• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.2
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• pp.1-8
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• 2017

In order to analyze combustion characteristics of methane-oxygen diffusion flame in a model combustor, combustion experiments were carried out under various spray conditions of propellant scrutinizing combustion stability limit and flame shapes. As the propellant approached the theoretical equivalence ratio condition, a stable detached flame was observed even under high oxygen Reynolds number. And the length of the visible flame increased and the lift-off distance of the flame exhibited a tendency toward decrease. Due to the swirl effect of the propellant by the swirl-coaxial injector, a wide and short flame was produced. Thus, it may be appropriate to employ the swirl-coaxial injector in thrusters having a limited physical dimension.

• The Journal of Korean Association of Computer Education
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• v.8 no.5
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• pp.63-72
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• 2005

The purpose of this study is finding factors affecting the decision of Web-based learning system (Edunet) use and searching for ways to diffuse Edunet use. Based on the diffusion of innovations theory and the results of the previous studies about web-based instruction, seven predictors influencing the decision of Edunet use were extracted. Seven variables as the followings; (1) perceived attributes of innovation (Relative Advantage, Compatibility, Complexity) (2) Innovativeness (3) Self-efficacy (4) Subjective Norm (5) Support. The participants were 315, 5-6th grade elementary school students, and the questionnaire was 20-item with 7-point Likert scales. To analyze the collected data and test the hypothesis, binary logistic regression was employed. The result indicated that the fitness of regression model including seven decision factors was proved. In addition, two factors, subjective norm and support, were identified as the important decision factors of Edunet use.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.5
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• pp.828-836
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• 1987

The inclusion of thermophoresis in particle deposition studies has often been treated separately from deposition due to flow characteristics. Also previously reported experimental results on thermophoresis have been studied in the regions of relatively small temperature gradients. In this study, using real-time laser light reflectivity method, we measured the angular dependence of the deposition rates of particles of the cylindrical collector surface, which immerged in laminar flow of a hot gas suspension of small particles. And we extended the previous narrowband results of thermophoretic deposition rates to the regions of large temperature gradients between the hot gas stream and the collector surface. Based on the obtained data, the cylinder's forward stagnation-point region is considerably enriched in particle 'phase' density owing to the compressibility effect, which leads to locally enhanced deposition while the downstream region from the stagnation point inertial force acts in the opposite direction, which tends to centrifuge particles away from the wall, thus the local deposition rates by thermophoresis are reduced.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.8
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• pp.1487-1493
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• 2016

The susceptible, exposed, infectious, and recovered model (SEIR) is used extensively in the field of epidemiology. On the other hand, dissemination information among users through internet grows exponentially. This information spreading can be modeled as an epidemic. In this paper, we derive the mathematical model of SEIR in viral communication from the view of optimal control theory. Overall the methods based on classical calculus, In order to solve the optimal control problem, proved to be more efficient and accurate. According to Pontryagin's minimum principle (PMP) the Hamiltonian function must be optimized by the control variables at all points along the solution trajectory. We present our method based on the PMP and forward backward algorithm. In this algorithm, one should integrate forward in time for the state equations then integrate backward in time for the adjoint equations resulting from the optimality conditions. The problem is mathematically analyzed and numerically solved as well.

• Journal of Digital Convergence
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• v.10 no.11
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• pp.225-234
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• 2012

OSS(Open source software) pursues the freedom to have access to open source and offers several advantages, over the proprietary software, to enterprises. Based upon Rogers(1995)' innovation-diffusion process, we assume that attributes of innovations includes five characteristics of innovations: relative advantage, compatibility, complexity, trialability, and observability, and that firms' perceptions of these characteristics predict the rate of adoption of OSS. To test this hypothesis, we presents a survey result from 201 companies and institutions concerning the use of OSS. Statistical analysis shows that adoption is highly correlated with each of those characteristics of innovations, but the regression analysis indicates that only compatibility and observability have effects on the adoption of OSS. This implies that intrinsic value of OSS is important, but unless the appropriate service package for improving IT environment is provided, it is not easy to change the perspective of corporate customers more favorable toward OSS use. As a conclusion, the academic and practical implications are also discussed.

• Journal of Korea Technology Innovation Society
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• v.14 no.spc
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• pp.1256-1284
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• 2011

Although a existing consumer market have been studied in depth in the new technology product market, the market research on the overall level of value chain to consist of consumers, distributors, and manufacturers is weak. Therefore, in this paper consumers' purchase of new technology products were simulated and analyzed by a consumer selection model and a multi-agent model, which consist of consumers, distributors and manufacturers. Our research was focused on customer preference study in new technology product market by using conjoint analysis and discrete choice model. And changes in consumer behavior based on adoption of new technologies and offering of incentives were analyzed by ABM (Agent-based Model). In conclusion, the market share of technology products was risen when provision of incentives corresponding to inventory level and demand for new technology products occurred at the same time.

• Journal of the Korean Institute of Telematics and Electronics
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• v.7 no.2
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• pp.33-42
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• 1970

This report is concerned with the fahrication with the falricationof silicon VVC diode by the double diffusion planer technique. At first, some design charts for VVC diode were derived by considering the voltage-capacitance relations, the critical field intensity at the metallurgical junction, and the cut-off frequency of the diode. These charts enables the fabrication engineers to design VVC diode easily without going into the sophisticated design theory. We started with a 2.5 ohm-cm n-type epitaxial silicon wafer. The phosphorous was diffused by POCl3 impurity source. Then boron diffusion followed make hyperabrupt p-n junction by BN source. The maximum to minimum capacitance ratio of the diode as a tuning diode for a TV tuner made in these experiments was 4:1. Measured electrical characteristics of the sample diodes showed in good agreement with the theoretical expectations. Slicing and polishing technique of the silicon wafer and diffusion technique of the impurity atoms, which were employed in our study, are also stated briefly in this report.

• Korean Journal of Food Science and Technology
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• v.12 no.2
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• pp.133-139
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• 1980

The extraction mechanism and extraction conditions of cellular lipid of freeze-dried cells of Rhodotorula rubra YUFE 1526, which was reported as coenzyme Q producing microorganism, were studied. 1. Methyl alcohol was the most appropriate solvent for extraction of cellular lipids and the resulting total lipid was 19.17 weight %. 2. When 1 % (w/v) of freeze-dried cell was extracted by methyl alcohol, the extraction yield was 90.49 % at $50^{\circ}C$ for 2 hr. 3. The diffusivity varied with extraction temperature and the empirical equation was derived as follows : $2.2e^{0-02907T}{\times}10^{-9}\;mm^2/min.$ 4. The diffusivity of cellular lipid of Rhodotorula rubra YUFE 1526 was $9.4{\times}10^{-9}\;mm^{2}/min.$ 5. The extraction model was well fitted on the extraction of cellular lipid.

• Journal of Science and Technology Studies
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• v.14 no.1
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• pp.3-33
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• 2014

Over the last forty years, the dominant perspective of social science on medicine has been the medicalization theory. It indicates the social process of expanding power of medical professionals by (re)defining the problems which were treated as non-medical phenomena(e.g. homosexuality, alcoholism, obesity, etc.) into "diseases" and thus the spheres of medical intervention. Meanwhile, rapid technoscientific changes in the medical field owing to the diffusion of biological sciences and information technologies since the mid-1980s and the accompanying emergence of new social arrangements such as bioeconomy and biological citizenship have led to the rise of a new social scientific perspective called the biomedicalization theory. This paper attempts to compare the two theories and assess their merits and demerits as a basic work to deepen the understandings of sociology and STS on contemporary medicine. And it also attempts to analyze their relative relevance through the case of mental disorder. The analysis on the case of mental disorder clearly shows that the medicalization in that area seems to have continuously proceeded since the early 19th centiry to the present. Furthermore, it also seems true that the five central processes of biomedicalization(except for risk surveillance technologies of mental disorder) have been observed and realized since the late 20th century. These results indicate that although medicalization has consistently proceeded, it has not been limited to the quantitative expansion of the medical field but been extended to the qualitative transformation asserted by the biomedicalization theory. Therefore, while the concept of medicalization is valid and significant even today, we can recognize that the concept of biomedicalization allow us to capture the new phenomena which cannot be properly and sufficiently captured by that of medicalization.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.13 no.4
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• pp.49-58
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• 2018

In recent years, various studies have been carried out on various types of entrepreneurship and comparative activities according to policy efforts and support such as the activation of a bachelor's degree in the establishment of a university, and attention has been paid to the fact that the participation and the educational effect of the students may be different depending on the type. The purpose of this study is to investigate entrepreneurial motivation, entrepreneurship, and entrepreneurial intention in the case of experiential entrepreneurship class focusing on the theoretical-oriented general entrepreneurship class, And the effect of entrepreneurship on entrepreneurial intention. The data were collected and empirical analysis was conducted to compare the difference between the two groups. The results of this study are as follows: First, out of the motivation factors of entrepreneurs, entrepreneurship education, achievement desire, human network, self - esteem, etc. We can confirm that the motivation of entrepreneurs is recognized more greatly. Second, the entrepreneurship factor was not significantly different from the perception between experiential entrepreneurship lecture and theoretical entrepreneurship learner. Third, experiential entrepreneurship learner perceived more willingness to start business than theoretical entrepreneurship learner. Finally, among the entrepreneurship motivation factors, among the entrepreneurship education, achievement desire and entrepreneurship factor, the risk sensitivity affects the entrepreneurial will. This study suggests that the direction of entrepreneurial education focused on quantitative expansion and the creation of qualitative effects of entrepreneurship education are needed. In the future, it will provide policy implications for revitalizing experiential entrepreneurship education In addition, it can contribute to the diffusion of research on the effect of entrepreneurship education.