• 센서학회지
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• 제15권4호
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• pp.263-268
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• 2006

We have demonstrated a highly sensitive temperature sensor using an etched single mode fiber with a thermally expanded core region. Large core size of thermally expanded core facilitates access to evanescent wave by the wet etching. The etched region was surrounded by a low dispersive external medium with high thermo-optic coefficient. Due to the large difference between the dispersion property of the fiber and that of the external medium, the device reveals a cut-off properties at spectral region. The cut-off wavelength was shifted by the variations of the environmental temperatures because of thermo-optic effect of the external medium. The sensitivity of the fabricated device was found to be $45nm/^{\circ}C$.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 춘계학술발표논문집 1부
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• pp.253-256
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• 2010

Since the amplitude of voiced fall off at about -20dB/decade, dynamic range is often compressed prior to spectral analysis so that details at weak, high frequencies may be visible. Preemphasizing the speech, either by differentiating the analog speech $s_a$(t) prior to A/D conversion or by differencing the discrete-time s(n)=$s_a$(nT), compensating for falloff at high frequencies. The most common form of preemphasis is y(n)=s(n)-As(n-1), where A typically lies between 0.9 and 1.0 and reflects the degree of pre-emphasis. In this paper, we proposed that A is adjusted at each time by measuring the slope of envelope in frequency domain.

• Journal of the Optical Society of Korea
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• 제7권2호
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• pp.84-88
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• 2003

A new method for temperature compensation of fiber Bragg grating (FBG) using hi-metal is proposed and experimentally demonstrated. Bi-metal bends toward the metal of low temperature expansion coefficient as the temperature increases, and this property is utilized to cancel the thermo-optic effect of the fiber. The optimum thickness of the high coefficient metal was empirically found by the trial-and-error method. The temperature sensitivities were 8.1 pm/$^{\circ}C$ and -0.018 pm/$^{\circ}C$ for the uncompensated and compensated FBGs, respectively, which indicates a reduction to a mere 0.22 % of the original sensitivity. No appreciable change in the spectral shape was observed. The packaging technique described in this paper is simple and compact, and it can be used for FBGs in WDM and DWDM communication systems that have stringent requirements on the temperature stability of the components.

• 센서학회지
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• 제30권5호
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• pp.314-319
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• 2021

In this study, biomarkers were analyzed and segmented using tunable infrared gas sensors after performing the principal component analysis. The free spectral range of the device under test (DUT) was around 30 nm and DUT-5580 yielded the highest output voltage property among the others. The biomarkers (isoprophyl alcohol, ethanol, methanol, and acetone solutions) were sequentially mixed with deionized water and their mists were carried into the gas chamber using high-purity nitrogen gas. A total of 17 different mixed gases were tested with three tunable infrared gas sensors, namely DUT-3144, DUT-5580, and DUT-8010. DUT-8010 resolved the infrared absorption spectra of whole mixed gases. Based on the principal component analysis with each DUT and their combinations, each mixed gas and the trends in increasing gas concentration could be well analyzed when the contributions of the eigenvalues of the first and second were higher than 70% and 10%, respectively, and their sum was greater than 90%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권1호
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• pp.327-346
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• 2019

The goal of hyperspectral pansharpening is to combine a hyperspectral image (HSI) with a panchromatic image (PANI) derived from the same scene to obtain a single fused image. In this paper, a new hyperspectral pansharpening approach using adaptive weighted regression and guided filter is proposed. First, the intensity information (INT) of the HSI is obtained by the adaptive weighted regression algorithm. Especially, the optimization formula is solved to obtain the closed solution to reduce the calculation amount. Then, the proposed method proposes a new way to obtain the sufficient spatial information from the PANI and INT by guided filtering. Finally, the fused HSI is obtained by adding the extracted spatial information to the interpolated HSI. Experimental results demonstrate that the proposed approach achieves better property in preserving the spectral information as well as enhancing the spatial detail compared with other excellent approaches in visual interpretation and objective fusion metrics.

• Korean Chemical Engineering Research
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• 제56권6호
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• pp.792-797
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• 2018

We have explained the synthesis of novel phenanthrene and pyrene substituted phthalocyanines (PC-PHE and PC-PYR) and fully confirmed the structures by its spectral, photo physical and elemental analysis. For these phthalocyanines we checked the UV-Visible absorbance in PGMEA and chloroform and transmittance checked in PGMEA. The transmittance results suggested that these phthalocyanines are showing more than 90% transmittance at the 450-550 nm region. These synthesized molecules are nicely soluble in almost all industrial solvents. We checked the aggregation property of these phthalocyanines in PGMEA, and the results suggested no any aggregation for these molecules in PGMEA. The thermogravimetric analysis results concluded that PC-PHE and PC-PYR had high thermal stability. All studies explain that these new phthalocyanines are more suitable for LCD green color filter application.

• Journal of the Korean Physical Society
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• 제73권10호
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• pp.1546-1549
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• 2018

We have investigated core-levels of ZnO thin films at the interface with the graphene on Cu foil using in-situ X-ray Photoelectron Spectroscopy (XPS). Spectral evolution of C 1s, Zn 2p, and O 1s are observed in real time during RF sputtering deposition. We found binding energy (BE) shifts of Zn 2p and 'Zn-O' state of O 1s depending on ZnO film thickness. Core-levels BE shifts of ZnO will be discussed on the basis of electron transfer at the interface and it may have an important role in the electronic transport property of the ZnO/graphene-based electronic device.

• Kyungpook Mathematical Journal
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• 제64권2호
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• pp.205-218
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• 2024

Let 𝒜 be a Banach algebra. An element a ∈ 𝒜 has generalized Drazin inverse if there exists b ∈ 𝒜 such that b = bab, ab = ba, a - a²b ∈ 𝒜^qnil. New additive results for the generalized Drazin inverse of an operator over a Banach space are presented. we extend the main results of a paper of Shakoor, Yang and Ali from 2013 and of Wang, Huang and Chen from 2017. Appling these results to 2×2 operator matrices we also generalize results of a paper of Deng, Cvetković-Ilić and Wei from 2010.

• 한국음향학회지
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• 제30권1호
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• pp.1-8
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• 2011

본 논문에서는 ISF 계수의 순서화 성질을 이용하여 분할구조 벡터양자화기의 단점을 보완하여 ISF 계수 양자화의 성능을 높이는 알고리듬을 제안하고, 이를 이용한 광대역 음성 부호화기용 ISF 계수 양자화기를 설계한다. 16차 이상의 광대역 코덱의 ISF 계수는 계산량과 메모리 사용을 줄이기 위해서 분할구조의 벡터 양자화기를 사용한다. 분할구조 양자화기는 ISF 계수간의 상관도를 충분히 활용하지 못하는 단점이 발생한다. 제안하는 알고리듬은 이러한 단점을 극복하기 위하여 ISF 계수의 순서화 성질을 이용한다. ISF 계수의 순서화 성질을 이용하여 각 서브벡터의 불필요한 코드북 (Codebook Redundancy)을 검색할 수 있다. 이러한 불필요한 코드북은 ISF 계수의 순서화 성질, ISF 계수 예측과정과 기존 코드북의 보간법 (Interpolation)을 통해 적응적인 확장된 코드북으로 교체되어 양자화기의 성능을 향상시킨다. 제안된 알고리듬은 기존의 분할구조 양자화기에서 사용되지 못했던 17 %가량의 불필요한 코드북 인덱스를 적응적인 확장된 코드북에 할당하여, 표준화된 코덱인 AMR-WB의 ISF 계수 양자화기에 비해서 주파수 왜곡 관점에서 약 2 bit 가량의 이득을 보는 결과를 얻었다.

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1669-1678
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• 2011

Six new binuclear copper(II) complexes have been prepared by template condensation of the dialdehydes 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-l,4,8,11-tetraazacyclotetradecane (PC-a) and 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-l,4,8,11-tetraazacyclotetradecane (PC-b) with appropriate aliphatic diamines, and copper(II) perchlorate. The structural features of the complexes have been confirmed by elemental analysis, IR, UV-vis and mass spectra etc. The electrochemical behavior of all the copper(II) complexes show two irreversible one electron reduction process. The room temperature magnetic moment studies depict the presence of an antiferromagnetic interaction in the binuclear complexes. The catechol oxidation and hydrolysis of 4-nitrophenylphosphate were carried out by using the complexes as catalyst. The antimicrobial screening data show good results. The binding of the complexes to calf thymus DNA (CT DNA) has been investigated with absorption and emission spectroscopy. The complex [$Cu_2L^{1a}$] displays significant cleavage property of circular plasmid pBR322 DNA in to linear form. Spectral, electrochemical, magnetic and catalytic studies support the distortion of the copper ion geometry that arises as the macrocyclic ring size increases.