• Journal of Korean Association for Spatial Structures
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• v.9 no.4
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• pp.61-72
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• 2009

As a trend of construction has become high-rise and larger, it is necessary to reduce the self-weight of structures and buildings. One of the most effective methods to reduce the self-weight of structures and buildings is to use the lightweight aggregate concrete. To complement the strength of the lightweight aggregate concrete, polymer was added to concrete's mixing. In this study, experiments to make the moderate mixing proportion of polymer modified lightweight concrete were performed. Also the hardened concrete tests were performed to investigate the physical characteristics of the polymer-modified lightweight aggregate concrete. As a result, the flexural strength was increased by a small quantity of SBR Latex. Based on the test results the estimating equation was proposed through the regression analysis.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.6
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• pp.585-591
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• 2015

In transcription for spoken language research, labeling is a work linking text-represented utterance to recorded speech. Most existing labeling tools have been working manually. Semi-automatic labeling we are proposing consists of automation module and manual adjustment module. Automation module extracts voice boundaries utilizing G.Saha's algorithm, and predicts utterance boundaries using the number and length of utterance which established utterance text. For maintaining existing manual tool's accuracy, we provide manual adjustment user interface revising the auto-labeling utterance boundaries. The implemented tool of our semi-automatic algorithm speed up to 27% than existing manual labeling tools.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.8
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• pp.545-552
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• 2017

In this research, numerical analysis was carried out on novel and existing fins, adjusted in terms of factors such as length, spacing, and angle, of a high-temperature heat exchanger for a 1 kW class Stirling engine, designed as a prime mover for a domestic cogeneration system. The performance improvement as a result of shape optimization was confirmed with numerical analysis by including the air preheater, which was not considered during optimization. However, a negative heat flux was observed in the cylinder head portion. This phenomenon was clarified by analyzing the exhaust gas and wall surface temperature of the combustion chamber. Furthermore, assuming an ideal cycle, the effects of heat transfer enhancement on the thermodynamic cycle and system performance were predicted.

• Archives of design research
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• v.17 no.4
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• pp.307-318
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• 2004

We could understand that Woohari oven place is the main place to create important ceramic from Sejongsillokjiriji through the research on the collected remains and books. It was very important founding to understand The history of Korean ceramic industry as well as the special feature of the valuable ceramic in Chosun Dynasty because this place is considered as the original place for center of creating valuable ceramic which called Gongseunghyun during the King, Sejong. Most of the unearthed pieces are containers for living. Specially, it shows clearly about this thought after we found a piece of a soup bowl which has the black letter "Seon". So Woorhar Kiln is an official place to manage food during the King, Sejong(1420') which took care of tribute for one of Sasunsa.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1099-1106
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• 2012

Microgrid is a new electrical energy system that composed of various generators, renewable energy, batteries and loads located near the electrical customers. When Microgrid is interconnected with large power system, Microgrid don't need to control the frequency. But in case of the outage or faults of power system, Microgrid should control the frequency to prevent the shutdown of Microgrid. This paper presents the frequency control methods using the droop function, being used by synchronous generators and EMS(Energy Management System). Using droop function, two battery systems could share the load based on locally measured signals without any communications between batteries. Also, we suggest that EMS should control the controllable distributed generators as P/Q control modes except batteries to overcome the weakness of droop function. Finally we suggest the two batteries systems to prolong the battery's life time considering the economical view. The validation of proposed methods is tested using PSCAD/EMTDC simulations and field test sites at the same time.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.3
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• pp.491-498
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• 2014

Recently, cyber terror has been occurred frequently based on advanced persistent threat(APT) and it is very difficult to detect these attacks because of new malwares which cannot be detected by anti-virus softwares. This paper proposes and verifies the algorithms to detect the advanced persistent threat previously through real-time network monitoring and combinatorial analysis of big data log. In the future, APT attacks can be detected more easily by enhancing these algorithms and adapting big data platform.

• Journal of KIISE:Information Networking
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• v.30 no.6
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• pp.720-728
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• 2003

Blind signature is such a signature scheme that conceals the contents of signature itself and who is the user of the signature make user's anonymity possible. For this reason, they are used in security services such as electronic cashes and electronic votes in which the behavior of actor should not be exposed. In this paper we propose an ID-based blind signature scheme from Gap Diffie-Hellman group. Its security is based on the hardness of Computational Diffie-Hellman Problem. Proposed scheme efficiently improve against existing blind signature scheme by using two-pass protocol between two users and by reducing computation process. Therefore it can be used efficiently in wireless PKI environment.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.12
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• pp.575-583
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• 2001

Dynamic Voltage Restorer(DVR) which is installed between the supply and a critical load can restore voltage disturbances in distribution system. The restoration is based on injecting the same voltages as voltage sags. The ideal restoration is compensation to make the load voltages be unchanged. But voltage restoration involves real power or energy injection and the capability of energy storage is limited. So it must be considered how injection energy can be minimized and voltages can be made close to the voltages before fault. This paper describes conventional restoration techniques, which draw minimum energy from the DVR in order to correct a given voltage sag or swell. And this paper proposes a new concept of restoration technique to inject minimum energy. The proposed method is based on the definition of voltage tolerance in load side. Hence using the proposed method a particular disturbance can be corrected with less amount of storage energy compared to those of conventional methods.

• Annual Conference of KIPS
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• 2006.11a
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• pp.735-738
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• 2006

전자화폐가 안전하게 널리 사용되기 위해서는 여러 가지 특성을 만족해야 한다. 그러한 특성 중에서 데이터의 손실이나 분실에 따른 피해를 막기 위한 복구가능성과 사용자의 전자화폐 사용 내역과 같은 정보를 보호하기 위한 불추적성은 서로 충돌하는 특성으로 동시에 달성하는 것이 매우 어렵다. 기존에 제안된 전자회폐 시스템에서는 이 문제를 해결하는 과정에서 해쉬함수를 사용하였으나, 해쉬함수의 충돌회피성 때문에 실제로 구현하여 사용하는데 문제가 있다. 본 논문에서는 이에 대한 해결 방안을 제시하여 좀 더 효율적으로 구현 가능한 전자화폐 시스템을 제안한다.

• The KIPS Transactions:PartC
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• v.15C no.2
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• pp.125-132
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• 2008

As the development of Internet technology, the number of IDs managed by each individuals has been increased. And many software development institutes have developed ID/PW management solutions to facilitate secure and convenient management of ID/PW. However, these solutions also can be vulnerable in case of administrator's password exposure. Thus, we need to derive security requirements from the vulnerability analysis of these solutions, also we need evaluation criteria for secure ID/PW management solution development. In this paper, we analyze the vulnerability of ID/PW management solution and propose the evaluation criteria for secure ID/PW management solution.