• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.25-28
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• 2004

A fracture was generated by change of clearance and deterioration of material properties on the sheet metal through temperature. This paper describes the results of a prediction about the temperature of the sheet metal during continuous stamping process, because the temperature increase of the sheet metal has a detrimental effect on formability. To analyze the temperature increase of the sheet metal during continuous stamping process, tensile and friction tests were performed from room temperature to 300$^{\circ}C$ at warm condition in this study. As temperature increase, tensile strength, elongation, strain hardening exponent and anisotropy coefficient for each specimens were decreased. On the other hand, friction coefficients were increased. From the FE-simulation results, temperature upward tendency was identified on dies and sheet metal. These observations are rationalized on the basis of the material properties, friction coefficient vs. temperature relationship for the sheet.

• 한국화재소방학회논문지
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• 제28권1호
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• pp.26-30
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• 2014

보상식 화재 감지기는 일정한 온도 상승률 이상으로 빠르게 상승하는 경우에 작동하는 차동식 화재 감지기의 기능과 정온점에 이르렀을 때 작동하는 정온식 화재 감지기의 기능을 모두 가진 감지기다. 이 화재 감지기는 정온점 이하에서 발생하는 화재를 감지하지 못하는 정온식 화재 감지기의 단점과 불꽃없이 천천히 타는 현상과 같이 천천히 열이 증가하는 화재를 감지하지 못하는 차동식 화재 감지기의 단점을 보완하기 위해 개발된다. 이것을 위해 우리는 이 감지기의 센서로 금속-절연체 전이 임계온도센서를 이용했는데 이 센서의 감도를 결정하는 저항온도계수가 $55^{\circ}C$일 때 14.15%로써, 서미스터(약 0.5%)보다 큰 값이다. 이 센서는 하나의 센서가 정온점 이하에서는 차동 기능, 정온점 이상에서는 정온 기능을 모두 가진다.

• 한국환경과학회지
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• 제8권3호
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• pp.371-377
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• 1999

The effects of benzamidoxime concentration, solvents and temperature on the degree of metal extraction were investigated to apply benzamidoxime to heavy metal extraction as chelating agent. Benzamidoxime was synthesized from benzonitrile with hydroxylamine. The chemical structure of benzamidoxime was identified. The degree of heavy metal extraction was increased with increasing the concentration of benzamidoxime and decreasing the extraction temperature. Benzamidoxime was found to be an concentration of benzamidoxime and decreasing the extraction temperature. Benzamidoxime was found to be an effective extractant for Cu-extraction by benzene or chloroform. The relationship between the thermodynamic overall equilibrium constant and absolute temperature was expressed as log K = -5.56 ＋ $855T^{-1}$. Heat of extraction, $$\Delta$H^0$ were calculated from overall equilibrium constants at various temperature and the extraction reactionby benzamidoxime was found to be exthothermic.

• Journal of the Optical Society of Korea
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• 제7권2호
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• pp.84-88
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• 2003

A new method for temperature compensation of fiber Bragg grating (FBG) using hi-metal is proposed and experimentally demonstrated. Bi-metal bends toward the metal of low temperature expansion coefficient as the temperature increases, and this property is utilized to cancel the thermo-optic effect of the fiber. The optimum thickness of the high coefficient metal was empirically found by the trial-and-error method. The temperature sensitivities were 8.1 pm/$^{\circ}C$ and -0.018 pm/$^{\circ}C$ for the uncompensated and compensated FBGs, respectively, which indicates a reduction to a mere 0.22 % of the original sensitivity. No appreciable change in the spectral shape was observed. The packaging technique described in this paper is simple and compact, and it can be used for FBGs in WDM and DWDM communication systems that have stringent requirements on the temperature stability of the components.

• Journal of Welding and Joining
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• 제21권2호
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• pp.82-88
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• 2003

The bonding phenomenon and mechanism in the transient liquid phase bonding(TLP Bonding) of directionally solidified Ni base superalloy, GTD-111 was investigated. At the bonding temperature of 1403K, liquid insert metal was eliminated by isothermal solidification which was controlled by the diffusion of B and Si into the base metal and solids in the bonded interlayer grew epitaxially from mating base metal inward the insert metal. The number of grain boundaries formed at the bonded interlayer was corresponded with those of base metal. The liquation of grain boundary and dendrite boundary occurred at 1433K. At the bonding temperature of 1453K which is higher than liquation temperature of grain boundary, liquids of the Insert metal were connected with liquated grain boundaries and compositions in each region mixed mutually. In Joints held for various time at 1453t phases formed at liquated grain boundary far from the interface were similar to those of bonded interlayer. With prolonged holding time, liquid phases decreased gradually and liquids of continuous band shape divided many island shape. But liquid phases did not disappeared after holding for 7.2ks at 1453k. Isothermal solidification process at the bonding temperature which is higher than the liquation temperature of the grain boundary was controlled by diffusion of Ti to be result in liquation than B or Si. in insert metal. (Received January 15, 2003)

• Journal of Welding and Joining
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• 제14권1호
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• pp.47-56
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• 1996

The purpose of this study is to develope an insert metal which can be brazed at lower temperature than the conventionally used insert metal and provide higher strength joint than base metal. In the review of binary phase diagram concerning Ti, Cu and Ni resulted in the discovery of Si having eutectic composition with them. The microstructure and the distribution of elements in reaction zone between CP Ti and insert metal were investigated by Optical Microscopy, SEM/EDX, EPMA, X-RAY. The newly developed insert metal is Ti-15wt%Cu-18wt%Ni-2wt%Si, which can yield the lower brazing temperature(1183K) compared with the conventional Ti-Cu-Ni system insert metal. The joints with this insert metal had tensile strength of 385MPa in the bonding temperature range of 1183K to 1243K.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.86-87
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• 2005

Aluminum(Al) sputtering is best known method to form Al film for the Si wafer in the process of 180nm and above. In the Al metal line process, one of the frequently founded and well-known defect was metal depression. In this paper, several experiments were performed such as temperature, Ar gas flow rate, thickness change in other to reduce the metal depression and find the origination of metal depression. Through experiments, it is found that metal depression was significantly related to the temperature. And the Ar gas flow rate did not influence to the creation of depression. The off status ESC also showed stable metal film without depression by same mechanism of temperature decrease. Also, thickness is strongly influence to the metal depression.

• 조명전기설비학회논문지
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• 제26권3호
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• pp.40-45
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• 2012

We substantially increased the temperature sensitivity of a fiber Bragg grating temperature sensor by gluing it onto a piece of bi-metal strip. The temperature-induced Bragg wavelength shift is increased upto 5 times more than that of the intrinsic FBG sensor by the strain effect from the deflected bi-metal. We showed the feasibility of the proposed sensor by comparing the temperature measuring experiments with those of the intrinsic FBG sensors. Also we measured temperature varying the length of the bi-metal pieces and analyzed the result effect of it.

• International Journal of Air-Conditioning and Refrigeration
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• 제14권3호
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• pp.94-101
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• 2006

A theoretical investigation to find thermodynamically optimum design conditions of conduction-cooled Peltier current leads is performed. A Peltier current lead (PCL) is composed of a thermoelectric element (TE), a metallic lead and a high temperature superconductor (HTS) lead in the order of decreasing temperature. Mathematical expressions for the minimum heat flow per unit current crossing the TE-metal interface and the minimum heat flow per unit current from the metal lead to the joint of the metal and the HTS leads are obtained. It is shown that the temperature at the TE -metal interface possesses a unique optimal value that minimizes the heat flow to the joint and that this optimal value depends on the material properties of the TE and the metallic lead but not the joint temperature nor electric current. It is also shown that there exists a unique optimal value for the joint temperature between the metal and the HTS leads that minimizes the sum of the power dissipated by ohmic heating in the current leads and the refrigerator power consumed to cool the lead, for a given length of the HTS.

• Journal of Welding and Joining
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• 제32권1호
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• pp.66-70
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• 2014

In Ti active brazing of YSZ to STS 430 using Ag-Cu Filler Metal, the effect of Ti contents on the shear bonding strength were investigated together with the effect of brazing temperature and holding time. The addition of Ti in Ag-Cu Filler Metal increased the bonding strength up to 4.68% Ti, followed by the decrease with further addition. This seems to be caused by formation of TixOy at the reaction layer. Brazing temperature was optimized at $960^{\circ}C$ among a given temperature ranges. The addion of Sn to Ag-Cu filler metal brought the decrease of its melting temperature its melting temperature without a significant decrease of bonging strength.