• Journal of Korean Elementary Science Education
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• v.26 no.2
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• pp.226-241
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• 2007

The purpose of this study was to elucidate elementary school teachers' pedagogical content knowledge regarding the subject of "weight and pressure in water". 6 elementary teachers in charge of the 6th grade were selected for this study. The 7 hour lessons were observed over $15{\sim}20$ days, and a variety of data including scenarios, questionnaires for teachers, interviews of teachers were analyzed. As a result of this study, teachers who had long career histories thought that the purpose of teaching science was to teach the use of science principles, and teachers who had only taught for a relatively short time thought the purpose was satisfying students' curiosity. Most of the teachers felt that the science content knowledge related to buoyancy was insufficient. They had acquired most of the science content knowledge from teaming experiences in middle and high schools. The pre-service teacher education programs didn't help them to satisfactorily acquire the science content knowledge under analysis here. Most of the teachers taught the science lessons according to the order of sequence as shown in the science textbook. They didn't teach the contents that they thought were needed if they were not already included in the science textbook. Only one teacher who had taken science courses in high school managed the science classes freely according to his own thoughts and opinions. From the results of this research, it could be concluded that most elementary school teachers did not have enough pedagogical content knowledge to teach their students effectively.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.6
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• pp.1267-1276
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• 2013

Cloud consumers who use cloud computing services are obliged to review and monitor the legal compliance of cloud providers who are consigned the processes of the PII (personally identifiable information) from them. This paper presented possible scenarios for cloud PII outsourcing and suggested PIMS (personal information management system) controls for outsourcing management between cloud consumers and cloud providers by analyzing both international standards and domestic certification schemes related to cloud computing and/or privacy management based on the legal obligations for PII outsourcing from Korean "Personal Information Protection Act (PIPA)". The controls suggested can be applicable for developing the guidance of complying with privacy laws in organizations or the checklist of PII outsourcing management in PIMS certification.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8A
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• pp.1115-1125
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• 1999

This paper forecasts the number of GMPCS(Global Mobile Communications by Satellite) subscribers in Korea. Since GMPCS adopts nor only a new tecnology cor proved in the market yet, bot also a global service principle, it's service market involves a great deal of nucertainties in terms of technological and regulatory perspectives. This paper develops a modified diffusion which considers those uncertainties by identifying three environmental group of tactors. The parameters of the model are estimated through a scenario-based approach. By assuming a pessimistic and an optimistic scenarios with three environmental group of factors, the model forecasts 4,000 and 7,000 substcribers in the first year, and then 100,000 and 600,000 subscribers in 2005 respectively. The sensitivity analysis of the model also gives an implication of the future market growth. In the early period, regulatoyu and technological issues are found to be relatively important, but, in the later period, the interconnection issues and price-competitiveness will become increasingly important.

• Journal of Communications and Networks
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• v.11 no.6
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• pp.574-588
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• 2009

Although much research has been conducted in the area of authentication in wireless networks, vehicular ad-hoc networks (VANETs) pose unique challenges, such as real-time constraints, processing limitations, memory constraints, frequently changing senders, requirements for interoperability with existing standards, extensibility and flexibility for future requirements, etc. No currently proposed technique addresses all of the requirements for message and entity authentication in VANETs. After analyzing the requirements for viable VANET message authentication, we propose a modified version of TESLA, TESLA++, which provides the same computationally efficient broadcast authentication as TESLA with reduced memory requirements. To address the range of needs within VANETs we propose a new hybrid authentication mechanism, VANET authentication using signatures and TESLA++ (VAST), that combines the advantages of ECDSA signatures and TESLA++. Elliptic curve digital signature algorithm (ECDSA) signatures provide fast authentication and non-repudiation, but are computationally expensive. TESLA++ prevents memory and computation-based denial of service attacks. We analyze the security of our mechanism and simulate VAST in realistic highway conditions under varying network and vehicular traffic scenarios. Simulation results show that VAST outperforms either signatures or TESLA on its own. Even under heavy loads VAST is able to authenticate 100% of the received messages within 107ms. VANETs use certificates to achieve entity authentication (i.e., validate senders). To reduce certificate bandwidth usage, we use Hu et al.'s strategy of broadcasting certificates at fixed intervals, independent of the arrival of new entities. We propose a new certificate verification strategy that prevents denial of service attacks while requiring zero additional sender overhead. Our analysis shows that these solutions introduce a small delay, but still allow drivers in a worst case scenario over 3 seconds to respond to a dangerous situation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.125-130
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• 2014

According to the lunching of Google glass, the interest for wearable computer is increasing. This paper is about how to apply humanity or humanist metaphor to the development and application of wearable computer. Humanity is consisted of dream, imagination and desire of human mind. However the software development methodology and application design of engineering part are consisted of the logical language and also they are testable. In this paper the different academics are combined and researched to develop the human-friendly application which are the design of humanities-applying wearable computer and the service scenarios. This paper shows the specific examples of services to search, share and analyze the information with wearable computer also presents what kinds of humanistic metaphor is able to apply in this process.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.7
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• pp.2325-2349
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• 2014

Network virtualization technology plays a key role in cloud computing, which serves as an effective approach for provisioning a flexible and highly adaptable shared substrate network to satisfy the demands of various applications or services. Recently, the problem of mapping a virtual network (VN) onto a substrate network has been addressed by various algorithms. However, these algorithms are typically efficient for unicast service-oriented virtual networks, and generally not applicable to multicast service-oriented virtual networks (MVNs). Furthermore, the survivable MVN mapping (SMVNM) problem that considers the survivability of MVN has not been studied and is also the focus of this work. In this research, we discuss SMVNM problem under regional failures in the substrate network and propose an efficient algorithm for solving this problem. We first propose a framework and formulate the SMVNM problem with the objective of minimizing mapping cost by using mixed integer linear programming. Then we design an efficient heuristic to solve this problem and introduce several optimizations to achieve the better mapping solutions. We validate and evaluate our framework and algorithms by conducting extensive simulations on different realistic networks under various scenarios, and by comparing with existing approaches. Our simulation experiments and results show that our approach outperforms existing solutions.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.4
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• pp.330-335
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• 2011

This paper presents estimation of average compressive strengths of three types of stiffened panels under lateral pressure and axial compression based on simplified formulas from CSRs and nonlinear FEAs. FEA scenarios are prepared based on the slenderness ratios of the stiffened panels used for in-service vessels. The seven step lateral pressures by 1bar increment are imposed on FE models assuming maximum 30m water height. The number of FEAs for FB-, AB-, and TB-stiffened panels is totally 189 times. FEA results show that existence of pressure can evolves significant reduction of ultimate strengths, meanwhile CSR formulas do not take into account the lateral pressure effect. Lateral pressure acting on the stiffened panel with higher column slenderness ratio more reduces the ultimate strengths than those with smaller column slenderness ratio. A new concept of relative average compressive strain energy instead of the ultimate strength is introduced in order to rationally compare the average compressive strength through complete compressive straining regime. The differences of the ultimate strengths between CSR formulas and FEA results are relatively small for FB- and AB-stiffened panels, but larger discrepancies of relative average compressive strain energies are shown.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.2C
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• pp.188-195
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• 2012

Many systems are developing for the realization of NCW(Network Centric Warfare). UAV(Unmanned Aerial Vehicle) Network is attracting attention in a lot of military applications. In general, UAVs have the potential to create an ad-hoc network and greatly reduce the hops from source to destination. However, UAV networks exhibit unique properties such as high mobility, high data rate, and real time service. The routing protocols are required to design the multi-hop routing protocols that can dynamically adapt to the requirements of UAV network. In this paper we analyse Geographic Routing Protocol is based on geographical distance between source and destination for efficient and reliable transmission. Geographic Routing Protocol is evaluated in video service scenarios with TDMA model in our simulation. The simulation results show that the performance of Geographic Routing Protocol is better than the MANET Routing Protocol in terms of packet received ratio, end to end delay, and routing traffic sent.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.5
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• pp.561-569
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• 2016

In this paper a concept of the paradigm shift in the operations of Water and Wastewater systems regarding the production and usage of water was introduced. Based on this concept the interrelationships between the water quality in the upper basin of NakDong River relative to Busan and the degree of satisfaction of the customers on the water supply service in Busan were modeled using the System Dynamics modeling methodology. SamRangJin basin area was determined as the upper basin of Busan after analyzing the relationships between the water quality of MoolGeum water intake point and water quality data of various mid- and upper water intake points along NakDong River. The amount of contaminants generated in SamRangJin basin was modeled using the Gross Regional Domestic Product in the area and the treated amount was calculated using the efficiency of wastewater treatment and the degree of improvement of environmental condition per investment. The water quality at MoolGeum water intake point was modeled to take the effects of the remaining amount of contaminants after treatment and the non-point source contaminants in SamRangJin basin. Using the developed System Dynamics model the effects of the investment for the improvement of environmental condition in SamRangJin basin were compared to the case of alternate water source development for Busan in terms of the degree of satisfaction of the customers on the water supply service in Busan.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.45-46
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• 2015

The guideline on software quality assurance and human-centered design for e-Navigation was approved as IMO circular June 2015. e-Navigation software systems are characterized by a high proportion of data quality and quality in use. The purpose of this paper is to improve the quality in use of the maritime software quality assurance for the safety route guiding service. In this study, we added the stage which the stockholders such as a project manager, software developers, and end-users use the prototype that was developed based on the scenarios before the stage of design and development. Through this, we could review the requirement about the quality in use for a limited time at the beginning of the project. also we could raise understanding the concept of this project and goal system.