• Applied Microscopy
• /
• 제48권4호
• /
• pp.132-133
• /
• 2018

One of the most important factors determining the properties of a material is its grain size. However, unclear grain boundaries in the image hinder an accurate measurement of grain size. We demonstrate that grain boundaries existing in the images obtained by scanning transmission electron microscopy (STEM) can be clearly distinguished by applying a Sobel filter to a tilting series of STEM images of a hydrogenation-disproportionation-desorption-recombination processed Nd2Fe14B magnet sample.

• 한국컴퓨터정보학회:학술대회논문집
• /
• 한국컴퓨터정보학회 2019년도 제60차 하계학술대회논문집 27권2호
• /
• pp.341-342
• /
• 2019

송전선로에 널리 사용되고 있는 강심알루미늄연선(Aluminum Conductors Steel Reinforced, ACSR)은 스페이서와 같은 접속 부위에서 열화가 상당히 빠르게 진행된다. 그런데 현재와 같은 내용연한을 획일적으로 적용할 수 없기 때문에 설치된 송전선로의 주위 환경, 사용되는 부하 조건 등을 고려하여 합리적으로 송전선로를 운용하는 것이 필수적이므로 본 논문에서는 송전선로의 열화에 따른 특성 분석을 위한 연구를 수행하였다.

• Journal of Electrical Engineering and Technology
• /
• 제11권6호
• /
• pp.1735-1743
• /
• 2016

Insulation of valve-side windings in converter transformer withstands pulsating voltages, which will produce more serious insulation problems. In this paper, the electric breakdown experiments of oil-paper insulation specimens were executed at pulsating voltages and different temperatures. Experiment and analysis results showed that the breakdown voltage decreased with increasing temperature under pulsating voltage. The influence of temperature proves to be more significant once the temperature exceeds a limitation threshold. A fitting formula between breakdown voltage and the temperature was reported. Finally, in order to clearly understand the breakdown properties under pulsating voltage, the electric field distribution and space charge behavior under pulsating voltage at different temperature were discussed.

• 한국광학회지
• /
• 제13권1호
• /
• pp.27-31
• /
• 2002

본 논문에서는 광자 크리스탈로 구성된 1$\times$4 광 분배기를 설계하여 특성을 Finite-Difference Time-Domain 방법을 사용하여 고찰하였다. Simulation한 결과 bend에서의 4가지 광자 크리스탈 배열 구조와 입사파의 주파수에 따라 투과 특성이 변하는 것을 관찰하였다. 투과 특성이 가장 좋은 bend구조로 1$\times$4광 분배기를 설계하고 특정 주파수를 입사시킨 결과, 입사파의 파워가 4개로 균등히 나누어 짐과 전체 전송 효율이 약 93%임을 관찰하였다.

• 소음진동
• /
• 제6권5호
• /
• pp.635-644
• /
• 1996

In this paper, Allard's modelling method which employs the method of acoustic transfer matrix(ATM) is applied to yield more precise results in the analysis of porous sound absorbing material. The method of ATM, based on Biot's theory, is known to play an important role in the estimation of the sound absorption when a sound projects onto the material. In the case of a single layered porous sound absorbing material, the surface impedance and the absorption coefficient by using the method of ATM are estimated. With the variation of the material properties, sound absorption characteristics and analyzed. Transmission Loss in a combination of the porous sound absorbing material with a thin plate is predicted.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.114-114
• /
• 2010

산불에 노출되는 경우 열충격으로 작용하는 패턴과 특성을 검토하여 가속열화시험에 반영하는 것이 필요하다. 본 연구에서는 산불환경을 모의하여 복합열화시험을 실시하기위해 복합가속열화 챔버를 구축하였다. 온도는 주로 $200^{\circ}C$에서 최대 $1000^{\circ}C$까지 변화를 주면서 예비시험과 본시험 실하였다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.461-461
• /
• 2008

According to previous report, aged sleeves for old transmission lines have various defect such as biased installation or corrosion of steel sleeve. These defects occupied almost 50 percent of investigated aged sleeves. The defects have been limited power capacity of transmission line. And it can cause serious problems such as rapid increasing of sag or falling out of overhead conductor from sleeve. This paper study on thermal behavior of sleeve with various defect model. The detailed results were presented in the text.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.229-230
• /
• 2008

We have studied the structural and optical properties of ZnO thin film deposited on glass by RF magnetron sputtering as functions of working pressures. The grain sizes were decreased as the working pressures were increased. The average optical transmissions over all exceeded 80% for ZnO films deposited in 20, 25 and 300m torr working pressures. And the transmission spectra patterns were almost same. While the transmission spectra pattern of ZnO film deposited in 35nm torr was different with other spectra patterns obtained in 20, 25 and 30nm torr working pressures.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 제39회 하계학술대회
• /
• pp.1209-1210
• /
• 2008

According to previous report, aged sleeves for old transmission lines have variable defects such as biased installed case or corrosion of steel sleeve. Biased installed sleeve occupied 20 percent among the investigated aged sleeves. This defect must cause local heating of splice connector and limit power transmission capacity. It even inspire falling out of overhead conductor from sleeves. This paper studies thermal properties and tension for ACSR conductor in case of biased installed sleeve model. The detailed results were presented in the text.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
• /
• pp.891-893
• /
• 1999

Invar alloys have characteristics with very low thermal expansion coefficient and low tensile strength. The mechanical properties of invar alloy have to being improved to apply for structural materials, especially for core of transmission line in electrical field. It is necessary low thermal expansion and high strength core material to transmit increased current capacity. In this paper, we investigated effect of Mo addition affected to thermal and mechanical properties and microstructure in Fe-Ni-Co ternary system.