• 한국가구학회지
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• 제20권6호
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• pp.599-604
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• 2009

For the search of unified law of moisture movement in wood, moisture distribution of Korean red pine at non-steady state was investigated. We assume that the equilibrium moisture content (EMC) in wood depends on only temperature and relative humidity, it can be control in temperature and humidity chamber. If temperature is constant and humidity or vapor pressure is changed with sin curve shape at adequate cycles, EMC in chamber can be changed as well with sin-curve shape. The setup condition of a non-steady state in humidity control chambers is a constant temperature at $20^{\circ}C$ and 15+10 sin ${\omega}t$ percent EMC. It can be found that the distribution of moisture in the specimen with varying relative humidity are illustrated various types. Moisture in wood is complicated and vibrates with the moisture sorption process. Considering a unified law of moisture movement in wood, it is considered that the most important fact is to search the method of precise diffusion & transfer coefficients.

• 융복합기술연구소 논문집
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• 제7권1호
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• pp.19-22
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• 2017

SI process is one of the most advanced thermochemical water splitting cycles enabling mass production of hydrogen without emitting carbon dioxide when coupled to nuclear heat energy. The highest temperature (close to $1000^{\circ}C$) required in SI process is well matched with the outlet temperature of a coolant circulating a high-temperature gas-cooled reactor at around $950^{\circ}C$. In Section 3, some heat exchangers are included to recover heats from process flows at high temperature. In this work, we designed a heat exchanger based on the $1Nm^3/hr$ $H_2$ production capacity using commercial tools for chemical process design.

• Journal of Advanced Marine Engineering and Technology
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• 제6권2호
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• pp.51-68
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• 1982

A method of calculation of temperature distribution during welding was studied and compared with the existing formulas and experimental results. In contrast to the existing formulas which are founded on the suppositions that the heat source is a point and that the dimensions of welded pieces are infinite, we tried to make the distribution of calorific density of heat source approach reality more closely, so we considered it as a normal distribution of Gauss, and we presented the formulas for calculation of temperature during welding. We also used the principle of superposition for the temperature calculations of finite welded pieces. We compared the formulas presented in this paper with the existing formulas by calculations for the welding of various materials, and considerable differences around the heat source were convinced. The thermal cycles of various points were traced through the welding experiments for the mild steel, and they were compared with the results of calculations.

• International Journal of Aeronautical and Space Sciences
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• 제12권4호
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• pp.379-384
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• 2011

This paper performs numerical prediction of fuel temperature in the fuel tanks of unmanned air vehicles for both ground static non-operating and in flight transient conditions. The calculation is carried out using a modified Dufort-Frankel scheme. For this calculation, it is assumed that a non-operating vehicle on the ground is subjected to repeating daily cycles of ambient temperature with solar radiation and wind under 1%, with a 20% probability of hot day conditions. The energy conservation equation is used as the governing equation to calculate heat transfer between the fuel tank surface and the ambient environment. Results of the present analysis may be used as the estimated initial values of fuel temperatures in a vehicle's fuel tank for the purpose of analyzing transient fuel temperatures during various flight missions. This research also demonstrates that the fuel temperature of the front tank is higher than that of the rear tank, and that the difference between the two temperatures increases in the later phases of flight due to the consumption of fuel.

• 설비공학논문집
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• 제13권10호
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• pp.923-929
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• 2001

The objectives of this paper are to develop an advanced GAX cycle named HGAX (Hybrid Generator Absorber heat eXchange) cycle, and to study the effect of key pa-rameters on the cycle performance and the evaporating temperature. Two different HGAX cycles are developed-Type A (Performance improvement) and Type B (Low temperature applications). A compressor is placed between the evaporator and the absorber, and the evaporator pressure and the absorber pressure are controlled according to its application purpose. It was found that the COP could be improved by 24% compared with the conventional GAX cycle and the evaporating temperature as low as -8$0^{\circ}C$ could be obtained from the HGAX cycle.

• 한국진공학회지
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• 제5권4호
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• pp.365-370
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• 1996

전기적 착색 텅스텐 산화물박막의 전자비임 증착으로 제작하였으며 제작된 막의 화학적 안정성의 기판온도 의존성을 연구하였다. 실험결과로부터, 제작된 시료의 광학적 특성과 화학적 안정성은 강하게 기판온도에 의존하였다. 기판온도 $80^{\circ}C$에서 제작된 $WO_3$막은 유기성 용액 0.6몰 $LiClO_4$속에서 착색과 탈색이 반복되어도 가장 안정하였다.

• 한국안전학회지
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• 제4권1호
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• pp.25-39
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• 1989

Cyclic temperature creep tests were carried out an AS 7075 alloy specimens were subjected to a constant load and stepwise temperature cycles in which temperature was fluctuated between 30$0^{\circ}C$ and 25$0^{\circ}C$ with three different cycle ratios. The highest frequency of cycling was 1 cycle per 10 hr and the lowest one was 1 cycle per 12 hr. From the creep experimental results with the above conditions the creep strain under cyclic temperature can be predicted easily by introd ucing the equivalent steady temperature because defined by Eq.(16), but the rupture life is 1.1 time than those of constant temperature because of effect of temperature history at tertiary creep range. Besides thlis result, the results of the creep test under cyclic temperature conditions are respectively compayiea with calculated rupture lives using the life fraction law and Eq.(18). The agreement between the obseried rupture times and calculated ones is fairly good. So creep rupture lives can be respectively predicted using life fraction law and Eq.(18).

• Nuclear Engineering and Technology
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• 제53권7호
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• pp.2407-2417
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• 2021

A structural integrity evaluation program (STEP) was developed for the high temperature reactor design evaluation according to the ASME Boiler and Pressure Vessel Code (ASME B&PV), Section III, Rules for Construction of Nuclear Facility Components, Division 5, High Temperature Reactors, Subsection HB. The program computerized HBB-3200 (the design by analysis procedures for primary stress intensities in high temperature services) and Appendix T (HBB-T) (the evaluation procedures for strain, creep and fatigue in high temperature services). For evaluation, the material properties and isochronous curves presented in Section II, Part D and HBB-T were computerized for the candidate materials for high temperature reactors. The program computerized the evaluation procedures and the constants for the weldment. The program can generate stress/temperature time histories of various loads and superimpose them for creep damage evaluation. The program increases the efficiency of high temperature reactor design and eliminates human errors due to hand calculations. Comparisons that verified the evaluation results that used the STEP and the direct calculations that used the Excel confirmed that the STEP can perform complex evaluations in an efficient and reliable way. In particular, fatigue and creep damage assessment results are provided to validate the operating conditions with multiple types of cycles.

• Coupled systems mechanics
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• 제8권3호
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• pp.273-287
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• 2019

Elastoplastic analysis of an annular disc, being fully constrained on its outer rim and interacting with a purely elastic inclusion perfectly bonded with its inner rim, is conducted to study its plastic deformation and residual stress under thermal cycles. The system is termed the composite disc. Quasi-static plane-strain deformation is assumed, and the von Mises yield criterion with or without the Ludwik hardening rule is adopted in our finite element calculations. Effects of multiple material properties simultaneously being temperature dependent on the plastic behavior of the composite disc are considered. Residual stress is analyzed from a complete loading and unloading cycle. Results are discussed for various inclusion radii. It is found that when temperature dependent material properties are considered, the maximum residual stress may be greater than the maximum stress inside the disc at the temperature-loaded state due to lower temperature having larger yield stress. Temperature independent material properties overestimate stresses inside materials, as well as the elastic irreversible temperature and plastic collapse temperature.

• 한국식품조리과학회지
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• 제11권3호
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• pp.261-266
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• 1995

3 종류의 생선(광어, 새우, 굴) homogenate와 tryptic soy broth(TSB)에 Staphylococcus aureus와 Listeria monocytogenes를 접종하여 35$^{\circ}C$에서의 증식과 냉장(5$^{\circ}C$) 및 동결저장(-2$0^{\circ}C$) 하였을 때 각 세균의 거동을 조사하였다. S. aureus는 생선 homogenate와 액체배지 모두 35$^{\circ}C$에서 큰 차이없이 빠르게 증식하였다. 5$^{\circ}C$에 3주간 저장하였을 때 S. aureus는 1-1.6 log cycle 감소하였으나 -2$0^{\circ}C$에서는 6주간의 저장기간 동안 0.3-1.2 log cycle의 세균수 감소를 나타내었다. L. monocytogenes는 35$^{\circ}C$에서 광어 homogenate, 새우 homogenate와 TSB에서 증식이 빨랐으나 굴 homogenate에서는 유도기를 거친 후에 증식이 진행되었다. 5$^{\circ}C$에서 L. monocytogenes는 광어 homogenate, 새우 homogenate와 TSB에서 3주간 증식이 진행되어 세균수가 3.8-5 log cycle 증가하였으나 굴 homogenate에서는 2.2 log cycle의 증가에 불과하였다. -2$0^{\circ}C$에 6주간 저장하였을 때 L. monocytogenes의 세균수는 광어 homogenate, 새우 homogenate 및 TSB에서 1.5-1.8 log cycle 감소하였으나 굴 homogenate에서는 2.8 log cycle 감소하였다