• Journal of the Korean Vacuum Society
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• v.20 no.2
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• pp.77-85
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• 2011

The silicon-germanium (SiGe) alloy, which is compatible with silicon semiconductor technology and has a smaller band gap and a lower thermal conductivity than silicon, has been used to fabricate electronic devices such as transistors, photodetectors, solar cells, and thermoelectric devices. This paper reviews the application of SiGe alloys to electronic devices and related technical issues. Since the SiGe alloy comprises germanium whose band gap is smaller than silicon, its band gap is also smaller than that of silicon irrespective of the ratio of silicon to germanium. This narrow band gap of SiGe enables the base thickness of bipolar transistors to decrease without a loss in current gain so that it is possible to improve the speed of bipolar transistors by adopting the SiGe-base. In addition, the conversion efficiency of solar cells is enhanced by the absorption of long-wavelength light in the SiGe absorption layer. Phonon scattering caused by the irregular distribution of alloying elements induces the lower thermal conductivity of SiGe than those of pure silicon and germanium. Because a thin film layer with a low thermal conductivity suppresses thermal conduction through a thermal sink, the SiGe alloy is considered to be a promising material for silicon-based thermoelectric systems.

• Food Science and Preservation
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• v.16 no.5
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• pp.699-704
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• 2009

Commercially produced 'baby leaves' of Brassica campestris var. narinosa (Chinese cabbage) were used in the present study. Baby leaf vegetables were sown on 128 cell plug trays and harvested 30 days after sowing. For mechanical stress experiments, seedlings were thinned to three per cell, selected for uniformity, and watered at the base. Trays were treated with mechanical stress by stroking back and forth 50 times, using a sheet of A4 paper folded to double thickness. Plants were treated between 12:00 and 14:00 daily for 15-20 days. Harvested baby leaf vegetables were packed in MAP salad bags made of P-plus film, $50{\mu}m$ polypropylene (PP) film, and polyethylene terephthalate (PET) boxes. Fresh weight was well-maintained under P-plus and PP film on storage at $8^{\circ}C$. However, loss of fresh weight occurred quickly in PET boxes, and vegetable quality deteriorated rapidly. Stressed leaves were smaller but thicker, with an increased dry weight ratio. We thus suggest that P-plus or PP film is most appropriate packing for marketing of baby leaf vegetables, which should be stored at $8^{\circ}C$. Our data on baby leaf vegetables also make a significant new contribution in that we demonstrate a positive effect of stress touching on baby leaf processability.

• Food Science and Preservation
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• v.24 no.1
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• pp.60-67
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• 2017

In this study, we tried to establish the best method for fresh blueberry beverage production using enzyme treatment as well as low temperature extraction. During extraction of physiologically functional materials, we used low temperature to prevent nutritional loss by heat. In addition, we investigated optimal blueberry extraction conditions using various enzyme treatments (cellulase, pectinase, cellulase:pectinase (1:1) mixture) to increase extraction efficiency and reduce turbidity. A variety and ratio of enzymes, extraction temperature, extraction time, and shaking speed were considered for the best extraction efficiency rate. We observed high extraction efficiency rates of 85.72-86.55% and 87.06-87.93%, respectively, upon cellulase or pectinase treatment. In addition, a mixture of cellulase:pectinase (1:1) showed an extraction efficiency rate of 86.84-88.14%. The best extraction efficiency rate was observed when crude blueberry was treated at $45^{\circ}C$ (87.91%), for 3 h (87.88%), in a 90 rpm shaker (89.19%). Sugar content and acidity of blueberry extract were not affected by the various treatments. However, total phenolic compounds were detected upon pectinase treatment (18.62 mg/g). Only fructose and glucose as free sugars were found in all samples regardless of treatments and extraction conditions.

• Food Science and Preservation
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• v.24 no.1
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• pp.1-7
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• 2017

This study was conducted to investigate the effects of egg shell calcium treatments on short-term storage of cut Kimchi cabbage. Egg shell ash powder (ESP-2) had the greatest calcium contents. Calcium solubility was greater in citric acid than acetic acid and ascorbic acid. Cut Kimchi cabbages ($3{\times}3cm$) were treated with 0.5%, 1.0%, and 2.0% egg shell powder (ESP-1), and egg shell ash powder (ESP-2), and 0.5% citric acid, put inside polyethylene (PE) bags, and stored at $5^{\circ}C$ for 6 weeks. Weight loss was about 99.85-99.90%, and the ratio was the lowest upon 0.5% ESP-2 treatment (p<0.05). The reduction ratios of soluble solids were 21.3-43.4%, and decreased in the order of 1.0% ESP-2 treatment and 0.5% ESP-1. The $L^*$ values decreased, whereas $a^*$ and $b^*$ values of Hunter colorimetry increased in all treatments. ${\Delta}E$ values were lowest upon 0.5% ESP-2 treatment. 0.5% ESP-2 treatment showed better quality characteristics than other treatments. Thus, egg shell calcium treatments could effectively enhance the shelf-life of cut Kimchi cabbage.

• Korean Journal of Food Science and Technology
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• v.37 no.5
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• pp.806-811
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• 2005

Effects of green tea-soybean paste on weight-changes and serum lipid profiles in rats fed high fat diet were investigated. Sprague-Barley male rats divided into five groups were fed five different diets for 10 weeks: B group, basal diet H group, high fat-diet containing 0.5% cholesterol+15% lard H-S group, high fat diet containing soybean paste H-0.6GS group, high fat diet containing 0.6% green tea-soybean paste H-4GS group, high fat diet containing 4% green tea-soybean paste. H group showed highest weight gain (p<0.05). Addition of green-tea soybean paste to high-fat diet significantly decreased weight gain, H-4GS group showing highest weight loss (p<0.05). No significant differences in food efficiency ratio and total food intake were found among groups. Liver weight of H group was highest. Addition of green tea-soybean paste to high fat diet significantly reduced liver weight (p<0.05, Table 2). Concentrations of glucose, uric acid, bilirubin, and total protein were similar among all group. Mean GPT values of H-4GS group were significantly different from these of H- and H-S groups (p<0.05). H-S, H-0.6GS, and H-4GS groups had significantly lower triglyceride and total cholesterol, and higher HDL than H-group (p<0,05). H-4GS group had significantly lower serum triglyceride than H-0.6GS group (p<0.05).

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1604-1612
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• 1999

The study was carried out to investigate the quality of the wet noodle added with the powders of nopal and nopalitos from Opuntia ficus-indica. The wet noodles were prepared to the ratio of 3, 6 and 9% (w/w) of the nopal and the nopalitos based on a flour weight. The initial pasting temperature and final viscosity in an amylograph decreased as the increase of the nopal and the nopalitos powders. A cooked weight and volume decreased with the increase of the nopal and the nopalitos powders, while a cooking loss increased. From the sensory evaluation, the wet noodles included 3% nopalitos and 6% nopal powders were similarly evaluated as the noodle used whole wheat flour. Bacterial counts of wet noodle with the nopal and the nopalitos powders were always lower than those of the control. Bacterial counts of wet noodle slowly increased as the increase of the amount of nopal and the nopalitos powders during storage at $4^{\circ}C\;and\;20^{\circ}C$. The methanol extracts from the nopal showed antimicrobial activities against Escherichia coli, Escherichia coli O157 : H7, Salmonella typhimurium, and Bacillus subtilis, while the extracts from the nopalitos showed antimicrobial activity only against Escherichia coli.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9B
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• pp.778-790
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• 2004

In this paper, we propose the functional models of optical burst switching (OBS) routers to apply GMPLS (Generalized Multiprotocol Label Switching) to optical networks based on OBS. In addition, we introduce a connection admission control (CAC) algorithms which are operated in this models and can accommodate the required QoS. Firstly, the characteristics of current GMPLS and OBS for the optical Internet are basically considered. With this consideration, the models are proposed to accept OBS features which include the recognition of data bounda η with control information and the statistical multiplexing in terms of bursts. Secondly, we use an offset time decision (OTD) algorithm on behalf of controlling the connection admission with taking QoS parameters such as burst loss rate(BLR) and service-differentiation ratio(SDR) into consideration. The proposed CAC algorithms use the offered load of LSP (Label Switched Path), wavelength information, and QoS parame ‘ ers as inputs of OTD algorithm. A call setup request will be accepted when the offset time decided by OTD algorithm is reasonable for guaranteeing its requested QoS. Simulation is used for performance evaluation Results show the proposed schemes can guarantee the required QoS and those are better than the previous one in terms of channel utilization.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1C
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• pp.103-112
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• 2010

In this paper, we propose a coarse and fine frequency synchronization method which is suitable for the 3GPP(3rd Generation Partnership Project) LTE(Long Term Evolution) FDD(Frequency Division Duplexing) / TDD(Time Division Duplexing) dual mode system. In general, PSS(Primary Synchronization Signal) correlation based estimation method and CP(Cyclic Prefix) correlation based tracking loop are applied for coarse and fine frequency synchronization in 3GPP LTE OFDMA(Orthogonal Frequency Division Multiple Access) system, respectively. However, the conventional coarse frequency synchronization method has performance degradation caused by fading channel and squaring loss. Also, the conventional fine frequency synchronization method cannot guarantee stable operation in TDD mode because of signal power difference between uplink and downlink subframe. Therefore, in this paper, we propose enhanced coarse and fine frequency synchronization methods which can estimate more accurately in multi-path fading channel and high speed channel environments and has stable operation for TDD frame structure, respectively. By computer simulation, we show that the proposed methods outperform the conventional methods, and verify that the proposed frequency synchronization method can guarantee stable operation in 3GPP LTE FDD/TDD dual mode downlink receiver.

• Journal of the Korean Ceramic Society
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• v.39 no.9
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• pp.822-828
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• 2002

Fabrication and electrical characterization of R. F. High-power unit capacitors were investigated to study on condition of fabrication processing for R. F. High-power unit capacitor and electrical characteristics according to addition of $ZrO_2$. The unit capacitors were fabricated using tape casting. The optimum mixture ratio of dielectrics and mixing binder for the slurry fabrication was 57.5∼60.0: 42.5∼40.0 wt%. The slurry viscosity was 4000∼5000 cps and casting state of green tape fabricated using these slurry was excellent. Optimum stacking was made by 200 kg/$cm^2$ pressure with 80$^{\circ}C$ heating. $ZrO_2$ was added to improve the electrical characteristics of unit capacitor, especially breakdown characteristics. The dielectric constant and loss factor of the unit condenser having different $ZrO_2$ amounts was not changed in the addition range of 1 to 5 wt%. Also, dielectric constant was not changed in the frequency range of 10 to 500 kHz. It was found that characteristics of resistance voltage was improved through the formation of $CaZrO_3$ and the reduction of particle size as about 3wt% $ZrO_2$ was added.

• Journal of Bio-Environment Control
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• v.17 no.4
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• pp.319-324
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• 2008

The sweet pepper (paprika) is one of the most important exported vegetable crops in Korea. This study evaluated the storability of sweet pepper fruits between 2 cultivars with different maturities under different storage conditions. The sweet peppers ('Special' and 'Fiesta') were grown in a rockwool hydroponic system, and harvested two different maturities: half-maturity and full-maturity levels. The sweet pepper fruits were stored in MA(non-ventilated) and non-MA(ventilated) conditions at 4 and $9^{\circ}C$ for 20 days. The storability of sweet pepper fruit was the highest in $4^{\circ}C$ MA conditions that remained 5% carbon dioxide and 10% oxygen during the storage. The ethylene concentration in MA condition showed $2{\sim}8{\mu}l/l$ regardless of storage temperatures, cultivars and maturities. The fruits packaged with non-ventilated film, showed lower weight loss, and higher firmness, and there was no different about decay ratio compared to the fruits packed ventilated film. The coloration of semi-matured fruit that colored 50% before storage progressed faster in non-ventilated packaging condition at $9^{\circ}C$, but their color did not changed as same as level of full-matured fruit. The electrolyte leakages and respiratory rate that estimated degree of chilling injury was highest in non-MA(ventilated) conditions of 'Special' full matured fruit placed at room temperature for 3 days following storage at $4^{\circ}C$ for 20 days. It may be suggested that sweet pepper fruit packed sealed (non-ventilated) film and stored at non-chilling temperature can be maintained better quality for long term storage.