• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.159-166
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• 1998

본 연구에서는 공기포일 베어링으로 지지된 로터 베어링 시스템을 구성하고 실험을 수행함으로써 시스템의 진동을 측정하고 그 결과를 해석함으로써 로터 베어링 시스템의 안정성 검토한다. 또, 초기 구동 마찰을 고려하여 공기윤활로만 구동되는 경우와 초기에 베어링 표면에 오일이 도포된 경우를 비교한다. Transient data를 해석 함으로써 로터 베어링 시스템의 startup 및 shutdown에 대한 특성 파악이 가능해지며 시스템의 동적 특성에 대한 더욱 정확한 해석을 가능케한다.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.413-418
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• 1995

A computer code to simulate the letdown system was developed to analyze the hydrodynamic transients. It was found that valve plug characteristics have a significant effect on the system stability, and that the plant specific valve control system setpoints should be determined based on the characteristics of procured valves by using a simulation code, before performing the plant startup test. The letdown system instability was evaluated for the feedback to the design of future plants.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.19 no.2
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• pp.63-79
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• 2024

The startup ecosystem is experiencing a paradigm shift in founding due to the acceleration of digital transformation, online platform companies have grown significantly into unicorns, but the lack of differentiated approaches and strategic support for deep tech startups has led to the inactivity of the startup ecosystem. is lacking. Therefore, in this study, we proposed ways to develop domestic startup development policies, focusing on the US system, which is an advanced example overseas. Focusing on the definition and characteristics of deep tech startups, current investment status, success stories, support policies, etc., we comprehensively analyzed domestic and international literature and derived suggestions. In particular, he proposed specific ways to improve support policies for domestic deep tech startups and presented milestones for their development. Currently, the United States is significantly strengthening the role of the government in supporting deep tech startups. The US government provides direct financial support to deep tech startups, including detergent support and infrastructure support. It has also established policies to foster deep tech startups, established related institutions, and systematized support. It is worth noting that US universities play a core role in nurturing deep tech startups. Leading universities in the United States operate deep tech startup discovery and development programs, providing research and development infrastructure and technology. It also works with companies to provide co-investment and commercialization support for deep tech startups. As a result, the growth of domestic deep tech startups requires the cooperation of diverse entities such as the government, universities, companies, and private investors. The government should strengthen policy support, and universities and businesses should work together to support R&D and commercialization capabilities. Furthermore, private investors must stimulate investment in deep tech startups. Through such efforts, deep tech startups are expected to grow and Korea's innovation ecosystem will be revitalized.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.10
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• pp.801-807
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• 2020

Opening characteristics of a main oxidizer shut-off valve at different valve inlet pressures have been experimentally investigated. The pilot pressure at the moment of the valve opening increases linearly with increasing the valve inlet pressure and the increased pilot pressure reduces the valve travel time. As the pilot pressure increases at the moment of valve opening, the time to start opening the valve is delayed resulting in increasing the valve opening time. With the increment of the valve inlet pressure, the valve opening time is mainly determined by the time required for the pilot pressure to start opening the valve. Therefore the design of a pilot gas supply system can readily control the valve inlet pressure at the valve opening as well as the amount of oxidizer supplied to a combustion chamber during the engine startup.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.11
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• pp.899-905
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• 2014

This paper describes preliminary research conducted for developing a high-efficiency clean large cauldron using the liquid-vapor phase change heat transfer. To improve the isothermal environment of the cauldron, naphthalene and FC-40 were selected as the working fluids to operate well in the temperature range of $100-200^{\circ}C$ and used in experimental investigations of the heat transfer characteristics. A two-phase closed thermosyphon was designed and built to demonstrate the functionality of the working fluids. Startup, boiling, and condensation tests were performed, and the test results were used to examine the possibility of complementary effects of the startup and heat transfer characteristics of the two-phase closed thermosyphon using a mixture of naphthalene and FC-40.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.486-493
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• 2017

Refineries and chemical plants with isolated power systems that have a limited power supply are more susceptible to voltage changes from disturbances compared to power systems connected with a power company. Furthermore, most loads in such cases are induction motor loads, and therefore, transient voltage characteristics when starting a high-capacity motor must be examined. In general, high-capacity motors are customized appropriately to the load performance curve by the manufacturer during the construction of an industrial plant. Subsequently, when complying with the voltage drop permitted by international standards during the design process, power supply equipment such as transformers and generators is overdesigned. Therefore, a novel analysis is necessary on standards for startup and constraint voltage drops, as well as on identifying the voltage drop limitations for starting high-capacity motors in refineries and chemical plants with isolated power systems. In this study, field tests on an industrial plant were conducted, and simulations modeled under conditions identical to those of the field test system were performed using the general-purpose program ETAP in order to compare the results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1084-1087
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• 2017

When a liquid rocket engine is started the oxidizer and fuel must be flowed into combustion chamber and gas generator with time differences. The wrong time difference between propellants or malfunction of ignition device can occur the explosion of combustion chamber due to detonation by energized premixed-propellants. Therefore it is important to observe the transient characteristic of propellants or to measure the inflow time of propellants into combustion chamber and gas generator. The measurement of static pressure is not enough to observe the propellants inflow time into combustion chamber and gas generator. By measuring dynamic pressure of main flow passage of propellants the accurate propellants inflow time could be investigated.

• International Journal of Costume and Fashion
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• v.18 no.2
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• pp.65-83
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• 2018

The purpose of this study was to explore the dynamics of the newly emerging designer fashion market and examine how startup designers reacted to the tension between creativity and business, and how they grew within such dynamics. In-depth interviews were conducted with 22 DFE entrepreneurs and 7 fashion industry experts. The grounded theory was used to analyze data and yield results. Korean new generation of DFEs, attracted by the growing online market opportunities are directly distributing through online channels, targeting the millennial consumers who are pursuing new values at new distribution channels. They show new growth pattern, start with a few key items in the middle and lower price segments, then upscale their design, quality, and price. This study further investigated designers' enterprise orientation shift, which was explored by Mills. Some creativity-oriented designers encountered difficulties in the orientation shift, while designers who demonstrated business characteristics from the startup stage restored the balance by trying to improve both creativity and business. This study discovered a new way for the designer to enter the growth stage. This growth approach is one of the success strategies applicable to designers launching a brand on online platforms in the global market.

• Asia-Pacific Journal of Business
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• v.15 no.1
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• pp.179-192
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• 2024

Purpose - The purpose of this study is to examine the effect of entrepreneurial experience, business model innovation and financing on new venture performance. Design/methodology/approach - This study analyzes survey data on new ventures in Korea and investigated research hypothesis by multiple regression analysis. Findings - Founders' prior startup experience have different impacts on performance depending on whether they had a successful or failed startup. Successful experience has a positive impact on early performance, while failure experience has a negative impact. Business model innovation shows a positive and significant relationship with early performance. External financing has different effects depending on the type of funding source and performance variables. VC funding is positively related to employment creation, while government R&D funding is negatively related to sales volume. Research implications or Originality - This study confirms that the impact of entrepreneurial experience on early performance varies depending on the characteristics of successful and unsuccessful entrepreneurs. It also empirically confirms that business model innovation has a significant impact on early performance. We empirically examine the relationship between various external financing sources of venture firms and early performance. Since the effects of entrepreneurial experience, business model innovation, and external financing on early stage performance may be different, entrepreneurs should consider these relationships when pursuing early stage business opportunities.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.9 no.1
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• pp.79-87
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• 2014

This paper aims to identify determinants of entrepreneurial intentions among college students of a university in Daejeon. We have used a revised Entrepreneurial Intention Questionnaire including personal traits, demographic characteristics, the three factors of the Theory of Planned Behavior (TPB), motivations to startup and planned startup time, and entrepreneurial intentions. The analysis shows that there are strongly significant and positive relationships between the three TPB factors and entrepreneurial intentions of college students. In addition, students' motivations to create a firm such as independence and self-achievement have a positive and significant effect on their entrepreneurial intentions, while the students who want to start their business right after their graduation have significantly higher entrepreneurial intentions than those who want to create a firm after doing a salaried job. Furthermore, students whose parents have created or operated a firm have no significant difference from others, and parents' startup business type are significantly different from their sons and daughters' interested areas of business.