• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.793-797
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• 2003

Switching PFC converters are widely used not only to comply the power quality specification but also for maximum efficiency. However switching PFC converters generate serious electromagnetic interference (EMI). In this paper to solve this problem, we applied the APW(Anti Phase Winding) and RPWM(Ran-dom PWM) technique to PFC boost converter and obtained satisfactory results. Simulation and experimental results show the improved harmonic and reduced EMI effect in air-conditioner system.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.18-24
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• 2017

Appropriate selection of the starter is essential for successful starting of the gas-turbine engine. Thus, aerodynamic drag during starting phase should be analyzed to assess the feasibility of the starter. In this paper, aerodynamic drag is modeled based on the speed profile from the engine coast down test, and it is scaled with respect to the target engine by comparing the compressor load. Afterward, the govern equation of the starting phase is developed with the torque model of the starter, and the design scheme to select the feasible starter will be finally suggested. The proposed model of starting phase will be useful to perform a preliminary design of the starting system of the gas-turbine engine.

• Journal of Korean Society for Quality Management
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• v.47 no.1
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• pp.187-198
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• 2019

Purpose: In this study, a reliability prediction based reliability growth management is suggested especially for the early development phase of a system and the case study of surveillance system is given. Methods: The proposed reliability prediction based reliability growth management procedures consists of 7 Steps. In Step 1, the stages for reliability growth management are classified according to the major design changes. From Step 2 to Step 5, system reliability is predicted based on reliability structures and the predicted reliabilities of subsystems (Level 2) and modules (Level 3). At each stage, by comparing the predicted system reliability with that of the previous stage, the reliability growth of the system is checked in Step 6. In Step 7, when the predicted value of sustem reliability does not satisfy the reliability goal, some design alternatives are considered and suggested to improve the system reliability. Results: The proposed reliability prediction based reliability growth management can be an efficient alternative for managing reliability growth of a system in its early development phase. The case study shows that it is applicable to weapon system such as a surveillance system. Conclusion: In this study, the procedures for a reliability prediction based reliability growth management are proposed to satisfy the reliability goal of the system efficiently. And it is expected that the use of the proposed procedures would reduce, in the test and evaluation phase, the number of corrective actions and its cost as well.

• Bulletin of the Korean Chemical Society
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• v.28 no.11
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• pp.2003-2008
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• 2007

The aminolysis of diphenyl thiophosphinic chloride (2) with substituted anilines in acetonitrile at 55.0 oC is investigated kinetically. Kinetic results yield large Hammett ρX (ρnuc = ?3.97) and Bronsted βX (βnuc = 1.40) values. A concerted mechanism involving a partial frontside nucleophilic attack through a hydrogen-bonded, four-center type transition state is proposed on the basis of the primary normal kinetic isotope effects (kH/kD = 1.0-1.1) with deuterated aniline (XC6H4ND2) nucleophiles. The natural bond order charges on P and the degrees of distortion of 42 compounds: chlorophosphates [(R1O)(R2O)P(=O)Cl], chlorothiophosphates [(R1O)(R2O)P(=S)Cl], phosphonochloridates [(R1O)R2P(=O)Cl], phosphonochlorothioates [(R1O)R2P(=S)Cl], chlorophosphinates [R1R2P(=O)Cl], and chlorothiophosphinates [R1R2P(=S)Cl] are calculated at the B3LYP/ 6-311+G(d,p) level in the gas phase.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.2
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• pp.12-19
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• 2022

Propellant grains with embedded metal wires have been used for enhancement of burning rate while maintaining high loading density. For the performance design of a solid rocket motor using propellant grain with embedded metal wires, burn-back analysis is required according to number, location, arrangement angle of metal wires, and augmentation ratio of the propellant burning rate near a wire region. In this study, a numerical method to quickly calculate a burning surface area was developed in response to the design change of the propellant grain with embedded metal wires. The burning surface area derived from the developed method was compared with the results of a CAD program. Error rate decreased as the radial size of the grid decreased. Analysis for characteristics of burning surface area was performed according to the number and location of metal wires, the initial and final phases were shortened and the steady-state phase was increased when the number of metal wires increased. When arranging the metal wires at different radii, the burning surface area rapidly increased in the initial phase and sharply decreased in the final phase compared to the case where the metal wires were disposed in the same radius.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.202-210
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• 2014

This paper is to discover selection indicator for academia-industrial cooperation R&D project. Existing Project lacks careful consideration for participant enterprise. But, This project must be focused on enterprise for the goal of project is to improve business competition. Therefore, we analyze the survey result of enterprise satisfaction and deduct the factor of satisfaction by statistical analysis like One-way ANOVA and Regression. The study says that collaboration time, the time of planning of commercialization, technology transfer and the level of goal achievement improve enterprise satisfaction. And it implies needs for plan of manpower input and commercialization at the selecting phase. This paper is significant that it can improve project system by satisfaction. We expect that this result is utilized by planning and management.

• Journal of Technology Innovation
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• v.22 no.4
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• pp.199-233
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• 2014

This paper attempts to investigate how and why the additionality effects occur in the case when a firm receives government subsidy as opposed to counterfactual situation. To demonstrate this, we selected 12 SMEs(small and medium enterprises) firms in Daejeon area and have conducted multiple case studies. In order to analyse the multiple cases of firms, we classified firms innovative activities into three stages which are composed of input, behaviour and output stages and related various factors. Furthermore, we investigated the differences according to types of firms and stages of firm growth. Empirical results show that various input, behaviour and output additionality effects exist when firms receive public subsidies. Compared to companies in the growth and mature stages, startup phase companies depend on government subsidy extensively and they use public subsidies strategically to develop new product and to change their strategic direction. The attitude of firms to use government subsidies is different according to their types and stage of growth as well.

• Journal of Applied Biological Chemistry
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• v.50 no.4
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• pp.244-248
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• 2007

The contents of total phenol and total flavonoid of artichoke (Cynara scolymus L.) were measured. The antioxidant activity of the artichoke was evaluated based on its potential as a scavenging the ABTS radical. These results showed the antioxidant activity of artichoke has a close relationship with the total flavonoid content. The compound showing antioxidant activity was isolated from the artichoke by repeated column chromatography and recrystallization. Based on the spectrometric studies, the compound was identified as 1,3-dicaffeoylquinic acid, known as cynarin. The content of cynarin from heads and leafs of the artichoke determined by $C_{18}$ reversed phase HPLC (high-performance liquid chromatography) coupled with photodiode array detector was 10.15 and 0.67 mg/g, respectively. This compound showed potent antioxidant activities against DPPH and ABTS radicals ($EC_{50}$ = 14.09 and 28.85 ${\mu}M$, respectively).

• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.6-16
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• 1998

Ceramides are currently emerging as the major skin care ingredients due to !heir barrier properties in the stratum corneum of the human skin. Thus, major cosmetic companies have developed synthetic ceramide analogs for their own use. In this study, several ceramide mimic compounds , new skin barrier lipids, were designed and synthesized, and their physical and biological properties were investigated to evaluate their skin care capability. Several structures were designed from the variation of hydrophobic alkyl chain and hydrophilic moiety by the use of molecular modeling software. The selected targets were synthesized, and their properties and activities were studied as the pure form, in the emulsion, or in the lamellar mixture containing cholesterol and fatty acid. Some compounds, such as 1,3-bis(N-(2-hydroxyethyl)-palmitoylamino)-2-hydroxypropane, enhanced the restoration of skin barrier damaged by SDS(sodium dodecyl sulfate), and by acetone treatment. The rate of restoration was comparable to that of natural ceramides. The synthesized compounds alleviated SDS induced skin irritation and facilitated lamellar phase liquid crystal formation. The treatment of 1,3-Dis(N-(2-hydroxyethyl)-palmitoylam ino)-2-hyd roxypropane on the acetone damaged skin revealed that the compound promoted the recovery of intercellular lipid lamellar structure of stratum corneum layer. The replacement of palmitoyl groups of the compound with shorter alkyl chain gave lower emulsion viscosity and liquid crystal density, suggesting easier formulation and poorer barrier activity. Most of the synthesized compounds were non-irritable in various toxicological tests proving that they can be safely introduced to the skin care formulations.

• Journal of Digital Convergence
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• v.8 no.2
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• pp.203-216
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• 2010

This study corresponds to an exploratory survey that identifies and organizes important decision factors for establishing R&D strategic portfolio in the application of digitalized Korean human-dataset. In the case of countries that have performed the above, the digitalized human-dataset and its visualization application development research are regarded as strategic R&D projects selected and supervised in national level. To achieve the goal of this study, we organize a professional group that reviews articles, suggests research topics, considers alternatives and answers questionnaires. With this study, we draw and refine the detailed factors; these are reflected during a strategic planning phase that includes R&D vision setting, SWOT analysis and strategy development, research area and project selection. In addition to this contribution for supporting the strategic planning, the study also shows the detailed research area's definition/scope and their priorities in terms of importance and urgency. This addition will act as a guideline for investigating further research and as a framework for assessing the current status of research investment.