• Transactions of the Korean hydrogen and new energy society
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• v.34 no.5
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• pp.514-525
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• 2023

This study conducted numerical simulations with the purpose of analyzing the impact of variations in outlet pressure conditions under extreme temperature conditions on the fluid dynamics and performance of a check valve utilized in hydrogen refueling systems. Under the extreme temperature conditions, changes in outlet pressure conditions of the check valve were investigated to analyze velocity distributions, pressure distributions, and temperature distributions in the operational and connection regions. The analysis results indicated that changes in outlet pressure had a significant influence on the internal temperature variation of the check valve. Furthermore, due to density variations in the connection region caused by the cooling effect of excessively cooled hydrogen, a bias in the primary flow direction towards the lower part of the valve outlet was observed in the outlet area. Through a comparison of the results of the valve's inherent flow performance, represented by the flow coefficient, it was observed that when the pressure difference between the inlet and outlet was below 0.37 MPa, sufficient flow was not ensured.

• Journal of Acupuncture Research
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• v.40 no.4
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• pp.319-328
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• 2023

Facial nerve palsy refers to sudden, unilateral lower motor neuron facial paralysis. This study aimed to determine the importance of neck treatment in the treatment of facial paralysis. A literature search was performed on six online databases and other sources until January 15, 2023. A total of 426 papers were retrieved. After excluding duplicated and inconsistent papers, papers not including cervical treatment, and experimental papers on animals, two papers were finally selected. The type of treatment method, therapeutic effects, assessment of the risk of bias in randomized controlled trials, and non-randomized controlled trials and side effects were evaluated. Chiropractic, manual therapy, facial meridian massage, and acupotomy were applied to the face and cervical spine region. The results showed that each treatment had a significant therapeutic effect through evaluation index measurement methods, such as the visual analog scale and Yanagihara's unweighted regional grading system. This study demonstrated the importance of the cervical spine area in the treatment of facial paralysis. However, this study has many limitations. Thus, high-quality randomized controlled comparative studies on the treatment of the cervical spine area only or studies that include cervical spine area treatment as an interventional treatment while performing oriental or comprehensive treatment are needed.

• Clinical Nutrition Research
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• v.13 no.2
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• pp.130-138
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• 2024

Numerous studies have indicated that low levels of serum adiponectin are linked with the development of various chronic diseases. While some recent research has suggested that soy has a positive impact on serum adiponectin levels, the results are inconsistent. Therefore, we aim to conduct a thorough systematic review and meta-analysis of randomized controlled trials (RCTs) that investigate the effects of soy on serum adiponectin levels in adults. The search was conducted until March 2024 on PubMed, Scopus, Web of Science, and Cochrane Library databases to identify RCTs that studied the effects of soy supplementation on serum adiponectin levels. A random-effects model was used to pool the weighted mean differences (WMDs). Ten and nine RCTs were selected for the systematic review and meta-analysis, respectively. After analyzing data from 9 eligible RCTs, it was found that soy supplementation did not significantly impact the concentrations of adiponectin (WMD = -0.24㎍/mL; 95% confidence interval, -1.56 to 1.09; p = 0.72). However, there was significant heterogeneity between the studies (I² = 89.8%, p < 0.001). Sensitivity analysis showed that overall estimates were not affected by the elimination of any study. We did not observe any evidence regarding publication bias. In conclusion, soy supplementation did not have a significant effect on adiponectin levels in adults. However, further RCTs are needed with longer intervention duration, higher doses, and studies conducted in different countries.

• Clinical Endoscopy
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• v.55 no.6
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• pp.742-750
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• 2022

Background/Aims: Cold snare polypectomy (CSP) is commonly used for the resection of colorectal polyps ≤10 mm. Data regarding the influence of snare type on CSP effectiveness are conflicting. Hence, this meta-analysis aimed to compare the outcomes and safety of thin- and thick-wire snares for CSP. Methods: A comprehensive search of the literature published between 2000 and 2021 was performed of various databases for comparative studies evaluating the outcomes of thin- versus thick-wire snares for CSP. Results: Five studies with data on 1,425 polyps were included in the analysis. The thick-wire snare was comparable to the thin-wire snare with respect to complete histological resection (risk ratio [RR], 1.03; 95% confidence interval [CI], 0.97-1.09), overall bleeding (RR, 0.98; 95% CI, 0.40-2.40), polyp retrieval (RR, 1.01; 95% CI, 0.97-1.04), and involvement of submucosa in the resection specimen (RR, 1.28; 95% CI, 0.72-2.28). There was no publication bias and a small study effect, and the relative effects remained the same in the sensitivity analysis. Conclusions: CSP using a thin-wire snare has no additional benefit over thick-wire snares in small colorectal polyps. Factors other than snare design may play a role in improving CSP outcomes.

• Journal of Distribution Science
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• v.22 no.9
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• pp.49-63
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• 2024

Purpose: This study examines how psychological heuristics influence stock price dynamics in Korea's distribution industry after significant price shocks. Research Design, Data, and Methodology: The study analyzes daily stock price movements exceeding 10% for Korean distribution companies from 1993 to 2022. It establishes anchoring heuristic reference points, including the 52-week high and low, and segments the sample based on company size and volatility. Results: We analyzed a sample previously studied by Lee et al. (2023). Our findings indicate that when a stock experiences a positive (negative) price shock near its 52-week high (or lowest price), investors in large (small) companies exhibit an optimism (pessimism) bias. This leads to overreactions and subsequent stock price reversals after the event date. Conversely, when a stock encounters a negative (positive) price shock near its 52-week high (or lowest price), investorstend to underreact due to anchoring heuristics. Thisresultsin a drift effect on the stock price after the event day. Notably, investor behavior around 52-week highs or lows directly impacts their heuristic behavior related to those price points. Conclusions: This paper uniquely examines behavioral biases among distribution-related stock investors in Korea, shedding light on stock price reversal and drift effects.

• The Journal of the Korea Contents Association
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• v.22 no.4
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• pp.379-402
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• 2022

The purpose of this study was to verify the effectiveness of the employee metacognition and it's positive effect on employee agility. Also it aims to investigate the mechanism through the cascading multi-mediating effect through the role breadth self-efficacy and learning agility in such a relationship. In order to solve the common-method bias, independent and dependent variables were measured with time lag, and the relationship between variables was clearly verified by applying the position and the length of time worked with the supervisor as control variables. In testing the hypothesis, 478 questionnaires collected from whom worked at the company has more than 300 office workers in various industries were analyzed. As the result, firstly metacognition had a significant positive(+) effect on employee agility. Second, role breadth self-efficacy was found to positively mediate the relationship between metacognition and employee agility. Third, learning agility was found to mediate metacognition and employee agility positively(+). Fourth, metacognition serially mediates role breadth self-efficacy and learning agility, and the positive(+) effect on employee agility was verified. In addition, metacognition had a greater effect on member agility when passing through role breadth self-efficacy and learning agility rather than the direct effect on employee agility.

• Korean Journal of Social Welfare
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• v.64 no.1
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• pp.79-100
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• 2012

The predominant concern of the study consist in: (1) the direct effect of social commitment on teachers' intervention efficacy for helping both victims and offenders in school violence situation; (2) the indirect effects of both teachers' perceptions of offenders and victims, and fairness of school regulations on teachers' intervention efficacy. Research is based on a survey conducted with 351 teachers(84 males and 267 females) from 10 middle schools located in different districts of the city of Daegu. In order for subjects to verify research questions, structural equation models in teachers' intervention efficacy for helping both victims and offenders were explored. In order to verify the difference between mediators' effect, along with total indirect effect and each individual mediator's effects, bias-corrected bootstrapping analysis by using Mplus were employed. The major findings of the study supported the significance on direct effect of social commitment, and indirect effect of both fairness of school regulations and teachers' perceptions toward offenders and victims, on teachers' intervention efficacy. However, the indirect effect of fairness of school regulations(.025) was far outweighed by teachers' perceptions(.224) toward offenders and victims. In conclusion, the above findings claim our attention in that they provide a range of practical implications for teachers and other related professionals including school workers who are engaged in helping out both victims and offenders in school violence situation.

• The Korean Journal of Franchise Management
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• v.13 no.1
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• pp.35-46
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• 2022

Purpose: With the rapid changes in the technical development and the trend of consumption trend, the convenience store industry is facing an unprecedented competitive situation in the consumption environment where the boundary between online and offline is broken due to the stagnation of offline distribution channels and the spread of online shopping. The biggest innovation strategy of the major convenience store brands in recent years are introducing the O2O (Online to Offline) platform and presenting new products and services beyond the boundaries of online and offline to transform themselves into Omni Channel stores. The study is designed to analyze the effect of innovativeness of convenience store as a stimulus in O2O platform which customers perceive on store loyalty, the final response to external stimuli, through customer engagement with convenience store brands. Specifically, the innovativeness of convenience stores was divided into types of core activities in corporate marketing and focused on innovations in services, products(proposals), promotions and experiences. Research design, data, and methodology: Various hypotheses have been developed to achieve this research purpose. The data were collected from 1,128 questionnaires the age between 15 and 60 who had experience using retail store apps and delivery apps and were analyzed using SPSS 22.0 and SmartPLS 3.3.7 program. Measurement model analysis was carried out to assess convergent and discriminant validity. Also, common method bias was tested using the values of VIF (variance inflation factor). The hypotheses were tested using structural equation modeling with SmartPLS 3.3.7 program. Results: First, service innovation has a positive effect on cognitive engagement. Second, product, promotion and experience innovation have a positive effect on cognitive and affective engagement. Third, cognitive influences affective engagement. Finally, both cognitive and affective engagement affect store loyalty, but affective engagement has a stronger effect on store loyalty than cognitive engagement. Conclusions: All four types of innovation and cognitive engagement have a positive effect on emotional engagement, which has a stronger effect on store loyalty than cognitive engagement. Thus, while innovation can build loyalty through emotional engagement, innovation strategies must be designed and pursued with caution in terms of impact through cognitive engagement may not achieve the planned goals.

• The Korean Journal of Health Service Management
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• v.9 no.3
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• pp.175-185
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• 2015

Objectives : This study was did a meta-analysis of emergency room visits decreased effectiveness of self management education interventions in asthma among adult patients with asthma. Methods : A search of the database PubMed resulted in identifying 8,619 studies done between January 1990 and November 2012. STATA version 10.0 was used to analyze the effect size, explore possible causes of heterogeneity, and determine publication bias with a funnel plot. Results : We included 7 cases on emergency room visits decreased effectiveness of self management and education. Asthmatic patients experienced fewer attacks (summary effect size, 0.75; 95% confidence interval [CI], 0.65-0.95). We found that emergency room visits decreased effectiveness of self management and education were associated with statistically significant effects. Conclusions : Based on these finding, self management and education on interventions are necessary to prevent asthmatic attacks in patients and to reduce the severity of the attacks, and self management and education programs are needed in Korea.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.5 s.335
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• pp.1-8
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• 2005

A RC parallel gate model is used to consider gate distributed effect that affects RF MOSFET performance, and extraction formula based on $Y_{11}$-parameters are used to extract model parameters directly from measured S-parameters. Better agreement between measured and modeled S-parameters in the frequency range beyond 10 GHz is achieved by using the RC parallel model than conventional Rg one, demonstrating the accuracy of the RC model and extraction technique. Using these extraction methods, gate voltage dependent curves of RC gate model parameters are newly extracted, and these parameter data will greatly contribute to developing a RF nonlinear gate model.