• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.223-225
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• 2005

An external electrode fluorescent lamps (EEFLs) have the advantage of a long lifetime in the early stages of the study on plasma discharge, interest in the lamp continues. Studies on the operation of external electrode fluorescent lamps have focused mainly on its use of a type of high frequency (MHz). By performing high brightness using a square wave operation method with the low frequency below 100kHz, which is applied to a narrowed tube type lamp that has several mm of lamp diameter, an EEFL presented the possibility of using it as a light source for backlights. However, because an EEFL generates plasma using wall charges, which considers the impedance characteristics of glass based on the structural principle in discharge, it can be significantly affected by frequency. Thus, this study verifies the change in the characteristics of electromagnetic fields according to the change in frequency through a Maxwell's electromagnetic field simulation and examines the relationship between the change in the EEFL frequency and brightness by measuring the optical characteristics. In addition, the characteristics of the transformation of energy orbits were verified by investigating the characteristics of the wavelength according to the change in frequency through the OES.

• 전기학회논문지
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• 제56권2호
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• pp.355-360
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• 2007

The recent TFT-LCD Trend that is done large size gradually. As size of monitor great, though problem happens, it is that consumer's request which it makes monitor combined TV function. Monitor and TV are no difference externally greatly, but define difference happens as for backlight. An external electrode fluorescent lamp (EEFL) has an advantage of a long lifetime in the early stages of the study on plasma discharge, interest in the lamp continues. Researches on the operation of external electrode fluorescent lamps have focused mainly on its use of a type of high frequency (MHz). By performing high Luminance using a square wave operation method with the low frequency below 100kHz, which is applied to a narrowed tube type lamp that has several mm of lamp diameter, EEFL presented the possibility of using it as a light source for back-lights. However, because EEFL generates plasma using wall charges, which considers the impedance characteristics of glass based on the structural principle in discharge, it can be significantly affected by frequency. Thus, this study verified the change in the characteristics of electromagnetic fields according to the change in frequency through a Maxwell electromagnetic field simulation and examined the relationship between the change in the EEFL frequency and Luminance by measuring the optical characteristics.

• Advances in materials Research
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• 제5권3호
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• pp.181-192
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• 2016

In this work effect of high energy milling on the structural and electrical properties of $Ba(Fe_{1/2}Ta_{1/2})O_3$ (BFT) ceramic synthesized using standard solid-state reaction method were investigated. X-ray diffraction studies indicated that the unit cell structure for all the samples to be hexagonal (space group: P3m1). FTIR spectra also confirmed the formation of BFT without any new phase. The milled (10 h) BFT ceramic showed the formation of small grain sizes (<$2{\mu}m$) which is beneficial for dielectric applications in high density integrated devices. Besides, the milled (10 h) BFT ceramic sample exhibited superior dielectric properties (enhancement in ${\varepsilon}^{\prime}-value$ and reduction in $tg{\delta}-value$) compared to un-milled one. Impedance analysis indicated the negative temperature coefficient of resistance (NTCR) character. The correlated barrier hopping model (jump relaxation type) is found to successfully explain the mechanism of charge transport in present ceramic samples.

• 로봇학회논문지
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• 제8권1호
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• pp.8-19
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• 2013

One of the important issues for structural and electrical specifications in developing a robot is to determine lengths of links and motor specifications, which need to be appropriate to the purpose of robot. These issues become more critical for a gait rehabilitation robot, since a patient wears the robot. Prior to developing an entire gait rehabilitation robot, designing of a 1DOF assistive knee joint of the robot is considered in this paper. Human gait motions were used to determine an allowable range of knee joint that was rotated with a linear type actuator (ball-screw type) and links. The lengths of each link were determined by using an optimization process, minimizing the stroke of actuator and the total energy (kinetic and potential energy). Kinetic analysis was performed in order to determine maximum rotational speed and maximum torque of the motor for tracking gait trajectory properly. The prototype of 1 DOF assistive knee joint was built and examined with a impedance controller.

• 한국전자파학회논문지
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• 제13권3호
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• pp.301-307
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• 2002

본 논문에서는 종래 세라믹 칩 안테나의 단점인 협대역 특성을 개선하기 위해 헬리컬 구조를 갖는 적층형 세라믹 칩 안테나의 인덕턴스가 대역폭 향상에 미치는 영향을 3D 구조 시뮬레이션 결과에 의해 고찰하였다. 적층형 세라믹 칩 안테나를 고주파 구조 시뮬레이터인 HFSS에 의해 설계하였고, LTCC-MLC 공정 기술을 이용하여 유전 특성이 $\varepsilon$$_{r}$=7.8, tan $\delta$=0.0043인 유전체로 구현하였다. 또한, IMT-2000용 단말기에 적용 가능성을 보기 우하여 그 운용 주파수 (1,920~2,170 GHz)대에 설계된 안테나 제작하여, 주파수 응답 특성 및 복사 특성을 측정하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 영호남 합동 학술대회 및 춘계학술대회 논문집 센서 박막 기술교육
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• pp.74-76
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• 2006

An external electrode fluorescent lamp (EEFL) has an advantage of a long lifetime in the ear1y stages of the study on plasma discharge, interest in the lamp continues. Researches on the operation of external electrode fluorescent lamps have focused mainly on its use of a type of high frequency (MHz). By performing high brightness using a square wave operation method with the low frequency below 100kHz, which is applied to a narrowed tube type lamp that has several mm of lamp diameter, EEFL presented the possibility of using it as a light source for back-lights. However, because EEFL generates plasma using wall charges, which considers the impedance characteristics of glass based on the structural principle in discharge, it can be significant1y affected by frequency. Thus, this study verified the change in the characteristics of electromagnetic fields according to the change in frequency through a Maxwell's electromagnetic field simulation and examined the relationship between the change in the EEFL frequency and brightness by measuring the optical characteristics. In addition, the characteristics of the transformation of energy orbits were verified by investigating the characteristics of the wavelength according to the change in frequency through the OES.

• Structural Engineering and Mechanics
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• 제58권5호
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• pp.887-903
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• 2016

This study analyses the seismic response of a three-dimensional (3-D) rigid massless square foundation resting or embedded in a viscoelastic soil limited by rigid bedrock. The foundation is subjected to harmonic oblique seismic waves P, SV, SH and R. The key step is the characterization of the soil-foundation interaction by computing the impedance matrix and the input motion matrix. A 3-D frequency boundary element method (BEM) in conjunction with the thin layer method (TLM) is adapted for the seismic analysis of the foundation. The dynamic response of the rigid foundation is solved from the wave equations by taking into account the soil-foundation interaction. The solution is formulated using the frequency BEM with the Green's function obtained from the TLM. This approach has been applied to analyze the effect of soilstructure interaction on the seismic response of the foundation as a function of the kind of incident waves, the angles of incident waves, the wave's frequencies and the embedding of foundation. The parametric results show that the non-vertical incident waves, the embedment of foundation, and the wave's frequencies have important impact on the dynamic response of rigid foundations.

• Corrosion Science and Technology
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• 제7권5호
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• pp.243-251
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• 2008

Magnesium alloys become popular research topic in last decade due to its light weight and relatively high strength-to-weight ratio in the energy aspiration age. Almost all structure materials are supposed to suspend stress. Magnesium is quite sensitive to corrosive environment, and also sensitive to environmental assisted cracking. However, so far we have the limited knowledge about the environmental sensitive cracking of magnesium alloys. The corrosion fatigue (CF) test was conducted. Many factors' effects, like grain size, texture, heat treatment, loading frequency, stress ratio, strain rate, chemical composition of environment, pH value, relative humidity were investigated. The results showed that all these factors had obvious influence on the crack initiation and propagation. Especially the dependence of CF life on pH value and frequency is quite different to the other traditional structural metallic materials. In order to interpret the results, the electrochemistry tests by polarization dynamic curve and electrochemical impedance spectroscopy were conducted with and without stress. The corrosion of magnesium alloys was also studied by in-situ observation in environmental scanning electron microscopy (ESEM). The corrosion rate changed with the wetting time during the initial corrosion process. The pre-charging of hydrogen caused crack initiated at $\beta$ phase, and with the increase of wetting time the crack propagated, implying that hydrogen produced by corrosion reaction participated in the process.

• 한국음향학회지
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• 제6권1호
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• pp.39-47
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• 1987

구조 및 음의분석을 통해 피아노의 등가회로를 구성하였다. 최저음부의 기본주파수성분은 방사저항이 작아 음향출력도 작아짐을 보였고, 측정을 통해 확인하였다. 현의 강성으로 인해 피아노음의 부분음들은 기본진동수의 배수가 되지 않고 높아지는데 최저음부에서 특히 문제로 되는 이 inharmonicity를 감소시켜 저음부 음질개선을 할 수 있는 새 방안을 강구하였다. 즉 브릿지의 위치만을 조절하여 harmonicity를 감소시키는 것으로 향판중심부로 브릿지를 위치시킬수록 향판최저공진수 이하의 주파수가 낮아진다. 이는 피아노 설계시에 적용할 수 있어 실제적 음질개선방안이 될 수 있다. 특히 소형피아노의 경우에 더욱 효과가 있을 것이다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 광주전남지부
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• pp.75-78
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• 2006

An external electrode fluorescent lamps (EEFLs) have the advantage of a long lifetime in the early stages of the study on plasma discharge, interest in the lamp continues. Studies on the operation of external electrode fluorescent lamps have focused mainlyon its use of a type of high frequency (MHz). By performing high brightness using a square wave operation method with the low frequency below 100kHz, which is applied to a narrowed tube type lamp that has several mm of lamp diameter, an EEFL presented the possibility of using it as a light source for backlights. However, because an EEFL generates plasma using wall charges, which considers the impedance characteristics of glass based on the structural principle in discharge, it can be significantly affected by frequency. Thus, this study verifies the change in the characteristics of electromagnetic fields according to the change in frequency through a Maxwell's electromagnetic field simulation and examines the relationship between the change in the EEFL frequency and brightness by measuring the optical. characteristics. In addition, the characteristics of the transformation of energy orbits were verified by investigating the characteristics of the wavelength according to the change in frequency through the OES.