relative degree of continuity of each phase. The continuity coefficient of matrix is assumed to be linearly proportional to porosity. The model can be linear or nonlinear depending on how the continuity coefficients of water and air vary with water saturation. The feasibility of the proposed model was examined by both numerical and experimental results. Both linear and nonlinear models showed a high accuracy of prediction with $R^2$ values of 0.86-0.98 and 0.88-0.99, respectively. The numerical and experimental results also showed that the continuity coefficient of matrix was linearly proportional to porosity. Therefore, the proposed prediction model can be effectively used to estimate effective thermal conductivity of unsaturated porous materials by measuring porosity, water content and mineralogical compositions of matrix.

• Fire Science and Engineering
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• v.25 no.4
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• pp.103-109
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• 2011

In this study, we calculated the smoke movement at the fire area of the refuge floor which has the refuge safety area in case of fire in the high rise building by using a computational fluid dynamics (CFD) code of FLUENT (ver. 13.0). The buoyancy plume was applied using the temperature and flow velocity which represent 10 MW heat release rate in order to describe the fire, and the smoke movement was predicted using a species conservation equation. The pressurization system of smoke control was adopted with smoke control damper in refuge safety area, at the result, it is confirmed that the damper capacity was enough to smoke control in which the flow rate of supply was applied 25 $m^3/s$ in the case of the door at fire area opened only, and 50 $m^3/s$ in the doors at the fire area and lobby both opened case. They were satisfied in NFSC 501-A. Even though the door of fire area closed, there were smoke leakages at the gap between the door and wall. In addition, the refugee could be isolated in the fire area when the door of fire area closed during smoke control in the case of using the high damper flow rate of supply, 50 $m^3/s$. Therefore the proper damper flow rate of supply are needed in order to prevent the damage of refugee and this study proposes the suitable condition of damper capacity according to refuge scenario.

• Korean Journal of Food Science and Technology
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• v.22 no.7
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• pp.799-801
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• 1990

Of the several methods proposed for decreasing toxicity of Paralytic shellfish poison(PSP) from intoxicated shellfish, heat treatment has been most popular, although a large percentage of the incidents of PSP illness have been related to the ingestion of cooked shellfish. The purpose of this study was to determine the kinetics of PSP destruction at various temperatures. The homogenate of intoxicated blue mussel(Mytilus edulis) was heated at temperature ranging from $90\;to\;121^{\circ}C$ and toxicities measured in samples heated for various time intervals. The rate constant(k) per second was $3{\times}10^{-4},\;at\;90^{\circ}C,\;4.98{\times}10^{-4},\;at\;100^{\circ}C,\;7.38{\times}10^{-4},\;at\;116^{\circ}C,\;and\;8.38{\times}10^{-4},\;at\;121^{\circ}C,\;$. By the Arrhenius equation, the decimal reduction time(D-value) was $121min.\;at\;90^{\circ}C,\;82min,\;at\;100^{\circ}C,\;58min.\;at\;116^{\circ}C\;and\;53min.\;at\;121^{\circ}C$. The z-value, activation energy($E_a\;and\;Q_{10}$) was $72^{\circ}C,\;3.9{\times}10^7(J/kg\;mol)$ and 1.39, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.189-193
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• 1981

An apparatus for continuous measurements of sorption isotherm of dried food was manufactured to shorten the time required for equilibration. The apparatus was so designed that the temperature, air velocity and relative humidity in the experimental chamber could be controlled. The use of dynamic stream of conditioned air with a velocity of 0.2m/sec, instead of static atmosphere, allowed a faster equilibration of dried filefish muscle at $25^{\circ}C$. The mean time necessary for the equilibration of dried filefish muscle at the water activity of a given state to a higher water activity was about 45 hours. The monolayer moisture content of dried filefish muscle calculated from BET-equation was 0.092 kg water /kg dry matter at $25^{\circ}C$.

• Journal of Adhesion and Interface
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• v.5 no.1
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• pp.3-11
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• 2004

In this work, the cure behaviors of the DGEBA/PMR-15 blends initiated by N-benzylpyrazinium hexafluoroantimonate (BPH) as a cationic latent catalyst were performed in DSC and DMA analyses. And, the thermal stabilities were carried out by TGA analysis and their mechanical interfacial properties of blends were measured in the context of critical stress intensity factor ($K_{IC}$). As a result, the curing activation energy ($E_a$) determined from Ozawa's equation in DSC and the relaxation activation energy ($E_r$) from DMA were increased with increasing PMA-15 content. Also, the thermal stabilities obtained from the integral procedural decomposition temperature (IPDT) and the glass transition temperature ($T_g$) were highly improved with increasing the PMR-15 content, which were probably due to the high heat resistance. And, the $K_{IC}$ showed a similar behavior with $E_a$, which was attributed to the improving of the interfacial adhesion or hydrogen bondings between intermolecular chains.

• Food Science and Preservation
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• v.10 no.2
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• pp.125-130
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• 2003

This study was carried out to investigate the thermo-physical properties and design Freezing time prediction model from data of freezing test of Kimchi. Density of Kimchi were measured as 1001.9 ${\pm}$0.03 kg/㎥ at unfrozen state, 987.0 ${\pm}$0.07 kg/㎥ at frozen state and volume of the Kimchi expanded 4.67% at -l5$^{\circ}C$. Initial freezing point of Kimchi and seasoning were -4.0$^{\circ}C$ and -2.5$^{\circ}C$, respectively. Freezing ratio of Kimchi were estimated more than 50％ at -5.0$^{\circ}C$, more than 75% at -l0$^{\circ}C$ and approximately 90% at -25$^{\circ}C$. To obtain equation for freezing time prediction of Kimchi, freezing time(Y) was regressed against the reciprocal( $X_3$) of difference of initial freezing point and freezing medium temperature, reciprocal( $X_4$) of surface heat transfer coefficient, the initial temperature( $X_1$) and thickness( $X_2$) of samples. As results of the multiple regression analysis, equations were obtained as follows. Y$_{kimchi}$=3.856 $X_1$+13982.8 $X_2$+8305.166 $X_3$+ 3559.181 $X_4$-639.189( $R^2$=0.9632). These equations shown better results than previous models, and the accuracy of its was very high as average absolute difference of about 10% in the difference between the fitted and experimental results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.97-107
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• 2020

In this study, finite element analysis was carried out through the finite element analysis program (ANSYS) to investigate the fire resistance of composite columns in fire. Transient heat transfer analysis and static structural analysis were performed according to ASTM E 119 heating curve and axial force ratio 0.7, 0.6, 0.5 by applying stress-strain curves according to temperature, and loading heating experiments were carried out under the same conditions. In addition, the nominal compressive strength of the composite column according to the heating time according to the standard(Eurocode 4) was calculated and expressed as the axial force ratio and compared with the analytical and experimental values. Through the analysis, As a result of finite element analysis, the fire resistance time was 180 minutes and similar value to the experimental value was obtained, whereas the fire resistance time 150 minutes and 60 minutes were derived from the axial force ratios 0.6 and 0.7. In addition, it was confirmed that the fire resistance time according to the axial force ratio calculated according to the reference equation (Eurocode 4) was lower than the actual experimental value. However, it was confirmed that the standard(Eurocode 4) was higher than the experimental value at the axial force ratio of 0.7. Accordingly, it is possible to confirm the fire resistance characteristics(time-axial force ratio relationship) of the SRC column at high axial force, and to use the experimental and anaylsis data of the SRC column as the data for verification based on Eurocode.