• 한국수산과학회지
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• 제37권1호
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• pp.24-32
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• 2004

A mathematical model is used to investigate nitrogen dynamics in the intensive aquaculture ponds in the western coast of Korea. Parameters associated with water quality, sediments and growing of shrimp (Fenneropenaeus chinensis) are measured to calibrate the model for feeding ponds A and B and storage ponds. The model describes the fate of nitrogen including loadings of ammonia from feeds, phytoplankton assimilation, nitrification, sedimentation, volatilization and discharge. The model obtains good agreements with the measured values of TAN $(NH_4,\;NH_3),\;NO(NO_2,\;NO_3)$ and Chl (chlorophyll a). Impacts of water exchange on TAN and Chl are investigated, showing that the range of 0.01-0.2 (/day) cannot effectively reduce TAN but reduces Chl. Nitrogen in the ponds A is removed by sedimentation $66\%,$ volatilization $8\%,$ discharge of particulate and dissolved $8\%.$ The pond B shows $56\%\;and\;26\%$ of sedimentation and volatilization, respectively, to yield $10\%.$ decrease and 8c/o increase compared to those in the pond A. While the pond A has larger area (1.02:0.66 ha) and same stocking density (0.025 md./L) at the beginning of culture, the pond B obtains higher stocking density (0.0065:0.0091 md./L), longer feeding period (103:121 day) and resultant higher shrimp production (1.15:2.13 t/ha/cycle) at harvest. This is possibly due to the hydraulic characteristics driven by paddlewheels. At low ratio of the low speed area and the pond area, the rate of sedimentation is high, while the rate of gas exchange is low. Thus, the measurement and model analysis suggest that water quality and shrimp production are positively correlated with the hydraulic characteristics in the shrimp ponds.

• 한국잠사곤충학회지
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• 제44권1호
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• pp.13-18
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• 2002

한반도에 자생하는 돌뽕나무를 수집하여 그 형태학적 특성을 조사한 결과는 다음과 같다 1.체세포의 염색체수는 2n=84인 6배체이다. 2.웅화수는 3.6~6.0cm의 긴 원통형이고 무화주인 자화수의 길이는 18 mm로 왜소하고 자 색 또는 자홍색의 오디는 1.39~l .65 g이다. 3. 동동아는 가지에 비하여 매우 크고 부아는 존재하지 않는다. 4. 잎은 대형의 열엽 또는 전연엽이며, 피목 밀도는 9.42$\pm$1.29개/$\textrm{cm}^2$이다. 5. 잎의 모용 길이는 236~438$\mu\textrm{m}$이고, 이면에 밀도가높은 바 16~37개/25 $\textrm{mm}^2$분포한다. 6. 잎의 표면의 모용형태는 원추형, 이면의 것은 매우 세장한 원추형이다

• Asian-Australasian Journal of Animal Sciences
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• 제14권11호
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• pp.1592-1597
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• 2001

Sixteen pigs from 2 distinct genetic lines (LGAH and VFIL) obtained after eight generations of divergent selection for high (H) and low (L) lean tissue growth rate with ad-libitum feeding (LGA) and voluntary feed intake (VF1), respectively, were used in this study. The objectives of this investigation were to establish appropriate working conditions for the postheparin plasma lipoprotein lipase (LPL) assay and to study relationships between fat deposition and plasma lipids, very low density lipoprotein (VLDL) lipids, VLDL-subfractions and postheparin plasma LPL activity in growing pigs. Four preliminary experiments were performed to determine the appropriate working conditions for the postheparin plasma LPL assays. Postheparin plasma preincubated with SDS (20-50 mM) at $26^{\circ}C$ for 45 minutes inhibited hepatic lipase activity. A total of $2{\mu}l$ VLDL/assay produced maximum stimulation of LPL activity. Postheparin plasma protein and increasing incubation time contributed an optimum response. LGAH pigs had a significantly higher proportion subtraction 2 than VFIL pigs. No differences were observed in postheparin plasma LPL activity and backfat thickness for two lines of pigs. There were positive correlations between backfat thickness and proportion of subtractions 2 and postheparin plasma LPL activity but the results were not statistically significant. Backfat thickness was not statistically correlated with proportion of subtraction 2 and postheparin plasma LPL activity in a multiple regression analysis. It is believed that the apolipoprotein E, which is present in higher quantities in VLDL-subfraction 2 plays an important role for clearing VLDL triacylglycerol into adipose tissue. LPL activity of pigs can be measured by using postheparin plasma technique. If the relationships of backfat thickness and VLDL-subfraction 2 and postheparin plasma LPL activity can be established, it suggests that these parameters could be used as indicators in selection programmes. Further experiments need to be conducted by using larger sample size and different breed of pigs with greater differences in backfat thicknesses to confirm these trends.

• Journal of the Korean Wood Science and Technology
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• 제48권1호
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• pp.41-49
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• 2020

Jabon (Anthocephalus cadamba) is a fast-growing wood species that is widely utilized for light construction and other purposes in Indonesia. The objectives of the current study were to determine the effects of monoethylene glycol (MEG) and SiO₂ nanoparticles (nano SiO₂) impregnation treatment on the dimensional stability and density of jabon wood and to identify the characteristics of impregnated jabon wood. Wood samples were immersed in water (as untreated), MEG, 0.5% MEGSiO₂, then impregnated by applying 0.5 bar of vacuum for 60 min, and then applying 2.5 bar of pressure for 120 min. The results showed that impregnation with MEG and Nano SiO₂ had a significant effect on the dimensional stability of jabon wood. Polymers can fill cell walls in wood indicated by increasing weight percentgain, antiswelling efficiency, bulking effect, and density, then decreasing in water uptake value. Jabon wood morphology by using SEM showed that MEGSiO₂ polymers can cover part of the pitsin the wood vessel wall of jabon. This finding was reinforced by EDX results showing that the silicon content was increased due to the addition of SiO₂ nano. The XRD diffraction pattern indicated that MEGSiO₂ treatment increased the degree of crystallinity in wood samples. Overall, treatment with 0.5% MEGSiO₂ led to the most improvement in the dimensional stability of 5-year-old jabon wood in this study.

• 한국작물학회지
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• 제27권4호
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• pp.361-370
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• 1982

The effects of climatic factors on organisms lire variable and complex, and it, however, can be interpreted in terms of those on the distribution and those on the population densities. The distribution of an organism may largely be determined by the temperatures, except some temporal organisms which are depended on the air mass movements. Population density of an organism is determined by various climatic factors, such as previous winter temperature, temperature of growing season and rainfall. The start of growing season of the rice plants has been shifted to earlier since last decade in Korea. This may mean that the overall climatic condition during the growing season might be considerably different from those in past years, and such a difference in climatic conditions might have close relation with the recent status of the diseases and insect pests through direct effects on the physiology and population dynamics of the organisms, as well as through on the biotic associations of the pest organisms. The white back planthopper and brown planthopper have become the key insect pests in Korea in recent years. They are migratory and have high reproductive pontentials and more generations than average residential insects. The synchronization of the migrants and physiological condition of the rice plants seems to be the important factors in relation to the recent outbreaks of these insects; the high reproductive rate can be obtained with the growth stage of rice being 30-50 days after transplanting. The modication of the microclimate associated with high plant density and some other introduced new cultural techniques also have some relation with the outbreak. The key diseases of the rice are the blast disease, sheath blight and the bacterial leaf blight. For the rice blast, the seedling blast and leaf blast during the early growing season and the neck blast, have become more serious, the former may be related to hotbed nursery and the later may be related to the high humidity in early August, and synchronization of the heading time which has been shifted to early part from middle or late part of August. In general, for the rice diseases, the development of the new races have been the most serious which are largely resulted from the introduction of the new varieties, but it also seems to be related with the prolonged periods of the favorable condition associated with the shifted growing seasons. In general, the diseases and insect pest problems have become much more variable and complex, and control measures should be based on the thorough knowledge of the ecology of the pest organisms, that is, effects of various environmental factors on the disease cycle; spore release, spore deposition, infection, colonization and sporulation of the disease organisms, and those on the development, reproductive potentials, dispersal, age specific responses of the insects. The well organized real-time pest management systems, such as alfalfa weevil management system developed at the Purdue University in U.S., is the prime importance for the implementation of the pest management principles.

• Journal of Animal Science and Technology
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• 제61권4호
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• pp.204-215
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• 2019

This experiment was conducted to evaluate the effect of dietary energy and crude protein (CP) levels on growth performance, blood profiles, and carcass traits in growing-finishing pigs. A total of 180 crossbred pigs ([Yorkshire ${\times}$ Landrace] ${\times}$ Duroc) with an average body weight of $30.96{\pm}3.068kg$ were used for a 12-week feeding trial. Experimental pigs were allotted to a $2{\times}3$ factorial arrangement using a randomized complete block (RCB) design. The first factor was two levels of dietary metabolizable energy (ME) density (13.40 MJ/kg or 13.82 MJ/kg), and the second factor was three dietary CP levels based on subdivision of growing-finishing phases (high: 18%/16.3%/16.3%/13.2% middle: 17%/15.3%/15.3%/12.2% and low: 16%/14.3%/14.3%/11.2%). Average daily gain (ADG) and gain-feed ratio (G:F ratio) decreased as dietary CP level was decreased linearly (linear, p < 0.05; p < 0.05, respectively) in the early growing period, and G:F ration also decreased as dietary CP level was decreased linearly (linearly, p < 0.05) over the whole growing phase. Over the entire experimental period, G:F ratio decreased as dietary ME level decreased (p = 0.01). Blood urea nitrogen (BUN) concentration was increased as dietary energy level decreased in growing period (p < 0.01). During finishing period, total protein concentration was decreased by lower dietary energy level (p < 0.05). In this study, there were no significant differences in proximate factors, physiochemical properties, muscle TBARS assay results, pH changes, or color of pork by dietary treatments. However, saturated fatty acid (SFA) increased (p < 0.01) and polyunsaturated fatty acid (PUFA) decreased (p < 0.05) when ME was decreased by 0.42 MJ/kg in growing-finishing pig diets. In addition, monounsaturated fatty acid (MUFA) tended to increase when CP level was decreased in growing-finishing pig diets (p = 0.06). A growing-finishing diet of 13.82 MJ/kg diet of ME with the high CP level can improve growth performance and show better fatty acids composition of pork.

• 한국초지조사료학회지
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• 제26권4호
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• pp.285-292
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• 2006

본 연구는 양마 3품종을 재식거리, 품종 및 수확시기에 따른 건물수량과 사료성분의 변화를 검토하고자 강원도 철원지역에서 2005년 5월 20일부터 2005년 9월 12일까지 수행되었다. 시험배치는 3반복 분할구 배치로 주구는 재식거리와 수확시기를, 세구는 양마 3품종(Dowling, Everglade 및 Tainung)을 배치했으며, 결과를 요약하면 다음과 같다. 생육일수에 따른 건물 생산량은 93일까지는 재식거리가 $10{\times}10cm^2$ 구에서 높게 나타났다. 품종별 건물생산량에서는 모든 품종이 생육시기가 진행됨에 따라 건물수량이 높아지는 경향을 보였고, 특히 Bowling이 모든 수확시기에서 가장 높은 건물생산량을 보였다. 조단백질 함량은 생육일수가 길어짐에 따라 감소하는 경향을 보였다. 특히, 생육 중기(생육일수 84일)을 기준으로 생육초기에는 조단백질 함량은 큰 차이를 나타내지 않았지만, $10{\times}20cm^2$ 구에서 다소 높게 나타났다. 품종별로는 Bowling의 조단백질 함량이 다소 높은 것으로 조사되었으나, 큰 차이는 나타내지 않았다. 재식거리 및 품종에 따른 NDF와 ADF 함량의 차이는 조사된 3 품종 공히 생육시기가 지나감에 따라 다소 증가하는 경향을 보였지만, 큰 유의적 차이는 나타나지 않았다. 이상의 결과를 종합해 보면, 양마는 우리나라 중북부 지방에서 훌흉한 사료작물로서의 가능성이 검증되었고, 특히 Bowling 품종이 재식거리 $10{\times}10cm^2$로 파종하여 104일째 수확했을 때 가장 좋은 건물생산량과 품질을 보여주었다.

• The Korean Journal of Ecology
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• 제28권5호
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• pp.287-293
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• 2005

본 연구는 1996년부터 1998년까지 경기도 화성시 발안 지역의 이앙재배한 논에서 발생하는 거미의 개체군 동태 및 군집자료를 바탕으로 관행의 살충제 살포가 거미군집에 미치는 영향을 분석하기 위해 수행되었다. 3년간 조사에서 조사 포장들에서 거미군집은 연간 변이가 적은 안정된 발생을 보였으며, 발생밀도에서 천적군의 90% 이상을 차지하는 최대 우점군이었다. 이 지역의 벼 생육기간동안 단위면적당$(0.25m^2)$ 평균 거미밀도는 약 10마리 정도였으며, 늑대 거미과(Lycosidae), 갈거미과(Tetragnathidae), 접시거미과(Linyphiidae)가 우점하였다. 거미군집의 밀도는 본답 초기에 벼의 이앙과 함께 이입으로 인해 형성되기 시작하여 중기부터 급격한 밀도 증가를 보이며, 후기에 최고밀도를 유지하다가 수확시기에 밀도가 감소하는 패턴을 가졌다. 특히, 비래 해충의 발생이 적었던 해에는 관행적인 살충제 살포에 의한 거미군집의 교란 효과가 적게 나타났다. 우점종인 황산적거미와 턱거미는 다소 다른 개체군 동태를 가졌는데, 황산적거미는 7월 중순부터 밀도가 급격히 증가하고, 후기에는 성체보다는 유체들의 발생비율이 높았던 반면, 턱거미는 8월 말부터 밀도가 급격히 증가하였고, 후기에 성체형태로 대부분 발견되었다.

• 기술사
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• 제2권6_7호
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• pp.12-23
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• 1969

The purpose of this study is to find out the reasonable amount of evapo-transpiration required for the paddy rice plant during the whole growing season. So, on the basis of the 3year experimental data concerning the evapo-transpiration from 1966 to 1968, the author obtained the following results. 1) The leaf area index in the densely planted plot is generally higher than that in the conventionally planted one during the first half of growing season. So, the coefficient of transpiration in the former plot is some what higher than in the latter, and the coefficient of water surface evaporation under the plant cover has the inverse relation between both plots. 2) It is unreasonable that coefficient of evapo-transpiration is applied to the calculation of the evapo-transpiration requirments of each growing stage, because a certain degree of variation in meteorological factors and in the thickness of the plant growth is involved in it. 3) It is most reasonable that the rate of transpiration and of the water surface evaporation is applied to the calculation of the transpirated amount and evaporated one in each growing stage because it shows almost constant value in spite of any meteorological conditions in so far as the variety of rice, planted density and control of applying fertilizer are same and the disease and blight are negligible. 4) The ratio of the amount of transpiration to the weight of the whole air dried yields has the tendency of decreasing as that of the yields increase, having almost constant value despite the amount of pan evaporation; and the value is about 210 when the weight of root parts is included to that of the yields. 5) Although the required amount of transpiration during the whole growing season can be calculated with the above ratio, fig. 7 showing the relation between the amount of transpiration and the weight of the yields is more reasonable and will be convinient to find it. And the requirements of water surface evaporation during the same season can also be directly found with the weight of air dried straw refering to fig.8.

• 한국토양비료학회지
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• 제44권1호
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• pp.91-97
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• 2011

The objectives of this research were to investigate the system of rice intensification (SRI) on early growth, grain yield, and yield components under Chinese milk vetch residue-mulched no-tillage cropping systems at silt loam soil. The field was prepared as a split-plot design with three replications, main plots consisted of Dongjinbyeo, and Sobibyeo as a cultivar, and subplots consisted of $10{\times}10$ cm, $20{\times}20$ cm, and $30{\times}30$ cm as a planting density. Weed infestation during rice growing season was more severe in wider planting density $30{\times}30$ at 35 days after transplanting (DAT), and $20{\times}20$ cm at 95 DAT in both Sobibyeo and Dongjinbyeo. The maximum plant height was recorded in Sobibyeo compared with Dongjinbyeo, $10{\times}10$ cm and $20{\times}20$ cm planting density compared with $30{\times}30$ cm from 20 DAT until 60 DAT. Among the three planting densities, SPAD values were significantly greater in planting density of $20{\times}20$ cm both in Sobibyeo and Dongjinbyeo followed by $30{\times}30$ cm compared with closer planting density of $10{\times}10$ cm. The lowest grain yield was observed in wider planting density of $30{\times}30$ in both Sobibyeo and Dongjinbyeo due to lower number of panicle per unit area. Our findings suggest that optimum planting density for SRI in no-tillage paddy was $20{\times}20$ cm and it should be useful the systems to small-scale rice farmers in Korea as a sustainable farming system.