• Transactions of the Korean hydrogen and new energy society
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• v.30 no.1
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• pp.21-28
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• 2019

Reversible solid oxide fuel cell (ReSOC) system was integrated with waste steam for electrical energy storage in distributed energy storage application. Waste steam was utilized as external heat in SOEC mode for higher hydrogen production efficiency. Three system configurations were analyzed to evaluate techno-economic performance. The first system is a simple configuration to minimize the cost of balance of plant. The second system is the more complicated configuration with heat recovery steam generator (HRSG). The third system is featured with HRSG and fuel recirculation by blower. Lumped models were used for system performance analyses. The ReSOC stack was characterized by applying area specific resistance value at fixed operating pressure and temperature. In economical assessment, the levelized costs of energy storage (LCOS) were calculated for three system configurations based on capital investment. The system lifetime was assumed 20 years with ReSOC stack replaced every 5 years, inflation rate of 2%, and capacity factor of 80%. The results showed that the exergy round-trip efficiency of system 1, 2, 3 were 47.9%, 48.8%, and 52.8% respectively. The high round-trip efficiency of third system compared to others is attributed to the remarkable reduction in steam requirement and hydrogen compression power owning to fuel recirculation. The result from economic calculation showed that the LCOS values of system 1, 2, 3 were 3.46 ¢/kWh, 3.43 ¢/kWh, and 3.14 ¢/kWh, respectively. Even though the systems 2 and 3 have expensive HRSG, they showed higher round-trip efficiencies and significant reduction in boiler and hydrogen compressor cost.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.33-42
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• 2012

Rapid evolution of wired and wireless technologies results in various types of embedded systems, and the software to be embedded into those devices now needs the flexibility rather than the fixedness which was well-known property for the embedded software in the past. Mobile agent is one of the useful distributed technologies of reducing network load and latency because of its disconnected operations and high asynchrony. In this paper, a component-based mobile agent framework, called EmHUMAN, is designed and implemented for structural embedding into the devices showing different functions and resource constraints. It consists of 3 layers of components. Based on those components, a structural embedding, considering resource constraints of required functions, amount of storage space, computing power, network bandwidth, ${\ldots} $ etc can be performed. The components in each layer can be extended with addition of new components, removing some components and modifying components. EmHUMAN plays the role of a framework for developing mobile agent based distributed systems. It is also a mobile agent system by itself. EmHUMAN provides several utilities as built-in API's, and thus high effectiveness in programming mobile agents can be achieved.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.2
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• pp.188-199
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• 2000

This paper presents an efficient stable logging scheme for the distributed shared memory system based on the lazy release consistent memory model. In the proposed scheme, inter-process dependency is traced and stable logging is performed when the dependency relation between processes actually happens. With the dependency tracking, the proposed scheme requires much less frequency of stable logging, comparing with the previous schemes in which stable logging is performed whenever any information transfer happens between processes. Also, in the proposed scheme, every data item accessed by a process is not logged, but only the access information is logged in the stable storage. For the recovery from a failure, the correct version of the accessed data items can be effectively traced by using the logged access information. As a result, the amount of logged information is also reduced.

• The KIPS Transactions:PartA
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• v.12A no.2 s.92
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• pp.171-180
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• 2005

In distributed systems data are replicated and stored at several nodes to increase the availability and overall performance. Here Quorum protocol doffing a certain set of replicas required for read/write operation exists for global concurrency control. One of the representative replication Protocols - the Tree Quorum protocol - has a drawback of rapidly growing number of replicas as the level increases, while the Grid protocol requires the same operation cost even without any failure. In this paper, thus, we propose a new replication protocol called hybrid protocol which capitalizes the merits of the existing protocols and solves the problems of them at the same time. The proposed hybrid protocol has very low operation cost in the absence of failure like the tree quorum protocol, and has relatively lower operation cost and higher availability than existing protocols when failure occurs by employing tree architecture as the overall organization while each level of the tree is organized as a row of a grid architecture. It is thus effective to be applied to survival storage system. We conduct cost and availability analysis of the proposed protocol through mathematical modeling, and response time and throughput are compared with those of the Tree Quorum protocol through computer simulation.

• The KIPS Transactions:PartC
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• v.12C no.1 s.97
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• pp.129-136
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• 2005

WebDAV extends the web communication protocol HTTP/1.1 to provide a distributed authoring and versioning across the Internet. A property management, the principal ability of WebDAV, has many advantages for managing and utilizing additional information of server resources as well as supports a role of storage. Most WebDAV Application systems currently available are using WebDAV for providing simple storage space, not for the functionality of property management. However, to develop an advanced application such as a collaborative system based on WebDAV, it is very important to design and utilize user-defined WebDAV properties. In this paper, we propose DavSUDP(WebDAV Simple User-defined Property Definition Protocol) that describes XML-based configurations representing WebDAV user-defined properties and their processing steps. DavSUDP enables WebDAV servers to effectively manage user-defined properties in developing WebDAV-based applications. To show this, we extended the Apache mod_dav module to support DavSVDP and developed the OpenSpace in the iPlace collaborative system using the extended Apache web server.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1905-1912
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• 2017

In recent years, Ulaanbaatar, a capital of Mongolia has witnessed major problem that air quality reaches hazardous level during the winter season. Coal combustion for heating of every house in "Ger" district is main reason. One way to reduce the air pollution is mass usage of electric heater. However, there are several difficulties such as overload and degradation of transformers and other equipment used in distribution and transmission systems as well as power shortage occurrence in evening peak period due to residential consumption. This study aims to contribute for solving the air pollution and power shortage problem in Mongolia. One possible solution could be distributed generation (DG) with photovoltaic (PV) penetration. In this study, PV with energy storage (ES) hybrid system to reduce peak load is analyzed. We proposed the suitable structure of PV-ES hybrid for Mongolian household, and suggested several operation scenarios. Optimal operation algorithm is carried out based on a comparison aspect from economical, grid impact and PV penetration possibility. The economic analyse shows annual income of 520USD, and has a payback period of 8 years for selected scenario. The proposed PV-ES system structure is verified by experimentation set on the building rooftop in city center. The suggested scenario is planned to apply for system in further research.

• The Journal of Advanced Prosthodontics
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• v.10 no.4
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• pp.308-314
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• 2018

PURPOSE. Plasma activation of hydrophobic zirconia surfaces might be suitable to improve the bond strength of luting materials. The aim of this study was to analyze the influence of nonthermal argon-plasma on the shear bond strength (SBS) between zirconia and different combinations of 10-MDP adhesive systems and luting composites after artificial aging. MATERIALS AND METHODS. Two hundred forty Y-TZP specimens were ground automatically with $165{\mu}m$ grit and water cooling. Half of the specimens received surface activation with nonthermal argon-plasma. The specimens were evenly distributed into three groups according to the adhesive systems ([Futurabond U, Futurabond M, Futurabond M + DCA], VOCO GmbH, Germany, Cuxhaven) and into further two subgroups according to the luting materials ([Bifix SE, Bifix QM], VOCO GmbH). Each specimen underwent artificial aging by thermocycling and water storage. SBS was measured in a universal testing machine. Statistical analysis was performed using ANOVA and $Scheff{\grave{e}}$ procedure with the level of significance set to 0.05. RESULTS. Surface activation with nonthermal plasma did not improve the bond strength between zirconia and the tested combinations of adhesive systems and luting materials. The plasma-activation trended to reveal higher bond strength if the self-etch luting material (Bifix SE) was used, irrespective of the adhesive system. CONCLUSION. Plasma-activation seems to be suitable to improve bond strength between zirconia and self-etch resin materials. However, further research is necessary to identify the influence of varying plasma-parameters.

• Natural Product Sciences
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• v.9 no.4
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• pp.264-269
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• 2003

The rhizome of Acorus calamus Linn. is commonly known as "Vacha" in indigenous systems of medicine. It is distributed in marshy tracts of Kashmir, Sirmaur (Himachal Pradesh), Manipur and the Naga hills. It is regularly cultivated in Koratagere Taluk in Karnataka and other parts of India. This study deals with the detailed pharmacognostical evaluation of the dried rhizomes of Acorus calamus collected from DehraDun (Uttaranchal), Lucknow (Uttar Pradesh). The commercial sample procured from Delhi market was also evaluated to observe the difference between collected and market samples. Dried rhizome is vertically compressed, pale yellow to dark brown and occasionally orangish brown in colour. Transverse section showed two distinct region with scattered, concentric vascular bundles surrounded by fibrous bundle sheath. Some vascular bundles just beneath the endodermis devoid of bundle sheath. Though the botanical and physico-chemical characters of all the samples were quite similar but some variations were observed in High Performance Thin Layer Chromatography (HPTLC) fingerprint profile, the essential oil content and total percentage of asarone which was found to be highest in Lucknow and lowest in Delhi market sample. These variations may be explained due to some edaphic factors or storage conditions. An attempt was also made to test antioxidant activity (in vitro) and it was found to be 88% at 0.2 g/ml concentration.

• The KIPS Transactions:PartD
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• v.10D no.1
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• pp.117-124
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• 2003

The system implemented in this paper partitions and stores specimen data captured by a light microscope on distributed or parallel systems. Users ran observe images on computers as we use a physical microscope. Based on the client-server computing model, the system consists of client, coordinator, and data manager. Three components communicate messages. For retrieving images, we implemented the client program with necessary functions for educational applications such at image mark and text annotation, and defined the communication protocol. We performed the experiment for introducing a tape storage which stores a large volume of data. The experiment results showed performance improvement by data partitioning and indexing technique.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.50-53
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• 2016

Image processing techniques play an increasingly important role in many aspects of our daily life. For example, it has been shown to improve agricultural productivity in a number of ways such as plant pest detecting or fruit grading. However, massive quantities of images generated in real-time through multi-devices such as remote sensors during monitoring plant growth lead to the challenges of big data. Meanwhile, most current image processing systems are designed for small-scale and local computation, and they do not scale well to handle big data problems with their large requirements for computational resources and storage. In this paper, we have proposed an IPABigData (Image Processing Algorithm BigData) platform which provides algorithms to support large-scale image processing in agriculture based on Hadoop framework. Hadoop provides a parallel computation model MapReduce and Hadoop distributed file system (HDFS) module. It can also handle parallel pipelines, which are frequently used in image processing. In our experiment, we show that our platform outperforms traditional system in a scenario of image segmentation.