Solvate Ionic Liquid Electrolyte for Li–S Batteries

Dokko, Kaoru,Tachikawa, Naoki,Yamauchi, Kento,Tsuchiya, Mizuho,Yamazaki, Azusa,Takashima, Eriko,Park, Jun-Woo,Ueno, Kazuhide,Seki, Shiro,Serizawa, Nobuyuki,Watanabe, Masayoshi The Electrochemical Society 2013 Journal of the Electrochemical Society Vol.160 No.8

<P>Innovation in the design of electrolyte materials is crucial for realizing next-generation electrochemical energy storage devices such as Li–S batteries. The theoretical capacity of the S cathode is 10 times higher than that of conventional cathode materials used in current Li–ion batteries. However, Li–S batteries suffer from the dissolution of lithium polysulfides, which are formed by the redox reaction at the S cathode. Herein, we present simple solvate ionic liquids, glyme–Li salt molten complexes, as excellent electrolyte candidates because they greatly suppress the dissolution of lithium polysulfides. The molten complexes do not readily dissolve other ionic solutes, which leads to the stable operation of the Li–S battery over more than 400 cycles with discharge capacities higher than 700 mAh g-sulfur<SUP>−1</SUP> and with coulombic efficiencies higher than 98% throughout the cycles. Such high performance has not been realized to the best of our knowledge. Furthermore, the addition of a nonflammable fluorinated solvent, which does not break the solvate structure of the glyme–Li salt molten complexes, greatly enhances the power density of the Li–S battery. The strategic design of electrolyte properties provides opportunities for the development of new electrochemical devices with many different electrode materials.</P>

An Evolutionary Process of Asset Transformation of Financial Intermediaries

Yoon Dokko,Jae-Cheol Kim 서울대학교 경제연구소 1989 Seoul journal of economics Vol.2 No.3

This paper models the evolutionary process of banks whose roles are information production and asset transformation, the latter being a process of issuing liabilities (deposits) and then investing the proceeds in other risky assets. After we establish the "mixed quality equilibrium" in a capital market where managers and investors have asymmetric information about project quality, we derive cost conditions which motivate the emergence of banks as information producers and asset transformers. If asset transformation is a second-best choice relative to information production, asset transformation could be a mechanism for reducing the incentive cost of banks. A necessary condition for asset transformation to be a first-best choice is that banks are less risk averse than investors.

아주대학교 WCU 금융공학사업단

독고윤(Dokko Yoon) 한국산업응용수학회 2009 한국산업응용수학회 학술대회 논문집 Vol.4 No.2

이미지와 텍스트 메시지의 통합 사용자 뷰를 제공하는 전자 우편 시스템

독고세준(Dokko Seh Joon),이택균(Lee Taek Gyeun),이형우(Lee Hyung Woo),윤성현(Yun Sung Hyun),이성환(Lee Seong Whan),김창헌(Kim Chang Hun),김태윤(Kim Tai Yun) 한국정보처리학회 1997 정보처리학회논문지 Vol.4 No.2

E-mail has been widely used for information delivery as an Internet service. As multimedia technologies are developed rapidly, most of the recent Internet information services support multimedia data. E-mail system also needs to support multimedia message. But Internet mail service using simple mail transfer protocol(SMTP) specified in RFC 821/822 handles only ASCII text messages represented with 7-bit code. Each line in the message has the length limitation as well. Those are why it cannot satisfy the diverse users' demands. Multipurpose Internet mail extensions(MIME), which is a modification and supplement of RFC 822, was proposed for supporting transportation of multimedia data. It can solve the limitations of sizes and types in contents of a message. In this study the E-mail system has been designed and implemented according to the MIME standard in order to solve the limitations of transportation of messages regardless of the message content type. Hypertext markup language(HTML) syntax is applied to the mail system, and so it is possible to display a message consisting of different media as an integrated form for the purpose of better understanding a message. No application program is needed for displaying a message including image data, and convenience for users is considered in this system. The future work is to improve the E-mail system so that it may support motion pictures and sound informations. Thereby the perfect multimedia E-mail system providing integrated user''s view will be developed.

Analysis of Elasto-Plastic Dynamic Behavior of Plates Subjected to Low Velocity Impact

Wook Dokko,Moon Saeng Kim 한국정밀공학회 2005 International Journal of Precision Engineering and Vol.6 No.1

In this study, a computer program is developed for analyzing the elasto-plastic dynamic behaviors of the plates subjected to line-loading by a low-velocity impactor. The equilibrium equation associated with the Hertzian contact law is formulated to evaluate the transient dynamic behavior of the impacted plates. Compared with an elastic analysis, the effects of material plasticity are considered. Consequently, in the case of elasto-plastic analysis, impulse decreases, displacements increase and contact duration time is longer than that of the elastic case for the same plate structures. And the time variation of the impacting load is not significant due to the plasticity except at the beginning of impact duration, and the induced stresses of plate are more realistic.

인 - 라인 이미지를 지원하는 HTML 기반 전자 메일 시스템의 설계 및 구현

독고세준(Seh-Joon Dokko),이택균(Taek-Gyun Lee),이형우(Hyung-Woo Lee),윤성현(Sung-Hyun Yoon),김태윤(Tai-Yun Kim) 한국정보과학회 1996 한국정보과학회 학술발표논문집 Vol.23 No.1A

멀티미디어 관련 기술의 급속한 발전으로 최근 정보 서비스는 대부분 멀티미디어를 지원하고 있다. 그러나 RFC 821/822의 SMTP를 사용하는 기존의 전자 메일 서비스는 전달할 수 있는 정보의 종류를 7bit 텍스트만으로 제한하고 있다. 또한 한 라인이 일정 크기 이상을 넘을 수 없어서 사용자 요구에 부합하지 못한다. RFC 822를 수정, 보완한 MIME(Multipurpose Internet Mail Extensions)은 정보의 종류와 크기의 제한을 해결하여 멀티미디어 데이타의 전송을 가능하게 하였다. 본 논문에서는 MIME을 통하여 기존 전자 메일 시스템의 정보 전송상의 제약을 해결하고, HTML을 기반으로 텍스트 내에 이미지를 포함하는 인-라인 이미지를 지원한 전자 메일 시스템을 설계 및 구현하였다. 텍스트 내에 이미지를 포함하여 메일을 구성함으로써 사용자 편의를 더욱 증가시킨 발전된 전자 메일을 실현하였으며, 향후 동화상 및 음성정보 등을 지원하여 통합 멀티미디어 메일 시스템을 구현하는 근간이 될 수 있다.

내수면 양식장을 위한 LPWA망 기반 스마트 급이 시스템 설계

독고세준,Dokko, Sehjoon 한국사물인터넷학회 2016 한국사물인터넷학회 논문지 Vol.2 No.3

IoT기술은 최근 수년간 급격히 발달하였고, 많은 분야에 적용되고 있다. 수산업 분야에서는 IoT 플랫폼을 활용한 양식장 수질관리 시스템이 개발되어 생산성 향상과 근로 환경 개선에 많은 도움을 주고 있다. 본 연구에서는 내수면 양식장 수질관리 시스템에서 더욱 발전하여, 수질 연동형 자동 급이 시스템을 설계함으로써 보다 효율적이고 체계적인 양식장 관리 시스템을 제안한다. IoT 전용망인 LPWA를 활용하여 내수면 양식장 환경에 적합하고, 저전력과 낮은 통신비용으로 상용화를 위한 경제성을 확보하였다. 본 연구를 통하여 내수면 양식 산업의 발전은 물론, 빅데이터 분석을 통한 양식 기술 발전에 일조할 것으로 기대한다. IoT technologies have been rapidly developed in recent years, and applied to many industries. In the field of fisheries, the water quality management system have been developed, helping in improving productivity and working environment. In this paper, we have designed the smart feeding system, interoperable with the water quality system, using LPWA network. LPWA network is an IoT network, which is appropriate to fish farms because of its wide area coverages and low power consumption. We expect this work to contribute to developing the aquaculture technology through the big data analysis with the accumulated data.

빗물의 용도결정을 위한 세균학적 안전성 및 수질 평가

곽동희,독고석,한무영 대한상하수도학회 2003 상하수도학회지 Vol.17 No.5

Recently, there has been an increasing interest to promote the utilization of rainwater. In this paper, concentration of organic compound and heavy metal in rainwater samples was analyzed to examine the hazardous level of rainwater for utilization. And an experiment for separating the opportunistic and pathogenic bacteria was also performed. Unlike the quality of ground water and surface water, only a few couple of bacteria types have found in the rainwater samples. This means that the quality of rainwater is by far safer than other water sources. Many opportunistic colony which inhabits in nature was found in the most of samples while the pathogenic bacteria was not detected. Organic compounds have not found in rainwater. Concentration of heavy metal in it also shows under the regulation of drinking water. Conclusively, on the basis of the analysis results on five samples, rainwater could be used directly for various purpose without additional water treatment process.

재무자료를 이용한 한국통신의 자본비용 결정에 관한 연구

서윤석,독고윤,한봉희 정보통신정책학회 1996 정보통신정책연구 Vol.3 No.1

본 연구는 재무자료를 이용하여 한국통신이 투자한 총자본에 대한 자본비용(Cost of Capital)을 산출한다. 자본비용 산출의 핵심은 베타 도출이다. 한국통신은 비상장인 관계로 주가수익률 자료가 없어 베타를 직접적으로 계산해 낼 수가 없다. 이에 본 연구는 기존의 연구에서 주가수익률과 비례적인 관계가 있다고 밝혀진 회계수익률을 이용하여 간접적으로 한국통신의 베타를 도출한다. 이를 위해 한국통신과 부채비율이 흡사하면서 지난 14년간(1982-1995) 지속적으로 회계수익률 자료와 주가수익률 자료가 이용 가능한 32개 상장기업 표본을 선정한다. 선정된 표본기업에 대하여 회계수익률 변수와 베타와의 상관계수를 추정한다. 이렇게 추정된 상관계수를 한국통신의 회계수익률 변수에 적용함으로써 한국통신의 베타를 도출한다. 회계수익률 변수로서 평균 회계수익률 , 회계변이, 및 회계베타를 측정하였으나 이 중 표본기업에 있어 베타와 유의한 상관관계를 보인 평균 회계수익률과 회계변이만을 베타 도출에 이용하였다. 결과적으로 본 연구가 도출하여 제안한 한국통신의 베타 값은 0.589이며 이 베타 값에 근거한 한국통신의 자기자본비용은 14.78%이고 최종적인 가중평균 자기자본비용은 10.31%이다.

하악 구조체 분석을 위한 다단계 최적 3차원 유한 요소 형성

이형우(Lee Hyung Woo),독고세준(Dokko Seh Joon),이성환(Lee Seong Whan),김창헌(Kim Chang Hun),김태윤(Kim Tai Yun) 한국정보처리학회 1996 정보처리학회논문지 Vol.3 No.7

for the medicla analysis of the three-dimensional structure such as the mandible, it is necessary to reconstruct the structure into the finite number of analyzable elements. The information of the three-dimensional structure can be obtained from the cross-sections of the magnetic resonance image (MRI). A region corresponding to the structure is extracted from the inner part of the cross-section. By the triangulation of the sampled cross-section image, two-dimensional finite elements are generated. There-dimensional finite elements are constructed by matching the two-dimensional finite elements each other in space. In this paper s construction method of the optimal three-dimensional finite elements has been suggested, which uses the adjacent information abstracted from the triangulated two-dimensional finite elements. The elements are classified into the identical property sets by using the adjacent information of the triangulated two-dimensional elements. After applying the multistep matching algorithm to the classified two-dimensional finite elements, the optimal three-dimensional finite elements can be constructed. By analyzing the constructed finite elements, it is possible to get much more useful medical information about the three-dimensional structure of mandible.