• 조명전기설비학회논문지
• /
• 제27권2호
• /
• pp.1-6
• /
• 2013

In this paper, we implemented a polarimetric strain sensor using a Sagnac birefringence interferometer composed of a polarization-maintaining photonic crystal fiber (PM-PCF). By changing the length of the PM-PCF employed as the sensor head of the proposed sensor, the length dependence of the strain sensitivity was investigated. With respect to 5.0-, 7.5-, and 10.0-cm-long PM-PCFs, strain measurements were done in a measurement range of $0{\sim}6m{\varepsilon}$, and strain sensitivities of ~2.04, ~1.92, and ${\sim}1.73pm/{\mu}{\varepsilon}$ were obtained, respectively. If an ideal PM-PCF with no length dependence of a modal birefringence is used for the proposed sensor, the strain sensitivity is independent of the length of the sensor head (PM-PCF). In the practical PM-PCF used in experiments, however, a shorter PM-PCF has a higher length dependence of the modal birefringence due to its imperfectness and nonuniformity of the internal structure, resulting in a higher length dependence of the strain sensitivity.

• 한국재료학회지
• /
• 제15권2호
• /
• pp.121-125
• /
• 2005

Magnetoelectric (ME) effects for lanthanum modified $BiFeO_3-PbTiO_3\;(BE-_xPT)$ solid solutions have been investigated. The value of magnetoelectric polarization coefficient, up is 10 times greater than that of $Cr_2O_3$. The results also show that up is due to a linear coupling between polarization and magnetization, and that up is independent of do magnetic bias and ac magnetic field. The ME effect is believed to be significantly enhanced due to breaking of the cycloidal spin state of a long-period spiral spin structure, via randomly distributed charged imperfections.

• 한국세라믹학회지
• /
• 제44권6호
• /
• pp.308-312
• /
• 2007

Ferroelectric, magnetic, and magnetoelectric effects for lanthanum modified $BiFeO_3-PbTiO_3$ ceramics have been investigated. The data show that magnetoelectric polarization coefficient, ${\alpha}_p$ is due to a linear coupling between polarization and magnetization, and that ${\alpha}_p$ is independent of dc magnetic bias and ac magnetic field. The values of ${\alpha}_p$ and magnetic induced susceptibility for lanthanum modified $BiFeO_3-PbTiO_3$ ceramics are much larger than those of single $BiFeO_3$ crystal. We believe that the magnetoelectric effect is significantly enhanced by breaking of the cycloidal spin state of a long-period spiral spin structure due to randomly distributed charged imperfections.

• 한국광학회지
• /
• 제14권2호
• /
• pp.116-121
• /
• 2003

매개하향변환과정에서 발생한 광자쌍과 Hong-Ou-Mandel 간섭계를 이용한 4차 간섭실험에서 비고전적인 간섭효과를 관측하였다. 편광방향이 서로 수직인 두 광의 4차 간섭에서 간섭무늬의 선명도가 고전적인 한계인 50%를 넘는 최대 85%의 간섭무늬를 관측하였다. 또한 두 빔의 세기 비율이 증가할수록 간섭무늬의 선명도가 감소하는 고전적인 간섭현상과 달리 두 광의 세기 비율이 1:10인 경우에도 83%의 선명도를 갖는 간섭효과를 측정하였다.

• 조명전기설비학회논문지
• /
• 제23권10호
• /
• pp.7-13
• /
• 2009

본 논문에서는 편광 빔 분배기와 광섬유 결합기를 이용하여, 입력 편광에 무관한 반사형 및 투과형 인터리빙 필터로 동작할 수 있는 다파장 스위칭 가능한 광섬유 인터리빙 필터를 제안한다. 제안된 필터는 50:50 광섬유 결합기, 편광 유지 광섬유, 그리고 2개의 1/4 파장판으로 구성되는 Sagnac 복굴절 필터의 출력 양단을 편광 빔 분배기의 출력 양단과 연결함으로써 구성하였다. 제작된 필터는 반사형 및 투과형 모두 0.8[nm]의 채널 간격을 가지는 것으로 측정되었으며, 필터 내부의 1/4 파장판의 방위각을 조절함으로써 0.4[nm]의 스위칭 변위를 갖는 인터리빙 동작이 가능하였다. 또한, 필터의 채널 고립도는 반사형과 투과형에서 각각 ~3[dB]와 > 18[dB]로 측정되었다.

• 지구물리와물리탐사
• /
• 제25권3호
• /
• pp.120-128
• /
• 2022

국내에는 17,000여개의 저수지가 존재하며, 이중 85% 이상은 50년 이상 경과된 노후 저수지이다. 이들 저수지는 내부침식 및 세굴 현상에 의한 누수와, 그에 따른 붕괴의 위험에 직면하고 있다. 이들 저수지 및 댐의 붕괴를 방지하기 위해서는 누수를 조기에 파악하고 대비하는 것이 중요하다. 전기비저항 탐사는 저수지의 전반적인 상태 파악은 물론 누수의 발달여부 탐지가 가능한 비파괴, 실시간, 현장조사법이다. 이러한 장점 때문에 전기비저항 탐사법은 저수지 안전진단에 널리 사용되고 있다. 그러나 전기비저항 탐사법은 저수지의 안전도에 대한 정량적인 지수를 제공하지 못해 공식적으로 저수지 정밀 안전진단의 상태평가 항목에 포함되어 있지 못하다. 이 연구에서는 전기비저항 탐사와 유도분극 탐사를 통하여 계산된 수분함량에 근거한 정량적 누수지수 산출법을 제시하였다. 특히 일회성 탐사와 모니터링에 의한 정량적 누수지수 산출법을 개발하여 전기비저항 탐사와 유도분극 탐사가 향후 저수지 정밀 안전진단의 상태평가 항목으로 진입할 수 있는 이론적 기반을 제시하였다.

• The Korean Journal of Ceramics
• /
• 제6권2호
• /
• pp.150-154
• /
• 2000

Mobilities of electrons ($\mu_p$) and holes ($\mu_p$) in 2, 5, and 10 mol% $TiO_2$-doped yttria stabilized zirconia (TD-YSZ) have been estimated by a non-steady state gas permeation method using models proposed by Weppner and Maruyama. Values of $\mu_n$ and $\mu_p$ were found to be closed to those in non-doped YSZ reported earlier. The concentration of electrons and holes were calculated from $\mu_n$ and $\mu_p$ values and the partial conductivities of electrons and holes measured by a dc-polarization method. The concentration of electrons at unit oxygen partial pressure increased with increasing $TiO_2$concentration, while the hole concentration was almost independent of $TiO_2$concentration.

• ETRI Journal
• /
• 제25권1호
• /
• pp.41-48
• /
• 2003

This paper presents a theoretical investigation of power reflection and transmission coefficients for a meander-line polarizer placed periodically on a chiral slab. It is assumed that a linearly polarized transverse magnetic wave is incident on a chiral slab from the air region. In the analysis, we derive the electric and magnetic fields in the modal form in the air and chiral regions. We obtain power reflection and transmission coefficients in a straightforward manner after matching the tangential components of the electric and magnetic fields at the boundaries. We present numerical results for the power reflection and transmission coefficients versus frequency and incident angle for different values of the chirality admittance. A meander-line polarizer placed on a dielectric slab can convert a linearly polarized wave to a circularly polarized wave. The design parameters for a meander-line polarizer are the dimensions of the meander-line and the values of the dielectric slab. Replacing a dielectric slab with a chiral slab introduces a new independent parameter which controls the wave polarization.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 1997년도 특별강연 및 춘계학술발표 개요집
• /
• pp.35-38
• /
• 1997

In order to investigate quantitative behavior of galvanic corrosion in the weld joint between stainless steel and carbon steel, electrochemical polarization experiments are performed for various pH, water temperature with boric acid concentration 4000ppm. The corrosion rate of stainless steel was almost independent of the variation of pH. The significant corrosion rates of carbon steel and the weld joint of carbon-carbon steel were observed at pH 4. The corrosion rates in the weld joint of the carbon-stainless steel were observed depending on the variation of pH level.

• ETRI Journal
• /
• 제34권1호
• /
• pp.126-129
• /
• 2012

An ultra-thin hexagonal microwave metamaterial absorber is described. It can absorb any polarized transverse electromagnetic wave because of its hexagonal shape. In spite of its very thin structure, almost $0.028{\lambda}g$, the absorber achieved 99% absorptivity at 11.35 GHz in experimental results because of the increased coupling losses, showing good agreement with simulation results. In addition, this high absorbance is unchanged for any polarized waves with the same frequency.