• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.491.1-491.1
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• 2014

Heteroatom phosphorous-doped graphene aerogel (PGA) with high surface area is successfully synthesized via hydrothermal method for high power and energy supercapacitors, including the advantage of three dimensional internetwork and constitutive graphene skeletons. The morphology of PGA was investigated by the scanning electron microscope, transmission electron microscope. The chemical structure and circumstances were confirmed by Raman and X-ray photoelectron spectroscopy, the phosphorus is successfully incorporated with the graphene sheets. As evidenced by electrochemical measurements, cyclic voltammetry and galvanostatic charge discharge, the hierarchically PGA has an unprecedented high capacitance, which contributes to the excellent high-rate performance of this material for supercapacitor application.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.140-141
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• 2014

차세대 전극 재료의 개발은 리튬 전지, 슈퍼 축전지, 전력 공급을 포함하는 에너지 저장 매체의 연구에 중심이 되는 요소이다. 이 가운데 금속황화물은 독특하고 우수한 특성 때문에 차세대 전극 재료로서 상당히 주목을 받고 있는 재료이다. 하지만 실제 응용 측면에 있어서 충 방전 관련된 속도와 안정성의 한계가 가장 큰 장애 요소이다. 이러한 한계를 극복하고자 나노구조화에 대한 연구가 집중적으로 진행되고 있다. 본 논문에서는 금속황화물의 에너지 저장 매체로서의 연구 내용을 기술하였다.

• Carbon letters
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• v.7 no.4
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• pp.277-281
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• 2006

In this study, in order to easily provide functional groups on the surface of carbon nanotubes, dual structural multiwalled carbon nanotubes which have crystalline graphite and turbostratic carbon wall were synthesized by modified vertical thermal decomposition method. Synthesized dual structural MWCNTs were characterized by FE-SEM, TGA, HR-TEM, Raman spectroscopy and BET specific surface area analyzer. The average innermost and outermost diameters of the synthesized nanotubes were around 45 and 75 nm, respectively. The large empty inner space and the presence of graphitic carbons on the surface may open potential applications for gas storage and collection of hazardous materials.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1395-1397
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• 1996

Many of the existing neural associative memories are trained and recalled in separate modes and are not suitable for temporal pattern storage and classification in that user must specify the time and length of input patterns. In this paper, a new on-line temporal associative memory model is presented. This memory is structured in layers of neurons and each neuron has limited number of weights so that calculation complexity can be considerably reduced and processing of patterns can be achieved in real time.

• Journal of Internet Computing and Services
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• v.13 no.4
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• pp.83-93
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• 2012

HTML5 has developed not to have browser dependancy considering interoperability as same as maintaining compatability with lower versions of HTML. HTML5, the newest web standardization is on going of being structured. Along with the smart phone boom, HTML5 is spotlighted because it can be applied to cross platforms in mobile web environments. Specially the local Storage that has been listed in new features in HTML5 supports offline function for web application that enables web application to be run even when the mobile is not connected to 3G or wifi. With Local storage, development of server-independent web application can be possible. However Local storage stores plaintext data in it without applying any security measure and this makes the plaintext data dangerous to security threats that are already exist in other client side storages like Cookie. In the paper we propose secure Local storage methods to offer a safe way to store and retrieve data in Local storage guaranteeing its performance. Suggested functions in this paper follow localStorage standard API and use a module that provide cryptographic function. We also prove the efficiency of suggested secure Local storage based on its performance evaluation with implementation.

• Fisheries and Aquatic Sciences
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• v.23 no.9
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• pp.25.1-25.9
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• 2020

Fish is an extremely perishable food product which requires proper handling soon after harvest. The present study was aimed at assessing post-harvest fish losses and preservation practices in Siavonga district, Southern Zambia. Structured and semi-structured questionnaires were used to collect data on post-harvest fish losses and preservation practices from aquaculture producers, artisanal, and commercial fishers. All the fishers who landed on the lakeshore were interviewed, while aquaculture producers were randomly selected based on the information provided by the local department of fisheries. The results of the study revealed that all the fishers experienced post-harvest fish losses at varying degrees with those losing up to 10% of the total catch being in the majority. In contrast, aquaculture producers did not report any post-harvest fish losses. Most aquaculture producers commonly used chilling as preservation practice contrary to artisanal and commercial fishers who commonly used smoking and sun sun-drying respectively. Furthermore, fish product safety and quality control were poorly practiced in the district. Lack of cold storage facilities and fluctuating weather conditions were the major challenges impacting fish post-harvest activities. Therefore, to curb the loss of revenue due to post-harvest fish losses, we propose the introduction of new technology, self-development skills for fishing communities, and enhanced access to refrigeration facilities.

• Journal of Internet Computing and Services
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• v.7 no.5
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• pp.71-79
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• 2006

The GNUnet proposed a file encoding method by lKB block size to support anonymity of files and decentralizes encoded block to peers through unstructured model. but, the encoding and block decentralizing method with 600$\sim$700MB large multimedia file appeared two problems. First problem. it need addition R block and I block, which make about 4% of storage resource. Second problem, unstructured model added network load by broadcasting decentralizing method. This paper suggest variable encoding block size and structured model by block decentralizing solution. Suggested encoding method reduced block request supplementary block generation to 1% and network load by proposal structured model sending answer through dedicated peer to decentralize block.

• Journal of KIISE:Databases
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• v.34 no.5
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• pp.465-472
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• 2007

With the recent proliferation of the use of semi-structured data such as XML, it becomes more important to efficiently store and manage the semi-structured data. The XML data can be logically modelled as a rooted tree e.g., the DOM tree. In order to process a query on the XML data, we traverse the tree structure. In this paper we present an algorithm that places the XML data to disk blocks. The proposed algorithm assigns a number to each node of the tree in a bottom-up fashion. Then, the nodes are allocated to disk blocks using the assigned number. The proposed algorithm does not need access pattern information, and provides good performance for any access pattern. The characteristics of the proposed method are presented with analysis. Through experiments, we evaluate the performance of the proposed method.

• Journal of Intelligence and Information Systems
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• v.10 no.3
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• pp.27-37
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• 2004

XML has been proposed as a document standard for the representation and exchange of data on the WWW, and also becoming a standard for the search and reuse of scattered documents. When implementing a XML contents management system, special consideration should be imposed on how to model data and how to store the modelled data for effective and efficient management of the semi-structured data. In this paper, we proposed a new data model for the storage and search of XML document data. This proposed data model could represent both of data and structure views of XML documents, and be applied to the new data system for XML documents as well as the existing data systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1184-1187
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• 2003

Electrochemical capacitors are becoming attractive energy storage systems particularly for applications involving high power requirements such as hybrid systems consisting of batteries and electrochemical capacitors for electric vehicle propulsion. A new type electric double layer capacitor (EDLC) was constructed by using carbon nanofibers (CNFs) and DAAQ(1,5-diaminoanthraquinone) electrode. Carbonaceous materials are found in variety forms such as graphite, diamond, carbon fibers etc. While all the carbon nanofibers include impurities such as amorphous carbon, nanoparticles, catalytic metals and incompletely grown carbons. We have eliminated of Ni particles and some carbonaceous particles in nitric acid. Nitric acid treated CNFs could be covered with very thin DAAQ oligomer from the results of CV and TG analyses and SEM images. DAAQ oligomer film exhibited a specific capacity as 45-50 Ah/kg in 4M $H_2SO_4$. We established Process Parameters of the technique for the formation of nano-structured materials. Furthermore, improved the capacitive properties of the nano structured CNFs electrodes using controlled solution chemistry. As a result, CNFs coated by DAAQ composite electrode showed relatively good electrochemical behaviors in acidic electrolyte system with respect to specific capacity and scan rate dependency.