• 경영과학
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• 제22권2호
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• pp.35-49
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• 2005

When new services are introduced, interaction among existing and new services has to be considered. The interaction can be characterized by the substitution or complementary effect among services. This paper analyzes how the interaction among services affects the customers' subscription decision in telecommunication services industry. Based on a face-to-face in-depth survey from a sample of 1,200 respondents, a new wireless internet access service or WiBro is analyzed to identify the substitution/complementary effect in relation to the existing other telecommunication services. Additionally, the important factors explaining both customers' subscription and substitution decisions are identified. The analysis results indicate that males and students are more likely to subscribe WIBro service. Interestingly, family size positively affects the subscription decision. However, heavy users of on-line game are reluctant to subscribe WiBro service. Among the potential WiBro subscribers, the customers who are less satisfied with the existing fixed line broadband internet access service are more likely to stop subscribing the fixed line service, which implies substitution by a new service. We believe that the consideration of the interactions among services is essential to devise a winning strategy for the new services in the highly uncertain telecommunications business environment.

• 한국항행학회논문지
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• 제23권6호
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• pp.507-514
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• 2019

FCC (Federal Communications Commission)는 해군 레이더 및 고정지구국 제1 업무로 사용하고 있는 3.5 GHz (3,550 - 3,700 MHz) 대역을 공동사용으로 CBRS (citizen broadband radio service) 시스템이라는 스몰셀의 저전력망 구축이 가능하도록 규정을 제정하였다. CBRS를 위한 공동사용 기술은 3-tiered SAS (spectrum access system)에 기반하여 하위계층 유저로부터 상위계층 유저를 보호하고 가용 스펙트럼을 최적으로 이용할 수 있어 국내에서도 적극적으로 CBRS 도입을 검토하기 시작하였다. 그러나 3.5 GHz 대역은 국내에서 이미 5G용으로 할당되어 있어, 본 논문에서는 3,700 - 5,000 MHz 대역에서 주파수 공동사용 연구를 수행하였다. 그 결과 3.8 GHz 대역(3,800 - 3,900 MHz)이 FSS(fixed satellite service)용으로 한정되어 있어, 주파수 공동사용이 가능한 대역으로 검토되었으며 FSS 지구국에 미치는 간섭분석을 수행하여 국내의 CBRS 도입을 모색하고자 한다.

• East Asian Economic Review
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• 제28권2호
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• pp.143-174
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• 2024

This paper empirically examines the relationship between outward foreign direct investment (OFDI) of Korean manufacturing firms and the servicification of domestic employment using a firm-level panel data. In this study, considering the issue of low productivity in the Korean service sector, we categorize service employment into core and non-core services and investigate their relationship with OFDI using the firm-fixed effects model. The empirical results show that the share of core service employment exhibits a positive correlation with the extensive OFDI. On the other hand, the share of non-core service employment, which is expected to generate relatively low value-added, does not show a significant relationship with the extensive OFDI. When we divide the samples based on host countries and the type of subsidiaries, the impact on servicification varies depending on the technological capabilities of host countries and their participation in global value chains. Our study suggests that Korean manufacturing firm's internationalization strategies may facilitate a transition from labor-intensive employment, like the cases in advanced countries, to technology-intensive employment through OFDI and other means.

• 약학회지
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• 제57권3호
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• pp.213-218
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• 2013

This study examines factors associated with fixed budgets for pharmaceuticals and clawback system for pharmaceutical industry in European countries. We used information from a survey held in 2005~2006 by Austrian Health Institute. Several information including pharmaceutical pricing policies, marketing conditions for pharmaceutical industry and patient' choice of drugs was collected. Five out of twenty five countries in EU were considered as countries with fixed budgets for pharmaceuticals and remaining 20 countries were considered as countries without fixed budget system. Comparisons were made for each information. Countries with fixed budgets for pharmaceuticals were more likely to have internal (or external) reference pricing system and other pricing mechanisms. In addition, they were more likely to permit pharmaceutical industry to be engaged in public advertising and information provision towards patients. They guaranteed patient participation in drug choice decisions. The countries with fixed budgets for pharmaceuticals were more likely to have conditions that enable the fixed budget system to work better compared to those without fixed budget system. Therefore, the study results imply that we need to check whether we have similar conditions to the countries that already have fixed budgets for pharmaceuticals when we want to introduce fixed budget mechanism for pharmaceuticals in Korea in the future.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.1033-1036
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• 1999

In storage technology it is desirable to have greater storage capacity at lower costs. Data compression addresses these demands by reducing the amount of data that must be stored to a given size of media, thus lowering the cost of that storage device. In data compressions it is desirable to have faster transfer rates at lower costs. Data compression addresses these demands by reducing the amounts of data that must be transferred over a media with a fixed bandwidth, thus reducing the connection the. Data compression also reduces the media bandwidth required to transfer a fixed amount of data with a fixed quality of service, thus reducing the costs on this service.

• 한국인터넷방송통신학회논문지
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• 제15권5호
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• pp.85-90
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• 2015

스마트폰을 활용한 기업 내 업무 환경은 이동 오피스라는 개념으로 기존 유선전화 중심의 서비스에서 스마트폰을 이용한 전화서비스로 구현한 WiFi FMC(Fixed Mobile Convergence)분야와, PC중심의 정보시스템 단말 기능 대신 스마트폰을 활용하여 기업내/외부에서 시스템에 접속하여 업무를 처리할 수 있게 하는 EMS(Enterprise Mobility Service) 분야로 나뉘어 발전하고 있다. 본 논문에서는 텔레포니 서비스의 기업형 FMC의 문제점을 보완하여 IP-PBX와 연동하며 IMS(IP Multi-Media Subsystem) 서비스를 수행 할 수 있는 FMC 컨트롤러를 개발 했다. 본 컨트롤러는 FMC 서비스 자동등록, 모바일 소프트폰의 음성품질 향상, 휴대폰으로 기업 내 어느 곳에서도 통화를 할 수 있다 는 이동성을 제공하고, IP-PBX 내에서 모바일 소프트폰 상태정보를 활용한 FMC LCR(Least Cost Routing)기능도 구현 했다.

• Journal of Communications and Networks
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• 제16권2호
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• pp.130-139
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• 2014

Due to the unpredictable nature of channel availability, carrying delay-sensitive traffic in cognitive radio networks (CRNs) is very challenging. Spectrum leasing of radio resources has been proposed in the so called coordinated CRNs to improve the quality of service (QoS) experienced by secondary users (SUs). In this paper, the performance of coordinated CRNs under fixed-rate with hard-delay-constraints traffic is analyzed. For the adequate and fair performance comparison, call admission control strategies with fractional channel reservation to prioritize ongoing secondary calls over new ones are considered. Maximum Erlang capacity is obtained by optimizing the number of reserved channels. Numerical results reveal that system performance strongly depends on the value of the mean secondary service time relative to the mean primary service time. Additionally, numerical results show that, in CRNs without spectrum leasing, there exists a critical utilization factor of the primary resources from which it is not longer possible to guarantee the required QoS of SUs and, therefore, services with hard delay constraints cannot be even supported in CRNs. Thus, spectrum leasing can be essential for CRN operators to provide the QoS demanded by fixed-rate applications with hard delay constraints. Finally, the cost per capacity Erlang as function of both the utilization factor of the primary resources and the maximum allowed number of simultaneously rented channels is evaluated.

• Journal of Communications and Networks
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• 제9권2호
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• pp.159-166
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• 2007

In this paper, we propose an efficient and robust interference mitigation technique based on a nullsteering multi-user multiple-input multiple-output (MU-MIMO) spatial division multiple access (SDMA) scheme for frequency sharing between IMT-advanced and fixed satellite service (FSS) in the 3400-4200 and 4500-4800 MHz bands. In the proposed scheme, the pre-existing precoding matrix for SDMA unitary precoded (UPC) MIMO proposed by the authors is modified to construct nulls in the spatial spectrum corresponding to the direction angles of the victim FSS earth station (ES). Furthermore, a numerical formula to calculate the power of the interference signal received at the FSS ES when IMT-Advanced base stations (BS) are operated with the interference mitigation technique is presented. This formula can be derived in closed form and is simply implemented with the help of simulation, resulting in significantly reduced time to obtain the solution. Finally, the frequency sharing results are analyzed in the co-channel and adjacent channel with respect to minimum separation distance and direction of FSS earth station (DOE). Simulation results indicate that the proposed mitigation scheme is highly efficient in terms of reducing the separation distance as well as robust against DOE estimation errors.

• 한국통신학회논문지
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• 제10권6호
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• pp.273-286
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• 1985

오늘날 衛星通信方式은 INTELSAT와 INMARSAT와 같은 國際組織을 통하여 全世界的인 國際業務를 제공하고 있으며 衛星通信技術은 陸上에서의 固定業務뿐만 아니라 海上移動業務에도 큰 變革을 가져왔다. 우리나라에서는 INTELSAT를 통한 國際固定衛星業務는 先進國에 비하여 손색이 없으나 INMARSAT시스템에 의한 海上移動衛星業務面의 施設과 技術은 世界水準에서 落後되어 있다. 本 論文에서는 먼저 위성통신방식의 발전과정을 論하고 그 시스템의 早速한 國內導入上 問題點을 分析하고 끝으로 INMARSAT 시스템의 導入促進方向을 다음과 같은 面에서 提案하고자 한다. 1. 海上·陸上地球局의 設置 2. 새로운 通信長資格基準의 設定 3. 海上移動衛星業務를 위한 國際協力의 增進 4. INMARSAT 시스템의 硏究機閱의 設置

• 보건의료산업학회지
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• 제11권3호
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• pp.1-11
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• 2017

Objectives : The purpose of this study was to analyze factors affecting the performance of public hospitals in South Korea. Methods : We collected management performance data from 2013 to 2015 from income statements, balance sheets, and annual reports from 32 local public hospitals. The dependent variable used was profitability, which included operating margin, return on assets and net profit to gross revenues. The independent variables were general characteristics, liquidity, stability, and activity. Results : Patient revenues, total assets, and total capital had increased steadily but patient expenses had increased to a greater extent. Operating profit, and net profit were consistently in deficits and the management status of local public hospitals had recently been in difficulty. The debt ratio, quick ratio, ratio of fixed liability and fixed assets turnover rate have a significant positive(+) effect on performance in the years 2013-2015. Conclusions : We suggest management strategies for these hospitals based on the results analyzed.