• Title/Summary/Keyword: Optical properties

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Discovering the Knowledge Structure of Graphene Technology by Text Mining National R&D Projects and Newspapers (국가R&D과제와 신문에서 텍스트마이닝을 통한 그래핀 기술의 지식구조 탐색)

  • Lee, Ji-Yeon;Na, Hye-In;Lee, Byeong-Hee;Kim, Tae-Hyun
    • The Journal of the Korea Contents Association
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    • v.21 no.2
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    • pp.85-99
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    • 2021
  • Graphene, called the "dream material" is drawing attention as a groundbreaking new material that will lead the era of the 4th Industrial Revolution. Graphene has high strength, excellent electrical and thermal conductivity, excellent optical permeability, and excellent gas barrier properties. In this paper, as the South Korean government recently announced Green New Deal and Digital New Deal policy, we analyze graphene technology, which is also attracting attention for its application to Corona 19 biosensor, to understand its national R&D trend and knowledge structure, and to explore the possibility of its application. Firstly, 4,054 cases of national R&D project information for the last 10 years are collected from the National Science & Technology Information Service(NTIS) to analyze the trend of graphene-related R&D. Besides, projects classified as green technology are analyzed concerning the government's Green New Deal policy. Secondly, text mining analysis is conducted by collecting 500 recent graphene-related articles from e-newspapers. According to the analysis, the field with the largest number of projects was found to be high-efficiency secondary battery technology, and the proportion of total research funds was also the highest. It is expected that South Korea will lead the development of graphene technology in the future to become a world leader in diverse industries including electric vehicles, cellular phone batteries, next-generation semiconductors, 5G, and biosensors.

Green Algae Detection in the Middle·Downstream of Nakdong River Using High-Resolution Satellite Data (고해상도 위성영상을 활용한 낙동강 녹조탐지기법 비교 및 분석)

  • Byeon, Yugyeong;Seo, Minji;Jin, Donghyun;Jung, Daeseong;Woo, Jongho;Jeon, Uujin;Han, Kyung-soo
    • Korean Journal of Remote Sensing
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    • v.37 no.3
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    • pp.493-502
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    • 2021
  • Recently, because of changes in temperature and rising water temperatures due to increased pollution sources, many algae have been produced in the water system. Therefore, there has been a lot of research using satellite images for the generation and monitoring of green algae. However, in prior studies, it is difficult to consider the optical properties of the local water system by using only a single index, and by using medium and low-resolution satellite images to conduct large-scale algae detection, there is a problem of accuracy in narrow, broad rivers. Therefore, in this work, we utilize high-resolution images of Sentinel-2 satellites to perform green algae detection on a single index (NDVI, SEI, FGAI) and development index (NDVI & SEI, FGAI & SEI) that mixes single indices. In this study, POD, FAR, and PC values were utilized to evaluate the accuracy of green algae detection algorithms, and the FGAI & SEI index showed the highest accuracy with 98.29% overall accuracy PC.

Korean Red Ginseng aqueous extract improves markers of mucociliary clearance by stimulating chloride secretion

  • Cho, Do-Yeon;Skinner, Daniel;Zhang, Shaoyan;Lazrak, Ahmed;Lim, Dong Jin;Weeks, Christopher G.;Banks, Catherine G.;Han, Chang Kyun;Kim, Si-Kwan;Tearney, Guillermo J.;Matalon, Sadis;Rowe, Steven M.;Woodworth, Bradford A.
    • Journal of Ginseng Research
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    • v.45 no.1
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    • pp.66-74
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    • 2021
  • Background: Abnormal chloride (Cl-) transport has a detrimental impact on mucociliary clearance in both cystic fibrosis (CF) and non-CF chronic rhinosinusitis. Ginseng is a medicinal plant noted to have anti-inflammatory and antimicrobial properties. The present study aims to assess the capability of red ginseng aqueous extract (RGAE) to promote transepithelial Cl- secretion in nasal epithelium. Methods: Primary murine nasal septal epithelial (MNSE) [wild-type (WT) and transgenic CFTR-/-], fisher-rat-thyroid (FRT) cells expressing human WT CFTR, and TMEM16A-expressing human embryonic kidney cultures were utilized for the present experiments. Ciliary beat frequency (CBF) and airway surface liquid (ASL) depth measurements were performed using micro-optical coherence tomography (μOCT). Mechanisms underlying transepithelial Cl- transport were determined using pharmacologic manipulation in Ussing chambers and whole-cell patch clamp analysis. Results: RGAE (at 30㎍/mL of ginsenosides) significantly increased Cl- transport [measured as change in short-circuit current (ΔISC = ㎂/㎠)] when compared with control in WT and CFTR-/- MNSE (WT vs control = 49.8±2.6 vs 0.1+/-0.2, CFTR-/- = 33.5±1.5 vs 0.2±0.3, p < 0.0001). In FRT cells, the CFTR-mediated ΔISC attributed to RGAE was small (6.8 ± 2.5 vs control, 0.03 ± 0.01, p < 0.05). In patch clamp, TMEM16A-mediated currents were markedly improved with co-administration of RGAE and uridine 5-triphosphate (8406.3 +/- 807.7 pA) over uridine 5-triphosphate (3524.1 +/- 292.4 pA) or RGAE alone (465.2 +/- 90.7 pA) (p < 0.0001). ASL and CBF were significantly greater with RGAE (6.2+/-0.3 ㎛ vs control, 3.9+/-0.09 ㎛; 10.4+/-0.3 Hz vs control, 7.3 ± 0.2 Hz; p < 0.0001) in MNSE. Conclusion: RGAE augments ASL depth and CBF by stimulating Cl- secretion through CaCC, which suggests therapeutic potential in both CF and non-CF chronic rhinosinusitis.

Temperature Dependent Optical Performance of the NaSr(PO3)3:Eu2+ Blue Phosphors (NaSr(PO3)3:Eu2+ 청색 형광체의 온도 의존적 형광 특성)

  • Yoon, Chang yong;Lee, Sang ho
    • Journal of the Korean Society of Radiology
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    • v.15 no.3
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    • pp.391-399
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    • 2021
  • Eu2+ doped polyphosphate NaSr(PO3)3 blue-emitting phosphors were synthesized by the conventional solid state method in a reductive atmosphere. The phase formation of NaSr(PO3)3 phosphors were characterized by using the X-ray powder diffraction (XRD) measurement. The photoluminescence emission and excitation spectra of the NaSr(PO3)3:Eu2+ phosphor, and decay curves were measured. Under the near-UV excitation, the phosphor exhibits a band emission around 420 nm assigned to the 4f65d→f7(8S7/2) transition of Eu2+. The temperature dependent emission spectra and decay curves were measured to elevate the thermal properties of the Eu2+ doped phosphors. The as-prepared NaSr(PO3)3:Eu2+ phosphors show a strong temperature dependent performance, which can serve as a promising temperature sensor.

Polymer Eyeglass Lens with Ultraviolet & High-Energy Visible Light Blocking Function for Eye Health (자외선 및 고에너지 가시광 차단 기능을 갖는 눈 건강을 위한 폴리머 안경렌즈)

  • Kim, Ki-Chul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.12
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    • pp.10-15
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    • 2020
  • Ultraviolet rays, which have wavelengths smaller than 400 nm, are very harmful to the eyes. Recently, high-energy visible light was also revealed to be harmful to retinal cells. Therefore, polymer eyeglass lenses that can block UV and high-energy visible light are needed for eye health. In this study, high-refractive-index polymer eyeglass lens, n=1.67, were manufactured using the injection-mold method with the m-xylene diisocyanate monomer, 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol monomer, benzotriazole UV absorber, release of alkyl phosphoric ester, dye mixture of CI solvent violet 13, and catalyst of dibutyltin dichloride mixture. A multi-layer anti-reflection coating was applied to manufactured polymer eyeglass lenses for both sides using an E-beam evaporation system. The optical properties of the manufactured lenses with the UV and high-energy visible light-blocking function were analyzed by UV-visible spectrophotometry. As a result, the polymer eyeglass lens with a UV absorber of 0.5 wt. % blocked 99% of UV and high-energy visible light shorter than 411 nm. The average transmittance of the polymer eyeglass lens with a UV absorber of 0.5wt.% was 97.9% in the range of 460 ~ 660 nm for photopic eye sensitivity higher than 10%. Therefore, clear image acquisition in photopic vision is possible.

Characteristics of ITZO Thin Films According to Substrate Types for Thin Film Solar Cells (박막형 태양전지 응용을 위한 ITZO 박막의 기판 종류에 따른 특성 분석)

  • Joung, Yang-Hee;Kang, Seong-Jun
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.6
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    • pp.1095-1100
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    • 2021
  • In this study, ITZO thin films were deposited on glass, sapphire, and PEN substrates by RF magnetron sputtering, and their electrical and optical properties were investigated. The resistivity of the ITZO thin film deposited on the glass and sapphire substrates was 3.08×10-4 and 3.21×10-4 Ω-cm, respectively, showing no significant difference, whereas the resistivity of the ITZO thin film deposited on the PEN substrate was 7.36×10-4 Ω-cm, which was a rather large value. Regardless of the type of substrate, there was no significant difference in the average transmittance of the ITZO thin film. Figure of Merits of the ITZO thin film deposited on the glass substrate obtained using the average transmittance in the absorption region of the amorphous silicon thin film solar cell and the absorption region of the P3HT : PCBM organic active layer were 10.52 and 9.28×10-3 Ω-1, respectively, which showed the best values. Through XRD and AFM measurements, it was confirmed that all ITZO thin films exhibited an amorphous structure and had no defects such as pinholes or cracks, regardless of the substrate type.

[Retracted]Case Study of Microseismic Monitoring System Installation based on Underground Mine Communication System ([논문철회]지하광산 갱내통신 기반 미소진동 모니터링 체계 구축 사례)

  • Heo, Seung;Choi, Yongkun
    • Tunnel and Underground Space
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    • v.32 no.2
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    • pp.120-130
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    • 2022
  • In this study, the applicability of the microseismic monitoring system based on the underground mine communication system has been verified by operation test in the domestic underground mine. The microseismic data consists of wavelet data and meta-data for mine safety management, and both data should be transferred, stored, analyzed and managed with proper method according to the purpose and size of each data. In order to select the optimal communication system for the microseismic monitoring system considering the underground environment as well as properties of data, various types of communication system have been tested and compared during operation test after installing the optical cable communication system, 2.4 GHz and 900 MHz wireless communication system through the underground mine tunnel and overground area of the test site. The integrated microseismic monitoring software, which was developed to secure the stability of data management and ease of use, has been updated according to findings from operation test. Through the operation test of the microseismic monitoring system including the communication system and the monitoring software, the technical basis was established corresponding to various requirements of the domestic mine for adoption of the microseismic monitoring system.

Characterization of fine particulate matter during summer at an urban site in Gwangju using chemical, optical, and spectroscopic methods (화학적·광학적·분광학적 방법을 이용한 광주 도심지역 여름철 초미세먼지의 특성)

  • Son, Se-Chang;Park, Tae-Eon;Park, Seungshik
    • Particle and aerosol research
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    • v.17 no.4
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    • pp.91-106
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    • 2021
  • Daily PM2.5 was collected during summer period in 2020 in Gwangju to investigate its chemical and light absorption properties. In addition, real-time light absorption coefficients were observed using a dual-spot 7-wavelength aethalometer. During the study period, SO42- was the most important contributor to PM2.5, accounting for on average 33% (10-64%) of PM2.5. The chemical form of SO42- was appeared to be combination of 70% (NH4)2SO4 and 30% NH4HSO4. Concentration-weighted trajectory (CWT) analysis indicated that SO42- particles were dominated by local pollution, rather than regional transport from China. A combination of aethalometer-based and water-extracted brown carbon (BrC) absorption indicated that light absorption of BrC due to aerosol particles was 1.6 times higher than that due to water-soluble BrC, but the opposite result was found in absorption Ångström exponent (AAE) values. Lower AAE value by aerosol BrC particles was due to the light absorption of aerosol BrC by both water-soluble and insoluble organic aerosols. The BrC light absorption was also influenced by both primary sources (e.g., traffic and biomass burning emissions) and secondary organic aerosol formation. Finally the ATR-FTIR analysis confirmed the presence of NH4+, C-H groups, SO42-, and HSO42-. The presence of HSO42- supports the result of the estimated composition ratio of inorganic sulfate ((NH4)2SO4) and bisulfate (NH4HSO4).

Design and Evaluation of IMI Multilayer Hybrid Structure-based Performance Enhanced Surface Plasmon Resonance Sensor for Biological Analysis (생물학적 분석용 IMI 하이브리드 다중레이어 구조 기반 성능 향상된 표면 플라즈몬 공명 센서의 설계 및 특성 분석)

  • Song, Hyerin;Ahn, Heesang;Kim, Kyujung
    • Korean Journal of Optics and Photonics
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    • v.33 no.4
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    • pp.177-186
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    • 2022
  • The performance of a surface plasmon resonance sensor is evaluated based on the sensitivity (nm/RIU) and sharpness from the full width at half maximum (FWHM) and the peak depth of a resonance peak. These factors are determined by the materials and conformational properties of the sensing structure. In this paper, we investigated an optimized insulator-metal-insulator (IMI) multilayer-based surface plasmon resonance sensor structure to simultaneously achieve high sensitivity, narrow FWHM, and deep peak depth while using gold for the metallic film layer which occurs peak broadening. By adopting the optimized structure, sensitivity of 8,390 nm/RIU, FWHM of 11.92 nm, and a resonance peak depth of 93.1% were achieved for 1.45-1.46 refractive index variation of the sensing layer. With the suggested structure conformation, high sensitivity and resolution of sensing performance can be achieved.

Development of Proto-type Program for Automatic Change Detection and Cueing of Multi-temporal KOMPSAT-5 SAR Imagery (다중시기 KOMPSAT-5 SAR 위성영상의 자동변화탐지알림 프로토타입 프로그램 개발)

  • Chae, Sung-Ho;Oh, Kwan-Young;Lee, Sungu
    • Korean Journal of Remote Sensing
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    • v.38 no.6_4
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    • pp.1955-1969
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    • 2022
  • Most of the public and private users who use national satellite information such as the KOMPSAT series mainly use Electro-Optical and Infrared (EO/IR) satellite images, and the utilization of Synthetic Aperture Radar (SAR) images is relatively insufficient. As KOMPSAT-5 currently in operation, KOMPSAT-6 and micro SAR satellite constellation systems are scheduled to be launched in the future, the demand for utilization of SAR satellite information is increasing in various fields. Accordingly, it is necessary to possess core technology for SAR utilization that can support the utilization of SAR satellite information for users. Due to the all-weather properties of SAR system, change detection technology is a key application technology. However, until now, the development of technology that automatic change detection and cueing using SAR images is insufficient. Through this study, the requirements of automatic change detection and cueing function using multi-temporal KOMPSAT-5 SAR satellite images were derived and a prototype program was developed. This prototype program aims to secure independent SAR utilization technology and promote the utilization of domestic SAR satellite information by practitioners in public sector organizations in Korea.