• Title/Summary/Keyword: local wireless communication

Search Result 382, Processing Time 0.035 seconds

Analysis of Acceleration and Deceleration on High Performance Train for A Metropolitan Rapid Transit System (대피선 최소화를 고려한 광역·도시철도 급행화를 위한 고성능 열차 가감속도 분석)

  • KO, Kyeong Jun;KIM, Jung Tai;KIM, Moo Sun;JANG, Dong Uk;HONG, Jae Sung;RYU, Sang Hwan;JUNG, Jong Deok
    • Journal of Korean Society of Transportation
    • /
    • v.33 no.6
    • /
    • pp.564-574
    • /
    • 2015
  • As shown by the popularity of the rapid train in the Seoul Metro Line No. 9, the demand for the rapidization of the metro transit has been continuously increased. However, it needs tremendous cost to construct new additional infrastructures to the existing line for the rapidization. In order to overcome the problem, utilizing the existing infrastructures such as crossing tracks as railroad sidetracks can be considered to be a good method of reducing the cost. In this case, there is a way exploiting the existing train as an express train and the advanced train, which increases both acceleration and deceleration, as a local train, but achievable acceleration and deceleration have not been analyzed rigorously. In this paper, we analyze feasible ranges and optimal values of both acceleration and deceleration of the advanced train analytically when we consider the rapidization of the metro transit utilizing the existing infrastructures and verify the results in Seoul Metro Line No. 3. Simulation results show ranges and optimal values of achievable acceleration and deceleration exist when minimum gap between an express train and a local train is smaller than 40 seconds.

The IEEE 802.15.4e based Distributed Scheduling Mechanism for the Energy Efficiency of Industrial Wireless Sensor Networks (IEEE 802.15.4e DSME 기반 산업용 무선 센서 네트워크에서의 전력소모 절감을 위한 분산 스케줄링 기법 연구)

  • Lee, Yun-Sung;Chung, Sang-Hwa
    • Journal of KIISE
    • /
    • v.44 no.2
    • /
    • pp.213-222
    • /
    • 2017
  • The Internet of Things (IoT) technology is rapidly developing in recent years, and is applicable to various fields. A smart factory is one wherein all the components are organically connected to each other via a WSN, using an intelligent operating system and the IoT. A smart factory technology is used for flexible process automation and custom manufacturing, and hence needs adaptive network management for frequent network fluctuations. Moreover, ensuring the timeliness of the data collected through sensor nodes is crucial. In order to ensure network timeliness, the power consumption for information exchange increases. In this paper, we propose an IEEE 802.15.4e DSME-based distributed scheduling algorithm for mobility support, and we evaluate various performance metrics. The proposed algorithm adaptively assigns communication slots by analyzing the network traffic of each node, and improves the network reliability and timeliness. The experimental results indicate that the throughput of the DSME MAC protocol is better than the IEEE 802.15.4e TSCH and the legacy slotted CSMA/CA in large networks with more than 30 nodes. Also, the proposed algorithm improves the throughput by 15%, higher than other MACs including the original DSME. Experimentally, we confirm that the algorithm reduces power consumption by improving the availability of communication slots. The proposed algorithm improves the power consumption by 40%, higher than other MACs.

Dual-Band Six-Port Direct Conversion Receiver with I/Q Mismatch Calibration Scheme for Software Defined Radio (Software Defined Radio를 위한 I/Q 부정합 보정 기능을 갖는 이중 대역 Six-Port 직접변환 수신기)

  • Moon, Seong-Mo;Park, Dong-Hoon;Yu, Jong-Won;Lee, Moon-Que
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.21 no.6
    • /
    • pp.651-659
    • /
    • 2010
  • In this paper, a new six-port direct conversion receiver for high-speed multi-band multi-mode wireless communication system such as software defined radio(SDR) is proposed. The designed receiver is composed of two CMOS four-port BPSK receivers and a dual-band one-stage polyphase filter for quadrature LO signal generation. The four-port BPSK receiver, implemented in 0.18 ${\mu}m$ CMOS technology for the first time in microwave-band, is composed of two active combiners, an active balun, two power detector, and an analog decoder. The proposed polyphase filter adopt type-I architecture, one-stage for reduction of the local oscillator power loss, and LC resonance structure instead of using capacitor for dual-band operation. In order to extent the operation RF bandwidth of the proposed six-port receiver, we include I/Q phase and amplitude calibration scheme in the six-port junction and the power detector. The calibration range of the phase and amplitude mismatch in the proposed calibration scheme is 8 degree and 14 dB, respectively. The validity of the designed six-port receiver is successfully demonstrated by modulating M-QAM, and M-PSK signal with 40 Msps in the two-band of 900 MHz and 2.4 GHz.

Bicycle Riding-State Recognition Using 3-Axis Accelerometer (3축 가속도센서를 이용한 자전거의 주행 상황 인식 기술 개발)

  • Choi, Jung-Hwan;Yang, Yoon-Seok;Ru, Mun-Ho
    • Journal of the Institute of Electronics Engineers of Korea SC
    • /
    • v.48 no.6
    • /
    • pp.63-70
    • /
    • 2011
  • A bicycle is different from vehicles in the structure that a rider is fully exposed to the surrounding environment. Therefore, it needs to make use of prior information about local weather, air quality, trail road condition. Moreover, since it depends on human power for moving, it should acquire route property such as hill slope, winding, and road surface to improve its efficiency in everyday use. Recent mobile applications which are to be used during bicycle riding let us aware of the necessity of development of intelligent bicycles. This study aims to develop a riding state (up-hill, down-hill, accelerating, braking) recognition algorithm using a low-power wrist watch type embedded system which has 3-axis accelerometer and wireless communication capability. The developed algorithm was applied to 19 experimental riding data and showed more than 95% of correct recognition over 83.3% of the total dataset. The altitude and temperature sensor also in the embedded system mounted on the bicycle is being used to improve the accuracy of the algorithm. The developed riding state recognition algorithm is expected to be a platform technology for intelligent bicycle interface system.

Research on Classification of Monitoring Items for the Integrated Management of the Underground Facilities (지하시설물 통합관리를 위한 모니터링 항목 분류에 관한 연구)

  • Kim, Jung-Hoon;Min, Kyung-Ju;Lee, Mi-Sook;Lim, Si-Yeong
    • Spatial Information Research
    • /
    • v.18 no.1
    • /
    • pp.19-26
    • /
    • 2010
  • It is important to manage the underground facilities efficiently because they are directly related to the convenience and safety of citizens. But the fact that the different agencies take on a role of managing the underground facilities respectively makes it impossible. So Korean government has exerted great efforts to solve this problem through several projects. Korean government expects that the ubiquitous technologies such as sensor and wireless communication in the domain of the underground facilities management will be useful. It is main duty of u-City Management Center to monitor several situations about the underground facilities using ubiquitous technologies. But there is no consensus about what concrete situations it has to monitor even though u-cities under construction. Because local governments or related companies are in charge of carrying out these roles yet, there is no legal basis on which to do these tasks by the center. And it is needed to develop new technologies for u-services efficiently. Because technologies for u-service are vast, various and converged, so it necessary to develop them according to priority or in cooperation with other developers. In this paper, we classify the monitoring items for each facility which were investigated by a recent research. It is expected to make use of defining the role of the center and developing technologies with u-service.

Update Frequency Cache Consistency for Reducing Wait Time in Mobile Computing (이동 컴퓨팅 환경에서 대기 시간을 감소시키는 갱신 빈도 캐쉬 일관성 기법)

  • Lee, Chan-Seob;Kim, Dong-Hyuk;Baek, Joo-Hyun;Choi, Eui-In
    • The KIPS Transactions:PartD
    • /
    • v.9D no.6
    • /
    • pp.1017-1024
    • /
    • 2002
  • According as mobile computing environment is generalized by development of wireless networking technology and communication device, mobile host uses local cache for extensibility and early response time. and reduction of limited bandwidth. This time, between mobile host and mobile support station cache need consistency interested person of done data accordingly much techniqueses propose. Existent consistency techniques because detection based techniqueses are used mainly and broadcast periodic invalid message considering frequent disconnection. However, these techniqueses increase abort step through increase or delay of transmission message number by accuracy examination of data. Therefore, because mobile host deletes cached data, and extensity are decreased. Techniques that is proposed in this paper did to perform refering update frequency about object that page request or when complete update operation happens to solve these problem. Therefore, have advantage that response is fast because could run write intention declaration or update by update frequency electively asynchronously when update operation consists and abort step decreases. Also, improved extensity running delete or propagation electively according to update frequency about periodic invalid message gone since disconnection.

Design of pHEMT channel structure for single-pole-double-throw MMIC switches (SPDT 단일고주파집적회로 스위치용 pHEMT 채널구조 설계)

  • Mun Jae Kyoung;Lim Jong Won;Jang Woo Jin;Ji, Hong Gu;Ahn Ho Kyun;Kim Hae Cheon;Park Chong Ook
    • Journal of the Korean Vacuum Society
    • /
    • v.14 no.4
    • /
    • pp.207-214
    • /
    • 2005
  • This paper presents a channel structure for promising high performance pseudomorphic high electron mobility transistor(pHEMT) switching device for design and fabricating of microwave control circuits, such as switches, phase shifters, attenuators, limiters, for application in personal mobile communication systems. Using the designed epitaxial channel layer structure and ETRI's $0.5\mu$m pHEMT switch process, single pole double throw (SPDT) Tx/Rx monolithic microwave integrated circuit (MMIC) switch was fabricated for 2.4 GHz and 5 GHz band wireless local area network (WLAN) systems. The SPDT switch exhibits a low insertion loss of 0.849 dB, high isolation of 32.638 dB, return loss of 11.006 dB, power transfer capability of 25dBm, and 3rd order intercept point of 42dBm at frequency of 5.8GHz and control voltage of 0/-3V These performances are enough for an application to 5 GHz band WLAN systems.

Different Heterogeneous IoT Data Management Techniques for IoT Cloud Environments (IoT 클라우드 환경을 위한 서로 다른 이기종의 IoT 데이터 관리 기법)

  • Cho, Sung-Nam;Jeong, Yoon-Su
    • Journal of Convergence for Information Technology
    • /
    • v.10 no.12
    • /
    • pp.15-21
    • /
    • 2020
  • Although IoT systems are used in a variety of heterogeneous environments as cloud environments develop, all IoT devices are not provided with reliable protocols and services. This paper proposes an IoT data management technique that can extend the IoT cloud environment to an n-layer multi-level structure so that information collected from different heterogeneous IoT devices can be efficiently sorted and processed. The proposed technique aims to classify and process IoT information by transmitting routing information and weight information through wireless data link data collected from heterogeneous IoT devices. The proposed technique not only delivers information classified from IoT devices to the corresponding routing path but also improves the efficiency of IoT data processing by assigning priority according to weight information. The IoT devices used in the proposed technique use each other's reliable protocols, and queries for other IoT devices locally through a local cloud composed of hierarchical structures have features that ensure scalability because they maintain a certain cost.y channels of IoT information in order to make the most of the multiple antenna technology.

Analysis of Driving and Environmental Impacts by Providing Warning Information in C-ITS Vehicles Using PVD (PVD를 활용한 C-ITS 차량 내 경고정보 제공에 따른 주행 및 환경영향 분석)

  • Yoonmi Kim;Ho Seon Kim;Kyeong-Pyo Kang;Seoung Bum Kim
    • The Journal of The Korea Institute of Intelligent Transport Systems
    • /
    • v.22 no.5
    • /
    • pp.224-239
    • /
    • 2023
  • C-ITS (Cooperative-Intelligent Transportation System) refers to user safety-oriented technology and systems that provide forward traffic situation information based on a two-way wireless communication technology between vehicles or between vehicles and infrastructure. Since the Daejeon-Sejong pilot project in 2016, the C-ITS infrastructure has been installed at various locations to provide C-ITS safety services through highway and local government demonstration projects. In this study, a methodology was developed to verify the effectiveness of the warning information using individual vehicle data collected through the Gwangju Metropolitan City C-ITS demonstration project. The analysis of the effectiveness was largely divided into driving behavior impact analysis and environmental analysis. Compliance analysis and driving safety evaluation were performed for the driving impact analysis. In addition, to supplement the inadequate collection of Probe Vehicle Data (PVD) collected during the C-ITS demonstration project, Digital Tacho Graph ( DTG ) data was additionally collected and used for effect analysis. The results of the compliance analysis showed that drivers displayed reduced driving behavior in response to warning information based on a sufficient number of valid samples. Also, the results of calculating and analyzing driving safety indicators, such as jerk and acceleration noise, revealed that driving safety was improved due to the provision of warning information.

E-Commerce in the Historical Approach to Usage and Practice of International Trade ("무역상무(貿易商務)에의 역사적(歷史的) 어프로치와 무역취인(貿易取引)의 전자화(電子化)")

  • Tsubaki, Koji
    • THE INTERNATIONAL COMMERCE & LAW REVIEW
    • /
    • v.19
    • /
    • pp.224-242
    • /
    • 2003
  • The author believes that the main task of study in international trade usage and practice is the management of transactional risks involved in international sale of goods. They are foreign exchange risks, transportation risks, credit risk, risk of miscommunication, etc. In most cases, these risks are more serious and enormous than those involved in domestic sales. Historically, the merchant adventurers organized the voyage abroad, secured trade finance, and went around the ocean with their own or consigned cargo until around the $mid-19^{th}$ century. They did business faceto-face at the trade fair or the open port where they maintained the local offices, so-called "Trading House"(商館). Thererfore, the transactional risks might have been one-sided either with the seller or the buyer. The bottomry seemed a typical arrangement for risk sharing among the interested parties to the adventure. In this way, such organizational arrangements coped with or bore the transactional risks. With the advent of ocean liner services and wireless communication across the national border in the $19^{th}$ century, the business of merchant adventurers developed toward the clear division of labor; sales by mercantile agents, and ocean transportation by the steam ship companies. The international banking helped the process to be accelerated. Then, bills of lading backed up by the statute made it possible to conduct documentary sales with a foreign partner in different country. Thus, FOB terms including ocean freight and CIF terms emerged gradually as standard trade terms in which transactional risks were allocated through negotiation between the seller and the buyer located in different countries. Both of them did not have to go abroad with their cargo. Instead, documentation in compliance with the terms of the contract(plus an L/C in some cases) must by 'strictly' fulfilled. In other words, the set of contractual documents must be tendered in advance of the arrival of the goods at port of discharge. Trust or reliance is placed on such contractual paper documents. However, the container transport services introduced as international intermodal transport since the late 1960s frequently caused the earlier arrival of the goods at the destination before the presentation of the set of paper documents, which may take 5 to 10% of the amount of transaction. In addition, the size of the container vessel required the speedy transport documentation before sailing from the port of loading. In these circumstances, computerized processing of transport related documents became essential for inexpensive transaction cost and uninterrupted distribution of the goods. Such computerization does not stop at the phase of transportation but extends to cover the whole process of international trade, transforming the documentary sales into less-paper trade and further into paperless trade, i.e., EDI or E-Commerce. Now we face the other side of the coin, which is data security and paperless transfer of legal rights and obligations. Unfortunately, these issues are not effectively covered by a set of contracts only. Obviously, EDI or E-Commerce is based on the common business process and harmonized system of various data codes as well as the standard message formats. This essential feature of E-Commerce needs effective coordination of different divisions of business and tight control over credit arrangements in addition to the standard contract of sales. In a few word, information does not alway invite "trust". Credit flows from people, or close organizational tie-ups. It is our common understanding that, without well-orchestrated organizational arrangements made by leading companies, E-Commerce does not work well for paperless trade. With such arrangements well in place, participating E-business members do not need to seriously care for credit risk. Finally, it is also clear that E-International Commerce must be linked up with a set of government EDIs such as NACCS, Port EDI, JETRAS, etc, in Japan. Therefore, there is still a long way before us to go for E-Commerce in practice, not on the top of information manager's desk.

  • PDF