• International Journal of Air-Conditioning and Refrigeration
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• 제10권1호
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• pp.1-9
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• 2002

Effects of temperature coefficients fur dielectric constants on transient reflectances and thermal responses have been investigated for a metal(gold) thin-film during ultrashort pulse laser heating. Heating processes are simulated using the conventional conduction model(parabolic one-step, POS), the parabolic tow-step model(PTS), the hyperbolic two-step model(HTS). Results fro the HTS model are very similar to those from the PTS model, since the laser heating time in this study is considerably greater than the electron relaxation time. PTS and HTS models, however, result in completely different temperature profiles from those obtained by the POS model due to slow electron-lattice interactions compared to laser pulse duration. Transient reflectances are directly estimated from the linear relationship between electron temperature and complex dielectric constants, while conventional approaches assume that the change in reflectances is proportional to that in temperatuer. Reflectances at the front surface vary considerably for various dielectric constants, while those at the rear surface remain unchanged relatively.

• 한국전기전자재료학회논문지
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• 제14권5호
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• pp.405-409
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• 2001

This paper describes fabrication and characteristics of metal thin-film pressure sensor for working at high temperature. The proposed pressure consists of a chrom thin-film, patterned on a Wheat stone bridge configuration, sputter-deposited onto thermally oxidized Si membranes with an aluminium interconnection layer. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.097∼1.21mV/V$.$kgf/$\textrm{cm}^2$ in the temperature range of 25∼200$^{\circ}C$ and the maximum non-linearity is 0.43%FS.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 추계 학술논문 발표대회
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• pp.161-164
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• 2009

This research is to show the mechanical properties of structural steels by welding at high temperature. Welding parts are divided with weld metal and HAZ(Heat Affected Zone). HAZ is formed by interval from welding heat source and heating and cooling rates. Then, the change of both microstructure and mechanical properties occurs. Discontinuity of mechanical and chemical property at HAZ is the cause of safety decrease of structure. At this point, in this research, tensile tests at high temperature with test pieces of base metal and weld metal of SS400 and SM490 are accomplished. From the results, the mechanical properties of both SS400 and SM490 are standardized without welding or non-welding.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.105-106
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• 2007

M-DNAs based on zinc and cobalt ions were formed at the conditions of $26^{\circ}C$, 76% humidity, atmosphere, and pH 8.0. Some process parameters in synthesis of M-DNA such as synthetic temperature, concentration of metal ions, and synthetic time were varied and the electrical properties were investigated by changes of the parameters. The electrical properties of M-DNA showed the dependences on synthetic temperature, concentration of metal ions and synthetic time. The I-V characteristics rapidly increased with each increase of the parameters.

• 한국정밀공학회지
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• 제16권9호
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• pp.117-122
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• 1999

Track rubber parts has heat built-up as long as dynamic loading is applied from running tracked vehicles. Durability is required for rubber part to sustain the heat accumulation and heat exchange between rubber-metal assembly and environmental air and ground. For this research, the track assembly was divided into four parts i.e., bottom track shoe, upper track pad, pin busing and metal structure. Three rubber parts and metal structure were modelled and analyzed with MARC package program to obtain time-temperature data which was induced form mechanical work of tracked vehicles. heat accumulation data was obtained from special experiments under the room temperature of 25$^{\circ}C\;and\;35^{\circ}C$ to simulate the actual environmental conditions. From this research, it is cleared that the environmental temperature does not affect to the heat accumulation speed in rubber parts. Also, the heat built-up mechanism was clarified from the thermo-mechanical work based on numerical analysis and experiments.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 하계학술연구발표회 및 한.일 공동심포지엄
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• pp.17-17
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• 2003

Semiconductors with ferromagnetism at room temperature has been actively searched for in recent years; a prospect of devices using both charge and spin continuously gives impetus to the activities. Transition metal doped oxide materials have been of particular interest. Co substituted ZnO [1] and TiO$_2$ [2] thin films, for example, were reported to show ferromagnetic properties at room temperature. However, various studies do not seem to converge on a definite picture [3,4,5]. The issue is rather fundamental: whether a system shows ferromagnetic properties at all, and in case it does, whether the system possesses a close coupling between magnetism and transport properties. In this talk, we shall assess the current status of transition metal doped oxide materials as room temperature ferromagnetic semiconductors.

• Geomechanics and Engineering
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• 제35권1호
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• pp.81-93
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• 2023

Due to the unclear mechanism of the influence of temperature on the resonance problem of doubly curved shells, this article aims to explore this issue. When the ambient temperature rises, the composite structure will expand. If the thermal effects are considered, the resonance response will become more complex. In the design of structure, thermal effect is inevitable. Therefore, it is of significance to study the resonant behavior of doubly curved shell structures in thermal environment. In view of this, this paper extends the previous work (She and Ding 2023) to the case of the nonlinear principal resonance behavior of graphene platelet reinforced metal foams (GPLRMFs) doubly curved shells in thermal environment. The effect of uniform temperature field is taken into consideration in the constitutive equation, and the nonlinear motion control equation considering temperature effect is derived. The modified Lindstedt Poincare (MLP) method is used to obtain the resonance response of doubly curved shells. Finally, we study the effects of temperature changes, shell types, material parameters, initial geometric imperfection and prestress on the forced vibration behaviors. It can be found that, as the temperature goes up, the resonance position can be advanced.

• 한국산업융합학회 논문집
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• 제27권1호
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• pp.57-62
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• 2024

This study conducted a measurement method of high temeprature conditions using infrared termography. All objects emit infrared light, and this emissivity has a significant impact on the temperature measurements of infrared thermal imaging (IR) cameras. In order to measure the temperature more accurately with the IR camera, correction equations were derived by measuring the emissivity according to the temperature change of combustible metals in a high-temperature environment. Two combustible metals, Mg and Al, were used to measure emissivity with changing temperature. Each metal was heated, the emissivity was measured by comparing the temperature with IR camera and thermocouples so that the correlation between temperature and emissivity could be anslyzed. As a result of the experiment, the emissivity of the metals increases as the temperature increased. This can be interpreted as a result of increased radiation emission as the thermal movement of internal metal molecules increased.

• 한국환경농학회지
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• 제16권2호
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• pp.124-129
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• 1997

중금속오염폐수처리에 미생물 이용 가능성을 검토하기 위하여 중금속에 강한 내성을 지님과 동시에 균체내 중금속 축적능력이 우수한 중금속 내성균을 분리하여 온도, pH, 및 균체 전배양시간 등과 같은 외부 요인에 따른 균체내 중금속 축적변화를 조사한 결과는 다음과 같다. 중금속화하물 종류에 따른 균체내 중금속 축적량은 $-nitrate(NO_3)$ group을 가진 중금속화합물에서 약간 높았으나 화합물 종류에 따라서 큰 차이는 없었다. 균체 전배양시간에 따른 중금속 축적은 24시간 전배양한 균체에서 높게 나타났으나 전반적으로 전배양시간에 따라서 큰 차이는 없었다. 중금속 내성균의 균체내 중금속 축적은 온도, pH등 외부환경요인에 영향을 받았으며, 중금속 내성균의 중금속 최적축적 온도는 전반적으로 $20{\sim}37^{\circ}C$ 범위였고, 중금속 최적축적 pH는 전반적으로 $6{\sim}8$ 범위였다. 중금속을 처리한 용액중 중금속 내성균의 균체량을 증가시킬수록 균체내 축적된 총 중금속양은 증가되었으나 균체 단위 g당 중금속 축적량은 감소되었으며, 균체량의 증가에 비례해서 중금속 축적량이 증가되지는 않았다.

• 한국기계기술학회지
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• 제20권6호
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• pp.745-750
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• 2018

In this study, the thermal behavior of adaptor housing was analyzed by the numerical method. The boundary conditions used to die casting process were the temperature of molten metal and injection time. As the temperature of the molten metal increased, the tensile strength of the product decreased by the blow hole generated in the molten metal, and the decreasing tendency was gradually decreased. As the injection time of the molten metal increased, the heat flux rose, but the degree of the increase was very small. So, the injection time of the molten metal had little effect on the thermal behavior and diffusion of the adapter housing. As a result, the heat of the molten metal was transferred into the housing and the thermal behavior spread widely.