• 품질경영학회지
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• 제41권1호
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• pp.1-14
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• 2013

Purpose: The purpose of this research was to investigate the spread pattern of Korean legal certification systems and their impact on industry performance. Methods: It first analyzes the life cycle of legal certification systems and classifies them into four categories based on the spread patterns in a chronological view. A survey study is then conducted to find out the impact of legal certification systems on financial performance. Both the legal mandatory certification systems and the legal voluntary certification systems are included in the survey. Results: Four spread patterns of legal certification systems are sustainable growth, stagnation after growth, decrease after growth, and repetition of growth and declination. 56% of 293 certified corporations responded positively about the financial impact of their certification systems. Conclusion: The policy makers can utilize the results of this study in designing additional certification systems as well as promoting the current legal certification systems.

• Genomics & Informatics
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• 제20권2호
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• pp.22.1-22.9
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• 2022

The rise of newer coronavirus disease 2019 (COVID-19) variants has brought a challenge to ending the spread of COVID-19. The variants have a different fatality, morbidity, and transmission rates and affect vaccine efficacy differently. Therefore, the impact of each new variant on the spread of COVID-19 is of interest to governments and scientists. Here, we proposed mathematical SEIQRDVP and SEIQRDV3P models to predict the impact of the Omicron variant on the spread of the COVID-19 situation in South Korea. SEIQEDVP considers one vaccine level at a time while SEIQRDV3P considers three vaccination levels (only one dose received, full doses received, and full doses + booster shots received) simultaneously. The omicron variant's effect was contemplated as a weighted sum of the delta and omicron variants' transmission rate and tuned using a hyperparameter k. Our models' performances were compared with common models like SEIR, SEIQR, and SEIQRDVUP using the root mean square error (RMSE). SEIQRDV3P performed better than the SEIQRDVP model. Without consideration of the variant effect, we don't see a rapid rise in COVID-19 cases and high RMSE values. But, with consideration of the omicron variant, we predicted a continuous rapid rise in COVID-19 cases until maybe herd immunity is developed in the population. Also, the RMSE value for the SEIQRDV3P model decreased by 27.4%. Therefore, modeling the impact of any new risen variant is crucial in determining the trajectory of the spread of COVID-19 and determining policies to be implemented.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2067-2072
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• 2007

Understanding of the impinging behavior of an electrically charged spray is essential in determining appropriate operating conditions for electro-spraying of paints, surface coating materials and insecticides. In the present work, as an initial step, the wall impact of an electrically charged droplet has been experimentally investigated. The charged drops were directed on the surface of a paraffin wax, and the impinging behavior was visualized and recorded using a CCD camera to identify the impingement regime. The spread-rebound boundary for the charged drop turned out to be smaller compared to that for an electrically neutral droplet under the same surface condition. The shift of the transition criterion is considered to be due to the discrepancy between the maximum spread ratio of the electrically charged droplet and that of the neutral droplet.

• 대한기계학회논문집B
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• 제28권9호
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• pp.1093-1100
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• 2004

Numerical analysis of the heat transfer associated with droplet impact on a hot solid surface is performed by solving the equations governing conservation of mass, momentum and energy in the liquid and gas phases. The deformed droplet shape is tracked by a level set method which is modified to achieve volume conservation and to include the effect of contact angle at the wall. The numerical method is validated through the calculations for the cases reported in the literature. Based on the numerical results, the heat transfer rate is found to depend strongly on the droplet spread radius. Decreased advancing/receding contact angles enlarge the splat radius and in turn enhance the wall heat flux. The effect of impact velocity on the droplet spread is reduced as the droplet size decreases. Also, droplet atomization is observed to significantly enhance the heat transfer rate and the effect is pronounced for a smaller size of droplet. An existing model equation to predict the maximum spread radius is improved for application to a micro droplet.

• 아태비즈니스연구
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• 제14권3호
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• pp.221-240
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• 2023

Purpose - This paper investigates how business cycle impacts on corporate credit spreads since global financial crisis. Furthermore, it tests how the impact changes by the phase of the cycle. Design/methodology/approach - This study collected dataset from Barclays Global Aggregate Bond Index through the Bloomberg. It conducted multi-regression analysis by projecting business cycle using Hodrick-Prescott filtering and various cyclical variables, while ran dynamic analysis of 5-variable Vector Error Correction Model to confirm the robustness of the test. Findings - First, it proves to be statistically significant that corporate credit spreads have moved countercyclicaly since the crisis. Second, It indicates that the corporate credit spread's countercyclicality to the macroeconomic changes works symmetrically by the phase of the cycle. Third, the VECM supports that business cycle's impact on the spreads maintains more sustainably than other explanatory variable does in the model. Research implications or Originality - It becomes more appealing to accurately measure the real economic impact on corporate credit spreads as the interaction between credit and business cycle deepens. The economic impact on the spreads works symmetrically by boom and bust, which implies that the market stress could impact as another negative driver during the bust. Finally, the business cycle's sustainable impact on the spreads supports the fact that the economic recovery is the key driver for the resilience of credit cycle.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2995-3000
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• 2008

Understanding of the impinging behavior of an electrically charged spray is essential in determining appropriate operating conditions for electro-spraying of paints, surface coating materials and insecticides. In the present work, the wall impact behavior of an electrically charged drop has been investigated and compared with that of a neutral drop experimentally. The critical Sommerfeld number representing the spread-splash boundary for the charged drop impacting on the dielectric substrate turned out to be larger compared to that for the neutral drop with the same surface condition. The change of the transition boundary is due to the increase in the surface wettability of the drop on the substrate. However, with the electrically conducting substrates, the charging effect on the transition boundary appeared negligible. This is because the electric discharging time is much shorter than the time required for the flattened drop to reach its maximum extent.

• 한국IT서비스학회지
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• 제14권1호
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• pp.263-276
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• 2015

As a social being, people can cooperate and control one another through the power of reputation, which is a critical opinion of someone given by others. Nevertheless, there have been obstacles in clarifying the identity of traditional types of reputation, for they are mostly words of mouth passed among members of a society. However, due to dramatic technological advancement and widespread use of the Internet and social media, now we can clearly see and analyze written reputations, which used to be passed only from mouth to mouth. Against this background, this study examines whether a negativity bias-a notion that an event of a more negative nature has a greater effect on one's psychological state than a positive event-applies to spread of reputation online, and examines related factors and effects. To this end, reputation-related online comments left by social media users during the election period of Korea's 6th provincial election on 4 June 2014 were analyzed. For the analysis, a Bass diffusion model was used, which is based on the innovation diffusion theory. The analysis results confirmed that, at online forum, negative reputations spread more quickly and more widely than positive ones, had a greater impact, and mass media such as online news outlets had a significant influence on spread of reputation online.

• The Journal of Asian Finance, Economics and Business
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• 제7권11호
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• pp.45-53
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• 2020

Past literatures have not studied the impact of real-world events or information on the return and volatility of virtual currencies, particularly on the COVID-19 event, day-of-the-week effect, daily high-low price spreads and information flow rate. The study uses the ARMA-GARCH model to capture Bitcoin's return and conditional volatility, and explores the impact of information flow rate on conditional volatility in the Bitcoin market based on the Mixture Distribution Hypothesis (Clark, 1973). There were 3,064 samples collected during the period from 1^st of January 2012 to 20^th April, 2020. Empirical results show that in the Bitcoin market, a daily high-low price spread has a significant inverse relationship for daily return, and information flow rate has a significant positive relationship for condition volatility. The study supports a significant negative relationship between information asymmetry and daily return, and there is a significant positive relationship between daily trading volume and condition volatility. When Bitcoin trades on Saturday & Sunday, there is a significant reverse relationship for conditional volatility and there exists a day-of-the-week volatility effect. Under the impact of COVID-19 event, Bitcoin's condition volatility has increased significantly, indicating the risk of price changes. Finally, the Bitcoin's return has no impact on COVID-19 events and holidays (Saturday & Sunday).

• 한국항만경제학회지
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• 제38권4호
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• pp.187-198
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• 2022

본 연구는 코로나 19 팬데믹의 전세계적인 확산으로 인하여 국경봉쇄와 이동제한과 같은 방역 조치와 전염병의 확산이 상품무역량을 감소시키는 원인인지를 살펴보고자 하였다. 이를 위해 한국과 주요무역 상대국의 상품무역 통계를 이용하여 중력모형 분석을 실시하였다. 분석 결과 코로나 19 확산시기인 2020년의 경우 코로나 팬데믹의 영향이 한국의 무역을 감소시키는 장애요인이라는 것을 실증적으로 확인 할 수 있었다. 그러나 2021년의 경우 팬데믹의 영향이 상품무역에 유의미한 영향을 주는 지 확인할 수 없었다. 2020년과 2021년의 코로나 19 팬데믹이 미치는 영향이 상이한 만큼 코로나 19 전염병이 안정적으로 관리되고 있는 2022년의 상품무역 상황 역시 달라질 가능성이 존재한다. 코로나에 대한 대응이나 백신의 보급 같은 요인들이 각 국가마다 상이하기 때문에 코로나 시대를 마감하는 정책 수립과정에 있어서 그러한 다양한 요인들을 충분히 고려해야 할 것으로 생각된다

• 한국분무공학회지
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• 제12권4호
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• pp.198-203
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• 2007

In the present work, surface wetting effect on spread-splash regime and transition criterion of the water and ethanol droplets impacting an unheated dry wall has been experimentally investigated. The droplet was directed on a polished STS plate and a glass slide, and the impinging behavior was visualized and recorded using a CCD camera. Droplet diameter and velocity approaching the wall were measured as well. The critical Sommerfeld number representing the spread-splash boundary for the ethanol droplet impinging on the substrates turned out to be smaller compared to that for the water droplet impinging on the substrates with the surface roughness condition remained unchanged. The shift of the transition boundary is considered to be due to the effect of the surface wettability represented by static contact angle and surface tension of droplet.