• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.319-331
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• 2004

This study was conducted to evaluate the ecological impact of freshwater bivalve (Corbiculidae) on plankton communities in experimental enclosure systems (2 m ${\times}$ 2 m ${\times}$ 2 m). During the acclamation period of one month, cyanobacteria, including Microcystis viridis and Microcystis aeruginosa, dominated in both control and treatment enclosures with no noticeable density difference. After the addition of 100 mussels, dominant species of phytoplankton shifted from Microcystis to Scenedesmus in concert with slight decrease in the cell density and the increase of N/P ratio. However, cell density in the control quickly increased, accompanied with changes of dominant species to Oscillatoria spp. With the introduction of additional 500 musseles in the treatment enclosure, dominant phytoplankton species in both enclosures were replaced with Selenastrum spp. and Cryptomonas sp. In the initial stage, the total zooplankton abundance in the control was higher than that of treatment, but it was reversed after the addition 100 mussels. After mussel density increased up to 600 indivisuals, zooplankton density in the treatment decreased with dominance of small taxa, such as rotifers and nauplius. However, abundance and carbon biomass of large zooplankton, such as Bosmina longirostris and Diacyclops thomasi were maintained in a high level compared with those of control. During the study period, Chl. a concentration in mussel treatment and control increased with DIP and $NH_3-N$, respectively. Due to the increase of $NH_3-N$, especially after the introduction of additional 500 mussels, nitrogen limitation did not occur in the treatment enclosure in contrast with strong nutrient limitation occurred in the control. These results indicate that filter-feeding Corbicula could exert important impact on nutrient recycling and plankton community structure in a freshwater ecosystem, through direct feeding and competition for the same food resource as zooplankton on one hand, and through alteration of nutrient availability on the other.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.354-374
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• 2016

This study explored spatiotemporal variability of water quality in correspondence with hydrometeorological factors in the five stations of Paldang Reservoir located in the Han River during 4 years from May 2012 to December 2015. Variability of basic water quality factors were largely related with seasonal fluctuations of hydrology. Temperature stratification occurred in the deep dam station, and prolonged hypoxia was observed during the draught year. Nitrogen nutrients were increased with decreasing inflow in which changing pattern of $NH_4$ reversed to $NO_3$ by the effect of treated wastewater effluent. Phosphorus increase was manifest during the period of high inflow or severe drought. Chl-a variation was reversely related with both flow change and AGP(algal growth potential) variations. Our study demonstrated that water quality variability in Paldang Reservoir was largely attributed to both natural and operational changes of inflow and outflow (including water intake) based on major pollution source of the treated wastewater (total amount of $472{\times}10^3m^3d^{-1}$) entering to the water system from watershed. In the process of water quality variability, meteorological (e.g., flood, typhoon, abnormal rainfall, scorching heat of summer) and hydrological factors (inflow and discharge) were likely to work dynamically with nutrients pulse, dilution, absorption, concentration and sedimentation. We underline comprehensive limnological study related to hydro-meteorolology to understand short- and long-term water quality variability in river-type large reservoir and suggest the necessity of P-free wastewater treatment for the effective measure of reducing pollution level of Paldang drinking water resource.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.2
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• pp.92-100
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• 2005

This study was conducted to find suitable methods for screening organic resources useful for compost. Twenty-seven industrial and domestic sludges were collected from various cities and industrial areas. Contents of organic matters in the sludges were in the range of 79.3-98.0%, and the contents were much higher than the regulation level (60%) for raw materials of compost. Contents of total nitrogen were in the range of 0.8-2.6%. Contents of Fe and Al were very high. Content of HEM was highest in textile sludge ($257mg\;kg^{-1}$) and the contents in the others were in the range of $12.6-90.3mg\;kg^{-1}$. Content of PAHs was lowest in food sludge ($739.1{\mu}g\;kg^{-1}$ and pulp-mill sludge had the highest PAHs content ($3461.8{\mu}g\;kg^{-1}$). $Microtox^{(R)}$ $EC_{50}$ values were higher in the sludges which were classified as a possible material in composting after analysis and investigation. Lettuce root elongation and $EC_{50}$ values were relatively lower in pulp-mill sludge, sewage sludge 3 (Large city), food sludge and leather sludge. Therefore, mineral nutrients, heavy metals, organic compounds (HEM, PAHs, PCBs), and bioassay ($Microtox^{(R)}$ $EC_{50}$, Relative root elongation test) are recommended to be included in the screening system of raw material of compost in addition to the current regulation with organic matter and 8 heavy metals.

• Journal of Climate Change Research
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• v.3 no.1
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• pp.71-88
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• 2012

The global warming is probably the most significant issue of concern all over the world and according to the report published by the Intergovernmental Panel on Climate Change (IPCC), the average temperature and extent of global warming around the globe have been on the rise and so have the uncertainty for the future. Such effects of global warming have adverse effects on basic foundation of the mankind in numerous ways and water resource is no exception. The researches on water resources assessment for climate change are significant enough to be used as the preliminary data for researches in other fields. In this research, a total of 124 peer-reviewed publications and 57 reports on the subject of research on climate change related to water resources, that has been carried out so far in Korea has been reviewed. The research on climate change in Korea (inclusive of the peer-reviewed articles and reports) has mainly focused on the future projection and assessment. In the fields of hydrometeorology tendency and projection, the analysis has been carried out with focus on surface water, flood, etc. for hydrological variables and precipitation, temperature, etc. for meteorological variables. This can be attributed to the large, seasonal deviation in the amount of rainfall and the difficulty of water resources management, which is why, the analysis and research have been carried out with focus on those variables such as precipitation, temperature, surface water, flood, etc. which are directly related to water resources. The future projection of water resources in Korea may differ from region to region; however, variables such as precipitation, temperature, surface water, etc. have shown a tendency for increase; especially, it has been shown that whereas the number of casualties due to flood or drought decreases, property damage has been shown to increase. Despite the fact that the intensity of rainfall, temperature, and discharge amount are anticipated to rise, appropriate measures to address such vulnerabilities in water resources or management of drainage area of future water resources have not been implemented as yet. Moreover, it has been found that the research results on climate change that have been carried out by different bodies in Korea diverge significantly, which goes to show that many inherent uncertainties exist in the various stage of researches. Regarding the strategy in response to climate change, the voluntary response by an individual or a corporate entity has been found to be inadequate owing to the low level of awareness by the citizens and the weak social infrastructure for responding to climate change. Further, legal or systematic measures such as the governmental campaign on the awareness of climate change or the policy to offer incentives for voluntary reduction of greenhouse gas emissions have been found to be insufficient. Lastly, there has been no case of any research whatsoever on the anticipated effects on the economy brought about by climate change, however, there are a few cases of on-going researches. In order to establish the strategy to prepare for and respond to the anticipated lack of water resources resulting from climate change, there is no doubt that a standardized analysis on the effects on the economy should be carried out first and foremost.

• ANNALS OF ANIMAL RESOURCE SCIENCES
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• v.28 no.3
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• pp.97-107
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• 2017

The present study was conducted to investigate the effects on growth performance, nutrient digestibility, and gut health of broiler chickens when a dietary supplementation of multienzymes was added to diets, containing different energy levels. A total of 480 broiler chickens of similar body weight (Ross 308, 1-day-old) were randomly subjected to four treatments. The dietary treatments included a corn-soybean meal-based diet supplemented with: multienzyme (amylase+protease+ mannanase+xylanase+phytase), 0.05% enzyme, and different energy levels (3010 and 3060 kcal/kg). The experimental diets were fed to the chicks in a mash form for 35 days in two phases (1-21 d, phase I; and 22-35 d, phase II). During the overall period, chicks fed with diets supplemented with multienzymes had a better weight gain (p<0.05) and feed conversion ratio (FCR) than those fed with diets without enzymes. There was no difference in the growth rate and FCR among the chicks fed with diets supplemented with enzymes, even though the dietary energy levels were different. The apparent fecal and ileal digestibility of dry matter, gross, crude protein, calcium, and phosphorus were significantly enhanced (p<0.05). The population of cecal and ileal Lactobacillus spp. was significantly increased (p<0.05), and Clostridium spp. and coliforms were significantly decreased (p<0.05) in diets supplemented with enzymes. Villus height and villus height to crypt depth ratio in the small intestine was also significantly enhanced (p<0.05) in diets supplemented with enzymes. In conclusion, multienzyme supplementation had positive effects on the weight gain of broilers, FCR, digestibility of nutrients, and on the growth of intestinal microbiota.

• Korean Journal of Heritage: History & Science
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• v.52 no.1
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• pp.64-81
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• 2019

Jeju Island is located at a strategic position, making it an important waypoint on the sea routes of East Asia. As a result, the island suffered many foreign invasions throughout history. Especially, it is widely known that Japanese pirates frequently invaded the island as the island was located on their way as they were sailing to China. Therefore, they built various defensive structures across the island. Fortresses, where a small number of defenders may fend off an enemy, were built in multiple places on the island. This was a strategy for the island to defend itself, as it was almost impossible to get prompt support in an emergency from the mainland due to the long distance. Fortresses, or walled cities, were the center of politics, culture, and economy of many areas. Therefore, they are a valuable resource to study the history and geographical characteristics of a place. For this reason, studies on fortresses started quite early on. However, studies on such relics in Jeju Island began very late. The research on fortresses was launched during the Japanese occupation for most mainland areas. However, studies on the relics on Jeju Island began as late as the 1970s. This was because scholars did not understand the importance of the city walls and fortresses on Jeju Island, and there were no researchers who specialized in city walls or fortresses on the island, as well. As archeological research on Jeju Island began to gain momentum, the studies on city walls and fortresses saw progress; however, these studies are still of an elementary level. In this study, the author summarized the status of studies on the city walls and fortress relics in Jeju Island and their preservation/maintenance status by era. According to the findings of this study, there were two Corean-era city wall/fortress relics and thirteen from the Chosun era., The researcher analyzed and presented the status of studies and the current condition of the relics. The status of attached structures was also documented.Furthermore, a short review of the maintenance work performed so far was provided. Also, the researcher mentioned the problems that accompanied the maintenance process of these relics, along with suggestions for improvement that could be referred to in future restoration/maintenance projects.

• Management & Information Systems Review
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• v.38 no.2
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• pp.183-208
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• 2019

The purpose of this study is to examine the effects of the transformational leadership on helping behaviors and deviant behaviors of organizational members and to verify the control effect of value consistency and to suggest a process for effective business management and human resource management. For this purpose, questionnaires were distributed to employees working in office management, area marketing, and manufacturing industries in Seoul, Gyeonggi and Chungcheong provinces, and the final 334 copies were used for empirical analysis. Data were analyzed using SPSS 18.0, and reliability analysis, factor analysis for validity, correlation analysis, and regression analysis were conducted to verify the research hypothesis. The results of the empirical analysis based on the questionnaire based on the object are as follows. First, charisma of transformational leadership showed negative impact on helping behavior, and intellectual stimulation of transformational leadership and individual care showed positive influence on helping behavior. Second, charisma of transformational leadership showed negative influence on deviant behavior, whereas intellectual stimulation of transformational leadership and sub - constitutional factor of individual care did not show significant influence on deviant behavior. Third, as a result of confirming the moderating role of transformational leadership and helping behavior on the level of value consistency, it showed moderating effects on charisma and individual consideration of transformational leadership. Through this study, we proved the effectiveness of transformative leadership which increases the helping behaviors of the members and reduces the deviant behavior. Based on this, we proposed the necessity of developing managers' transformational leadership improvement program to enhance the sustainability of the organization. And we confirmed the partial influence relationship on the adjustment effect of value consistency. In addition, negative influence of charisma suggests a significant point in the management process design.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.5
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• pp.15-29
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• 2021

This study is based on ERIS model for start-up performance, and aims to derive the main reason for start-up sustainability centered on organizational resilience. To this end, systematic literature examination and modified Delphi method were used to investigate start-up sustainability factors based on ERIS Model focused on organizational resilience. The results showed that ERIS model-based entrepreneurial continuity factors were divided into four categories: entrepreneur, resource, industrial environment, strategy, subdivision 8 and detailed factors 54. In addition, the ERIS model-based continuity factors were structured around organizational resilience, and the continuity factors were structured according to ERIS model under five categories: leadership, culture, people, system and environment. The results of this study are as follows. First of all, the results of existing research and analysis show that the concept of successful start-up and sustainability of start-up are used in various fields. Second, it is confirmed that there are common factors of influence on start-up performance and start-up sustainability based on ERIS model. Third, Delphi method's results showed that the general characteristics of entrepreneurs, such as academic background, education level, gender, age, and business experience did not affect the sustainability of entrepreneurship. This study is significant in that it is based on ERIS model focused on organization resilience, and ERIS-R, which integrates Strategy into System and Organization resilience into R in the field of gradually expanding start-up development and support. It is expected that the results of this study will improve the sustainability of start-up that can predict, prevent, and overcome various crises at any time.

• Korean Journal of Food Science and Technology
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• v.52 no.6
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• pp.610-615
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• 2020

Edible insects might be used as a means to solve food insecurity caused by population growth. Many studies have investigated the biological activity of insects; however, few studies have investigated the nutritional value of insects. Therefore, the aim of this study was to investigate the nutritional value of Allomyrina dichotoma larva protein (ADP) as a source of protein replacement. In vivo studies were conducted to determine the food efficiency ratio (FER), protein efficiency ratio (PER), and true digestibility (TD) of ADP. Experiments were conducted in 3 groups of 8 animals per group using twenty-four 4-week-old SD rats. The experimental groups included the general diet group (Con), in which 20% of the total Kcal in the diet was composed of casein protein, and the ADP group (ADP), in which 20% of the total Kcal was composed of ADP protein, and a non-protein diet group (NP) to measure the protein (metabolic fecal nitrogen) excreted by metabolic processes in the body. As a result of this experiment, we found that the FERs were 0.52 and 0.41 in the casein protein intake (Con) and ADP groups, respectively, thus showing a significantly lower level in the ADP group. The PERs of ADP and Con were 2.39 and 2.63, respectively. The TD of Con and ADP were 91% and 80%, respectively.

• Korean Journal of Food Science and Technology
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• v.53 no.3
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• pp.356-363
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• 2021

This study investigated the quality characteristics of anchovy sauce fermented using Nuruk to maintain a unique flavor, reduce fishy smell, and improve the fermentation rate. Six kinds of fermented fish sauces, including the control, fermentation using traditional Nuruk; SH Koji (Fs-A), JJ Koji (Fs-B), GJ Koji (Fs-C); and fermentation with improved Nuruk; Aspergillus luchuensis (Fs-D) and Aspergillus oryzae (Fs-E), were prepared. Samples were collected at 15 days intervals with 10% Nuruk added to raw anchovy and fermented at 25o C for 60 days. The free amino acids, especially glutamic acid content and amino nitrogen, were the highest in Fs-C, reflecting the high protease activity of Nuruk C (GJ). Regarding overall sensory evaluation, the control was the lowest, whereas Fs-C was highly evaluated among the sample groups. The addition of Nuruk not only shortened the fermentation period, but also increased the overall sensory level by adding umami and reducing fishy odor.