• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.2
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• pp.13-20
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• 1990

The interaction of the flows induced by stator blades with a ship-like wake is discussed to obtain the flow components of each with and without radial shear. The flow induced by stator blades is modeled by lifting line theory and the shear is taken to be provided by the radial gradient of the peripheral mean axial flow approximated by a logarithmic function of radius for a class of vessels. And the theory is based on the linearized Euler equations in the absence of viscosity. The results show that shear effects are relatively large at inner radii and the distribution of blade pitch angles is most effective in reducing non-uniformity.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.447-450
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• 2006

최근 국내외에서 재래식 폭탄의 정확도와 사거리를 향상시킨 정밀 유도 무기에 관한 연구가 활발하게 진행 중에 있다. 국내에서는 국방과학연구소의 주도로 재래식 폭탄에 GAK(GPS Adapter Kit)를 장착하는 연구가 진행 중이다. GAK는 GPS/INS 복합 항법 모듈을 내장한 사거리 연장 유도 키트의 일종으로 폭탄이 투하되면 접혀 있던 날개가 전개되고 이후 날개의 플래퍼론을 구동하여 유도 조종을 수행한다. 복합 항법 모듈은 상용의 MEMS IMU, 내장형 GPS 수신기 및 항법 컴퓨터와 실시간 운영 체제에서 구동되는 항법 소프트웨어로 구성된다. 본 논문에서는 복합 항법 모듈의 비행 시험 결과를 제시하였다. 시험 결과 항법 모듈이 실시간으로 정상적인 동작을 수행하였으며 GPS 유도 폭탄의 유도 조종에 적합한 항법 정보를 제공하였음을 확인하였다.

• The Korean Journal of Pesticide Science
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• v.14 no.2
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• pp.164-169
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• 2010

Methyl (E,E,Z)-2,4,6-decatrienoate is the aggregation pheromone of brown-winged stink bug Plautia stali (Hemiptera: Pentatomidae). Attractiveness of the pheromone synthesized in Korea was compared with that of synthesized in Japan in the field. A lure filled with hexane was used as a control treatment. Catches in trap baited with Korean pheromone was significantly higher than that baited with Japanese one only in one orchard out of three sweet persimmon orchards in 2008. However there was no difference in trap catches between Korean and Japanese pheromones at three sites in 2009. Gas chromatography analysis showed that the components of both pheromones were not different each other. Monitoring of P. stali seasonal fluctuation using Korean pheromone showed that the bugs were most captured in August, 2008 and in September, 2009.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.1
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• pp.30-36
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• 1999

A surface panel method for the analysis of ducted propellers in both uniform and non-uniform onset inflow is developed. A low order, perturbation potential based panel method with an efficient numerical Kutta condition is used. The boundary surface is discretized with hyperboloidal panels and the boundary condition is applied at the panel centroids. The unsteady analysis is based on a time-step algorithm in time domain. Numerical implementation is employed into both steady and unsteady problems. The results with the resent method are shown to have good convergence on the circumferential distribution of circulation on the duct. The effect of the propeller tip clearance on the circumferential circulation on the duct is also presented Numerical results on forces and moments of the propeller and the duct are compared with other numerical results and experimental data.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.3
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• pp.372-379
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• 1998

Feeding habits of Favonigobius gymnauchen collected from the eelgrass bed in Kwangyang Bay from January 1994 to December 1994 were studied. Favonigobius gymnauchen was a carnivore which consumed mainly gammarid amphipods, polychaetes, crabs and copepods. Its diets included minor Quantities of gastropods, tanaids and isopods. It showed ontogenetic changes in feeding habits. Small individuals (1$\~$2 cm) fed mainly on gammarid amphipods, polychaetes, and copepods. While the portion of the stomach contents attributable to polychaetes and crabs increased steadily with incensing fish size, consumption of copepods decreased progressively. Gammarid amphipods were the most selected prey item for all size classes. Although gammarid amphipods, polychaetes, crabs and copepods were major prey organisms for all seasons, the relative proportion of these food items changed with season. Consumption of copepods was relatively high in spring and fall and consumption of gammarid amphipods, polychaetes and crabs was relatively high in summer.

• Parasites, Hosts and Diseases
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• v.30 no.4
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• pp.329-340
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• 1992

In order to determine population dynamics of Anopheles sinensis, a survey based on average number of female mosquitoes per trap-night was carried out during the period of 5 years from 1987 to 1991, A. sinensis Birst appeared between the 2nd and 20th April, and were trapped in large number between the 5th and 12th July. The number of trapped mosquitoes began to decrease from mid-August, and a few were collected until mid-November, each year. The average number of A. sinensis in July was 542.6 per trap-night in 1987, but in 1989 increased abruptly to 1,331.4, and then decreased to considerably lower levels, 271, 9 in 1990 and 372. 1 in 1991. The nocturnal activity of A. sinensis to attack humans was found to become active in the early night, and it was gradually decreasing at mid·night, however, then slightly increasing toward dawn. The immature stage of A. sinensis in the rice paddies was Birst found in the correlation pattern with peak adult densities in early July. The highest larval density of A. sinensis in the study area was 21,226×103 in early July 1990. The larval A. sinensis showed high resistance level and resistance ratios against 3 kinds of organo- phosphorous compounds, diazinon, malathion, and fenitrothion, but low resistance against fenthion. The present results indicated that the population density of A, sinensis in Kyongbuk area is decreasing over the five·year from 1987 to 1991. Key words: Anopheles sinensis, seasonal prevalence, population dynamics, Kyongbuk Province.

• Journal of Ocean Engineering and Technology
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• v.30 no.2
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• pp.125-133
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• 2016

In this paper, we propose a vertical axis water turbine with dual blades. A parametric study was conducted using numerical analyses. First, a two-dimensional finite-volume analysis with a commercial code was used to find the pitch angle of the main blade under different tip speed ratio conditions. Second, we developed a potential-based panel method to find the best configuration of the inner blades. Experimental tests were conducted at the circulating water channel of Chungnam National University. Various configurations of the dual blades were considered, and their performances were comparatively investigated. The results showed that the turbine with movable dual blades produces a constant torque and tip speed ratio at various flow rates.

• Korean journal of applied entomology
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• v.56 no.4
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• pp.345-350
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• 2017

Sunflower, selected as a trap plant that can be controlled by attracting Ricania spp. adults via attraction has the highest attractiveness during the preoviposition period. Considering the ecological characteristics of Ricania spp., adults are distinguished by the preoviposition and oviposition periods and the attractiveness of sunflower to Ricania spp. adults was 91.4~95.2% higher than that of blueberry during the preoviposition period. On August 20, when Ricania spp. adults entered the oviposition season, sunflower attractiveness was low at 9.8~11.6% owing to preference for tree species. Based on the result of the selection of systemic chemicals that could be used concomitantly with sunflower, all chemicals, except etofenprox, showed a high controlling effect of over 90%, and among them, dinotefuran showed the highest insecticidal rate of 95.8%. The systemic chemicals acetamiprid, dinotefuran, thiamethoxam, and imidacloprid persisted for 13 days (survey period). Therefore, the concomitant use of sunflower and systemic chemicals can reduce the density of Ricania spp. entering farmlands and their populations in surrounding habitats, which are expected to help in stabilizing the ecosystem.

• FLOWER RESEARCH JOURNAL
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• v.18 no.1
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• pp.38-43
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• 2010

To develop Korean native lilies as mini-potted plants, the effects of plant growth retardants on inhibiting stem elongation and improving flowering rate were evaluated. Bulblets of Lilium concolor var. parthneion (5-7 g) and L. dauricum (3-4 g fresh wt) derived from in vitro culture and then enlarged by field culture were applied with 0, 25, 50, or $100mg{\cdot}L^{-1}$ ancymidol, diniconazole, and uniconazole through bulb dipping, foliar spray, and drench. In L. concolor var. parthneion, uniconazole dipping most effectively reduced plant height by 60.7-78.3% depending on concentration compared with control without decreasing flowering percentage. In L. dauricum, dipping into diniconazole solution significantly retarded the plant height by 70.0-86.3% and improved flowering percentage by 8.3-18.2% compared to control of 0%. Drench of $25-50mg{\cdot}L^{-1}$ ancymidol was also effective on inhibition of stem elongation and improvement of flowering rate. Therefore, dipping into $50-100mg{\cdot}L^{-1}$ uniconazole solution in L. concolor var. parthneion and dipping into $25mg{\cdot}L^{-1}$ diniconazole solutions or drench of $25mg{\cdot}L^{-1}$ ancymidol in L. dauricum can be useful to produce the mini-potted plants.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.2
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• pp.234-241
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• 2015

This study investigated the effects of different cooking methods on contents of cholesterol, retinol, and tocopherol in poultry meats (chicken, Korean native chicken, and duck) using saponification extraction and HPLC analysis. The cooking methods were boiling, grilling, stir-frying, deep-frying, steaming, roasting, and microwaving. Generally, contents of cholesterol increased after cooking. Especially, after deep-frying, large amounts of cholesterol were detected from legs of chicken (94.25 mg/100 g) and wings of Korean native chicken (132.96 mg/100 g). High cholesterol content was detected in wings (233.77 mg/100 g) from duck after microwaving. However, contents of retinol decreased after cooking. The retinol contents of breast meat from Korean native chicken were low ($0.86{\sim}0.56{\mu}g/100g$) compared to other meats ($1.10{\sim}22.66{\mu}g/100g$ in chicken and $1.96{\sim}36.80{\mu}g/100g$ in duck), whereas raw materials from wings of all poultry showed the highest tocopherol contents. Of the various cooking methods, stir-frying and deep-frying resulted in increased ${\alpha}$-tocopherol contents in meats.