Applying Formal Methods to Modeling and Analysis of Real-time Data Streams

Kapitanova, Krasimira,Wei, Yuan,Kang, Woo-Chul,Son, Sang-H. Korean Institute of Information Scientists and Eng 2011 Journal of Computing Science and Engineering Vol.5 No.1

Achieving situation awareness is especially challenging for real-time data stream applications because they i) operate on continuous unbounded streams of data, and ii) have inherent realtime requirements. In this paper we showed how formal data stream modeling and analysis can be used to better understand stream behavior, evaluate query costs, and improve application performance. We used MEDAL, a formal specification language based on Petri nets, to model the data stream queries and the quality-of-service management mechanisms of RT-STREAM, a prototype system for data stream management. MEDAL's ability to combine query logic and data admission control in one model allows us to design a single comprehensive model of the system. This model can be used to perform a large set of analyses to help improve the application's performance and quality of service.

Formation of self-assembled nanoscale graphene/graphene oxide photomemristive heterojunctions using photocatalytic oxidation

Kapitanova, Olesya O,Panin, Gennady N,Cho, Hak Dong,Baranov, Andrey N,Kang, Tae Won IOP 2017 Nanotechnology Vol.28 No.20

<P>Photocatalytic oxidation of graphene with ZnO nanoparticles was found to create self-assembled graphene oxide/graphene (G/GO) photosensitive heterostructures, which can be used as memristors. Oxygen groups released during photodecomposition of water molecules on the nanoparticles under ultraviolet light, oxidized graphene, locally forming the G/GO heterojunctions with ultra-high density. The G/GO nanostructures have non-linear current–voltage characteristics and switch the resistance in the dark and under white light, providing four resistive states at room temperature. Photocatalytic oxidation of graphene with ZnO nanoparticles is proposed as an effective method for creating two-dimensional memristors with a photoresistive switching for ultra-high capacity non-volatile memory.</P>

Resistive switching in graphene/graphene oxide/ZnO heterostructures

Kapitanova, O. O.,Panin, G. N.,Kononenko, O. V.,Baranov, A. N.,Kang, T. W. 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. No.

Planar and vertical heterostructures based on graphene/graphene oxide/ZnO nanorods were investigated using optical and electrical characterizations. ZnO nanorods grown on graphene substrate by using the hydrothermal method were used for local oxidation of graphene and the formation of self-assembled graphene/graphene oxide lateral and vertical heterostructures under an electric field. The graphene substrates were prepared by deposition of graphene oxide suspensions, followed by thermal reduction or the growth of graphene by using chemical vapor deposition. The vertical heterostructure demonstrated well-reproducible resistive switching for low offset voltage and could be used to fabricate high-density memory devices with low power consumption.

Applying Formal Methods to Modeling and Analysis of Real-time Data Streams

Krasimira Kapitanova,Yuan Wei,Woochul Kang,Sang H. Son 한국정보과학회 2011 Journal of Computing Science and Engineering Vol.5 No.1

Achieving situation awareness is especially challenging for real-time data stream applications because they i) operate on continuous unbounded streams of data, and ii) have inherent realtime requirements. In this paper we showed how formal data stream modeling and analysis can be used to better understand stream behavior, evaluate query costs, and improve application performance. We used MEDAL, a formal specification language based on Petri nets, to model the data stream queries and the quality-of-service management mechanisms of RT-STREAM, a prototype system for data stream management. MEDAL’s ability to combine query logic and data admission control in one model allows us to design a single comprehensive model of the system. This model can be used to perform a large set of analyses to help improve the application’s performance and quality of service.

Resistive Switching in Graphene/Graphene Oxide/ZnO Heterostructures

O. O. Kapitanova,파닌,O. V. Kononenko,A. N. Baranov,강태원 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.10

Planar and vertical heterostructures based on graphene/graphene oxide/ZnO nanorods were investigatedusing optical and electrical characterizations. ZnO nanorods grown on graphene substrateby using the hydrothermal method were used for local oxidation of graphene and the formation ofself-assembled graphene/graphene oxide lateral and vertical heterostructures under an electric field. The graphene substrates were prepared by deposition of graphene oxide suspensions, followed bythermal reduction or the growth of graphene by using chemical vapor deposition. The verticalheterostructure demonstrated well-reproducible resistive switching for low offset voltage and couldbe used to fabricate high-density memory devices with low power consumption.

Synthesis and Properties of Graphene Oxide/Graphene Nanostructures

O. O. Kapitanova,파닌,A. N. Baranov,강태원 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.10

We report preparation of graphene oxide (GO)/graphene (G) nanostructures and their structural, optical and electrical properties. GO was synthesized through oxidation of graphite by using the modified Hummer’s method, in which a long oxidation time was combined with a highly effective method for purifying the reaction products. The obtained GO was partially reduced (r-GO) by adding ascorbic acid and thermal annealing. An electrical reduction/oxidation process in r-GO under an electric field was used to form and control the GO/G nanostructures and the potential barrier at the interface. After the treatment, the ratio of the intensity of peak G (1578 cm−1) to that of peak D (1357 cm−1) in Raman spectra of the samples is increased, which is attributed to an increase in the ratio between the sp2 and sp3 regions. The electrical and the luminescence characteristics of the GO/G nanostructures were investigated.

Spatially-resolved Study of the Luminescence from ZnO/MgO Core-shell Nanocrystal Structures

파닌,Andrey Baranov,Olesya Kapitanova,강태원 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.3

The luminescent properties of core-shell nanocrystal structures were investigated with high spatial resolution. The composites consisting of ZnO/MgO core/shell nanoheteroparticles showed an increase in the relative intensity of the green luminescence after annealing while a suppression of green luminescence from samples of ZnO tetrapods in a MgO nanoparticle matrix was observed. Combined spatially-resolved combined through-the-lens-detector (TLD) and cathodoluminescence (CL) measurements revealed that the depletion of electrons in the ZnO nanocrystals could lead to a suppression of the luminescence.

실시간 임베디드 센서 네트워크 시스템에서 강건한 데이터, 이벤트 및 프라이버시 서비스 기술

정강수(Kangsoo Jung),Krasimira Kapitanova,손상혁(Sang H. Son),박석(Seog Park) 한국정보과학회 2010 정보과학회논문지 : 데이타베이스 Vol.37 No.6

실시간 임베디드 센서 네트워크 시스템에서의 이벤트 감지는 대부분 현실세계에서 수집된 센서 데이터들의 조합에 기반한다. 이에 최근에 이루어진 연구들에선 센서 데이터들을 수집, 집계하는 낮은 수준의 다양한 메커니즘들을 제안하였다. 그러나 실시간에서 연속적으로 발생하는 복잡한 이벤트들의 감지와 다양한 종류의 센서들로부터 입력되는 실시간 데이터의 처리를 위한 시스템에 대한 솔루션은 보다 많은 연구를 필요로 한다. 즉, 경량의 데이터 혼합이 가능하고 많은 컴퓨팅 자원을 필요로 하지 않는 실시간 이벤트 감지 기법이 필요하다. 이벤트 감지 프레임워크는 실시간 모니터링과 센서 데이터의 도착으로 일어나는 데이터 융합 메커니즘을 통하여 적시성과 임베디드 센서 네트워크의 자원 요구량을 감소시킬 수 있는 잠재력을 지니고 있다. 또한 임베디드 센서 네트워크 시스템이 신뢰성을 지닐 수 있도록 하기 위한 기반 기술인 프라이버시를 보장할 수 있는 익명화 기술을 설명한다. The majority of event detection in real-time embedded sensor network systems is based on data fusion that uses noisy sensor data collected from complicated real-world environments. Current research has produced several excellent low-level mechanisms to collect sensor data and perform aggregation. However, solutions that enable these systems to provide real-time data processing using readings from heterogeneous sensors and subsequently detect complex events of interest in real-time fashion need further research. We are developing real-time event detection approaches which allow light-weight data fusion and do not require significant computing resources. Underlying the event detection framework is a collection of real-time monitoring and fusion mechanisms that are invoked upon the arrival of sensor data. The combination of these mechanisms and the framework has the potential to significantly improve the timeliness and reduce the resource requirements of embedded sensor networks. In addition to that, we discuss about a privacy that is foundation technique for trusted embedded sensor network system and explain anonymization technique to ensure privacy.

Phonon anharmonicities in supported graphene

Kolesov, Egor A.,Tivanov, Mikhail S.,Korolik, Olga V.,Kapitanova, Olesya O.,Cho, Hak Dong,Kang, Tae Won,Panin, Gennady N. Elsevier 2019 Carbon Vol.141 No.-

<P><B>Abstract</B></P> <P>The paper presents temperature-dependent Raman studies of anharmonic phonon properties of graphene as-grown on copper, transferred to copper, SiO<SUB>2</SUB>/Si, and Al<SUB>2</SUB>O<SUB>3</SUB>, as well as nitrogen-doped graphene on SiO<SUB>2</SUB>/Si. Different G and 2D peak position and linewidth temperature dependencies were obtained in the temperature range of 20–294 K, upon which anharmonic constants for 3- and 4-phonon processes were determined. Values of anharmonic constants obtained from G peak shift for undoped graphene on dielectric substrates were quantitatively close to both experimental results for unsupported graphene and theoretical predictions reported in the literature, while the values for graphene as-grown on copper were almost two orders of magnitude greater. The results were analyzed in terms of substrate effect on phonon properties of graphene. The present study is useful for taking into account anharmonic phonon effects in graphene when designing graphene-based nanoelectronic devices.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>