• Journal of Positioning, Navigation, and Timing
• /
• 제12권3호
• /
• pp.307-314
• /
• 2023

Wide-Area Differential Global Positioning System (WADGPS) is a system that operates a number of reference stations to provide correction information to improve the accuracy of GPS users, and it is available to service users within the area where the wide-area reference stations are installed. Recently, as positioning information has been used in various applications, the need for WADGPS for precise navigation in long-distance spaced areas where the wide-area reference stations cannot be installed has been raised. This paper tested the user navigation performance outside the wide-area reference stations of the WADGPS system, which serves both GPS Precise Positioning Service (PPS) and Standard Positioning Service (SPS) users. Static and dynamic tests were conducted using vehicles, and as a result, position accuracy improvement through WADGPS was confirmed even at points hundreds of kilometers outside the network area of the wide-area reference stations. Through this, the performance of the PPS/SPS correction system and the possibility of expanding the service area were confirmed.

• 대한지역사회영양학회지
• /
• 제7권6호
• /
• pp.852-862
• /
• 2002

The purposes of this study were 1) to review the Medical Nutrition Therapy (MNT) Act of the United States, 2) to introduce the efforts of the American Dietetic Association (ADA) to expand the Medicare coverage for MNT and 3) to provide information about the reimbursement under Medicare Part B for the cost of MNT. The MNT Act defined MNT services as “the nutritional diagnostic, therapeutic, and counseling services provided by a Registered Dietitian or nutritional professional for the purpose of managing diabetes or renal diseases”. Also, the MNT Act defined “conditions for coverage of MNT”, “limitations on coverage of MNT”, and “qualifications of MNT service provider”. To expand the coverage of Medicare to include MNT, the ADA realized the need for development of a protocol for MNT, as well as studies to evaluate the effectiveness and cost-effectiveness of the MNT protocol developed. Therefore, the ADA supported the studies to develop a strong database of scientific investigations of nutritional services. Furthermore, the ADA needed credible data that could be used by Policy makers, so the ADA contracted with the Lewin Group to if out the study to gather the additional data needed to strengthen the ADA's position. In the report of the Lewin Group, which was entitled, “The Cost of Covering Medical Nutrition Therapy under Medicare : 1998 through 2004”, it was concluded, that if coverage for MNT in the Part B portion of Medicare had begun in 1998, by 2004, approximately $ 2.3 billion would have been saved through reduced hospital spending under Part A of Medicare ($ 1.2 billion) and reduced physician visits under Part B ($ 1.1 billion) Effective January 1 2002, the US Congress extended Medicare coverage to include MNT to beneficiaries with diabetes or renal diseases. The Centers for Medicare and Medicaid Services (CMS) established the duration and frequency for the MNT based on published reports or generally accepted protocols (for example, protocols suggested by the ADA). The number of hours covered by Medicare is 3 hours for the initial MNT and 2 hours for a follow-up MM. In 2002, a Medicare coverage policy was made to define the Physician's Current Procedural Terminology (CPT) codes 97802, 97803, and 97804 for MNT.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.3104-3110
• /
• 2011

This paper describes how to ensure safety of train by guaranteeing stable and continuous communication in RF-CBTC. CBTC System uses the wireless communication between onboard and wayside so that safety of wireless communication is the most important. Losing the position of train causes vital problem of train service. By losing the position of train, the other trains are blocked in the block and the train move by emergency mode so headway and safety cannot guaranteed. Therefore, safety is ensured by redundancy of wireless equipment. One of the ways to make redundancy is redundancy of equipment. However, the redundancy of equipment spends a lot of money to avoid interference in limited place like underground. Continuous communication is guaranteed by means of redundancy of wireless communication coverage to solve the problems even though one of the equipment is broken.

• ETRI Journal
• /
• 제35권6호
• /
• pp.1144-1147
• /
• 2013

Dual-mode terminals (DMTs) equipped with cellular and WLAN interfaces have become popular in recent years. Users of DMTs can enjoy high-speed WLAN Internet access and wide area Internet access to cellular networks. However, a DMT may consume power inefficiently when discovering a WLAN with inherently limited service coverage. In this letter, we propose to use smart WLAN discovery (SWD) to minimize the power consumption required for WLAN discovery. To minimize the power consumption of a DMT, an SWD DMT activates its WLAN interface only when the DMT transfers data within the WLAN coverage area. The simulation results of SWD show an improved power-saving performance compared to previous WLAN discovery schemes.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2008년도 하계종합학술대회
• /
• pp.349-350
• /
• 2008

Average throughput estimation of EV-DO forward link is implemented on the basis of the serving coverage area per sector instead of time consuming and complicated Monte Carlo simulation. For the implementation of this analysis function in cell planning tool, $CellTREK^{(R)}$, developed by KT, both SNR vs. DRC mapping table and receiver sensitivity are suggested as the satisfying criteria to be satisfied above each threshold level simultaneously.

• 방송공학회논문지
• /
• 제7권1호
• /
• pp.10-20
• /
• 2002

지상파 DTV 방송 구역내의 음영지역을 보완하기 위하여 KBS 기술연구소에서는 DTV 중계기와 동일채널 중계기술을 연구하고 있다. 특히. 동일채널 중계기법은 주파수 자원을 재사용하여 서비스 범위를 확장할 수 있으나 ATSC DTV 시스템에 적용하기 위해서는 많은 제약이 따른다. 본 논문에서는 동일 채널 중계방식 중 단순 중계방식과 재생 중계방식을 실제 필드테스트를 통해서 비교하고. DTV 방송 시스템을 위한 동일 채널 중계기의 설치 조건과 활용 가능성에 대해서 분석한다.

• 전자통신동향분석
• /
• 제36권5호
• /
• pp.51-61
• /
• 2021

To reduce mobile network deployment costs and expand service coverage, mobile infrastructure sharing is becoming increasingly important. This paper introduces the concept and potential benefits of mobile infrastructure sharing as documented in the existing literature. Then, the current status of significant cases of mobile infrastructure sharing in major overseas countries is examined. Finally, sharing 5G infrastructure in rural areas in Korea is introduced. The Korean case is expected to complete national 5G coverage successfully without involving negative competition.

• 한국정보기술학회 영문논문지
• /
• 제10권2호
• /
• pp.73-81
• /
• 2020

The number of mobile devices roaming into a ubiquitous city (u-city) continues to rise as wireless systems have been widely deployed. The number of mobile devices also varies with time, and they tend to frequently change their locations. In addition, the available wireless access networks may belong to different domains, administrations, management, and internet service providers (ISPs). A fusion of overlapping heterogeneous wireless access networks (e.g., WiMax, Wi-Fi, LTE, etc.) serves the u-city in order to reach different coverage. In this context, technical challenges arise in mobility management for heterogeneous networks to realize their potential coverage and capacity benefits. This paper deals with the analysis of a decentralized mobility management support for u-City wireless network infrastructure. This scheme takes advantage of the features of the fully-distributed model of networked-based mobility management protocol to alleviate and realize the ubiquitous requirements of a u-City.

• 한국통신학회논문지
• /
• 제30권1A호
• /
• pp.76-83
• /
• 2005

본 논문은 Diameter 기반 AAA 시스템에서 Mobile-lP 응용과 연동하는 선불 서비스의 설계 및 구현에 대하여 기술하였다. 선불 서비스 기능은 Diameter의 Credit-Control 응용에 기반 하였으며, Credit-Control 응용은 기존의 RADIUS 과금 방식이나 Diameter 베이스 프로토콜의 과금 방식이 지원하지 않는 선불 과금 서비스를 제공하기 위한 응용 기능이다. 실시간 선불 서비스 기능은 실시간 서비스 비용 결정과 서비스를 제공하기 위한 사용자의 계정 잔액 확인 절차 등과 같은 추가의 기능들을 요구한다. 본 논문에서는 위와 같은 추가의 기능들을 지원할 수 있도록, Mobile-lP 응용 서비스인 Diameter Mobile-lP 응용과 연동하는 Diameter Credit-Control 응용의 설계와 구현에 대하여 기술한다.