• Korean Journal of Agricultural Science
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• v.16 no.2
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• pp.225-238
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• 1989

These studies were conducted to investigate the extraction, purification and characterization of oriental pear (Niitaka. Pyrus pyrifolia Nak.) protease, and the results obtained were as follows: 1. Oriental pear protease was effectively extracted by the method of homogenizing pear pulp with 0.7 volume of 0.1M-sodium phosphate buffer, pH 6.5 containing 5mM-cysteine, 40mM-2-mercaptoethanol and 2mM-EDTA at 10,000 rpm for 5 min. 2. The protease was purified by ammonium sulfate fractionation, Sephadex G-100 filtration and DEAE-Sephadex A-50 column chromatography, and the purified enzyme gave a single protein band on polyacrylamide gel electrophoresis. 3. The specific activity of purified enzyme was 29.65 unit/mg protein and the yield was 7.22%. 4. The moecular weight of the protease was estimated to be about 51,000 by SDS-polyacrylamide gel electrophoresis, and the enzyme had Km value of 54.5 mg/ml for casein. 5. The purified enzyme had a maximum activity at pH 6.0 and $50^{\circ}C$, and was stable from pH 5.5-6.5 and at temperatures below $50^{\circ}C$ 6. Casein was a better substrate for this protease compared to hemoglobin. 7. The enzyme activity was markedly inhibited by p-chloromercuribenzoic acid and heavy metal salts such as $HgCl_2$ and $MnSO_4$ also considerably inhibited the enzyme activity.

• Journal of Plant Biotechnology
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• v.42 no.1
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• pp.25-33
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• 2015

A PyrcpPR-10 gene with differentially expressed was isolated by using the suppression subtractive hybridization assay between '93-3-98' (highly resistant against scab caused by Venturia nashicola) and 'Sweat Skin'(highly susceptible) and analyzed the expression pattern according to organs and cultivars. The full length of PyrcpPR-10 was cloned as 743bp with 480bp's ORP, and was determined to encode a protein of 159 amino acid residues. On analyzing PyrcpPR-10 gene sequence compared with resistant and susceptible cultivars, 'Hwangsilri' (resistant), 'Gamcheonbae' (moderately resistant), 'Wonhwang' (moderately susceptible), 'Niitaka' (highly susceptible), and 'Sweat Skin' (highly susceptible) had identical gene sequence but 'Bartlett' (highly resistant) showed partly different sequences. The deduced amino acid sequence showed 64 ~ 98% homology and had the GXGGXG motif to known amino acid of other plants PR-10 by the BLAST X analysis. Among several organs or tissues, petal was showed highest expression level of PyrcpPR-10 gene followed by leaf, floral axis, bud, and bark. The expression level of PyrcpPR-10 gene was dramatically increased at 24 hr after inoculation in all cultivars and also up-regulated in accordance with resistant degree of cultivars. While resistant cultivars ('Bartlett', '93-3-98', and 'Hwangsilri') induced relatively high expression level of PyrcpPR-10 gene, susceptible cultivars ('Niitaka', and 'Sweat Skin') showed low expression level. PyrcpPR-10 gene is assumed that it is directly connected with defense mechanisms to pear scab.

• Horticultural Science & Technology
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• v.32 no.1
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• pp.77-83
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• 2014

To improve the breeding efficiency of oriental pear, the inheritance of major fruit traits were analyzed using 4,035 seedlings of 15 cross combinations combined with 13 cultivars. Yearly variation of parental cultivars, broad-sense heritability of the traits, and frequency of seedlings with commercially acceptable characteristics by the mid-parent values were studied. Despite the heritabilities of traits related with pear the fruit texture were different depending on cross combination, the average narrow-sense heritability ($h^2$) for firmness, flesh hardness, flesh density and grit were over 0.6, a relatively high value. However fruit firmness showed different heritability among the cross combination and its value of cross combination between 'Niitaka' and 'Choju' was very low as 0.11. Positive correlation was not observed on fresh hardness, fresh density and grit but observed on firmness between mid-parent value and average value of offspring. Regression of offspring on firmness, fresh hardness, fresh density and grit between mid-parent value and average value of offspring were 0.778, 0.343, -0.273, 0.313, respectively. Frequency distributions of fruit texture in 15 cross combinations of pear seedling was influenced by parental characteristics. When fruit firmness was estimated as low, low ${\times}$ high and high ${\times}$ high values in parental fruits, firmness in their offspring exhibited low, medium and high, respectively. In addition, when parental grit by sensory evaluation were light ${\times}$ light and light-medium ${\times}$ medium-heavy, most of offsprings showed light and medium grit, respectively.

• Korean Journal of Food Science and Technology
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• v.48 no.1
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• pp.59-65
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• 2016

This study was carried out to investigate the total polyphenols, antioxidant activities, and melanin synthesis inhibition of several pear cultivars (Pyruspyrifolia). The total polypenolic content of five pear cultivars was high in the unripe developmental stage. Total polyphenolic content of the Chuwhangbae cultivar extract was higher than that of other pear cultivars regardless of the developmental stage. However, the total flavonoid content did not differ between cultivars or developmental stages. The phenolic compound, arbutin has an inhibitory effect on melanogenesis. Arbutin levels in pear cultivars declined as the fruit matured. The free radical scavenging activity of the extract also decreased as the fruit ripened. In B16F10 mouse melanoma cells, most of the cultivar extracts inhibited melanin synthesis by about 50% at a $100{\mu}g{\cdot}mL^{-1}$ concentration, except in the Gamcheonbae extract until 90 days after full bloom. We have confirmed that the extract of pear cultivars have antioxidant activity and skin-whitening effects.

• Journal of Bio-Environment Control
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• v.15 no.1
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• pp.84-90
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• 2006

This study was conducted to anticipate nitrate reduction state in tree through measurement of nitrate reductase activity (NRA) and investigate the effect of nitrogen concentrations (100, 200, 400, and 600 $mg\;L^{-1}$) on growth, the nitrogen content of various tissue, and NRA of pear (Pyrus pyrifolia cv. Niitaka) seedlings in sand culture. Nutrient solutions used in this experiment were adjusted to pH 6.5 and fixed the ratio of ammonium and nitrate to 1:3 and trickle-irrigated 3 times a day. Tree height and dry weight of various organs in seedlings were higher in low nitrogen concentration (100 and 200 $mg\;L^{-1}$) than in high nitrogen concentration (400 and 600 $mg\;L^{-1}$). The shoot growth in 600 $mg\;L^{-1}$ was extremely poor by nitrogen over supply. Increasing the nitrogen concentration, the concentration of nitrate-N in leaves and roots were insignificantly changed but that of stems increased. The accumulation of total and reduced nitrogen in all organs with increasing concentrations of nitrogen supply were increased at 30 days after treatment but those of all organs at 60 and 90 days after treatment were highest in 600 $mg\;L^{-1}$, whereas there were no significant changes among other nitrogen concentration. The in vivo (${+NO_3}^-$) NRA of all organs did not relate to nitrogen concentration but the in vivo (${-NO_3}^-$) NRA of leaves except roots increased with increasing the nitrogen concentration. Therefore, the proper nitrogen concentration to promote growth and nitrate reduction of pear tree was 200 $mg\;L^{-1}$.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1999.03a
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• pp.163-167
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• 1999

사회와 생활수준의 발달로 인간은 자연환경하에서 생활보다 인공적 환경하에서의 생활이 증가하게 되었다. 따라서 인간은 쾌적한 생활공간을 요구하게 되었고 이를 위한 온열환경에 대한 연구가 진행되어져 왔다. 이러한 생활공간에서의 쾌적한 온열환경에 영향을 주는 물리적 요인으로는 온도와 습도 그리고 기류 등이 있다. 또한 온열환경에 대한 인간의 감성적 측면도 쾌적한 온열환경을 결정하는데 중요한 역할을 한다. 본 연구에서는 겨울철 대류난방시 인간에게 가장 쾌적한 환경을 제시할 수 있는 기류 속도의 범위를 찾고, 이를 평가하는데 객관적인 지표를 설정하기 위해 온도에 따른 기류조건을 제시하고, HRV 분석을 통하여 인체의 자율신경계의 변화를 관찰하였다. 실험결과 18$^{\circ}C$, 21$^{\circ}C$, 24$^{\circ}C$ 각각의 온도에서 draft를 초래하지 않는 0.15m/sec의 기류속도일 때 가장 높은 MF/(LF+HF) 값을 보여 쾌적한 기류조건으로 나타났고 이는 쾌불쾌감신고(CSV)와 동일한 결과를 나타내었다. 이러한 심전도 신호를 통한 HRV 분석은 기류조건에 따른 온열쾌적성의 평가에도 객관적이고 신뢰성 있는 지표로 제시될 수 있을 것이다. 또한 다른 환경하에서의 감성평가 척도로도 이용될 수 있을 것이라고 생각되어진다.

• Korea journal of population studies
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• v.23 no.1
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• pp.5-29
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• 2000

도시화 및 산업화는 가족의 애정기능 증대, 친족관계 약화, 공사영역분리, 여성의 교육수준 향상 및 취업기회 증가, 부부관계의 평등성 추구 등을 통해 이혼을 증가시키는 요인으로 알려져 왔다. 혼인·이혼신고 자료와 인구주택총조사 자료를 활용하여 1970년∼1995년 동안 발생한 한국의 성별, 연령별, 시도별, 교육수준별 이혼율을 비교하였다. 이혼수준을 측정하기 위하여 조이혼율, 일반이혼율, 연령별이혼율, 연령표준화 이혼을 전체인구와 유배우인구를 대상으로 각각 산출하였고, 각종 이혼력 지표의 특성을 논의하였다. 1970년∼1995년 동안 이혼율이 3배 증가하였으며, 1995년 현재 유배우인구 천 명당 3.2건의 이혼이 발생하였다. 동기간 동안 24세 이하 연령층의 이혼율이 가장 높았고, 전 연령층에 걸쳐 빠른 속도로 이혼율이 증가하였는데, 증년층의 이혼율 증가 속도가 가장 빨랐고, 남성보다는 여성의 상대적 이혼율 증가 정도가 더 빨랐다. 시도별 이혼율은 전연령층에 걸쳐 서울, 부산, 인천, 대전, 경기, 제주도가 높았고, 강원도와 전라북도 25∼34세 연령층의 이혼율이 높았다. 교육수준별 이혼율이 남자는 초등학교 졸업집단에서, 여자는 고등학교 졸업 집단에서 가장 높았고, 남자는 대졸 이상 집단, 여자는 무학 집단에서 가장 낮게 나타났다.

• Korean Journal of Organic Agriculture
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• v.18 no.3
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• pp.363-375
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• 2010

Sustainable farming systems have remarkably increased in Korea due to the increase of environmental concerns caused by the conventional systems. This study was performed on eight-year-old 'Niitaka' pear tree s to investigate the effects of different organic fertilizers on soil chemical and microbial properties and leaf and bud developments. Treatment and applications included 10 kg of rice bran (RB), 10 kg of coffee bran compost (CBC), 10 kg of Chitin incubated compost (Micro keeper$keeper^{(R)}$, CIC), and 30 kg of the mixture of the RB, CBC, and CIC (RCC). Control received 60 g of NPK (16-11-12) chemical fertilizer. The organic fertilizers increased organic matter, nutrient concentrations such as P, K, Ca, and Mg, and microbial biomass in soils compared to the control. RCC had the greatest specific leaf weight (SLW), and the other treatments did not have a significant difference for the SL W. Leaf P and K concentrations were different among the treatments, but they were not affected by the amounts of the soil nutrients. No differences were observed in the leaf Ca and Mg concentrations in the treatments. Organic fertilizers had greater chlorophyll contents than the control but had similar flower bud characteristics to the control.

• Horticultural Science & Technology
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• v.34 no.6
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• pp.959-965
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• 2016

In 1994, a new cultivar 'Joyskin' was created from a cross between the cultivars 'Whangkeumbae' and 'Waseaka' at the Pear Research Institute of the National Institute of Horticultural and Herbal Science, Rural Development Administration. In 2006, the 'Joyskin' was selected from among the 317 seedlings resulting from the cross for its skin and taste qualities. Regional adaptation tests were conducted in nine regions and in ten experimental plots from 2006 to 2011. The cultivar was named in 2011. 'Joyskin' showed a vigorous growth habit and semi-spread characteristics similar to 'Whangkeumbae'. The average full bloom date for 'Joyskin' was April 21st, which was also similar to 'Whangkeumbae'. The optimum fruit ripening time was September 6-8th, which was six or eight days earlier than 'Whangkeumbae'. The fruit was round in shape and the skin was a golden yellow color at maturity. The average fruit weight was 320 g and the flesh firmness was $2.5kg/8mm{\varphi}$. The firmness of the fruit skin determined by a blade-type plunger of texture analyzer was 22.9 N, which was significantly different from that of 'Whangkeumbae' 29.9N. Stone cell analysis of 'Joyskin' by phloroglucinol-HCl, showed that 'Joyskin' stone cells were small in size and few in numbers cpmpared to those of cultivars of was 'Manpungbae', 'Niitaka', and 'Whangkeumbae'. The patent application for 'Joyskin' was submitted in April, 2012 (Grant No. 2012-337). In 2016, 'Joyskin' (Grant No. 5895) was registered as a separate record, with uniformity and stability per Korean Seed Industry Law.

• Horticultural Science & Technology
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• v.31 no.6
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• pp.828-832
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• 2013

To report country-specific carbon and nitrogen stocks data in a pear orchard by Tier 3 approach of 2006 IPCC guidelines for national greenhouse gas inventories, an experimental pear orchard field of the Pear Research Station, National Institute of Horticultural & Herbal Science, Rural Development Administration, Naju, Korea ($35^{\circ}01^{\prime}27.70N$, $126^{\circ}44^{\prime}53.50^{\prime\prime}E$, 6 m altitude), where 15-year-old 'Niitaka' pear (Pyrus pyrifolia Nakai cv. Niitaka) trees were planted at a $5.0m{\times}3.0m$ spacing on a Tatura trellis system, was chosen to assess the total amount of carbon and nitrogen stocks stored in the trees and orchard soil profiles. At the sampling time (August 2012), three trees were uprooted, and separated into six fractions: trunk, main branches, lateral branches (including shoots), leaves, fruits, and roots. Soil samples were collected from 0 to 0.6 m depth at 0.1 m intervals at 0.5 m from the trunk. Dry mass per tree was 4.7 kg for trunk, 13.3 kg for main branches, 13.9 kg for lateral branches, 3.7 kg for leaves, 6.7 kg for fruits, and 14.1 kg for roots. Amounts of C and N per tree were respectively 2.3 and 0.02 kg for trunk, 6.4 and 0.07 kg for main branches, 6.4 and 0.09 kg for lateral branches, 6.5 and 0.07 kg for roots, 1.7 and 0.07 kg for leaves, and 3.2 and 0.03 kg for fruits. Carbon and nitrogen stocks stored between the soil surface and a depth of 60 cm were 138.29 and $13.31Mg{\cdot}ha^{-1}$, respectively, while those contained in pear trees were 17.66 and $0.23Mg{\cdot}ha^{-1}$ based on a tree density of 667 $trees{\cdot}ha^{-1}$. Overall, carbon and nitrogen stocks per hectare stored in a pear orchard were 155.95 and 13.54 Mg, respectively.