• Proceedings of the Korea Information Processing Society Conference
• /
• 2014.11a
• /
• pp.798-801
• /
• 2014

여행 정보 시스템(ATIS), 교통 관리 시스템 (ITS) 등 궤적 기반 서비스에서, 서비스 품질을 향상시키기 위해서는 주어진 궤적 질의에 대한 정확한 주행시간을 예측하는 것이 필수적이다. 이를 위한 대표적인 공간 데이터 분석 기법으로는 데이터 분류에서 높은 정확도를 보장하는 규칙 기반 분류화 기법이 존재한다. 그러나 기존 규칙 기반 분류화 기법은 단일 컴퓨터 환경만을 고려하기 때문에, 대용량 공간 데이터 처리에 적합하지 않은 문제점이 존재한다. 이를 해결하기 위해, 본 연구에서는 맵리듀스 환경에서 규칙 기반 분류화를 이용한 궤적 데이터 주행 시간 예측 알고리즘을 개발하고자 한다. 제안하는 알고리즘은 첫째, 맵리듀스를 이용하여 대용량 공간 데이터를 병렬적으로 분석함으로써, 활용도 높은 궤적 데이터 규칙을 생성한다. 이를 통해 대용량 공간 데이터 기반의 규칙 생성 시간을 감소시킨다. 둘째, 그리드 구조 기반의 지도 데이터 분할을 통해, 사용자 질의처리 시 탐색 성능을 향상시킨다. 즉, 주행 시간 예측을 위한 규칙 그룹을 탐색 시 질의를 포함하는 그리드 셀만을 탐색하기 때문에, 질의처리 성능이 향상된다. 마지막으로 맵리듀스 구조에 적합한 질의처리 알고리즘을 설계하여, 효율적인 병렬 질의처리를 지원한다. 이를 위해 맵 함수에서는 선정된 그리드 셀에 대해, 질의에 포함된 도로 구간에서의 주행 시간을 병렬적으로 측정한다. 아울러 리듀스 함수에서는 출발 시간 및 구간별 주행 시간을 바탕으로 맵 함수의 결과를 병합함으로써, 최종 결과를 생성한다. 이를 통해 공간 빅데이터 분석을 통한 주행 시간 예측 기법의 처리 시간 및 결과 정확도를 향상시킨다.

• Journal of Advanced Navigation Technology
• /
• v.28 no.1
• /
• pp.1-14
• /
• 2024

Global navigation satellite system (GNSS) providing position, navigation and timing (PNT) services consist of satellite, ground, and user systems. Monitoring stations, a key element of the ground segment, play a crucial role in continuously collecting satellite navigation signals for service provision and fault detection. These stations detect anomalies such as threats to the signal-in-space (SIS) of satellites, receiver issues, and local threats. They deliver received data and detection results to the master station. This paper introduces the main monitoring algorithms and measurement pre-processing processes for quality assessment and fault detection of received satellite signals in current satellite navigation system monitoring stations. Furthermore, it proposes a strategy for the development of components, architecture, and algorithms for the new regional navigation satellite system (RNSS) monitoring stations.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.6
• /
• pp.3478-3489
• /
• 2014

Because the increased number of Internet users and the common use of IT technology via the expansion of domestic IT infrastructure have increased the web site use of companies, Internet users have begun to experience a range of online websites. In a digital environment, entrepreneurial companies who have limited resources will require effective management by analyzing the critical factors of the website quality assessment and focusing their resources to seize the market because the website quality built in the company directly affects the satisfaction and purchase activity of the customers. In this study, a total of 523 surveys from the customers visiting online websites of the entrepreneurial companies were collected to analyze the factors between the influencing factors and satisfaction and purchase intention using the ServQual method in the AMOS 18.0 program. This analysis showed that the customers visiting the website are satisfied with the factors of tangibility, reliability and responsiveness of visited websites, and the factor of community, which indicates that the level of customer activity in the web sites is related significantly to the customers' purchase intentions.

• Journal of KIISE:Software and Applications
• /
• v.31 no.8
• /
• pp.980-990
• /
• 2004

The component-based development methodology aims at the high state of abstraction and the reusability with components larger than classes. It is indispensible to measure the component so as to improve the quality of the component-based system and the individual component. And, the quality of the component should be improved through putting the results into the process of the development. So, it is necessary to study the component metric which can be applied in the stage of the component analysis and design. Hence, in this paper, we propose component cohesion, coupling, independence metrics reflecting the information extracted in the step of component analysis and design. The proposed component metric bases on the similarity information about behavior patterns of operations to offer the component's service. Also, we propose the redesigning process for the improvement of component design. That process uses the techniques of clustering and is for the thing that makes the component as the independent functional unit having the low complexity and easy maintenance. And, we examine that the component design model can be improved by the component metrics and the component redesigning process.

• Journal of Internet Computing and Services
• /
• v.14 no.4
• /
• pp.13-24
• /
• 2013

IEEE 802.15.4 network and WiFi network are installed to overlap each other and configured to use adjacent frequency bands in which case the communication service required by applications can not be guaranteed because of randomly increased frame transmission delay and frequent frame transmission failures at nodes in IEEE 802.15.4 network. In this paper, transmission delay model at IEEE 802.15.4 nodes and an experimental system to evaluate the interference from WiFi traffic are described, then elements for the evaluation of interference are measured with the analysis of their characteristics. A sequential method of using medium access layer and physical layer elements of IEEE 802.15.4 protocols is proposed to decide interference from WiFi network. With the proposed method, if an evaluation function having frame transmission failures and transmission delay as variables returns a value greater than a threshold, intensive measurements of wireless channel power are carried out subsequently and the final decision of interference is made by the calculated average channel power. Experimental results of the method show that the decision time is reduced with increased frequency of decision in comparison to an other similar method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.10a
• /
• pp.527-530
• /
• 2014

DASH is a well-known streaming technology, which was proposed in 2010 by MPEG and standardized in 2011. Major multimedia contents service providers, including Apple, Microsoft, and Adobe are all using this technology to support their media streaming services. Whenever a new service is requested to the server, the DASH technology helps servicing the multimedia streaming to client by recognizing the capacity of network and by adapting the quality of the multimedia contents. In DASH, the quality of multimedia contents will be automatically lowered to meet the fluctuating network status, when undesirable breaks interrupt the network. In this paper, we classified and analysed the advantages and disadvantages of DASH researches in three aspects: bit-rate measurement method, bandwidth aggregation method; rate adaptation metrics, algorithms and logics; user's experiences and QoE.

• Journal of the Institute of Convergence Signal Processing
• /
• v.24 no.2
• /
• pp.112-118
• /
• 2023

Internet of Things(IoT) technology is developing to a stage where the Internet and objects are connected and objects themselves analyze and judge data to interconnect the real world and the virtual world in real time. This technology consists of sensors, actuators, devices, and networks, and it is being applied in various fields. As the number of IoT devices and applications increases, data traffic also increases. In this paper, a messaging system is designed and implemented in order to analyze the performance between an IoT device and MQTT broker. The experimental was performed to measure MQTT-based round-trip time and message transmission time between the IoT device and the broker. The result shows that there is no packet loss, and propagation delay affects round-trip time.

• The Journal of the Korea Contents Association
• /
• v.20 no.9
• /
• pp.308-317
• /
• 2020

The purpose of this study is to investigate the effect of differences between job expectations and satisfaction on overall employee satisfaction. A survey was conducted on administrative staff at S University in Seoul for 8 days from December 17, 2018 to December 24, 2018. First, the difference between job expectation and job satisfaction, a significant negative difference occurred for all 15 measurement variables. Second, the factors of work cost and personnel system were found to have a significant negative effect on employee satisfaction. If the expected discrepancy between work cost and personnel system increases by 1, employee satisfaction decreases by 0.35 and 0.24, respectively. Third, among the sub-categories of work cost and personnel system, department allocation and division of duties, proper compensation payment, rationality of compensation decision process, and good welfare system were found to have a significant correlation. By analyzing the significant correlation between expected discrepancies and employee satisfaction, focusing on items that can increase employee satisfaction while lowering the financial burden, narrowing the expected discrepancy of staff increases employee satisfaction and improves the quality of education services.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.3B
• /
• pp.380-389
• /
• 2010

Since the internet is intend to be the best effort service, the system that stream a large amount of high quality medias need a techniques to overcome the network status for implementation. In this paper, we design and implement a method that estimate quickly whether network permits the needed bandwidth of media and a method that control QoS through that. Presented system uses Relative One-Way Delay(ROWD) trend in the case of the former, and leverages temporal encoding among Scalable Video Coding(SVC) that is apt to apply real time comparatively in the case of the latter. The streaming server classifies the medias by real time to several rates and begins transmission from top-level and is reported ROWD trend periodically from the client. In case of the server reported only 'Increase Trend', the sever decides that the current media exceeds the available bandwidth and downgrades the next media level. The system uses probe packet of difference quantity of the target level and the present level for upgrading the media level. In case of the server reported only 'No Increase Trend' by the ROWD trend response of the probe packet from client, the media level is upgraded. The experiment result in a fiber to the home(FTTH) environment shows progress that proposed system adapts faster in change of available bandwidth and shows that quality of service also improves.

• Journal of Digital Convergence
• /
• v.15 no.12
• /
• pp.137-145
• /
• 2017

The purpose of this study is to suggest the measures to measure the shopping satisfaction and to increase the shopping satisfaction. We conducted surveys and conducted empirical analysis on Chinese tourists visiting duty free shops in Busan using direct survey method. The results of this study are as follows. First, factor analysis for subdividing the duty - free choice attribute was analyzed as store attribute, product attribute, and service attribute. Second, based on this analysis, the effect of each attribute on shopping satisfaction showed statistically significant positive results. Third, the analysis of the relative size of the effects of analytic attributes on satisfaction showed that store attributes were the highest. That is, the quality of duty-free shops, services, and products increases overall shopping satisfaction. Therefore, it can be said that the strategy implementation that improves the quality of the attributes affecting the satisfaction is expected to contribute to the improvement of the management performance, and suggests the management implications for the activation of the operation of the duty - free shop. Future studies will be more meaningful if more variety of shopping places are studied.