• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.104-104
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• 2015

Due to the demand of the cold neutron flux in the neutron science and beam utilization technology, the cold neutron source (CNS) has been constructed and operating in the nuclear research reactor all over the world. The majority of the heat load removal scheme in the CNS is two-phase thermosiphon using the liquid hydrogen as a moderator. The CNS moderates thermal neutrons through a cryogenic moderator, liquid hydrogen, into cold neutrons with the generation of the nuclear heat load. The liquid hydrogen in a moderator cell is evaporated for the removal of the generated heat load from the neutron moderation and flows upward into a heat exchanger, where the hydrogen gas is liquefied by the cryogenic helium gas supplied from a helium refrigeration system. The liquefied hydrogen flows down to the moderator cell. To keep the required liquid hydrogen stable in the moderator cell, the CNS consists of an in-pool assembly (IPA) connected with the hydrogen system to handle the required hydrogen gas, the vacuum system to create the thermal insulation, and the helium refrigeration system to provide the cooling capacity. If one of systems is running out of order, the operating research reactor shall be tripped because the integrity of the CNS-IPA is not secured under the full power operation of the reactor. To prevent unscheduled reactor shutdown during a long time because the research reactor has been operating with the multi-purposes, the introduction of the standby cooling system (STS) can be a solution. In this presentation, the design considerations are considered how to design the STS satisfied with the following objectives: (a) to keep the moderator cell less than 350 K during the full power operation of the reactor under loss of the vacuum, loss of the cooling power, loss of common electrical power, or loss of instrument air cases; (b) to circulate smoothly helium gas in the STS circulation loop; (c) to re-start-up the reactor within 1 hour after its trip to avoid the Xenon build-up because more than certain concentration of Xenon makes that the reactor cannot start-up again; (d) to minimize the possibility of the hydrogen-oxygen reaction in the hydrogen boundary.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.394-397
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• 2000

Lab-scale biofilter was evaluated for the removal of styrene from a waste gas stream. Compost and polyurethane form were used as packing material (50 : 50) and activated sludge from a wastewater treatment plant was innoculated initially. Nitrogen limitation was observed during the biofilter operation and nitrogen source should be properly supplemented. When ammonium sulfate is used as N-source. 200mg carbon was removed for each mg of nitrogen. The effects of the volumetric styrene loading on the styrene elimination capacity (EC) and the removal efficiency (RE) was also tested. The results showed $EC_{max}$ was 4.8kg $C/m^3{\cdot}day$ and above RE 95% was achieved at EBRT 1min.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2769-2774
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• 2007

In vacuum ejector-diffuser systems where a finite volume secondary chamber is used, the secondary jet exhibits transient characteristics during start-up. A steady state is achieved after some time in which mass entrainment prevails indefinitely inside the ejector, though there is no flow from the secondary chamber. An attempt is made in this work to study the infinite entrainment of secondary jet into the primary jet from a finite secondary chamber, with the help of a computational fluid dynamics method. The present study is also intended to identify the operating range of vacuum ejector-diffuser systems where the steady flow assumption can be applied without uncertainty. The results obtained show that the only condition in which an infinite mass entrainment is possible is the generation of a re-circulation zone near the primary nozzle exit. The flow in the secondary chamber attains a state of dynamic equilibrium at this point. Steady flow assumption is valid only after this point.

• International Journal of Computer Science & Network Security
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• v.23 no.3
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• pp.81-93
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• 2023

The popularity of short-form video platforms like TikTok has increased recently. Short-form videos are significantly shorter than traditional videos, and viewers regularly switch between different types of content to watch. Therefore, a successful prefetching strategy is essential for this novel type of video. This study provides a resource-effective prefetching technique for streaming short-form videos. The suggested solution dynamically adjusts the quantity of prefetched video data based on user viewing habits and network traffic conditions. The results of the experiments demonstrate that, in comparison to baseline approaches, our method may reduce data waste by 21% to 83%, start-up latency by 50% to 99%, and the total time of Re-buffering by 90% to 99%.

• Korean small business review
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• v.43 no.4
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• pp.59-93
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• 2021

This study surveyed 413 small business owners who experienced closure to see how the loss perception experienced by small business owners affects their comeback through fear of failure. The analysis results are as follows. First, the larger the received loss of financial capital, market capital, and social capital, the greater the fear of failure. Second, the greater the fear of failure, the less willingness to re-start-up, but it did not affect the willingness to work. Third, perceived loss of financial capital, market capital, and social capital grew fear of failure, which negatively affected the willingness to re-start. However, as for the willingness to work, only the perception of loss to market competitiveness strengthened the willingness to work through fear of failure. This suggests that if you think you are out of business due to market competitiveness, you are more likely to choose to get a job than to start a business. Fourth, those with higher entrepreneurial self-efficiency had less effect of perceived loss on fair of failure than those with lower entrepreneurial loss. In other words, it can be seen that a person with high entrepreneurial self-efficiency is likely to start-up. It is noteworthy that despite the tendency to fail due to market competition and lack of understanding of risks, small business operators were most aware of the loss of social capital. This is presumed to have had the greatest impact on fear of failure because small business owners try to receive funding or business revitalization support through social networks such as acquaintances and relatives. Based on the above results, this study requires sufficient market research to secure a competitive advantage when preparing for start-ups through policy practice suggestions, and suggests ways to reduce financial loss through the establishment of sophisticated business plans.

• Journal of Digital Convergence
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• v.15 no.6
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• pp.121-132
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• 2017

In this study, there is a purpose of research to secure competitiveness through the effective utilization of intangible corporate resources of founded enterprises. For this research, we conducted a survey on the way the customers who used the products of the BI center and founders less than 7 years evaluated the founded company. Schmitt's empirical element was examined as a theoretical background, and it was examined whether these empirical factors and attitudes acted as a preprocess in the decision-making process as a repurchase intention. The Result of research is as follows. First, It clearly indicated that customer experience and search experience affected the degree of re-purchase. Second, customer's experience (use experience, search experience, contact experience) were grasped with significant influence on customer's attitude. Third, we discovered that customer's attitude had mediated between customer's experience (use experience, search experience) and re-purchase. This research suggests that if we manage empirical factors well, we can increase the degree of re-purchase and cope appropriately with the limitations of small and medium enterprises.

• Journal of Korean Neurosurgical Society
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• v.52 no.4
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• pp.372-376
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• 2012

Objective : The purpose of this large prospective study is to assess the association between the disappearance of the lateral spread response (LSR) before and after microvascular decompression (MVD) and clinical long term results over two years following hemifacial spasm (HFS) treatment. Methods : Continuous intra-operative monitoring during MVD was performed in 244 consecutive patients with HFS. Patients with persistent LSR after decompression (n=22, 9.0%), without LSR from the start of the surgery (n=4, 1.7%), and with re-operation (n=15, 6.1%) and follow-up loss (n=4, 1.7%) were excluded. For the statistical analysis, patients were categorized into two groups according to the disappearance of their LSR before or after MVD. Results : Intra-operatively, the LSR was checked during facial electromyogram monitoring in 199 (81.5%) of the 244 patients. The mean follow-up duration was $40.9{\pm}6.9$ months (range 25-51 months) in all the patients. Among them, the LSR disappeared after the decompression (Group A) in 128 (64.3%) patients; but in the remaining 71 (35.6%) patients, the LSR disappeared before the decompression (Group B). In the post-operative follow-up visits over more than one year, there were significant differences between the clinical outcomes of the two groups (p<0.05). Conclusion : It was observed that the long-term clinical outcomes of the intra-operative LSR disappearance before and after MVD were correlated. Thus, this factor may be considered a prognostic factor of HFS after MVD.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.3 no.1
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• pp.73-103
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• 2008

Over the past few years, "business models" has surged into the management vocabulary. But, while it has become quite fashionable to discuss business models, there has been still much confusion about what are business models and how they could make. In fact, business models can serve a positive and powerful role in corporate management. While other authors have recently offered definitions of "business model", none of them appears to be generally accepted. This paper presents the absence of the generally definition of the business models, elements of business model and classify business logic. To help start-up entrepreneurs better understand, found and check business models thus, this paper propose a method of business model, understanding, founding and checking. The dissertation will present an effective business model building method which is necessary for the start-up entrepreneurs to start business. This paper consists of three parts. first is showing the previous study of business model. The second is the re-definition business model and elements based on the first and to present a new method of business model plating and checking for start-up IT (information technology) company's entrepreneurs. The last is application of the methode. This study applied the methode to a company which is located in "DAEDEOK INNOPOLIS"; this company has specialized Information technology.

• Journal of Digital Convergence
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• v.11 no.9
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• pp.55-65
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• 2013

The purpose of this study was to investigate correlations between entrepreneurial intention and entrepreneurship and entrepreneurial success. For that purpose, the study carried out a survey among the students of Graduate School of Business & Entrepreneurship, the students of small business start-up education, and general people and reviewed the previous studies and literature with a focus on the characteristics and capabilities of entrepreneurial intention. The investigator identified the characteristic factors of entrepreneurial intention including entrepreneurial intention, entrepreneurship, entrepreneurial success, education, and mentor, set a research model and hypothesis for their relations with entrepreneurial success, and empirically analyzed and tested them. The empirical analysis results were summarized as follows: first, entrepreneurial methods and abilities of the variables of entrepreneurial intention turned out to have significant impacts on entrepreneurial success. Second, corporation determination, external factor, and internal factor of the variables of entrepreneurship turned out to have significant effects on entrepreneurial success. Third, re-education after success turned out to be the most influential entrepreneurial education factor on entrepreneurial success, which points to a need for constant education after setting up a business. Fourth, practical entrepreneurial mentors had the greatest influences on entrepreneurial success, being followed by successful entrepreneurial mentors and socially successful mentors in the order. One can have a vision to see a further future of his or her business and promote its growth by forming relationships with those who have more knowledge about the line of business and richer experiences in the field. The subjects overwhelmingly had a positive personality, which suggests that those who try to start a business tend to be positive and considerate of others.

• KSBB Journal
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• v.20 no.6
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• pp.453-457
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• 2005

We investigated the effect of sulfate re-addition on hydrogen production under sulfur-deprived condition. When the final concentration of sulfate to cell suspensions($0{\sim}120{\mu}M$) was increased, chlorophyll concentration, culture density, and total amount of $H_2$ produced, increased up to an optimal concentration of $30{\mu}M\;MgSO_4$. Maximum hydrogen volume was 236 mL $H_2/L$ culture at $30{\mu}M\;MgSO_4$. However, the addition of excess sulfate(above $MgSO_4\;60{\mu}M$) delayed the start of hydrogen production and the induction of hydrogenase. Accordingly, the final yield of hydrogen production was reduced. Using these results, we attempted the continuous and sustained hydrogen production by sulfate re-addition($30{\mu}M\;MgSO_4$) using a single C. reinhardtii culture for up to 4 cycles. In total, hydrogen production volume was 625 mL $H_2/L$ culture.