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직교 입력 편광에 따른 위상 천이 장주기 격자의 pH 및 온도 응답에 관한 연구
이슬이(Seul-Lee Lee),이용욱(Yong Wook Lee) 한국조명·전기설비학회 2021 조명·전기설비학회논문지 Vol.35 No.3
In this paper, we demonstrated an optical fiber sensor based on a phase-shifted long-period fiber gratin g (PS-LPFG) that could realize simultaneous measurement of surrounding pH and temperature variations. The PS-LPFG composed of a grating-free fiber region (GFFR) in the middle of two identical LPFGs was fabricated on high-birefringence fiber (HBF) with CO₂ laser pulses. In addition, a π phase shift formed by setting the length of the GFFR as half of the grating period of an LPFG allows a transmission dip to split into two attenuation bands at two different resonance wavelengths. Since HBF can preserve a linear state of polarization (SOP) if the input SOP is aligned with one of its two principal axes (fast or slow axis), a PS-LPFG inscribed on HBF (HB-PS-LPFG) can create two different transmission spectra for two orthogonal input SOPs, i.e., linear horizontal polarization (LHP) and linear vertical polarization (LVP). To investigate pH and temperature responses of the fabricated HB-PS-LPFG, the dip wavelength separation bet ween two different attenuation bands was used as a sensor indicator for an LHP or LVP input SOP. Consequently, pH- and temperature-induced wavelength variations of the two sensor indicators showed linear and independent spectral responses to both pH and temperature variations in a pH range from 3 to 11 and a temperature range from 25 to 65 °C. With these unique pH or temperature responses of the two sensor indicators, the fabricated sensor could realize simultaneous measurement of pH and temperature.
병원성 박테리아 검출용 헤테로다인 복조 기반 광섬유 바이오 센서
이슬이(Seul-Lee Lee),고영종(Youngjong Ko),김장현(Jang Hyun Kim),강현욱(Hyun Wook Kang),이용욱(Yong Wook Lee) 한국조명·전기설비학회 2020 조명·전기설비학회논문지 Vol.34 No.11
In this paper, we demonstrated an optical fiber biosensor based on heterodyne demodulation to detect five pathogenic bacteria species forming biofilms, such as Escherichia Coli, Vibrio Vulnificus, Pseudomonas Aeruginosa, Staphylococcus Aureus, and Streptococcus Iniae, with their fluorescence characteristics. The proposed sensor detects the fluorescence of the five bacteria species with the intrinsic fluorescence characteristics of amino acid tryptophan, whose excitation and emission wavelengths are 280 and 350 nm, respectively. The fabricated sensor consists of an UV light source for excitation of bacteria, a high sensitivity detector for detection of fluorescence signals emitted from the excited bacteria, and a lock-in amplifier for amplification of the detected fluorescence signals. The lock-in amplifier can remove various noise signals coupled with the desired fluorescence signals and amplify the magnitude of the desired signal through the heterodyne demodulation technique. This signal processing technique enables the detection of the weak picowatt (pW) fluorescence signals. Consequently, it is concluded that our sensor can successfully detect the intensity of the fluorescence signal emitted from five pathogenic bacteria species whose concentration lies within 10² to 10<SUP>7</SUP> CFU/ml.
편광상이 고리 기반 광섬유 다파장 필터의 입력 편광으로 제어되는 채널 간격 스위칭에 대한 연구
이슬이(Seul-Lee Lee),이용욱(Yong Wook Lee) 한국조명·전기설비학회 2020 조명·전기설비학회논문지 Vol.34 No.2
In this paper, we propose an optical fiber multiwavelength filter based on a polarization-diversified loop (PDL), whose channel spacings (CSs) can be controlled by its input state of polarization (SOP). The PDL-based filter consists of a polarization beam splitter, three half-wave plates (HWPs), a Faraday rotator (FR), and two polarization-maintaining fiber (PMF) segments with equal birefringence and different lengths. At proper orientation angle sets (θ<SUB>h1</SUB>, θ<SUB>h2</SUB>, θ<SUB>h3</SUB>) of the three HWPs, the proposed filter can have its polarization-dependent transmittance, offering the CS-switchable operation realized by switching between two orthogonal input SOPs of linear horizontal polarization (LHP) and linear vertical polarization (LVP). In particular, at a fixed input SOP, a half-period wavelength switching operation, i.e., an interleaving operation, can also be implemented by controlling only one HWP angle (θ<SUB>h1</SUB> or θ<SUB>h3</SUB>). Theoretical prediction was verified by experiments. For orthogonal input SOPs of LHP and LVP, the fabricated PDL-based filter could provide transmission spectra with CSs of ∼0.9 and ∼0.3nm or vice versa at appropriate sets of (θ<SUB>h1</SUB><SUB></SUB>, θ<SUB>h2</SUB>, θ<SUB>h3</SUB>), respectively, and each of the transmission spectra could be interleaved by adjusting only θ<SUB>h1</SUB> or θ<SUB>h3</SUB>.
Effect of Magnesium Nanoparticles on Graphite Oxide for Hydrogen Storage Behaviors
이슬이(Lee, Seul-Yi),박수진(Park, Soo-Jin) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.05
In this work, we prepared Mg nanoparticles loaded graphite oxide (Mg-G) as a function of Mg content in order to investigate hydrogen storage behaviors. The structure and morphology of the Mg-G samples were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The textural properties of the samples were evaluated using N₂/77 K adsorption isotherms. The hydrogen adsorption capacities were investigated at 298 K/10 MPa. As a result, the hydrogen adsorption capacities of the Mg-G were enhanced with increasing the Mg content. Therefore, it was found that the presence of Mg on graphite surfaces created hydrogen-favorable sites, resulting in enhancing the hydrogen adsorption capacity.
Effect of Acid Treatments on Hydrogen Storage Behaviors of Ordered Mesoporous Carbons
이슬이(Lee, Seul-Yi),박수진(Park, Soo-Jin) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
We investigated the effect of chemical acid treatments on hydrogen storage behaviors of the ordered mesoporous carbons (MCs). The surface functional groups and specific elements of the MCs were characterized with Fourier Transform Infrared (FT-IR) spectrometry and X-ray photoelectron spectroscopy (XPS). Also, the changes in the surface functional groups of the MCs were quantitatively detected by Boehm's titration method. The structural properties of the MCs were investigated using X-ray diffraction (XRD). The hydrogen adsorption capacity of the MCs was evaluated by means of adsorption isotherms at 77 K/1 bar. The formation of surface functional groups by the acidic treatments could influence on the hydrogen storage capacity of the MCs.
이슬비 ( Seul-bee Lee ),류대규 ( Dae-gyu Ryu ),모은진 ( Eun-jin Mo ),최원조 ( Won-jo Choe ),정용현 ( Yong-hyeon Jeong ),오재호 ( Jae-ho Oh ) 한국환경농학회 2019 한국환경농학회 학술대회집 Vol.2019 No.-
본 연구는 국내에 수입되고 있는 주류의 모니터링을 위하여 현행 식품공전 중 메탄올-가스크로 마토그래프법을 적용하여 시험법 검증을 실시하였다. 메탄올은 알코올류의 휘발성 액체로 맥주, 포도주 등 양조주의 발효과정 중에 소량 생성된다. 이러한 메탄올은 호흡기, 위장관, 피부 등 모든 경로로 흡수될 수 있으며 심각한 눈 손상을 일으키는 물질로 유해화학물질로 분류되어있다. 메탄올의 잔류허용기준은 맥주에서 0.5 mg/mL, 과실주에서 1.0 mg/mL 이하로 설정되어 있다. 본 시험법 검증을 위해 주류 검체는 맥주와 와인으로 선정하였고, 0.25, 0.5, 1 mg/mL 농도 수준을 적용하여 회수율 실험을 통해 본 시험법을 검증하였다. 시험 결과 회수율은 전체 91.5~103.8%의 범위로 확인되었으며, 상대표준편차는 10% 이내로 확인되었다. 직선성의 경우 상관계수(r<sup>2</sup>)가 0.995로 준수한 수준이며, 정량한계(LOQ)는 0.02 mg/mL이하로 확인되었다. 본 분석법은 국제 기준인 CODEX 가이드라인(CAC/GL 40, 2003)과 식품의약품안전평가원의 ‘식품 등 시험법 마련 표준 절차에 관한 가이드라인(2016)’을 만족하며, 주류 중 메탄올 분석에 적합한 시험법으로 판단된다.