• Journal of Information Display
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• 제10권3호
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• pp.117-120
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• 2009

A new crystallization method for amorphous silicon, called selective area heating (SAH), was proposed. The purpose of SAH is to improve the reliability of amorphous silicon films with extremely low thermal budgets to the glass substrate. The crystallization time shortened from that of the conventional solid-phase crystallization method. An isolated thin heater for SAH was fabricated on a quartz substrate with a Pt layer. To investigate the crystalline properties, Raman scattering spectra were used. The crystalline transverse optic phonon peak was at about 519 $cm^{-1}$, which shows that the films were crystallized. The effect of the crystallization time on the varying thickness of the $SiO_2$ films was investigated. The crystallization area in the 400nm-thick $SiO_2$ film was larger than those of the $SiO_2$ films with other thicknesses after SAH at 16 W for 2 min. The results show that a $SiO_2$ capping layer acts as storage layer for thermal energy. SAH is thus suggested as a new crystallization method for large-area electronic device applications.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1491-1498
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• 2003

Droplet evaporation can be used to transfer large amounts of energy since heat is transferred across a thin liquid film. Spreading the drop over a larger area can enhance this heat transfer. One method of accomplishing this is to dissolve gas into the liquid. When the drop strikes the surface, a gas bubble nucleates and can grow and merge within the liquid, resulting in an increase in the droplet diameter. In this study, time and space resolved heat transfer characteristics for a single droplet striking a heated surface were experimentally investigated. The local wall heat flux and temperature measurements were provided by a novel experimental technique in which 96 individually controlled heaters were used to map the heat transfer coefficient contour on the surface. A high-speed digital video camera was used to simultaneously record images of the drop from below. The measurements to date indicate that significantly smaller droplet evaporation times can be achieved. The splat diameter was observed to increase with time just after the initial transient dies out due to the growth of the bubble, in contrast to a monotonically decreasing splat diameter for the case of no bubbles. Bursting of the bubble corresponded to a sudden decrease in droplet heat transfer.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1548-1553
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• 2003

An experimental study of the absorption process of water vapor into a lithium bromide solution was performed. For the purpose of development of high performance absorption chiller/hater utilizing lithium bromide solution as working fluid, it is the most effective to improve the performance of absorber with the largest heat transfer area of the four heat exchangers. The experimental apparatus was composed of a plate type absorber which can increase the heat exchange area per unit volume to investigate more detail characteristics instead of the conventional type, horizontal tube bundle type. The size of plate absorbers were made for $0.4m{\times}0.6m$ and the design object of a refrigeration capacity was lRT. In this experiment, three kind plate absorbers which were flat plate, dimple plate and groove plate were used. The results were less than the design object values, that is, the refrigeration capacity was about $0.3{\sim}0.4RT$ and the overall heat transfer coefficient was $500{\sim}600kcal/m^2h^{\circ}C$ at the standard conditions.

• 센서학회지
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• 제17권1호
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• pp.69-74
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• 2008

VOCs (Volatile Organic Compound) sensors were fabricated using $SnO_2$nanowires-based thin films and its gas sensing behaviors were studied. The $SnO_2$ nanowires synthesized from a thermal evaporation process were dispersed in a solution and the sensor film was prepared by dropping the slurry on the substrate with the electrodes and an embedded heater. The gas response (Ra/Rg, Ra: resistance in air, Rg: resistance in gas) to $30{\sim}40$ ppm Benzene, Ethyl Benzene, o-xylene were in the range of $39{\sim}42$, which were significantly higher than those to 50 ppm of CO, $CH_4$ and $C_3H_8$ ($12{\sim}19$).

• Journal of Advanced Marine Engineering and Technology
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• 제28권8호
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• pp.1239-1250
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• 2004

This research was concerned with the enhancement of heat transfer by surfactant added to the aqueous solution of LiBr. Different vertical tubes were tested with and without an additive of normal octyl alcohol. The test tubes are a bare inner surface. a groove inner surface, a corrugated inner surface and a spring inserted inner surface tubes. The additive concentration was about 0.08 mass%. The heat transfer coefficient was measured as a function of the film Reynolds number in the range of 20~200. Experiments were carried out at higher cooling water temperature of $35^{\circ}C$ to simulate an air cooling condition for several kinds of absorber testing tubes. The experimental results were compared with and without surfactant. The enhancement of heat transfer by Marangoni convection effect which was generated by addition of the surfactant is observed in each test tube. Especially, it is clarified that the tube with an inserted spring has the highest enhancement effect.

• 대한기계학회논문집B
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• 제25권9호
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• pp.1237-1244
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• 2001

An experimental study was carried out to identify the various regimes of natural convective pool boiling and to determine the boiling heat transfer curve and Critical Heat Flux(CHF) on a vertical square surface having a 70mm width and a 70mm height. The heater made of copper block with embedded cartridge heaters is submerged in a water tank at atmospheric pressure. As the heat flux increases from 100kW/㎡ to 1.2MW/㎡, the heat transfer regime migrates from the nucleate boiling to the film boiling. The boiling heat transfer data are fitted by Rohsenow type correlation. An explosive vapor generation on the heated surface, whose size and frequency are characterized by the heat flux, is visualized using a high speed digital imaging system.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.116.1-116.1
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• 2016

반도체 가스센서에서는 가연성 및 탄화수소계 가스를 감지 하기 위해서 $100{\sim}500^{\circ}C$ 이상의 동작온도를 필요로 한며, 이에 따라 반도체식 가스센서의 마이크로 히터 소재는 고온에서 열적 안정성이 있는 소재가 요구된다. 현재 상용화되고 있는 반도체식 가스센서는 실리콘(Silicon) 기반의 MEMS 기술을 이용한 가스센서이며, 구조적으로나 성능적 한계가 드러남에 따라 실리콘 이외의 다양한 재료의 MEMS 응용기술 개발이 필요한 실정이다. 본 연구에서는 이러한 실리콘의 재료적 한계를 극복하기 위해 다공성 알루미늄 산화물(AAO)을 기판으로 사용하여 마이크로 히터를 제작하였다. AAO의 제작에 앞서 CMP, 화학연마, 전해연마를 이용하여 적합한 전처리 공정을 선정하였고, AAO 제작 시 온도, 시간, 전압의 변수를 주어 마이크로 히터 기판에 적합한 공정을 탐색하였다. 마이크로 플랫폼은 MEMS 공정으로 제작되었으며, PR(Photo Resist)을 LPR(Liquid Photo Resist)과 DFR(Dry Film Resist)로 각각 2종 씩 선택하여 AAO에 적합한 제품을 선정하였다. 제작된 마이크로 히터는 $1.8mm{\times}1,8mm$로 소형화 하였고, 열손실의 제어를 위해 열확산 방지층을 추가하였다. 구동 온도, 소비전력, 장시간 구동시 안정성의 측정 및 평가는 적외선 열화상 카메라와 kiethly 2420 source meter를 이용하여 측정하였으며, 열확산 방지층의 유 무에 따른 온도 분포 및 소비전력을 비교평가 하였다. 최종적으로는 현재 사용화 되어있는 가스센서들의 소비전력과 비교 평가 하여 논의 하였다.

• 정보저장시스템학회논문집
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• 제3권1호
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• pp.47-53
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• 2007

In this paper, a thermo-piezoelectric mechanism with integrated heaters and piezoelectric sensors has been studied for low power probe-based data storage. Silicon nitride cantilever integrated with silicon heater and piezoelectric sensor has been developed to improve the uniformity of cantilevers. Data bits of 40 nm in diameter were recorded on PMMA film. The sensitivity of the piezoelectric sensor was 0.615 fC/nm after poling the PZT layer. And, the $34\times34$ probe array integrated with CMOS circuits has been successfully developed by simple one-step bonding process. The process can simplify the process step and reduce tip wear using silicon nitride tip.

• International Journal of Air-Conditioning and Refrigeration
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• 제8권2호
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• pp.1-10
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• 2000

This research is concerned with the enhancement of heat transfer by surfactant added to the aqueous solution of LiBr. Different vertical tubes were tested with and without an additive of normal octyl alcohol. The test tubes are a bare tube, a groove tube, a corrugated tube and a spring-inserted tube. The additive concentration is about 0.08 mass%. The heat transfer coefficient is measured as a function of the film Reynolds number in the range of 20~200. Experiments are carried out at higher cooling water temperature of $35^{\circ}C$to simulate an air cooling condition for several kinds of absorber testing tubes. The experimental results with and without surfactant are compared. The enhancement of heat transfer by Marangoni convection effect which is generated by addition of the surfactant is observed in each test tube. Especially, it is clarified that the tube with an spring-inserted has the enhancement effect.

• ETRI Journal
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• 제29권5호
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• pp.667-669
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• 2007

This letter presents a smart integrated microfluidic device which can be applied to actively immobilize proteins on demand. The active component in the device is a temperature-controllable microelectrode array with a smart polymer film, poly(N-isopropylacrylamide) (PNIPAAm) which can be thermally switched between hydrophilic and hydrophobic states. It is integrated into a micro hot diaphragm having an integrated micro heater and temperature sensors on a 2-micrometer-thick silicon oxide/silicon nitride/silicon oxide (O/N/O) template. Only 36 mW is required to heat the large template area of 2 mm${\times}$16 mm to $40^{\circ}C$ within 1 second. To relay the stimulus-response activity to the microelectrode surface, the interface is modified with a smart polymer. For a model biomolecular affinity test, an anti-6-(2, 4-dinitrophenyl) aminohexanoic acid (DNP) antibody protein immobilization on the microelectrodes is demonstrated by fluorescence patterns.