• Korean Journal of Organic Agriculture
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• v.21 no.4
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• pp.669-684
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• 2013

This study was investigated to evaluate the effects of biodiversity and pest insect occurrence by soil surface management methods such as green manure crop, grass planting and clean-tilled crops on persimmon orchards. Green manure crop pests was investigated 7 species including Hypera postica, Laodephax striatellus, Megoura crassicauda, Aphis craccivora, Nephotettix cincticeps, Liriomyza sp., black spot and the most dangerous pest was H. postica but it did not damaged persimmon tree. Amount of pests and natural enemies dwelling soil covering plant was not difference between organic farming (hairy vetch planting) and conventional farming (natural weed). Homona magnanima occurred three times a year but it rarely damaged leaf of persimmon. Total adult moth catched by pheromone trap was 1,261 organic farm, 1,003 conventional farm and 621 clean-tilled farm. Grapholita molesta occurred four times a year but it also rarely damaged twig of persimmon. Number of collected invertebrate species and individuals on soil sample was follow as : 838 individuals of 22 species at organic farm, 421 individuals of 17 species at conventional farm and 381 individuals of 15 species at clean-tilled farm. The richness index was lined up by organic farm 3.12> conventional farm 2.65> clean-tilled farm 2.36.

• KOREAN POULTRY JOURNAL
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• v.14 s.149
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• pp.75-80
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• 1982

종계가 낳은 알이 모두 종란은 아니다. 수정율, 부화율이 높고, 품질 좋은 초생추를 생산할 수 있는 종란만이 종란이다. 종란을 취급하는데 있어 좀 더 세심한 주의를 기울일 필요가 있다.

• KOREAN POULTRY JOURNAL
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• v.19 no.8 s.214
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• pp.108-114
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• 1987

작업능률을 올릴 수 있고 인원의 효율적 관리를 위해서, 그리고 고른품질이 유지되고 오염되지 않은 초생추 생산을 위해 이제 부화장 건축은 과학적이고 통계적 바탕위에 시행되어야 한다. 적어도 15년에서 20년은 넉넉히 견딜 수 있게 부화장은 설계되고, 사용하는 데 부족함이 없이 부화기는 선택되어야 한다.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.12
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• pp.792-800
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• 2012

The study was performed to simulate the reduction efficiency of suspended solids (SS) for cultivated land located at riverine area at the Namhan River and the Bukhan River watershed sites (site A, B, C) under the rainfall conditions using HUFF & SCS UH-based VFS Design module of Web GIS-based VFSMOD System. The study indicates that the field 5% sloped, located at Bukhan River watershed (site A), requires at least 0.5 m width of Vegetative Filter Strip (VFS) to reduce 70% of SS while the field 10% sloped requires the at least 1.0~1.5 m width of VFS to reduce 70% SS, under the condition 106.2 mm of rainfall event and bell pepper or corn of crops. Against the conditions 95.1 mm of rainfall event and sweet potato or soy bean of crops, the field 5% sloped, located at Namhan River watershed (site B) requires at least 0.5 m width of VFS to reduce 70% of SS while the field 10% sloped requires at least 1.0 m width of VFS to reduce 50% SS. The crops sweet potato and soy bean are cultivated in the site C, located at Namhan River watershed, 1 m of VFS is capable of 64.0% and 62.0% of SS reduction against 102.6 mm and 151.2 mm rainfall conditions respectively, for the 5% sloped field. The result supports that VFS is one of most potential methods to reduce SS from cultivated area, which is environment-friendly hydrologic structure. The VFS design, however, needs to be simulated before its installation in the field, the simulation needs to consider not only various characteristics of the field but also different conditions affecting the VFS, using a model capable to consider a lot of factors.

• The Journal of the Petrological Society of Korea
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• v.1 no.2
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• pp.132-137
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• 1992

Review of metamorphic terms and rock names from various published articles in Korea reveals that they have often been misused and they may lead to a faulty results in the interpretations of the geologic mass. Their usage can be classified into several groups. A few simple rules are proposed for use in naming metamorphic rocks. The new rock names make by the proposed rules are listed as table with old names.

• KOREAN POULTRY JOURNAL
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• s.112
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• pp.42-47
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• 1979

1979년 1월 15일 현재, 양계인은 울고 있다. 육계시세의 폭락, 육용초생추의 덤핑난무, 사료파동, 육류수입개방과 축산정책에 대한 절망적인 회의, 질병만연과 기타의 제반악조건-등! 왜 이렇게 웃고 있으며 양계인은 어떻게 해야 웃을 수 있을 것인가?

• Korean journal of applied entomology
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• v.61 no.1
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• pp.255-266
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• 2022

This study was conducted to examine the effects of grass vegetation (W: manual weeding, NW: herbicide sprays) and pyrethroid spray (P: pyrethroid spray, NP: no pyrethroid spray) on the population dynamics of Panonychus citri and natural enemies in citrus orchards. Two essential hypothesis were made to test the population dynamics: 1) weed planting promotes natural enemies by offering habitat and alternative food sources, resulting in the reduction of P. citri populations, and 2) pyrethroid spray removes natural enemies by its non-selective toxicity, resulting in the increasement of P. citri populations. The observed natural enemy populations (mainly Phytoseiids and Agistemus sp.) were not different largely from the expected values in the hypothesis, which assumes more abundant natural enemies in weeds and no pyrethroid plots. Although some discrepancy was occurred in NW+NP and W+NP plots in 2011, the observed values were almost same with expected values in 2012. In overall, pesticide effect was strongly significant and pyrthroids removed largely natural enemies. Although habitat (weeds) effect showed a conflict result, natural enemy population increased in plots allowing weed growth, when considering the increased autumn population relatively compared to that of spring-summer population. The decreased abnormal P. citri populations in pyrethroid plots could be explained under the assumption of a strong repellent behavior of P. citri to the pyrethroids.

• Journal of Korean Society of Forest Science
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• v.40 no.1
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• pp.70-74
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• 1978

The aims of this study was to elucidate the correlation between cotyledon numbers and seedling growth and some other traits of Pinus koraiensis. The results are summurized as follows; 1. A highly significant correlations between numbers of coty ledons and juvenile needles was found but no significances between cotyledon numbers and juvenile needle length, width and stomata row numbers. 2. The accessory resin canals did not begin to appear before June but began to appear only small numbers of seedling after July. It was observed that the number of accessory resin canals of juvenile leaves at various growing stages were not related with the number of cotyledons. 3. In the case of adult leaves, there was a significant difference in the number of leaves and the number of cotyledons, but no significant difference between the number of cotyledons and needle length, needle width and stomata row. 4. There were significant differences in the number of cotyledons and top height growth, and root caliper growth among individuals and due to ages. 5. Seedlings with more than 12 cotyledons showed better growth than those with 9 to 11 cotyledons.

• The Journal of the Acoustical Society of Korea
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• v.42 no.3
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• pp.243-249
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• 2023

The occurrence of cavitation on the propeller is directly linked to the naval ship's survivability, and it is necessary to design a propeller shape that delays the cavitation inception. However, the propeller cavitation can occur under various operating conditions, thus it is important to identify whether the propeller cavitation exists during operation as well as in the design phase. To this end, it is necessary to use noise or vibration signals on board to monitor the cavitation inception. In this study, a hydrophone and an accelerometer were installed on the ship hull right above the propeller to compare the performance of analyzing cavitation inception between acoustic and vibration signals. Also, a high speed camera was used to visually observe the occurrence of cavitation through an observation window. The measured results showed that the spectral shapes between acoustic and vibration signals were different, but the level increases at each frequency band and the overall level of the frequency band from 1 kHz to 10 kHz showed a similar tendency. The Detection of Envelope Modulation On Noise (DEMON) analysis also showed similar results for both acoustic and vibration signals, confirming that both hydrophones and accelerometers can be utilized in the analysis of cavitation inception.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.3
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• pp.127-130
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• 1987

The Cavitation inception in oil hydraulic pipeline was investigated experimentally and numerically. In the experiment, negative pressures below -1 MPa (absolute pressure) were measured, associated with the transient flows in oil hydraulic pipeline. These experimental results show that the common hydraulic oil in the experimental pipeline withstands large tensions. The growth of a spherical bubble in a infinite volume of viscous compressible fluid due to a stepwise pressure drop was investigated to obtain the critical bubble radius. The calculated value of the critical bubble radius corresponding to the negative pressure measured in the experiment is so small that the premised condition about the bubble shape in the analysis is unsatisfactory. The physical significance of this calculated result implies the fact that there hardly exist free bubbles which can act as cavitation nuclei in the experimental pipeline.