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LTE/WLAN 이종망 환경에서 퍼지제어와 정책적 다기준 의사결정법을 이용한 적응적 VHO 방안 연구
이인환,김태섭,조성호,Lee, In-Hwan,Kim, Tae-Sub,Cho, Sung-Ho 한국정보처리학회 2010 정보처리학회논문지 C : 정보통신,정보보안 Vol.17 No.3
차세대 이동통신 시스템에서는 3세대 진화망인 LTE(long-Term Evolution), WiMAX/WiBro, 차세대 WLAN등 다양한 무선 접속 기술이 All-IP 기반의 핵심망을 중심으로 통합되는 형태로 발전하고 있다. 이러한 발전에 따라 중첩된 다양한 무선 이종망 환경에서 최적의 조건을 제공하는 망으로의 접속을 제공하는 수직적 핸드오버가 필요하다. 그러나 현재까지는 각각의 네트워크가 독자적 서비스 제공을 위해 독립적인 무선자원관리 기능을 제공하여 왔으므로, 이종망 환경에서의 다양한 네트워크를 끊김없이 서비스를 제공하기 위해서는 개별 네트워크의 무선자원들을 통합적으로 관리하여 최적의 서비스를 제공할 수 있어야 할 것이다. 최근 이러한 무선 이종망 환경에서의 문제점을 해결하기 위해 적응적이동성을 위한 범용링크계층(GLL)과 통합무선자원관리(CRRM) 방식의 개념이 도입되고 있다. 본 논문에서는 LTE와 WLAN 사이에서의 효율적인 수직적 핸드오버를 위한 범용링크계층을 기반으로 정책기반과 다기준 의사결정법(MCDM)을 혼합한 수직적 핸드오버 알고리즘을 제안하고, 퍼지 로직 제어기(FLC)를 이용하여 핸드오버 시점을 적응적으로 결정하는 방안을 제안한다. 시뮬레이션 연구 결과 본 논문에서 제안하는 수직적 핸드오버 기법은 수신신호의 세기를 기반으로하는 방법과 MCDM 만을 사용하는 방법에 비해 데이터 처리량, 핸드오버 성공확률, 서비스 사용비용 그리고 핸드오버 시도 횟수 측면에서 우수한 성능을 보였다. For the next generation mobile communication system, diverse wireless network techniques such as beyond 3G LTE, WiMAX/WiBro, and next generation WLAN etc. are proceeding to the form integrated into the All-IP core network. According to this development, Beyond 3G integrated into heterogeneous wireless access technologies must support the vertical handover and network to be used of several radio networks. However, unified management of each network is demanded since it is individually serviced. Therefore, in order to solve this problem this study is introducing the theory of Common Radio Resource Management (CRRM) based on Generic Link Layer (GLL). This study designs the structure and functions to support the vertical handover and propose the vertical handover algorithm of which policy-based and MCDM are composed between LTE and WLAN systems using GLL. Finally, simulation results are presented to show the improved performance over the data throughput, handover success rate, the system service cost and handover attempt number.
IEEE802.16j 기반의 2-홉 셀룰러 중계시스템에서 하향링크 접근영역과 중계영역에 대한 최적 무선자원 할당방법 연구
이인환 ( In Hwan Lee ),김세진 ( Se-jin Kim ),조성호 ( Sung Ho Cho ) 한국인터넷정보학회 2010 인터넷정보학회논문지 Vol.11 No.3
본 논문에서는OFDMA-TDD 구조를 갖는 IEEE802.16j 기반의 2-홉 셀룰러 중계시스템에서 non-transparent 방식의 무선 중계기를 이용하여 서비스 영역을 확장할 때, 시스템 전송률 및 하향링크 접근영역(Access zone)과 중계영역(Relay zone)에 대한 최적 무선자원 할당방법을 연구한다. 분석을 위해 먼저 non-transparent 방식의 MAC (Media Access Control) 프레임 구조를 알아보고, 접근영역과 중계영역에서 단말과 중계기 등의 네트워크 구성요소들에 대한 간섭요소들을 조사한다. 모의실험을 통하여 기지국과 중계기의 거리에 따라 확장되는 2-홉 셀 커버리지 크기와 전송률을 분석하고, 분석된 결과를 이용하여 하향링크 접근영역과 중계영역에 대한 최적 무선자원 할당량을 제시한다. In this paper, we evaluate the system throughput and the method of optimal wireless resource allocation for the access zone (AZ) and relay zone (RZ) in downlink when the cell coverage is extended using the non-transparent Relay Station (RS) in a 2-hop cellular relay system based on IEEE802.16j, which uses the OFDMA-TDD structure. For the analyses, we first introduce the MAC (Media Access Control) frame structure in the non-transparent mode, then we investigate the interfering elements in both AZ and RZ for the network devices such as the Mobile Station (MS) and RS. Through computer simulation, we analyze the cell coverage extension and system throughput in terms of the distance between Base Station (BS) and RS, then we present the amount of the optimal allocation of wireless resource for the AZ and RZ in downlink using our results.
박성욱,이인환,정우상,문상관,박정미,고창남,조기호,김영석,배형섭,Park, Seong-Uk,Lee, In-Whan,Jung, Woo-Sang,Moon, Sang-Kwan,Park, Jung-Mi,Ko, Chang-Nam,Cho, Ki-Ho,Kim, Young-Suk,Bae, Hyung-Sup 대한중풍순환신경학회 2008 대한중풍.순환신경학회지 Vol.9 No.1
Objectives : Metabolic syndrome (MetS) is associated with increasing risk of cardiovascular morbidity and mortality but the risk of stroke associated with the MetS is less well established. The objective of this study was to evaluate the prevalence of MetS in stroke patients. Methods : We analyzed the data of 806 patients with acute ischemic stroke from Hanbang Stroke Registry supported by the Ministry of Science and Technology of Korea. Subjects' enrollment was done in the oriental medical hospitals of 4 universities located in the metropolitan region from April 2007 to August 2008. We analyzed all registered data and evaluated the prevalence of MetS and specific components of MetS. Results : The prevalence of MetS in stroke patients according to American Heart Association/National Heart Lung and Blood Institute (AHA/NHLBI) criteria was 59.6%. The prevalence according to the International Diabetes Federation (IDF) criteria was 41.6%. The prevalence of female patients was higher than that of male patients (71.8% vs 51% by AHA/NHLBI criteria; 61.7% vs 27.7% by IDF criteria). The prevalence of central obesity, low HDL cholesterol and hypertension was higher in female patients. There was no significant relationship between MetS and stroke subtype. Conclusions : This work gives us the basic data on the association between MetS and risk of stroke. There should be the prospective cohort studies to evaluate MetS and the risk of stroke.
우상구(Sang Gu Woo),김호찬(Ho-Chan Kim),이경창(Kyoung-Chang Lee),조해용(Hae Yong Cho),이인환(In Hwan Lee) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
Many kinds of robots or machines have to help people safely through interacting with surrounding environments. In this regards, they have to get environmental data from outside using diverse sensors. Among the sensors, tactile sensor is important because of its ability of getting information such as surface texture and force by mechanical contact. In this research, simple tactile sensor was proposed using direct writing of pressure sensitive material as well as layered fabrication of PDMS. The pressure sensitive material was mixed with PDMS and MWCNTs. The body of the sensor was fabricated using layered fabrication. And among the layers the pressure sensitive materials were dispensed using direct writing. We examined the line fabrication characteristics of the pressure sensitive material according to the nozzle dispensing conditions. A simple 4 x 4 array flexible tactile sensor was fabricated successfully using proposed process.
적층조형과 직접주사방식을 결합한 광경화성 수지 기반의 신축성 촉각센서의 제작
우상구(Sang Gu Woo),이인환(In Hwan Lee),김호찬(Ho-Chan Kim),이경창(Kyung Chang Lee),조해용(Hae-Yong Cho) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.2
Many kinds of robots and machines have been developed to replace human laborin industrial and medical fields, as well as domestic life. In these applications, the device sneed to obtain environmental data using diverse sensors. Among such sensors, the tactile sensor is important because of its ability to get information regarding surface texture and force through the use of mechanical contact. In this research, a simple tactile sensor was developed using the direct writing of pressure sensitive material and layered fabrication of photocurable material. The body of the sensor was fabricated using layered fabrication, and pressure sensitive materials were dispensed between the layers using direct writing. We examined the line fabrication characteristics of the pressure sensitive material according to nozzle dispensing conditions. A simple 4 x 4 array flexible tactile sensor was successfully fabricated using the proposed process.