음향반향신호의 제거를 위한 개선된 직교투사법

윤현민,Yun Hyun-min 한국정보통신학회 2005 한국정보통신학회논문지 Vol.9 No.4

본 논문에서는 음향반향 제거기에서 음성에 대하여 반향제거를 위한 진보된 새로운 기술인 개선된 직교투사법을 제안하였다. 이 결과를 NLMS(normalized least mean square) 적응 알고리즘과 비교하여 보면 개선된 직교투사법은 큰 자기상관을 갖는 신호에 대하여 음향제거 과정이 개선되는 것을 보여준다. 본 논문에서 제안한 개선된 직교투사법의 과정을 검증하기 위하여 프로그램을 작성하여 컴퓨터 모의실험을 실행하여 잡음과 음성에 대해 두개의 적응 알고리즘을 사용하여 수렴곡선을 관찰하였다. 이 두개의 입력신호의 모의실험 결과로부터 본 논문에서 제안한 방법을 음성과 잡음에 적용시킨 결과 빠른 수렴과 ERLE(echo return loss enhancement)가 높음을 보여주었다. This paper proposes the improved orthogonal projection method as a new technique advancing the performance of the echo cancellation for speeches in the acoustic echo canceller. Comparing with the used NLMS adaptive algorithm, it shows that this method improves the performance of the echo cancellation for signals with the large auto-correlation. In order to testify performances of the orthogonal projection method whom this paper proposes, we have coded a simulation program and executed computer simulations. We observed convergence curves by using two adaptive algorithm for noises and speeches. From simulation results for two input signals, the proposed method shows the high ERLE and the fast convergence and the stable operation in case of using speeches as well as noises.

등화기법을 적용한 OFDM 기반 DSRC 시스템

윤현민(Hyun-min Yun),강문규(Moon-Kyoo Kang) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.4D

차세대 시스템과 기존 DSRC 시스템의 채널환경 차이는 주파수 선택적 페이딩 채널환경이 되므로, 무선 다중경로 채널에서 심볼간 간섭이 발생하게 된다. 무선 다중경로 채널에서 데이터를 고속으로 전송할 경우, 신호는 페이딩, 심볼간 간섭에 의한 영향으로 높은 에러율을 갖게 된다. 그러므로 현재 개발된 DSRC 시스템의 변복조 방식은 1 Mbps이상의 데이터 서비스가 어렵다. 따라서 새로운 채널등화 기법 및 개선된 변복조 방식이 요구된다. OFDM 방식은 보호간격의 삽입을 통하여 심볼간 간섭을 방지할 수 있으므로 고속 데이터 전송에 적합하다. 그러나. 보호구간이 OFDM 방식에서의 각각의 심볼주기에 사용되는 채널 지연 확산보다 길어지므로 채널활용의 효율성에서 상당한 손실이 야기된다. 그러므로 등화기를 고속의 데이터 전송율과 긴 채널 지연확산 조건을 가지는 ITS 서비스에 적용하기 위해서는 심볼간 간섭을 제거할 필요가 있다. 본 논문에서는 OFDM-DSRC 시스템을 위한 채널 등화기를 설계하였으며, 다중경로 페이딩 환경에서 시뮬레이션을 통해 그 성능을 분석하였다. 그 결과, OFDM-DSRC 시스템을 위한 의사 LMMSE 등화기의 성능이 고속의 전송환경에서 LS 등화기보다 우수함을 알 수 있었다. The difference of the channel environment from former DSRC system and the next generation one comes from frequency selective fading channel environment, therefore ISI is occurred in wireless multi-path channel. The signal in wireless multi-path channel is affected by fading and ISI because of high data rate transmission, so the signal has the high error rate. The present modulation and demodulation method of DSRC system can not expect sufficient for providing data service over 1 Mbps, so the channel equalization and advanced modulation and demodulation methods are required. OFDM is generally known as an effective technique for high data rate transmission system, since it can prevent ISI by inserting a guard interval. However, a guard interval longer than channel delay spread has to be used in each OFDM symbol period, thus resulting a considerable loss in the efficiency of channel utilization. Therefore the equalizer is necessary to cancel ISI to accommodate advanced ITS service with higher bit rate and longer channel delay spread condition. In this thesis, the channel equalizer for the OFDM-DSRC system was designed and its performance in a multi-path fading environment was evaluated with simulation. As a result, the performance of Pseudo LMMSE equalizer for the OFDM-DSRC has been improved comparing with LS equalizer at higher bit rate transmission system.

암묵신호분리를 이용한 동시통화 음향반향제거기

이행우,윤현민,Lee, Haeng-Woo,Yun, Hyun-Min 한국정보통신학회 2012 한국정보통신학회논문지 Vol.16 No.2

본 논문은 암묵신호분리방법을 이용하여 동시통화를 가능하게 하는 음향반향제거기에 관한 것이다. 음향반향 제거기는 동시통화 구간에서 성능이 저하되거나 발산하게 된다. 그래서 근단화자신호를 추정해서 잔차신호로부터 차감하기 위하여 암묵신호분리방법을 사용한다. 암묵신호분리방법은 이중 마이크를 가지고 2차 통계적 성질을 이용한 반복적인 계산에 의해 근단화자신호를 추정해낸다. 그런데 폐쇄된 반향환경에서 암묵신호분리의 혼합모델은 다채널이기 때문에 분리계수를 직접 계산하지 않고 반향제거기의 계수를 복사하여 그대로 사용한다. 많은 시뮬레이션을 통하여 제안한 음향반향제거기의 성능을 검증하였다. 시뮬레이션 결과, 이 방법을 사용한 음향반향제거기는 동시통화의 유무에 상관없이 안전하게 동작하고, 일반적인 LMS 알고리즘에 비해 ERLE가 평균 20dB 향상되는 것으로 나타났다.

우수한 수렴특성을 갖는 3차원 열흐름 방정식의 이산화 방법

이은구,윤현민,김철성,Lee, Eun-Gu,Yun, Hyun-Min,Kim, Cheol-Seong 한국전기전자학회 2002 전기전자학회논문지 Vol.6 No.2

The simulator for the analysis of the lattice temperature under the steady-state condition is developed. The heat flow equation using the Slotboom variables is discretized and the integration method of the thermal conductivity without using the numerical analysis method is presented. The simulations are executed on the $N^+P$ junction diode and BJT to verify the proposed method. The average relative error of the lattice temperature of $N^+P$ diode compared with DAVINCI is 2% when 1.4[V] forward bias is applied and the average relative error of the lattice temperature of BJT compared with MEDICI is 3% when 5.0[V] is applied to the collector contact and 0.5[V] is applied to the base contact. BANDIS using the proposed method of integration of thermal conductivity needs 3.45 times of matrix solution to solve one bias step and DAVINCI needs 5.1 times of matrix solution MEDICI needs 4.3 times of matrix solution.

M/W 중계기용 유전체 공진 발진기 설계에 관한 연구

송윤원(Yun-Won Song),윤현민(Hyun-min Yun) 한국통신학회 2009 韓國通信學會論文誌 Vol.34 No.8D

본 논문에서는 마이크로파 중계 시스템을 위한 PLDRO (phase locked dielectric resonator oscillator)를 설계하고 제작하였다. 유전체 공진 발진기(Dieletric Resonator Oscillator, DRO)는 유전체 공진기의 등가회로 모델을 사용하여 유전체 공진기의 등가 파라미터를 구하고 이를 바탕으로 설계 및 제작하였다. 바렉터 다이오드와 유전체공진 발진기, 7.06㎓의 전압제어 유전체 공진 발진기(VCDRO)를 사용하여 제작하였으며, +10.88㏈m의 출력전력과 -95.87 ㏈c/㎐ @ 10㎑의 위상잡음이 측정되었다. In this paper, a phase locked dielectric resonator oscillator (PLDRO) has been designed and fabricated for microwave repeater system. A DRO has been designed and fabricated using calculated parameters of DR refered to it's equivalent circuit. Using the varactor diode and DRO, voltage controlled DRO of 7.06 ㎓ has been fabricated. An output power of +10.88 ㏈m and phase noise -95.87 ㏈c/Hz @ 10㎑ has been measured.

곤륜(BL60) 자침 후 발생한 족부의 봉와직염 및 족관절 윤활막염: 증례 보고

도현정 ( Hyun Jeong Do ),이은주 ( Eun Ju Lee ),박경훈 ( Gyung Hun Park ),박윤령 ( Yun Leong Park ),서종철 ( Jong Cheol Seo ),김철홍 ( Cheol Hong Kim ),윤현민 ( Hyun Min Yoon ) 경락경혈학회 2021 Korean Journal of Acupuncture Vol.38 No.4

The purpose of this study is to report a case diagnosed with cellulitis and ankle joint synovitis after acupuncture treatment. An 85-years old female suffering from low back pain was managed by acupuncture including BL60. After treatment, unintended ankle pain occurred. The pain was diagnosed with cellulitis and synovitis by MRI. The patient was transferred to the Western medical hospital, and ankle joint arthroscopic synovectomy was performed. It was difficult to find a clear relationship between acupuncture and ankle joint synovitis. But it would be reasonable to assume that cellulitis was associated with acupuncture needling and synovitis was followed. Serious adverse effects, such as septic arthritis, are rare, but need significant attention. For acupuncture treatment on the ankle, especially using BL60, the depth and manipulation should be carefully performed along with sterilization.

Z-Wave 시스템용 역 F형 안테나 설계

송윤원(Yun-Won Song),윤현민(Hyun-min Yun),이형기(Hyung-Ki Lee) 한국통신학회 2010 한국통신학회논문지 Vol.35 No.4D

인위적 CO₂ 누출에 따른 토양 CO₂ 플럭스와 농도의 시공간적 모니터링

김현준 ( Hyun-jun Kim ),한승현 ( Seung Hyun Han ),김성준 ( Seongjun Kim ),윤현민 ( Hyeon Min Yun ),전성천 ( Seong-chun Jun ),손요환 ( Yowhan Son ) 한국환경영향평가학회 2017 환경영향평가 Vol.26 No.2

CCS (Carbon Capture and Storage) is a technical process to capture CO₂ from industrial and energy-based sources, to transfer and sequestrate impressed CO₂ in geological formations, oceans, or mineral carbonates. However, potential CO₂ leakage exists and causes environmental problems. Thus, this study was conducted to analyze the spatial and temporal variations of CO₂ fluxes and concentrations after artificial CO₂ release. The Environmental Impact Evaluation Test Facility (EIT) was built in Eumseong, Korea in 2015. Approximately 34kg CO₂ /day/zone were injected at Zones 2, 3, and 4 among the total of 5 zones from October 26 to 30, 2015. CO₂ fluxes were measured every 30 minutes at the surface at 0m, 1.5m, 2.5m, and 10m from the CO₂ releasing well using LI-8100A until November 13, 2015, and CO₂ concentrations were measured once a day at 15cm, 30cm, and 60cm depths at every 0m, 1.5m, 2.5m, 5m, and 10m from the well using GA5000 until November 28, 2015. CO₂ flux at 0m from the well started increasing on the fifth day after CO₂ release started, and continued to increase until November 13 even though the artificial CO₂ release stopped. CO₂ fluxes measured at 2.5m, 5.0m, and 10m from the well were not significantly different with each other. On the other hand, soil CO₂ concentration was shown as 38.4% at 60cm depth at 0m from the well in Zone 3 on the next day after CO₂ release started. Soil CO₂ was horizontally spreaded over time, and detected up to 5m away from the well in all zones until CO₂ release stopped. Also, soil CO₂ concentrations at 30cm and 60cm depths at 0m from the well were measured similarly as 50.6±25.4% and 55.3±25.6%, respectively, followed by 30cm depth (31.3±17.2%) which was significantly lower than those measured at the other depths on the final day of CO₂ release period. Soil CO₂concentrations at all depths in all zones were gradually decreased for about 1 month after CO₂ release stopped, but still higher than those of the first day after CO₂ release stared. In conclusion, the closer the distance from the well and the deeper the depth, the higher CO₂ fluxes and concentrations occurred. Also, long-term monitoring should be required because the leaked CO₂ gas can remains in the soil for a long time even if the leakage stopped.

수치해석을 이용한 전력 BJT의 정특성 분석

이은구,윤현민,김철성,Lee, Eun-Gu,Yun, Hyun-Min,Kim, Cheol-Seong 한국전기전자학회 2002 전기전자학회논문지 Vol.6 No.2

An algorithm for analyzing the characteristics of the power BJT using numerical analysis method is proposed. The Fermi-Dirac statistics is used to calculate the carrier concentration in highly doped region. Philips Unified mobility model, SRH model and Auger model is used to calculate the recombination current of base region. To verify the accuracy of the proposed method, the collector current of BANDIS is compared with the measured data in the condition of the base current increased from $1.0[{\mu}A]\;to\;3.5[{\mu}A]$. The collector current of BANDIS show a maximum relative error within 8.9% compared with the measured data.

실외 인위적 온난화 및 강수 조절이 소나무 묘목의 생리적 특성과 생장에 미치는 영향

박민지(Park, Min Ji),윤순진(Yun, Soon Jin),윤현민(Yun, Hyeon Min),장한나(Chang, Hanna),한승현(Han, Seung Hyun),안지애(An, Jiae),손요환(Son, Yowhan) 한국기후변화학회 2016 한국기후변화학회지 Vol.7 No.1

Climate change affects plant responses on physiological characteristics and growth, and Pinus densiflora, one of the major tree species in Korea, are expected to be particularly vulnerable to rising temperature and increased precipitation. This study was conducted to investigate the effects of an open-field warming and precipitation manipulation on physiological characteristics and growth of P. densiflora seedlings. Seedlings of 2-year-old P. densiflora were planted in April, 2013, in open-field nursery located at Korea University. The air temperature of warmed plots had been set to be 3℃ higher than the control plots using infrared lamps. Precipitation was manipulated to be 30% lower or higher than the control, using transparent panels and drip irrigation. Net photosynthetic rate, total chlorophyll content, seedling height, root collar diameter and biomass were measured from April, 2014 to April, 2015. The increase in new shoot biomass from warming was statistically significant, with the biomass in warmed plots about 2-fold higher than in the control plots in 2014 and 2015. This result might be related to advanced bud burst and increased occurrence of abnormal new shoots in warmed plots. Meanwhile, the results of net photosynthetic rate, total chlorophyll content, seedling height, root collar diameter and total biomass from warming and precipitation manipulation were not statistically significant, but tendencies of lower net photosynthetic rate and higher seedling height and biomass in warmed plots compared to the control were shown. Such might be speculated as results of the extended growth period. When root to shoot (R/S) ratio was calculated from the biomass data obtained in April 2014 and April 2015, increased R/S ratio was observed regardless of the treatments applied. Drought tolerance of P. densiflora and particularly low annual precipitation observed in 2014 were suggested as the possible reasons.