• Journal of Labour Economics
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• v.24 no.3
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• pp.1-12
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• 2001

Seoul/Kyungki-born workers have higher wages than other regions-born workers. In order to determine whether this difference is due to taste or statistical discrimination, an econometric model is suggested and a test is done with it. According to the test, the hypothesis that the difference is wholly due to taste discrimination is rejected: a part of the difference is due to statistical discrimination. Since statistical discrimination in this paper comes out in the process of a worker's wage being determined according to his productivity, it is no problem for the government to intervene in.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2000.10a
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• pp.64-64
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• 2000

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2002.05a
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• pp.117-117
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• 2002

• Research in Plant Disease
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• v.10 no.1
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• pp.39-43
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• 2004

Recent occurrence of virus diseases on watermelon plants cultivated in Jeonnam province was investigated from 1998 to 2002. While virus diseases were severely occurred on watermelon cultivated in green house in 1998, those of open field were severer than in green house since 2000. When 128 samples collected from different fields were examined by electron microscopy, 87.8％ of the samples contained rod-shaped or filamentous virus particles. RT-PCR analysis of the samples revealed that Cucumber green mottle mosaic virus (CGMMV) was only detected from collected samples at May. Watermelon mosaic virus (WMV) was most frequently found and CGMMV and Zucchini yellow mosaic virus (ZYMV) were slightly at June and July. However Cucumber mosaic virus (CMV) and Papaya ringspot virus (PRSV) have not been detected.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.52-52
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• 2019

산채는 사람에 의하여 개량 육성되어 논밭에서 재배하고 있는 농작물과 달리 자연 그대로 산야에서 자생하는 식물 중 식용으로 가능한 것을 말한다. 우리나라 산야에는 480종의 식물이 식용으로 이용될 수 있다고 하나 현재 전국에서 재배하고 있는 작목은 36종으로 추정되며, 앞으로도 80여 종이 개배 가능한 작물로 추정된다. 산채류의 이용형태별 생산가능시기는 3~5월의 생채 생산과 6~7월의 건채 생산으로 소비자의 기호에 부합하는 신선 생채의 소비한계는 제한되어 있기 때문에 재배유형별 생채 수량검정을 통해 수확시기 연장 및 재배품목을 다양화 시킬 필요 있다. 이에 본 시험은 산채류 재배유형별 수확기간을 구명하고자 표고 500 m의 전북 남원시 허브산채시험장에서 2018년 5월 말 갯기름나물 등 15 종을 노지와 하우스에 정식하여 각 작물의 생육특성, 수확한계기 등을 조사하였다. 1년차 지상부 생육특성을 조사한 결과 참취, 개미취, 섬쑥부쟁이, 질경이, 갯기름나물, 두메부추, 돌단풍, 참당귀의 경우 초장, 엽장 등은 노지보다 하우스에서 높은 편이었고 생존율은 비슷하거나 하우스에서 더 높은 경향을 보였다. 우산나물, 단풍취의 생존율은 하우스에서 더 높았으나 생육 초기 엽소현상으로 인해 1년차 생육은 노지, 하우스에서 둘 다 저조하였고 곤달비, 어수리, 곰취, 눈개승마의 경우 노지에서는 7월 중순이후 지상부가 전부 고사하였으나 하우스에서는 생존율이 상대적으로 양호하여 11월 상순까지 후기 생육을 하였다. 2년차 산채류 출현기 조사한 결과 하우스 재배에서 산마늘이 2월 중순으로 가장 빨랐고 갯기름나물, 곤달비 등 10종이 2월 하순에 출현하였으며 참당귀 3월 상순, 단풍취 및 우산나물 3월 중순, 돌단풍이 가장 늦은 3월 하순에 출연하였다. 생체수확 시기는 갯기름나물, 눈개승마, 산마늘, 두메부추, 섬쑥부쟁이는 3월 중순부터 가능했고 곤달비 등 12개종은 3월 하순, 우산나물은 4월 상순, 돌단풍은 4월 중순으로 가장 늦게 생체수확이 가능했다. 노지 재배의 경우 산마늘과 눈개승마가 3월 중순으로 가장 빨랐고 갯기름나물 등 10종이 3월 하순에 출현하였으며 돌단풍, 참당귀, 단풍취가 4월 상순으로 가장 늦은 출연을 보였다. 생체수확 시기는 눈개승마와 산마늘이 4월 상순으로 가장 빨랐으며 갯기름나물 등 10종이 4월 중순부터 가능했고 돌단풍, 참당귀, 단풍취가 4월 하순으로 가장 늦었다. 수확한계기 조사 결과 눈개승마, 산마늘, 우산나물은 하우스 및 노지재배에서 20일정도로 가장 짧았으며 그 외 작물들은 계속적으로 수확이 가능하였으나 6월 상순 이후에는 품질이 나빠져 생체상품으로서 가치가 없었다.

• Korean journal of applied entomology
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• v.42 no.2
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• pp.153-157
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• 2003

This experiment was conducted to investigate control effect of Spodoptera litura using nucleopolyhedrovirus in chrysanthemum seedlings of open field and plastic house. Values of LT$_{50}$ of treatment 1.0$\times$10$^{6.8}$ PIBs/ml were 6.2-5.1 days in open field and 6.9-5.4 days in plastic house. Values of LT$_{50}$ and LT$_{95}$ were shorter in open field than in plastic house. Cumulative mortality was 100% in 1.0$\times$10$^{7.8}$ PIBs/ml and also higher in open field than in plastic house. In chrysanthemum field, organic synthetic insecticide (endosulfan EC) killed S. litura larvae in 2 days after application. Motality of S. litura larva inoculated with S. litura nucleopolyhedrovirus (SINPV) 1.0$\times$10$^{6.8}$ PIBs/ml was found out from 4 days after application and maintained during 14 days. Protection values of with SINPV 1.0$\times$10$^{8}$ PIBs/ml after 16 days were 94.0% and 89.4% in open field and plastic house, respectively, and those of endosulfan 350 ppm were 91.4% and 88.6%, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.1
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• pp.4-11
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• 2007

There have been increasing concerns about decreasing crop productivity due to salt accumulation in greenhouse soils. The objective of the study was to investigate the impact of rice straw and woodchip application to a salt accumulated greenhouse soil on crop productivity and soil quality. The application of rice straw (RS) and woodchip (W) increased tomato yield and decreased blossom-end rot, and increased yield of Chinese cabbage compared with standard recommended fertilization ($204-103-122kg\;ha^{-1}\;N-P_2O_5-K_2O$ for tomato and $222-64-110kg\;ha^{-1}\;N-P_2O_5-K_2O$ for Chinese cabbage), while less soil residual nitrate, phosphatephosphorus, and potassium. In addition to the organic material application, fertilization reduction based on soil testing may also contribute to relatively low level of soil residual nutrients. Application of the organic material reduced soil bulk density presumably because of improved soil aggregation and structure, and increased biomass C and dehydrogenase activity. In comparison to rice straw, woodchip application resulted in higher crop yield, less amount of soil residual nitrate and lower soil EC, and greater biomass and dehydrogenase activity. The results obtained in this study indicateshowed that woodchip amendment along with reduced fertilization based on soil testing can be one of essential management practices for salt accumulated greenhouse soils.

• Korean Journal of Agricultural Science
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• v.4 no.2
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• pp.126-140
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• 1977

Present studies were carried out for breeding cold resistant clones of Citrus, improving overwintering techniques of Citrus in Jeju island as well as other southern region, Result obtained were as follows 1. In the vinyl house covered with two sheets of straw mat, 12 indivuals were found as non-injury and 15 were slightly injured by leaf freeging test at $-9^{\circ}C$ for 2 hours treatment. 2. In the condition of vinyl house covered with straw mat and viny film mulching and heat-in by sun-light, the inside temperature of vinyl house were not lowered below $-3^{\circ}C$ and the ground temperatura in vinyl house keeps above $0^{\circ}C$ during winter though outdoor temperature were lower by $-15^{\circ}C$(Daejeon area). 3. The vinyl tunnel inside the vinyl house and vinyl film mulching on ground position showed greater effectiveness for preventing heat loss from house but there were no significant difference between the color of vinyl film covered the tunnel. 4. In the vertical distribution of maximum temperature in vinyl house, the upper space was slightly higher than the lower position at high temperature condition, while minimum temperature was distributed as higher as the middle position, ground surface and upper position in order at low temperature condition 5. In the horizontal distribution of temperature in vinyl house, ground and surface-temperature of north side was lower than the other sides, and citrus planted within 30cm from north side wall died by cold injury and in the other side near wall appeared slight symptom of cold injury. 6. The insulating trench ($30{\times}30{\times}30cm$) packed with straw bundle installed under north wall might be effective to prevent heat loss of ground temperature. 7. In cloudy and snowy day, the temperature difference between indoor and outdoor were less, and the indoor temperature were maintained highly during night due to the effect of prevention of heat loss. 8. The highest temperature in a day was observed at about P.M. 3 both inside and outside of vinyl house and the lowest temperature was observed at about A.M. 6. The difference between the highest and lowest temperature of indoor in a sunny day was $19^{\circ}C$, compared with $9^{\circ}C$ on a cloudy or snowy day in late November. Especially, lowering of temperature in a snowy day was so less that the curve of temperature change was comparatively constant, 9. If the effective methods of citrus cultivation in vinyl house with improved clone such as hardiness. semi-dwarf and spur type are applied, it might be possible to cultivate the citrus tree safely in Jeju island as well as other southern rejion and to magnity the cultivation of citrus tree.

• Korean Journal of Plant Resources
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• v.24 no.5
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• pp.622-627
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• 2011

This study was designed to investigate the possible role of 10 green manure crop extracts in antimicrobial activity against potato common scab (Streptomyces scabiei). Ten green manure crops were extracted with hexane, ether, ethylacetate, methanol and water. The DPPH radical scavenging activity of ether, methanol and water was higher than those of hexane and ethylacetate fractions. The fractions of methanol, ethylacetate, ether and water showed antimicrobial activity against Streptomyces scabiei from the concentration of 0.25 mg/mL. Methanol fraction of Sorghum showed the highest antimicrobial activity against this microorganism. This result suggests the sorghum extract was the best as good green manure crop with antimicrobial activity against Streptomyces scabiei.

• Journal of Korea Port Economic Association
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• v.30 no.2
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• pp.133-143
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• 2014

The paper uses a panel gravity model to analyse the determinants of export via Gwangyang port for the period from 2000-2012. The gravity model includes export via Gwangyang port, GDP and population of trading partners, the distances between Korea and its partners, and Korea-ASEAN FTA dummy. Hausman test shows up which one is exactly appropriate between random effect estimation and fixed effect estimation to use panel dataset. It depends on whether or not existence or nonexistence of the correlation between unobserved omitted factors and variables. Fixed effect estimation is suitable for this paper by the rejection of null hypothesis. An Empirical analysis of this paper shows GDP influences positive effects and distance influences negative effects to Gwangyang port trading partners. In addition, the results strongly supported the effects of Korea-ASEAN FTA on the growth of Gwangyang port export.