• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 한국전기전자재료학회 2006년도 추계학술대회 논문집 광주전남지부
• /
• pp.53-57
• /
• 2006

In this paper, maxwell 3D finite element analysis program (Ansoft) was used to obtain electromagnetic properties associated with the coil and nearby structures. The electromagnetic emitting properties were presented by 3D simulation software operated at 250 kHz and some specific conditions. The electromagnetic field in the ferrite core was shown to be high and symmetric. An LS-100 luminance meter and a Darsa-2000 spectrum analyzer were used in the experiment. According to data on the lamp tested using high magnetic field ferrite, the optical and thermal wave fields were shown to be high around the ring-shaped electrodeless fluorescent lamp. The optical or light field was high at the center of the bulb rather than around the ferrite core. The light conditions of the bulb were assumed to be complex, depending on the condition of the filler gas, the volume of the bulb, and the frequency of the inverter. Our results have shown coupling between the gas plasma and the field of the light emitted to be nonlinear.

• Transactions of the Society of Information Storage Systems
• /
• 제6권2호
• /
• pp.79-82
• /
• 2010

In optical imaging systems, such as microscopes, high resolution exposure systems, and optical storage devices, higher optical resolution is a requirement. One of the promising technologies that is able to satisfy this requirement with relatively simple construction and reliable performance are, solid immersion lens (SIL)-based near-field (NF) optical systems. High NA optical systems using annular apertures have been investigated as one solution to achieve higher resolutions and an extended focal depth. By applying an optimized annular aperture to convention SIL optical head resolution can be increased by approximately 20%. This novel SIL-based near-field optics will be verified through experiments such as measuring focused beam spot profiles and observing the topology of a measurement sample. The studied SIL-based near-field optics can be applicable to not only next generation optical storage device but also high resolution microscopy and pattering technologies.

• Progress in Superconductivity and Cryogenics
• /
• 제24권3호
• /
• pp.19-23
• /
• 2022

We have been developing a magnetic separation device that can be used in low magnetic fields for paramagnetic materials. Magnetic separation of paramagnetic particles with a small particle size is desired for volume reduction of contaminated soil in Fukushima or separation of iron scale from water supply system in power plants. However, the implementation of the system has been difficult due to the needed magnetic fields is high for paramagnetic materials. This is because there was a problem in installing such a magnet in the site. Therefore, we have developed a magnetic separation system that combines a selection tube and magnetic separation that can separate small sized paramagnetic particles in a low magnetic field. The selection tube is a technique for classifying the suspended particles by utilizing the phenomenon that the suspended particles come to rest when the gravity acting on the particles and the drag force are balanced when the suspension is flowed upward. In the balanced condition, they can be captured with even small magnetic forces. In this study, we calculated the particle size of paramagnetic particles trapped in a selection tube in a high gradient magnetic field. As a result, the combination of the selection tube and HGMS (High Gradient Magnetic Separation-system) can separate small sized paramagnetic particles under low magnetic field with high efficiency, and this paper shows its potential application.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 한국조명전기설비학회 2005년도 춘계학술대회논문집
• /
• pp.228-230
• /
• 2005

Magnetic field has been used to hold plasma at high temperature for a long time. Reverse field has shown unstable process. Using ratio frequency, the author could control the instability of the process and formed a stable erversed field.

• Proceedings of the IEEK Conference
• /
• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
• /
• pp.359-362
• /
• 2003

In PDP(Plasma Display Panel), sub-field method is used to implement gray scale. Each sub-field has different periods. And Every gray level has information of which sub-field has to be displayed. This is called sub-field mapping. There are several sub-field mapping values in some gray levels. So, it is possible to select best choice in this paper, we propose new sub field mapping method using a fuzzy inference system to select best sub-field mapping values in accordance with input image and environment temperature. In order to implement fuzzy system, we used MATLAB fuzzy inference editor.

• Proceedings of the Korea Concrete Institute Conference
• /
• 한국콘크리트학회 1994년도 봄 학술발표회 논문집
• /
• pp.260-265
• /
• 1994

High strength concrete(65MPa) was used for construction of the bulk cement storage silo by using sliding form. This paper presents mix design, production, quality control and experience with field application of high strength concrete under cold weather conditions. It is shown to be possible to produce high strength concrete of compressive strength of 50~60 MPa by using high-range water reducer to lower w/c ratio with appropriate quality control.

• Hwankyungkyoyuk
• /
• 제8권1호
• /
• pp.81-97
• /
• 1995

This study is to consider the result of the Field Trip Contest(FTC) and get a suggestion as a way of environmental education at school level in field. FTC was executed with selected students(3/1team) of 5th grade nationwide at Nam-Han mountain fortress in the suburbs of Seoul in Oct., 1994. The outcome of FTC was very high with the score of 1.38/2.0, and the quality of the program was generally high with the score of 1.09/2.0. Among areas of the outcome domain, accomplishment of the objectives of FTC was very high(1.55), execution of the policy of FTC was generally high(1.27), and operation and promotion of FTC was generally high(1.16). And in the Program of FTC domain, meaning of execution was very high(1.57), possibility of accomplishment was not high(0.03), validity of the content was generally high(1.18), appropriateness of activity scope was generally high(1.15), possibility of application into school system was generally high(1.22), and extending effect to education was generally high(0.9). Participants responded they got a great experience of inquiry for protecting nature during the activity of FTC and teachers accompanying found a good possibility to do in own school province.

• Proceedings of the KIEE Conference
• /
• 대한전기학회 2008년도 학술대회 논문집 정보 및 제어부문
• /
• pp.486-488
• /
• 2008

300 MHz가 넘는 초고자장 MRI에서는 송신 또는 수신 RF Magnetic Field 의 불균일도가 심해져서 이를 개선하기 위한 많은 방법들이 제안되고 있다. 그 중 가장 대표적인 방법은 $4{\sim}32$ 채널의 Transmit Array의 각 채널에 인가되는 전압과 위상을 변화시켜 RF Magnetic Field의 불균일도를 개선하는 방법이다. 본 논문에서는 Transmit Array 내부에서 머리위치의 변화에 따라 RF Magnetic Field ($B_1$ Field) 의 불균일도가 많이 변화하며 이에 따라 RF 송신용 전압과 위상의 Pattern을 새로 최적화 해야 함을 확인하였다. 또한 RF field Mapping을 하기 위해서 Composite RF Sequence를 사용한 Rapid Sequence의 사용과 채널 전압과 위상을 최적화하기 위해서 일반적인 Iterative 방식보다 간편하고 빠른 Target Method를 제안하였다. Driving 패턴의 최적화는 Complex 행렬식을 사용했으며 RF Magnetic Field ($B_1$ Field) 분포는 FDTD 방식으로 계산하였다.

• 한국초전도학회:학술대회논문집
• /
• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
• /
• pp.248-251
• /
• 2000

The fabrication and characteristics of HTS race-track type field coil for generators was carried out. Field coils are composed of 3 pancake coils wound by 37-filamental Bi-2223/Ag-alloy tapes. The winding machine is horizontal type. The critical currents (I$_c$) of the superconducting tapes were measured with variation of bending strain and external magnetic fields. I$_c$ of both whole field coils and 3 pancake coils were measured as a function of temperature. At 77K under the self-field, I$_c$ of whole field coils was 12A, while in the case of middle pancake coil, I$_c$ was 15A. The distribution of magnetic field B was obtained, using 3-D FEM. Our simulation showed that maximums of B${\bot}$A in x-y plane were locally distributed in both the upper and the lower coils. In addition, the fabrication processes and the characteristics of field coil are described.

• International Journal of Knowledge Content Development & Technology
• /
• 제13권2호
• /
• pp.89-104
• /
• 2023

The purpose of this study was to propose ways to improve the library field practice of Department of Library and Information Science to improve the field environment and educational content, enhance students' field practice, increase efficiency, and increase students' satisfaction. To this end, a survey and interview survey were conducted on students who were going to do field training, and the results are as follows. First, students were well aware of what preparations should be made at school before going to field training. Second, students showed high awareness of their rights guarantees and requests for action in the event of problems at field training institutions. Third, students showed a high demand that field training should guarantee the minimum hourly wage. What is an issue in this regard is that policies that can satisfy both the burden of universities for continuous student guidance and evaluation, the burden of training institutions to conduct education while paying practical expenses, and the rights of students to be protected. This study was aimed at students, but it seems that realistic field practice policies should be presented from various angles as research on government ministries or university authorities is added.