• 한국전자통신학회논문지
• /
• 제14권5호
• /
• pp.817-824
• /
• 2019

OFDM(Orthogonal Frequency Division Multiplexing) 전송 신호의 PAPR (Peak-to-Average Power Ratio)을 효과적으로 감소시키기 위하여 클리핑 잡음 (Clipping Noise)을 이용한 적응적 톤 삽입 (Adaptive Tone Reservation; ATR) 기법을 제안한다. 제안된 ATR 기법은 기존 TR 방법에서의 복잡도 문제를 개선하기 위해, IFFT (Inverse Fast Fourier Transform) 출력 가운데 임계 진폭값 보다 큰 신호들을 클리핑 하는 과정, 클리핑된 신호에 대해 클리핑 잡음을 계산 후 주파수 영역 클리핑 잡음의 심벌 중에서 가장 큰 전력이 할당된 톤을 추출하는 과정, 추출된 톤을 예약하여 PAPR을 감소하는 과정의 총 3단계로 구성된다. 모의실험 결과, 제안된 ATR 기법은 톤 예약이 가능한 최적의 톤을 클리핑 잡음을 이용하여 추출함으로써 기존 TR 방법의 계산량을 획기적으로 줄이면서도 성능이 최적의 TR 방법에 근접한 것을 보여준다.

• ETRI Journal
• /
• 제24권4호
• /
• pp.299-310
• /
• 2002

This paper describes an integrated network management framework for providing point-to-multipoint reservation service (PMRS) in an ATM network. There are two major issues confronting the network service provider in relation to this service: one is to rapidly confirm the acceptability of the subscriber's reservation at subscription time, and the other is to punctually activate the reserved point-to-multipoint service. To meet these requirements, we developed a service provision model (SPM) and a network resource model of a bandwidth allocation timetable (BATT). We propose a point-to-multipoint routing algorithm composed of ordering and backtracking procedures, which can find the best branch point under the complex network topology and can add more destinations to the existing point-to-multipoint route. We demonstrate the feasibility of the SPM, the BATT, and the point-to-multipoint routing algorithm by implementing our schemes and analyzing their performance under the operational ATM network of KT(Korea Telecom).

• 한국환경생태학회지
• /
• 제35권2호
• /
• pp.181-192
• /
• 2021

본 연구는 탐방예약제(Visitor reservation system: VRS) 도입의 필요성이 거론되고 있는 무등산국립공원의 서석대 탐방구간(Seoseokdae Trail Section: STS)을 대상으로 VRS에 대한 탐방객의 인식을 조사하기 위해 시행되었다. 데이터는 2019년 5월 중 STS를 이용하는 248명의 탐방객을 대상으로 설문조사를 통해 수집되었다. 전 응답자의 86.9%가 STS에서의 전반적 탐방경험의 질을 높게 평가하였다. 또한 43.0%의 응답자가 VRS에 대하여 알고 있었으며 정보입수 경로는 인터넷이 49.7%로 가장 높은 비율을 차지하였으며, 주변인(18.4%), 방송매체(17.7%) 순으로 높게 나타났다. 전 응답자의 69.9%가 VRS 시행이 STS 관리개선에 효과가 있을 것으로 생각한 반면, 79.3%의 응답자가 VRS의 운영에 따르는 '번거로운 예약절차'가 문제가 있다고 인식하였으며, '인터넷 친숙성에 따른 불공평성'(78.7%), '자유로운 탐방기회 박탈'(76.3%) 순으로 문제가 있다고 생각하였다. VRS 시행에 대한 지지도는 고연령층, 기혼자, 고학력층, 고빈도 STS 방문경험자, 광주시 거주자, 1인 방문객이 상대그룹보다 낮은 것으로 나타났다. 'VRS에 대한 지식정도'와 'VRS 운영에 따르는 문제에 대한 인식정도'는 'VRS 시행에 대한 지지도'에 부(-)의 영향, 'VRS의 관리 효과성'은 'VRS 시행에 대한 지지도'에 정(+)의 영향이 있는 것으로 각각 조사되었다.

• 인터넷정보학회논문지
• /
• 제8권1호
• /
• pp.1-14
• /
• 2007

멀티미디어 트래픽의 전송 중에 핸드오프가 발생하면 멀티미디어 트래픽의 QoS가 지연 및 손실에 의하여 영향 받기 때문에, 정지 상태에서의 경우와 대등한 QoS를 유지하기 위해서는 효율적인 자원 예약 및 할당 방안이 필요하다. 본 논문에서는 이동 멀티미디어 망에서 이동 단말기의 이동 방향 추정에 근거하여 자원을 예약하고, 멀티미디어 트래픽을 전송하는 핸드오프 방법을 제안한다. 이 기법은 퍼지 다기준 의사 결정 방법에 근거한 MT 추적을 적용한다. 이 방법에서 기존의 수신신호세기 이외에 MT와 기지국간의 거리, 이동 방향, 이전 위친 등의 다수의 부정확한 위치 결정 파리미터를 사용 함으로서 추정의 정확성을 증가시킨다. 이 위치 정보에 근거하여 이동 방향을 결정하고, 이를 이용하여 자원을 예약한다. 실시간 세션의 핸드오프 요구는, 이동 방향 정보에 근거하여 동적으로 예약되고 할당된다. 제안된 방법의 성능을 시뮬레이션에 의해 분석한다.

• 한국치위생학회지
• /
• 제18권5호
• /
• pp.751-761
• /
• 2018

Objectives: The purpose of this study was to identify factors affecting choice of treatment hospital (i.e., determinants) and satisfaction with the treatment hospital, and to provide a more satisfactory and high-quality medical service for orthodontic patients. Methods: A questionnaire survey was conducted for approximately 1 month beginning in August 2017, involving patients who visited orthodontic dentistry clinics in Seoul and Gyeonggi-do. Multiple regression analysis was performed on the results to examine factors that affected satisfaction with orthodontic treatment. Results: The determinant of dental clinics was 3.90 points overall; hospital environment and facilities were highest at 4.05, followed by dental hygienist at 3.99, and dentist at 3.97. Factors influencing satisfaction with orthodontic treatment were positively influenced by dentists (p<0.01), medical procedures (p<0.01) and medical expenses (p<0.01). Conclusions: It is important to provide comfort and convenience to patients by simplifying hospital facility management, reception, and reservation procedures.

• ETRI Journal
• /
• 제29권1호
• /
• pp.116-119
• /
• 2007

In this letter, we design a collision resolution protocol for optical burst switching ring networks to avoid burst collision. We define the offset time condition for no burst transmission collision and manage the free time list of nodes for no burst reception collision. In order to improve the throughput, we use a fiber delay line, void-filling, and void-compression. This protocol does not require any additional procedures for bandwidth reservation such as centralized assignment of bandwidth, lightpath setup of WDM ring networks, or token capturing for the burst transmission. The simulation results show that the proposed protocol can achieve high throughput while saving 70% of wavelengths when compared to round robin with random selection, round robin with persistent, and round robin with non-persistent with only destination delay.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제7권11호
• /
• pp.2636-2656
• /
• 2013

To improve the cooperative efficiency of node cooperation and multiple access performance for multihop wireless networks, a priority-differentiated cooperative medium access control protocol with contention resolution (CRP-CMAC) is proposed. In the protocol, the helper selection process is divided into the priority differentiation phase and the contention resolution phase for the helpers with the same priority. A higher priority helper can choose an earlier minislot in the priority differentiation phase to send a busy tone. As a result, the protocol promptly selects all the highest priority helpers. The contention resolution phase of the same priority helpers consists of k round contention resolution procedures. The helpers that had sent the first busy tone and are now sending the longest busy tone can continue to the next round, and then the other helpers that sense the busy tone withdraw from the contention. Therefore, it can select the unique best helper from the highest priority helpers with high probability. A packet piggyback mechanism is also adopted to make the high data rate helper with packet to send transmit its data packets to its recipient without reservation. It can significantly decrease the reservation overhead and effectively improve the cooperation efficiency and channel utilization. Simulation results show that the maximum throughput of CRP-CMAC is 74%, 36.1% and 15% higher than those of the 802.11 DCF, CoopMACA and 2rcMAC protocols in a wireless local area network (WLAN) environment, and 82.6%, 37.6% and 46.3% higher in an ad hoc network environment, respectively.

• 한국정보처리학회논문지
• /
• 제4권6호
• /
• pp.1601-1614
• /
• 1997

본 논문에서는 ATM-LAN 환경의 MOD 서버들로부터 클라이언트들에게 프레임 기반의 CM(Continuous Media) 데이터 스트림을 전송하기 위한 기술들을 제안한다. 여기서 프레임이란 CM의 디스플레이 단위를 의미한다. 세부적으로는 수송 계층과 IP 계층의 개입없이 애플리케이션과 AAL이 직접적으로 접속함으로써 ATM-Specific한 native ATM 서비스를 적용한다. 또한 네비게이션 서버를 통한 투명한 브라이징 메카니즘, 서버와 클라이언트들간의 PVC를 통한 세션 설정 과정, 애플리케이션과 AAL과 QoS 협상 및 예약 과정, MIU 사이즈를 초과하는 프레임들에 대한 쪼갬/붙임 알고리즘 등을 제안하고 실험 결과를 제시한다.

• 한국경영과학회지
• /
• 제26권3호
• /
• pp.21-37
• /
• 2001

Riding on the wave of the information technology revolution, a slow of internet venture businesses (IVB) came into being. Hence, one of the recent developments in Korean capital market has been the proliferation of IVB, which is in accordance with the worldwide trend of ‘new economy’. Although the fair valuation is crucial for the nourishment of IVB, it is difficult to apply traditional valuation methods to these firms without reservation. It is due to the facts that most venture firms have little records of performance, grow unprecedently fast, and have highly uncertain future. The main purpose of this study is to suggest performance evaluation system of IVB and to develop KPE (Key Performance Indicators). Our empirical study is based upon Kaplan & Norton’s Balance Scorecard (BSC) approach. Specifically, our research has been conducted by the following two subsequent procedures: Firstly, seven internet venture firms have been selected and their executives have been interviewed by FGI(Focus Group Interview) method. Based upon these results, performance indicators have been developed. Secondly, by using the above mentioned BSC items (i.e., financial perspective, customer perspective, internal perspective and innovation & learning perspective), questionnaires have been constructed and sent to IVB through e-mail as well as over the Fax. Among the collected 110 samples, reliable 106 samples have been used to build BSC model and to draw our conclusion. In the future study, it would be much better to consider the role of strategy in IVB and the causal relationship among Key Performance Indicators of BSC.

• International Journal of Internet, Broadcasting and Communication
• /
• 제14권2호
• /
• pp.36-39
• /
• 2022

Medical tourism is recognized as a high value-added industry due to its longer stay and more useful costs than general tourism, and is growing rapidly around the world, especially in Asia. In addition, medical tourism is a new form of tourism that combines medical services with tourism activities such as recreation, leisure, and cultural activities, nowadays, medical tourism is emphasizing the combination of medical and tourism. Although Korea medical system and clinic have excellent medical equipment and infrastructure, it is not consistent with policy support and legislation. That have make it difficult for consumers to choose clinics for medical tourism. Therefore, it is necessary to provide customized information to the clinics that consumers want to match each other's services. In particular, it is aimed at consumers with simple procedures and cosmetic purposes, especially at small hospitals. In this paper, we propose a customized service platform that matches users seeking clinics and also medical tourism. Also we can easy to reservation clinic for medical tour.