• PNF and Movement
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• v.19 no.3
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• pp.423-433
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• 2021

Purpose: Proprioceptive neuromuscular facilitation (PNF) is a method for promoting functional movements by facilitating neuromuscular responses through the stimulation of proprioceptors in the body using spiral and diagonal patterns. Irradiation, a basic principle of PNF, is a phenomenon in which the muscle activity of a body part caused by resistance is increased or spread into muscles in other parts via their connected muscles. Resistance training can be divided by body alignment into closed and open chain exercises. Methods: In this study, 19 healthy men in their 20s and 30s were selected as subjects. They performed PNF hip flexion, abduction, and internal rotation motions on their dominant side in an open chain exercise posture in which the nondominant sole was away from the wall, and in a closed chain exercise posture in which the sole was fixed to the wall. The nondominant leg's muscle activity was measured while resistance was maintained with applied pressure at 0%, 25%, 50%, 75%, and 100% of the maximum muscle strength in the last range of motions. A two-way analysis of variance (ANOVA) was conducted for a comparative analysis of the contralateral leg's muscle activity according to the chain exercise postures and the intensity of resistance intensity during PNF hip flexion, abduction, and internal rotation. In addition, an independent sample T-test was conducted for a comparative analysis of each chain exercise posture according to the intensity of resistance. A one-way ANOVA and a Scheffe post-hoc test were also performed to analyze the contralateral leg's muscle activity according to the intensity of resistance in the closed and open chain exercise postures. Results: Results of the two-way ANOVA found that the gluteus medius and the biceps femoris had statistically significant differences in both the chain exercise postures and resistance intensity (p<0.05), and that the vastus medialis and the gastrocnemius did not exhibit statistically significant differences in the chain exercise postures (p>0.05) but showed statistically significant differences in resistance intensity (p<0.05). As a result of the independent sample T-test, the application of the PNF hip flexion-abduction-internal rotation pattern led to a statistically significant difference in the contralateral gluteus medius during the closed chain exercise posture (p<0.05). According to the results of the one-way ANOVA and the Scheffe post-analysis, statistically significant differences were observed in the gluteus medius at 50%, biceps femoris at 75%, vastus medialis at 100%, and gastrocnemius at 100% during the closed chain exercise posture based on a resistance intensity of 0% (p<0.05). In the open chain exercise posture, statistically significant differences were found in the gluteus medius at 50%, biceps femoris at 50%, and vastus medialis at 75% based on the resistance intensity of 0% (p<0.05). In the same posture, there was no significant difference in the gastrocnemius's resistance intensity (p>0.05). Conclusion: When the PNF leg pattern is applied, each muscle requires effective chain exercise postures and resistance intensity to generate the contralateral leg muscle's irradiation.

• Korean Journal of Remote Sensing
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• v.37 no.6_1
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• pp.1559-1572
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• 2021

The response of vegetation under the crop stress condition was evaluated using structural, biochemical, and physiological vegetation indices based on unmanned aerial vehicle (UAV) images and field-spectrometer data. A high concentration of herbicide was sprayed at the different growth stages of garlic to process crop stress, the above ground dry matter of garlic at experimental area (EA) decreased about 46.2~84.5% compared to that at control area. The structural vegetation indices clearly responded to these crop damages. Spectral reflectance at near-infrared wavelength consistently decreased at EA. Most biochemical vegetation indices reflected the crop stress conditions, but the meaning of physiological vegetation indices is not clear due to the effect of vinyl mulching. The difference of the decreasing ratio of vegetation indices after the herbicide spray was 2.3% averagely in the case of structural vegetation indices and 1.3~4.1% in the case of normalization-based vegetation indices. These results meant that appropriate vegetation indices should be utilized depending on the types of crop stress and the cultivation environment and the normalization-based vegetation indices measured from the different spatial scale has the minimized difference.

• Journal of the Korean Society for Library and Information Science
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• v.55 no.4
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• pp.5-22
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• 2021

This study aimed to understand how people perceive the transition from offline to online classes at universities during the COVID-19 pandemic. To achieve the goal, we collected tweets related to online classes on Twitter and performed sentiment and time series topic analysis. We have the following findings. First, through the sentiment analysis, we found that there were more negative than positive opinions overall, but negative opinions had gradually decreased over time. Through exploring the monthly distribution of sentiment scores of tweets, we found that sentiment scores during the semesters were more widespread than the ones during the vacations. Therefore, more diverse emotions and opinions were showed during the semesters. Second, through time series topic analysis, we identified five main topics of positive tweets that include class environment and equipment, positive emotions, places of taking online classes, language class, and tests and assignments. The four main topics of negative tweets include time (class & break time), tests and assignments, negative emotions, and class environment and equipment. In addition, we examined the trends of public opinions on online classes by investigating the changes in topic composition over time through checking the proportions of representative keywords in each topic. Different from the existing studies of understanding public opinions on online classes, this study attempted to understand the overall opinions from tweet data using sentiment and time series topic analysis. The results of the study can be used to improve the quality of online classes in universities and help universities and instructors to design and offer better online classes.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.4
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• pp.85-99
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• 2021

Due to the continuous unemployment problem, the number of jobs is gradually decreasing, and entrepreneurship is emerging as an alternative. This is because, despite the government operating various start-up support programs to build a start-up-friendly culture, young entrepreneurs cannot endure the valley of death and disappear. Therefore, through this study, we intend to provide implications by analyzing the impact on Entrepreneurial satisfaction, which is essential for continuously running a business, and life satisfaction, which can act as a social awareness. This study was conducted with 573 non-wage workers who belonged to the founders among the participants of the 'College Graduation Occupational Migration Path Survey(GOMS)' survey provided by the Korea Employment Information Service. In order to analyze the relationship between entrepreneurial competency and job fit, Entrepreneurial satisfaction, and life satisfaction, the analysis was conducted using the SPSS 23.0 program. The main research results are summarized as follows. First, entrepreneurial competency has a positive effect on Entrepreneurial satisfaction and life satisfaction. Second, job fit indicates a moderating role in the relationship between entrepreneurial competency and Entrepreneurial satisfaction. Third, start-up satisfaction appears to have a partial mediating role in the relationship between entrepreneurial competency and life satisfaction. Fourth, as a result of analyzing the difference between groups according to the type of start-up(single/partnership), the group that worked together showed higher Entrepreneurial satisfaction and life satisfaction. The main implications of this study are: First, in order to increase the Entrepreneurial satisfaction and life satisfaction of university graduates who are the subject of the study, it will be necessary to design a program that can diagnose and enhance the entrepreneurial competency of students at the university level. Second, entrepreneurial competency is a basic intrinsic factor that founders must have, and it should act as an important evaluation factor when selecting founders for support programs from start-up support organizations as well as founders. Third, it is necessary to maintain mutual trust by documenting problems (positions, wages, management rights, distribution of profits, etc.) that may occur in joint ventures with objective data. Fourth, it is necessary to establish an environment in which the MZ generation, armed with the challenging spirit and creativity, can continue to take on challenges even if they fail.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.3
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• pp.190-200
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• 2021

The heading response of rice varieties, originated from South Korea, North Korea, and northern China, was examined under the temperature and day-length conditions of 10 low-temperature regions in North Korea. When 30-day-old broadcast tray-raised seedlings (BS) were used, only one or a few varieties reached the heading stage within the safe marginal heading date (SMHD) under the Hamhung, Pyonggang, Huichon, and Kanggye conditions. In the Yangdok and Sinpo environments, no varieties reached heading until SMHD. The South Korean varieties that reached the heading stage between SMHD and late marginal heading date (LMHD) were Jinbuol, Baegilmi, Joun, Jopum, Jinok, Jopyeong, Sanhomi, and Odae for the Hamhung, Pyonggang, Huichon, and Kanggye; Joun for Sinpo; and none for Yangdok, Kimchaek, Sonbong, and Chunggang environments. The number of days to heading (DTH) was positively correlated among all 10 regions. Reduced DTH in the 30-day-old pot tray-raised seedlings (PS), compared to BS, was not consistent with varieties and regions. Reduced DTH in PS, compared to BS, was the largest in Jinok and Sonbong9 among the South and North Korean varieties, respectively, whereas it was small in the northern Chinese varieties. The South Korean varieties that headed until SMHD in PS were Jinok for the Hamhung, Pyonggang, Yangdok, Sinpo, and Kanggye environments; and Jinbuol, Jopum, and Jinok for the Huichon condition. In the Kimchaek and Chunggang conditions, Jinok reached the heading stage within LMHD. With the use of PS for some responsive varieties such as Jinok, varietal adaptability could be improved to the conditions of low-temperature regions in North Korea. None of the PS or BS among the tested varieties reached the heading stage until LMHD for the Chongjin and Sonbong conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.3
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• pp.256-264
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• 2021

Rapeseed (Brassica napus L.) is generally sown in late autumn and harvested in early summer in Korea, however, spring cultivation has also been attempted in some areas because frequent climate changes induce reducing productivity. Therefore, there is a need for a transplanting technology that is relatively easy to control of cropping season according to changes in cultivation conditions. In this study, to find out the optimal characteristics of seedlings for machine transplanting of spring cultivation, seedling morphological characteristics were investigated according to the seedling age of three varieties for 2020 and 2021. The hypocotyl length was less than 2 cm in both years and the 40-day-old seedling was the shortest among all seedling ages. The number and size of leaf were increased with longer seedling age in both years. To evaluate seedling quality, total seedling length, seedling weight, and impact resistance were measured before transplanting. Total seedling length was the longest in 40-day-old seedlings and the shortest in 25-day-old seedlings in both years. In the case of seedling weight, no significant differences were observed depending on the seedling age and the impact resistance increased with increasing seedling age. Finally, 'Jungmo7001', 'Naehan', and 'Tamla' showed a high transplanting rate in seedlings grown for more than 30 days, 35 days, and 40 days, respectively, in the field using a general transplanter. These results suggest that the proper seedling age for transplanting is limited depending on the rapeseed varieties. The suitable seedling cultivation method can be selected for different cultivation environments.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.3
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• pp.210-219
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• 2021

In recent years, air temperature has been increasing rapidly compared to the 1980s because of global warming. This increase in temperature reduces the yield and quality of rice; therefore, measures are needed to prevent such effects and ensure food security. The early maturing type (EMT) of rice is mainly cultivated in the central northern mid-mountainous area (CNMA). This study was conducted to shift the transplanting date of EMT and to examine the adaptability of the mid-maturing type (MMT) or mid-late maturing type (MLMT) in the Jecheon region of the CNMA to address global warming. The air temperature increased by 0.7-0.9℃ in the 2010s, compared to that in the 1980s, and was similar to other decades during the ripening period. Over the past 35 years, considering rice quality, the heading date of the Odae variety has arrived sooner by approximately 10 days, the ripened grain ratio has increased by more than 10%, and the thousand grain weight; however, the mean temperature at 40 days after heading has increased by more than 2℃. The late marginal heading date in the Jecheon region was determined as August 11 based on the accumulated temperature of 880℃ and August 15 based on 840℃ for 40 days after heading. According to different transplanting dates, milled rice yield per 10 a was the highest at 567 kg with June 10 in EMT, 595 kg with June 10 in MMT, and 572 kg with May 30 in MLMT. Considering the late marginal heading date, rice yield, and quality, the optimum transplanting date was June 15 in EMT, June 5 in MMT, and May 30 in MLMT in the Jecheon region of CNMA. Owing to global warming, MMT and MLMT are expected to be reliably cultivated in the CNMA.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.4
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• pp.1-24
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• 2021

The Korean government is currently expanding the business startup incubator support program and funds for new ventures with innovative technology in order to spread the second venture boom. However, despite the fact that entrepreneurial education and mentoring that entrepreneurs should have are important parts for the sustainable growth of the startup, some companies selected for government support programs are reluctant to participate in programs such as entrepreneurship education and mentoring for the sole purpose of funding commercialization. This research addressed the effects of entrepreneurial alertness with opportunity awareness as its medium and the small business mentoring service along with the number of times the mentoring has taken place, on the corporate performances. The results of empirical research are as follow: the first one is that scanning-search and evaluation-judgment can influence a company's performance (financial, non-financial) through opportunity recognition, with the exception of association-connection, which is a sub-factor of entrepreneurial alertness. Secondly, it was found to affect a company's financial and non-financial performance through opportunity recognition for financing mentoring, technical support mentoring, and management support mentoring. Thirdly, it was found that the number of mentoring also affects the financial and non-financial performance of a company through opportunity recognition. The implications of this study are that it should be revisited that program managers consider rooms that do not violate the startup founder's strategic decision-making opportunities when designing and operating the program as entrepreneurial alertness sub-factor association-connection does not affect corporate performance through opportunity recognition. This study also emphasizes the need for customized mentoring to meet the outcome goals of each startup, as it has been empirically clarified that the mentoring provided to the startup by the government's support is important. The contribution of this research is that entrepreneurial alertness and opportunity recognition that are treated as important components in research for entrepreneurship, and the factors of mentoring and mentoring frequency that are recognized as important elements in the practical aspect of startup business are clarified theoretically and empirically as an influential factor in corporate performance. And this study also provide a rationale for the startup business support agency supplying mentoring.

• Journal of Wetlands Research
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• v.23 no.4
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• pp.317-326
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• 2021

The present study was carried out with a view to understand the distribution and ecology of Clihton retropictus (Martens, 1879), a class II endangered wildlife designated and protected by the Ministry of Environment, Republic of Korea, and to suggest the effective conservation and management measures for this species and its habit. First, the distribution of Clihton retropictus was investigated nationwide, and environmental factors such as salinity and substratum were analyzed in consideration of the ecological characteristics of this species. In addition, the individual size, density, and movement of Clihton retropictus per each district surveyed were analyzed. Due to its nature of inhabiting in the brackish water zone, the analysis showed that the salinity of this species was 0.7 ~ 16.6‰ at low tide and 1.0 ~ 17.3% at high tide. It was learned from the analysis of substratum that its composition in each river under investigation was slightly different, but most of substratum had a higher composition ratio than gravel (pebble, 16 ~ 64 mm). On the other hand, the size of each individual was checked by measuring the length of its diameter, and there was almost no change in the individual when the inhabited range of Clihton retropictus was short. However, there was tendency that the longer the habitat range, the bigger the individual size. From surveying the population density by season, it was made clear that, during the summer (July to August) and fall (September to October), the density was relatively higher while the number of individuals decreased significantly during winter (November to December) when the water temperature was lowered. In an effort to effectively establish conservation and management measures, the moving distance was measured, and it became known that, during the surveys in summer and fall when the individuals were active, the individuals moved in more distances than during the winter survey. The results of this study are expected to be utilized as basic data for establishing effective management plans such as creation of habitats for Clihton retropictus, its migration projects and selection of migration destinations which get unavoidable due to development projects.

• Journal of Korea Water Resources Association
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• v.54 no.12
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• pp.1243-1254
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• 2021

For water resources operation or agricultural water management, it is important to accurately predict evapotranspiration for a long-term future over a seasonal or monthly basis. In this study, reference evapotranspiration forecast (up to 12 months in advance) was performed using statistically predicted monthly temperatures and temperature-based Hamon method for the Han River basin. First, the daily maximum and minimum temperature data for 15 meterological stations in the basin were derived by spatial-temporal downscaling the monthly temperature forecasts. The results of goodness-of-fit test for the downscaled temperature data at each site showed that the percent bias (PBIAS) ranged from 1.3 to 6.9%, the ratio of the root mean square error to the standard deviation of the observations (RSR) ranged from 0.22 to 0.27, the Nash-Sutcliffe efficiency (NSE) ranged from 0.93 to 0.95, and the Pearson correlation coefficient (r) ranged from 0.97 to 0.98 for the monthly average daily maximum temperature. And for the monthly average daily minimum temperature, PBIAS was 7.8 to 44.7%, RSR was 0.21 to 0.25, NSE was 0.94 to 0.96, and r was 0.98 to 0.99. The difference by site was not large, and the downscaled results were similar to the observations. In the results of comparing the forecasted reference evapotranspiration calculated using the downscaled data with the observed values for the entire region, PBIAS was 2.2 to 5.4%, RSR was 0.21 to 0.28, NSE was 0.92 to 0.96, and r was 0.96 to 0.98, indicating a very high fit. Due to the characteristics of the statistical models and uncertainty in the downscaling process, the predicted reference evapotranspiration may slightly deviate from the observed value in some periods when temperatures completely different from the past are observed. However, considering that it is a forecast result for the future period, it will be sufficiently useful as information for the evaluation or operation of water resources in the future.