• 한국연소학회:학술대회논문집
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• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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• pp.93-96
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• 2015

Commercial coal gasifiers typically use entrained flow type reactors, but have unique features in terms of reactor shape, gasifying agent, coal feeding type, ash/slag discharge, and reaction stages. The MHI gasifier is characterized as air-blow dry-feed entrained reactor, which incorporates a short combustion stage at the bottom and a tall gasification stage above. This study investigates the flow and reaction characteristics inside a MHI gasifier by using computational fluid dynamics (CFD) in order to understand its design and operation features. For its pilot-scale system at 200 ton/day capacity, the distribution of coal and air supply between the two reaction stages was varied. It was found that the syngas composition and carbon conversion rate were not significantly influenced by the changes in the distribution of coal and air supply. However, the temperature, velocity and flow pattern changed sensitively to the changes in the distribution of coal and air supply. The results suggest that one key factor to determine the operational ranges of coal and air supply would be the temperature and flow pattern along the narrower wall between the two reaction stages.

• 유통과학연구
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• 제19권11호
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• pp.27-36
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• 2021

Purpose: COVID-19, government regulation and social media have changed many aspects of life including consumption behavior. The influence of social media by spreading massive news about COVID-19 also have the impact toward emotions threat, perceived risk, and perceived value of consumption behavior in Bengkulu Province, Indonesia. This research aims to analyze the extent to which changes in the consumption behavior, mainly for purchasing of corona prevention products through indirect distribution channels. Research design, data and methodology: This research was descriptive quantitative using the IPA method with sample of people in Bengkulu Province. This study obtained 208 respondent data from questionnaires and tested the validity and reliability with corrected-item total correlation method. Results: The study found that COVID-19 pandemic and government regulation variable were in quadrant II, in quadrant III there were social media variable, emotions threat and perceived risk. Meanwhile, in quadrant IV there were perceived value variable. Conclusions: The findings indicated that COVID-19 and government regulation are the most variable that influence people to buy corona prevention product, meanwhile perceived value is the less influence variable. Therefore, government and marketers have to prepare strategic plan in order to raise people awareness to avoid corona by buying corona prevention product.

• 생태와환경
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• 제54권1호
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• pp.71-77
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• 2021

Using data from flies collected with pitfall traps in 365 forests on a nationwide scale in Korea, the abundance and distribution changes of two families (Phoridae and Lauxaniidae) in Korean forests were predicted at the genus level according to two climate change scenarios: RCP 4.5 and RCP 8.5. The most suitable temperature for the 17 major genera was estimated using a weighted average regression model. Stichillus and Anevrina displayed the lowest optimum temperature with 7.6℃ and 8.5℃ in annual mean temperature, respectively, whereas Chonocephalus had the highest optimum temperature with 12.1℃. Among thirty genera, seven genera (four from Phoridae and three from Lauxaniidae), which showed their abundance in a bell-type or linear pattern along the temperature gradient, were used for predicting the distribution changes according to the future climate change scenarios. All the taxa of this study are expected to decrease in abundance and distribution as a function of temperature increase. Moreover, cold-adapted taxa were found to be more affected than warm-adapted taxa.

• International Journal of Advanced Culture Technology
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• 제10권4호
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• pp.255-260
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• 2022

It is true that traditional markets have become a great foundation for changes in today's production and distribution. However, with the development of science and information communication gradually, the perspective of distribution has been newly developed. In particular, the digital economy system and the pursuit of perfect competition in the global era have placed a great burden on the traditional market. Accordingly, the government has made numerous efforts to revitalize traditional markets, which has led to the present day. However, the change in production, distribution, and transactional perspectives of newly introduced e-commerce in the position of not being able to deviate from the characteristics of the traditional market, that is, the traditional market, poses another major crisis. Therefore, while maintaining the tradition of the traditional market, the introduction of a new method of electronic trading has a good advantage to become an advanced market, but it has not pursued major changes due to fundamental management methods and small-scale operation. Therefore, I believe that it is urgent to introduce and apply new e-commerce to secure transitional competitiveness in order for the traditional market to be reborn and to pursue change and development into a new advanced market.

• 동아시아경상학회지
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• 제9권4호
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• pp.69-80
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• 2021

Purpose - This study investigated the development process of the Chinese distribution industry and analyzed the current status of China's offline and online distribution industries under the development process of the Chinese distribution industry. In addition, the current status of offline distributors in China and representative companies were analyzed as case studies. Research design, data, and methodology - This study analyzed the overall environment of the Chinese distribution industry by using literature data. Then, this study conducted a case analysis using RT Mart and Jingdong, major companies in the distribution industry. Result -The main research results of this study show that the Chinese distribution market has already matured, and retailers are fiercely competing to secure sales and operating profits through various methods such as finding new management methods, improving awareness and customer loyalty by expanding the number of stores. Conclusion -Recently, the characteristic of China's distribution industry is that the boundaries of distribution are breaking down. Chinese retailers are taking strategies to expand the scope of services by erasing the boundaries of distribution. In other words, distribution companies are promoting a borderless distribution strategy in which consumers purchase products online and offline without restrictions on time and space. In addition, small stores in residential areas are on the rise compared to large-scale stores in the city center. The existing distribution industry operates various types of distribution stores to prepare for the post-COVID-19 crisis.

• 전기학회논문지
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• 제58권7호
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• pp.1281-1286
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• 2009

As a general radial configuration of power distribution system, the various researches have being studied to change a radial configuration to network one such as smart, intelligent and micro grid for loop operation. If a radial configuration changes to network, protective coordination comes to the biggest problem. When a typical protective algorithm is applied to loop distribution system protection, the interrupted section is expanded, therefore, reliability grows worse. This paper presents the new protective method being able to apply to loop distribution system with Distribution Automation System (DAS) which separate the minimal faulted section. Through contingency analysis of the sustained and momentary fault, we analyzed the influence for radial configuration and loop configuration using interrupted area and proved the effectiveness of proposed method.

• 전기학회논문지
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• 제58권7호
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• pp.1270-1275
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• 2009

The structure of a power distribution system will change in a loop configuration such as in the case of a smart grid. If power distribution system changes radial to loop form, the structure may have to be changed significantly. Therefore, we analyzed the reliability indices and calculated a CIC(Customer Interruption Cost) for the loop power distribution system. The power distribution system reliability depends on the protection scheme. This study is applied to the current protection scheme method and is compared with each model. When the CIC was evaluated, most studies performed calculations only for sustained interruptions. However, in actuality, momentary interruption frequencies occurred more than sustain interruptions. Thus, it is occurred the CIC additively. Therefore, we evaluated a CIC including momentary interruption, for each model, and then compared with MAIFI(Momentary Average Interruption Frequency Index)

• 상하수도학회지
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• 제13권2호
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• pp.23-33
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• 1999

This study is to investigate the effect of C factor errors on the analysis of water distribution systems. For this purpose, an artificial distribution network and a real distribution network were selected as the study networks. Results are as follows. 1. The C factor of a pipe which has small velocity didn't give significant effect on the analysis of a water distribution system. 2. The effect of decreased value of C factors give more influence on the analysis of water distribution systems than that of the increased values. 3. For the C factor calibration, errors of the residual water heads as well as those of the head losses should be considered together. 4. In the analysis of water distribution systems, changes of C factors can give influences only on the nodes which locate behind the pipe. Therefore, this characteristics should be considered in the selection of nodes for the measurement of water heads.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.525-526
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• 2007

Recently, there has been growing interest in utilizing distributed generation (DG). However, an insertion of DG to existing distribution system can cause several problems such as voltage variations, harmonics, protective coordination, increasing fault current etc,. The typical protection system of the existing distribution system is designed for radial network. But penetration of DG to distribution system changes existing unidirectional power flow to bidirectional power flow. Therefore, investigation to cover whole field of distribution system must be accomplished such as changing of protection devices rating by increasing fault current, reevaluation of protective coordination. This paper presents that PSCAD/EMTDC simulations was accomplished to analyze effect of DG on the distribution protective coordination. In addition, directional recloser-sectionalizer coordination are evaluates distribution system with DG by using PSCAD/EMTDC simulation.

• 한국전기전자재료학회논문지
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• 제32권2호
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• pp.151-156
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• 2019

The aim of this investigation is to detect specific waveforms in a distribution line prior to the occurrence of a fault. Conditions were introduced such that a feeder remote terminal unit (FRTU) of the distribution automation system selects and stores fault waveforms from the different waveforms detected in the distribution line. In addition, an algorithm was developed to detect specific waveforms from the fault waveforms stored using the FRTU. This algorithm exploits the duration and periodicity of harmonic changes in voltage and current. The efficacy of the algorithm was confirmed based on the measurements of fault waveforms in an actual distribution line. The results indicated that faults in a distribution line can be predicted via experimental measurements.