• Asian-Australasian Journal of Animal Sciences
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• 제17권6호
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• pp.794-798
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• 2004

An attempt was made to improve the efficiency of growth and lactation performance of dairy heifers subjected to a stair-step growth scheme using rice straw as the sole roughage source. Twenty-four young Holstein heifers were randomly assigned to either control or test group. The control diet met the National Research Council (NRC) requirement, with heifers calving at 24 to 26 mo of age. The test group was individually fed according to a schedule of 3, 2, 4, 2, 5 and 2 mo in which feed intake was alternately 20% below or 25% above the NRC requirements. Heifers on the stair-step growth pattern gained more body weight and consumed less dry matter (10.80 and 11.22%, respectively), resulting an increasing growth efficiency compared with the control. Body condition, first estrus, first conception, services per conception and calving difficulty (data not shown) were not affected. Milk yield of the test group was 8.5% higher than that of the control group. During the early lactation period, the milk yield was significantly higher in the stair-step group than in that of the control group (p<0.05). Milk composition was not affected by compensatory growth induced by the stair-step scheme. Also, weight at calving and calf growth performance was not affected by stair-step growth. The results indicate that using rice straw as a sole roughage source in a stair-step compensatory growth scheme can contribute to the improvement of growth efficiency and early lactation performance.

• 한국산학기술학회논문지
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• 제13권2호
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• pp.878-884
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• 2012

본 연구에서는 건설 기업을 중심으로 기업의 경영 효율성과 배당성향을 중심으로 한 효율적 포트폴리오를 선택하는 전략을 제시한다. 기업의 경영 효율성을 포트폴리오 선택에 반영하는 방안으로 DEA(Data Envelopment Analysis) 기법을 사용하였고 성장가능성은 기업의 배당 성향을 판단하는 배당 스코어링 테이블을 이용하여 평가하였다. 본 연구에서 제안한 포트폴리오 선택전략의 성능 실험을 위해 KOSPI와 KOSDAQ에 상장된 56개의 건설 산업 관련 기업의 주식을 대상으로 2007~2010년의 4년 동안 매해 3그룹의 포트폴리오를 구성하였고 각각의 포트폴리오 수익률을 벤치마크 수익률과 비교 분석하여 그 성능을 입증하였다.

• 한국수산과학회지
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• 제43권4호
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• pp.320-324
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• 2010

We investigated the proper feeding frequency and satiation rate for the growth of red- and white-colored carp fingerlings in a feeding experiment. Triplicate groups of fish averaging 6.3 g were fed diets at four feeding frequencies (1, 2, 3, or 4 meals a day) and two satiation rates (satiation and 80% satiation) for 6 weeks. The survival of the fish was not affected by either the feeding frequency or the satiation rate. The weight gain, feed efficiency, and protein efficiency ratio of fish were affected by the feeding frequency and satiation rate, and increased significantly with both. The feed efficiency and protein efficiency ratio with satiation feeding of fish fed four meals a day did not differ from those of fish fed three meals a day. The daily feed intake was affected by the feeding frequency and satiation rate. The moisture, crude lipid, and ash contents of whole body were affected by the feeding frequency. Moisture and crude lipid contents were affected by feeding satiation. Based on these results, we conclude that the proper feeding frequency and satiation rate for the optimum growth of red- and white-colored carp fingerlings is four meals a day with satiation feeding.

• 전기전자학회논문지
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• 제22권4호
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• pp.959-964
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• 2018

본 연구에서는 LED 광시스템과 식물생장제어시스템을 연계하여 센서를 이용하여 식물환경을 제어 가능한 모니터링시스템에 대한 연구이다. 시스템의 성능을 검증하기 위해 에너지효율, data 전송률, 광량제어 특성에 대한 실험을 실시하였다. 실험한 결과 에너지 효율은 80%이상, 무선통신속도가 1Mb/sec이고 광량제어를 5단계이상 조절 가능함으로써 만족한 결과를 얻었다. 제안된 시스템은 LED 식물공장설비에 적용가능하며, 향후 상용화를 위해서는 생산효율 및 노동비 절감을 위한 자동시스템을 구성하여 농업 자동화설비에 기여할 것이다.

• 산업경영시스템학회지
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• 제42권2호
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• pp.62-68
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• 2019

The growth and employment effects of R&D investment were analyzed according to business size, export value and manufacturing sectors so as to suggest improvement directions for effective industry policies. The effect of R&D investment was considered simultaneously from the two perspectives of growth and employment effect, and the causality analysis was carried out by using a path analysis. The result of the path analysis confirmed significant differences in the growth effect of R&D investment depending on business size. However, the effect of increasing employment was difficult to obtain statistically significant results for any various combinations of business size and export value. This is a mixture of directions for the effects of R&D investment on employment, which could be due to the failure to consider appropriate time lags between investment and effect. Efficiency analysis by industry sectors confirmed significant differences in efficiency depending on business size, but differences depending on export value were difficult to identify. In order to derive improvement policy by industry sector according to business size and export value, the direction of selective support policy and universal support policy was derived for six industry groups by combining the return to scale in the efficiency analysis and R&D concentration. Hirschman-Herfindahl index is used for calculating R&D concentration.

• 한국작물학회지
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• 제47권4호
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• pp.323-327
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• 2002

Plant growth and the two components of respiration, growth and maintenance, were compared between low and high nitrogen applications in hydroponic culture on a high-yielding rice cultivar 'Takanari' (Oryza sativa L.). Grain yield decreased by high nitrogen application, and thus this cultivar has low adaptability to nitrogen. Growth efficiency (GE) and net assimilation rate (NAR) were lower in the high-nitrogen plot. The maintenance coefficient (m) and growth coefficient (g) of dark respiration were 0.0111 $d^{-1}$ and 0.196 in the low-nitrogen plot and 0.0166 $d^{-1}$ and 0.237 in the high-nitrogen plot, respectively. Thus, high nitrogen application increased both g and m. Calculated $R_m$ (maintenance respiration rate) was 70 and 90% of total respiration rate at heading, respectively. The significance of nitrogen adaptability and g was discussed.

• Journal of Crop Science and Biotechnology
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• 제10권2호
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• pp.57-63
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• 2007

Due to the strong influence of nitrogen(N) on plant productivity, a vast amount of N fertilizers is used to maximize crop yield. Over-use of N fertilizers leads to severe pollution of the environment, especially the aquatic ecosystem, as well as reducing farmer's income. Growing of N-efficient cultivars is an important prerequisite for integrated nutrient management strategies in both low- and high-input agriculture. Taking maize as a sample crop, this paper reviews the response of plants to low N stress, the physiological processes which may control N-use efficiency in low-N input conditions, and the genetic and molecular biological aspects of N-use efficiency. Since the harvest index(HI) of modern cultivars is quite high, further improvement of these cultivars to adapt to low N soils should aim to increase their capacity to accumulate N at low N levels. To achieve this goal, establishment and maintenance of a large root system during the growth period may be essential. To reduce the cost of N and carbon for root growth, a strong response of lateral root growth to nitrate-rich patches may be desired. Furthermore, a large proportion of N accumulated in roots at early growth stages should be remobilized for grain growth in the late filling stage to increase N-utilization efficiency. Some QTLs and genes related to maize yield as well as root traits have been identified. However, their significance in improving maize NUE at low N inputs in the field need to be elucidated.

• 지역연구
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• 제13권2호
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• pp.143-155
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• 1997

This study aims at drawing implications for Korea's urban growth management policies from U.S.A's experience on this issue. This study analyzes two types of contradictions in planning and implementing urban growth management policies: 1) value conflicts in goal setting and 2) contradictions among different level of governments (local, province, nation). As mentioned by Campbell (1996), there are three types of conflicts in objective values (efficiency, equity, and environment protection): property contradiction between economic growth and equity, resource conflict between efficiency and environment protection, and development conflict between equity and environment protection in urban growth management policies. In implementing urban growth management three types of conflicts in goal values should been taken into consideration. Contradictions among local governments, province, and central government are also found in implementing growth management policies. The lessons from the United State are as follow: 1) growth management plans are initiated by the local government and during the planning process adjacent local governments review a local government's growth management plans and give inputs for the plan, 2) local government and State work together for growth management planning and specially, the State provides technical and financial assistance to local government, and 3) the State plays leading roles in local government's planning and implementing of growth management policies with carrot and stick policy.

• 산업경영시스템학회지
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• 제44권3호
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• pp.248-261
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• 2021

Scientific and technological performances (e.g., patents and publications) made through R&D play a pivotal role for national economic growth. National governments encourage academia-industry cooperation and thereby pursue continuous development of science technology and innovation. Increasing R&D-related investments and manpower are crucial for national industrial development, but evidence of poor performance in business performance, efficiency, and effectiveness has recently been found in Korea. This study evaluates performance efficiency of the 6T sector (Information Technology, Bio Technology, Nano Technology, Space Technology, Environment Technology, Culture Technology), which is considered a high-potential promising industry for the next generation growth and currently occupies two thirds of the national R&D projects. The study measures the relative efficiency of R&D in a comparative perspective by employing the Data Envelopment Analysis (DEA) method. The result reveals overall low efficiency in basic R&D (0.2112), applied R&D (0.2083), development R&D (0.2638), and others (0.0641), confirming that economic performance and efficiency were relatively poor compared to production efficiency. Efficient R&D needs policy makers to create strategies that can increase overall efficiency by improving productivity performance and quality while increasing economic performance.

• 대한의생명과학회지
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• 제25권4호
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• pp.398-406
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• 2019

Cancer immunotherapy using gene-modified tumor cells is safe and customized cancer treatment method. In this study, we made gene-modified tumor cells by transferring costimulatory molecules, 4-1BBL and OX40L, into tumor cells using lentivirus vector, and identified anti-cancer effect of gene-modified tumor cells in CT26 mouse colorectal tumor model. We construct pLVX-puro-4-1BBL, -OX40L vector for lentivirus production and optimized the transfection efficiency and transduction efficiency. The transfection efficiency is maximal at DNA:cationic polymer = 1:0.5 and DNA 2 ㎍ for lentivirus production. Then, the lentiviral including 4-1BBL and OX40L was used to deliver CT26 mouse tumor cells to establish optimal delivery conditions according to the amount of virus. The transduction efficiency is maximal at 500 μL volume of lentiviral stock without change in cell shape or growth rate. CT26-4-1BBL, CT26-OX40L significantly inhibited the tumor growth compare with CT26-WT or CT26-β-gal cell line. These data showed the possibility the use of genetically modified tumor cells with costimulatory molecule as cancer immunotherapy agent.