• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.525-530
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• 2008

There are a few core technologies to enable high-performance $4^{th}$ generation (4G) broadband wireless communication system. A multiple input multiple output (MIMO) provides high-rate transmission through expended channels by multiple array antennas in both sender and receiver side. Also orthogonal frequency division multiplexing (OFDM) is well-known as the most appropriate technique for high data rate transmission such as Mobile WiMAX and WLAN. Efficient decrease of inter-carrier interference (ISI) and inter-carrier interference (ICI) are the reasons for why OFDM is suitable for high-performance transmission, 4G mobile communication. In this paper, we mainly focus on two of objects, combination between MIMO and OFDM, and OFDM channel simulator using Ray-tracing algorithm. The results of this paper can be used implementation of a Wireless Software Platform for 4G Mobile Communication Systems.

• 반도체디스플레이기술학회지
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• 제9권2호
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• pp.11-14
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• 2010

In this paper, an improved binary-CDMA (Code Division Multiple Access) system for high speed multimedia data transmission will be presented. The improved binary CDMA technology will be used in municipal wireless network. The new name of the system is the Guardian system using a binary CDMA technology. The Guardian system can provide high data rate, and improve its throughput by minimizing latency from the limitation of resources of system bus during multimedia data transmission. Finally, we analyze the performance of Guardian modem according to the report of wireless data transmission test.

• 전자공학회논문지A
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• 제33A권7호
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• pp.15-22
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• 1996

In the soliton transmission system for a long-length and high bit rate data transmission systme using the nonlinear/dispersive optical fibers, the improtant problem is the loss characteristics and is the limited transmission rate by interaction forces. In this paper, It is explained the reasons of moved time position for the soliton peak value due to interaction force sof adjacent solitons. And for the analysis of interaction force affection level in the losslessmedia, we define the percent parameter of error rate due to the interaction forces and propose the optimum time distance of adjacent solitons by peak value tracking methods. With the results, initial percent of error is approximately 50% when itme difference between adjacent solitons is 5 times of funddametnal soliton pulse width. And it is confirmed that maximum transmission length of th esolitons is approximately 38 times of fundamental soliton period, which the maximum allowable percoent of error is 50%.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.113-116
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• 2000

Phase noise of oscillator gives the performance degradation significantly when a high carrier frequency and low transmission rate are used. The BER(Bit Error Rates) degradation of QPSK(Quadrature Phase Shift Keying) transmission is analyzed with the oscillator phase noise level specified in downstream physical interface of LMDS(Local Multipoint Distribution Services) which is described in DAVIC(Digital Audio Visual Council). The model used for the phase noise is a power-law model. We also investigated the effects of the various transmission rates on system performance. For the transmission rate below 0.5 Mbps, the BER performance is severely degraded and we verified that the transmission rate, 20 Mbps, is adequate for the downstream of LMDS systems.

• International Journal of Advanced Culture Technology
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• 제6권4호
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• pp.266-274
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• 2018

Securing field screens through LTE broadcasting is a very valuable technology in news production because of its locality and concurrency. TV has the advantage of being able to deliver news faster than newspapers and make live coverage on the scene of events and events. To maximize this, not only middle-end broadcasters but also existing broadcasting stations are taking an active role in broadcasting using LTE. However LTE broadcasting has yet to secure any conflicting values of broadcasting stability and securing high-definition. The key to solving this difficulty is the transmission rate of Bit Rate. This paper compares the Bit Rate transmission method, which is variable and fixed, to provide more on-site screens through LTE, and presents the Bit Rate adjustment method as a method of screen stabilization through experiment. Consequently, the most stable broadcast screen can be obtained when transmitting and connecting it to broadcasting in a variable 5M method.

• 한국통신학회논문지
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• 제31권3B호
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• pp.232-238
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• 2006

본 논문에서는 셀룰러 시스템에서 다양한 특성을 갖는 밀티미디어 서비스에 우선순위를 각각 부여하여 효율적으로 제어하여 핸드오버 서비스나 신규 서비스에 대한 블록킹 확률을 최소화하는 호 수락제어 기법을 제안하였다. 본 알고리즘은 비실시간 서비스들이 대역폭을 공유하는 Packing 방식, Queuing 방식, Power reallocation 방식의 호 수락 제어 방법에 관한 것으로 비실시간 서비스들의 트래픽 특성에 따라 공유 대역폭을 할당하고 남은 잉여 자원을 우선순위가 높은 실시간 서비스에게 제공하여 QoS를 보장하였다. 본 논문에서 성능판단 파라메타로는 블록킹 확률과 강제절단 확률을 설정하였고 다양한 형태의 멀티미디어 트래픽에 대해서 블록킹 확률과 강제절단 확률을 시뮬레이션을 통하여 각각 비교 분석하였다.

• 한국의학물리학회지:의학물리
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• 제33권4호
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• pp.108-113
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• 2022

Purpose: Proton therapy has been used for optimal cancer treatment by adapting its Bragg-peak characteristics. Recently, a tissue-sparing effect was introduced in ultrahigh-dose-rate (FLASH) radiation; the high-energy transmission proton beam is considered in proton FLASH therapy. In measuring high-energy/ultrahigh-dose-rate proton beam, Faraday Cup is considered as a dose-rate-independent measurement device, which has been widely studied. In this paper, the feasibility of the simply designed Faraday Cup (Poor Man's Faraday Cup, PMFC) for transmission proton FLASH therapy is investigated. Methods: In general, Faraday cups were used in the measurement of charged particles. The simply designed Faraday Cup and Advanced Markus ion chamber were used for high-energy proton beam measurement in this study. Results: The PMFC shows an acceptable performance, including accuracy in general dosimetric tests. The PMFC has a linear response to the dose and dose rate. The proton fluence was decreased with the increase of depth until the depth was near the proton beam range. Regarding secondary particles backscatter from PMFC, the effect was negligible. Conclusions: In this study, we performed an experiment to investigate the feasibility of PMFC for measuring high-energy proton beams. The PMFC can be used as a beam stopper and secondary monitoring system for transmission proton beam FLASH therapy.

• 한국통신학회논문지
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• 제31권9B호
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• pp.785-791
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• 2006

HCCA에서 채널 예약 정보를 가진 CF-Poll 프레임을 QoS-Data 프레임에 피기백하여 채널 효율성을 향상시키도록 하였다. 그러나 망 내의 하나의 QSTA라도 물리계층 전송속도가 감소할 경우 CF-Poll 프레임을 피기백한 QoS-Data 프레임은 가장 낮은 물리계층 전송속도를 가진 QSTA에 맞추어 전송해야 한다. 따라서 물리계층 전송 속도가 낮을 때 CF-Poll을 피기백하는 것은 지연을 증가시킬 뿐만 아니라 전체 망 성능을 감소시킬 수 있다. 본 논문에서는 이러한 현상을 QSTA의 채널전송속도 저하에 의한 피기백 문제라고 정의하였으며, 이러한 문제에 의한 성능 감소를 평가하였다. 시뮬레이션 결과로 CF-Poll을 피기백했을 때 임의의 QSTA의 물리계층 전송속도가 낮으면 지연이 최대 25% 증가하였다. 반면 물리계층 전송속도가 높을 경우 지연이 최대 7.8% 감소하는 것을 알 수 있었다. 또한 지연의 측면에서 서비스 트래픽 부하에 따라 전체 QSTA의 최저물리계층 전송속도가 24에서 36Mbps 이상일 때 CF-Poll 피기백의 이득이 발생하는 것을 발견하였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제4권4호
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• pp.275-279
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• 2004

A new burst mode clock and data recovery circuit is realized that improves the previousldy-known gated-oscilletor technique with half rate clock recovery, The circuit was fabricated with 0.25um CMOS technology, and its functions were confirmed up to 1 Gbps.

• Current Optics and Photonics
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• 제1권4호
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• pp.289-294
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• 2017

A high-performance time-division multiplexing (TDM) -based multiuser (MU) multiple-input multipleoutput (MIMO) system for efficient indoor visible-light communication (VLC) is presented. In this work, a MIMO technique based on RGB light-emitting diodes (LEDs) with selection combining (SC) is utilized for data transmission. That is, the proposed scheme employs RGB LEDs for parallel transmission of user data and transmits MU data in predefined slots of a time frame with a simple and efficient design, to schedule the transmission times for multiple users. Simulation results demonstrate that the proposed scheme offers an approximately 6 dB gain in signal-to-noise ratio (SNR) at a bit error rate (BER) of $3{\times}10^{-5}$, as compared to conventional MU single-input single-output (SISO) systems. Moreover, a data rate of 66.7 Mbps/user at a BER of $10^{-3}$ is achieved for 10 users in indoor VLC environments.