• Korean Journal of Ecology and Environment
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• v.57 no.1
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• pp.39-50
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• 2024

In ecosystems within limited resources, interspecific competition is inevitable, often leading to the competitive exclusion of inferior species. This study aims to provide foundational information for the conservation and restoration management of Microphysogobio rapidus by evaluating species' ecological response to biological factors within its habitat. To understand this relationship, we collected food web organisms from site where M. rapidus coexist with Microphysogobio yaluensis, a specie ecologically similar to M. rapidus, and evaluated the trophic levels (TL), isotopic niche space (INS), and the overlap of INS among fishes within the habitat using stable isotope analysis. Our analysis revealed that the M. rapidus exhibited a higher TL than M. yaluensis, with TL of 2.6 and 2.4, respectively. M. yaluensis exhibited a broad INS, significantly influencing the feeding characteristics of most fish. Conversely, M. rapidus showed a narrow INS and asymmetric feeding relationships with other species, in habitats with high competition levels. This feeding characteristics of M. rapidus indicate that the increase in competitors sharing the similar resources lead to a decrease in available resources and, consequently, is expected to result in a decrease in their density.

• Journal of Venture Innovation
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• v.7 no.1
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• pp.91-110
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• 2024

In this study, we compared and analyzed the influence of self-leadership on innovative behavior and the mediating effect of job satisfaction among R&D practitioners in manufacturing and information communication technology (ICT) industries. To accomplish this, we conducted an online survey using random sampling methods and collected data from 209 respondents. We employed exploratory factor analysis, reliability analysis, correlation analysis, multiple regression analysis, and mediation analysis using SPSS 20.0 software to analyze the data and to compare differences between the manufacturing and ICT sectors. The research findings are as follows: Firstly, both in manufacturing and ICT sectors, self-leadership showed significant positive correlations with job satisfaction and innovative behavior. Secondly, in the analysis of the impact of self-leadership on innovative behavior, in the manufacturing sector, only natural reward strategy and constructive thought strategy showed significant positive effects, while in the ICT sector, behavioral-oriented strategy, natural reward strategy, and constructive thought strategy all showed significant positive effects. Thirdly, in the analysis of the impact of self-leadership on job satisfaction, in the manufacturing sector, only natural reward strategy and constructive thought strategy showed significant positive effects, while in the ICT sector, behavioral-oriented strategy and natural reward strategy showed significant positive effects. Fourthly, in the analysis of the impact of job satisfaction on innovative behavior, significant positive effects were observed in both manufacturing and ICT sectors, with manufacturing sector having relatively greater impact than ICT sector. Lastly, the results of the analysis on the mediating effect of job satisfaction indicate that in the manufacturing sector, only a constructive thinking strategy significantly influences, showing partial mediating effects. However, in the ICT sector, no mediating effects of job satisfaction were observed for any sub-factors of self-leadership. These research findings highlight differences in the mechanisms of action of self-leadership on innovative behavior and its mediating effects between the manufacturing and ICT sectors. Furthermore, the results suggest the importance of improving organizational strategies and culture towards promoting leadership, job design, and job satisfaction, considering the characteristics of each industry and research and development organization.

• Journal of Venture Innovation
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• v.7 no.1
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• pp.131-149
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• 2024

This study was important considering the prevalence of small business owners in the Korean economy and the challenges they faced amidst an economic downturn. The business performance of these owners was crucial for their survival. Thus, an empirical analysis was conducted to identify factors influencing their management performance. The analysis included personal characteristics of small business owners such as innovativeness, management capability, need for achievement, and technical capability as independent variables, along with product differentiation factors. Additionally, the moderating effect of social capital on these variables and their impact on management performance was tested. To achieve this, a survey targeting small business owners across Korea was conducted, and data from 250 respondents were utilized. Hierarchical regression analysis using SPSS 24.0 was employed for the empirical analysis. The results indicated that management capability, need for achievement, and product differentiation significantly positively impacted business performance. However, the impact of innovativeness and technical capability was not tested. The influence of the variables on business performance ranked as follows: product differentiation, management capability, and need for achievement. The moderating effect of social capital was significant in the relationship between management capability, need for achievement, and management performance, enhancing these relationships. However, the moderating effect of social capital on the relationship between innovativeness, technical capability, product differentiation, and management performance was not tested. These findings underscored the importance of management capability, need for achievement, and product differentiation as key factors affecting the management performance of Korean small businesses. This study was significant as it provided insights into improving the management performance of small business owners in challenging economic conditions by highlighting how the influence of these factors varied depending on the social capital possessed by the owners.

• Journal of Venture Innovation
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• v.7 no.1
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• pp.151-166
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• 2024

The global economic growth rate has been slowed due to changes in the economic and social environment related to the recent trends in the construction market and construction industry, prolonged inflation, intense tensions among countries, and increased interest rates. Since the workers in the construction industry, due to the nature of the industry, move to another site after the completion of an awarded project rather than staying for a long time while performing work at one workplace, various issues are brought out such as poor working environment resulting from unfairness in construction contracts, aging of workers, their anxiety, and job instability. The previous studies on the turnover intention of construction industry workers mainly dealt with external aspects such as leadership, job embeddedness, and organizational citizenship behavior, while the psychological impact was overlooked. The purpose of this study was to develop a measure to reduce or alleviate turnover intention of construction industry workers by verifying empirically the relationship among psychological capital, organizational commitment, and turnover intention among them. For the purpose, whether psychological capital influences organizational commitment and turnover intention, the impact of organizational commitment on turnover intention, and whether organizational commitment has a mediating effect in the relationship between psychological capital and turnover intention, among 310 construction industry workers in the metropolitan area. The results are as follows: First, hope and self-efficacy were found to have a negative (-) effect on turnover intention, while resilience and optimism from psychological capital did not have a significant effect. Second, hope, resilience, and optimism from psychological capital were found to have a positive (+) effect on organizational commitment, while self-efficacy from psychological capital had no significant effect. Third, organizational commitment was found to have a significant mediating effect on the relationship between hope from psychological capital and turnover intention. The results of this study showed that, in construction industry workers, psychological capital affects turnover intention through the mediating effect of organizational commitment. While previous studies mainly considered external influences on the turnover intention of construction industry workers, this study has academic implications in that it sought to strengthen organizational commitment and alleviate turnover intention by approaching psychological aspects. As a practical implication, it was found that higher self-efficacy and hope for work in the organization, from psychological capital, in the construction industry workers were found to lower turnover intention through job performance in a psychologically stable state. It is considered, therefore, that various systems, including job autonomy and flexible work, should be established to improve self-efficacy and hope.

• Korean Journal of Ecology and Environment
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• v.57 no.2
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• pp.102-110
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• 2024

This study presents a fine scale distribution of the endangered species, Odontobutis obscura, through field surveys and literature reviews. Using the mark-recapture method, the population size in major habitats was determined. Field surveys conducted on 18 streams in Geoje Island revealed that the O. obscura was only found in the main streams and tributaries of the Sanyang, Gucheon, and Buchun Streams, which are part of the Sanyang Stream watershed. The O. obscura exhibited relative abundances ranging from 0.5% to 35.3% at different locations, with certain spots showing higher relative abundances (18.8% to 35.3%), indicating major habitat areas. A review of six literature studies confirmed the presence of the O. obscura, although there were differences in occurrence status depending on the purpose, scope, and duration of the studies. Combining the results of field and literature surveys, it was found that the O. obscura inhabits the main and tributary streams of the Sanyang, Gucheon, and Buchun Streams, from the upper to lower reaches. Currently, the O. obscura population in the Sanyang Stream watershed maintains a stable habitat, but its limited distribution range suggests potential issues such as genetic diversity deficiency in the long term. The population size of the O. obscura was confirmed at two specific locations, with densities of 0.5 to 1.5 individuals per m². The average movement distance from the release point was 13.1 m, indicating the limited mobility characteristic of ambush predators. Understanding the distribution and population size of endangered species is the first step towards their conservation and protection. Based on this information, further research could significantly contribute to the conservation of the O. obscura.

• Journal of Korea Port Economic Association
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• v.40 no.1
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• pp.151-163
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• 2024

This study sought to confirm the impact of analytical methods and behavioral economic theory factors on decision-making when making chartering decisions in the dry bulk shipping market. This study on chartering decision-making model was began to verify why shipping companies do not make rational decision-making and behavior based on analytical methods such as freight prediction and process of alternative selection in the same market situation. To understand the chartering decision-making model, it is necessary to study the impact of behavioral economic theory such as heuristics, loss aversion, and herding behavior on chartering decision-making. Through AHP analysis, the importance of the method factors relied upon in chartering decision-making. The dependence of the top factors in chartering decision-making was in the following order: market factors, heuristics, internal factors, herding behavior, and loss aversion. Market factors, heuristics, and internal factors. As for detailed factors, spot freight index and empirical intuition were confirmed as the most important factors relied on when making decisions. It was confirmed that empirical intuition is more important than internal analysis, which is an analytical method. This study can be said to be meaningful in that it academically researched and proved the bounded rationality of humans, which cannot be fully rational, and sometimes relies on experience or psychological tendencies, by applying it to the chartering decision-making model in the dry bulk shipping market. It also suggests that in the dry bulk shipping market, which is uncertain and has a high risk of loss due to decision-making, the experience and insight of decision makers have a very important impact on the performance and business profits of the operation part of shipping companies. Even though chartering are a decision-making field that requires judgment and intuition based on heuristics, decision-makers need to be aware of this decision-making model in order to reduce repeated mistakes of deciding contrary to market situation. It also suggests that there is a need to internally research analytical methods and procedures that can complement heuristics such as empirical intuition.

• The Korean Journal of Medicine
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• v.99 no.3
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• pp.149-157
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• 2024

Background/Aims: Carbapenems are recommended for treating bacteremia caused by extended-spectrum β-lactamase (ESBL) producing Enterobacteriaceae (ESBL-E). However, this has resulted in a significant rise in the utilization of carbapenems in cases of ESBL-E infection. We evaluated the clinical outcomes of patients with ESBL-E bacteremia treated with non-carbapenem antimicrobials. Methods: We conducted a retrospective case-control study of a cohort of patients with documented ESBL-E bacteremia from January 2021 to December 2021. The patients were divided into two groups according to whether they received non-carbapenem or carbapenem therapy. The rates of treatment failure, 30-day mortality and microbiologic failure, and the durations of hospitalization and of antimicrobial therapy were compared between the two groups. Antimicrobial susceptibility testing and phenotypic identification of ESBL-E were performed using the Vitek 2 system. Results: Of 118 patients with ESBL-E bacteremia, 54 received non-carbapenem drugs (non-carbapenem group [NCG]) and 64 received carbapenems (carbapenem group [CG]). Treatment failure at 30 days occurred in 16.7% of the patients in the NCG and in 18.8% in the CG (p = 0.65). The 30-day mortality rate was 14.8% in the NCG and 17.2% in the CG (p = 0.63). Extra-urinary tract infection and prior antimicrobial therapy within 30 days were risk factors for treatment failure in patients with ESBL-E bacteremia. The clinical outcomes did not differ significantly between the two groups, challenging the prevailing preference for carbapenems in the treatment of ESBL-E bacteremia. Conclusions: Non-carbapenem antimicrobials such as piperacillin/tazobactam are recommended for patients with mild ESBL-E bacteremia in South Korea.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.24 no.1
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• pp.26-36
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• 2024

Lesch-Nyhan syndrome (LNS) is an Clinical symptoms can range from mild to severe depending on residual enzyme activity and genetic mutations. In Korea, 27 cases of LNS have been reported. We report the results of an 11-year comparative follow-up of two cases of children who visited because of pink diapers, one who died from LNS with no residual enzymes and one case with partial residual enzymes. Case 1: During follow-up, seizures, developmental delay, and regression were observed. The boy experienced insomnia and severe constipation. He exhibited self-mutilating behavior, a grand mal seizure, scoliosis with severe spasticity, truncal hypotonia, choreoathetoid movement, and ataxia. After prolonged emaciation, staghorn calculi, and recurrent pneumonia, the patient died suddenly at the age of 11 years. Genetic testing revealed a hemizygous HPRT1 variant (c.151C>T (p.Arg51Ter)). Uric acid level was 10.5 mg/dL (normal range: ~3.5-7.9) and HPRT activity 0.02 nmol/hr/spot (10-23.8 nmol/hr/spot). Case 2: During follow-up, the patient remained underweight. He has normal intelligence attending primary school. Self-mutilation symptoms were not observed. Regular renal ultrasonography did not reveal urolithiasis. The patient had a hemizygous HPRT1 variant (c.35A>C (p.Asp12Ala)). Uric acid level and HPRT activity were 11 mg/dL and 0.56 nmol/hr/spot. Pink diapers after the neonatal period and severe protein aversion, neurological problems, and kidney stones, differentiation for LNS is necessary. When suspected, serum uric acid levels, HPRT enzyme activity, and molecular biological tests may be helpful in predicting the prognosis of LNS.

• Journal of Bio-Environment Control
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• v.32 no.4
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• pp.342-352
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• 2023

Ultra-violet (UV) light is one of abiotic stress factors and causes oxidative stress in plants, but a suitable level of UV radiation can be used to enhance the phytochemical content of plants. The accumulation of antioxidant phenolic compounds in UV-exposed plants may vary depending on the conditions of plant (species, cultivar, age, etc.) and UV (wavelength, energy, irradiation period, etc.). To date, however, little research has been conducted on how leaf thickness affects the pattern of phytochemical accumulation. In this study, we conducted an experiment to find out how the antioxidant phenolic content of kale (Brassica oleracea var. acephala) leaves with different thicknesses react to UV-A light. Kale seedlings were grown in a controlled growth chamber for four weeks under the following conditions: 20℃ temperature, 60% relative humidity, 12-hour photoperiod, light source (fluorescent lamp), and photosynthetic photon flux density of 121±10 µmol m^-2 s^-1. The kale plants were then transferred to two chambers with different CO₂ concentrations (382±3.2 and 1,027±11.7 µmol mol^-1), and grown for 10 days. After then, each group of kale plants were subjected to UV-A LED (275+285 nm at peak wavelength) light of 25.4 W m^-2 for 5 days. As a result, when kale plants with thickened leaves from treatment with high CO₂ were exposed to UV-A, they had lower UV sensitivity than thinner leaves. The Fv/Fm (maximum quantum yield on photosystem II) in the leaves of kale exposed to UV-A in a low-concentration CO₂ environment decreased abruptly and significantly immediately after UV treatment, but not in kale leaves exposed to UV-A in a high-concentration CO₂ environment. The accumulation pattern of total phenolic content, antioxidant capacity and individual phenolic compounds varied according to leaf thickness. In conclusion, this experiment suggests that the UV intensity should vary based on the leaf thickness (age etc.) during UV treatment for phytochemical enhancement.

• Journal of Bio-Environment Control
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• v.32 no.4
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• pp.366-376
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• 2023

This study was conducted to develop a model for predicting the growth of kimchi cabbage using image data and environmental data. Kimchi cabbages of the 'Cheongmyeong Gaual' variety were planted three times on July 11th, July 19th, and July 27th at a test field located at Pyeongchang-gun, Gangwon-do (37°37' N 128°32' E, 510 elevation), and data on growth, images, and environmental conditions were collected until September 12th. To select key factors for the kimchi cabbage growth prediction model, a correlation analysis was conducted using the collected growth data and meteorological data. The correlation coefficient between fresh weight and growth degree days (GDD) and between fresh weight and integrated solar radiation showed a high correlation coefficient of 0.88. Additionally, fresh weight had significant correlations with height and leaf area of kimchi cabbages, with correlation coefficients of 0.78 and 0.79, respectively. Canopy coverage was selected from the image data and GDD was selected from the environmental data based on references from previous researches. A prediction model for kimchi cabbage of biomass, leaf count, and leaf area was developed by combining GDD, canopy coverage and growth data. Single-factor models, including quadratic, sigmoid, and logistic models, were created and the sigmoid prediction model showed the best explanatory power according to the evaluation results. Developing a multi-factor growth prediction model by combining GDD and canopy coverage resulted in improved determination coefficients of 0.9, 0.95, and 0.89 for biomass, leaf count, and leaf area, respectively, compared to single-factor prediction models. To validate the developed model, validation was conducted and the determination coefficient between measured and predicted fresh weight was 0.91, with an RMSE of 134.2 g, indicating high prediction accuracy. In the past, kimchi cabbage growth prediction was often based on meteorological or image data, which resulted in low predictive accuracy due to the inability to reflect on-site conditions or the heading up of kimchi cabbage. Combining these two prediction methods is expected to enhance the accuracy of crop yield predictions by compensating for the weaknesses of each observation method.