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A highly selective fluorescent sensor for Cu2+ based on naphthalimide containing aza-crown ether
Sumin Jeon,이성만,Yeonghwan Choi,김미라,이송이 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.2
The development of a fluorogenic chemosensors with high sensitivity for copper ion (Cu2+) has been receiving great attention in recent years because of their potential application in clinical biochemistry and the environment studies. In the present study, we designed and synthesized a fluorescent probe, Np-azaCE, with 1,8-naphthalimides as a core structure and 1,4-diaza-9-crown-3-ether as a copper ion tweeze, which showed selective and sensitive fluorometric change upon addition of a copper ion. The Np-azaCE chemosensor was highly selective for Cu2+ over the other metal ions with fluorescent quenching. Finally, the Cu2+ detection limit and job's plot of Np-azaCE were calculated using UV?visible spectrophotometer and fluorescence spectrophotometer.
Anodic Dissolution Behavior of Zr-Nb Alloy in Chloride-based Molten Salts
Jungho Hur,Yeonghwan Jeon,Seungmin Ohk,Jaeyeong Park 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1
Zirconium(Zr) alloys are commonly used in the nuclear industry for applications such as fuel cladding and pressure tubes. To minimize the levels and volumes of radioactive waste, molten salts have been employed for decontaminating Zr alloys. Recently, a two-step Zr metal recovery process, combining electrolysis and thermal decomposition, has been proposed. In the electrolysis process, potentiostatic electrorefining is utilized to control the chemical form of electrodeposits(ZrCl). Although Zr metals are expected to dissolve into molten salts, reductive alloy elements can also be co-dissolved and deposited on the cathode. Therefore, a better understanding of the anodic side’s response during potentiostatic electrorefining is necessary to ensure the purity of recovered Zr and long-term process operation. As the first step, potentiodynamic polarization curves were obtained using Zr, Nb, and Zr-Nb alloy to investigate the anodic dissolution behavior in the molten salts. Nb, which has a redox potential close to Zr, and Zr exhibit active or passivation dissolution mechanisms depending on the potential range. It was confirmed that Zr-Nb alloy also has a passivation region between -0.223 to -0.092 V influenced by the major elements Zr and Nb. Secondly, active dissolution of Zr-Nb was performed in the range of -0.9 to -0.6 V. The dissolution mechanism can be explained by percolation theory, which is consistent with the observed microstructure of the alloy. Thirdly, passivation dissolution of Zr, Nb, and Zr-Nb alloy was investigated to identify the pure passivation products and additional products in the Zr-Nb alloy case. K2ZrCl6 and K3NbCl6 were identified as the pure passivation products of the major elements. In the Zr-Nb alloy case, additional products, such as Nb and NbZr, produced by the redox reaction of nanoparticles in the high viscous salt layer near the anode, were also confirmed. The anodic dissolution mechanism of Zr-Nb alloy can be summarized as follows. During active dissolution, only Zr metal dissolves into molten salts by percolation. Above the solubility near the anode, passivation products begin to form. The anode potential increases due to the disturbance of passivation products on ion flow, leading to co-dissolution of Nb. When the concentration of Nb ion exceeds the solubility, a passivation product of Nb also forms. In this scenario, a high viscous salt layer is formed, which traps nanoparticles of Zr metal, resulting in redox behavior between Zr metal and Nb ion. Some nanoparticles of Zr and Nb metal are also present in the form of NbZr.
천대녕(Daenyung Chun),차영환(Yeonghwan Tscha),강영만(Youngman Kang),전광일(Gwangill Jeon),양선희(Sunhee Yang),이영희(Younghee Lee) 한국정보과학회 1988 한국정보과학회 학술발표논문집 Vol.15 No.2
MORTOS(Message-Oriented Real-Time Operating System)는 통신 소프트웨어에 실시간 및 동시 처리 기능을 제공하는 목적으로 당 연구소에서 설계, 구현된 운영체제이다. 이는 event에 따라 스케쥴링되는 event-driven 방식으로, 정상 동작시에 시분할에 따른 context 스위칭과 프로세스의 상태 관리 그리고 인터럽트 처리에 따르는 부담을 최소화하여 최상의 성능을 갖도록 하였다. 그리고 강력한 오류 처리 기능을 통해 고신뢰도를 요구하는 시스템에 적합하도록 하였으며, CHILL과 같이 언어 확장개념을 통해 사용자로 하여금 쉽게 이용할 수 있도록 인터페이스를 간단히 하였다.
이동 통신망을 위한 도시지역에서의 위치 등록 발생율에 관한 연구
박정환(Junghwan Park),전민희(Minheui Jeon),차영환(Yeonghwan Tscha),이균하(Kyoon Ha Lee) 한국정보과학회 1993 한국정보과학회 학술발표논문집 Vol.20 No.1
이동 가입자(mobile station)에 대한 위치정보의 신속한 처리는 이동 통신망에 있어 필수적이다. 특히, 서울과 같은 대도시 지역에서의 이동 가입자의 빈번한 위치 이동은 트래픽의 폭주를 낳을 수 있기 때문에 위치정보의 신속한 처리를 위해 위치 등록기(location register)의 적절한 위치 선정이 중요하다. 본 논문에서는 도로를 중심으로한 정방형 형태의 도심지에 있어 이동 가입자의 트래픽 이동 형태를 반영한 위치 등록 발생률의 분석과 하나의 위치 등록기에 수용 가능한 위치 영역(location area)수의 산정과 이에 따른 위치 등록 발생률을 분석하였다. 분석 결과 본 연구에서 제안된 방법은 대도시 밀집지역에 있어 위치 등록기의 설치 위치 선정과 위치 등록 발생률의 예측에 매우 유용함을 알 수 있었다.