• 대한환경공학회지
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• 제33권8호
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• pp.598-605
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• 2011

본 연구의 주 목적은 다층 다단 다공성 시스템에 편극전하 방식을 부가하여 본 시스템의 집진특성을 실험적으로 해석하는데 있다. 본 시스템의 압력손실 및 집진효율 특성 해석을 위해 실험은 인가전압, 시스템 유입유속, 유입농도 및 stage 수 등의 실험적 변수들에 의해 수행된다. 실험결과, 기류유입 시 유입유속 $v_{in}$ = 3.11 m/s에서 단(stage) 수 변화($1{\rightarrow}5$단)에 따라 압력손실은 $18{\sim}134mmH_2O$를 나타낸다. 인가전압 0 kV 및 기류유입이 없을 때, 시스템 유입유속 $v_{in}$ = 2.58 m/s인 경우 5 stage에서 집진효율은 92.5% 인 데 비해, 동일 유속에서 플레이트 별 편극전하(alternating polarization charge-applied voltage 2.5 kV) 및 기류유입 시스템인 경우 5 stage 효율은 98.5%로 전자에 비해 6% 정도 매우 높은 효율 상승을 보인다.

• 한국광학회지
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• 제29권6호
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• pp.262-267
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• 2018

본 논문에서는 유기발광다이오드 디스플레이(OLED)의 광 효율을 향상시키기 위해 방사방지필름을 새롭게 디자인하였다. 현재 상용화되고 있는 편광판의 편광도와 투과율을 변화시켜 OLED 반사방지필름에 사용하였을 경우 정면과 측면방향의 반사특성을 계산하였다. 그 결과 편광도가 99.995%나 99.990%인 상용화된 편광판의 편광도를 99.9% 수준으로 떨어뜨릴 경우, 반사방지필름의 평균 시감반사율은 사람의 눈으로 알아차리기 힘든 약 0.1% (증가율 환산 2.5%) 상승한 반면, 투과율은 기존보다 약 1.63~3.34%(증가율 환산 4.2~8.2%) 상승하였다. 이 결과는 기존 OLED에서 저반사율을 유지하면서 광효율을 상승시킬 수 있는 광학설계 조건을 제시하였다.

• Journal of the Optical Society of Korea
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• 제15권3호
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• pp.289-292
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• 2011

Reactive mesogen (RM) is an organic liquid crystal molecule that can be self-aligned to have an optic axis of birefringence when coated over a polyimide alignment film. A free-standing optical wave-plate film consisting of RM and low-loss optical polymers was fabricated in this work, and the film was inserted across the polymer waveguide to form an integrated optical polarization converter. For convenient evaluation of the polarization converters, a waveguide polarizer and analyzer were fabricated in series. The polarization conversion efficiency was measured to be 25 dB for the wavelength range from 1520 to 1580 nm. The wave plate exhibited a temperature-dependent retardation of $4.5^{\circ}$ for a temperature change from 25 to $100^{\circ}C$.

• Current Optics and Photonics
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• 제8권4호
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• pp.416-420
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• 2024

A high-power Yb:YAG thin-disc laser with radial or azimuthal polarization incorporating an intracavity S-waveplate is reported. Depending on the rotational angle of the S-waveplate placed in the cavity, a Yb:YAG thin-disc laser yields 10.8 W and 10.2 W of continuous-wave outputs with radial and azimuthal polarization for an incident pump power of 131 W, corresponding to slope efficiencies of 22.9% and 23.7%, respectively. The output characteristics for each polarization state were investigated in detail by analyzing the insertion loss and the mode overlap efficiency due to the S-waveplate. Further prospects for power scaling will be discussed.

• Corrosion Science and Technology
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• 제2권5호
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• pp.233-237
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• 2003

Pickling inhibitors can be used to form an adsorbed layer on the metal surface to hinder the discharge of H^+$ and dissolution of metal ions. Nitrogen-containing inhibitors were selected as corrosion inhibitors for mild steel (MS) in pickling acid process. In this study, the addition of inhibitor, the pickling temperatures and the pickling times were the parameters to investigate the effects on the inhibition efficiency (IE) for MS by using weight loss measurement. Preliminary results show that the IE increased with the increase in pickling time from 10 minutes to 60 minutes, and the IE also increased with the increase in temperature at room temperature and $40^{\circ}C$. At the higher temperature. the IE values are higher and almost independent with the pickling time. Furthermore, the potentiodynamic polarization, open circuit corrosion potential-time and corrosion current-time studies show that nitorgen-containing inhibitor behaves predominantly as cathodic polarization. The roughness test and SEM investigation are also studied in this paper.

• 대한기계학회논문집B
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• 제21권11호
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• pp.1509-1517
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• 1997

Charged and uncharged particle motions and collection characteristics around a bipolar charged rectangular shape electret fiber are studied numerically. Particle inertia, fluid drag, Coulomb force and polarization force are considered to predict the particle motion around the electret fiber. The effects of particle sizes, flow velocities, number of charges and polarities are also systematically investigated. For small size particles, the single fiber collection efficiency is greatly dependent on the charge polarity and the number of charges on a particle. However, particles larger than 5.mu.m do not show charging effect on collection efficiencies in the flow velocity ranges from 1.5 cm/s to 150 cm/s when the maximum charges are within +5 to -10. The results show that a strong electric field gradient at the corner of the bipolar charged fiber plays a very important role on collecting particles regardless of its charge polarity because of the polarization force. It also shows that the most penetrating particle size for a single electret fiber decreases as the flow velocity increases and the number of charges of a particle decreases.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.821-824
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• 1999

In this article, as a way of pursuing high spectral efficiency and flexible cell planning, co-channel dual-polarization techniques are suggested for B-WLL applications. It provides a double down stream capacity compared with conventional scheme and also makes some flexibility in cell planning. In order to implement co-channel B-WLL system, some frequency plans, interference cancellation methods, and system block diagrams are presented here.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.268-269
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• 2000

We demonstrate a polarization insensitive waveguide filter using quantum well intermixing(QWI). The bandgap of epitaxial layer is modified from 1.55${\mu}{\textrm}{m}$ to 1.40${\mu}{\textrm}{m}$ using QWI and a Bragg grating filter is demonstrated using electron beam lithography technology. The fabricated waveguide filter has a 70% reflection efficiency and a 1.46nm filter bandwidth. Furthermore polarization insensitive transmission characteristics are observed. The device can be applied to photonic integrated circuits(PIC).

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.980-981
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• 2007

Liquid crystal (LC) devices can be operated as amplitude modulators and phase modulators. They usually require two polarizers; therefore the optical efficiency is limited. We introduce two general principles of polarization-free liquid crystal devices and also show several LC devices by applying the principles.

• Bulletin of the Korean Chemical Society
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• 제16권5호
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• pp.454-458
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• 1995

Inhibiting action of semicarbazide, thiosemicarbazide, sym. diphenylcarbazide towards corrosion of zinc in hydrochloric acid has been investigated. The rate of corrosion depends on the nature of the inhibitor and its concentration. The values of inhibition efficiency from, weight loss, thermometric measurements are in good agreement with those obtained from polarization studies. From the polarization studies, the inhibitors used act as mixed absorption type inhibitors, increased adsorption resulting from an increase in the electron density at the reactive C=S and C=O groups and N-atoms. The thermodynamic parameters of adsorption obtained using Bockris-Swinkels adsorption isotherm reveal a strong interaction of these carbazides on zinc surface.