• Journal of the Korea Society for Simulation
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• v.24 no.1
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• pp.17-24
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• 2015

Smart grid is a modernized electrical grid that uses information and communication technologies to gather and act on information, such as information about the behaviors of suppliers and consumers, in an automated fashion to improve the efficiency, reliability, economics, and sustainability of the production and distribution of electricity. However, with the advent of cyber crime, there are also concerns on the security of the infrastructure, primarily that involving communications technologies. In this work, we make an in-depth investigation on the issue of security services and network loads on Smart grid. Through simulation, we analyze the relations between security services and network loads. The experimental results of this study will contribute toward designing an advanced Smart grid system that offers better quality of services. Also, the approach proposed in this study can be utilized to derive new and valuable insights in security aspects.

• Journal of the Korea Society for Simulation
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• v.16 no.3
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• pp.49-56
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• 2007

There are many application areas of wireless sensor networks, such as combat field surveillance, terrorist tracking and highway traffic monitoring. These applications collect sensed data from sensor nodes to monitor events in the territory of interest. One of the important issues in these applications is the existence of the radio-jamming zone between source nodes and the base station. Depending on the routing protocol the transmission of the sensed data may not be delivered to the base station. To solve this problem we propose a genetic algorithm based routing method for reliable transmission while considering the balanced energy depletion of the sensor nodes. The genetic algorithm finds an efficient routing path by considering the radio-jamming zone, energy consumption needed fur data transmission and average remaining energy level. The fitness function employed in genetic algorithm is implemented by applying the fuzzy logic. In simulation, our proposed method is compared with LEACH and Hierarchical PEGASIS. The simulation results show that the proposed method is efficient in both the energy consumption and success ratio of delivery.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.27-36
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• 2018

In this paper, we design and implement a real time IoT messaging system that can collect location information of moving vehicles and pedestrians in real time using MQTT protocol and provides location based information service in administrative area. We implemented MQTT based IoT device for vehicle location information collection and communication and MQTT based smartphone application for pedestrian location information service. IoT clients can send messages to the server in administrative units by using the MQTT Topic which is equal to administrative names. The SLIMS (Seoul Location based IoT Messaging System) implemented in this study is able to analyze the real time traffic volume of pedestrians and vehicles by tracking clients. It also can deliver messages to clients based on coordinate range. SLIMS can be used as a real-time location-based information service for large-scale IoT devices such as real-time flow population and vehicle traffic analysis and location-based message delivery.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.6
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• pp.9-17
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• 2012

High-quality multimedia on the Internet has attracted attention because of its wide application area. IP multicast has been proposed as a solution to use efficient network resources in these services. However, IP multicast has not been commonly used due to a number of practical issues such as security and management. As an alternative, an overlay multicast routing which is performed in upper protocol layers on legacy networks without changing hardware has been presented. Yet, the maximum data transmission capacity of the overlay multicast is not sufficient for real time transmission of multimedia data. In this paper, we have implemented an overlay multicast engine on NetFPGA which allows us to perform packet replication and tunneling which need high-speed. In addition, we have implemented extra portions which need low-speed in software. From now on, we will progress research which increase the number of terminal spots which can be replicated by improvement and amplify throughputs by optimization.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.4 s.316
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• pp.79-88
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• 2007

Demand for the technology for access to device control network in industry and for access to building automation system via internet is on the increase. In such technology integration of a device control network with a data network such as internet and organizing wide-ranging DCS(distributed control system) is needed, and it can be realized in the framework of VDN(virtual device network)[1,2]. Specifications for device control network and data network are quite different because of the differences in application. So a router that translates the communication protocol between device control network and data network and efficiently transmits information to destination is needed for implementation of the VDN, This paper proposes the concept of NCS(networked control system) based on VDN(virtual device network) and suggests the routing algorithm that uses embedded system.[3]

• Journal of Ecology and Environment
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• v.30 no.3
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• pp.271-276
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• 2007

A simple and efficient protocol was developed for culturing Cu-tolerant and Cu-accumulating plants via pre-adaptation to Cu during plant tissue culture. We induced multiple shoots from begonia (Begonia evansiana Andr.) leaf explants on MS medium supplemented with naphtaieneacetic acid and benzyladenine. After 3 months, small plantlets were transferred to MS medium supplemented with $100{\mu}M\;CuCl_2$ for pre-adaptation to Cu and cultured for 5 months. Then, these plantlets were individually planted in pots containing artificial soil. An additional 500 mg of Cu dissolved in 1/4 strength MS solution was applied to each pot during irrigation over the course of 2 months. We planted pre-adapted and control begonias in soil from the II-Kwang Mine, an abandoned Cu mine in Pusan, Korea, to examine their ability to tolerate and accumulate Cu for phytore-mediation. Pre-adapted begonias accumulated $1,200{\mu}g$ Cu/g dry root tissue over the course of 45 days. On the other hand, non-Cu-adapted controls accumulated only $85{\mu}g$ Cu/g dry root tissue. To enhance Cu extraction, chelating agents, ethylenediamine tetraacetic acid (EDTA)-dipotassiun and pyridine-2,6-dicarboxylic acid (PDA), were applied. While the chelating agents did not enhance accumulation of Cu in the roots of control begonias, EDTA application increased the level of Cu in the roots of pre-adapted begonias twofold (to $2,500{\mu}g$ Cu/g dry root tissue). Because pre-adapted begonias accumulated a large amount of Cu, mainly in their roots, they could be used for phytostabilization of Cu-contaminated soils. In addition, as a flowering plant, begonias can be used to create aesthetically pleasing remediation sites.

• Journal of Electrochemical Science and Technology
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• v.1 no.2
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• pp.102-111
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• 2010

Molten carbonate fuel cell (MCFC) power plants are one of most attractive electricity generation systems for the use of biogas to generate high-efficiency ultra-clean power. However, MCFCs are considerably more expensive than comparable conventional electricity generation systems. The commercialization of MCFCs has been delayed more than expected. After being effective in the Kyoto protocol and considerably increasing the fossil price, the attention focused on $CO_2$ regression and renewable energy sources has increased dramatically. In particular, the commercialization and application of MCFC systems fed with biogas have been revived because of the characteristics of $CO_2$ collection and fuel variety of MCFCs. Better economic results of MCFC systems fed with biogas are expected because biogas is a relatively inexpensive fuel compared to liquefied natural gas (LNG). However, the pretreatment cost is added when using anaerobic digester gas (ADG), one of the biogases, as a fuel of MCFC systems because it contains high $H_2S$ and other contaminants, which are harmful sources to the MCFC stack in ADG. Thus, an accurate economic analysis and comparison between MCFCs fed with biogas and LNG are very necessary before the installation of an MCFC system fed with biogas in a plant. In this paper, the economic analysis of an MCFC fed with ADG was carried out for various conditions of electricity and fuel price and compared with the case of an MCFC fed with LNG.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.2
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• pp.197-202
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• 2015

Numerous challenges in treating permanent dentition are encountered, especially in treating immature teeth with pulp necrosis. Historically, calcium hydroxide application during long periods of time was used to induce the formation of a calcific barrier across the open apex. In 2004, a new treatment modality for the management of the open apex was introduced. This treatment was named as 'revascularization' and gained acceptance among dentists. The protocol was different from the traditional apexification techniques in that the canal was irrigated and disinfected with a combination of three antibiotics (ciprofloxacin, metronidazole and minocycline). At the next appointment, bleeding was induced and the canal was sealed with MTA. Successful regenerative endodontic treatment of necrotic immature permanent teeth can provide continued root development, increased thickness in the dentinal walls and apical closure. These developments of a functional pulp-dentin complex have a promising impact on retaining the natural teeth, the goal of the dental health care.

• The Journal of the Korean dental association
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• v.55 no.11
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• pp.778-788
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• 2017

Ultrasound sonography(US) is used to evaluate various diseases of oral and maxillofacial region including salivary glands, soft tissue and jaw lesions because of easy accessibility and no hazard of ionizing radiation. Also, US can offer dynamic study showing real-time images during diagnostic or surgical procedure. US images provide accurate information about the internal features of lesions on the jaw prior to surgical treatment. Doppler images are used to visualize the vascular distribution of the lesions and to provide additional information to enhance diagnostic value. It is necessary to evaluate the diagnostic value of US and evaluate its usefulness by looking at clinical cases using US images. Therefore, US imaging may be recommended as an assistant image in evaluating jaw lesions. US images provided accurate information about the internal structure of lesions on the jaw prior to surgical treatment, and diagnostic value was enhanced by visualizing the vascular distribution of the lesion using doppler imaging. We report the protocol and suggest the effectiveness of US for various lesions and US-guided sialography.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.2
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• pp.164-170
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• 2005

The purpose of this study was to compare a sample of patients who had condylar fractures treated with open reduction using different plating techniques, to evaluate which plating technique is useful for stable fixation for fractures of the mandibular condyle and to evaluate effectiveness of resorbable miniplate. There were 60 patients (41 males, 19 females) whose condylar fractures were treated with open reduction. Rigid fixation was performed with a single miniplate, double miniplate ot one miniplate & one microplate and single resorbable plate. All patients remained intermaxillary fixation for 1 week postoperatively. Active physiotherapy was started after 2 weeks postoperatively. Radiographic evaluation (plate fracture, plate bending, screw loosening, displacement of condyle etc.) was performed at pre-operative, immediate, 2 weeks, 1 month, 3 months, 6 months after surgery. Clinical evaluation included degree of mouth opening, occlusion, mandibular lateral excursion, infection and facial nerve paralysis. In radiographic evaluation, displacement of fractured condylar segment associated with plate bending or screw loosening were showed 6 cases and 3 cases for single miniplate system and resorbable miniplate system. There was no patients who have this problem on double miniplate system. The results revealed that the application of two miniplates were more recommendable than single miniplates. When we select resorbable miniplate system, we should consider the type of fractures, post-operative treatment protocol and surgical technique.