• The Korean Journal of Pesticide Science
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• v.17 no.1
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• pp.72-75
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• 2013

This study was performed to investigate the susceptibility and control efficacy of 27 registered insecticides against pear psylla, Cacopsylla pyricola in laboratory and field (Jincheon). Mortality of 3rd instar of C. pyricola was higher treated with pyrifluquinazon WG (97.7%), flonicamid WG (94.7%), abamectin EC (92.8%), and acetamiprid+buprofezin EC (86.8%) sprayed with field recommended concentration using a prayer in laboratory. These four insecticides also showed control effects of > 90% at 5 days after treatment in field.

• The Korean Journal of Community Living Science
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• v.20 no.1
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• pp.5-17
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• 2009

The objective of this study was to analyze the factors regarding work-related musculoskeletal disorders (MSDs) in fruit-growers and offer the fundamental data for work improvement. The 587 fruit-growers (409 males and 178 females) working with 5 kinds of fruit: apple, pear, peach, grape, and mandarin participated in a questionnaire survey regarding MSDs and health condition in 2004 and 2005. The results are as follows: 1. Smoking rate was highest in apple growers. 2. Drinking rates were highest in male peach growers and in female grape growers. 3. Regular exercise rates were higher in pear and mandarin growers. 4. Physical and mental fatigue was higher in females than in males in most cases. 5. The prevalence rate of medically diagnosed diseases was highest for osteoarthritis (16.4%), herniated nucleus pulposus (HNP, 13.5%), and chronic gastritis/gastric ulcer (10.5%). As well as, the prevalence of dermatosis was higher in pear and mandarin growers. 6. The prevalence rate of musculoskeletal symptoms among the various pain areas was highest for lower back, shoulders, and knees. The prevalence rate was also high for lower back, shoulder, and knee pain in apple and grape growers. 7. The significant indexes used determining the musculoskeletal symptoms were BMI, working period, and regular exercise. These results can be practically used for work improvement for the fruit-growers to prevent MSDs.

• Korean Journal of Organic Agriculture
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• v.19 no.2
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• pp.273-282
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• 2011

This study was conducted to investigate the effects of germanium (Ge) application types on the nutrient concentrations in soil and leaves and leaf characteristics in a 'Niitaka' pear orchard in 2004. Ge application included foliar application, fertigation in soils, trunk injection, and the three-combined application. All Ge treatedplots had lower soil $NO_3$-N, K, and Ca concentrations than those of control plot. Ge concentrations in Ge treated-soils were approximately 50 times higher than those of the control. Ge applications significantly increased area, dry weight, and specific weight in leaves compared to the control. Control treated-trees had greater K concentrations in leaves than the Ge treated-trees, which was oppositively observed for the leaf Ca; leaf Ca was higher on the Ge treated-trees than control. Leaf Ge concentrations were significantly higher on the Ge treated-trees compared to the control, except for the Ge fertigation. Ge concentrations in fruits were greater on the Ge-treated trees than the control trees.

• Korean Journal of Agricultural Science
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• v.38 no.3
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• pp.405-411
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• 2011

In this study, we evaluated the changes of fruit quality indices during fruit development and ripening in Korean new pear cultivar 'Wonhwang' and 'Whasan' to determine appropriate harvest time and to enhance the marketability. The fruit of each cultivar harvested from 100 days after full bloom (DAFB) to 135 and 150 DAFB in 'Wonhwang' and 'Whasan', respectively. The fruit growth of both cultivars showed a typical single sigmoidal pattern. Flesh firmness of two cultivars decreased continuously with fruit development and ripening, reaching a final level of about 2.6 kgF at harvest stage. The starch content of fruit sap was much higher in the fruits of early development stage than the later stage of fruit ripening. In 'Wonhwang' pears, the starch level decreased coincide with fruit ripening (130 DAFB), while that of 'Whasan' decreased from very early stage of fruit development (120 DAFB), 30 days before full ripe. 'Whasan' pear showed much lower acidity level of about 0.13% during fruit development and ripening period compared with that of 'Wonhwang'. Therefore, the ratio of soluble solids to total acidity (TSS/acid) increased gradually with fruit development and ripening, reaching a final level of 80 and 98 in 'Wonhwang' and 'Whasan', respectively. There were no climateric rise of fruit respiration during fruit ripening periods in two oriental pear cultivar. The changes of skin color difference including hunter vale $a^*$ which means loss of green color occurred only after onset of ripening in two cultivars.

• The Korean Journal of Food And Nutrition
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• v.30 no.1
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• pp.139-147
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• 2017

The objective of this study was to develop anti-browning agents for commercial ready-to-eat pear products, which are preferred not only to maintain the flavor, color and texture of pears, but also to increase consumers' preference. The sliced 'Shin-go (Niitaka)' pears were immersed in 5% and 10% oxidized starch, 1% citric acid, and 5% and 10% oxidized starch with addition of 0.1% sucralose for 3 minutes, and then they were packaged in vacuum sealed bags at $1^{\circ}C$ for 9 days. In order to evaluate the quality of packaged sliced pears, the quality index was determined in terms of color, firmness, soluble solids, and sensory quality. With the passage of storage time, no specific variation in firmness and soluble solids was observed. However, the ${\Delta}E$ value of the sliced pears treated with 5% oxidized starch solution was significantly lower than that of the other pears. Also, the Hunter L and b values of the sliced pears treated with 5% oxidized starch solution remained nearly constant from the beginning of storage. This observation shows that 5% oxidized starch solution was effective in reducing surface browning of sliced pears. Moreover, sliced pears treated with oxidized starch solution with addition of 0.1% sucralose were given an overall liking score which was slightly higher than that given to the other pears because of the sweetness of sucralose. In conclusion, 5% oxidized starch solution with addition of 0.1% sucralose was effective in reducing browning of sliced pears and in improving the taste of sliced pears.

• Korean Journal of Food Science and Technology
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• v.46 no.4
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• pp.418-424
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• 2014

High-acidity vinegar was manufactured using pear concentrate by fed-batch fermentation without additional nutrients, and the physicochemical properties and volatile components were investigated at different fermentation stages (Stages 1-4) and at various initial alcohol concentrations (IAC; 6-9%). The levels of reducing sugar, free amino acids, total phenolic content, total flavonoid content, and radical scavenging ability increased slightly during Stage 4 (high-acidity vinegar), which was affected by alcohol feeding. The contents of approximately 20 types of volatile compounds differed between the moderate- and high-acidity vinegar samples, as determined by solid-phase microextraction/gas chromatography-mass spectroscopy. The level of acetic acid in high-acidity vinegar increased according to the initial alcoholic content applied. The high-acidity vinegar produced by fed-batch culture at an IAC of 6-7% showed improved physicochemical and volatile properties as compared to the moderate-acidity vinegar.

• Korean Journal of Plant Tissue Culture
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• v.25 no.3
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• pp.159-163
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• 1998

In vitro shoot tip culture technique was established in pear (Pyrus pyrifolia 'Niitaka') as related to tree vigor, sampling time, and plant growth regulators and sucrose supplemented to medium. Shoot tips excised in June from the tree having medium-vigor developed good shoots. BA (1.0 and 2.0 mg/L) without NAA produced shoots suitable for proliferation, and NAA supplemented to medium resulted in poor shoot growth and excessive callus formation. BA of 2.0 mg/L combined with 0.01 mg/L NAA provided shoots suitable for rooting and sucrose of 30 g/L was recommended for proliferation medium. A fourth strength MS medium supplemented with 0.1 mg/L NAA produced plantlets in good quality of root number and root length.

• The Plant Pathology Journal
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• v.38 no.5
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• pp.482-489
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• 2022

Fire blight caused by Erwinia amylovora (Ea) is a devastating disease in apple and pear trees. Oxolinic acid (OA), a quinolone family antibiotic that inhibits DNA gyrase, has been employed to control fire blight in South Korea since 2015. The continuous use of this bactericide has resulted in the emergence of OA-resistant strains in bacterial pathogens in other countries. To investigate the occurrence of OA-resistant Ea strains in South Korea, we collected a total of 516 Ea isolates from diseased apple and pear trees in 2020-2021 and assessed their sensitivities to OA. We found that all isolates were susceptible to OA. To explore the possibility of emerging OA-resistant Ea by continuous application of OA, we exposed Ea stains to a range of OA concentrations and constructed OA-resistant mutant strains. Resistance was associated with mutations in the GyrA at codons 81 and 83, which result in glycine to cysteine and serine to arginine amino acid substitutions, respectively. The in vitro growth of the mutants in nutrient media and their virulence in immature apple fruits were lower than those of wild-type. Our results suggest that OA-resistance decreases the fitness of Ea. Future work should clarify the mechanisms by which OA-resistance decreases virulence of this plant pathogen. Continuous monitoring of OA-resistance in Ea is required to maintain the efficacy of this potent bactericide.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.4
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• pp.337-346
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• 2019

Land suitability assessments for agricultural crop production determine the suitability of an area in terms of crop yields. We employed the maximum limiting characteristic method (MLCM) and an analytic hierarchy process (AHP) to assess land suitability for Pears (Pyrus) in all Korean provinces (Dos). In general, suitability grades according to the MLCM were much lower than those according to the AHP. The MLCM determined that suitable areas (S1, S2, and S3) exist on 19.55% of the land, whereas 99.08% of the land was classified as suitable by the AHP. Based on information on pear farms in each Korean province in 5 years (1982, 1987, 1992, 1997, 2002, and 2007), the proportion of suitable land area according to the MLCM in each province as compared to all suitable areas was closer to the proportion of areas covered by pear farms in the 5 years in each province and also to the proportion of pear farm areas in 2007 in each province. Based on the assumption that if a province has more suitable areas for pears, more pears will be cultivated in that province, the results of the MLCM can be regarded as more accurate than those of the AHP.

• Korean Journal of Food Science and Technology
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• v.47 no.2
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• pp.254-260
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• 2015

The effect of the extraction solvent on the physiological properties of the peel of the Korean pear (Pyrus pyrifolia cv. Niitaka) was evaluated. The total phenol content was highest in the 80%(wt) methanol extract, whereas flavonoid content was highest in the 80% ethanol extract. The antioxidant activities of the extracts were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging abilities, and their reducing power. The water and 80% methanol extracts of the pear peel had highest DPPH and ABTS radical scavenging activities, and reducing power, respectively. The inhibition of ${\alpha}$-glucosidase was highest in the 80% methanol extract, and alcohol dehydrogenase activity was highest in the water extract. All three extracts had similar antimicrobial activity. Because water, 80% ethanol, and 80% methanol extracts exhibited high activities in different assays of physiological properties, each solvent could be used for specific purposes.