• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1461-1472
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• 2000

Recently, the mobile users seem to be rapidly increasing and then the capacity limit will be reached at close hand. In these situations, to provide them with good quality of service in the coming future, newly planned cell design is needed. In the next generation mobile communication systems, namely IMT-2000, good quality services will be possible only by designing the cell structure hierarchically with the help of appropriate cell planning. In the research process, the standardization reports on the future mobile cellular IMT-2000 system (3GPP) are investigated and the parameters, that are essential to cell planning, are also researched. Modeling of IMT-2000 radio link and the numerical analysis on that make it possible to calculate the forward/reverse link budget, system capacity call blocking probability Erlang capacity and cell coverage. In planning the cell of IMT-2000 system, various parameters are considered, such as hierarchical cell structure, number of users, data service forms and propagation area environments. From the results, efficient cell planning methods are proposed. Through this thesis efficient cell planning and maximum capacity will be achieved in the beginning of commercial IMT-2000 service.

• The Korean Journal of Air & Space Law and Policy
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• v.8
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• pp.297-332
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• 1996

It is well observed in the satellite telecommunication policy of several States that legal constraints imposed upon the service coverage of satellite telecommunication as well as broadcasting are to be relaxed in a progressive way. Major aspects of such policy change lie in the adoption of policy refusing traditional concept of national frontier. In the case of direct broadcasting satellite service, while a debate upon the legal issues regarding the spill-over effect of that service is no more major concern of the States, many multinational enterprises are looking for strategic alliance for regional or global DBS project. On the other hand, an implementation plan for connecting the world through global mobile personal communication satellite system is being pursued by several joint effort of multinational firms. Legal issues arise regarding the regulatory competence of each State, Especially, a controversial issue is concerning the sovereign right well recognized upon the regulation of telecommunication. This study is focusing upon the evolution of such policy change for the purpose of allowing us to expect future develpment of worldwide satellite telecommunication policy environment.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.496-498
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• 2005

We reported that high dielectric hafnium oxide nano-film deposited by thermal atomic layer deposition on the poly-silicon film (poly-Si). The poly -Si film was produced by plasma enhanced chemical vapor deposition and excimer laser annealing. We used the hafniu m chloride ($HfCl_4$) and water as the precursors and analyzed the hafnium oxide film by transmission electron microscope and secondary ion mass spectrometer. Hafnium oxide produced by the ALD method showed very good coverage on the rough surface of poly-Si film. While deposited with 200 cycles, these hafnium oxide films revealed a relatively smooth surface and good uniformity, but the cumulative roughness produced by the incomplete reaction was apparent when the amount of deposition cycle increased to 600 cycles.

• The KIPS Transactions:PartD
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• v.12D no.6 s.102
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• pp.869-874
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• 2005

In the recent years there has been an increase of service competition in the activity of product selling, especially in the extension of warranty coverage and qualify. The variables in connection with the service competition are not crisp, and required the expertise of the production line. It thus becomes all the more necessary to use subtler tools as decision supports. These problems are typical not only of product companies but also of financial organizations, credit institutions, insurance, which need predictions of credibility for firms or persons in which they have any kind of interest. A suitable approach for minimizing the risk is to use a knowledge-based system. Most often expert systems are not standalone programs, but are embedded into a larger application. The aim of this paper is to discuss an approach for developing an embedded fuzzy expert system with respect to the product selling policy, especially to present the decision system of automobile selling activity around the extension of warranty coverage and quality. We use the MATLAB tools which integrates computation, visualization, and programming in an easy-to-use environment where problems and solutions are expressed in familiar mathematical notation. Also, we present the API functions embedding into the existing application.

• Informatization Policy
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• v.18 no.2
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• pp.85-98
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• 2011

This paper attempts to develop an index of mobile telecommunications service quality through econometric analysis using data of the leading telco in each OECD country. CapEx of the operator was selected as a proxy variable to represent the quality of the service. To eliminate the part which is dependent on the population and size from CapEx, however, CapEx was regressed on population, area, 3G coverage, Herfindahl-Hirschman Index (HHI) of mobile market, EBITDA margin, and market share of the leading operator. Then, the part of CapEx, which was explained by size and population, was subtracted from CapEx, and the remaining part was regarded as the quality index of mobile telecommunications service. Comparisons among quality indexes of each country revealed that the service quality in Korea and Japan is better than that of France, UK and Germany.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.7
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• pp.2895-2898
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• 2015

Background: In the years 2014, coverage rates of cervical cancer screening in Nakornnayok province accounted to 76.5%. This was lower than the government's specified goal of 80%. Community health volunteers are members of a Thai healthcare alliance established to help promoting healthcare service communication and collaboration at the primary level. Such village health volunteers (VHVs) are established in most villages. Objective: To assess the knowledge and attitudes of cervical cancer screening among VHVs. Materials and Methods: The subjects were 128 VHVs from four Nakornnayok sub-districts; namely KlongYai, Chomphol, Buangsan and Suksara, Thailand. The study was conducted from December 2014 to January 2015. The questionnaire was designed to assess the knowledge and attitude of cervical cancer screening provided by the VHVs. In addition, cervical cancer screening coverage rates of each area were collected. The demographic data, scores of knowledge, attitudes, practices and the cervical cancer screening coverage rates were analyzed by one-way ANOVA. Results: The questionnaire reliability was assessed as 0.81. The total knowledge and attitude scores were 10 and 15 points. The mean knowledge scores of KlongYai, Chomphol, Buangsan and Suksara were 6.8, 7.0, 6.5 and 9.0 points, respectively. The VHVs had a high level of overall knowledge about cervical cancer screening. The mean attitude scores were 12.4, 13.2, 13.4 and 13.1 points. VHVs had a positive attitude to the promotion of cervical cancer screening at the overall level. The percentages of VHVs promoting cervical cancer information in respective districts were 72.2, 94.3, 94.9 and 50.0. However, the cervical cancer screening coverage rates were 62.4%, 34.7%, 80.3% and 47.3% respectively. Conclusions: The knowledge, attitudes and percentages of promoting information of cervical cancer screening among VHVs in the four sub-districts were high but did not correlate with the cervical screening coverage rates for each area. VHVs needed to understand socio-cultural beliefs of the women in the target population and design suitable strategies to encourage higher cervical screening coverage.

• Journal of KIISE:Information Networking
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• v.36 no.4
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• pp.339-350
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• 2009

In wireless sensor networks, the limited battery resources of sensor nodes have a direct impact on network lifetime. To reduce unnecessary power consumption, it is often the case that only a minimum number of sensor nodes operate in active mode while the others are kept in sleep mode. In such a case, however, the network service can be easily unreliable if any active node is unable to perform its sensing or communication function because of an unexpected failure. Thus, for achieving reliable sensing, it is important to maintain the sensing level even when some sensor nodes fail. In this paper, we propose a new fault-tolerance scheme, called FCP(Fault-tolerant Coverage Preserving), that gives an efficient way to handle the degradation of the sensing level caused by sensor node failures. In the proposed FCP scheme, a set of backup nodes are pre-designated for each active node to be used to replace the active node in case of its failure. Experimental results show that the FCP scheme provides enhanced performance with reduced overhead in terms of sensing coverage preserving, the number of backup nodes and the amount of control messages. On the average, the percentage of coverage preserving is improved by 87.2% while the additional number of backup nodes and the additional amount of control messages are reduced by 57.6% and 99.5%, respectively, compared with previous fault-tolerance schemes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4D
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• pp.451-457
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• 2008

Establishing realistic bus service coverage is needed to build optimum city bus line networks and reasonable bus service coverage areas. The purposes of this study are understanding the characteristics of the present walking time and marginal walking time of small-medium cities and constructing an ANFIS (Adaptive Neuro-Fuzzy Inference System) model to estimate the marginal walking time for certain age and income. The cities of Masan, Chongwon and Jinju are selected for study cities. The 80 percentile of present walking time of bus users of these cities are 10.2-11.1 minutes, thus the values are greater than the 5 minutes of the maximum walking time in USA and the marginal walking times of 21.1-21.8 minutes are much greater. An ANFIS model based on pulled data of the cities are constructed to estimate the marginal walking time of small-medium cities. Analyzing the relationship between marginal walking time and age/income by using the model, the marginal walking time decreases as the age increases, but is near constant from the age of 25 to 35. And the marginal walking time is inversely proportional to the income. In comparing the surveyed and the estimated values, as the statistics of coefficient of determination, MSE and MAE are 0.996, 0.163, 0.333 respectively, it may be judged that the explainability of the model is very high. The technique developed in this study can be applied to other cities.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.3
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• pp.109-115
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• 2019

Most demand forecasting studies for telecommunication services have focused on estimating market size at the introductory stage of new products or services, or on suggesting improvement methods of forecasting models. Although such studies forecast business growth and market sizes through demand forecasting for new technologies and overall demands in markets, they have not suggested more specific information like relative market share, customers' preferences on technologies or service, and potential sales power. This study focuses on the telecommunication service industry and explores ways to calculate the relative market shares between competitors, considering competitive situations at the introductory stage of a new mobile telecommunication service provider. To reflect the competitive characteristics of the telecommunication markets, suggested is an extended conjoint analysis using service coverage and service switching rates as modification variables. This study is considered to be able to provide strategic implications to businesses offering existing service and ones planning to launch new services. The result of analysis shows that the new service provider has the greatest market share at the competitive situation where the new service covers the whole country, offers about 50% of existing service price, and allows all cellphones except a few while the existing service carrier maintains its price and service and has no response to the new service introduction. This means that the market share of the new service provider soars when it is highly competitive with fast network speed and low price.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.4
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• pp.269-277
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• 2022

In this paper, we overview the system development status of the national maritime precise point positioning-real-time kinematic (PPP-RTK) service in Korea, also known as the Precise POsitioning and INTegrity monitoring (POINT) system. The development of the POINT service began in 2020, and the open service is scheduled to start in 2025. The architecture of the POINT system is composed of three provider-side facilities-a reference station, monitoring station, and central control station-and one user-side receiver platform. Here, we propose the detailed functionality of each component considering unidirectional broadcasting of augmentation data. To meet the centimeter-level user positioning accuracy in maritime coverage, new reference stations were installed. Each reference station operates with a dual receiver and dual antenna to reduce the risk of malfunctioning, which can deteriorate the availability of the POINT service. The initial experimental results of a testbed from corrections generated from the testbed network, including newly installed reference stations, are presented. The results show that the horizontal and vertical accuracies satisfy 2.63 cm and 5.77 cm, respectively. For the purpose of (near) real-time broadcasting of POINT correction data, we designed a correction message format including satellite orbit, satellite clock, satellite signal bias, ionospheric delay, tropospheric delay, and coordinate transformation parameters. The (near) real-time experimental setup utilizing (near) real-time processing of testbed network data and the designed message format are proposed for future testing and verification of the system.