http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
주파수-전압 변환 방식 스펙트럼 센싱을 이용한 채널 선택적 RF시스템
이희종(Heejong Lee),이석재(Seok-Jae Lee),이경주(Kyoung-Joo Lee),김영식(Young-Sik Kim),임종식(Jongsik Lim),한상민(Sang-Min Han) 한국정보기술학회 2011 한국정보기술학회논문지 Vol.9 No.2
In this paper, a channel selective RF receiver system is proposed for low-power sensor networks. The proposed system utilizes a frequency-voltage conversion technology in order to recognize received frequency channels at a RF front-end. The 5㎒-channel allocation of the system is verified for OOK modulated 10Mbps NRZ digital data at 2.4-2.48㎓ ISM band from simulated results. In addition, the experimental results have presented effective sensing voltage resolution to recognize the existence of a valid signal for high-speed spectrum cognition. Moreover, because the proposed system has been designed with the spectrum sensing circuit and the detecting circuit simultaneously, it is expected to contribute to the efficient system design technology, small size, and low power consumption.
Power controlled FM-UWB system with a wideband RF carrier for body area network applications
Lee, Heejong,Lee, Seok-Jae,Yoon, Won-Sang,Han, Sang-Min Cambridge University Press 2014 International Journal of Microwave and Wireless Te Vol.6 No.5
<P>An FM-ultra-wideband (UWB) system with a wideband RF carrier (WRC) is proposed for wireless body area network applications. The proposed system can control the channel power by means of an adjustable carrier bandwidth (BW), while the conventional one with a CW carrier (CWC) makes use of peak power control. The implemented WRC system performances have been evaluated for the WRC generation and digital data transmission. In addition, transmission performances have been compared with that of a conventional CWC system by bit-error-rate (BER) tests. For random data of a 2<SUP>9</SUP>−1 pattern at a data-rate of 64 kbps, in spite of the flexible carrier BW, the WRC system has presented excellent transmission capability compared with that of the CWC system.</P>
Lee, Stanfield Youngwon,Chung, Dong Young,Lee, Myeong Jae,Kang, Yun Sik,Shin, Heejong,Kim, Mi-Ju,Bielawski, Christopher W.,Sung, Yung-Eun American Chemical Society 2016 The Journal of Physical Chemistry Part C Vol.120 No.43
<P>This study was focused On elucidating the origin of the catalytic activity displayed by non-precious-metal-based, oxygen reduction reaction (ORR) catalysts before and after heat treatment. Electrochemical measurements were recorded using a series of metal phthalocyanines calculated to exhibit varying oxygen adsorption energies before and after heat treatment at a temperature Sufficiently high to facilitate degradation. Collectively, the results indicate that while the oxygen adsorption is germane to the catalytic activity before heat, treatment, the ORR appears to proceed through. a different pathway that is not dependent on adsorption energy after heat treatment. These conclusions help to explain the high catalytic activities exhibited by carbon- or nitrogen-based materials containing metal ions after heat treatment and may lead to the realization of substitutes for ORB. catalysts that utilize precious transition metals.</P>
Lee, Myeong Jae,Kang, Jin Soo,Ahn, Docheon,Chung, Dong Young,Park, Subin,Son, Yoon Jun,Yoo, Ji Mun,Shin, Heejong,Kang, Yun Sik,Sung, Nark-Eon,Lee, Kug-Seung,Sung, Yung-Eun Elsevier 2017 ELECTROCHIMICA ACTA Vol.245 No.-
<P><B>Abstract</B></P> <P>Development of Pt-free electrocatalysts for oxygen reduction reaction (ORR) is one of the most important tasks for fuel cell commercialization. Various Mn compounds have been proposed as catalysts for ORR, but poor activity and stability necessitate further advances for their practical utilization. In this study, we demonstrate a lithium manganese phosphate-carbon composite (LMP-C) as a highly active and durable electrocatalyst for ORR in alkaline medium. LMP-C, synthesized by the solid-state method, exhibited significantly enhanced electrical conductivity and electrochemical properties, which led to a substantial increase in ORR performance. Comparison between LMP-C and the manganese phosphate-carbon composite, based on various physicochemical characterizations, revealed a high preference for the formation of the Mn<SUP>3+</SUP> state on the surface of LMP-C that resulted in effective charge transfer during oxygen reduction. Moreover, the excellent stability of LMP-C was confirmed by carrying out 3000 cycles of the accelerated durability test, in which no drop in ORR performance was observed.</P>
Engineering Titanium Dioxide Nanostructures for Enhanced Lithium-Ion Storage
Lee, Dae-Hyeok,Lee, Byoung-Hoon,Sinha, Arun K.,Park, Jae-Hyuk,Kim, Min-Seob,Park, Jungjin,Shin, Heejong,Lee, Kug-Seung,Sung, Yung-Eun,Hyeon, Taeghwan American Chemical Society 2018 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.140 No.48
<P>Various kinds of nanostructured materials have been extensively investigated as lithium ion battery electrode materials derived from their numerous advantageous features including enhanced energy and power density and cyclability. However, little is known about the microscopic origin of how nanostructures can enhance lithium storage performance. Herein, we identify the microscopic origin of enhanced lithium storage in anatase TiO<SUB>2</SUB> nanostructure and report a reversible and stable route to achieve enhanced lithium storage capacity in anatase TiO<SUB>2</SUB>. We designed hollow anatase TiO<SUB>2</SUB> nanostructures composed of interconnected ∼5 nm sized nanocrystals, which can individually reach the theoretical lithium storage limit and maintain a stable capacity during prolonged cycling (i.e., 330 mAh g<SUP>-1</SUP> for the initial cycle and 228 mAh g<SUP>-1</SUP> for the 100th cycle, at 0.1 A g<SUP>-1</SUP>). In situ characterization by X-ray diffraction and X-ray absorption spectroscopy shows that enhanced lithium storage into the anatase TiO<SUB>2</SUB> nanocrystal results from the insertion reaction, which expands the crystal lattice during the sequential phase transition (anatase TiO<SUB>2</SUB> → Li<SUB>0.55</SUB>TiO<SUB>2</SUB> → LiTiO<SUB>2</SUB>). In addition to the pseudocapacitive charge storage of nanostructures, our approach extends the utilization of nanostructured TiO<SUB>2</SUB> for significantly stabilizing excess lithium storage in crystal structures for long-term cycling, which can be readily applied to other lithium storage materials.</P> [FIG OMISSION]</BR>
이희종(Lee, HeeJong),조재영(Cho, Jaeyoung) 한국비교사법학회 2018 비교사법 Vol.25 No.2
최근 암호화폐에 관심이 높아지면서 투자를 하는 사람들이 급속도로 증가를 하였다. 최초의 암호화폐로는 비트코인을 들 수 있는데, 이는 채굴에 성공한 사람에게 비트코인을 지급하도록 설계되어 있다. 비트코인은 블록체인 시스템을 이용해서 채굴을 한 사람에게 코인이 지급되도록 설계되어 있다. 비트코인이 나온 이후에 이더리움, 리플 등의 다양한 형태의 알트코 인들이 등장하여 거래되고 있다. 이들 암호화폐를 가상화폐라고 부르는 경우도 많은데, 암호학에 기반을 해서 설계된 특징이 있기 때문에 암호화폐라는 명칭을 사용하는 것이 타당하다. 암호화폐는 현재 결제수단으로 사용하기에는 어려운 점이 있지만, 지급수단으로 사용하도록 한 업체들이 다수 존재한다. 또한 많은 사람들이 실제로 투자를 하고 있기 때문에 가치저장의 수단으로서도 기능을 하고 있다고 볼 수가 있기 때문에 화폐로서의 기능을 일부 수행하고 있다고 볼 수 있다. 또한 암호화폐는 실제 거래가 되고 있으며 암호화폐 거래가 불법적인 것은 아니기 때문에 당연히 자산으로서의 성격을 가지고 있다. 암호화폐가 현행 자본시장법에서 규정하고 있는 금융투자상품은 아니지만 투자성은 존재하기 때문에 금융투자상품으로 인정을 해서 투자자를 보호하는 것이 바람직하다. 암호화폐업자로서 활동을 하려면 일정 수준 이상의 자기자본이 필요하고 감독당국에 등록을 하도록 하여야 한다. 투자자 보호를 위해서는 암호화폐업자는 주식회사 형태로 설립하도록하여 외부감사를 받도록 하여야 하며, 투자자와의 이해상충 방지체계를 갖추어야 한다. 또한 해킹 방지를 위해서 적정한 수준의 전산시스템을 구비하여야 하며, 처벌을 강화해서 불공정한 거래로 올린 이득을 환수하여야 한다. CryptoCurrency is a newly developed type of decentralized digital, cryptocurrency that has no physical form. The largest characteristics of a CryptoCurrency are that it is a distributedtype virtual currency using peer to peer(P2P) technology. The possibility that the cryptocurrency is to replace the existing national currency is still uncertain. It is also important CryptoCurrency s legal status and the possibility of a government regulation. While some countries have explicitly allowed their use and trade, others have banned or restricted it. Some criticize the posibility of facilitating money laundering, tax evasion, and trade in illegal drugs. As of April 2018, there were 3500 and growing cryptocurrencies in existence. Korea s cryptocurrency have already exceeded the volume of large financial centers. There is no question that cryptocurrency is one of the hottest topics in South Korea. About 3 million people in South Korea are estimated to have invested in cryptocurrencies. Many are betting their incomes and even retirement packages on bitcoins and other virtual currencies. Cryptocurrency trade in Korea is similar to speculation and gambling. But Korea has no regulations against cryptocurrency. Korea’s financial watchdog unveiled a set of guidelines to employ a real-name transaction system for cryptocurrency.