• Speech Sciences
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• v.6
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• pp.163-179
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• 1999

For the set up, management and repair of a mobile communication system, continuous estimation of speech quality is required. Speech quality measurement can be conducted by listener's judgement in a subjective test such as MOS (Mean Opinion Score) test. However, this method is laborious, expensive and time-consuming, it is advisable to predict subjective speech quality via objective measures. This paper presents a robust objective speech quality measure, PLP-CMS (Perceptual Linear Predictive-Cepstral Mean Subtraction), which can predict subjective speech quality in mobile communication systems. PLP-CMS has a high correlation with subjective quality owing to PLP (Perceptual Linear Predictive) analysis and shows a robust performance not being influenced by PSTN (Public Switched Telephone Network) channel effects due to CMS (Cepstral Mean Subtraction). To prove the performance of our proposed algorithm, we carried out subjective and objective quality estimation on speech samples which are variously distorted in a real mobile communication system. As a result, we demonstrated that PLP-CMS has a higher correlation with subjective quality than PSQM (Perceptual Speech Quality Measure) and PLP-CD (Perceptual Linear Predictive-Cepstral Distance).

• Journal of the Korean Professional Engineers Association
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• v.27 no.2
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• pp.42-54
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• 1994

Nowadays communication network is steadily changing from a main body of telephone to a network which is creating new services such as multimedia etc. Jhis article introduces a bud of new service and new network which are able to sustain the above service. Including Korea, world advanced countries have been digitatizing their network with N-ISDN (narrowband ISDN) by e.g. 64K b/s and 1.5M b/s. New service by N-ISDN are extraordinary, though it can not solve all kinds of services. To solve these problems, a solving platform should be constituted. B-ISDN(broadband ISDN), as a platform has to be built to deal with almost all uinds of services, whatever the communication speed, communication mode or communication quality may be. Korea Telecommunication Authority(KTA) opened the narrowband ISDN(N-ISDN) at the end of 1993. This was one step previous opening of the broadband ISDN(B-ISDN) service scheduled to be rendered in 2001. B-ISDN, receiving and transmitting by far more information with high speed than the N-NSDN does, is one of G-7 Progects which the Korean government is driving foreward to raise the national scientific power to seven advan ced countries. This is also linked with an extremely high speed information network scheduled to be built by the Ministry of Communications in 2015.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.3
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• pp.652-663
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• 1996

In this paper, we analyze the blocking probability of a call in a PC communication network. In a PC communication network, a call generated from the PSTN (public switched telephone network) requests the connection to the ICPS(information communication processing system) which interconnects the the PSTN and the PSDN(packet switched data network). Then, as a second step, a packet call is requested to the specific service database attached in the PSDN. The call blocking probabilies are analyzed for these two interface points, the PSTN interface ports of the ICPS and the PSDN interface link of the database. We also present some numerical results to show the effects of the system parameters on the performance of the network. The results show the effects of the capacity of each interface point on the performance point.

• Journal of IKEEE
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• v.24 no.2
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• pp.453-460
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• 2020

This paper, UHF band integrated communication antenna for ship communication is designed as a flat type that can be mounted on the integrated mast among integrated communication antennas such as integrated communication, ship communication, broadcasting, and telephone of the ship. The unified mast mounted antenna is an integrated communication antenna applied to the Navy's KDDX, which is an optimized type of integrated communication antenna including a 'composite slope' structure including operational capability, survivability, and improved operability and maintainability. The existing rotary radar and a plurality of monopole-type communication antennas were changed from an irregularly attached shape to the mast exterior to an integrated mast shape including a flat-type integrated communication antenna. the radar reflection area index (RCS) is significantly lowered and compared to overseas products. The goal is to develop a gain broadband antenna.

• The Journal of Korean Society for School & Community Health Education
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• v.6
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• pp.75-87
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• 2005

The purpose of this study was to describe elementary school students' health communication needs based on school-based health fairs by students' demographic characteristics and school health education experiences. A self-administered survey was conducted to a total of 851 fifth-grade students in 8 elementary schools in Seoul. For survey participant sampling, Seoul area was divided into four districts: north, south, east, and west, and two elementary schools were selected from each district by the stratified convenient sampling process. Three class 5th-grade students in each selected school finished the survey. Questionnaires and survey instruction letters were delivered to vice-principals in the designated schools and the vice-principals managed the survey process. The survey Questionnaire included demographic characteristics (sex, parent's marital status, parents' educational status, famil financial status, the person whom was with after school, and daily computer hour), health education experiences (health education at school, and school health education satisfaction), and health communication types. The health communication types were reorganized into eight types based on comprehensive literature review on health fairs (or child and adolescence. The health communication types were 'health exam and advice fair,''health promotion advertising and campaign,' 'health-related exhibition and experience fair,' 'profession visit-in-school education,' 'health-related VCR or movie festival,' 'health-related institute visits,' 'internet health counseling,' and 'telephone health counseling.' Regarding demographic characteristics, sex, family financial status, and academic performance were significant factors related to health communication need scores (p <.05). Girl, high level of family financial status, and excellent academic performance score were related to high score of health communication need. In terms of school health education experience, taking regular class for health education and satisfaction with school health education were linked to higher health communication need scores. This result discusses that experience and satisfaction with school health education largely contribute to building participants' health communication concepts and needs.

• Journal of Digital Convergence
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• v.17 no.2
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• pp.91-100
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• 2019

The purpose of this study was to provide basic data for the selection of educational contents when developing a course for cultivating global business communication competence. Reviewing previous studies on sub-elements of global competence, the researcher selected the sub-elements of global business communication competence. A survey was conducted on 148 employees of 20 companies regarding the importance of the sub-elements of global business communication competence. As a result, it was concluded that the sub-elements of relatively high importance-English email writing, reading and understanding of English materials and documents, telephone English, business English conversation, understanding of other cultures, communication skills, business knowledge-should be included in the educational contents of a course for cultivating global business communication competence.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.1-8
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• 2010

Wireless multimedia service through the access to mobile telephone network or data network is a vital part of contemporary life, and the demand for frequency spectrum for new services is expected to explode as the ubiquitous computing proliferate. Cognitive radio is a technology, which automatically recognizes and searches for temporally and spatially unused frequency spectrum, then actively determines the communication method, bandwidth, etc. according to the environment, thus utilizing the limited spectrum resources efficiently. In this paper, we investigate the effects of imperfect sensing, misdetection and false alarm, on the primary and secondary users' spectrum usage through the analysis of continuous time Markov Chain. We analyzed the effects of the parameters such as sensing error, offered load on the system performance.

• Asia pacific journal of information systems
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• v.20 no.2
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• pp.103-124
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• 2010

Social communications using information and communication technologies (ICT) for social interactions have been making a significant impact on task performance in organizations. However, most of the existing studies on ICT (e.g., telephone and email) have only focused on technical improvement of communication efficiencies (e.g., information exchange and storage). In this paper, we claim that ICT may be another alternative source of knowledge creation that enables employees to work, find solutions, and achieve their goals faster and better. We investigate the impact of ICT in terms of both tasks and social aspects with knowledge creation as task performance. Also, we investigate the moderating effect of media synchronicity on these relationships. This study contributes to the understanding of contemporary communications media usage and its performance in organizations. We collected and analyzed survey data of 248 company employees, using PLS. The results indicate that task urgency and social influence directly affect ICT usage, and even knowledge creation. Also the media synchronicity moderates the relationship between the characteristics of a given task and ICT usage and the relationship between ICT usage and knowledge creation. Theoretical and practical implications of these findings are also discussed in the paper.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.209-214
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• 2002

We developed a small, remote controlled observation ship that can reduce the cost of gathering data for marine and coastal environments. The control system is composed of three microprocessors, one is for overall mission control, another for control of propulsion motors, and the other for sensor operation. For communication system, we adopt direct and indirect methods based on the wireless modem of commercial cellular telephone. The former is a direct communication between the modems of the ship and the server, and the latter is an indirect communication via internet between the ship and the server. The performance of the ship is demonstrated with the results produced by sets of experiments.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.4
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• pp.469-474
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• 2014

Installed on telephone poles laid scrambling to monitor the status of the communication lines, and cost information can provid eadditional information tools to develop systems to support on-site monitoring. Aerial support for a maintenance monitoring module to apply an embedded system, and information processing applications manufactured. In this study, a comprehensive plan in accordance with the government's aerial maintenance work to prevent accidents spread support for the device to immediately take advantage of big cities and aerial maintenance business, Construction worker accused of bias and aims to improve efficiency of maintenance puts.