• Title/Summary/Keyword: marginal effects

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Fundamental Studies for the Breeding of Marine Algae 3. Effects of Plant Hormones on the Growth of Porphyra-fronds (해조의 육종을 위한 기초적 연구 3. 김 엽체에 미치는 식물호르몬의 생장효과)

  • KIM Joong-Rae;JO Young-Won;HAN Chang-Yeal;LEE Man-Sang
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.14 no.2
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    • pp.79-85
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    • 1981
  • As one of the fundamental studies for the breeding of marine algae, the effects of several plant hormones (IAA, Gibberellin, 2.4-D, NAA, Kinetin) on the growth of Porphyra-fronds, P. tenera Kjell. form tamatsuensis Miura, were investigated from January 21 to February 21 1981. The fronds used for the experiment were dissected out at $25mm^2$ size, and cultured in modified Provasoli's ESP medium supplemented with various concentrations of each plant growth regulators. The culture was kept under constant water temperature of $5^{\circ}C$ in 14 hrs. photoperiod and illuminated with 2,400 lux by fluorescent light. Based on the results of first experiment, the culture of fronds for the secondary experiment was carried out at $5^{\circ}C\;and\;10^{\circ}C$ in medium containing various levels of Kinetin from April 6 to 24, and compared the growth of two groups at each concentrations with each other, The results obtained are summarized as follows : (1) The best growth efficiencies were observed at 5.0mg/1 of each plant hormones except Gibberellin. Among them, the highest growth-rate was $312.5\%\;(345.3\%\;in\;frond\;size)$ in contrast with control at 5.0mg/1 of Kinetin, and was followed by $257.5\%\;(236.1\%)$ in 2.4-D,$166.7\%(147.6\%)$ in IAA and $141.7\%\;(167.7\%)$ in NAA, but that in Gibberellin was $247.9\%(241.9\%)$ at 10.0mg/l. (2) Especially, the fronds cultured at 5.0mg/1 of Kinetin were deep black-brown in colour, and had vivid, healthy chloroplasts in their all cells. On the contrary, the fronds cultured in other media were discoloured to light black-brown or green-drown, and almost all cells were vacuolated or shrunk gradually into death.(3) There was an obvious difference between the best growth-rates of the fronds cultured at 5.0mg/l of Kinetin at $5^{\circ}C$ and those at $10^{\circ}C$. The former was $366.7\%$, the latter $318.8\%$ but the difference was little at lower concentrations. (4) Many abnormal cells grown up to $25.0-27.5\mu$ in diameter were found among the marginal cells of fronds which showed the best growth in Kinetin, and the fronds wire $41.0-42.0\mu$ in thickness which was thicker by $10.0\mu$ or so than the others. (5) In two fronds at 1.0mg/1 of Kinetin cell-divisions were observed, which might developed into antheridium, but it was doubtful whether due to the efficiency of Kinetin.

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Value of Information Technology Outsourcing: An Empirical Analysis of Korean Industries (IT 아웃소싱의 가치에 관한 연구: 한국 산업에 대한 실증분석)

  • Han, Kun-Soo;Lee, Kang-Bae
    • Asia pacific journal of information systems
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    • v.20 no.3
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    • pp.115-137
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    • 2010
  • Information technology (IT) outsourcing, the use of a third-party vendor to provide IT services, started in the late 1980s and early 1990s in Korea, and has increased rapidly since 2000. Recently, firms have increased their efforts to capture greater value from IT outsourcing. To date, there have been a large number of studies on IT outsourcing. Most prior studies on IT outsourcing have focused on outsourcing practices and decisions, and little attention has been paid to objectively measuring the value of IT outsourcing. In addition, studies that examined the performance of IT outsourcing have mainly relied on anecdotal evidence or practitioners' perceptions. Our study examines the contribution of IT outsourcing to economic growth in Korean industries over the 1990 to 2007 period, using a production function framework and a panel data set for 54 industries constructed from input-output tables, fixed-capital formation tables, and employment tables. Based on the framework and estimation procedures that Han, Kauffman and Nault (2010) used to examine the economic impact of IT outsourcing in U.S. industries, we evaluate the impact of IT outsourcing on output and productivity in Korean industries. Because IT outsourcing started to grow at a significantly more rapid pace in 2000, we compare the impact of IT outsourcing in pre- and post-2000 periods. Our industry-level panel data cover a large proportion of Korean economy-54 out of 58 Korean industries. This allows us greater opportunity to assess the impacts of IT outsourcing on objective performance measures, such as output and productivity. Using IT outsourcing and IT capital as our primary independent variables, we employ an extended Cobb-Douglas production function in which both variables are treated as factor inputs. We also derive and estimate a labor productivity equation to assess the impact of our IT variables on labor productivity. We use data from seven years (1990, 1993, 2000, 2003, 2005, 2006, and 2007) for which both input-output tables and fixed-capital formation tables are available. Combining the input-output tables and fixed-capital formation tables resulted in 54 industries. IT outsourcing is measured as the value of computer-related services purchased by each industry in a given year. All the variables have been converted to 2000 Korean Won using GDP deflators. To calculate labor hours, we use the average work hours for each sector provided by the OECD. To effectively control for heteroskedasticity and autocorrelation present in our dataset, we use the feasible generalized least squares (FGLS) procedures. Because the AR1 process may be industry-specific (i.e., panel-specific), we consider both common AR1 and panel-specific AR1 (PSAR1) processes in our estimations. We also include year dummies to control for year-specific effects common across industries, and sector dummies (as defined in the GDP deflator) to control for time-invariant sector-specific effects. Based on the full sample of 378 observations, we find that a 1% increase in IT outsourcing is associated with a 0.012~0.014% increase in gross output and a 1% increase in IT capital is associated with a 0.024~0.027% increase in gross output. To compare the contribution of IT outsourcing relative to that of IT capital, we examined gross marginal product (GMP). The average GMP of IT outsourcing was 6.423, which is substantially greater than that of IT capital at 2.093. This indicates that on average if an industry invests KRW 1 millon, it can increase its output by KRW 6.4 million. In terms of the contribution to labor productivity, we find that a 1% increase in IT outsourcing is associated with a 0.009~0.01% increase in labor productivity while a 1% increase in IT capital is associated with a 0.024~0.025% increase in labor productivity. Overall, our results indicate that IT outsourcing has made positive and economically meaningful contributions to output and productivity in Korean industries over the 1990 to 2007 period. The average GMP of IT outsourcing we report about Korean industries is 1.44 times greater than that in U.S. industries reported in Han et al. (2010). Further, we find that the contribution of IT outsourcing has been significantly greater in the 2000~2007 period during which the growth of IT outsourcing accelerated. Our study provides implication for policymakers and managers. First, our results suggest that Korean industries can capture further benefits by increasing investments in IT outsourcing. Second, our analyses and results provide a basis for managers to assess the impact of investments in IT outsourcing and IT capital in an objective and quantitative manner. Building on our study, future research should examine the impact of IT outsourcing at a more detailed industry level and the firm level.

Factors Influencing the Adoption of Location-Based Smartphone Applications: An Application of the Privacy Calculus Model (스마트폰 위치기반 어플리케이션의 이용의도에 영향을 미치는 요인: 프라이버시 계산 모형의 적용)

  • Cha, Hoon S.
    • Asia pacific journal of information systems
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    • v.22 no.4
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    • pp.7-29
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    • 2012
  • Smartphone and its applications (i.e. apps) are increasingly penetrating consumer markets. According to a recent report from Korea Communications Commission, nearly 50% of mobile subscribers in South Korea are smartphone users that accounts for over 25 million people. In particular, the importance of smartphone has risen as a geospatially-aware device that provides various location-based services (LBS) equipped with GPS capability. The popular LBS include map and navigation, traffic and transportation updates, shopping and coupon services, and location-sensitive social network services. Overall, the emerging location-based smartphone apps (LBA) offer significant value by providing greater connectivity, personalization, and information and entertainment in a location-specific context. Conversely, the rapid growth of LBA and their benefits have been accompanied by concerns over the collection and dissemination of individual users' personal information through ongoing tracking of their location, identity, preferences, and social behaviors. The majority of LBA users tend to agree and consent to the LBA provider's terms and privacy policy on use of location data to get the immediate services. This tendency further increases the potential risks of unprotected exposure of personal information and serious invasion and breaches of individual privacy. To address the complex issues surrounding LBA particularly from the user's behavioral perspective, this study applied the privacy calculus model (PCM) to explore the factors that influence the adoption of LBA. According to PCM, consumers are engaged in a dynamic adjustment process in which privacy risks are weighted against benefits of information disclosure. Consistent with the principal notion of PCM, we investigated how individual users make a risk-benefit assessment under which personalized service and locatability act as benefit-side factors and information privacy risks act as a risk-side factor accompanying LBA adoption. In addition, we consider the moderating role of trust on the service providers in the prohibiting effects of privacy risks on user intention to adopt LBA. Further we include perceived ease of use and usefulness as additional constructs to examine whether the technology acceptance model (TAM) can be applied in the context of LBA adoption. The research model with ten (10) hypotheses was tested using data gathered from 98 respondents through a quasi-experimental survey method. During the survey, each participant was asked to navigate the website where the experimental simulation of a LBA allows the participant to purchase time-and-location sensitive discounted tickets for nearby stores. Structural equations modeling using partial least square validated the instrument and the proposed model. The results showed that six (6) out of ten (10) hypotheses were supported. On the subject of the core PCM, H2 (locatability ${\rightarrow}$ intention to use LBA) and H3 (privacy risks ${\rightarrow}$ intention to use LBA) were supported, while H1 (personalization ${\rightarrow}$ intention to use LBA) was not supported. Further, we could not any interaction effects (personalization X privacy risks, H4 & locatability X privacy risks, H5) on the intention to use LBA. In terms of privacy risks and trust, as mentioned above we found the significant negative influence from privacy risks on intention to use (H3), but positive influence from trust, which supported H6 (trust ${\rightarrow}$ intention to use LBA). The moderating effect of trust on the negative relationship between privacy risks and intention to use LBA was tested and confirmed by supporting H7 (privacy risks X trust ${\rightarrow}$ intention to use LBA). The two hypotheses regarding to the TAM, including H8 (perceived ease of use ${\rightarrow}$ perceived usefulness) and H9 (perceived ease of use ${\rightarrow}$ intention to use LBA) were supported; however, H10 (perceived effectiveness ${\rightarrow}$ intention to use LBA) was not supported. Results of this study offer the following key findings and implications. First the application of PCM was found to be a good analysis framework in the context of LBA adoption. Many of the hypotheses in the model were confirmed and the high value of $R^2$ (i.,e., 51%) indicated a good fit of the model. In particular, locatability and privacy risks are found to be the appropriate PCM-based antecedent variables. Second, the existence of moderating effect of trust on service provider suggests that the same marginal change in the level of privacy risks may differentially influence the intention to use LBA. That is, while the privacy risks increasingly become important social issues and will negatively influence the intention to use LBA, it is critical for LBA providers to build consumer trust and confidence to successfully mitigate this negative impact. Lastly, we could not find sufficient evidence that the intention to use LBA is influenced by perceived usefulness, which has been very well supported in most previous TAM research. This may suggest that more future research should examine the validity of applying TAM and further extend or modify it in the context of LBA or other similar smartphone apps.

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A Study on the Service Quality Improvement by Kano Model & Weighted Potential Customer Satisfaction Index (Kano 모델 및 가중 PCSI를 통한 서비스품질 개선에 관한 연구)

  • Kim, Sang-Cheol
    • Journal of Distribution Science
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    • v.8 no.4
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    • pp.17-23
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    • 2010
  • The Banking industry is expanding rapidly. To keep the competitive advantages, participating companies concentrate their resource to provide the distinguishable services by increasing the service quality. This study is to find that how three kinds of service quality(process, output, and service environment) affect on the customer satisfaction. In this paper, WPCSI (Weighted Potential Customer Satisfaction Index) was developed using Kano model and PCSI. Kano's model of service quality classification was used to improve customer satisfaction, customer satisfaction index was calculated. Customer satisfaction index was calculated using the existing potential for improving customer satisfaction index (PCSI Index) to complement the limitations of the weighted potential improve customer satisfaction index (WPCSI) were used. Analysis using PCSI improve the quality of service levels may be useful in assessing. However, this figure is a marginal degree of importance on customers and quality characteristics have been overlooked but has its problems. A service provided to customers with some important differences depending on the interpretation of the scope for improvement is to be classified. In other words, the level of customer satisfaction and the satisfaction of the current difference between the comparison factor for the company to provide information about the priority of the improvement was not significant. Companies are also considered important that the customer does not consider the uniform quality of service provided can be fallible. In this study, the weighted potential to improve it improve customer satisfaction index (WPCSI) proposed a new customer satisfaction index. This is for customers to recognize the importance of quality characteristics by weighting factors, to identify practical and improved priority to provide more useful information than has been. Weighted potentially improve customer satisfaction index (WPCSI) presented in this study by the customers aware of the importance of considering the quality factor is an exponent. The results, 'Employees' working ability', 'provided the desired service level', 'staff to handle this task quickly enough' to the customer of the factors had significant effects on satisfaction are met. On the other hand 'aggressiveness on the product description of employees', 'service environment as a whole, beautiful enough to' meet and shows no significant difference between satisfaction. But 'aggressiveness on the product description of employees' and reverse (逆) were attributable to the quality. Small dogs and overly aggressive products that encourage the customer dissatisfaction that can result in widening should be careful because the quality factor can be said. As a result, WPCSI is more effect to find critical factors which can affect customer satisfaction than PCSI. After that, we discuss effects and advantages of customer satisfaction using WPCSI. This study, along with these positive aspects, the limitations are implied. First, this study directly to the bank so that I could visit any other way for customers, utilizing the Internet or mobile to take advantage of the respondents were excluded from the analysis. Second, in survey questionnaires can help improve understanding of the measures will be taken. In addition to the survey targeted mainly focused on Seoul, according to a sample, so sampling can cause problems is the viscosity revealed intends.

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Inhibitory Effect of Scopoletin Isolated from Sorbus commixta on TNF-α-Induced Inflammation in Human Vascular Endothelial EA.hy926 Cells through NF-κB Signaling Pathway Suppression (마가목 수피에서 분리한 scopoletin의 EA.hy926 혈관내피세포에서 NF-κB 신호전달을 통한 TNF-α로 유도된 혈관염증 저해 효과)

  • Kang, Hye Ryung;Kim, Hyo Jung;Kim, Bomi;Kim, Sun-Gun;So, Jai-Hyun;Cho, Soo Jeong;Kwon, Hyun Sook
    • Journal of Life Science
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    • v.30 no.4
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    • pp.343-351
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    • 2020
  • Sorbus commixta Hedl. has traditionally been used as a remedy for cough, asthma, and other bronchial disorders. In this study, three major triterpenoids-lupeol, β-sitosterol, and ursolic acid and a coumarin, scopoletin, were isolated from a CHCl3-soluble fragment of the bark of S. commixta. Their structures were identified by spectroscopic analyses, including mass spectrometry (MS), 1D-, and 2D- nuclear magnetic resonance spectroscopy (NMR), as well as by comparing the data with data reported in the literature. Scopoletin was isolated from this plant for the first time. It is a nutraceutical compound contained in many plants that has been reported to exert diverse biological activities, including anti-inflammatory effects. This study examined the inhibitory effect of scopoletin on TNF-α-induced vascular endothelial inflammation. Unlike the marginal impact of other compounds against low-density lipoprotein (LDL) oxidation and vascular endothelial inflammation, scopoletin showed remarkable activity on LDL oxidation (IC50 = 10.2 μM) and exerted vascular anti-inflammatory effects in EA.hy926 human endothelial cells activated by TNF-α. It suppressed the expression of adhesion molecules, such as ICAM-1, VCAM-1, and E-selectin, and blocked the adhesion between THP-1 monocytes and EA. hy926 endothelial cells. It also inhibited TNF-α-induced NF-κB translocation from the cytosol to the nucleus. Moreover, IκBα phosphorylation, which was increased by TNF-α treatment, was reduced after treatment with scopoletin. Thus, scopoletin inhibited TNF-α-induced vascular inflammation in endothelial cells by suppressing the NF-κB signaling pathway. These results demonstrate that owing to its anti-inflammatory activity in the vascular endothelium, scopoletin has the potential to inhibit atherosclerosis development.

Determinants of Consumer Responses to Retail Out-of-Stocks (점포내 품절상황에서 소비자 반응행동유형별 결정요인)

  • Chun, Dal-Young;Choi, Jong-Rae;Joo, Young-Jin
    • Journal of Distribution Research
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    • v.16 no.4
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    • pp.29-64
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    • 2011
  • Overview of Research: Product availability is one of important competences of store to fulfill consumer needs. If stock-outs which means a product what consumer wants to buy is not available occurs, consumer will face decision-making uncertainty that leads to consumer's negative responses such as consumer dissatisfaction on store. Stockouts was much studied in the field of academia as well as practice in other countries. However, stock-outs has not been researched at all in Marketing and/or Distribution area in Korea. The main objectives of this study are to find out determinants of consumer responses such as Substitute, Delay, and Leave(SDL) when consumer encounters out-of-stock situation and then to examine the effects of these factors on consumer responses. Specifically, this study focuses on situational characteristics(e.g., purchase urgency and surprise), store characteristics (e.g., product assortment and store convenience), and consumer characteristics (e.g., brand loyalty and store loyalty). Then, this study empirically investigates relationships these factors with consumers behaviors such as product substitution, purchase delay, and store switching.

    shows the research model of this study. To accomplish above-mentioned research objectives, the following ten hypotheses were proposed and verified : ${\bullet}$ H 1 : When out-of-stock situation occurs, purchase urgency will increase product substitution but will decrease purchase delay and store switching among consumer responses. ${\bullet}$ H 2 When out-of-stock situation occurs, surprise will decrease product substitution and purchase delay but will Increase store switching among consumer responses. ${\bullet}$ H 3 : When out-of-stock situation occurs, purchase quantities will increase product substitution and store switching but will decrease purchase delay among consumer responses. ${\bullet}$ H 4 : When out-of-stock situation occurs, pre-purchase plan will decrease product substitution but will increase purchase delay and store switching among consumer responses. ${\bullet}$ H 5 : When out-of-stock situation occurs, product assortment will increase product substitution but will decrease purchase delay and store switching among consumer responses. ${\bullet}$ H 6 : When out-of-stock situation occurs, competitive store price image will increase product substitution and purchase delay but will decrease store switching among consumer responses. ${\bullet}$ H 7 : When out-of-stock situation occurs, store convenience will increase product substitution but will decrease purchase delay and store switching among consumer responses. ${\bullet}$ H 8 : When out-of-stock situation occurs, salesperson services will increase product substitution but will decrease purchase delay and store switching among consumer responses. ${\bullet}$ H 9 : When out-of-stock situation occurs, brand loyalty will decrease product substitution but will increase purchase delay and store switching among consumer responses. ${\bullet}$ H 10 When out-of-stock situation occurs, store loyalty will increase product substitution and purchase delay but will decrease store switching among consumer responses. Analysis: Data were collected from 353 respondents who experienced out-of-stock situations in various store types such as large discount stores, supermarkets, etc. Research model and hypotheses were verified using multinomial logit(MNL) analysis. Results and Implications: is the estimation results of l\1NL model, and
    shows the marginal effects for each determinant to consumer's responses(SDL). Significant statistical results were as follows. Purchase urgency, purchase quantities, pre-purchase plan, product assortment, store price image, brand loyalty, and store loyalty were turned out to be significant determinants to influence consumer alternative behaviors in case of out-of-stock situation. Specifically, first, product substitution behavior was triggered by purchase urgency, surprise, purchase quantities, pre-purchase plan, product assortment, store price image, brand loyalty, and store loyalty. Second, purchase delay behavior was led by purchase urgency, purchase quantities, and brand loyalty. Third, store switching behavior was influenced by purchase urgency, purchase quantities, pre-purchase plan, product assortment, store price image, brand loyalty, and store loyalty. Finally, when out-of-stock situation occurs, store convenience and salesperson service did not have significant effects on consumer alternative responses.

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  • Effect of $\beta$-glucan Extracted from Youngji Mushroom on the Growth Performance of Weaning Pigs (영지버섯에서 추출한 $\beta$-glucan 이 자돈의 생산능력에 미치는 영향)

    • Kim, Jong-Duk;Shim, Keum-Seob;Choi, Nag-Jin;Kim, Ji-Hoon;Kim, Yong-Hyun;Kwon, Hyun-Jung;Kim, Sun-Ki;Han, Man-Deuk
      • Korean Journal of Organic Agriculture
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      • v.18 no.3
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      • pp.401-418
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      • 2010
    • This experiment was selected a $\beta$-glucan producing mushroom strain and developed industrial media, and used to $\beta$-glucan as an alternative for antibiotics in weaned pigs. Yields of mycelial biomass and extracellular $\beta$-glucan from Youngji (Ganoderma lucidum) mushroom was 8.52g/L and 4.49g/L respectively. Also, we prepared optimum formula for mushroom cultivations. A total of 144 pigs ($8.6{\pm}0.9$ kg average body weight, weaned $20{\pm}3$ days of age) were allotted to 4 different treatment groups and replicated 4 times with 8 pigs per replicate in randomized complete block design. Treatments were T1) NC (negative control, basal diet), T2) PC (positive control, basal diet+0.255% antibiotics), T3) NC+0.2% $\beta$-glucan and T4) PC+0.2% $\beta$-glucan. The T2 and T4 treatments were significantly higher in feed efficiency by antibiotics group (p<0.05), however, there was no significant differences in terms of average daily gain (ADG) and average daily feed intake (ADFI) during phase I (0~14 days). In phase II (15~28 days), Pigs fed with antibiotics and $\beta$-glucan (T4) had greater ADG than other treatments (p<0.05), while no differences were observed in ADFI and feed efficiency. During the whole experiment period, the ADG of T4 treatment was higher than other treatments. Pigs fed with $\beta$-glucan (T3 and T4) had greater diarrhea score and moisture content than other treatments (p<0.05). Pigs fed with $\beta$-glucan (T3 and T4) had greater moisture content than other treatments (p<0.05). However, there was no significant differences in diarrhea score and mortality of weaned pigs. There was marginal reductions in feed cost measured feed cost per weight gain used in antibiotics and $\beta$-glucan added diet during phase I. In the second phase, the treatment supplemented with antibiotics had a significantly lower feed cost per weight gain compared to the other treatments. The results from these experiments suggests that $\beta$-glucan is likely able to improve the growth performance, and reduce feed cost although they do not have similar effects like antibiotics in weaning pigs.

    The Stakeholder's Response and Future of Mountain Community Development Program in Rep. of Korea (한국 산촌개발사업에 대한 이해관계자의 의식과 향후 발전방안)

    • Yoo, Byoung Il;Kim, So Heui;Seo, Jeong-Weon
      • Journal of Korean Society of Forest Science
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      • v.94 no.4 s.161
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      • pp.214-225
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      • 2005
    • The mountain village development program in Korea started in the mountain villages, the 45.9% of total land and one of the typical marginal region, from 1995 to achieve the equilibrium development of national land and the sustainable mountain development in Chapter 13 in Agenda 21, and it has been accelerated to increase the happiness and the quality of life of mountain community residents through the expansion by province and the improvement of related laws and regulations. This study has been aimed to analyze the response of main stakeholder's -mountain village residents and local government officials - on mountain villages development, and to provide the future plan as community development. The survey and interview data were collected from the mountain villages which already developed 59 villages and developing 15 villages in 2003. The mountain village development program has achieved the positive aspects as community development plan in the several fields, - the voluntary participation of residents, the establishment of self-support spirit as the democratic civilians, the development of base of income increasement, the creation of comfortable living environment, the equilibrium development with the other regions. Especially the mountain residents and local government officials both highly satisfy with the development of base of income increasement and the creation of comfortable living environment which are the main concerns to both stakeholder. However through the mountain development program, it is not satisfied to increase the maintenance of local community and the strengthening of traditional value of mountain villages. Also to improve the sustainable income improvement effects, it is necessary to develop the income items and technical extension which good for the each region. In the decentralization era, it is necessary for local government should have the more active and multilateral activities for these. With this, the introduction of methods which the mountain community people and the local government officials could co-participate in the mountain villages' development from the initial stages and the renovation of related local government organizations and the cooperatives will be much helpful to the substantiality of mountain development program. Also it is essential for the assistance of central government to establish the complex plan and the mountain villages network for all mountain area and the exchange of information, the education and training of mountain villages leader who are the core factor for the developed mountain villages maintenance, the composition of national mountain villages representatives. In case the development proposals which based on the interests of the main stakeholder's on mountain community could be positively accepted, then the possibility of the mountain village development as one of community development will be successfully improved in future.

    A Study on the Installation of Groyne using Critical Movement Velocity and Limiting Tractive Force (이동한계유속과 한계소류력을 활용한 수제 설치에 관한 연구)

    • Kim, Yeong Sik;Park, Shang Ho;An, Ik Tae;Choo, Yeon Moon
      • Journal of Wetlands Research
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      • v.22 no.3
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      • pp.194-199
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      • 2020
    • Unlike in the past, the world is facing water shortages due to climate change and difficulties in simultaneously managing the risks of flooding. The Four Major Rivers project was carried out with the aim of realizing a powerful nation of water by managing water resources and fostering the water industry, and the construction period was relatively short compared to the unprecedented scale. Therefore, the prediction and analysis of how the river environment changes after the Four Major Rivers Project is insufficient. Currently, part of the construction section of the Four Major Rivers Project is caused by repeated erosion and sedimentation due to the effects of sandification caused by large dredging and flood-time reservoirs, and the head erosion of the tributaries occurs. In order to solve these problems, the riverbed maintenance work was installed, but it resulted in erosion of both sides of the river and the development of new approaches and techniques to keep the river bed stable, such as erosion and excessive sedimentation, is required. The water agent plays a role of securing a certain depth of water for the main stream by concentrating the flow so much in the center and preventing levee erosion by controlling the flow direction and flow velocity. In addition, Groyne products provide various ecological environments by forming a natural form of riverbeds by inducing local erosion and deposition in addition to the protection functions of the river bank and embankment. Therefore, after reviewing the method of determining the shape of the Groyne structure currently in use by utilizing the mobile limit flow rate and marginal reflux force, a new Critical Movement Velocity(${\bar{U}}_d$) and a new resistance coefficient formula considering the mathematical factors applicable to the actual domestic stream were developed and the measures applicable to Groyne installation were proposed.

    A Study on Optimum Rate of Cattle Slurry Application for Forage Production using Idled Arable Land. I. The effect of applying time of cattle slurry and fertilization added mineral nitrogen on dry matter yield in Orchardgrass (유휴지에서 조사료 생산을 위한 적정 가축분뇨의 시용에 관한 연구 I. 액상구비의 시용시기와 무기태 질소의 첨가가 Orchardgrass의 건물수량에 미치는 영향)

    • Jo, Ik Hwan
      • Journal of the Korea Organic Resources Recycling Association
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      • v.2 no.2
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      • pp.65-75
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      • 1994
    • The aim of this experiment was to investigate the effects of applying time of cattle slurry and fertilizing added mineral nitrogen on dry matter yield of orchardgrass and also to estimate proper levels of fertilizing nitrogen when idled arable land rapidly increased these days, which was used for the production of Orchardgrass. The results were as follows. 1. The annual yields of dry matter were produced 5.62~6.67 ton per ha when cattle slurry applied at rates of $30m^3$(average mineral fertilizer equivalent to 120kg) per ha in different dressing times. Those were higher 0.60~1.65 ton or 0.16 ton per ha than the yields from non-fertilizing or phosphrous and potassium fertilizing. 2. Relative yields of annual dry matter from mineral nitrogen fertilization of 120kg per ha were 142~146% in comparsion with control plots(cattle slurry plot or phosphrous and potassium plot). On the other hand, those of cattle slurry application were 112~133% in comparion with non-fertilizing plot. 3. The efficiencies of nitrogen on dry matter yield(kg DM/kg N) were 5.0~13.8 DM kg/N kg when cattle slurry applied to Orchardgrass at rates of $30m^3$(average mineral fertilizer equivalent to 120kg) per ha, and were 21.3~23.1kg DM/kg N at the same level fertilization of mineral nitrogen. 4. On the condition of this study, mineral nitrogen were fertilized after applying cattle slurry at rates of $30m^3$(average mineral fertilizer equivalent to 120kg) per ha in order to minimize chemical fertilizer and increase the potential production of Orchardgrass. At this situation, marginal dry matter yields of 8.48~8.63 ton per ha were obtained as the level of economic even point goint when mineral nitrogen fertilization is between 119.4 and 133.3kg per ha. It was possible to obtain the maximal dry matter yield(8.98 tons/ha) with fertilization of 202.8kg N/ha.

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