• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.5
• /
• pp.981-989
• /
• 1997

In this paper, the 5-element active phased array antennas coupled through slotline between elements are designed and fabricated. A recent studies on the active phased array antennas using the transmission line coupling which can be designed to provide strong coupling and the appropriate coupling phase. But this sturucture has limitation of expanding in two dimensions for planar active phased array antennas and distortion of the radiation pattern caused by coupling network. Thus our work proposes the slotline coupling structure asthe broadband coupling network for the active phased array antenna. In experiment, 5-elements active phased array antenas have steering range from -30.deg. to 20.deg. off broadside as the free-running frequencies of end elements are controlled. The overall results show that the proposed slotline coupling structure is suited for the coupling network in the actie phased array antenna system. And the proposed coupling structire solves the expansion problem and eliminates the distortion of the radiation pattern caused by the spurious radiation of the transmission line coupling network. Thus thiscan be expanded to two dimensional coupling network for the planar active phased array antenna system.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.11
• /
• pp.5214-5218
• /
• 2011

In this paper, bandwidth improvement of a series-fed two dipole array(STDA) antenna applicable for mobile communication base station antennas is studied. The proposed STDA antenna consists of two strip dipole antennas with different lengths which are connected directly trough a coplanar stripline(CPS). By adjusting the spacing between the two dipoles and the length of the second dipole, the bandwidth of the STDA can be enhanced. In addition, an integrated balun composed of a short-circuited microstrip line and a slot line is utilized to minimize the area required for a feeding part, and a broadband impedance matching is obtained by adjusting the feeding point. Based on the proposed antenna structure, an STDA antenna covering the frequency band ranging from 1.75 GHz to 2.7 GHz, which includes almost all the existing mobile communication frequency bands, with more than 5 dBi gain is designed and fabricated on an FR4 substrate with dielectric constant of 4.4 and thickness of 1.6mm, and experimentally tested. The fabricated antenna shows impedance bandwidth of 49%(1.7-2.8 GHz) for VSWR<2, a gain higher than 5.5 dBi, and a front-back ratio better than 12 dB.

• Proceedings of the Korea Society for Simulation Conference
• /
• 2002.05a
• /
• pp.125-129
• /
• 2002

실시간 운영체제(Real-Time Operating System: 이하 RTOS라 함) 개발환경에서 제공하는 도구 중에 하나인 RTOS 시뮬레이터는 타겟 하드웨어가 호스트에 연결되어 있지 않아도 호스트에서 응용프로그램의 개발과 디버깅을 가능하게 해주는 타겟 시뮬레이션 환경을 제공해 줌으로서, 개발자로 하여금 빠른 시간 내에 응용프로그램을 개발할 수 있도록 지원하며 하드웨어 개발이 완료되기 전에도 응용프로그램을 개발할 수 있게 해 준다. 그러한 이유로 현재 대부분의 상용 RTOS 개발환경에서는 RTOS 시뮬레이터를 제공하고 있다. 그러나 현재 상용 RTOS 시뮬레이터들은 대부분 RTOS의 기능적인 부분들만 호스트에서 동작하도록 구현되어 있어서 RTOS나 RTOS 응용프로그램이 실제 타겟에서 실행될 때의 실질적인 시간 추정이 불가능하다. 이러한 문제점은 실시간 시스템이 정해진 시간 내에 결과를 출력해야 하는 시스템임을 감안한다면 RTOS 시뮬레이터의 가장 큰 결점이 되기 때문에 실행시간 추정 기능을 가지면서 실용화도 가능한 RTOS 시뮬레이터가 필요하다. 본 연구에서는 이러한 문제점을 해결하여 RTOS와 RTOS 응용프로그램이 실제 타겟에서 처리될 때의 실행시간 추정이 가능하고 상용화가 가능한 기계 명령어 기반(machine instruction-based)의 RTOS 시뮬레이터를 연구 개발하였다. 나아가 실행시간의 주요 요소인 파이프라인과 캐쉬의 영향도 고려함으로서 실행시간 추정의 정확도를 향상시켰다 본 연구에서 사용된 RTOS는 한국전자통신연구원(ETRI)에서 2000년에 개발된 Q+이고, Q+가 동작하는 타겟 하드웨어는 ARM 계열의 StrongARM SA-110 마이크로프로세서와 21285 주제어기가 장착된 EBSA-285 보드이다. 측정하면서 수행하였다. 검증 결과 random 상태에서는 문헌자료에 부합되는 예측결과를 보여주었으나, intermediate와 constant 상태에서는 문헌보다 다소 낮은 속도를 보여주었다 이러한 속도차는 추후 현장 데이터를 수집하여 보다 실질적인 검증을 통하여 조정되어야 할 것으로 판단된다.지발광(1.26초)보다 구애발광(1.12초)에서 0.88배 감소하였고, 암컷에서 정지발광(2.99초)보다 구애발광(1.06초)에서 0.35배 감소하였다. 발광양상에서 발광주파수는 수짓의 정지발광에서 0.8 Hz, 수컷 구애발광에서 0.9 Hz, 암컷의 정지발광에서 0.3 Hz, 암컷의 구애발광에서 0.9 Hz로 각각 나타났다. H. papariensis의 발광파장영역은 400 nm에서 700 nm에 이르는 모든 영역에서 확인되었으며 가장 높은 첨두치는 600 nm에 있고 500에서 600 nm 사이의 파장대가 가장 두드러지게 나타났다. 발광양상과 어우러진 교미행동은 Hp system과 같은 결과를 얻었다.하는 방법을 제안한다. 즉 채널 액세스 확률을 각 슬롯에서 예약상태에 있는 음성 단말의 수뿐만 아니라 각 슬롯에서 예약을 하려고 하는 단말의 수에 기초하여 산출하는 방법을 제안하고 이의 성능을 분석하였다. 시뮬레이션에 의해 새로 제안된 채널 허용 확률을 산출하는 방식의 성능을 비교한 결과 기존에 제안된 방법들보다 상당한 성능의 향상을 볼 수 있었다., 인삼이 성장될 때 부분적인 영양상태의 불충분이나 기후 등에 따른 영향을 받을 수 있기 때문에 앞으로 이에 대한 많은 연구가 이루어져야할 것으로 판단된다.태에도 불구하고 [-wh]의미의 겹의문사는 병렬적 관계의 합성어가 아니라 내부구조를 지니지 않은 단순한 단어(minimal $X^{0}$

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.38 no.12
• /
• pp.1-9
• /
• 2001

In the APON(ATM Passive Optical Network), the transmission of the upstream traffic is based on a TDMA(Time Division Multiple Access) method that an OLT(Optical Line Termination) permits ONUs(Optical Network Units) sending cells by allocating time slots. Because the upstream is not a streaming mode, the cell synchronizer has to be operated in the burst mode. Also, the cell phase monitor is required to prevent collisions between cells which are transmitted by multiple ONUs through a single optical fiber. In this paper, a TDMA burst cell synchroniser is implemented with the FPGA(Field Programmable Gate Array) being used in the APON based on G.983.1 for transmitting upstream cells. It has two main functions which are the upstream data recovery and the phase monitoring. The former is to recover the upstream data and clock in the OLT by seeking the preamble which is the overhead of the upstream time slot and by aligning the phase of the bit and cell with the system clock. The latter is to provide the information to the ONU to compensate for the equalization delay by monitoring continuously the phase difference between adjacent cells to avoid the cell collision on the upstream.

• Koreanishche Zeitschrift fur Deutsche Sprachwissenschaft
• /
• v.6
• /
• pp.57-78
• /
• 2002

적용구문(Applikative Konstruktion)은 타동사 구문의 일종이며 적용동사(Applikatives Verb)는 두 가지 유형으로 나눌 수 있다 적용동사가 자동사에서 타동사화 된 경우면 자동사에서는 없던 직접 목적어를 위한 슬롯이 적용형태소(Applikativmarker)를 통해 생긴다. 타동사에서 적용형태소의 삽입을 통해 변화된 적용동사는 두 개의 직접목적어를 취할 수 있는 동사의 특징을 나타내거나, 동사의 논항구조를 재배열하는 기능을 가진다. '논항구조 재배열'(rearrangement of argument structure)의 가장 전형적인 예는 타동사의 주변적인 참여자(peripherer Partizipant)를 적용동사를 통해 격상(Promotion) 시키는 반면 핵심참여자(zentraler Partizipant)는 격하(Demotion) 되는 구문이다. 즉 비 적용구문의 주변적인 참여자가 적용구문에서는 핵심참여자로서 직접목적어(direktes Objekt)의 통사적 기능을 가지는 것이다. 이러한 현상은 세계 여러 나라 언어에서 찾아 볼 수 있는데 본 논문에서는 독일어, 유카텍마야어, 인도네시아어, 캄베라어를 연구대상으로 삼았으며 이들 각 언어에서 어떤 참여자관계(Partizipantenrelation)가 적용구문의 직접목적어로 표현될 수 있는가를 살펴보았다. 이들 언어에서는 장소(Lokation)>수혜자($Benfizi\"{a}r$) & 수취인(Rezipient) > 동반자(Komitativ) > 기구(Instrument) 등의 순서로 가능하다. 이 것을 페터슨(1999)의 연구결과와 종합하여 살펴보면 적용구문의 직접목적어로 나타날 수 있는 참여자들의 순서는 루라기(2000)에 소개된 참여자의 원인연쇄(Kausale Kette)의 역순과 거의 일치하는 것을 볼 수 있는데 제일 자주 나타나는 참여자를 그 순서대로 보면 다음과 같다: 수혜자($Benefizi\"{a}r$) & 수취인(Rezipient)<장소(Lokation)>동반자(Komitativ) & 기구(Instrument)> 원인(Ursache). 이러한 순서를 우리는 '적용성의 위계'($Applikativit\"{a}tshierarchie$)라 부를 수 있으며 이것을 가능한 많은 언어에 유효한 언어의 보편성 중의 하나가 될 수 있다는 가설을 제기해 본다.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.10
• /
• pp.110-118
• /
• 2003

The paper describes a design process of the connection control function that performs overall procedures of optical network control system in the Next Generation - Synchronous Digital Hierarchy (NG-SDH) based transport system. Here, the NG-SDH means a new SDH technology that could perform automatic connection control with a granularity of VC-3 (about 50M) or VC-4 (about 150M) according to the increase and decrease of traffic, which is different from the existing technology that could perform connection control only with a granularity of a physical SDH link (STM-l, STM-4, STM-16, STM-64, STM-256 etc). The NG-SDH based connection control allows an ingress NG-SDH node to control the appropriate connection establishment process according to connection types such as Permanent Connection (PC), Soft Permanent Connection (SPC), Switched Connection (SC) over various SDH and Ethernet line cards.

• Journal of KIISE:Computing Practices and Letters
• /
• v.13 no.3
• /
• pp.141-152
• /
• 2007

In this paper, we present a network-oriented lightweight real-time system, which is composed of an event-driven operating system called the Embedded Lightweight Operating System (ELOS) and a generic multi hop ad hoc routing protocol suite. In the ELOS, a conditional preemptive FCFS scheduling method with a guaranteed time slot is designed for efficient real-time processing. For more elaborate configurations, we reinforce fault tolerance by supplementing semi-auto configuration using wireless agent nodes. The developed hardware platform is also introduced, which is a scalable prototype constructed using off-the-shelf components. In addition, in order to evaluate the performance of the proposed system, we developed a ubiquitous network test-bed on which several experiments with respect to various environments are conducted. The results show that the ELOS is considerably favorable for tiny ubiquitous networked systems with real-time constraints.

• Journal of the Korea Computer Industry Society
• /
• v.5 no.2
• /
• pp.227-233
• /
• 2004

Complex scheduling problems are related to planning, scheduling, constraint satisfaction problems, object-oriented concepts, and agent systems. Human preference-driven scheduling technique was to solve complex scheduling problems using constraint satisfaction problems and object-oriented concepts. We have tried to apply human preference-driven scheduling technique to reservation problems. For customer's satisfaction, we have considered customer's preferences in the reservation scheduling. The technique of reservation scheduling proposed in this thesis is based on object-oriented concepts. 1'o consider the over all satisfaction, the events of every object are alloted to the board along its priority. Constraints to reservation scheduling are classified to global and local. The definition of board and information of every event are global constraints and the preferences to object's board slots are local constraints. We have applied look-ahead technology to reservation scheduling in order to minimize backtracking not to fail the allotment of events.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.7
• /
• pp.543-552
• /
• 2013

For the safety messages in IEEE 802.11p/WAVE vehicles network environment, strict periodic beacon broadcasting requires status advertisement to assist the driver for safety. In crowded networks where beacon message are broadcasted at a high number of frequencies by many vehicles, which used for beacon sending, will be congested by the wireless medium due to the contention-window based IEEE 802.11p MAC. To resolve the congestion, we consider a MAC scheme based on slotted p-persistent CSMA as a simple non-cooperative Bayesian game which involves payoffs reflecting the attempt probability. Then, we derive Bayesian Nash Equilibrium (BNE) in a closed form. Using the BNE, we propose new congestion control algorithm to improve the performance of the beacon rate under saturation condition in IEEE 802.11p/WAVE vehicular networks. This algorithm explicitly computes packet delivery probability as a function of contention window (CW) size and number of vehicles. The proposed algorithm is validated against numerical simulation results to demonstrate its stability.

• Journal of Korea Multimedia Society
• /
• v.3 no.2
• /
• pp.101-111
• /
• 2000

Resource managing is very difficult because the multimedia data compressed by a VBR shows a bit rate change within high range, Therefore, the VOD server should use the prefetch method in order to improve system utilization, such as prefetching data in the overload period by a meta table that is the reference pattern of MPEG data which is analyzed off line. This prefetch method will not result in a failure to display at overload, however, this method can not keep a minimum loading time and low costs, because the prefetched section is being maximizes. In this paper, we suggest another method that the system utilization can be improved using the fixed prefetched section to keep loading time and costs under a constant range at overload. But this technique will result in a failure to display, due to fixed prefetched section. Rut, in this paper we suggest a drop module that drops only the B frame in the GOP, consistently distributes a lower drop in media quality for the user.