• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.312-313
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• 2017

Internet of Things(IoT) is an intelligent technology and service in which all objects communicate with each other through various networks. Recently Internet of Things(IoT) is one of the fields that is attracting attention as the development of ICT industry. MQTT is a protocol which is safe using TLS or adopting light packet structure for effciency of memory and power using. In this paper, when TLS is used the process of encryption / decryption in the broker occurs. We propose an efficient MQTT protocol through centralized key management by adding authentication server.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.85-86
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• 2019

Recently, the educational facilities were 45% among total damaged facilities from the Po-Hang earthquake. Consequently, the seismic reinforcement of existing educational facilities were ended up attracting people's interesting. However, research is insufficient to consider that how far technology has been developed. Therefore, the purpose of this study is to investigate the level of domestic guideline research by comparing to foreign guidelines in regard to seismic reinforcement methods applicable to existing educational facilities. To achieve the objective, first, the current status of seismic reinforcement projects in domestic educational facilities was analyzed. Second, the domestic and foreign seismic reinforcement methods guidelines for structural, non-structural was compared. Third, the improvement directions for future guidelines were suggested. As a results, the improvement directions of domestic seismic reinforcement methods guidelines were proposed. First, the structural seismic reinforcement strategy needs to be segmented. Second, it is necessary to analyze about non-structural guidelines based on additional cases. In the future, this study can be used as a basic material for developing seismic reinforcement methods guidelines in domestic existing educational facilities.

• Transactions on Electrical and Electronic Materials
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• v.12 no.4
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• pp.160-163
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• 2011

Polymer nanocomposite has been attracting more attention as a new insulation material because homogeneous dispersion of nano-sized inorganic fillers can improve various properties significantly. In this paper, various kinds of epoxy-based nanocomposites were made, and the AC breakdown strengths of Nano filler and micro-$SiO_2$ filler mixtures of epoxy-based composites were analyzed using sphere-to-sphere electrodes. Moreover, nano- and microfiller combinations were investigated as an approach to practical application of nanocomposite insulation materials. Its composition ratio was 100 (resin):82 (hardener):1.5 (accelerator). AC breakdown tests were performed at room temperature ($25^{\circ}C$), $80^{\circ}C$, and $100^{\circ}C$ in the vicinity of $T_g$ ($90^{\circ}C$). Thermal conductivity was measured using TC-30.

• Journal of the Korea Society of Computer and Information
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• v.23 no.10
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• pp.65-72
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• 2018

In this paper, we used LSTM as a method to detect abnormal behavior of motors. We fixed the high layout size to 1 and changed the range of the input values and the neural network structure to see what change in power consumption prediction. Now, as the fourth industrial revolution era, smart factories are attracting attention. All the physical actions of smart factories are done using motors. Continuous monitoring of motor malfunctions helps to detect malfunctions and efficient operation. However, it is difficult to acquire the power consumption constantly due to the influence of the noise. We have experimented with a simple experimental environment, a method of predicting similarity to input data by adjusting the range of the input data or by changing the neural network structure.

• Journal of Ship and Ocean Technology
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• v.12 no.1
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• pp.35-44
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• 2008

As arctic energy resource is attracting public attention, arctic shipping market will also be growing in large as expected to increase in LNG trade from Arctic area to the western countries by shipping. During the voyages through such routes, collision with icebergs may be possible. In the present report, ice collision analyses are carried out from a practical point of view to verify the safety of hull structural strength of LNG carriers equipped with GTT $MKIII^{TM}$ membrane type cargo containment system. From the results of collision analyses and the operation-friendly design concept of no-repairing of cargo containment system, a safe operating envelope against ice collision is proposed for LNG carriers of membrane type cargo containment system. Based on the currently proposed safety criteria, it is concluded that LNG carriers with membrane tank type can operate safely with regard to the integrity of CCS in regions where collision between LNG carrier and iceberg is expected.

• Journal of IKEEE
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• v.19 no.2
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• pp.276-281
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• 2015

Engineers increasingly rely on computers and their computer programming skills for their works. As a result, most engineering curricula have introduced a computer programming courses. However, students consider the subject to be unrelated to their core interests and often feel uncomfortable when learning to program for the first time. To overcome these difficulties, several studies have proposed the use of physical computing paradigm. This paradigm takes the computational concepts out of the PC screen and into the real world so that the student can interact with them. This paper proposes Arduino platform as a tool for attracting interest of the programming and reports the results of questionnaire survey analysis.

• The Journal of Korean Association of Computer Education
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• v.5 no.1
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• pp.45-55
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• 2002

So far, there were a few web-based distance English learning systems for children. The existing systems for children have not appropriately reflected their learning characteristics and interests, since most of those systems regards mainly adults as targets. This thesis is aimed at proposing more effective educational service modules of web-based real-time system in order to encourage children's interests as much as possible in learning English. The web-based real-time distance learning system is a model based on the survey over the current use and satisfaction status of elementary school students who have actually used those kinds of systems. With the great expectation of more effective way of learning English, it also focuses on attracting parents to participate the learning process by providing a service to look over, in real-time, what their children do through the internet-based English learning system.

• The Research Journal of the Costume Culture
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• v.20 no.3
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• pp.295-308
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• 2012

This study intends to analyze the up-cycling trend that is attracting great attention these days and its internal meaning in the context of fashion art. And, based on this, to provide enhanced value and creativity in the future fashion artwork and design businesses, keeping abreast of further fashion art developments. As part of the study methodology, both a literature review and a case study were carried out, along with an examination of up-cycling and research into related pictures and content. The materials covered in this work include design and fashion related books and domestic and foreign magazines from 2000 to 2011, when the up-cycling movement was initiated as a form of eco-friendly design. For the analysis of fashion art pieces, generic terms included art wear, wearable art wear, and unwearable art. Case review was followed by the works of artists shaping their fashion concept and meaning entirely from abandoned clothes and fabrics, waste materials, and their art collection. Consequently, key elements of the value of up-cycling fashion art are that it is eco-friendly, has a unique identity, and reflects multi-dimensionalism. This research saw the integration of fashion with other variables, artistic attributes, and reuse of resources. This could lead to a new realm where value-addition is formed and extended, thus providing another chance for the fashion industry.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.339-342
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• 2010

Dual throat nozzle(DTN) is recently attracting much attention as a new concept of the thrust vectoring technique of propulsion jet. This DTN is designed with two throats, an upstream minimum and a downstream minimum at the nozzle exit, with a cavity in between the upstream throat and exit. In the present study, a computational work has been carried out to analyze the performance of a dual throat nozzle(DTN) at various mass flow rate of secondary flow. Two-dimensional, steady, compressible Navier-Stokes equations were solved using a fully implicit finite volume scheme. The present computational results were validated with some experimental data available. Based upon the present results, Thrust-vector control using a DTN is discussed in terms of the thrust coefficient and the coefficient of discharge.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.406-408
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• 2017

Ammonium dinitramide (ADN) Low toxicity monopropellant based 1N class thruster and test equipment were developed. Compared with the hydrazine which used in existing satellite thruster, ADN is easy to handle and has excellent physical characteristics such as density and specific impulse. Due to these characteristics, ADN is attracting attention as an eco-friendly propellant. In this paper, 1N class thruster and thrust measurement system was designed for performance testing of ADN monopropellant. The composition of the propellant for the design and experiment was set at 11.2: 25.4: 63.4 for each of Methanol: $H_2O$: ADN.