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관계형 DBMS 사용 환경을 위한 SQL - SDE의 구현
이준호(Joonho Lee),안태호(Taeho Ahn),이윤숙(Yoonsuk Lee),이윤준(Yoonjoon Lee) 한국정보과학회 1988 한국정보과학회 학술발표논문집 Vol.15 No.2
사용자가 단말기에서 대화식으로 질의를 작성하여 데이타베이스에 접근하려면 DBMS가 제공하는 질의어의 구문에 알맞도록 질의를 작성해야 한다. 일반적으로 질의어는 많은 수의 예약어를 포함하는 복잡한 구조의 국문도 제공하기 때문에 일반 사용자들이 질의어를 술달하기에는 오랜 시간이 필요하다. 본 논문에서는 사용자가 SQL 언어로 질의를 작성할 때, 문법적 오류가 없는 질의를 쉽게 작성할 수 있도록, DBMS 사용 환경에 적합한 SQL syntax directed 에디터를 구현하였다. 이 시스템은 사용자가 DBMS가 제공하는 SQL 언어의 구문에 구애받지 않고, 문법적 오류가 없는 질의를 쉽게 작성할 수 있도록 도와준다.
Nickel-based bilayer thin-film anodes for low-temperature solid oxide fuel cells
Lee, Yeageun,Park, Joonho,Yu, Wonjong,Tanveer, Waqas Hassan,Lee, Yoon Ho,Cho, Gu Young,Park, Taehyun,Zheng, Chunhua,Lee, Wonyoung,Cha, Suk Won Elsevier 2018 ENERGY Vol.161 No.-
<P><B>Abstract</B></P> <P>In this study, we investigate the possibility of using Ni-based anodes as alternatives to the Pt-based anodes for thin-film solid oxide fuel cells (SOFCs) operating at low temperatures. Anodes, electrolytes, and cathodes are sequentially sputtered onto a nanoporous substrate. The pure Ni anodes with modified nanostructures exhibit comparable performance as that of the optimized Pt anodes. Furthermore, a Ni/Ni-YSZ bilayer anode fabricated via a co-sputtering method exhibits approximately 37% higher peak power density than does the optimized Pt anode at 500 °C, demonstrating that noble metal anodes can be replaced by Ni-based anodes in low-temperature SOFCs by optimizing the anode nanostructure.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ni anodes with different nanostructures are fabricated for low-temperature SOFCs. </LI> <LI> The Ni anodes are inferior to an optimized Pt anode in terms of catalytic activity. </LI> <LI> A Ni/Ni-YSZ bilayer anode is introduced as an alternative to the Pt anode. </LI> <LI> The bilayer anode successfully substitutes the Pt anode with 37% higher performance. </LI> <LI> The full cell fabrication process is time-efficient and easy to scale-up. </LI> </UL> </P>
Lee, Joonho,Seong, Hyo Suk,Kim, Byoung Jae,Jun, Jong Kwan,Romero, Roberto,Yoon, Bo Hyun De Gruyter 2009 Journal of perinatal medicine Vol.37 No.1
<P>The onset of preterm labor has been proposed to have survival value and to be adaptive in nature. This hypothesis would predict that induced preterm birth may be associated with higher rates of complications than spontaneous preterm birth. The purpose of this study was to determine if there is a difference in the frequency of neonatal respiratory distress syndrome (RDS), the most common neonatal complication, according to the etiology of preterm birth (e.g., preterm labor [PTL], preterm PROM, or pregnancies which ended because of maternal-fetal indications).</P>
Development of box-shaped steel slit dampers for seismic retrofit of building structures
Lee, Joonho,Kim, Jinkoo Elsevier 2017 Engineering structures Vol.150 No.-
<P><B>Abstract</B></P> <P>In this study a steel slit damper is developed by combining four steel slit plates to be used for seismic retrofit of structures. The proposed damper consists of four slit plates integrated into a box shape, and can produce larger damping force in relatively small size compared with the conventional slit plate dampers composed of single slit plate. Cyclic loading tests of two damper specimens are carried out to evaluate their seismic energy dissipation capability. The slit dampers are applied to seismic retrofit of an existing reinforced concrete structure using the procedure developed based on the capacity spectrum method. Nonlinear dynamic analysis of the model structure shows that the dampers installed using the proposed procedure are effective in restraining the building displacement within a given target performance limit state. The time history of the hysteretic energy dissipation shows that most seismic energy is dissipated by the dampers while the structural elements mostly remain elastic.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A steel slit damper is developed by combining four steel slit plates to be used for seismic retrofit of structures. </LI> <LI> Cyclic loading tests of two damper specimens are carried out to evaluate their seismic energy dissipation capability. </LI> <LI> The slit dampers are applied to seismic retrofit of a model structure using capacity spectrum method. </LI> <LI> The dampers are effective in restraining the building displacement within a given target performance limit state. </LI> </UL> </P>
Seismic performance evaluation of moment frames with slit-friction hybrid dampers
Lee, Joonho,Kim, Jinkoo Techno-Press 2015 Earthquakes and structures Vol.9 No.6
This study investigates the seismic energy dissipation capacity of a hybrid passive damper composed of a friction and a hysteretic slit damper. The capacity of the hybrid device required to satisfy a given target performance of a reinforced concrete moment resisting frame designed with reduced design base shear is determined based on the ASCE/SEI 7-10 process, and the seismic performances of the structures designed without and with the hybrid dampers are verified by nonlinear dynamic analyses. Fragility analysis is carried out to investigate the probability of a specified limit state to be reached. The analysis results show that in the structure with hybrid dampers the residual displacements are generally reduced and the dissipated inelastic energy is mostly concentrated on the dampers. At the Moderate to Extensive damage states the fragility turned out to be smallest in the structure with the hybrid dampers.
Lee, Junggoo,Lee, Joonho,Tanaka, Toshihiro,Mori, Hirotaro IOP Pub 2009 Nanotechnology Vol.20 No.47
<P>Phase stabilities of nanometer-sized materials are quite different from those of the corresponding bulk materials. Among the phase stabilities, melting point suppression is one of the most fundamentally important issues. In this work, real-time, atomic-scale direct observation of melting point suppression in nanometer-sized Au particles, along with simple size reduction, was carried out by means of <I>in situ</I> high resolution electron microscopy. Namely, it was confirmed in real space on an atomic scale that a solid-to-liquid transition occurred when the size of a particle, placed on a graphite substrate maintained at 1100 K, decreased to 5 nm during diminution. Furthermore, a monolayer-thick hole was formed on the substrate at the position of the liquid Au particle, probably due to carbon dissolution into the liquid Au particle.</P>