• 연구논문집
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• s.28
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• pp.49-58
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• 1998

In order to analyse the scavenging efficiency in a poppet valve type 2-stroke engine. visualization of scavenging flow and quantitative experiments for measuring scavenging efficiency were performed. The effect of shroud angle in RSSV which was developed by KIMM was evaluated under steady flow rig applying single-cycle method. Also dynamic simulator was used by using gas sampling with $CO_2$ and $O_2$gas. The $90^circ$ shroud RSSV was found to be the highest efficient system, and single-cycle and dynamic simulator test are very effective to save time and cost for the development of a 2-stroke engine.

• Journal of Digital Convergence
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• v.19 no.6
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• pp.163-174
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• 2021

This paper investigated the role of CEO leadership in the relationship between Korean small firm's competitive strategy and performance. This study conducted an empirical analysis by collecting data through a questionnaire survey targeting small firms in Korea. The main findings of this study are as follows. First, it was found that the competitive strategies of small firms all had a positive effect on the performance, and it was found that a strategic consistency rather than the type of strategy was positive for firm performance. Second, it was found that the type of leadership of the CEO should also be changed according to the type of strategy. Specifically, it was found that transformational leadership was more appropriate for differentiation strategies, and transactional leadership was more appropriate for cost advantage strategies. This study clarified that the pursuit of a strategic consistency is more important than the type of strategy in the competitive strategy, and that the CEO needs to pursue an appropriate leadership style according to the competitive strategy.

• Korean small business review
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• v.43 no.3
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• pp.21-42
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• 2021

Since R&D (Research and Development) of small companies is becoming more and more important, and government R&D grants are still increasing. This study aims to investigate the factors influencing R&D performance of small companies and necessary capabilities of them. Based on empirical study of 3,636 small companies which participated and completed government R&D grant project, technology innovation capability and technology commercializing capability of small companies are positively related with organizational competences, with moderating effects of entrepreneurship. In addition, their R&D capabilities are not significantly related with R&D commercializing performance directly, but mediated with organizational competences. The results of study suggest implications of measuring the R&D performance of small companies and government support policy with the importance of organizational competences as an intermediate variable of R&D performances.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.28-44
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• 2020

In this paper, the scavenging process of various transfer ports was evaluated to improve the performance of a small two-stroke engine for unmanned aerial vehicles. Three-dimensional computational fluid dynamics simulations were performed to four transfer ports for the evaluation, and a three-phase scavenging model was developed and applied to the simulation results for the quantitative comparison of scavenging performance. the short-circuit of fresh charge was restrained and an in-cylinder turbulent kinetic energy was enhanced by changing the transfer port. Also, a difference in the scavenging for each port were confirmed by applying the three-phase model to the simulation results.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.1
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• pp.57-63
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• 2007

The oxidizer-rich preburner is applied to the high efficiency closed cycle rocket propulsion system. This system is generally operated on oxidizer-fuel mixture ratio over than 50. The spray quality and mixing performance are very important for stable combustion of this preburner. This paper presents basic design concept and spray characteristic of the oxidizer-rich preburner injector and this result could be applied to the development of the oxidizer rich preburner system.

• 베이커리
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• no.3 s.380
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• pp.150-151
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• 2000

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.151.2-151.2
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• 2012

터보펌프 구동에 사용된 가스발생기 생성가스를 연소기로 공급하여 주추력 발생에 사용하는 다단연소 사이클 로켓엔진은 고추력을 요하는 우주 발사체에 널리 사용되고 있다. 다단연소 사이클 로켓엔진에 사용되는 가스발생기를 예연소기라 부르며 케로신과 액체산소를 추진제로 하는 다단연소 사이클 로켓엔진에는 산화제 과잉 예연소기가 사용된다. 예연소기는 터보펌프 구동을 목적으로 하기 때문에 예연소기 생성가스의 횡단면 온도분포는 터빈에 의해 제한되는 온도범위 내에서 균일하여야 하며 넓은 운전영역에서 안정적인 연소가 이루어져야 한다. 산화제 과잉 예연소기는 모든 추진제가 혼합헤드를 통해 분사되는 방식과 추진제를 혼합헤드와 연소실로 나누어 공급하는 방식이 있다. 기술검증을 위해 산화제 일부와 연료를 혼합헤드를 통해 연소실에 공급하여 1차 연소시키고 나머지 산화제를 연소실 냉각채널을 거쳐 연소실 중앙의 분사공을 통해 연소실로 주입하여 기화시키는 형태로 최종적으로 연소압 20MPa, 혼합비 60에서 작동하는 산화제 과잉 예연소기를 설계하여 연소시험을 수행하였다. 혼합헤드에는 별도의 점화용 분사기 없이 전체 연료 분사기를 통해 점화용 연료인 TEA/TEB 혼합물을 분사하여 점화하였다. 추진제를 2단으로 공급할 수 있도록 고안된 가압식 연소시험 설비에서 10회, 누적 60초 이상의 연소시험이 성공적으로 수행되었다. 연소시험결과 넓은 작동영역에서 안정적 연소특성과 생성가스 온도 분포의 균일성을 확인할 수 있었다. 고온 고압의 산화제 과잉 예연소기 기술 확보를 통해 케로신/액체산소 다단연소 사이클 로켓엔진 개발을 위한 기술적 기반을 마련하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.47-53
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• 2006

The oxidizer-rich preburner is applied to the high efficiency closed cycle rocket propulsion system. This system is generally operated on oxidizer-fuel mixture ratio over than 50. The spray quality and mixing performance are very important for safe combustion of this preburner. This paper presents basic concept and spray characteristic of the preburner injector.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07b
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• pp.283-285
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• 2005

단백질들이 어느 세포내 소기관에 위치하는지에 대한 지식은 그들의 기능을 예측하는데 있어서 중요한 정보를 제공한다. 하지만 실험적으로 세포내 소기관 위치를 분석하는 작업은 않은 비용과 시간을 요구한다. 따라서 지금까지 단백질의 세포내 소기관 위치 예측을 위한 다양한 계산적 방법들이 개발되었으나, 효율적인 학습 데이터의 생성에 있어서 문제점을 가지고 있다. 본 논문은 기계학습 기법을 이용하여 주요 서열 구성을 선택함으로써 예측의 성능을 최대화 하는 방법을 제안하고자 한다. 실험은 효모의 단백질의 세포 내 소기관 위치 예측에 있어서 주요 아미노산 서열들을 선택함으로써 예측의 성능을 향상시키는 결과를 보이고 있다.

• Journal of Venture Innovation
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• v.2 no.2
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• pp.47-64
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• 2019

This study analyzed the effects of small business CEO's competencies type on business performance. For this purpose, 4 independent variables(strategic, marketing, management and network competencies) and 2 dependent variables(financial and non-financial performance) were used. 220 data were collected from the field survey questionnaires administered to a convenience sample of small business CEO. For hypothesis testing, the IBM SPSS Statistics 24.0 was used. Frequency analysis, exploratory factor analysis, correlation analysis, and hierarchical regression analysis were conducted. Empirical studies showed as follows. First, this study showed that the four competencies were significant to financial performance and the three competencies(except management competencies) were significant to non-financial performance. The higher small business CEO's competencies, the more likely it affects both the financial and non-financial performance of the company. Second, effects of small business CEO's competencies on financial performance were analyzed in order of network competencies > management competencies > strategic competencies > marketing competencies. Third, effects of small business CEO's competencies on non-financial performance were analyzed in order of network competencies > marketing competencies > strategic competencies. These findings had some implications. In academia, the impact forces of 4 small business CEO's competencies were analyzed for the first time. In practices, successful start-ups or sustainable management requires an interest in the active enhancement of small business CEO's competencies.