• EDISON SW 활용 경진대회 논문집
• /
• 제3회(2014년)
• /
• pp.495-497
• /
• 2014

Combining the quantum transport theory with new field of Spin Caloritronics, we investigate on the influence of thermal gradient on the magneto tunnel junction structure under various circumstances. The results indicate enhancement in performance of spintronic device is possible using thermal energy.

• 한국레이저가공학회지
• /
• 제6권1호
• /
• pp.17-24
• /
• 2003

The purpose of this study is to evaluate thermal shock resistance and thermal shock fracture toughness for ATJ graphite. Thermal shock resistance and thermal shock fracture toughness of ATJ graphite are evaluated by using CO$_2$ laser irradiation technique. The laser heat source is irradiated at the center of specimens. Temperature distribution on the specimen surface is measured using the thermocouples of type K and C. SEM and radiographic images are used to observe the cracks which are formed at the thermal shock specimens.

• 대한기계학회논문집
• /
• 제14권1호
• /
• pp.119-129
• /
• 1990

본 연구에서는 선적분화 된 체적력항을 갖는 경계요소법을 이용하여, Griffi- th균열에 대한 열응력세기계수를 구하여 Sumi의 결과와 비교 검토하고, 유무한체내의 대칭 입술형및 대칭 익형 커스프균열들(symmetric lip and airfoil cusp cracks)의 열 응력세기계수를 균열묘면이 단열된 경우와 일정 온도로 유지된 경우에 대해 계산하고 자 한다.

• 대한기계학회논문집
• /
• 제17권7호
• /
• pp.1794-1804
• /
• 1993

The thermal stress intensity factors for interface cracks of Griffith and symmetric lip cusp types under vertical uniform heat flow in a finite body are calculated by boundary element method. The boundary conditions on the crack surfaces are insulated or fixed to constant temperature. The relationship between the stress intensity factors and the displacements on the nodal point of a crack tip element is derived. The numerical values of the thermal stress intensity factors for interface Griffith crack in an infinite body and for symmetric lip cusp crack in a finite and homogeneous body are compared with the previous solutions. The thermal stress intensity factors for symmetric lip cusp interface crack in a finite body are calculated with respect to various effective crack lengths, configuration parameters, material property ratios and the thermal boundary conditions on the crack surfaces. Under the same outer boundary conditions, there are no appreciable differences in the distribution of thermal stress intensity factors with respect to each material properties. But the effect of crack surface thermal boundary conditions on the thermal stress intensity factors is considerable.

• 한국유체기계학회 논문집
• /
• 제10권5호
• /
• pp.20-26
• /
• 2007

Some gate valves are susceptible to pressure locking and thermal binding which prevent the safety function. The safety related gate valves susceptible to pressure locking and thermal binding shall be identified and taken preventive actions to ensure the safety function. The identification of the gate valves susceptible to pressure locking and thermal binding needs the evaluation of system design, valve and piping arrangement, test requirements, and operating conditions. Application of preventive methods should consider the system safety function, applicability, effectiveness, interface with system design, and cost. The selection procedure of valves susceptible to pressure locking and thermal binding can be effectively used in industry including nuclear power plants. In order to prevent the pressure locking, the hole can be drilled through the one disc of upstream side or down stream and the external equalizing line can be installed from bonnet to downstream or upstream. The double disc parallel seat valve type can be used instead of flexible wedge gate valve to prevent the thermal binding. The identification of gate valves susceptible to pressure locking and thermal binding, and preventive actions will meet the regulatory requirements and enhance the availability and safety of plants.

• Journal of Ceramic Processing Research
• /
• 제13권spc2호
• /
• pp.308-311
• /
• 2012

A wide range of possible hazards existing in thermal batteries are mainly caused by thermal runaway, which results in overheating or explosion in extreme case. Battery separators ensure the separation between two electrodes and the retention of ion-conductive electrolytes. Thermal runaways in thermal batteries can be significantly reduced by the adoption of these separators. The high operating temperature and the violent reactivity in thermal batteries, however, have limited the introduction of conventional separators. As a substitute for separators, MgO powders have been mostly used as a binder to hold molten salt electrolyte. During recent decades the fabrication technology of ceramic fiber, which has excellent mechanical strength and chemical stability, has undergone significant improvement. In this study we adopted wet-laid nonwoven paper making method instead of the electrospinning method which is costly and troublesome to produce in volume. Polymeric precursor can readily be coated on the surface of wet-laid ceramic paper, and be formed into ceramic film after heat treatment. The mechanical strength and the thermo-chemical stability as well as the wetting behaviors of ceramic separators with various molten salts were investigated to be applicable to thermal batteries. Due to their excellent chemical, mechanical, and electrical properties, wet-laid nonwoven separators made from ceramic fibers have revealed positive possibility as new separators for thermal batteries which operate at high temperature with no conspicuous sign of a short circuit and corrosion.

• 천문학회지
• /
• 제29권spc1호
• /
• pp.231-232
• /
• 1996

The local instabilities of accretion disks were extensively studied, with the considerations of radial advection, thermal diffusion and different disk geometry, dominated pressure and optical depth. Two inertial-acoustic modes in a geometrically thin, radiative cooling dominated disk depart from each other if very little advection is included. A geometrically slim, advection-dominated disk is found to be always stable if it is optically thin. However, if it is optically thick, the thermal diffusion has no effect on the stable viscous mode but has a significant contribution to enhance the thermal instability.

• 한국안전학회지
• /
• 제8권4호
• /
• pp.139-148
• /
• 1993

Thermosyphons are simple devices that can passively transport thermal energy over relatively long distance with little temperature degradation. These attributes permit the use of low grade thermal energy for thermal control of structures including the snow melting and deicing to the pavement surface. The thermosyphon system requires no costly energy input and Is completely maintenance free. This paper presents the experimental results of the snow melting system in which thermosyphon was utilized to transfer the geothermal energy to the pavement to obviate slipping traffic accidents due to freezing of pavement in winter.

• 한국자동차공학회논문집
• /
• 제15권6호
• /
• pp.159-164
• /
• 2007

The purpose of this study is to reduce harmful emission gases in the range of stable combustion without loss of a thermal efficiency. Therefore, effects of both exhaust gas recirculation(EGR) and synthetic gas addition on engine performance and emission were investigated in a gasoline engine. Synthetic gas(syngas), which is in general prepared from reforming gasoline, was utilized in order to promote stable combustion. The major components of syngas are H2, CO and $N_2$ gases. The percentage of syngas addition was changed from 0 to 30% in energy fraction and EGR rate was varied up to 30%. As a result, $COV_{IMEP}$ as a parameter of combustion stability was decreased and THC/$NO_X$ emissions were reduced with the increase of syngas addition. And $COV_{IMEP}$ was increased with the increase of EGR but $NO_X$ emission was greatly reduced. In addition, under the region where the EGR rate is around 20%, thermal efficiency was improved.

• 한국지역사회생활과학회지
• /
• 제26권3호
• /
• pp.589-595
• /
• 2015

This study examines how exercise habits affect human thermoregulatory responses. A total of 14 healthy male college students participated in this study as subjects: 8 students who exercised regularly (REG) and 6 students who did not (IREG). First, there were no significant differences between REG and IREG in rectal and mean skin temperatures. Second, the general thermal sensation was "slightly warm" at the equilibrium state and "cool" during body cooling in both groups with no significant differences between the two groups. This implies that exercise habits did not affect the subjective thermal sensation under this study's environmental conditions. Third, there were no significant correlations between the preferred temperature and related variables such as rectal and mean skin temperature changes, oxygen uptake, and the general thermal sensation in REG. However, there were significant correlations between the preferred temperature and the mean skin temperature change (p<0.05) and oxygen uptake(p<0.01) in IREG. In sum, these results suggest weak effects of exercise habits on daily life at the individual level. Therefore, future research should verify this study's results under controlled conditions such as cooling intensity and durations.