• Transactions of the Korean hydrogen and new energy society
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• v.19 no.3
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• pp.189-198
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• 2008

Cooperative effects of Rh, Ce and Zr added to Fe-based oxide mediums were investigated using temperature programmed redox reaction (TPR/TPO) and isothermal redox reaction in the view point of hydrogen storage and release. As the results of TPR/TPO, Rh was a sale additive to remarkably promote the redox reaction on the medium as evidenced by the lower highest peak temperature, even though its addition was to accelerate deactivation of the mediums due to sintering. On the other hand, Ce and Zr additives played an important role to suppress deactivation of the medium in repeated redox cycles. The medium co-added by Rh, Ce and Zr (FRCZ) exhibited synergistic performance in the repeated isothermal redox reaction, and the amount of hydrogen produced in the water splitting step at 623 K was highly maintained at ca. $17\;mmol{\cdot}g^{-1}-Fe$ during three repeated redox cycles.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.274-276
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• 2002

긴급보호제어시스템(SPS, Special Protection System)은 일반적인 보호동작 범위를 벗어난 외란에 대해서 계통 전지역의 보호를 목적으로 하는 광역시스템 보호기술이다. 따라서 SPS는 외란 시에 계통 장비의 보호보다는 계통을 보호함으로써 전력 공급능력 향상에 주안점을 두게 된다. SPS는 자주 동작하지 않고 평소에는 대기 상태로 있으며, 긴급한 동작이 요구되기 때문에 많은 경우에 그 동작이 미리 결정되어 있다. SPS는 입력변수나 전력계통에의 영향에 따라 분류할 수 있는데, 입력변수에 따라서는 계통 응답에 기초한 SPS와 사고에 기초한 SPS로 나눌 수 있다. 발전기 탈락, 부하 차단이 SPS의 주요 보호 동작이며 이 외에 가스터빈이나 양수발전기 기동, AGC 제어, HVDC 고속전력변환, 분로기기의 자동스위칭 등의 제어 동작이 있다. 우리나라의 경우에는 주로 동기탈조 방지를 위한 발전기 탈락의 동작을 하는 SPS가 설치, 운전되고 있다.

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.234-240
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• 2016

Energetically-modified material using reject fly ash (RFA), generated from thermal power plants, was manufactured to investigate the effect of the material on the physical and chemical characteristics of cement mortar. In order to modify reject fly ash, a vibration mill was used. Particle size, grain shape, and crystal structure of the ash were analyzed. Then, the compressive strength of the mortar using energetically-modified reject fly ash (ERFA) was measured. Microstructure and X-ray diffraction (XRD) patterns were also used in the analysis. As the replacement rate of ERFA increased, the value of the compressive strength tended to decrease. However, it was found that the compressive strength values of 7 and 28 days-cured specimens were higher than those of conventional ordinary Portland cement (OPC) mortar with 10 % replacement rate condition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.43-46
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• 2004

We demonstrated efficient white light emitting OLEDs with a single emissive layer structure, which was blue-emitting 1,4-bis[2,2-diphenylvinyl]biphenyl (DPVBi) doped with blue luminescent amino-substituted distyrylarylene amine (DSA-amine) and red luminescent [2,6-bis[2-[5-(dibutylamino) phenyl]vinyl]-4H -pyran-4-ylidene]propanedinitrile (DADB). Through the optimization of the device structure, the white light emission with full visible spectral range was obtained. Its CIE color coordinates was (0.32,0.42) at 10 $mA/cm^2$ and the external quantum efficiency, the luminance efficiency and the luminance yield were 3.7 %, 3.3 lm/W and 9.0 cd/A, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.106-108
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• 2004

We have investigated the photolithographic patterning method of light emitting polymer film for polymer light emitting diodes (PLED). Blue light emitting polymers based on polyfluorene, which can be cured photochemically to yield an insoluble form, have been synthesized using Ni(0) mediated Yamamoto polymerization. The relationship between patterning property and several variables such as the intensity of the exposed UV light, the concentrations of additives, has been studied by using optical microscope analysis, UV/visible spectroscopy, and photoluminescence. We have successfully fabricated PLEDs composed of the patterned emissive layer and their electroluminescence property has been also investigated. In this presentation, the detailed photolithographic patterning method and its application for polymer light emitting display will be discussed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.939-944
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• 2010

A high voltage air-cored helical strip/wire type pulse transformer has been fabricated for charging of a high voltage pulse forming line. As a primary coil, copper strip of 25mm width was wound helically around a MC nylon cylinder. For a secondary coil, copper enameled wire of 1mm diameter was wound around conical cylinder in order to provide insulation between two windings. The coupling coefficient of 0.53 was obtained when two coils were combined coaxially in the insulation oil filled chamber. Voltage gain and energy transfer efficiency were investigated by varying the parameters of primary and secondary circuit. Test results shows that the voltage gain increases up to 17 with increasing the primary capacitance up to 200nF. And highest energy transfer efficiency of 44% was obtained when the dual resonant operation condition was nearly satisfied. The pulse transformer developed in this study can be used for charging the middle conductor of a Blumlein pulse forming line.

• Journal of Korean Elementary Science Education
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• v.24 no.3
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• pp.310-320
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• 2005

The purpose of this study was to investigate young children's environmental literacy level and variables that affected their environmental literacy. Of the students, 969 in third grade from big cities, medium sized cities and rural areas participated in this study, and their environmental literacy was measured through 69 questions consisted of 24 items for knowledge, 22 for attitude, 16 for behavior, and 7 for skills with 13 demographic variables. Eighty minutes were given to answer the questions. Statistical analysis was conducted on each of the categories (knowledge, attitude, behavior, skill) that make up environmental literacy and multivariate analysis variance (MANOVA) was also conducted to investigate variables that affect environmental literacy. Results indicated that the correlation between attitude and behavior is the highest. Also, it was found that a demographic variable might affect one, two, or sometimes all categories of the environmental literacy.

• The Journal of Korean Academic Society of Nursing Education
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• v.24 no.1
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• pp.50-60
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• 2018

Purpose: This study aims to determine the bioethical subjectivity of nursing students with experience volunteering in elderly care facilities, and the characteristics that comprise the types thereof. Methods: Q methodology, which analyzes the subjectivity of each type, was used. The 37 selected Q statements from 32 participants were classified into the shape of a normal distribution using a 9-point scale. The collected data were analyzed using the PC-QUANL program. Results: The survey revealed that the bioethical subjectivity of nursing students with experience volunteering in elderly care facilities can be divided into three types: a rational dignity emphasis, an autonomous right to life belief, and conflict avoidance. All three attitudes regard human beings as possessing dignity, and life and death as elements to be experienced as aspects of human life. Bioethical values are critical to treatment and care; however, it is sometimes also held that humans have the right to commit suicide. Conclusion: This study enhanced our awareness of nursing students' bioethics. The findings can be used as a basis for the design of differentiated bioethics education according to each type of bioethical subjectivity. This calls for diverse research on bioethics and the implementation of effective bioethics education.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.365-366
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• 2002

A novel TEM resonator coil was developed for the imaging of small animals. The functional elements of the TEM resonator were 8 inner conductors, distributed in a cylindrical pattern and connected at the ends with capacitors to the cylindrical outer shield. The TEM resonator coil with cavity elements was robust to the surrounding influences due to the self-shielding structure. The TEM resonator coil with high Q factor could provide high quality MR images at 3.0T MRI system. Also, the TEM resonator coil has an advantage for a fine tune with length adjustment of each cavity elements. Thus, The TEM resonator coil at 3.0T, even higher field could be used in the research studies.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.2
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• pp.141-147
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• 2015

In this study, a position control algorithm for an omni-directional mobile robot based on Mecanum wheels was introduced and experimentally evaluated. Multiple ultrasonic sensors were installed around the mobile robot to obtain position feedback. Using the distance of the robot from the wall, the position and orientation of the mobile robot were calculated. In accordance with the omni-directional velocity generation mechanism, the velocity kinematics between the Mecanum wheel and the mobile platform were determined. Based on this formulation, a simple and intuitive position control algorithm was suggested. To evaluate the control algorithm, a test bed composed of artificial walls was designed and implemented. While conventional control algorithms based on normal wheels require additional path planning for two-dimensional planar motion, the omni-directional mobile robot using distance sensors was able to directly follow target positions with the simple proposed position feedback algorithm.