• 한국정밀공학회지
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• 제22권10호
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• pp.121-128
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• 2005

The research on electromagnetic shielding has been advanced for military applications as well as for commercial products. Utilizing the reflective properties and absorptive properties of shielding material, the replied signal measured at the rear surface or at the signal source can be minimized. The shielding effect was obtained from materials having special absorptive properties and structural characteristics such as stacking sequence. Recently researchers studied the electromagnetic properties of nano size particles. In this research {glass fiber}/{epoxy}/{nano particle} composites(GFR-Nano composites) was fabricated using various nano particles, and their properties in electromagnetic shielding were compared. For the visual observation of the nano composite materials, SEM(Scanning Electron Microscope) and TEM(Transmission Electron Microscope) were used. For the measurement of electromagnetic shielding, HP8719ES S-parameter Vector Network Analyser System was used on the frequency range of 8 GHz${\~}$12GHz. Among the nano particles, carbon black and Multi-Walled Carbon Nano-Tube (MWCNT) revealed outstanding electromagnetic shielding. Although silver nano particles (flake and powder) were expected to have effective electromagnetic shielding due to their excellent electric conductivities, test results showed little shielding characteristics.

• Journal of Magnetics
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• 제8권1호
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• pp.18-23
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• 2003

In our previous work, microstructure and magnetic properties of two-phase exchange-coupled $Sm_2Fe_{15}Ga_2C_{x}$/$\alpha$-Fe nanocomposites have been investigated by means of x-ray diffraction, transmission electron microscopy and magnetization measurement. It was found the exchange coupling between the magnetically hard phase $Sm_2Fe_{15}Ga_2C_{x}$ and the magnetically soft one ${\alpha}$-Fe results in an enhancement of the remanence. The sizes of crystallites of both phases are, however much larger than the Block domain-wall width of the magnetically hard phase. This microstructure gives rise to a concave demagnetization curve and consequently reduces the maximum energy Product. In order to improve their magnetic properties, a few Percent of Zr, which may be effective to refine the microstructure through rapid quenching, was introduced into the nanocomposites. The addition of Zr was found to improve the magnetic properties significantly, Under optimum heat-treatment conditions, the remanence, coercivity and maximum energy Product increase from 0.65 T, 0.48 T and 50 kJ/$m^{3}$ for the Zr-free sample to 0.72 T, 0.77 T and 71.6 kJ/$m^{3}$ for the 1 at.% Zr-containing one, respectively, The improvements of magnetic properties are due to the refinement of microstructure by the addition of Zr.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 방전 플라즈마 유기절연재료 초전도 자성체연구회
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• pp.133-137
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• 2004

In this paper, we investigated impurities content, absorption properties, and thermal properties showing by changing the content of carbon black which is semiconductive materials for underground power transmission. Specimens were made of sheet form with the three of existing resins and the nine of specimens for measurement. Impurities content of specimens and absorption properties were measured by ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer) and Karl Fisher. And high temperature, heat degradation initiation temperature, and heat weight loss were measured by TGA (Thermogravimetric Analysis). The dimension of measurement temperature was 0$[^{\circ}]$ to 800$[^{\circ}]$, and rising temperature was 10$[^{\circ}/min]$. Impurities content was highly measured according to increasing the content of carbon black from this experimental result also absorption amount was increased according to these properties. Specially, impurities content values of the A1 and A2 of existing resins were measured more than 4000[ppm]. Heat degradation initiation temperature from the TGA results was decreased according to increasing the content of carbon black. All over, heat stabilities were EEA>EBA>pEVA. That is, heat stabilities of EVA containing the weak VA(vinyl acetate) against heat was measured the lowest.

• 한국전기전자재료학회논문지
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• 제21권11호
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• pp.1036-1041
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• 2008

According to previous report, aged sleeves of old transmission line showed several defaulted installation patterns, which was biased or corrosive-fractured of steel sleeve installed cases. These defects can cause serious accidents such as rapid increasing of sag or falling out of overhead conductor from sleeves. Consequently, the defects lead to the major power outage. Corrosion of steel sleeve is a typical defect by aging of sleeves. And it occupied almost 25 percent of investigated aged sleeves. This paper studied thermal properties and tension for ACSR conductor in case of fractured steel sleeve model by corrosion. The temperature distribution within overhead conductor has a specific gradient. Thermal properties of splice connectors(sleeve and clamp) showed normal behavior. However, mechanical properties were worse than normal sleeves. The detailed results were presented in the text.

• 헤리티지:역사와 과학
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• 제44권4호
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• pp.18-41
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• 2011

1962년 문화재보호법이 제정되면서 무형문화재 보호가 시작되었다. 우리의 무형문화재 보호제도는 일본의 문화재보호법에 근거하고 있다. 일본은 1954년 기 예능 보유자를 인정하는 중요무형문화재 지정제도를 시작으로 지금까지 중요무형민속문화재, 선정보존기술, 기록작성 등 4가지의 무형문화재 보호제도를 채택하여 다원화된 제도를 운영하고 있다. 반면에 한국은 무형문화재 보호제도를 도입하면서 일본으로부터 벤치마킹한 중요무형문화재 지정제도 하나만을 지금까지 운영하고 있다. 중요무형문화재 보유자 인정제도로 특징되는 우리의 무형문화재 보호제도는 무형문화재 종목의 기예를 발현하는 기 예능 보유자를 인정하고, 그 보유자가 전승자를 양성하는 것을 목적으로 하는 보호제도이다. 그 결과 전승자의 확산 및 이와 관련한 관계기관의 설립 등 무형문화재를 전승하는 내재적인 기반을 구축하였다. 그러나 전승자를 중심으로 한 보호제도가 50여 년간 지속되면서 종목 지정의 한계성, 파편화된 지정방식, 무형문화재의 문화 권력화, 종목지정(보유자 인정)조사 평가방식 등 무형문화재의 보호방법과 전승현실의 난맥상이 지적되고 나아가 무형문화재 전승의 진정성 문제와 관련하여 보호제도 자체의 정당성 문제 등 제도에 대한 다양한 문제가 제기되고 있다. 따라서 본 글은 무형문화재 보호제도에 대한 이러한 문제제기와 그 원인을 검토하기 위하여 그간의 제도 이행과정과 성과를 고찰하고자 하였다. 문화재위원회 회의자료, 문화재 정책 담당자, 문화재위원 전문위원들의 저술 등을 기초 자료로 활용하여 제도운영의 전반적인 사항보다는 제도의 핵심인 중요무형문화재 지정(보유자 인정)과 관련한 내용을 중심으로 살펴보았다. 그리하여 특정 기 예능 보유자의 존재가 전제되어야 무형문화재 종목 지정이 가능하므로 현실적으로 무형문화재 보호범위를 확대하기 어려운 제한성, 보유자를 정점으로 한 위계적 폐쇄적 전승구조로 인해 다수의 전승자 접근이 제한되는 문제점 그리고 무형문화재 전승원리로 채택한 '원형' 개념이 무형문화재의 실제전승과 맞지 않는 부적합성 등을 현제도의 문제점으로 상정하고, 이러한 문제점이 중요무형문화재 보유자 인정제도에 뿌리를 두고 생겨난 것임을 밝혀서 향후 우리 무형문화재 보호제도의 확장을 위해 보유자 인정제도는 반드시 개선되어야할 제도이고 그 외에 다원화된 보호제도가 수립되어야함을 강조하였다.

• 한국지반공학회논문집
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• 제20권5호
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• pp.79-86
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• 2004

지반과 숏크리트 사이의 인터페이스 특성은 지반하중이 숏크리트 라이닝에 전달되는 과정에서 중요한 역할을 한다. 또한 인터페이스 특성은 지반 및 숏크리트 라이닝의 거동에 상당한 영향을 미친다. 그러나 대부분의 수치 해석적 연구에서는 이러한 인터페이스 특성을 단순히 가정하여 적용해 왔으며 이를 규명하기 위한 시도도 거의 이루어지지 않았다. 따라서 본 연구에서는 터널 측벽에서 회수된 숏크리트/암석 코어에 대해 직접전단시험과 인터페이스 수직압축시험을 실시하여 점착력, 인장강도, 마찰각, 전단강성 및 수직강성과 같은 인터페이스 특성을 규명하고자 하였다. 인터페이스 특성의 시간 의존적인 변화양상과 비교하기 위하여 압축강도와 탄성계수와 같은 숏크리트의 역학적 물성도 측정하였다. 실험결과로부터, 지반과 숏크리트 라이닝 사이의 인터페이스 특성은 역학적 물성과 유사하게 상당한 시간 의존적 거동을 보인다는 것을 확인하였다. 또한 인터페이스 특성의 시간의존적인 거동을 지수함수와 로그함수 형태로 잘 근사 시킬 수 있었다.

• 한국실내디자인학회논문집
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• 제40호
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• pp.165-171
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• 2003

The findings of this study indicate that intangible cultural properties are worth preservation and transmission and should be considered as very important as tangible cultural properties. If the studies of intangible cultural properties are continued focusing on their characteristics and formational system, they can be expressed more properly by adding new interactive elements to database and expressive requisites. New techniques introduced in this study are believed to provide people with most reasonable and developmental motives for expression of the existing intangible cultural properties. Concerning Korea's cultural properties centered on intangible cultural properties, information construction should be made with a new idea of information based on database from the previous studies. The result will be able to set an important factor to give wide publicity to our cultural identity, which is currently shown in the process of background communication, and serve as a foothold to deliver exact information to our descendants. The intangible cultural properties are our people's mental cultural heritage resources. If museums or initiator groups, which are organized to spread cultural heritages, can use them as the subjects of exhibition through information construction and visualization, it will function to maximize the educational effect of transmitting our national mental world. The development of digital environment will provide the optimum conditions and tools making it possible to visualize intangible forms and ideas in a virtual cyber space. Given these viewpoints, steady studies and efforts for the improvement of Korea's cultural image should be made in the way of intangible cultural properties as well as tangible ones. They start from the country's accurate appreciation of cultural properties and are embodied in systematic adjustment and relationship between interdependent elements.

• 한국실내디자인학회논문집
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• 제13권3호
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• pp.179-186
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• 2004

The findings of this study indicate that intangible cultural properties are worth preservation and transmission and should be considered as very important as tangible cultural properties. If the studies of intangible cultural properties are continued focusing on their characteristics and formational system, they can be expressed more properly by adding new interactive elements to database and expressive requisites. New techniques introduced in this study are believed to provide people with most reasonable and developmental motives for expression of the existing intangible cultural properties. Concerning Korea's cultural properties centered on intangible cultural properties, information construction should be made with a new idea of information based on database from the previous studies. The result will be able to set an important factor to give wide publicity to our cultural identity, which is currently shown in the process of background communication, and serve as a foothold to deliver exact information to our descendants. The intangible cultural properties are our people's mental cultural heritage resources. If museums or initiator groups, which are organized to spread cultural heritages, can use them as the subjects of exhibition through information construction and visualization, it will function to maximize the educational effect of transmitting our national mental world. The development of digital environment will provide the optimum conditions and tools making it possible to visualize intangible forms and ideas in a virtual cyber space. Given these viewpoints, steady studies and efforts for the improvement of Korea's cultural image should be made in the way of intangible cultural properties as well as tangible ones. They start from the country's accurate appreciation of cultural properties and are embodied in systematic adjustment and relationship between interdependent elements.

• 대한전자공학회논문지TC
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• 제48권2호
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• pp.95-104
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• 2011

본 논문에서는 complementary 나선형 공진 구조와 인터디지털 구조 기반의 메타물질 전송 선로가 전압 제어 발진기의 위상 잡음을 줄이기 위해서 제안되었다. 이와 같은 메타물질 전송 선로는 접지 면에 식각된 complementary 나선형 공진 구조의 배열과 신호 면의 인터디지털 전송 선로를 적용하여 구현되었다. 신호 면의 인터디지털 전송 선로는 인터디지털 구조가 없는 일반적인 전송 선로보다 더 높은 공진 Q 특성을 얻기 위해서 사용되었다. 제안된 메타물질 전송 선로의 공진 특성과 Q 특성의 고유 포화 특성이 신호 면의 전송 선로의 폭, complementary 나선형 공진 구조의 크기, complementary 나선형 공진 구조 사이의 전류 방향, complementary 나선형 공진 구조의 단위 셀 쌍의 수를 변화시킴으로써, 그리고 인터디지털 구조의 유무에 의해서 분석되어졌다. 제안된 전압 제어 발진기의 위상 잡음과 주파수 조절 범위는 -127.50~-125.33 dBc/Hz @ 100 kHz와 5.744~5.852 GHz이다.

• International Journal of Aeronautical and Space Sciences
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• 제17권4호
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• pp.622-630
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• 2016

In the operation of a low earth orbit satellite, a series of antenna commands are transmitted from a ground station to the satellite within a visibility window (i.e., the time period for which an antenna of the satellite is visible from the station) and executed to control the antenna. The window is a limited resource where all data transmission is carried out. Therefore, minimizing the transmission time for the antenna commands by reducing the data size is necessary in order to provide more time for the transmission of other data. In this paper, we propose a geometric compression method based on B-spline curve fitting using dominant points in order to compactly represent the antenna commands. We transform the problem of command size reduction into a geometric problem that is relatively easier to deal with. The command data are interpreted as points in a 2D space. The geometric properties of the data distribution are considered to determine the optimal parameters for a curve approximating the data with sufficient accuracy. Experimental results demonstrate that the proposed method is superior to conventional methods currently used in practice.