• 한국광학회지
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• 제9권2호
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• pp.104-110
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• 1998

Cu 도핑된(0.04 wt.%) 광굴절 (K/sub 0.5/Na/sub 0.5/)/sub 0.2/(Sr/sub 0.61/Ba/sub 0.39/)/sub 0.9/Nb/sub 2/O/sub 6/ 결정에서 두 빔간의 에너지 교환특성을 632.8 nm He-Ne 레이저 파장에서 해석하고 측정하였다. 또한 신호빔 혹은 기준빔이 고주파에서 진폭 변조될 때 광유기된 굴절율 부피 격자의 코히어런트한 2광파 결합 특성을 해석하고 실험하였으며, 코히어런트 광통신 시스템 및 광신호처리 분야에서 동적 광굴절 결합기및 펄스 shaping 소자로 활용하기 위한 예비 실험 결과를 제시했다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권12호
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• pp.6190-6213
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• 2019

For small-scale vector data, restrictions on watermark scheme capacity and robustness limit the use of copyright protection. A watermarking scheme based on robust geometric features and capacity maximization strategy that simultaneously improves capacity and robustness is presented in this paper. The distance ratio and angle of adjacent vertices are chosen as the watermark domain due to their resistance to vertex and geometric attacks. Regarding watermark embedding and extraction, a capacity-improved strategy based on quantization index modulation, which divides more intervals to carry sufficient watermark bits, is proposed. By considering the error tolerance of the vector map and the numerical accuracy, the optimization of the capacity-improved strategy is studied to maximize the embedded watermark bits for each vertex. The experimental results demonstrated that the map distortion caused by watermarks is small and much lower than the map tolerance. Additionally, the proposed scheme can embed a copyright image of 1024 bits into vector data of 150 vertices, which reaches capacity at approximately 14 bits/vertex, and shows prominent robustness against vertex and geometric attacks for small-scale vector data.

• Journal of Information Display
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• 제5권1호
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• pp.22-27
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• 2004

Photopolymers are quite promising candidates for holographic data storage and diffusers because of their high sensitivity and high refractive index modulation. New photopolymers were prepared using the cellulose ester binder bearing different kinds of monomer. The holographic gratings were elaborated successfully in these photopolymer samples by conventional optical interference method. We investigated the dynamic behavior of the diffraction efficiency and the effect of the functionality of the monomer doped into the polymer binder. Triacrylate monomer doped photopolymer showed the highest diffraction efficiency of around 80-90 %, even under low intensity of writing beam (I=2 mW/$cm^2$). We inscribed the gratings of the glass diffuser on the surface of the photopolymer and investigated their diffusion properties.

• Macromolecular Research
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• 제13권6호
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• pp.477-482
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• 2005

Photopolymers are attractive materials for holographic 3-D data storage because of their high photosensitivity and large refractive index modulation. We synthesized the six-armed dendrimer for fabricating the new photopolymer. It was prepared using the initiating mixture of hexaarylbiimidazole (HABI), mercapto-benzoxazole (MOBZ), and 2,6-bis(4-diethylaminobenzylidene)cyclopentanone (DEAW), which is sensitive to 514 nm wavelength. The holographic gratings were fabricated successfully in these photopolymer samples by conventional optical interference method. We investigated the effect of dendrimer, either as a binder or as a plasticizer in the cellulose acetate butyrate (CAB), on the diffraction behavior. The addition of only 1 wt$\%$ of dendrimer-I into the CAB significantly increased the diffraction efficiency. The sample doped with dendrimer showed around 80-83$\%$ of the diffraction efficiency.

• 대한기관식도과학회:학술대회논문집
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• 대한기관식도과학회 1979년도 제13차 학술대회 연제순서 및 초록
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• pp.8.3-8
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• 1979

음의 생성은 성문하의 기류가 성대에서 조절되고 성대상부의 Vocal tract에서 modulation되어 생성되므로 후두에 이상이 생기면 발성시 후두를 통과하는 기류에 변화가 오게된다. 타국에서는 Dohne(1944)과 Arnold(1955, 1958)등 여러학자들이 후두질환에 따른 공기역학적 변화를 측정하여 후두질환의 진단에 기여한 바 크다. 본 저자들은 후두질환에 따른 공기역학적 측정에 앞서 이에 대한 정상역치를 측정하여 그 기준치로 하고자 21∼30세의 정상인 남녀 각각 20명을 대상으로 Collins회사제 Respirometer를 이용하여 평균 기류유출률, 최대 밭성량, 최대발성시간 및 발성속력치 등을 측정하였기에 제 1보로서 보고하는 바이다.

• 혜화의학회지
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• 제17권2호
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• pp.117-135
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• 2008

In order to investigate the efficacy of a combination of JBB as topical and HTGMB as internal treatment method, changes in various immune related factors and histological changes in NC/Nga induced animal model was studied. Combined treatment of topical JBB and internal HTGMB significantly reduced the atopic dermatitis clinical index, the number of immune cells such as CD19+, CCR3+, B220+/IgE+, and Gr-1+/CD11b+ in DLN and dorsal skin, compared to the control group. Otherwise increased CD3+, CD4+/CD25+, CD8+ and CD4+ cells in the DLN. And also combined treatment of topical JBB and internal HTGMB suppressed the lymphocytes and mast cells from infiltrating into the skin tissues when stained with H&E and toluidine blue. Based on the results above, it is strongly suggested that the combined treatment of topical JBB and internal HTGMB significantly induced anti-allergic activities through immune modulation. The findings can be applied to developing a more sustainable treatment for atopic dermatitis and be helpful in practicing combined treatments in clinical treatments in the future.

• Archives of Pharmacal Research
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• 제28권11호
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• pp.1293-1301
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• 2005

Flavonoids, a group of low molecular weight phenylbenzopyrones, have various pharmacological properties including antioxidant, anticancer, bactericidal, and anti-inflammatory. We carried out anti-herpetic assays on 18 flavonoids in five classes and a virus-induced cytopathic effect (CPE) inhibitory assay, plaque reduction assay, and yield reduction assay were performed. When flavonoids were applied at various concentrations to Vero cells infected by HSV-1 and 2, most of the f1avonoids showed inhibitory effects on virus-induced CPE. Among the flavonoids, EC, ECG (flavanols), genistein (isoflavone), naringenin (flavanone), and quercetin (flavonol) showed a high level of CPE inhibitory activity. The antiviral activity of flavonoids were also examined by a plaque reduction assay. EC, ECG, galangin, and kaempferol showed a strong antiviral activity, and catechin, EGC, EGCG, naringenin, chrysin, baicalin, fisetin, myricetin, quercetin, and genistein showed moderate inhibitory effects against HSV-1. In these experiments, flavanols and flavonols appeared to be more active than flavones. Furthermore, treatment of Vero cells with ECG and galangin (which previously showed strong antiviral activities) before virus adsorption led to a slight enhancement of inhibition as determined by a yield reduction assay, indicating that an intracellular effect may also be involved.

• 제어로봇시스템학회논문지
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• 제22권6호
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• pp.453-462
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• 2016

This paper proposes a torque control method for surface mounted permanent magnetic synchronous motor (PMSM) driven by a 2-level voltage source driven inverter, which has fast torque response and small torque ripple. The proposed torque control method follows the finite control set model predictive control (FCS-MPC) strategy. A reference state is derived at each time step for the given time varying torque reference and the cost index is defined so that the tracking error for this reference state should be penalized. The choice of an optimal output voltage vector is made first from the 6 possible active voltage vectors of the 2-level voltage source inverter. Then a modulation factor for the chosen optimal voltage vector is obtained so that the torque ripple can be reduced further. It is shown that the proposed FCS-MPC control method yields fast torque tracking response and small torque ripple through simulation and experiments.

• 전력전자학회논문지
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• 제3권1호
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• pp.8-14
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• 1998

본 논문에서는 실시간 구현이 가능한 최적 PWM 방식을 제안한다. 제안된 방식은 전압의 적분치를 지속으로 정의하고, 기준지속과 실제 출력자속간의 지속오차에 대한 제곱의 적분치를 성능함수로 정의하여 이를 최소화 하도록 펄스의 폭과 위치를 실시간으로 계산한다. 고조파분석을 통하여 natural PWM 및 직접 PWM 방식과 고조파 성분을 비교하였으며 80C196KC 마이크로콘트롤러를 사용한 유도전동기 구동에 적용하여 제안된 기법의 유용성을 보였다. 제안된 방식을 스위칭 주파수가 제한되는 대용량 전력변환 장치에 유용하게 적용될 수 있다.

• ETRI Journal
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• 제37권3호
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• pp.595-605
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• 2015

This paper proposes a robust, imperceptible block-based digital video watermarking algorithm that makes use of the Speeded Up Robust Feature (SURF) technique. The SURF technique is used to extract the most important features of a video. A discrete multiwavelet transform (DMWT) domain in conjunction with a discrete cosine transform is used for embedding a watermark into feature blocks. The watermark used is a binary image. The proposed algorithm is further improved for robustness by an error-correction code to protect the watermark against bit errors. The same watermark is embedded temporally for every set of frames of an input video to improve the decoded watermark correlation. Extensive experimental results demonstrate that the proposed DMWT domain video watermarking using SURF features is robust against common image processing attacks, motion JPEG2000 compression, frame averaging, and frame swapping attacks. The quality of a watermarked video under the proposed algorithm is high, demonstrating the imperceptibility of an embedded watermark.