• Food Science and Biotechnology
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• v.15 no.3
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• pp.374-379
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• 2006

This study was carried out to investigate the physicochemical properties of frozen pork muscle which has been thawed using the ohmic thawing process, and to establish the optimal ohmic power intensity. The samples were frozen at $-40^{\circ}C$ and thawed at 0, 10, 20, 30, and 40 V by ohmic thawing. Increasing ohmic power intensity correlated with increased thawing rates. The relationship between ohmic power intensity and thawing rate can be represented as a polynomial function. The pH value decreased with increasing ohmic power intensity (p<0.05). With regard to color measurement, the $L^*$, a, and b values of thawing at all ohmic power intensities were not significantly different. The water holding capacity showed a peak value of 41.62% with an ohmic thawing intensity of 30 V. Cooking losses were lowest at the lowest ohmic thawing intensity of 10 V. Thiobarbituric acid reactive substance (TBARS) levels with all thawing processes were slightly higher than that of the control (p<0.05). Increasing ohmic power intensity did not tend to change the total volatile basic nitrogen (TVBN) value.

• Food Science of Animal Resources
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• v.26 no.2
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• pp.223-228
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• 2006

This study was carried out to investigate the effects of ohmic power intensity on the physico-chemical properties of hamburger patties. Six different ohmic power intensities (0, 10, 20, 30, 40, and 50V) were delivered by controlling the power with the sine wave at 50Hz. The ohmic power intensity influenced the thawing rate, and increasing ohmic power intensity increased the thawing rate. The faster thawing rate was obtained at higher ohmic power intensity (50V) with 0.5% NaCl added meat patties in comparison to no NaCl added hamburger patties. The pH values of all patties were not significantly different with increasing ohmic power intensity (p<0.05). Increasing thawing rate did not tend to improve the water holding capacity (WHC) of all patties by ohmic thawing. Cooking losses were almost the same regardless of increasing ohmic power intensity. Increasing ohmic power intensity tended to increase the thiobarbituric acid reactive substance (TBARS) levels. TBARS levels of all hamburger patties without NaCl were significantly higher than that of 0.5% NaCl added hamburger patties (p<0.05) at higher ohmic intensity (50V). In conclusion, these results indicated that a higher ohmic power intensity at 50 V induced the lipid oxidation of all patties.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2004.10a
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• pp.321-325
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• 2004

본 연구는 Ohmic heating system을 이용하여 돈육을 해동하여 해동에 의한 식육의 손상을 최소화하고 신선육과 유사한 해동육을 얻기 위해 최적 해동 속도에 대한 기초 자료를 마련하고자 실시하였다. 각각의 ohmic power intensity(AC, 0, 10, 20, 30, 40 Volt)에 따른 돈육의 해동속도는 기하학적으로 중심부 변화에서 가장 빠른 해동속도는 40V에서 1,582 cm/h로 산출되었고 OV의 0.307cm/h에 비하여 약 5배 정도 빠르게 나타났으며 power intensity가 증가할수록 해동속도가 증가하였다. 이와 같이 ohmic intensity(X: volt)와 해동속도(Y: cm/h)변화를 수학적으로 나타내었는데 다음과 같다; lnY=-0.8971+$1.0345{\cdot}X$ $R^2=0.9968$. 각각의 ohmic power와 비교에서 대조구인 신선육의 보수력이 가장 높았고 해동시료인 처리구간 비교에서 power가 상대적으로 높은 30V, 40V에서 보수력이 가장 좋게 나타났다. Cooking loss에서는 power intensity에 따른 유의적인 변화는 발견되지 않았다. Colo에서는 b-값의 경우 ohmic power intensity가 증가함에 따라 다소 감소하는 경향을 보여 주었다. 해동시 power intensity가 증가할수록 pH는 다소 낮아지는 경향을 보여주었다. 또한 육의 TBA가는 이와 반대로 ohmic thawing은 육의 TBA가를 증가시키는 요인으로 작용하였는데, power intensity에 따른 변화는 유의적인 차이를 보여주지 않았다. 그러나 VBN가에서는 신선육에 비해 해동육의 VBN은 증가하였지만 해동방법에 따른 차아는 발견되지 않았다.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2004.10a
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• pp.407-411
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• 2004

Ohmic heating occurs when an electric current is passes through food, resulting in a temperature rise in the product due to the conversion of the electric energy into heat. The time spent in the thawing is critical for product sterility and quality. The objective of this study is to conduct numerical modelling between the effect of ohmic thawing intensity on PTT(phase transition time) at constant concentration and the effect of matrix concentrations on PTT at constant voltage condition. the stronger ohmic thawing intensity resulted in decreasing the PTT. High ohmic intensity causes short PTT. And the higher gelatin concentration, the faster increment of PTT. A numerical modeling was executed to predict the PTT influenced by the power intensity using exponential regression and the PTT influenced by gelatin concentration using logarithmic regression. Therefore, from this numerical model of gelatin matrix, it is possible to estimate exact values extensively.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1061-1064
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• 2009

Through dark injection space-charge-limited current (DI-SCLC) and trap-free SCLC measurements, it has been demonstrated that an indium tin oxide (ITO)/buckminsterfullerene ($C_{60}$) electrode can form a quasi-Ohmic contact with N, N'-bis (naphthalen-1-yl)-N, N'-bis(phenyl) benzidine (NPB). The DI-SCLC results show a clear peak current along with a shift of the peak position as the field intensity varies, implying an Ohmic (or quasi-Ohmic) contact. A theoretical simulation of the SCLC also shows that ITO/$C_{60}$ forms an Ohmic contact with NPB. The Ohmic contact makes it possible to estimate the NPB hole mobility through the use of both DI-SCLC and trap-free SCLC analysis. This also contributes to a reduction in power consumption.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.7
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• pp.610-614
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• 2008

In this work, the electrical and optical properties of the two different p-type GaN electrode schemes, ZnNi/ITO and ZnNi/Au, were compared each other, and applied to the top-emitting GaN/InGaN light-emitting diodes (LEDs). The ZnNi/ITO electrode showed much higher transmittance (90%) and slightly lower contact resistance $(1.27{\times}10^{-4}{\Omega}cm^2)$ than those (77%, $(2.26{\times}10^{-4}{\Omega}cm^2)$) of the ZnNi/Au at a wavelength of 460 nm. In addition, GaN LEDs having ZnNi/ITO showed accordingly higher light output power and luminous intensity than those having ZnNI/Au did at the current levels up to 1 A.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.5.1-5.1
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• 2009

Organic photovoltaic (OPV)cells have attracted considerable attention due to their potential for flexible, lightweight, and low-cost application of solar energy conversion. Since a 1% power conversion efficiency (PCE) OPV based on a single donor-acceptor heterojunction was reported by Tang, the PCE has steadily improved around 5%. It is well known that a high parallel (shunt)resistance and a low series resistance are required simultaneously to achieve ideal photovoltaic devices. The device should be free of leakage current through the device to maximize the parallel resistance. The series resistance is attributed to the ohmic loss in the whole device, which includes the bulk resistance and the contact resistance. The bulk resistance originated from the bulk resistance of the organic layer and the electrodes; the contact resistance comes from the interface between the electrodes and the active layer. Furthermore, it has been reported that the bulk resistance of the indium tin oxide (ITO) of the devices dominates the series resistance of OPVs for a large area more than $0.01\;cm^2$. Therefore, in practical application, the large area of ITO may significantly reduce the device performance. In this work, we investigated the effect of sheet resistance ($R_{sh}$) of deposited ITO on the performance of OPVs. It was found that the device performance of polythiophene-fullerene (P3HT:PCBM) bulk heterojunction OPVs was critically dependent on Rsh of the ITO electrode. With decreasing $R_{sh}$ of the ITO from 39 to $8.5\;{\Omega}/{\square}$, the fill factor (FF) of OPVs was dramatically improved from 0.407 to 0.580, resulting in improvement of PCE from $1.63{\pm}0.2$ to $2.5{\pm}0.1%$ underan AM1.5 simulated solar intensity of $100\;mW/cm^2$.