• Journal of Advanced Navigation Technology
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• v.21 no.2
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• pp.200-205
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• 2017

Modern sports are developing into sports science that incorporates science and various analytical simulation systems for improving records are being developed, and they are helping to improve actual game records. Therefore golf which is one of various sports events, has been popularized among the hobbyists and the general public and there is an increasing demand for correcting the movement attitude of the person. In response to these demands, many systems have been developed to analyze and correct golf swing postures. The golf swing accuracy analysis system analyzes the moments that can not be seen with the naked eye and guides them to understand easily. It can improve the golf swing motion through immediate feedback due to the visual effect. Using the knowledge of golf swing motion collected from golf swing video, we improved reliability. In addition, it provides the ability to visually check and analyze your golf swing video, allowing you to analyze each segment based on various golf swing classification methods.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.7
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• pp.1056-1063
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• 2015

In this paper, we develop an interface for aerial photograph platform which consists of a quadrotor and a gimbal using the human body and the head posture. As quadrotors have been widely adopted in many industries such as aerial photography, remote surveillance, and maintenance of infrastructures, the demand of aerial video and photograph has been increasing remarkably. Stick type remote controllers are widely used to control a quadrotor, but this method is not an intuitive way of controlling the aerial vehicle and the camera simultaneously. Therefore, a new interface which controls the serial photograph platform is presented. The presented interface uses the human head movement measured by head-mounted display as a reference for controlling the camera angle, and the human body posture measured from Kinect for controlling the attitude of the quadrotor. As the image captured by the camera is displayed on the head-mounted display simultaneously, the user can feel flying experience and intuitively control the quadrotor and the camera. Finally, the performance of the developed system shown to verify the effectiveness and superiority of the presented interface.

• Education of Primary School Mathematics
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• v.18 no.2
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• pp.61-75
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• 2015

This study analyzed the characteristics of mathematical tasks including the level of cognitive demands set up by pre-service elementary school teachers. 50 pre-service teachers in G university of education who participated in their 4 weeks teaching practicum were selected as subjects. They planned and implemented mathematics lesson with their lesson plans. Lesson plans, video of their lessons, transcript of video were gathered and analyzed the characteristics of mathematical tasks used in their lesson. Through the analysis, several conclusions were drawn as follow. First, 78% of the subjects modified tasks in mathematics textbooks. Since modification or construction of mathematical tasks gives good chance for constructing mathematical task knowledge for teaching, more chance should be given to pre-service teachers to construct new tasks or modify tasks in mathematics textbooks. Second, types of modification done by pre-service teachers were categorized as number change(15.6%), situation change(78.1%) and material change(6.3%). As Chapman(2013) emphasized the importance of MtKT, pre-service teachers must have more MtKT by understanding the characteristics of mathematical tasks. Third, the level of cognitive demands required by mathematical tasks were relatively low. 74% of mathematical tasks was lower cognitive demands and only 26% was higher cognitive demands. The level of cognitive demands of tasks in mathematics textbooks tended to be lowered by the directions given right after the tasks were given. In this respect, the structure of mathematics textbooks need to be changed.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2
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• pp.337-346
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• 2000

In a Vod(video0on-demand) system, a scheduling strategy is designed to increase the system efficiency and to eatisfy the isochronous requirements of showing a video to multiple viewers with one disk access. In this paper, we have proposed the Stream Relay Scheme (SRS) which utilizes the client's buffer space to reduce the server's disk I/O, buffer consumption, and stream capacity. Under the SRS which we have proposed in this paper, the server does not service all the requests directly but forwards the new request selectively to the client who is being served currently in order to reduce the initial latency and increase the system throughput. The SRS-BAT which integrated the SRS with the Batching technique is introduced. The results of the simulated experiments which compared the SRS with the conventional technique have shown the noticeable performance improvements in terms of initial latency and the server throughput.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.287-292
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• 2001

Multimedia service systems should have efficient capacity to serve the growing clients and new data. In the general streaming services, users can endure the small amount of time delay at the beginning of service. But they want to have good quality of service. A streaming server tries to transfer video files to clients from a repository of files in real time. The server must guarantee concurrent and uninterrupted delivery of each video stream requested from clients. To achieve its purpose, many stream servers adopt multi-processors, sufficient memory, and RAID or SAN in their systems. In this paper, we propose a Linux-based parallel media streaming server. It is superior to the other systems in the storing structure, fault-tolerance, and service capacity. Since this system supports the web interlace, users can operate easily through the www. This system uses unique striping policy to distribute multimedia files into the parallel storage nodes. If a service request occurs, each storage node transmits striped files concurrently to the client. Its performance is better than the single media streaming service because of the parallel architecture.

• Journal of Korea Game Society
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• v.16 no.2
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• pp.61-74
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• 2016

As e-Sports evolves, a variety of industries grow together. Game broadcastings contribute to spread video game culture through various media platforms. Hence people start to perceive e-sports as a genre of sports and the demand on real-time game broadcasting increases. The global game broadcasting channels based on OTT(Over-The-Top) service also increase rapidly. In this paper we understand the status of streaming service and watching attitude of global game broadcasting. We also provide practical suggestions along with analysis results.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.3
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• pp.315-322
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• 2018

Due to the increasing demand for more rapid, precise and accurate geolocation of the targets on video frames from UAVs, an efficient and timely method for correcting sensor models of motion imagery is required. In this paper, we propose a method to adjust or correct sensor models of motion imagery frames using space resection via image matching with reference data. The proposed method adopts image matching between the motion imagery frames and the reference frames which are synthesized from reference data. Ground or reference control points are generated or selected through the matching process in near real time, and are used for space resection to get adjusted sensor models. Finally, more precise and accurate geolocation of the targets can possibly be done on the fly, and we have got the promising result on performance analysis in terms of the geolocation quality.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.1
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• pp.47-53
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• 2014

LTE-Advanced is the evolved version of LTE which is currently in progress at the 3GPP. At present, as the number of smart phone users is rapidly increasing, the demand for ever more capacity is driven largely by video usage and high quality data communication and so on, this let more researchers study about LTE-A all over the world. LTE-A aims to achieve improved service and communication quality over 3G system at the aspect of throughput, peak data rate, latency, and spectral efficiency. Among various features in LTE-A, the multi-user MIMO(MU-MIMO), in which the base station transmits several streams to multiple receivers, has expected to give better quality for system. In this paper, we investigate performances of various types of downlink receivers with fixed number of antennas. we first review the development process from LTE to LTE-A. Second we introduce TM9 which is adopted in Rel.10 for MU-MIMO system, including the MU-MIMO system model and the explanation on the algorithm used in system. We also have brief introduction about sub-blocking in turbo decoding, finally we compare the performance between the uncoded case and coded case which is using turbo encoding.

• ETRI Journal
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• v.35 no.4
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• pp.687-696
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• 2013

The development of proxy caching is essential in the area of video-on-demand (VoD) to meet users' expectations. VoD requires high bandwidth and creates high traffic due to the nature of media. Many researchers have developed proxy caching models to reduce bandwidth consumption and traffic. Proxy caching keeps part of a media object to meet the viewing expectations of users without delay and provides interactive playback. If the caching is done continuously, the entire cache space will be exhausted at one stage. Hence, the proxy server must apply cache replacement policies to replace existing objects and allocate the cache space for the incoming objects. Researchers have developed many cache replacement policies by considering several parameters, such as recency, access frequency, cost of retrieval, and size of the object. In this paper, the Weighted-Rank Cache replacement Policy (WRCP) is proposed. This policy uses such parameters as access frequency, aging, and mean access gap ratio and such functions as size and cost of retrieval. The WRCP applies our previously developed proxy caching model, Hot-Point Proxy, at four levels of replacement, depending on the cache requirement. Simulation results show that the WRCP outperforms our earlier model, the Dual Cache Replacement Policy.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.7
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• pp.744-753
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• 2015

This paper presents the results of research on developing marine unified communications to provide VoIP service based on marine satellites. With the recent popularity of smart-phones and other mobile devices, the demand for Internet-based wired and wireless unified technology has been growing in marine environments, and increasing interest is being directed to VoIP products and service models with high price competitiveness and the ability to deliver a variety of services. In this regard, this research designed three instruments, developed their unit modules, and verified their performances. These three instruments included the following: (1) a marine VoIP module equipped with an analogue gateway that can be linked to the existing devices used in vessels, which is more than 80% smaller than that of a land system; (2) a text/voice/video engine for marine satellite communications that runs on technology that minimizes communication data usage, which is a core technology for a marine VoIP service; and (3) a unified communication service that can support multilateral cloud-based message conversations, telephone number-based call functions, and voice/video calling between a private space in a ship and shore.