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Selection criteria for oxidation method in total organic carbon measurement
Yoon, GeunSeok,Park, Sang-Min,Yang, Heuiwon,Tsang, Daniel C.W.,Alessi, Daniel S.,Baek, Kitae Elsevier 2018 CHEMOSPHERE - Vol.199 No.-
<P><B>Abstract</B></P> <P>During the measurement of total organic carbon (TOC), dissolved organic carbon is converted into CO<SUB>2</SUB> by using high temperature combustion (HTC) or wet chemical oxidation (WCO). However, the criteria for selecting the oxidation methods are not clear. In this study, the chemical structures of organic material were considered as a key factor to select the oxidation method used. Most non-degradable organic compounds showed a similar oxidation efficiency in both methods, including natural organic compounds, dyes, and pharmaceuticals, and thus both methods are appropriate to measure TOC in waters containing these compounds. However, only a fraction of the carbon in the halogenated compounds (perfluorooctanoic acid and trifluoroacetic acid) were oxidized using WCO, resulting in measured TOC values that are considerably lower than those determined by HTC. This result is likely due to the electronegativity of halogen elements which inhibits the approach of electron-rich sulfate radicals in the WCO, and the higher bond strength of carbon-halogen pairs as compared to carbon-hydrogen bonds, which results in a lower degree of oxidation of the compounds. Our results indicate that WCO could be used to oxidize most organic compounds, but may not be appropriate to quantify TOC in organic carbon pools that contain certain halogenated compounds.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Concentration of organic matter is not suitable to determine oxidation method. </LI> <LI> Chemical structure is a key factor determining oxidation of organic matter. </LI> <LI> Wet chemical oxidation oxidized partially halogenated compounds. </LI> </UL> </P>
Disk-Loaded 다이폴과 Folded 다이폴로 동작하는 Reconfigurable 안테나
박슬기(Seulgi Park),정근석(Geunseok Jeong),추호성(Hosung Choo),오이석(Yisok Oh) 한국전자파학회 2007 한국전자파학회논문지 Vol.18 No.12
본 논문에서는 PIN 다이오드를 사용하여 disk-loaded 다이폴 안테나와 folded 다이폴 안테나로 형상이 변화하는 새로운 구조의 소형 안테나를 개발하였다. 개발된 안테나는 PIN 다이오드의 RF on/off 특성을 이용하여 안테나의 전기적 길이를 변화시켜 이중 대역에서 동작하며, 저주파 대역에서는 높은 복사 저항 값을 가지는 folded 다이폴 안테나로 동작하고 고주파 대역에서는 수평 방향으로 무지향성의 복사 패턴과 수직 방향으로 도넛 형태의 복사 패턴을 가지는 disk-loaded 다이폴 안테나로 동작한다. 제안된 안테나는 20~300 ㎒에서 30 ㎝ 다이폴 안테나에 비해 크기가 소형화 되었음에도 높은 이득을 가진다. 또한, 300~1,300 ㎒에서 80° 이상의 넓은 빔 폭을 가짐으로써 방향 탐지 안테나로 사용이 가능하다. In this paper, we propose a reconfigurable antenna which operates as a disk-loaded dipole antenna and a folded dipole antenna alternatively using RF on/off switches. The antenna can change its effective length to achieve dual-band operation; operates as the folded dipole antenna for stepping up the radiation resistance in low frequency band of 20~300 ㎒, and as the disk-loaded dipole antenna for an omni-directional radiation pattern (horizontal plane) and a donut-shaped radiation pattern (vertical plane) in high frequency band of 300~1.3 ㎓. In the low band, the proposed antenna shows higher gain than a conventional dipole antenna with a reduced antenna size. In the high band, the antenna maintains a broad beamwidth of about 80°, thus the antenna can be applicable to antennas for direction finding applications.
Dongil Shin,Sungnam Kim,Geunseok Jeong,Jaesu Park,Joungwook Park,Ki Jin Han,Jingook Kim [Institute of Electrical and Electronics Engineers 2015 IEEE transactions on electromagnetic compatibility Vol.57 No.4
<P>A common-mode (CM) active filter was designed in a compact package to suppress CM conducted emissions at a switching mode power supply (SMPS). Based on the analytical expressions considering both stability and performance, the design and optimization rules for the proposed active filter have been presented. After verifying its performance by measurements using vector network analysis, the proposed filter was installed in a 200-W SMPS board with 64 and 110 kHz switching frequencies, demonstrating its usefulness by experiments. The performance degradation due to the magnetic saturation and the AEF grounding impedance was also analyzed and investigated.</P>
Common Mode Noise Reduction for an LLC Resonant Converter by Using Passive Noise Cancellation
Younggon Ryu,Sungnam Kim,Geunseok Jeong,Jaesu Park,Duil Kim,Jongwook Park,Jingook Kim,Ki Jin Han 한국전자파학회JEES 2015 Journal of Electromagnetic Engineering and Science Vol.15 No.2
This paper describes the application of a passive noise cancellation method to a prototype inductor-inductor-capacitor (LLC) resonant converter by placing a compensation winding in a transformer to reduce common mode noise. The connection method for the compensation winding is investigated. A circuit analysis is implemented for the displacement currents between the primary and secondary windings in the transformer. The analyzed displacement currents are verified by performing a circuit simulation and a proper compensation winding connection that reduces common mode noise is found. The measurement results show that common mode noise is reduced effectively up to 20 dB in the 1 to 7 MHz frequency region for the prototype LLC resonant converter by using the proposed passive noise cancellation method.
NPL 프로세스 분석 기반 대체투자 표준화를 위한 서비스융합디자인 연구
이철진(Cheoljin Lee),설상훈(Sanghun Sul),박근석(Geunseok Park),김서희(Seohee Kim) 한국문화융합학회 2023 문화와 융합 Vol.45 No.10
본 연구의 목적은 대체투자 시장의 특수성인 가격 불투명성, 정보 비대칭성 등을 해소하기 위한 대체투자 표준화를 설계하여 커뮤니케이션 개선을 위한 서비스디자인을 제시하는 것이다. 이를 위해 부동산담보부 부실채권, 고가품 중 미술품 유통 시장 특성 및 가격 지수 모형 등을 조사하였고, 서비스디자인방법론 중 하나인 서비스 블루프린트(Service Blueprint)를 활용하여 대체투자의 두 가지 형태인 정량자산 및 정성자산 투자과정 분석 및 가치산정을 위한 이해관계자들의 가치 결정 요인을 분석하였다. 이러한 분석을 통해서 대체투자 표준화를 설계하였고, 이를 기반으로 미술품 투자에 대한 사용자 경험을개선할 수 있는 커뮤니케이션 서비스디자인을 제시하였다. The purpose of this study is to design an alternative investment standardization to resolve price opacity and information asymmetry, which are the specific characteristics of the alternative investment market, and to present a service design to improve communication. To this end, bad loans with real estate collateral, art distribution market characteristics, and price index models were examined, and service blueprints, one of the service design methodologies, were used to analyze the investment process of quantitative and qualitative assets, two forms of alternative investment, and to determine the value of stakeholders. Through this analysis, alternative investment standardization was designed, and based on this, a communication service design that can improve the user experience of art investment was presented.