• Macromolecular Research
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• 제13권3호
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• pp.236-242
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• 2005

Three dithioester-derived carboxyl acid functionalized RAFT(reversible addition-fragmentation chain transfer) agents, viz. acetic acid dithiobenzoate, butanoic acid dithiobenzoate and 4-toluic acid dithiobenzoate, were used in the RAFT bulk polymerization of styrene, in order to study the effects of the R-group structure on the living nature of the polymerization. By conducting the polymerization with various concentrations of the RAFT agents and at different temperatures, it was found that the R-group structure of the RAFT agents plays an important role in the RAFT polymerization; the bulky structure and radical stabilizing property of the R-group enhances the living nature of the polymerization and allows the polymerization characteristics to be well controlled.

• Journal of Power Electronics
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• 제16권5호
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• pp.1861-1868
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• 2016

In this paper, a three-phase AC-DC high step-up converter is developed for application to microscale wind-power generation systems. Such an AC-DC boost converter prossessess the property of the single-switch high step-up DC-DC structure. For power factor correction, the advanced half-stage converter is operated under the discontinuous conduction mode (DCM). Simulatanously, to achieve a high step-up voltage gain, the back half-stage functions in the continuous conduction mode (CCM). A high voltage gain can be obtained by use of an output-capacitor mass and a coupled inductor. Compared to the output voltage, the voltage stress is decreased on the switch. To lessen the conducting losses, a low rated voltage and small conductive resistance MOSFETs are adopted. In addition, the coupled inductor retrieves the leakage-inductor energy. The operation principle and steady-state behavior are analyzed, and a prototype hardware circuit is realized to verify the performance of the proposed converter.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.374-377
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• 2001

We have synthesized poly(3-hexylthiophene)(P3HT), which is the most famous conducting polymer and studied the optical properties of P3HT. And then fabricated the device using P3HT as an emitting layer. For the improve of hole injection from ITO electrode to P3HT emitting layer, we use transparent polyaniline(PANI) electrode. In the voltage-current-luminance characteristics of ITO/PANI/P3HT/LiF/Al device which use the PANI film synthesised during 5 cycle, the device turn on at the 2V and the luminance of $218nW/cm^{2}$ obtained at 12V. External quantum efficiency of ITO/PANI/P3HT/LiF/Al increased at 8V than that of ITO/P3HT/LiF/Al device.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.90-91
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• 1998

The influence of gamma-irradiation sterilization on the creep and wear performance of ultra-high molecular weight polyethylene (UHMWPE) was investigated by conducting the dynamic compressive creep tests and pin-on-disc sliding wear tests. The changes of microstructure property, relative crystallinity, oxidation index, percent crosslinking, were also measured and the relationship between these and creep and wear results was discussed.

• 한국정밀공학회지
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• 제22권2호
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• pp.113-119
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• 2005

A crack emanating from an internal electrode or a conducting damage path in ferroelectric ceramic actuators is analyzed. The boundary of the domain switching zone near the edge of the internal electrode in a ceramic multilayer actuator is determined based on the nonlinear electric theory. The stress intensity factor induced by a ferroelectric domain switching under small scale conditions is numerically obtained for flaws of various sizes near the electrode edge. It is found that stress intensity factor near the crack tip depends on the material property of the electrical nonlinearity.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제18권4호
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• pp.283-294
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• 2014

In this paper we study consumption-labor supply decision of an agent who prepares for retirement at a known time in the future. The agent is assumed to have a preference which is represented by the von Neumann-Morgenstern utility function in which the felicity function has constant relative risk aversion over the composite of consumption and leisure. The composite is obtained by the Cobb-Douglas function. A general problem has been studied by Bodie et al. (2004). We contribute to the literature by deriving the Slutsky equations and conducting comparative statics. In particular, we show that wealth effect can exhibit an interesting property depending upon the time until retirement, as the interest rate increases.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권3호
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• pp.180-185
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• 2005

Microstrip antennas generally have a lot of advantages that are thin profile, lightweight, low cost, and conformability to a shaped surface application with integrated circuitry. In addition to military applications, they have become attractive candidates in a variety of commercial applications such as mobile satellite communications, the direct broadcast system (DBS), global positioning system (GPS), and remote sensing. Recently, many of the researches have been achieved for improving the impedance bandwidth of microstrip antennas. The basic form of the microstrip antenna, consisting of a conducting patch printed on a grounded substrate, has an impedance bandwidth of $1\~2\%$. For improvement of narrow bandwidth of microstrip patch, we were designed U-slot microstrip patch antenna in this paper. This antenna had wide bandwidth for all personal communication services (PCS) and IMT-2000. For the design of U-slot microstrip patch antenna using a finite difference time domain(FDTD) method. This numerical method could get the frequency property of U-slot patch antenna and the electromagnetic fields of slots.

• 항공우주시스템공학회지
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• 제3권1호
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• pp.42-46
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• 2009

The 1st development of "Human Powered Aircraft(HPA)" in Korea has been conducting by KAFA(Korea Air Force Academy) from Aug. 2008 to now. HPA is an aircraft powered by directly human energy. The thrust provided by the human power may be the only source and that is weak. Therefore, light weight and strong structure is first requirement. In this paper, treating a basic conceptual design of HPA and material property and material choice for HPA. Also analysing the structure and checking the safety of HPA.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2001년도 가을 학술발표회 논문집
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• pp.29-32
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• 2001

Conductive polymers(CPs) are a relatively new class of organic materials displaying as their foremost property a high conductivity combined with very light weight, flexibility and reasonably facile processability[1]. Due to their high conductivity/weight ratio, they have recently evinced much interest in potential application as EMI shielding screens, coatings or jackets for flexible conductors, rechargeable batteries and as possible substitutes for metallic conductors or semiconductors in wide variety of electrical devices[2]. (omitted)

• 건설안전기술
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• 통권51호
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• pp.75-83
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• 2010

In terms of deregulation requests from business, incidents at construction sites are rapidly increasing after reducing the regular safety training hours. Especially, to prevent incidents through safety trainings for construction site workers, who have lots of hazardous tasks than general manufacturing, is not only to protect property of both the companies and the country but also to increase their profits. That is why there are loud voices regarding that the safety training is a core mandatory to prevent industrial incidents. But, most companies, as soon as the deregulation for safety training is implemented, mitigated conducting safety trainings to prevent incidents. With this, theincidents are currently to be increased and caught in a vicious circle of many incidents at the smaller companies because of their absentmindedness regarding safety training due to their poorness as subcontractors of major companies, comparing to major companies. This study explains that incident factors are roughly divided into technical factor, managerial factor, and educational factor. And, we confirmed that the educational factor led by deficiency safety awareness and knowledge was the major factor.