• 전기학회논문지
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• 제68권1호
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• pp.69-76
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• 2019

Microheaters with different structures were fabricated and compared to find an optimal configuration enhancing the performances of $C_2H_2$ gas sensor. Three temperature sensors were integrated on the surface of the insulation layer over the microheater, and resistance changes were observed to check the generated heat from the microheater. A low operating voltage of 1mV was applied to the temperature sensor to minimize any influence of thermal heat from the resistance type temperature sensor, whereas high voltages in the range between 10 and 20V were applied to the microheater. A microheater structure generating maximum heat at low voltage was determined. The generated heat was verified by the temperature sensors on the top of the $Si_3N_4$ and infrared camera. A long term stability and accuracy of the microheater were observed. The developed microheater was applied to enhance the performances of $C_2H_2$ gas sensor and successfully confirmed that the developed microheater greatly contributes to the improvement of sensitivity and selectivity of gas sensor.

• 한국해양바이오학회지
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• 제11권2호
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• pp.89-93
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• 2019

In this study, the stability of the extracted natural pigments against light, temperature, pH, metal ions, and antimicrobial activity were evaluated in marine bacteria Zooshikella sp. 17TA. The pigment of the strain used in the study was red with maximum absorption at a wavelength of 541 nm. The stability of the pigment was evaluated by measuring the absorbance while preserving for 15 days and examining the retention rate. After 15 days of irradiation, the pigment of this bacterium showed 98% retention in the dark and 91% retention in the temperature range of -20℃ ~ 30℃. When the pH was in the range 4-7, the retention was about 80%, and the retention rate was higher than 85% for all kinds of metal ions except for CuCl₂, ZnCl₂, and KCl. The bacterial pigments showed high stability under the given irradiated pH, temperature, and metal ion conditions and had shown activity against gram-positive strains. These results suggest that this highly conserved microbial pigment can be applied to the food industry.

• 한국가금학회지
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• 제17권2호
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• pp.127-133
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• 1990

가열온도와 시간, pH 및 NaCl 농도가 난백겔의 열안정성에 미치는 영향을 검토하기 위하여 가열처리 후 난백겔의 특성을 검토하였으며 그 결과는 다음과 같다. 난백을 90~$170^{\circ}C$까지 온도와 시간별 가열처리 한 결과. 110~$130^{\circ}C$ 영역에서 경도가 떨어졌으나 온도가 높아짐에 따라서 급격히 증가하였다. 응집성의 경우는 12$0^{\circ}C$까지 감소한 후 $130^{\circ}C$에서 급격히 증가하였다. 명도는 온도가 높아질수록 시간이 길어질수록 낮아졌으며 황색도는 높아졌다. 난백의 경도는 pH 7을 중심으로 산성영역에서는 고온처리가 높았으며 알카리영역에서 밝았다. 고온처리의 경우가 저온처리에 비해 산성영역에서는 보다 밝았으며 알카리 영역에서는 보다 어두웠다. 염의 첨가에 의해 난백의 경도는 저온처리 시에는 큰 변화가 없었으나 고온처리시 다소 증가하였고 응고집성은 저온처리시 서서히 증가하였으며 고온처리시 0.5%까지 급격히 증가하였다. 색택은 고온고리시 명도가 증가하였고 황색도는 감소하였으며 농도별 차이는 크지 않았다.

• 한국산업융합학회 논문집
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• 제23권6_1호
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• pp.881-888
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• 2020

A butterfly valve is a valve that adjusts flow rate by rotating a disc for about 90° with respect to the axis that is perpendicular to the flow path from the center of its body. This valve can be manufactured for low-temperature, high-temperature and high-pressure conditions because there are few restrictions on the used materials. However, the development of valves that can be used in a 600℃ environment is subject to many constraints. In this study, the butterfly valve's stability was evaluated by a fluid-structured interaction analysis, thermal-structure interaction analysis, and seismic analysis for the development of valves that can be used in high-temperature environments. When the reverse-pressure was applied to the valve in the structural analysis, the stress was low in the body and seat compared to the normal pressure. Compared with the allowable strength of the material for the parts of the valve system, the minimum safety factor was approximately 1.4, so the valve was stable. As a result of applying the design pressures of 0.5 MPa and 600℃ under the load conditions in the thermal-structural analysis, the safety factor in the valve body was about 3.4 when the normal pressure was applied and about 2.7 when the reverse pressure was applied. The stability of the fluid-structure interaction analysis was determined to be stable compared to the 600℃ yield strength of the material, and about 2.2 for the 40° open-angle disc for the valve body. In seismic analysis, the maximum value of the valve's stress value was about 9% to 11% when the seismic load was applied compared to the general structural analysis. Based on the results of this study, the structural stability and design feasibility of high-temperature valves that can be used in cogeneration plants and other power plants are presented.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.1005-1009
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• 2001

The application of the ultrasonic nozzle has been extended because it is possible atomization of liquid material. In this study, the driving characteristics of the ultrasonic nozzle on the driving circuit were investigated. And the characteristics of the ceramic oscillator were investigated for the temperature stability. The ceramic oscillator were made the Pb[(Sb$\sub$1/2/,Nb$\sub$1/2/)$\sub$0.035/-(Mn$\sub$1/3/Nb$\sub$2/3/)$\sub$0.065/- (Zr$\sub$x/Ti$\sub$l-x/)$\sub$0.9/]O$_3$with mole ratio of Zr/Ti. The ceramis oscillator were need the curie temperature of the over 300[$^{\circ}C$] for the temperature stability. When the Zr/Ti ratio was 49/51, it's curie temperature is 322[$^{\circ}C$] and the electromechanical coupling factor(k$\sub$p/) and mechanical quality factor(Q$\sub$m/) showed the values of 0.555, 1,214, respectively The resonance frequency of ceramic oscillator were from 40KHz to 45KHz. So that, the driving circuit were made a possibility that the frequency are variable. The driving current of ultrasonic nozzle showed the value of maximum 80[mA]. Also, The surface temperature of ceramic oscillator showed 80[$^{\circ}C$] at driving time 10[min]. We knew that the ultrasonic nozzle had stabile driving above 10[min.].

• 동아시아식생활학회지
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• 제17권3호
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• pp.371-378
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• 2007

Red ginseng has been considered a functional food, and many studies on red ginseng and the prevention of cancer, hypertension, arteriosclerosis and constipation have been conducted. In this study, white bread dough with 1, 2, 3, 4 or 5% red ginseng marc powder was measured by a farinograph, extensograph, amylograph, as well as for pH to evaluate the development time, stability, extensibility, resistance to extension, gelatinization temperature, and maximum viscosity temperature. The ash content of the wheat flour increased with an increasing content of red ginseng marc powder. The gelatinization maximum and the temperature for the gelatinization maximum of the flour-water suspension in the amylograph were not affected by the addition of red ginseng marc powder. The moisture absorption of the wheat flour in the farinograph increased as the content of red ginseng marc powder increased. Also, as the content of red ginseng marc powder increased, dough development time decreased. The extensibility of the dough in the extensograph showed a negative relationship with the amount of red ginseng marc powder added.

• 대한기계학회논문집
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• 제15권2호
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• pp.630-643
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• 1991

The hydrodynamic stability equations are formulated for buoyancy-induced flows adjacent to a vertical, planar, isothermal surface in cold pure water. The resulting stability equations, when reduced to ordinary differential equation by a similarity transformation, constitute a two-point boundary-value(eigenvalue) problem, which was numerically solved for various values of the density extremum parameter R=( $T_{m}$ - $T_.inf./) / ( $T_{o}$ - $T_.inf./). These stability equations have been solved using a computer code designed to accurately solve two-point boundary-value problems. The present numerical study includes neutral stability results for the region of the flows corresponding to 0.0.leq. R. leq.0.15, where the outside buoyancy force reversals arise. The results show that a small amount of outside buoyancy force reversal causes the critical Grashof number $G^*/ to increase significantly. A further increase of the outside buoyancy force reversal causes the critical Grashof number to decrease. But the dimensionless frequency parameter $B^*/ at $G^*/ is systematically decreased. When the stability results of the present work are compared to the experimental data, the numerical results agree in a qualitative way with the experimental data.erimental data.

• 접착 및 계면
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• 제7권1호
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• pp.16-22
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• 2006

본 연구에서는 페놀수지 SMC 제조에 사용되는 수용성 레졸형 페놀-포름알데히드 수지의 열안정성과 경화 발열반응 피크의 변화에 미치는 경화온도 및 경화시간의 영향을 열중량분석기와 시차주사열량계를 사용하여 조사하였다. 수용성 페놀-포름알데히드 수지의 중량감소는 주로 $200^{\circ}C,\;400^{\circ}C$ 그리고 $500^{\circ}C$ 부근에서 세 단계로 발생하였다. 경화된 수지의 $750^{\circ}C$에서 탄화수율은 약 62%~65%이었다. 수용성 페놀수지의 열안정성은 경화온도와 경화시간이 증가할수록 증가하였다. 경화시 발열반응은 약 $120^{\circ}C{\sim}190^{\circ}C$ 사이에서 진행되며, 발열피크의 최대점은 약 $165^{\circ}C{\sim}170^{\circ}C$ 사이에서 관찰되었다. 발열반응 곡선의 형태와 발열피크의 최대점은 주어진 경화온도와 경화시간에 의존하였다. 경화되지 않은 수지에 포함되어 있는 $H_2O$ 및 휘발성분을 제거하기 위하여 경화 또는 성형 전에 적어도 $100^{\circ}C$ 이상에서 약 60분 이상의 열처리가 요구되었다. $130^{\circ}C$에서 120분 동안의 경화는 수용성 페놀-포름알데히드 수지의 발열피크를 사라지게 하며, $180^{\circ}C$에서 60분 동안이 후경화는 수지의 열안정성을 더욱 향상시켜 주었다.

• 한국식품영양과학회지
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• 제28권1호
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• pp.153-160
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• 1999

Storage stability of boiled and freeze dried loach and antioxidative effect of Zanthoxylum schinifolium were studied to confirm the possibility in development of instant choo o tang(Korean traditional loach soup). Packaging and storage temperature did not cause a measurable change in in vitro protein digestibility and trypsin indigestible substrate within 45 days of storage but remarkable quality changes were occurred in all samples stored after 60 days. Vacuum packaging and low temperature storage(4 oC) had some effect in retarding protein quality deterioration due to delaying polyunsaturated fatty acid oxidation. Maximum peroxide value and TBA value were reached in 15 days, and there were a slow(TBA value) and rapid reduction(POV) after peaks were reached. In contrast, increasing brown pigment development and fluorescence intensity continued until 90 days of storage. Treatment of ethanolic extracts from Zanthoxylum schinifolium prior to freeze drying could protect against lipid oxidation of freeze dried loach products.

• Journal of Magnetics
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• 제10권1호
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• pp.33-35
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• 2005

Perpendicular magnetization curves and crystal textures of $[Pd(0.8 nm)/Co(0.8 nm)]_5/FeMn$ multilayers having an exchange-biased perpendicular magnetic anisotropy as a function of FeMn thickness and annealing temperature were measured. As FeMn thickness increases from 0 to 21 nm, the perpendicular exchange biasing field ($H_{ex}$) obtained the maximum value of 130 Oe at FeMn thickness 12 nm. As the annealing temperature increases to $240^{\circ}C$, the H_ex increased from 115 Oe to 190 Oe and the exchange-biased perpendicular magnetic anisotropy disappeared at $330^{\circ}C$.