• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.143-146
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• 2009

The metal-supported SOFC has beed developed as a new concept of SOFC which has higher mechanical strength. However, the mass transfer rate in this type of SOFC may be decreased due to the contact layer and the support layer and that can cause the low performance. Therefore, numerical analysis of the heat and mass transfer characteristics in a metal-supported solid oxide fuel cell(SOFC) is studied in this paper. Governing equations and electrochemical equations are calculated simultaneously. And the numerical results are compared with the experimental results for the code validation. The current density, temperature, and pressure drop are suggested as numerical results.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.166-170
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• 1998

The metal transfer of CO2 arc welding machine can be devided into short-circuit(low current) metal transfer. Especially in large crrent region, the main problem of CO2 arc welding machine is much spatter generation which is caused by mainly instant short-circuit matal transfer. So in this paper descrives new current control method in large current region, which can improve welding performance and lessen spatter generation. And as a result of experiment, the effect of proposed control method is demonstrated.

• Journal of Welding and Joining
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• v.17 no.1
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• pp.116-123
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• 1999

The $CO_2$ welding with 100% $CO_2$ shielding gas is commonly used because of its cost and efficiency. Arc phenomena of the $CO_2$ welding is influenced by various factors such as chemical compositions of welding wire, shielding gas, welding condition and welding power source etc. In this study, arc phenomena is investigated by using two type of FCW(titania type, semi-metal type). Then, the welding quality and optimum welding condition can be selected. From this study, the following results were obtained; 1) In low current range(140A), FCW up to welding voltage(22V) resulted in a typical short circuit transfer. 2) In high current range(320A), the arc stability in titania FCW of a typical globular transfer is better than that of semi-metal FCW.

• Journal of Magnetics
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• v.16 no.2
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• pp.92-96
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• 2011

This study investigated theoretically the properties of the spin transfer torque acting on a ferromagnet in a ferromagnet-normal metal-antiferromagnet junction. Earlier work showed that the angular dependence of the spin transfer torque can be a wavy-type if the junction satisfies a special symmetry. This paper reports a simple model analysis that allows a derivation of the wavy angular dependence without taking advantage of the symmetry. This result suggests that the wavy angular dependence can appear even when the symmetry is broken. As an illustration, the angular dependence was calculated as a function of the degree of the compensation at the normal metal-antiferromagnet interface. The implications of the result for the current-induced magnetization precession are discussed.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.15 no.2
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• pp.188-195
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• 1986

Condensation heat transfer can be classified in dropwise condensation and filmwise condensation, and for the industrial purpose, the former is more useful than the latter because of the higher heat transfer rate. But it is difficult to maintain the dropwise condensation continuously since most of the metal surfaces become wetted after exposure to a condensing vapor over an extended period of time. To maintain dropwise condensation continuously , various surface coatings and promoters have been used recently, but these methods must be reconsidered about the durability of condensing surface. Therefore, in this study, evaporating method of various pure metals on the condensing surface has been performed to maintain dropwise condensation. The results have showed that the heat transfer rate of silver evaporating surface is higher than any other metal evaporating in dropwise area. Transition temperature and filmwise condensation curves are uniform regardless of kinds of evaporating metals.

• Journal of Korea Foundry Society
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• v.18 no.3
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• pp.246-253
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• 1998

Precision metal mold casting process is a casting method manufacturing mechanical elements with high precision, having heavy/light alloys as casting materials and using permanent mold. To improve dimensional accuracy and the final mechanical properties of the castings, the solidification speed and the cooling rate of the casting should be controlled with the optimum mold cooling system, and moreover, to obtain more accurate control of the whole process interfacial heat transfer characteristic at the mold/casting interface must be studied in advance. In the present study, aluminum alloy casting system with metal mold equipped with electrical heating elements and water cooling system was designed and the temperature histories at points inside the metal mold were measured during the casting process. The heat transfer phenomena at the mold/casting interface was characterized by the heat flux between solidifying casting metal and metal mold, and the heat flux history was obtained using inverse heat conduction method. The effect of mold cooling condition upon the heat flux profile was examined, and the analysis shows that the heat flux value has its maximum at the beginning of the process.

• Journal of Sensor Science and Technology
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• v.31 no.1
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• pp.12-15
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• 2022

In this study, we studied the effects of transfer gate on the photocurrent characteristics of gate/body-tied (GBT) metal-oxide semiconductor field-effect transistor (MOSFET)-type photodetector. The GBT MOSFET-type photodetector has high sensitivity owing to the amplifying characteristic of the photocurrent generated by light. The transfer gate controls the flow of photocurrent by controlling the barrier to holes, thereby varying the sensitivity of the photodetector. The presented GBT MOSFET-type photodetector using a built-in transfer gate was designed and fabricated via a 0.18-㎛ standard complementary metal-oxide-semiconductor (CMOS) process. Using a laser diode, the photocurrent was measured according to the wavelength of the incident light by adjusting the voltage of the transfer gate. Variable sensitivity of the presented GBT MOSFET-type photodetector was experimentally confirmed by adjusting the transfer gate voltage in the range of 405 nm to 980 nm.

• Journal of Sensor Science and Technology
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• v.30 no.2
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• pp.114-118
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• 2021

In this study, the sensitivity of an active pixel sensor (APS) was adjusted by employing a gate/body-tied (GBT) p-channel metal-oxide semiconductor field-effect transistor (PMOSFET)-type photodetector with a transfer gate. A GBT PMOSFET-type photodetector can amplify the photocurrent generated by light. Consequently, APSs that incorporate GBT PMOSFET-type photodetectors are more sensitive than those APSs that are based on p-n junctions. In this study, a transfer gate was added to the conventional GBT PMOSFET-type photodetector. Such a photodetector can adjust the sensitivity of the APS by controlling the amount of charge transmitted from the drain to the floating diffusion node according to the voltage of the transfer gate. The results obtained from conducted simulations and measurements corroborate that, the sensitivity of an APS, which incorporates a GBT PMOSFET-type photodetector with a built-in transfer gate, can be adjusted according to the voltage of the transfer gate. Furthermore, the chip was fabricated by employing the standard 0.35 ㎛ complementary metal-oxide semiconductor (CMOS) technology, and the variable sensitivity of the APS was thereby experimentally verified.

• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1405-1409
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• 2007

The potential-induced charge transfer of the dye (Bu4N)2[Ru(dcbpyH)2-(NCS)2] (N719) on Au, Ag, and Cu electrode surfaces has been examined by surface-enhanced Raman scattering (SERS) in the applied voltage range between 0.0 and ?0.8 V. N719 is assumed to have a relatively perpendicular geometry with its bipyridine ring on the metal surfaces. A strong appearance of the carboxylate band at ~1370 cm-1 indicates that the carboxyl group will likely be deprotonated on the metal surfaces. As the electric potential is shifted from ?0.8 to 0.0 V, the ν (NCS) band at ~2100 cm-1 on the electrode surfaces appears to undergo a shift in frequency and intensity change. This indicated that the charge transfer between the dye and metal electrode surfaces had occurred. Electric-field-dependent charge transfer differs somewhat depending on the type of metal surfaces as suggested from the dissimilar frequency positions of the ν (NCS) band.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.812-817
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• 1998

Experimental studies on heat transfer and solidification of the molten metal pool with overlying coolant with boiling were performed The simulant molten pool material is tin (Sn) with the melting temperature of 232$^{\circ}C$. Demineralized water and R113 are used as the working coolant. This work examines the crust formation and the heat transfer characteristics of the molten metal pool immersed in the boiling coolant. The Nusselt number and the Rayleigh number in the molten metal Pool region of this study are compared between the water coolant case and the R113 coolant case. The experimental results or the water coolant are higher than those for R113. Also, the empirical relationship of the Nusselt number and the Rayleigh number is compared with the literature correlations measure from mercury. The present experimental results are higher than the literature correlations. It is believed that this discrepancy is caused by the effect of heat loss to the environment on the natural convection heat transfer in the molten pool.