무선 접속 기술의 최신 동향

나유찬,오승철,오성택 남서울대학교 공학연구센터 1999 공학연구 Vol.1 No.-

It is possible to transmit a large amount of sound, video, and data over wired networks based upon the growing Information Superhighway. However, the existing available access networks are composed of much lower speed two-pair networks that can not handle multimedia information. To solve this problem, wireless access techniques yielding mobility and portability must be more efficient than increasing the capacity of wired networks. Also the WLL system is emerging as a highly attractive solution for the local loop network in many countries. It is one of the important means of providing telephone services more cheaply and quickly than through a wireline. Therefore in this paper, we introduce WLL. and the LMCS technology, (and service trends recently new local loop technique) which are now spotlighted in wireless access technology fields.

영상처리를 위한 적응적 알파 - 절사평균 필터에 관한 연구

나유찬 남서울대학교출판국 2011 남서울대학교 정보통신 논문집 Vol.8 No.1

Video segmentation is an essential part in region-based video coding and any other fields of the video processing. Among lots of methods proposed so far, the watershed method in which the region growing is performed for the gradient image can produce well-partitioned regions globally without any influence on local noise and extracts accurate boundaries. But, it generates a great number of small regions, which we call over segmentation problem. Therefore we proposes that adaptive α-trimmed mean filter for resolving the over segmentation of image.

정보통신기술의 발달이 화물유통량에 미치는 효과에 관한 연구

나유찬 남서울대학교 2005 남서울대학교 논문집 Vol.11 No.2

As logistics activities of Seoul Metropolitan area expands to include even Southern Kyounki and Northern Chungnam Province, the understanding of cargo flow become increasingly important. previous research in traffic flow measured cargo flow only from the perspective of the national level, not specific region such as Metropolitan area. This trend resulted in logistics decisions that help to facilitate national level planning but do not always provide necessary information for regional level. Therefore, the purpose of this paper is to present an analysis of traffic flow of Seoul-Kyungki Metropolitan area in the IT logistics era.

격자도움형 방향성 결합기 광 필터 특성에 관한 연구

나유찬 남서울대학교 2005 남서울대학교 논문집 Vol.11 No.2

In this study, we proposed polarization characteristics of the GACC filter obtained using the TE and TM mode coupler which has a different grating periods and duty ratio. We found that GACC has It's inherent limit on SSR due to its abrupt onset of the grating perturbation. With suitable tapering of the coupling strength by varying the grating duty ratio, we expected that SSR could be drastically improved. As a result, the theoretical side-lobe suppression ratios (SSRs) for single and double stage uriform type GACC optical filters are approximately -9dB and -18dB, respectively.

이동통신에서의 다중로 전파특성에 관한 연구

라유찬 남서울대학교 1998 남서울대학교 논문집 Vol.4 No.-

Multipath propagation measuring system based on PN code correlation detection method has been built to study the next generation mobile radio communication and wave propagation characteristics of IMT-2000 bandwidth. Cihwa plant superintendent area has been selected for basic and accurate measurement and study. The experiments are carried out with respect to the RMS delay spread and the mean excess delay in the two kind of geographical areas, LOS (Line of Sight) and N-LOS (Non Line of Sight). The measurement results obtained in Ciwha plant superintendent propagation environment are 0.023㎲ - 0.22㎲ of RMS delay spread for LOS area, and 0.068㎲-0.37㎲ of RMS delay spread for LOS area.

Mobitex용 9.6kbps모뎀 개발에 관한 연구

나유찬 남서울대학교 2005 남서울대학교 논문집 Vol.11 No.2

This thesis aims at the study of 9.6kbps modem development for wireless data communication(Mobitex network), which are designed for two way massage services by using the network of wireless packet. This modem has the features of GMSK demodulation by using Gaussian filter, which has the co-amplitude in a better condition and narrowness bandwidth and high performance in BER, compared with existing MSK modulation. In case of BT=0.3, we designed this receiver to reduce RF output power spectrum at received data of symbol demodulation and avoid inter-symbol interference(ISI) so that we can apply this modem to wireless data communication which are currently in service for wireless modem in china.

무선 LAN과 블루투스 주파수간에 간섭 영향 분석

라유찬,오승철,오성택 남서울대학교 공학연구센터 2001 공학연구 Vol.2 No.-

The Wireless LAN and Bluetooth use the same frequency Bandwidth 2.4GHz and it leads to cause interference between the systems and, on the basis of IEEE 802.11, we made a test and analysis on the influence derived there from. We got the test result by setting the test condition of 30mW for the wireless LAN Tx power and 100mW for Bluetooth Tx power. When there is no wireless LAN, regardless of distance between Master and Slave, Throughput was stable enough with 0.57Mbps, and when Bluetooth Slave approached to the Wireless LAN, before 25 feet, Throughput was sharply decreased from 0.3Mbps and, after 25 feet, it was so seriously influenced that it cannot be used again. And, when it is located far from of 30 feet, regardless of distance, Throughput was around 0.5Mbps and was slightly influenced compared with when there is no Wireless LAN, but is wasn't serious.

WLL 무선가입자 접속장치 송신단의 전력 증폭기 설계

라유찬 남서울대학교 2002 남서울대학교 논문집 Vol.8 No.-

In this thesis, We will state the production and design of WLL system power amplifier in transmit terminal. The producing resource is domestic amplifier of which the transmit frequency is between 2.30GHz and 2.33GHz and the power is 1W class. In design, We used Advanced Design System of HP company to predict all kinds of results of the signal. The Microstrip circuit was produced on dielectric plate by etching method. After that, We compared with the results of simulation. The gain of carrier input was linear but in case of W-CDMA wave, spurious radiation above 42dBc/30㎑ was transmitted when the input was above 10dBm.

WDM시스템에서 OOK 와 FSK 전송을 위한 수신기 특성 연구

나유찬 남서울대학교 2005 남서울대학교 논문집 Vol.11 No.2

We analysis of the receiver which received OOK and the FSK transmission signal that were a general digital transmission technique in a WDM system. We expressed various error probability with the m which was bandwidth and a bit numerical function and carried out performance evaluation of a receiver in a performance evaluation way. When error probability was 10^(-4) which is m = 10, as for the receive sensitivity of OOK, the 1.7×10^(2) , FSK got 2.2×10^(2) through simulation. And the receive sensitivity of OOK and FSK was able to get each 2.15×10^(2) and 3.07×10^(2) when it was error probability of 10^(-9) which is m = 25. Transmission of 23Gb/S showed that it was possible when we does the 10^(-9) that was basis error probability of a light communication system with a basis through this, and a coding profit was with 10^(8) and transmission capacity of 75Gb/s confirmed that it was possible if a code rate was with 0.8.

Adaptive trimmed mean 필터를 이용한 영상의 과분할 방지에 관한 연구

나유찬,송창영,박형근 남서울대학교 2003 남서울대학교 논문집 Vol.9 No.-

Video segmentation is an essential part in region-based video coding and any other fields of the video processing. Among lots of methods proposed so far, the watershed method in which the region growing is performed for the gradient image can produce well-partitioned regions globally witflout any influence on local noise and extracts accurate bowndanes. But, it generates a great number of small regions, which we call over segmentation problem. Therefore we proposes that adaptive trimmed mean filter for resolving the over segmentation of image.