• Journal of Korean Society of Transportation
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• v.30 no.4
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• pp.71-81
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• 2012

The Korean government has actively accepted private investments in building expressways to improve its financial status. As of 2012, 422km of 9 private expressways are under operation, and until 2016 additional 15 are planned to be built with private investments. However, on average, each private expressway is at most 37km long, which works against economies of scale in maintenance and thus leads to inefficiencies such as traffic jams, driver inconveniences, and the increase in operating costs. To resolve these problems, the present study suggested that the maintenance and tolling system should be unified across each private operator. Unifying the operation of private expressways was expected to reduce user travel times and tolls, and save operator maintenance costs. These economic effects were expected to be tantamount to hundreds of billions of dollars. The shared toll collecting system will also reduce user's delays by removing main line tollgates. This can save another hundreds of billions of dollars by ensuring driver's convenience and safety.

• Journal of Chest Surgery
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• v.39 no.8 s.265
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• pp.655-658
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• 2006

Mesothelial cyst is a rare mediastinal tumor and usually presents in the right cardiophrenic angle. However, it sometimes occurs in atypical locations and it’s locating in the posterior mediastinum, especially, is very rare. A large cystic mass of the posterior mediastinum between pericardium and vertebral body was incidentally recognized in a patient of a 30-year-old woman admitted due to traffic accident. Even though it was very large in size measuring 18 em at longest diameter and is extending mainly to the left pleural cavity, she had no symptomatic complaints. Complete excision was performed through video-assisted thoracoscopic surgery with a additional small working window, which was necessary for dissecting the deepest point to the right pleural cavity. She is in good condition without recurrence on long-term follow-up.

• Archives of design research
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• v.16 no.2
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• pp.209-218
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• 2003

The increase of wheelchair users due to the rapid growth of elderly population, traffic accidents, and industrial disaster etc. becomes a major issue in our society. Thus, the Convenience Promotion Law was enforced to facilitate the use and installation of convenient facilities for the disabled, the elderly and pregnant women. Currently, not only newly built buildings but also roads and parks are accessed and used by all the people without any hindrance. In contrast to this, so far not many studies on residential space design for wheelchair users have been carried out except for public facilities. So, wheelchair users have to bear the inconvenience in their houses made upon the standards of the general people. Therefore, it is necessary to develop design guideline considering the physical characteristics of wheelchair users and their family members to lead a convenient life. This study was conducted in universal design perspective and intended to establish design guideline of convenient residential space for wheelchair users and general people. To accomplish the objective, surveys for wheelchair users' actual conditions and needs, and video observation were carried out.

• The Journal of the Korea Contents Association
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• v.7 no.10
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• pp.10-18
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• 2007

Today, third-generation(3G) of mobile communication service executing the video and TV. And low cost, high speed data rate will emerge communication of the fourth generation(4G) in future. So, in this paper we studied occupied frequency bandwidth of common technique criteria among the technique criteria for the 4G mobile communication of FDD-based on Up/Down-link. The mobile communication traffic is predicted Up/Down-link of non-symmetric in future. So we proposed the PHY layer parameters of occupied frequency bandwidth of Up/Down-link with both 1:3 and 1:6. We also verified this through the simulation. We proposed the occupied frequency bandwidth for the 4G mobile communication in this paper.

• Journal of Advanced Navigation Technology
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• v.18 no.3
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• pp.209-214
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• 2014

Current black boxes have a problem of storing unnecessary imagery data recordings without data classification. For this reason, users have to erase videos every time. This method is inadequate for black boxes with limited memory capacity. In this paper, we design and implement a system that recognizes traffic accident situations and saves these recordings by classifying them according to weighted values. The system was made to save video recorded at a 30-sec interval of every event to black box folders by changing names based on weighted value data under the external environment in a 1:10 scale model car. Based on this, when the tests were performed as a major car accident while driving, the videos were created in w2 folder, and when the tests were performed as a minor car accident while stopped, the videos were created in w1 folder.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11a
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• pp.201-204
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• 2003

At a consequence of WWW large popularity, the internet has suffered from various performance problems, such as network congestion and overloaded servers. These days, it is not uncommon to find servers refusing connections because they are overloaded. Web server performance has always been a key issue in the design and operation of on-line systems. With regard to Internet, performance is also critical, because users want fast and easy access to all objects (e.g., documents, graphics, audio, and video) available on the net. To solve this problem, a number of companies are exploring the benefits of having multiple geographically or locally distributed Internet sites. This requires a comprehensive scheme for traffic management, which includes the principle of an optimal load balancing of client requests across multiple clusters of real servers. This paper focuses on the performance analysis of Web server and we apply these results to load balancing in clustering web server. It also discusses the mam steps needed to carry out a WWW performance analysis effort and shows relations between the workload characteristics and system resource usage. Also, we will introduce an optimal load balancing algorithm base on the RTSM (Real-Time Server Monitor) and Fuzzy Inference Engine for the local status of a real server, and the benefits is provided with of the suggested method.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.440-443
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• 2001

As inter-network traffics grows rapidly, the router systems as a network component becomes to be capable of not only wire-speed packet processing but also plentiful programmability for quality services. A network processor technology is widely used to achieve such capabilities in the high-end router. Although providing two such capabilities, the network processor can't support a deep packet processing at nominal wire-speed. Considering QoS may result in performance degradation of processing packet. In order to achieve foster processing, one chipset of network processor is occasionally not enough. Using more than one urges to consider a problem that is, for instance, an out-of-order delivery of packets. This problem can be serious in some applications such as voice over IP and video services, which assume that packets arrive in order. It is required to develop an effective packet processing mechanism leer using more than one network processors in parallel in one linecard unit of the router system. Simulation analysis is also needed for verifying the mechanism. We propose the packet processing mechanism consisting of more than two NPs in parallel. In this mechanism, we use a load-balancing algorithm that distributes the packet traffic load evenly and keeps the sequence, and then verify the algorithm with simulation analysis. As a simulation tool, we use DEVSim++, which is a DEVS formalism-based hierarchical discrete-event simulation environment developed by KAIST. In this paper, we are going to show not only applicability of the DEVS formalism to hardware modeling and simulation but also predictability of performance of the load balancer when implemented with FPGA.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.40-49
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• 2015

PicoCast is a recently proposed short-range wireless communications technology that supports both low rate sensor/control data and high speed data such as voice and video traffic in the personal space, defined by the user-centric space of radius tens of meters, with one unified protocol. When the users are in the same area, personal spaces defined by each user may overlap. Since these PicoCast piconets may simultaneously operate, mutual interference is unavoidable. It is necessary to investigate the effect of mutual interference on data transmission and to conduct research on minimizing the interference among PicoCast devices. In this paper we analyze the effect of mutual interference between PicoCast piconets based on data throughput using OPNET network simulator. We have implemented the PicoCast protocol and measured the average throughput and packet loss rate.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.3
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• pp.96-102
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• 2013

In recent years, a variety of ITS services are available such as driving information, road conditions, V2X messages as well as navigation and traffic jams notification. The development of ITS services is accelerating by V2X communication technologies for high-speed vehicles. In this paper, WAVE communication devices based on the IEEE802.11p standard is introduced as a solution of V2X communication technologies. The H/W and S/W structures of the WAVE communication device and the characteristics of RF/antenna are described. The performance is evaluated in the test road by measuring throughput, PER and latency. The implemented WAVE communication device has 6~7 Mbps throughput with 10% PER at 1km coverage. The packet latency is less than 3ms for the whole test road. It is shown that the implemented WAVE technology is satisfactory to provide ITS services and Internet video-streaming services.

• Journal of Digital Contents Society
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• v.3 no.1
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• pp.47-57
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• 2002

Recently, wireless networks have been pursuing multimedia data service as voice, data, image, video and various form of data according to development of information communication technology. It guarantees cell delivery delay of real time data in efficient real time multimedia data transfer. Also, it minimizes cell loss rate of non-real time multimedia data. In the wireless ATM, there are based on Asynchronous Transfer Mode(ATM). It implies that there are various service with difficult transmission rates and qualities in the wireless communication network. As a result, it is important to find out the ways to guarantee the Quality of Service(QoS) for each kind of traffic in wireless network. In this thesis, we propose an improved TCRM scheduling algorithms for transmission real-time multimedia data service in wireless ATM Networks. We appear real time multimedia scheduling policy that apply each different method to uplink and downlik to wireless ATM network. It can guarantee QoS requirements for each real time data and non-real time data. It also deals the fairness problem for sharing the scarce wireless resources. We solve fault of TCRM as inefficient problem of non-real data by using arbitrary transmission speed and RB(Reservation Buffer) through VC(Virtual Control) and BS(Base Station).