CS-ACELP 부호화기의 잡음특성 개선을 위한 에너지정합법

이행우 남서울대학교 공학연구센터 2002 공학연구 Vol.3 No.-

본 논문은 여러 배경잡음에서 높은 성능을 나타내는 8kbps CS-ACELP 부호화기의 음질개선방법에 관한 것이다. 파형정합방법을 이용하는 기존의 CELP 부호화기가 순수한 음성신호에 대해서는 우수한 음질을 제공하지만, 배경잡음에 대해서는 큰 음질저하를 가져온다. 따라서 본 논문에서는 음성신호뿐만 아니라 이러한 배경잡음에 대해서도 우수한 음질을 달성하는 에너지정합방법을 소개한다. 이 방법은 부가적인 비트를 요구하지 않으면서 효과적으로 음질을 개선한다. 실험 결과, 객관적 평가에서는 MSEGSNR이 0.01∼1.1dB 증가하였고, 주관적 평가에서는 MOS 점수가 평균 0.2, 최대 0.5점까지 증가하는 것으로 나타났다. 따라서 PPS 알고리즘을 적용한 부호화기의 음질이 최대 12%까지 향상되는 것으로 확인되었다. This paper describes a method for growing up the speech quality of 8kbps CS-ACELP speech coder under various background noises. While existing CELP coder using waveform matching method provides high quality for clean speech signals, it has significant quality loss for background noises. Therefore, this paper proposes the energy matching method with high quality for background noises as well as speech signals. This method effectively improves the speech quality without requiring any additive bits. As a result of experiments, in the objective estimation method, MSEGSNR were increased by 0.01∼1.1dB. Also, in the subjective estimation method, MOS was increased by 0.2 averagely and by 0.5 maximally. Therefore, it was proved that this algorithm achieves the improvement of speech quality by 12% maximally.

비상관 잡음을 이용한 음향반향제거기

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

This paper is on a new adaptive algorithm which can cancel the acoustic echo signals in the speaker-phone system. The proposed algorithm uses the normalized LMS algorithm with decorrelators. By doing so, it can be reduced the autocorrelation for the voice signals. As the results of simulations, it is proved that the echo canceller adopting this algorithm shows the improved ERLE of about more than 6 dB. Key Words : Speaker-phone, Echo cancellation, Decorrelation

철원 비무장지대 인근지역에서 두루미류의 월동생태 및 서식지 관리

이우신,임신재,허위행,최창용,최서윤,박용수,이창배 中央大學校 食糧資源硏究所 2003 食糧資源硏究所 論文集 Vol.15 No.1

This study was conducted to investigate wintering ecology and habitat using pattern of cranes for sound protection and management of the birds and their habitat near the Demilitarized Zone(DMZ) of Cheolwon, South Korea. Distribution of cranes seemed to be affected by road construction and human activity. Dried rice paddy was mainly habitat type of cranes in Cheolwon area. Gleaning was dominant behavior during day time. Ratio of alert was increased in afternoon. There was difference in time budget of behavior between red-crowned and white-naped cranes. For the stable wintering of cranes, minimum change of habitat, decrease of human disturbance and stable food maintenance would be needed in Cheolwon area.

인슐린의존형 당뇨병환자에서 임신중 병발한 당뇨병성 케톤산증 1예

이성근,신영구,이성규,정윤석,이관우,김현만,김행수 아주대학교 1997 아주의학 Vol.2 No.2

저자등은 인슐린의존형 당뇨병환자에서 임신중에 병발한 당뇨병성 케톤산증을 1예를 경험하였기에 문헌고찰과 함께 보고하는 바이다. IDDM is an autoimmune disease resulted from beta cell destruction and insulin deficiency, and developed mostly in children and puberty. Ketoaddosis remains one of the most senous complications that can occur in the pregnant diabetic. A 26-year-old woman, gravida 1, para 0, was admitted at 32 weeks gestation because of fever lasted for 6 days. She had been treated with insulin pump during the pregnancy. Blood sugar was well controlled before admission, and the etiology of her ketoacidosis was urinary tract infection and no insulin-intake. DKA was treated with fluids and intravenous insulin. Urinary tract infection was treated with antibiotics, based on culture test. Healthy newbom was later delivered by cesarean section due to fetal distress. We experienced a case of DKA in pregnant woman and report it with a review on literature.

Acoustic Echo and Noise Canceller Improvements for Hands-Free Telephones

이행우 남서울대학교 2005 남서울대학교 논문집 Vol.11 No.2

We propose a new strategy for echo cancellation, where we switch between the Least Mean Squares(LMS) and subband NLMS(SNLMS) algorithms, to achieve fast convergence and high steady-state echo return loss enhancement(ERLE).We start with a low order NLMS filter to achieve fast convergence. Later, we switch to a high order SNLMS filter to achieve high steady-state ERLE. In order to combat environmental noise, we propose cascading an adaptive noise canceling filter. The noise canceling filter converges in the mean to the optimal causal Wiener solution to filter the noise from the near-end signal. Finally, simulation results show the performance of the proposed echo and noise cancellation strategies.

UWB 통신을 위한 Rake 수신기 회로설계

이행우 남서울대학교 2005 남서울대학교 논문집 Vol.11 No.1

This paper proposes a hardware architecture for implementing the Rake receiver in the UWB wireless communication system. This architecture is the post-buffering Rake receiver functioning the Rake reception without requiring hardware complexities. Rake receiver using the adaptive filter is the architecture suitable to the environment with the little multi-path. If a UWB transceiver ASIC using this architecture is developed, advantages shall have the size of chip, the power dissipation.

인증서 검증서버의 인증경로 생성 메커니즘에 관한 연구

이행우,신광철 남서울대학교 2005 남서울대학교 논문집 Vol.11 No.2

PKI core basic architecture for securing informations have to minimize client's burden to generations of authentication paths. Also, It must be solved the lack of timing and managements in the CRL, inter-operations among PKI domains according to its environment. To remove problems in the existing PKI, the validation server solves problems of timing for validating authentications and CRL using OCSP, supports inter-operation of PKIs, arid manages the authentication strategy of inter-domain. This paper proposes fast and effective the generation method of authentication path in the validation server. Because it generates previously and saves the authentication path, it can give the authentication path fast on requiring a validation. With saving the used path, it provides effective the authentication path by reusing the saved path.

흡입관에 부착된 이젝터내의 유동특성에 관한연구

이행남,박길문,모양우,이덕구,설재림,김건일 朝鮮大學校 機械技術硏究所 2004 機械技術硏究 Vol.7 No.2

The ejector is used to get low pressure, and it has been applied to a lot of industry field like the heat engine, the fluid instrument power plant, the food industry, environment industry etc. because there are not any problem even it is mixed with kinds of liquid, gas, and solid. The flow characteristics in diffuser are investigated by PIV and CFD. The agreement between numerical analysis and experiment shows the validity of this study and the results of this study would be useful to the engineers who design for the flow systems for heating, ventilation, air conditioning and wastewater purification plants.

t-Butylhydroperoxide의 肝毒性에 대한 加味行滯湯 合 六味地黃湯의 效果

李樹行,金宇煥 동의대학교 한의학연구소 1997 동의한의연구 Vol.1 No.-

This study was carried out to determine whether Kamihaengche-tang plus Ydkmijihwang-tang(KCYH) exerts the protective effect against oxidant-induced liver cell injury. Cell injury was estimated by measuring lactate dehydrogenase (LDH) and alanine aminotransferase (ALT) release, and lipid peroxidation was estimated by measurimg malondialdehyde, a product of lipid peroxidation, in rabbit liver slices. tBHP increased the release of LDH and ALT enzymes in dose-dependent manner over the range of 0.2-2 mM concentrations. Similarly, tBHP also increased lipid peroxidation, indicating that tBHP-induced liver cell injury was attributed to lipid peroxidation. When 1% KCYH was added to incubation solution, the cell injury and lipid peroxidation induced by tBHP were markedly prevented. The protective effect of KCYH against the cell injury and lipid peroxidation induced by tBHP was dose-dependent in the range of 0.05-1% concentrations. These results indicate that KCYH exerts the protective effect against oxidant-induced liver cell injury, and this effect is attributed to prevention of lipid peroxidation, However, the precise mechanisms of antioxidant effect of KCYH remain to be defined.

LED 정보표시시스템의 휘도 균일성 개선

이행우 남서울대학교 2005 남서울대학교 논문집 Vol.11 No.2

The objective of this paper is to improve the uniformity of its brightness in the LED display system by the method arranging dynamically colors and revising the number. We propose the method to uniform its brightness which is low hardware complexities and fine picture quality. It was implemented by FPGA, and the test system was manufactured using the LED modules. The uniformity of its brightness in the LED display system is attained by placing effectively pulses for LED. In this research, We decided its system specifications, designed circuits of the functional blocks, developed the controller module, and manufactured the prototype display system.