• Proceedings of the Technology Innovation Conference
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• 1999.06a
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• pp.98-118
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• 1999

This study deals with the knowledge acquisition activities along the growth stages of Korean ventures. This issue is very important in the three reasons. First, the target of the study-new ventures- is a pending issue and can be regarded as the engine of innovation in the Korean economy. Second, venture activities is so dynamic compared to those of the established companies and the study reflects its dynamic features. Third, the knowledge is becoming more important one among various resources, and knowledge management can be a timely issue. The main research questions are as follows : - How does the degree of knowledge domain, vary along the growth stages\ulcorner - Which knowledge domains are more influential on the performance along growth stages\ulcorner Major findings of the study are as follow: First, technological knowledge acquisition effort are most intensive at the start-up stage, while the management knowledge efforts are active at the growth stage. The degree of market knowledge acquisition efforts is almost the same along the stages. Second, the important knowledge domain, which influences on the performance, varies along the stages. The acquisition effort for product technology knowledge is more influential on the sales growth rate and has a negative effect on the return on assets at the start-up stage, while the management knowledge about administration is more influential on the return on assets at the growth stage. Finally the academic contributions and managerial implications of the study are presented and the future research directions are also suggested.

• Knowledge Management Research
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• v.20 no.2
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• pp.197-216
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• 2019

The Korean government has been focusing on supporting technology startups to solve social and economic problems such as low growth, declining economic growth rate, rising youth unemployment rate and lack of new growth engine. Although the failure rate of young technology startups is very high, relevant researches are still scant. On the basis of previous researches, this study has identified four growth factors of technology startups: characteristics of entrepreneurs, technical superiority and originality of business items, focused marketing strategy, and follow-up government support projects. Five young technology startup cases were selected and analyzed in the cosmetics industry which were supported by the Six-month Challenge Platform project of Chungbuk Creation Economic Innovation Center. The main findings of the case study were as follows: First, product development through inhouse R&D rather than external contracted R&D was beneficial to acquiring follow-up government support projects and external investment. Second, choosing a small niche market and concentrating marketing efforts on the target market had a positive effect on firm performance. And, third, relevance of entrepreneurs' college major and technological originality of business items were confirmed to influence firm performance positively in the early stage. The results are expected to help young technology startups survive successfully and establish a foothold for growth in their early stage.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.700-710
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• 2008

A Bubble size distribution model has been developed for the numerical simulation of cryogenic high-speed cavitating flow of the turbo-pumps in the liquid fuel rocket engine. The new model is based on the previous one proposed by the authors, in which the bubble number density was solved as a function of bubble size at each grid point of the calculation domain by means of Eulerian framework with respect to the bubble size coordinate. In the previous model, the growth/decay of bubbles due to pressure difference between bubble and liquid was solved exactly based on Rayleigh-Plesset equation. However, the unsteady heat transfer between liquid and bubble, which controls the evaporation/condensation rate, was approximated by a theoretical solution of unsteady heat conduction under a constant temperature difference. In the present study, the unsteady temperature field in the liquid around a bubble is also solved exactly in order to establish an accurate and efficient numerical simulation code for cavitating flows. The growth/decay of a single bubble and growth of bubbles with nucleation were successfully simulated by the proposed model.

• Journal of Technology Innovation
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• v.19 no.3
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• pp.85-114
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• 2011

This paper aims at developing a new index that represents the Korean new growth industries, which is named the Korea Future Technology Index(KOFTI). The KOFTI is designed to provide a reliable and econometric index based on which the Korean government searches for new growth engines. The KOFTI is composed of three individual indexes such as the Economic Impact Index, the Future Strategy Index, and the Technological Influence Index. The KOFTI is applied for 62 star brands, which have been promoted by the Korean government for the korean future industrial competitiveness. The top 13 leading industries are drawn from the calculation of the KOFTI for 62 star brands.

• Journal of Power System Engineering
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• v.21 no.3
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• pp.85-92
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• 2017

Global air traffic is forecast to grow at an average annual rate of around 5% in the next 20 years. The continuous growth of air traffic and raised environmental awareness put increasing pressure on aero engine manufacturers to reduce fuel burn and emissions. NEWAC are a new integrated program of the European Union with focus on innovative core engine concepts to achieve this problem. In this paper, Within NEWAC, active core engine configurations will be investigated. the investigation is focused on the optimal design of the CAC heat exchanger for active core. For optimal design of he CAC heat exchanger, the HTFS of basic design of heat exchanger are analyzed so as to proceed an optimization routines based on Response Surface Method(RSM) and Design of Experiment(DOE). As a result, CAC heat exchanger optimized by 1.0314 lb/s mass flow rate and 3.9058 mm TP of tube layout and 206.8181 mm height of heat exchanger and 918 tube number for heat transfer and pressure drop. We confirm the design optimization using RSM and DOE is useful on complex structure of heat exchanger.

• Journal of the Korean Society of Visualization
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• v.14 no.3
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• pp.51-58
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• 2016

New concept spark plug was developed to study its influence on the combustion characteristics of SI engine. It has pre-ignition chamber at the lower end of spark plug and flame hole, in which fresh mixture gas can be put in through the flame hole without any fuel supply system. This spark plug was tested in a single cylinder engine dynamometer for different air fuel ratio to measure the fuel consumption rate, emission gases, and MBT timing. And constant volume combustion chamber was made to understand flame characteristics of spark plug. New spark plug induced fast burn compared to the conventional spark plug and its effects were increased in lean air fuel ratio. Pre-ignition chamber spark plug with 5 holes which had adjusted size was more stable and effective in combustion performance than pre-ignition chamber spark plug with 1 hole. And its effects showed larger differences in lean air fuel ratio than stoichiometric condition. Flame kernel and flame growth process of conventional spark plug and pre-ignition chamber spark plug studied by flame visualization of schlieren method.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.2
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• pp.195-200
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• 2015

It is envisaged that the effect of increasingly stricter air emissions legislation implemented through IMO Annex VI and other local air quality controls, together with favorable financial conditions for the use of natural gas instead of liquid fuel oil as a bunker fuel, will see an increasing number of DF engine and single gas fuel engine applications to LNG carriers and other vessel types. As part of provision for the current international movements in the shipping industry to reduce GHG emission in air, new design concepts using natural gas as an alternative fuel source for propulsion of large commercial vessels, have been developed by shipyards and research institutes. In this study, an explosion analysis for a gas supply machinery room of LNG-fuelled container ship is presented. The gas fuel concept is employed for the high pressure ME-GI where a leakage in the natural gas double supply pipe to the engines is the subject of the present analysis. The consequences of a leak are simulated with computational fluid dynamics (CFD) tools to predict typical leak scenarios, gas cloud sizes and possible explosion pressures. In addition, capacity of the structure which is subject to explosion loads has been assessed.

• International journal of advanced smart convergence
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• v.4 no.1
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• pp.54-63
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• 2015

Increasing air pollution levels and the global oil crisis has become a major hindrance in the growth of our automobile sector. Traditional Internal Combustion engines running on non-renewable fuels are proving to be the major culprit for the harmful effects on environment. With few modifications and also with assistance of few additional components current small SI engines can be modified into a pneumatic engine (commonly known as Compressed Air Engines) without much technical complications where the working fluid is compressed air. The working principle is very basic as adiabatic expansion of the compressed air takes place inside the cylinder pushing the piston downwards creating enough MEP to run the crank shaft at decent RPM. With the assistance of new research and development on pneumatic engines can explore the potential of pneumatic engines as a viable option over IC engines. The paper deals with analysis on RPM variation with corresponding compressed air injection at different crank angles from TDC keeping constant injection time period. Similarly RPM variation can also be observed at different injection pressures with similar injection angle variation. A setup employing a combination of magnetic switch (reed switch), magnets and solenoid valve is used in order to injection timing control. A conclusive data is obtained after detailed analysis of RPM variation that can be employed in newly modified pneumatic engines in order to enhance the running performance. With a number of benefits offered by pneumatic engine over IC engines such as no emissions, better efficiency, low running cost, light weight accompanied by optimized injection conditions can cause a significant development in pneumatic engines without any major alteration.

• Journal of Advanced Navigation Technology
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• v.23 no.1
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• pp.44-54
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• 2019

In many countries, there are needs of new transportations to replace ground congestions due to growing number of cars. In addition, the increase in the number of cars held by economic growth will further increase traffic congestion in the future. To overcome this problem, many researches have been performed for personal air vehicle (PAV). In this study, the wing loading and the power-to-weight ratio that are major design parameters for the sizing of roadable PAVs were calculated for different kinds of airfoil and engine types. I.e., in the sizing process, the study was conducted to determine the design point using the graphs of wing loading, power-to-weight ratio, brake horse power, and fuel efficiency for the given mission profiles considering domestic environments and the FAR PART 23 which is the GA class aircraft certification standard. As a result of sizing, using diesel engine require high maximum take-off weight, wing area, and power compared to gasoline engine due to more engine weight.

• Journal of Information Technology Services
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• v.10 no.2
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• pp.119-139
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• 2011

The concept of ubiquitous is being applied on diverse industry fields as a new growth engine in Korea. With constructing u-City, new services which are called 'ubiquitous services' are developed actively. Even though there are active movement to develop u-service, there is no clear definition of what service can be defined as ubiquitous service. Given that this study proposes a u-service value classification framework focusing on services' characteristics. We conducted experts' group interviews to analyze new operating or developing services whether it can be ubiquitous. Study results show that some services are hard to be defined as u-service, so this study offers possible improvement alternative. The u-service value classification which offers clear definition of u-service can be used for the practitioners offering measurement framework of u-service level.