• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.4
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• pp.213-220
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• 2009

In order to predict the risk of freeze injury for 'Changhowon Hwangdo' peach trees, we used the dormancy depth (i.e., the daily chill unit accumulation during the overwintering period) as a proxy for the short-term, physiological tolerance to freezing temperatures. A Chill-days model was employed and its parameters such as base temperature and chilling requirement were optimized for peach trees based on the 12 observational experiments during the 2008-2009 winter. The model predicted the flowering dates much closer to the observations than other models without considering dormancy depth, showing the strength of employing dormancy depth into consideration. To derive empirical equations for calculating the probabilistic freeze risk, the dormancy depth was then combined with the browning ratio and the budburst ratio of frozen peach fruit branches. Given the exact date and the predicted minimum temperature, the equations calculate the probability of freeze damages such as a failure in budburst or tissue browning. This method of employing dormancy depth in addition to freezing temperature would be useful in locating in advance the risky areas of freezing injury for peach trees production under the projected climate change.

• Journal of the Korean Magnetics Society
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• v.15 no.5
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• pp.282-286
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• 2005

Ni-Cu-Zn ferrites were prepared by the co-precipitation and ferrite microwave absorbers on low temperature sintering were investigated in this work. The properties of its microwave absorbing and physical were analyzed into variations of Ni addition, calcination temperature, sintering temperature. From the analysis of X-ray diffraction patterns, we can see that all the particles have only a single phase spinel structure. In addition, the powders particle size distribution obtained the nano size. By increasing the Ni additive, the permeability of the powders was decreased and the loss factor increased at sintering temperature $1100^{\circ}C$. Also, we considered that it can used high frequency rage. We found that the $(Ni_{0.7}Cu_{0.2}Zn_{0.1}O)_{1.02}(Fe_{2}O_3)_{0.98}$ appeared microwave absorbing properties better than other composition.

• Journal of the Korean Electrochemical Society
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• v.8 no.4
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• pp.149-154
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• 2005

Fuel cell performance evaluation logic was developed using G-language (LabVIEW) to measure performance stability. Degree of stability and reliability of performance data were improved with averaged value and standard deviation method. Water injection system was introduced and the performance using this method was comparable to that of conventional humidification method. Water injection system has advantage of lowering operation energy consumption, reducing the number of parts needed in humidification, therefore increasing efficiency of fuel cell system. Fuel cell performance was decreased in case of low temperature operation such as sub freezing condition. Air purge method was tested to reduce the water content in cell fixture before sub freezing condition. The performance degradation due to low temperature operation was minimized by air purge method in medium size cell fixture ($25cm^2$) case.

• Korean journal of food and cookery science
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• v.11 no.1
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• pp.9-12
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• 1995

The molar ratio of sterol to phospholipid differed from yeast strains, and the ratio was relatively higher in non-freeze-tolerant yeast strain, S. cerevisiae than freeze-tolerant yeast strains, D$\sub$2-4/ or CFY. Phospholipid composition of these yeast were also investigated. Phosphatidylcholine content was larger among phospholipids in all yeasts. Higher ratio of PC/PE was found in freeze-tolerant yeast than non-freeze-tolerant yeast. Higher proportion of linolein acid(18 : 2) against total fatty acid attached to phospholipid was observed in D$\sub$2-4/ than S. cerevisiae or CFY, and the degree of unsaturation of fatty acid was higher in D$\sub$2-4/ and CFY than in S. cerevisiae. These results suggested that the fluidity of yeast cell membrane was different in yeast strains, which might result in the difference in freeze-injury of yeast at low temperatures.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.15 no.1
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• pp.17-23
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• 2009

Current status on consumption and packaging of sweet persimmons in USA was surveyed by visiting the market, and three sea shipments were conducted as model export trial from Korean to USA with measurement in ship container temperature and fruit quality. Strategy to promote the export of Korean persimmons was derived. There have been gradual decrease in the price of persimmons due to their increases production, but there seems potential growth in consumption of the fruits from Asian, Hispanic and American people. Compared to the fruits from other countries, Korean persimmons are desired to have higher soluble solid content with stronger red color, but too large sizes are not favored in American market. There has often been temperature fluctuation in shipment container during the sea transport to USA, resulting in surface blackening, skin black spotting and flesh softening. Plastic bag packages with inappropriate unitizing crimping were found to sometimes build up unproper modified atmosphere (high $O_2$ and low $CO_2$) giving high rate of physiological injury.

• Microbiology and Biotechnology Letters
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• v.29 no.1
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• pp.50-55
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• 2001

A new bacteriocin produced by Bacillus subtilis cx1, was partially purified and characterized. The bactericoin from B. subtilis cx1 was stable in the range of pH 2.5-9.5. B. subtilis csx1 retained its antimicrobial activity to long-term exposure at $-20^{\circ}C$ and $-70^{\circ}C$. However, B. subtilis cx1 was inactivated completely within 15 min over $60^{\circ}C$ and lost 50% of its antimicrobial activity within 15 min at $50^{\circ}C$, B. subtilis cx1 was inactivated by protease, trypsin, proteinase K and carboxypeptidase, which indi-cates its protein nature. Direct detection of the antimicrobial activity on Tricine -SDS-PAGE suggested an apparent molecular mass of about 9,500 dalton.

• Horticultural Science & Technology
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• v.17 no.2
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• pp.118-122
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• 1999

Quality changes of fruit vegetables were investigated during simulated export and marketing to find out the optimum shipping temperature. Fruit vegetables were loaded into a small refrigerated-container and kept for four days at various temperatures, and fruit quality was assayed immediately after harvest, 4 days after storage and 4 days after marketing at ambient temperature. In 'Back Seong Ilho' cucumber fruits, fresh weight loss was further reduced at $13^{\circ}C$ and $11^{\circ}C$ than at $15^{\circ}C$ and room temperature. Soluble solid contents remained at relatively lower levels when cucumbers were stored at $13^{\circ}C$ and $11^{\circ}C$. In 'Chun Ryang' eggplant fruits, fresh weight loss was greatly increased at all the temperatures (room, $12^{\circ}C,\;9^{\circ}C,\;and\;6^{\circ}C$). However, flesh browning, a primary quality factor of eggplant fruit, was most effectively inhibited at $9^{\circ}C$, whereas chilling injury occurred in fruit flesh at $6^{\circ}C$. Water loss of 'Eals Seinu' melon fruits was most inhibited and soluble solid contents at harvest were maintained for the longest period at $4^{\circ}C$. In 'Pe Pe' cherry tomatoes, storage at $10^{\circ}C$ and $7^{\circ}C$ seemed to more effectively inhibit metabolic changes and the incidence of cracking, the severest disorder than room temperature. But the fruits stored at $10^{\circ}C$ contained higher level of soluble solids than those at $7^{\circ}C$. The overall results suggest that the optimum shipping temperature range is 11 to $13^{\circ}C$ for cucumbers, around $9^{\circ}C$ for eggplant fruit, $4^{\circ}C$ for melons, and $10^{\circ}C$ for cherry tomatoes.

• Horticultural Science & Technology
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• v.33 no.5
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• pp.687-696
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• 2015

Black mini tomato 'Hei-G' fruits were harvested at different stages of maturity (immature-mature green and mature-black red) and stored at different temperatures (8, 12, and $20^{\circ}C$) to investigate the quality and lycopene content during storage. Weight loss increased dramatically at higher temperature for both harvesting stages without significant differences. Firmness of immature fruits decreased below the initial level of mature fruit (8.1N) after 5, 8, and 19 days storage, when they were stored at 20, 12, and $8^{\circ}C$, respectively. Soluble solid contents of mature fruit increased at initial storage, and were higher as compared to immature fruits before deterioration at each storage temperature. Decrease in titratable acid of mature fruits depended on storage time and temperature. However, titratable acid of immature fruits showed little change during storage, and so it did not affect flavor. Hunter a value changed greatly in immature fruit stored at high temperature. Unlike ripe tomatoes, there was no significant difference in black tomato Hunter b values of immature and mature fruit at initial and 12 days storage. However, immature fruits stored at $8^{\circ}C$ did not reach full maturity and color development and ripening. High storage temperature increased lycopene production while low storage temperature blocked lycopene development. Shelf life of the immature fruits, which was evaluated by elapsed days to conventional mature stage, was 12 and 15 days when they were stored at 20 and $12^{\circ}C$, respectively. The optimum storage temperature to maintain the quality and lycopene content of mature fruits was $12^{\circ}C$. Moreover, the shelf life of mature fruits stored at $20^{\circ}C$ could reach up to 5 days.

• Food Science and Preservation
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• v.18 no.4
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• pp.442-458
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• 2011

Among Cucubitaceae, melon (Cucumis melo) is one of the most diversified fruits, with various forms, sizes, pulps, and peel colors, In addition, it is a commercially important crop because of its high sweetness, deep flavor, and abundant juice. In the species, there are both climacteric and non-climacteric melons depending on the respiration and ethylene production patterns after harvest. Ethylene is also considered a crucial hormone for determining sex expression, Phytohormones other than ethylene interact and regulate ripening, There are some indices that can be used to evaluate the optimum harvest maturity. The harvest time can be estimated after the pollination time, which is the most commonly used method of determining the harvest maturity of the fruit. Besides the physiological aspects, the biochemical alterations, including those of sweetness, firmness, flavor, color, and rind, contribute to the overall fruit quality. These changes can be categorized based on the ethylene-dependent and ethylene-independent phenomena due to the ethylene-suppressed transgenic melon. After harvest, the fruits are precooled to $10^{\circ}C$ to reduce the field heat, after which they are sized and packed. The fruits can be treated with hot water ($60^{\circ}C$ for 60 min) to prevent the softening of the enzyme activity and microorganisms, and with calcium to maintain their firmness. 1-methylenecyclopropene (1-MCP) treatment also maintains their storability by inhibiting respiration and ethylene production. The shelf life of melon is very short even under cold storage, like other cucurbits, and it is prone to obtaining chilling injury under $10^{\circ}C$. In South Korea, low-temperature ($10^{\circ}C$) storage is known to be the best storage condition for the fruit. For long-time transport, CA storage is a good method of maintaining the quality of the fruit by reducing the respiration and ethylene. For fresh-cut processing, washing with a sanitizing agent and packing with plastic-film processing are needed, and low-temperature storage is necessary. The consumer need and demand for fresh-cut melon are growing, but preserving the quality of fresh-cut melon is more challenging than preserving the quality of the whole fruit.

• Horticultural Science & Technology
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• v.31 no.2
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• pp.186-193
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• 2013

Potential of consumer unit packaging was investigated for quality maintenance during export simulation in king oyster mushrooms (Pleurotus eryngii). Mushrooms were harvested in late May, precooled to $4^{\circ}C$ within 6 hours, and then packaged for shipping in two ways: 2 kg bulk packaging in a polyethylene (PE) bag or three types of unit packaging methods such as 400 g in polypropylene film bag (PPB), 200 g on styrofoam tray + PE shrinkage film wrapping (STW), and 200 g in polyethylene terephthalate (PET) containers (PETC). For local distribution of bulk-packaged commodity, mushrooms were sorted again and packaged into 3 consumer units in the same way as for the initial shipping packages. Simulation of refrigerated container shipping was performed in a walk-in type pilot storage at $0.5^{\circ}C$ for 5 weeks, while local marketing simulation was carried out on the shelf at $7^{\circ}C$ for 7 days. During the shipment simulation, creation of modified atmosphere (MA) was substantial in 2 kg bulk packages with low $O_2$ below 2% and high $CO_2$ over 15% whereas, in PPB and PETC unit packages, relatively higher $O_2$ concentrations were observed. On the shelf at $7^{\circ}C$, $CO_2$ concentrations rapidly increased in PPB and PETC packages despite the short marketing period. Overall marketability evaluated by off-flavor, browning, and texture rating was maintained at excellent level when 2 kg bulk packaging in PE or unit packaging in PPB and PETC were used for shipment. In contrast, establishment of MA was very slight in STW packages during shipment and local distribution resulting in poor quality after export simulation. The results suggested that shipment using adequate consumer unit packaging is more practical and economically beneficial than using bulk packaging in the export program consisting of 5-week shipment and 7-day local distribution.