한강수계에서의 부유사 예측을 위한 LOADEST 모형의 회귀식의 평가

박윤식,이지민,정영훈,신민환,박지형,황하선,류지철,박장호,김기성,Park, Youn Shik,Lee, Ji Min,Jung, Younghun,Shin, Min Hwan,Park, Ji Hyung,Hwang, Hasun,Ryu, Jichul,Park, Jangho,Kim, Ki-Sung 한국농공학회 2015 한국농공학회논문집 Vol.57 No.2

Typically, water quality sampling takes place intermittently since sample collection and following analysis requires substantial cost and efforts. Therefore regression models (or rating curves) are often used to interpolate water quality data. LOADEST has nine regression models to estimate water quality data, and one regression model needs to be selected automatically or manually. The nine regression models in LOADEST and auto-selection by LOADEST were evaluated in the study. Suspended solids data were collected from forty-nine stations from the Water Information System of the Ministry of Environment. Suspended solid data from each station was divided into two groups for calibration and validation. Nash-Stucliffe efficiency (NSE) and coefficient of determination ($R_2$) were used to evaluate estimated suspended solid loads. The regression models numbered 1 and 3 in LOADEST provided higher NSE and $R_2$, compared to the other regression models. The regression modes numbered 2, 5, 6, 8, and 9 in LOADEST provided low NSE. In addition, the regression model selected by LOADEST did not necessarily provide better suspended solid estimations than the other regression models did.

잡음환경에서 Teager 에너지의 전력 스펙트럼 편차에 기반한 음성 검출 알고리즘

박윤식,안홍섭,이상민,Park, Yun-Sik,An, Hong-Sub,Lee, Sang-Min 한국음향학회 2011 韓國音響學會誌 Vol.30 No.7

본 논문에서는 잡음환경에서 효과적인 음성을 검출하기 위한 새로운 음성검출 (VAD, voice activity detection) 알고리즘을 제안한다. 제안된 방법은 개선된 음성/비음성 검출을 위해 기존의 파워 스펙트럼 편차를 적용하는 대신 Teager 에너지 기반의 파워 스펙트럼 편차 (power spectral deviation)를 이용한다. 또한 향상된 VAD 성능을 위하여 각각의 주파수 밴드에 대한 음성부재확률 (speech absence probability)을 제안된 파워 스펙트럼 편차를 도출하는데 스무딩 (smoothing) 파라미터로 적용한다. 제안된 알고리즘은 기존의 방법과 객관적인 실험을 통해 비교 평가한 결과 다양한 배경잡음 환경에서 향상된 성능을 보였다. In this paper, we propose a novel voice activity detection (VAD) algorithm to effectively distinguish speech from nonspeech in various noisy environments. The presented VAD utilizes the power spectral deviation (PSD) based on Teager energy (TE) instead of the conventional PSD scheme to improve the performance of decision for speech segments. In addition, the speech absence probability (SAP) is derived in each frequency subband to modify the PSD for further VAD. Performances of the proposed VAD algorithm are evaluated by objective test under various environments and better results compared with the conventional methods are obtained.

시공간적 변화를 고려한 SATEEC 토양유실 평가시스템 개발

박윤식,김종건,장원석,임경재,Park, Yoon-Sik,Kim, Jong-Geon,Jang, Won-Seok,Im, Gyeung-Jae 한국수자원학회 2010 물과 미래(한국수자원학회지) Vol.43 No.7

SWAT과 SATEEC 모형을 이용한 토양유실량 비교

박윤식,김종건,허성구,김남원,안재훈,박준호,김기성,임경재,Park, Youn-Shik,Kim, Jong-Gun,Heo, Sung-Gu,Kim, Nam-Won,Ahn, Jae-Hun,Park, Joon-Ho,Kim, Ki-Sung,Lim, Kyung-Jae 한국농공학회 2008 한국농공학회논문집 Vol.50 No.1

Soil erosion is a natural process and has been occurring in most areas in the watershed. However, accelerated soil erosion rates have been causing numerous environmental impacts in recent years. To reduce soil erosion and sediment inflow into the water bodies, site-specific soil erosion best management practices(BMPs) need to be established and implemented. The most commonly used soil erosion model is the Universal Soil Loss Equation(USLE), which have been used in many countries over 30 years. The Sediment Assessment Tool for Effective Erosion Control(SATEEC) ArcView GIS system has been developed and enhanced to estimate the soil erosion and sediment yield trom the watershed using the USLE input data. In the last decade, the Soil and Water Assessment Tool(SWAT) model also has been widely used to estimate soil erosion and sediment yield at a watershed scale. The SATEEC system estimates the LS factor using the equation suggested by Moore and Burch, while the SWAT model estimates the LS factor based on the relationship between sub watershed average slope and slope length. Thus the SATEEC and SWAT estimated soil erosion values were compared in this study. The differences in LS factor estimation methods in the SATEEC and SWAT caused significant difference in estimated soil erosion. In this study, the difference was -51.9%(default threshold)${\sim}-54.5%$(min. threshold) between SATEEC and non-patched SWAT, and -7.8%(default threshold)${\sim}+3.8%$(min. threshold) between SATEEC and patched SWAT estimated soil erosion.

소아기관지(小兒氣管支) 천식(喘息)에 관(關)한 동서의학적(東西醫學的)인 고찰(考察)

박윤식,정규만,Park Yun-Sik,Jeong Gyu-Man 대한한방소아과학회 1987 대한한방소아과학회지 Vol.2 No.1

새로운 잡음전력 추정 기법을 적용한 음향학적 반향 및 배경잡음 제거 통합시스템

박윤식,장준혁,Park, Yun-Sik,Chang, Joon-Hyuk 한국음향학회 2009 韓國音響學會誌 Vol.28 No.7

본 논문에서는 주파수 영역에서 음향학적 반향 및 잡음 제거의 통합 시스템을 위한 효과적인 잡음전력 추정 기법을 제안한다. 제안된 방법은 잡음 제거 (NS, noise suppression)가 음향학적 반향 억제 (AES, acoustic echo suppression)의 후처리단으로 결합하여 사용되는 구조에서 발생하는 잡음전력 추정오차를 줄이기 위해 마이크로폰 입력신호의 음성부재확률 (SAP, speech absence probability)을 잡음전력 갱신을 위한 스무딩 (smoothing) 파라미터로 적용한다. 따라서 제안된 기법에서는 반향 억제 후 신호에서 잡음전력 갱신을 위한 SAP를 추출하는 대신 입력신호에 대한 SAP를 NS 알고리즘에 적용함으로서 잡음 제거기가 반향 억제 후 왜곡된 잡음 스펙트럼 구간에서는 잡음전력을 갱신하지 않도록 한다. 제안된 알고리즘은 기존의 방법과 객관적인 실험을 통해 비교 평가한 결과 다양한 배경잡음 환경에서 우수한 성능을 보였다. In this paper, we propose a efficient noise power estimation technique for an integrated acoustic echo and noise suppression system in a frequency domain. The proposed method uses speech absence probability (SAP) derived from the microphone input signal as the smoothing parameter updating noise power to reduce the noise power estimation error resulted from the distortions in the unified structure where the noise suppression (NS) operation is placed after the acoustic echo suppression (AES) algorithm. Therefore, in the proposed approach, the smoothing parameter based on SAP derived from the input signal instead of echo-suppressed signal should stop updating noise power estimates during the distorted noise spectrum periods. The performance of the proposed algorithm is evaluated by the objective test under various environments and yields better results compared with the conventional scheme.

청리자감탕이 Streptozotocin으로 유발(誘發)된 흰쥐의 당뇨병(糖尿病) 및 당뇨병합병증(糖尿病合倂症)에 미치는 영향

박윤식,윤경민,임은영,신현철,강석봉,Park, Yoon-Sik,Yoon, Gyeong-Min,Im, Eun-Yeong,Shin, Hyeon-Chul,Kang, Seok-Bong 대한한방내과학회 2010 大韓韓方內科學會誌 Vol.31 No.3

Objective : The object of this study was to observe the effects of aqueous extracts of Chunglijagam-tang(CLJGT), which has traditionally been used in Korean medicine for treating various diseases, on streptozotocin(STZ)-induced rat diabetes and related complications: diabetic nephropathy, hepatopathy and hyperlipemia. Methods : CLJGT extracts were orally administered once a day for 28 days at a dosage 50, 100 and 200mg/kg from 21 days after STZ treatment, and the changes on body weights, blood glucose levels, kidney and liver weights, serum BUN(blood urea nitrogen), creatinine, AST(aspartate transaminase), ALT(alanine aminotransferase), HDL(high-density lipoprotein), LDL (low-density lipoprotein), total cholesterol and triglyceride levels were observed with pancreatic malondialdehyde(MDA) and glutathione(GSH) contents. The results were compared with silymarin 100mg/kg. Results : Significant decrease of blood glucose levels, kidney and liver weights, serum BUN, creatinine, AST, ALT, LDL, total cholesterol, triglyceride levels, pancreatic malondialdehyde contents and significant increase of body weights, serum HDL levels, pancreatic glutathione contents were detected in CLJGT extracts 50, 100 and 200mg/kg administered groups as compared to the STZ control group. Conclusion : CLJGT extracts showed favorable effects on the STZ-induced diabetes and related complications mediated by their antioxidant effects as similar to silymarin. Therefore, it is expected that DBEH has potential for use in the management of diabetes and various diabetic complications.

음성 향상에서 강인한 새로운 선행 SNR 추정 기법에 관한 연구

박윤식,장준혁,Park, Yun-Sik,Chang, Joon-Hyuk 한국음향학회 2006 韓國音響學會誌 Vol.25 No.8

본 논문에서는 잡음 환경에서 단일 마이크로폰의 음성 향상에 대한 새로운 기법을 제시했다. 일반적으로 널리 알려진 스펙트럼 차감법에 근거한 음성 향상 기술은 신호 대 잡음비에 따른 스펙트럼 이득으로 표현된다. 대표적인 Ephraim과 Malah의 decision-directed (DD) 추정치는 잡음 구간에서 효율적으로 뮤지컬 잡음을 제거하지만 음성 구간에서는 이전 프레임의 음성 스펙트럼 성분에 더 큰 비중을 두기 때문에 a priori SNR의 프레임 지연이 발생한다. 따라서 DD에 의해 추정된 a priori SNR이 적용된 잡음 제거 이득은 현재 프레임보다 이전 프레임에 영향을 받으므로 음성 전이 구간에서 잡음 제거 성능을 저하시킨다. 본 논문은 DD의 가중치 파라미터에 Sigmoid Type의 함수를 적용하여 계산적으로는 간단하지만 효과적인 음성 향상 알고리즘을 제안한다. 제안된 접근 방식은 DD의 주요 파라미터인 a priori SNR 지연의 문제점을 해결하면서 뮤지컬 잡음 제거에 우수한 DD의 이점은 유지한다. 제안된 알고리즘의 성능은 다양한 잡음 환경에서 ITU-T P.862 Perceptual Evaluation of Speech Quality (PESQ) 와 Mean Opinion Score (MOS). 그리고 음성 스펙트로그램 (Spectrogram)에 의해 평가했고 기존의 DD의 고정된 가중치 파라미터를 사용했을 때 보다 향상된 결과를 나타내었다. This Paper presents a novel approach to single channel microphone speech enhancement in noisy environments. Widely used noise reduction techniques based on the spectral subtraction are generally expressed as a spectral gam depending on the signal-to-noise ratio (SNR). The well-known decision-directed(DD) estimator of Ephraim and Malah efficiently reduces musical noise under the background noise conditions, but generates the delay of the a prioiri SNR because the DD weights the speech spectrum component of the Previous frame in the speech signal. Therefore, the noise suppression gain which is affected by the delay of the a priori SNR, which is estimated by the DD matches the previous frame rather than the current one, so after noise suppression. this degrades the noise reduction performance during speech transient periods. We propose a computationally simple but effective speech enhancement technique based on the sigmoid type function for the weight Parameter of the DD. The proposed approach solves the delay problem about the main parameter, the a priori SNR of the DD while maintaining the benefits of the DD. Performances of the proposed enhancement algorithm are evaluated by ITU-T p.862 Perceptual Evaluation of Speech duality (PESQ). the Mean Opinion Score (MOS) and the speech spectrogram under various noise environments and yields better results compared with the fixed weight parameter of the DD.

강인한 음성향상을 위한 Minimum Statistics와 Soft Decision의 확률적 결합의 새로운 잡음전력 추정기법

박윤식,장준혁,Park, Yun-Sik,Chang, Joon-Hyuk 한국음향학회 2007 韓國音響學會誌 Vol.26 No.4

본 논문에서는 비정상적인 잡음 환경에서 음성향상을 위한 새로운 잡음 추정 기법을 제시한다. 제안된 방법은 잡음 전력 추정을 위해 주파수 채널별 음성부재확률 (SAP, Speech Absence Probability)을 선택적 가중 파라미터로 적용하여 음성 구간에서는 기존의 Minimum Statistics (MS)에 의한 잡음전력 추정치에 비중을 두고 비음성 구간에서는 Soft Decision (SD)에 기반한 잡음전력 추정치를 선택하도록 기존의 알고리즘을 결합한다. 제안된 알고리즘의 성능은 다양한 잡음 환경에서 음성향상기법에 적용하여 주관적인 음질평가 결과에 의해 평가하여 기존의 MS 또는 SD에 기반한 방법보다 향상된 결과를 나타내었다. This paper presents a new approach to noise estimation to improve speech enhancement in non-stationary noisy environments. The proposed method combines the two separate noise power estimates provided by the minimum statistics (MS) for speech presence and soft decision (SD) for speech absence in accordance with SAP (Speech Absence Probability) on a separate frequency bin. The performance of the proposed algorithm is evaluated by the subjective test under various noise environments and yields better results compared with the conventional MS or SD-based schemes.

음향학적 반향 제거를 위한 Soft Decision 기반의 동시통화 검출

박윤식,장준혁,Park, Yun-Sik,Chang, Joon-Hyuk 한국음향학회 2009 韓國音響學會誌 Vol.28 No.3

본 논문에서는 음향학적 반향 제거(AES, acoustic echo suppression)를 위해 주파수영역에서 soft decision 기법에 근거한 새로운 동시통화 검출 (DTD, double-talk detection) 알고리즘을 제안한다. 제시된 방법은 효과적인 DTD를 위해 상관계수 (cross-correlation coefficient)에 기반하여 hard decision을 사용하는 기존의 알고리즘 대신 주파수 영역에서 입력 및 원단신호의 VAD (voice activity detection) 결과와 음성 통계모델에 기반한 soft decision 방법을 도입하여 전역 근단화자존 재확률 (GNSPP, global near-end speech presence probability)을 DTD에 적용한다. 제안된 알고리즘은 기존의 방법과 객관적인 실험을 통해 비교 평가한 결과 다양한 배경잡음 환경에서 우수한 성능을 보였다. In this paper, we propose a novel double-talk detection (DTD) technique based on soft decision in the frequency domain. In the proposed method, global near-end speech presence probability (GNSPP) considering the statistical model assumption and voice activity detection (VAD) decision of the near-end and far-end signal are applied to the DTD algorithm in the frequency domain instead of the traditional hard decision scheme using cross-correlation coefficients. The performance of the proposed algorithm is evaluated by the objective test under various environments, and yields better results compared with the conventional scheme.