• Applied Microscopy
• /
• 제36권spc1호
• /
• pp.63-69
• /
• 2006

By utilizing a field emission gun and a biprism installed on a transmission electron microscope (TEM), electron holography is extensively carried out to visualize the electric and magnetic fields of nanomaterials. In the electric field analysis, the distribution of electric potential in a sharp tip made of W coated with $ZrO_2$ is visualized by applying the voltage to the tip. Denser contour lines due to the electric potential are observed with an increase in the bias voltage. In the magnetic field analysis by producing the strong magnetic field with a sharp magnetic needle made of a permanent magnet, the in situ experiment is carried out to investigate the magnetization of hard magnetic materials. The results of these experiments clearly demonstrate that electron holography is a promising advanced transmission electron microscopy technique to characterize the electric and magnetic properties of nanomaterials.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1993년도 하계학술대회 논문집 B
• /
• pp.555-557
• /
• 1993

In this study PLZT was selected which has the excel lent quadratic electro-optic property and slim-loop. It was fabricated by the methods of vacuum hot-pressing and sintering. The electrode of color filter was evaporated using the interdigital type masks. Through XRD have we investigated the molecular structure composition formular. Hysteresis and transmission characteristics were measured. The transmission of RGB was envestigated. We are going to study the correlation of coercive field and the nontransmited field.

• 한국통신학회논문지
• /
• 제25권9B호
• /
• pp.1579-1587
• /
• 2000

This paper presents the properties of the RF part in the receiving system based in IMT-2000 terminal technology. It mainly discuss the RF parameter performance of the receiving system for mobile telecommunication comparable to IS-98A and J-STD-018 specifications of commercially available CDMA and PCS, and is to anticipate the processing gain of the IMT-2000 receiving system, processing gain according to data processing rate, and terminal noise figure according to processing gain, relationship between noise figures according to Eb/Nt, Ioc. It is performed by such analysis method as CDMA and PCS receiving systems. Transmission bandwidth is n$\times$1.25 MHz(n=1, 3, 6, 9, 12) which is recommended by Qualcomm and NTT, the leading company in cdma 2000. Data transmission rate of IMT-2000 is classified into three cases as in moving vehicle environment of 144Kbps, outdoor pedestrian environment of 384Kbps, and indoor office environment of 2Mbps

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
• /
• pp.272-273
• /
• 2005

전력선 통신을 위한 커플러용 자심재료의 열처리 온도증가에 따라 결정이 성장하여 인덕턴스는 증가 하였고, $550^{\circ}C$ 이상에서는 포화점을 나타내었다. 커플러는 자심재료의 투자율이 높을수록 커플러의 저주파 대역의 신호전승 특성이 우수하게 나타났지만, 주파수 증가에 따라 급격히 저하하는 불안정한 특성을 나타내었다. 그리고 절단면 사이의 Air gap 증가에 따라 10 MHz이하의 주파수 대역에서 신호전승특성이 급격히 감소하였고, 허용전류는 직선적으로 증가하였으며 Air gap이 $600{\mu}m$이상일 때 300A의 전류에서 특성을 발휘하였다.

• Tribology and Lubricants
• /
• 제21권3호
• /
• pp.142-148
• /
• 2005

In order to improve the fuel economy by design change of automatic transmission, various technologies such as increased shift stages, slip control of lock-up clutch and compact and low-weight design have been developed. And also many OEMs have developed their own ATFs as a part of these automatic transmissions. In this study, to investigate the effects of ATF characteristics on fuel economy, we got the worldwide OEM ATFs and made some reference fluids. And physical properties, frictional characteristics and fuel economy using dynamometer test for these fluids were evaluated. From the investigation, it was found that viscosities of ATFs are correlated with fuel economy in dynamometer test and reducing the viscosities made it possible to obtain fuel economy.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 II
• /
• pp.1099-1103
• /
• 2001

In room acoustics, reverberation time (RT) is the most important and general factor that represents character of room or inner space. However, RT, especially in low frequency range, can have the different value according to the measuring points and methods. This study comprehends the cause of error occurring dominantly in low frequency range when RT is measured and examines that the each error of RT measured in the cabin and reverberation chamber having different properties, influences what extent on sound transmission loss (STL)

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 II
• /
• pp.1306-1312
• /
• 2001

In this study. the acoustic power balancing method to analysis HVAC system noise is presented. The method can consider not only forward but also backward propagations of noise generated by the operation of air supply units and aerodynamical disturbance at duct elements. This can be done by estimating sound transmission and reflection properties of duct elements. and balancing acoustic powers of total HVAC system. To verify the accuracy of the presented method. numerical analysis for a HVAC system is carried out and the results are compared with those obtained by a traditional empirical method. suggested by National Environmental Balancing Bureau.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2000년도 추계학술대회논문집
• /
• pp.182-186
• /
• 2000

The porous woven hose is recently considered as an effective element of automotive intake systems. In order to predict the acoustic performance of an intake system with a porous woven hose, the information on the acoustic wall impedance is required. In this article, a measurement technique that is valid over the low frequency range and without mean flow condition is presented. The measurement is performed in a cylindrical chamber with a concentric layout of the sample and the resistance is estimated from measured reactance and transmission loss data. It is observed that the measured transmission loss for a porous woven hose with an arbitrary length agrees well with the predicted one that uses the estimated impedance for a small sample length.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2012년도 춘계학술발표회 논문집
• /
• pp.271-272
• /
• 2012

Ar 이온빔을 이용한 플라즈마 표면 처리 공정이 냉연 강판 위에 증착된 Zn-Mg 코팅 박막의 구조적 특성에 미치는 영향을 규명하기 위해 투과전자현미경(TEM, Transmission Electron Microscopy)을 이용한 미세 나노 계면 분석을 수행하였다. 냉연 강판위에 형성된 자연 산화막이 Ar 플라즈마 표면 처리에 의해서 효과적으로 제거 되는 현상을 관찰 하였다. Ar 플라즈마 표면 처리 횟수가 증가됨에 따라, Zn-Mg 박막의 입계 크기가 증가하며, 이는 플라즈마 전처리 공정으로 냉연 강판 표면이 활성화가 촉진되어 Zn-Mg 박막의 결정 성장이 원활히 이루어졌기 때문으로 판단된다.

• Journal of the Optical Society of Korea
• /
• 제12권4호
• /
• pp.314-318
• /
• 2008

We investigate the conditions of the complete tunneling of light across a composite barrier made of multiple layers involving metamaterials. It is shown that complete tunneling phenomena are related to the resonance transmission properties of local modes formed in barrier layers and that there are two distinctive kinds of local barrier modes involved in actual complete tunneling: the degenerate inner-barrier mode and the full barrier mode. Complete tunneling occurs via two successive mode couplings: from the incident plane wave to the plane wave in the transmission layer through the direct mediation of these two kinds of local barrier modes.