• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.11A
• /
• pp.1642-1651
• /
• 2000

위성통신시스템에서의 10GHz이상의 Ku 또는 Ka 대역은 수십 dB의 크기를 갖는 강우에 의한 감쇠 현상이 심각하여 이러한 감쇠는 위성 링크의 심각한 성능 정하를 가져온다. 본 논문은 위성통신 링크 상에서의 강우 감쇠 보상을 위한 알고리즘을 제시하고, Ku 대역의 강우 감쇠 데이터를 사용한 시뮬레이션을 통하여 그 성능을 비교 분석하였다. 예측 기법 측면에서, 적응형 알고리즘을 적용한 기법과 신호 레벨 변화량에 근거한 예측 기법은 거의 동일한 예측 오차를 보였고, 따라서, 급속한 신호레벨 변화에 적응성을 요하지 않은 강우 감쇠 예측의 경우, 알고리즘 측면에서 비교적 간단한 예측 기법으로도 충분한 성능을 얻을 수 있음을 확인하였다. 또한, 제시된 전송 방식 결정 알고리즘은 기존의 임계값 기반 알고리즘에 비해 품질 저하율이 0.6%에서 0.01% 이하로 감소하였고, 거의 동일한 전송 효율을 가지면서 약 5배의 적은 전송 방식 전환을 요구한다.

• Journal of Practical Agriculture & Fisheries Research
• /
• v.20 no.1
• /
• pp.107-123
• /
• 2018

The global impact of climate change on agriculture is now increasing. The purpose of this study was to investigate the effect of climate change on livestock productivity. The variables that have the greatest influence on climate change factors were examined through previous studies and expert surveys. We also used the actual productivity data of livestock farmers to investigate the relationship with climate change. In order to evaluate the climate for changes in livestock productivity, national representative data (such as bullocks, dairy, pigs, laying hens, and broilers) were surveyed in Korea. Also, to select and classify evaluation indexes, we selected climate change factor variables as prior studies and studied the weighting factor of climate variable factors. In this study, the researchers of industry, academia, and farmers in the livestock sector conducted questionnaires on the indicators of vulnerability to climate change using experts, and then weighed the selected indicators using the hierarchical analysis process (AHP). In order to verify the validity of the evaluation index, was examined using domestic climate data (temperature, precipitation, humidity, etc.). Correlation and regression analysis were performed. The empirical relationship between climate change and livestock productivity was examined through this study. As a result, we used data with high reliability of statistical analysis and found that there are significant variables.

• Proceedings of the Korea Society of Poultry Science Conference
• /
• 2002.11a
• /
• pp.130-132
• /
• 2002

This experiment was conducted to investigate the influence of different dietary ME and CP on post-molt performance of spent laying hens. Four hundred and thirty two, ISA brown after molt induction were fed 6 experimental diets containing 3 ME(2,750, 2,800, 2,850 kcal/kg) and 2 CP(15, 17%) levels in factorial design. The influence of ME and CP were measured on body weight, egg production, egg weight and feed intake throughout 24 weeks of production. Egg mass and FCR were calculated for the entire experimental period body weight remained less in hens receiving 2,800 kcal/kg. ME and showed the highest egg Production coupled with 15% CP. Feed intake decreased with the increasing level of ME and CP. As the results of this experiment, 2,800 kcal/kg ME can be used to maintain the low body weight and to obtain higher egg production with 15% CP in induced molting hens.

• Korean Journal of Poultry Science
• /
• v.31 no.4
• /
• pp.265-271
• /
• 2004

A feeding trial was conducted to investigate the influence of feeding Lactobacillus reuteri culture (LR) on productive performance, intestinal microflora and availability in laying hens. Four hundred and eighty, Isa-Brown layers, 49 weeks of age, were fed diets supplemented with LR at the level of 0 (control), 0.1, 0.2, and $0.4\%$ of the diets for eight weeks. Egg production and egg weight were measured daily. Feed intake was weighed every two weeks. Egg quality was measured three times at the start, mid-term, and end of the experiment. Intestinal microflora were examined for Lactobacillus spp., E. coli and Salmonella at the end of the experiment. Overall egg production was the highest in $0.2\%$ LR (P<0.05), but that of $0.1\%$ or $0.4\%$ LR treatments did not significantly differ from that of control. Egg weight was significantly higher in LR feeding group than the control (P<0.05). Daily egg mass was significantly higher in $0.2\%$ and $0.4\%$ LR treatments compared to the control and $0.1\%$ LR (P<0.05). The number of jumbo and extra large eggs were increased in LR supplemented groups, especially in $0.1\%$ LR. Feed intake of layers fed LR supplemented diets tended to be lower than the control. However, feed conversion ratio significantly improved in LR supplemented groups (P<0.05). Availability of dry matter and crude protein improved significantly in $0.4\%$ LR treatment (P<0.05). But, those of ether extract and crude ash were not significantly different among treatments. Eggshell breaking strength and eggshell thickness were not significantly influenced by LR supplementation, and Haugh unit and yolk index were also similar to the control. Total number of Lactobacillus spp. in ileum and cecum fed LR supplemented diets were significantly higher than those of the control (P<0.05). There were no significant differences in intestinal E. coli and Salmonella in all treatments. Therefore, it is concluded that dietary supplementation of Lactobacillus reuteri culture can improve the laying performance, feed efficiency and intestinal Lactobacillus.

• Journal of Drive and Control
• /
• v.14 no.2
• /
• pp.16-22
• /
• 2017

This paper presents the algorithm of an adaptive model-free-control-based steering control for multi-axle all-terrain cranes for which the recursive least squares with forgetting are applied. To optimally control the actual system in the real world, the linear or nonlinear mathematical model of the system should be given for the determination of the optimal control inputs; however, it is difficult to derive the mathematical model due to the actual system's complexity and nonlinearity. To address this problem, the proposed adaptive model-free controller is used to control the steering angle of a multi-axle crane. The proposed model-free control algorithm uses only the input and output signals of the system to determine the optimal inputs. The recursive least-squares algorithm identifies first-order systems. The uncertainty between the identified system and the actual system was estimated based on the disturbance observer. The proposed control algorithm was used for the steering control of a multi-axle crane, where only the steering input and the desired yaw rate were employed, to track the reference path. The controller and performance evaluations were constructed and conducted in the Matlab/Simulink environment. The evaluation results show that the proposed adaptive model-free-control-based steering-control algorithm produces a sound path-tracking performance.

• Proceedings of the Korean System Dynamics Society
• /
• 2004.08a
• /
• pp.87-107
• /
• 2004

우리나라에 이동통신이 처음 소개된 이래로 눈부신 발전을 거듭하여 왔으며, 급기야. 무선통신 서비스를 중심으로 새로운 성장력과 패러다임 전환의 가능성에 대한 전망을 논할 수 있는 수준이 되었다. 이러한 추세에 맞추어 휴대인터넷 시장에 대한 연구가 활발히 진행되고 있으며 국민경제적 효과변화나 시장 경쟁환경의 변화에 가장 영향을 미칠 수 있는 요인들 중, 사업자 수를 어떻게 선정할 것인가에 대해 다양한 접근이 시도되고 있다. 기존의 연구들은 휴대인터넷 시장을 분석하는데 있어 시장규모가 일방향으로 사업자 수에 영향을 미친다는 측면에서 이루어지고 있으며, 대부분 휴대인터넷 시장을 단일시장으로 범위를 한정하고 성장중인 시장을 정적으로 가정하여 시장성장 추이 분석 등에 주안점을 두는 단편적 연구가 수행되어져 왔다. 휴대인터넷 시장의 단편적 분석이 아닌 '모바일인터넷' , '초고속유선인터넷', '무선인터넷', '휴대인터넷' 등 네 가지 영역을 동시에 고려함으로써 영역간 복잡성과 동적인 관계 속에서 시장이 성장해 나아간다는 가정을 바탕으로, 시장에 내재되어 있는 관련요소간 상호영향과 신규정책 및 제도적 변화 수용에 있어 발생하는 시간적 공간적 지연 등을 고려한 동태적 분석을 수행하였다. 연구를 수행하기 위해 다양한 변수간의 인과관계, 피드백 구조와 시간흐름에 따른 시스템의 변화를 파악하는데 매우 유용한 도구인 시스템다이내믹스 기법을 활용하여 휴대 인터넷 시장의 동적인 구조를 알아보고 사업자 선정정책의 시행을 앞두고 있는 현재시점에서 의미있는 시사점을 제공하였다.시하고자 한다.채취하여 임신진단키트(제네디아프로테 트, 녹십자)를 이용하여 임신여부를 1차적으로 확인하였다. 과배란을 유기한 13두의 공란우중 9두(69.2%)가 과배란 반응을 나타내었으며, 회수된 수정란 51개중 이식가능수정란은 38개(74.5%) 였다. 발정동기화를 유도한 수란우 40두중에서 35두(87.5%)가 발정이 동기화되었으며, 그 중 황체검사를 통하여 30두의 수란우에 수정란을 이식하였다. 수정란이식후 13일(발정주기 21일)에 혈액을 이용한 임신진단에서 농가별 수태율은 각각 37.5%, 70.0%, 60.0% 및 71.4% 로서 평균 60.0%를 나타내었다.서 39$^{\circ}C$, 5% $CO_2$ 배양기에 48시간 배양하면서 생존여부를 판단하였다. 실험 2에서 확장배반포배 수정란이 25.3%의 생존율을 나타내었으며, 실험 1과 실험 3에서는 수정란의 형태와 관계없이 생존성을 확인할 수 없었다. 이상의 결과로 보아 glycerol 완만동결에서는 확장배반포기 수정란 이상이 보존가능한 것으로 추정되나 더 추가적인 연구가 요구된다.c kinase 활성의 변동은 정소 내 간충조직, 세정관 상피의 증식 및 기능적 분화 과정을 매개하는 생리적 활성분자 수용체 하위의 신호전달 과정에 Src-Csk loop에 의한 조절가능성을 확인할 수 있었다.rugrene의 향기성분이 주요 성분군으로 확인되었다. 2. 생강나무에서 생강의 향기를 발산하는 성분으로는 $\beta$-myrcene, o-terpinolene, phellandrone, ι-limonene, $\b

• KDI Journal of Economic Policy
• /
• v.13 no.2
• /
• pp.3-19
• /
• 1991

This paper attempts to identify key determinants of long run movements of real M2 by using the Johansen procedure for estimating and testing cointegration relations. It turns out that the real M2 equation has been stable over the long run despite rapid changes in financial structure since 1975. Moreover, the real M2 equation can be reduced to a velocity equation with the opportunity cost variable, expected inflation less the weighted average rate paid on M2 deposits, being the key determinant. However, it does not work to use a market interest rate such as the yield on corporate bonds in place of expected inflation for calculation of the opportunity cost. In the U.S., a market interest rate can be used, but not in Korea. Presumably, two somewhat different reasonings can be used to explain this result. One is that the yield on corporate bonds may not adequately reflect the inflationary expectations due to regulations on movements in interest rates. The other is that M2 deposits are not readily substitutable with such assets as corporate bonds because of market segmentations, regulations, and so on. From the policymaker's point of view, this implies that the inflation rate is an important indicator of a policy response. On the other hand, policymakers do not regard movements of the yield on corporate bonds as an important policy indicator. Altogether, the role of interest rates has been quite limited in Korea because of incomplete interest rate liberalization, an underdeveloped financial system, implementation procedures of policy measures, and so on. The result that M2 velocity has a positive cointegration relation with expected inflation minus the average rate on M2 implies that frequent adjustments of the regulated rates on M2 will be necessary as market conditions change. As the expected inflation gets higher, M2 velocity will eventually increase, given that the rates on M2 do not change. This will cause higher inflation. If interest rates are liberalized, then increases in market interest rates will result in lagged increases in deposits rates on M2. However, in Korea a substantial portion of deposit rates are regulated and will not change without the authority's initiatives. A tight monetary policy will cause increases in a few market interest rates. But the market mechanism, upward pressure for interest rate adjustments, never reaches regulated deposit rates. Hence the overall effects of tight monetary policy diminish considerably, only causing distortions in the flow of funds. Therefore, frequent adjustments of deposit rates are necessary as market conditions such as inflationary expectations change. Then it becomes important for the policymaker to actively engage in adjusting regulated deposit rates, because the financial sector in Korea is not fully developed.

• Journal of Family Resource Management and Policy Review
• /
• v.26 no.2
• /
• pp.71-84
• /
• 2022

This study analyzed 2019 time survey data from the National Statistical Office to examine the childcare behaviors of fathers with preschool children and their determinants, considering types of care and working/nonworking days. The main results of this study are as follows. First, paternal childcare time of nonworking days was three times more than that of working days, and the participation rate was also higher on nonworking days. Second, there was no significant difference in the amount of time spent on primary care and developmental care by fathers, whether from dual- or single-income families. Third, it seems that fathers adjust their participation in childcare between working days and nonworking days in consideration of the mother's time availability. Fourth, the variables related to childcare needs had a significant influence on paternal childcare time on both working and nonworking days. Fathers' developmental care time was not explained by the independent variables entered into the regression analysis. As a result of the study, it is necessary to reduce fathers' working hours and increase family-friendly systems to increase fathers' participation in childrearing. Fathers' perception of parental responsibility must also be changed.

• Journal of Korean Society of Forest Science
• /
• v.78 no.3
• /
• pp.314-322
• /
• 1989

For the improvement of nursery condition and the study of eco-physiological characteristics of Pinus koraiensis(2-2) seedlings, the primary productivity was investigated and the growth characteristics and their correlationship were analyzed from May to September in 1987. Seedlings used in this study were grown at the nursery of Experimental Forestry of Kyung Hee Univ. The installation of experimental plots were divided into control plot (100%), 63%, 37% and 19% relative light intensity, and each relative light intensity plots were split into $15{\times}15/m^2$, $12{\times}12/m^2$, $9{\times}9/m^2$ and $6{\times}6/m^2$ plnting density by randomized black design method. To take into account the edge effect of plant population, material were selected from each plot by random sampling at 30 days interval. Each sampled material was divided into leaf and stem drived in a drying oven at the temperature of $85^{\circ}C$ until it had constant weight and weighed. and leaf area was surveyed. Growth analysis for RGR and NAR was done by Blackman method and correlation coefficient were investigated between RGR and NAR by analyzing the dry matter production and growth characteristics of the material, cultivated on the experimental nursery under the condition of different treatment the obtained result were as follows : 1. The increasing rate of dry matter was similar at early stage of growth, but not at late stage. 2. Leaf area growth was the maximum value at 63% relative light intensity and the minimum at 19% RLI 3. The value of RGR was the highest on June under $6{\times}6/m^2$ planting density in 63% relative light intensity, the lowest on September under $12{\times}12/m^2$ of 19% relative light intensity. 4. The change NAR decreased in early stage of growth, while it increased on August and September, The value of RGR on June under $6{\times}6/m^2$ planting density in 100 light intensity was the highest, and on September under $12{\times}12/m^2$ planting density in 19% relative light intensity was the lowest. 5. Regression and correlation between RGR and NAR showed significantly positive.

• Horticultural Science & Technology
• /
• v.33 no.4
• /
• pp.501-510
• /
• 2015

In this study, we investigated the onset and release of endo-dormancy under natural conditions by observing bud break characteristics in 'Fuji' apple trees using water cuttings. Through examinations of bud break rate and days to bud break, we found that the endo-dormancy of 'Fuji' apple tree continues for 70 d from 165 to 255 d after full bloom (DAFB), from late October to early January of the following year. In addition, within 20 d of first bud break, based on a final bud break rate of 60% or more, we able to identify the timing of the changeover from para-dormancy to endo-dormancy, and endo-dormancy to eco-dormancy. Analysis of the chilling requirement during the endo-dormancy period revealed that chilling accumulation up to 255 DAFB to release endo-dormancy amounted to 666 and 517 h based on the CH and Utah models, respectively. Observation of internal changes in the bud during endo-dormancy showed that flower bud differentiation begins from mid-July, and t ime of inflorescence o f the disk f lower is a vailable to f ind. The f lower buds subsequently developed slowly but steadily during endo-dormancy and in the following year in February, the developmental stage of each organ had progressed. Moreover, the flower buds of 'Fuji' apples were mostly healthy during the dormancy period, but some exhibited necrosis of flower primordium, due partial cell damage from the formation of ice crystals rather than a direct effect of the low temperature. Flower buds were formed in both the axillary buds of bourse shoots and terminal buds of spurs, but lower bud differentiation was observed for the terminal buds of spurs at rate of about 65% of total buds, which was directly related to the bud size and shoot diameter.