흰쥐에서 배측 봉선핵의 전기자극이 췌장의 외분비기능에 미치는 영향

서상원,박형진,Suh, Sang-Won,Park, Hyoung-Jin 대한생리학회 1990 대한생리학회지 Vol.24 No.2

The present investigation was performed to see a possible influence of the dorsal raphe nucleus (DRN) on pancreatic exocrine secretion in anesthetized rats since the DRN had been known to exert a regulatory mechanism on sympathetic activity which was known to be very important for pancreatic exocrine secretion, particularly in rats. Twenty-nine Sprague-Dawley rats fasted for 24 hours were anesthetized by i.p. injection of 1 g/kg of urethane. The pancreatic duct was cannulated to collect pancreatic juice while bile juice was diverted into the jejunum. The duodenopyloric junction was tightly ligated. After surgery for collection of pancreatic exocrine secretion and recording of carotid blood pressure, a coaxial electrode was stereotaxically inserted in the DRN with a guide of a brain atlas. And then, electrical stimulus of biphasic square wave with 2 v, 2 msec, 40 Hz was applied on the electrode for 10 minutes. Pancreatic volume flow and protein output secreted in 10 min were measured. Either bilateral cervical vagotomy or spinal cord transection at the level of $C4{\sim}C5$ was performed 20 min prior to stimulation of the DRN. 1) Electrical stimulation of the DRN resulted in significant (p<0.05) increase in pancreatic volume flow and protein output. These stimulatory effects were not affected by cervical vagotomy but completely abolished by cervical cord transection. 2) Electrical stimulation of the DRN also resulted in significant (p<0.05) rise of blood pressure of the carotid artery. The hypertensive effect was not affected by cervical vagotomy but completely abolished by cervical cord transection. The results strongly suggest that the DRN, a part of the central serotonergic system, could exert a stimulatory influence on pancreatic exocrine secretion by increasing the sympathetic activity in anesthetized rats.

Closed- form Physical Densities: An Extension to a Wider Class of Risk-Neutral Densities

서상원 ( Sang Won Suh ) 한국증권학회 2008 한국증권학회 발표논문집 Vol.2008 No.1

비선형 특징추출 기법에 의한 머리전달함수 ( HRTE ) 의 저차원 모델링 및 합성

서상원(Sang Won Suh),김기홍(Ki Hong Kim),김현석(Ki Hong Kim),김현빈(Hyun Suk Kim),이의택(Ee Taek Lee) 한국정보처리학회 2000 정보처리학회논문지 Vol.7 No.5

For the implementation of 3D Sound Localization system, the binaural filtering by HRTFs is generally employed. But the HRTF filter is of high order and its coefficients for all directions have to be stored, which imposes a rather large memory requirement. To cope with this, research works have centered on obtaining low dimensional HRTF representations without significant loss of information and synthesizing the original HRTF efficiently, by means of feature extraction methods for multivariate data including PCA. In these researches, conventional linear PCA was applied to the frequency domain HRTF data and using relatively small number of principal components the original HRTFs could be synthesized in approximation. In this paper we applied neural network based nonlinear PCA model (NLPCA) and the nonlinear PLS regression model (NLPLS) for this low dimensional HRTF modeling and analyze the results in comparison with the PCA. The NLPCA that performs projection of data onto the nonlinear surfaces showed the capability of more efficient HRTF feature extraction than linear PCA and the NLPLS regression model that incorporates the directional information in feature extraction yielded more stable results in synthesizing general HRTFs not included in the model training.

금융 시스템리스크를 감안한 금융기관 자기자본 규제정책

서상원 ( Sang Won Suh ) 한국금융학회 2010 금융연구 Vol.24 No.1

금융 감독정책은 금융 시스템 안정과 거시경제적 안정을 동시에 추구하면서 결정된다. 그런데 특히 경제불황기에는 두 목표간에 상충관계가 존재하기 때문에 감독정책 결정에서 당국의 세심한 주의가 필요하다. 본 연구의 목적은 정책당국의 감독정책 효과를 금융 시스템 및 거시경제적 안정측면에서 분석할 수 있는 모형을 제시하고 이를 통해 두 목표간 상충관계에 대한 구체적 정보를 제공함으로써 감독정책 결정에 도움을 주는데 있다. 주요 분석결과로는 (ⅰ) 심각한 경기불황기에 거시경제 안정을 위한 감독정책은 금융 시스템리스크를 높일 위험이 크며 (ⅱ) 은행들의 대출방식에 따라 감독정책의 효과가 달라질 수 있다는 점에 유의하여야 하고 (ⅲ) 경기불황기에 자기자본 적립의무를 경감시켜 은행대출을 증가시키려는 정책은 바젤Ⅰ에 비해 바젤Ⅱ에서 효과가 작게 나타나며 (ⅳ) 현재 경기불황이 심각한 상황에서 미래에도 경제상황이 개선되지 않으면 거시경제 안정을 위한 감독정책은 자칫 미래에 시스템리스크를 크게 상승시키는 부작용을 초래할 위험이 있다는 점 등을 들 수 있다. Financial systemic risk issues have become important since global financial crisis of 2008. Financial regulatory and supervisory policies had largely focused on how to maintain the soundness of individual financial institutions based on the belief that sound individual financial institutions guarantee against financial systemic risk. In particular, Basel Ⅱ changes bank capital regulation in such a way that bank credit risks are not severely affected by changes in borrowers` creditworthiness. However, the bank capital regulation in Basel Ⅱ does not take financial systemic risk into account but mainly concerns the soundness of individual banks. Moreover, Basel Ⅱ may induce procyclicality problem because loose bank capital regulation enables bank lending to grow further in boom periods while bank lending contracts due to tight bank capital regulation in recession periods. On the one hand, following Basel Ⅱ bank capital regulation, a financial regulator may be faced with procyclicality problem. On the other hand, if a regulator adjusts bank capital regulation so as to dampen business cycle fluctuations in recession periods, it may worsen the soundness of individual banks. This demonstrates the trade-off between macroeconomic stability and financial stability from a financial regulation policy perspective. This paper addresses financial regulator`s decision problem which should take both macroeconomic stability and financial stability into account. I present a model to analyze the effects of financial regulation policy on bank lending and financial systemic risk. This model can provide financial regulators with informations about the trade-off between macroeconomic stability and financial stability and therefore help them to form regulation policy. The model presented in this paper can analyze the trade-off between macroeconomic stability and financial stability and also is designed to incorporate many realistic assumptions. For example, the model assumes multiple banks, and each bank has heterogeneous borrowers with different creditworthiness. Credit ratings are assigned according to internal methods and change due to common or idiosyncratic shocks. The model is basically designed for a single period but extends for multi-periods without difficulty. Main findings are: (ⅰ) Regulation policies for enhancing macroeconomic stability might deteriorate financial stability in a severe recession period. (ⅱ) The effects of regulations may be dependent upon banks` lending behavior. (ⅲ) The effect of reducing capital requirement upon bank lending in a recession period is greater under Basel II than under Basel I. (ⅳ) In a dynamic analysis, regulation policies for enhancing macroeconomic stability might lead to deteriorated financial stability in the future, if current recession cannot rebound quickly.

연구발표 진행표 : A 발표장 : 정규화 기준값 산정에 관한연구

서상원(Sang Won Suh),이건모(Kun mo Lee),허영채(Young Chae Huh),하상선(Sang Sun Ha) 한국전과정평가학회 1999 한국전과정평가학회 정기총회 연구논문집 Vol.1999 No.0

P-chlorophenylalanine의 전처치가 산소중독시 발생되는 경련발작에 미치는 영향

서상원 ( Sang Won Suh ),김해준 ( Hae Joon Kim ) 국군의무사령부 1993 대한군진의학학술지 Vol.24 No.1

우리나라 은행부문의 시스템 리스크 측정

서상원 ( Sang Won Suh ) 한국금융연구원 2011 금융연구 Vol.25 No.2

Accurate measurement of systemic risk is required to efficiently implement financial regulation policies for financial stability. In this paper, we measure systemic risk of Korean banking sector by employing a new method proposed by Suh (2011) which extends existing methods based on option pricing approaches in order to effectively capture realistic features in banks` asset return dynamics and their correlations.12) Merton`s (1974) structural approach considers an equity as a European call option written on a firm`s asset value with the strike price of the matured debt amount. The method employed in this paper also regards an equity as a European call option, but the option is written on the net asset value (i.e., asset value minus debt amount) with the strike price of zero, departing from the usual structural approach. This deviation allows a realistic feature that banks` liabilities (as well as asset) continuously and randomly change because of their role of financial intermediation, while the usual structural approach assumes a fixed debt amount at maturity. The method models individual bank`s net asset value to depend on an observable common factor which is realistically featured with time-varying volatility. This feature enables not only individual bank`s net asset values but also their correlations to have time-varying volatility. Furthermore, it greatly facilitates estimation because the common factor is constructed as an observable variable and therefore allows bank-by-bank estimation. Systemic risk is measured with (i) the proportion of the number of default (or distressed) banks among all banks and (ii) the proportion of the debt amounts of default (or distressed) banks among all banks. We utilize the method to measure s ystemic risk of Korean banking sector from March 1999 to August 2010. The Korean banking sector is populated with ten to twelve banks during the sample period. We found that the Korean banking sector showed a sharp increase in the systemic risk during the recent global financial crisis period. Debt-weighted systemic risk level was lower than equal-weighted systemic risk level, which indicates that large banks are less susceptible to financial distress than small banks. The common factor prove its importance in measuring systemic risk. In particular, ignoring the common factor might lead to significant underestimation of the systemic risk.

바젤 2 도입과 은행의 대출행태 분석

서상원 ( Sang Won Suh ) 한국금융연구원 2006 금융연구 Vol.20 No.2

본 연구에서는 은행대출 결정에 관한 이론모형을 제시하였다. 특히 바젤 II 도입이 은행대출에 미치는 영향을 분석하기 위해 차주의 신용도 등이 모형에 포함되었으며, 또한 경제의 일부문에만 국한된 신용도 충격 발생에 따른 영향을 분석할 수 있도록 경제 내에 부문을 도입하였다. 주된 이론적 분석결과로는 첫째, 바젤 II 도입에 대한 QIS(Quantitative Impacts Study) 결과, 바젤II로 이행하면서 필요자기자본 규모가 증가하더라도 차주대체의 효과가 클 경우에 은행대출 규모가 반드시 감소하는 것은 아니다. 또한 바젤II로 이행하면서 어떤 부문에 대한 필요자기자본 규모가 감소하여도 해당 부문에 대한 은행대출 규모가 반드시 증가하는 것은 아니다. 둘째, 일부문에만 발생한 신용도 충격이 은행대출에 미치는 영향은 현행 BIS협약 하에서와 바젤II 하에서 서로 다르다. 셋째, 바젤II 하에서 은행대출의 경기순응성을 완화하기 위해 감독당국이 필요자기자본 적립비율을 변동시키는 정책을 사용할 경우 전 부문에 정책을 사용하는 것보다는 신용도 충격이 발생한 부문에 선택적으로 사용하는 것이 보다 효과적일 수 있다. This paper proposes a model of banks` lending behavior which incorporates obligor`s credit rating and introduces sectors in the economy to analyze the effects of Basel II on bank lending. Main analytical results are as follows: First, even if the minimum required capital is shown to increase from the Quantitative Impacts Study for the adoption of Basel II, it does not necessarily mean the decrease of bank lending. Moreover, even though the minimum required capital of a sector in the economy decreases while adopting Basel II, it does not necessarily imply the decrease of bank lending for the sector. Second, the effects of credit risk shocks in a sector on bank lending under the current Accord are qualitatively different with those under Basel II. Third, when regulators change the required capital ratio to mitigate the procyclicality of bank lending under Basel II, it would be more effective to implement it only into the sectors hit by credit risk shocks rather than into all sectors.

드럼세탁기의 감성품질 측정 시스템

서상원(Sang-won Suh),이창구(Changgoo Lee) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.7

도어락 스위치(Door-lock switch)는 드럼세탁기, 식기 세척기등 회전이나 열이 발생되어 작동 할 때 임의로 열지 못하도록 하는 가전제품에 쓰이는 도어안전잠금장치로 드럼세탁기에서는 없어서는 안 되는 중요한 부품 중의 하나이다. 드럼 세탁기 도어는 소비자가 사용 할 때 항상 느낌을 가지는 부분으로 안전성과 동시에 감성이 뒤따르는 부품이기도 하다. 본 논문은 드럼세탁기의 도어에 감성과 관련된 요소들을 조사하였으며, 도어락 스위치의 기구적인 구조들을 파악한 뒤 드럼세탁기에 장착 하였을 때 열림력, 닫힘력을 측정할 수 있는 지그와 소프트웨어를 제작하여 측정한 힘의 그래프를 분석하고 사용자에 의해 평가한 후, 드럼세탁기 도어락 스위치의 구조에 따른 감성에 차이점을 찾아보고 최적의 설계를 위한 요소를 제시하였다.

CNN 알고리즘을 이용한 체커스위치 불량 검출 시스템 개발

서상원(Sang-Won Suh),고요한(Yo-Han Ko),유성구(Sung-Goo Yoo),정길도(Kil-To Chong) 한국기계가공학회 2019 한국기계가공학회지 Vol.18 No.12

Various automation studies have been conducted to detect defective products based on product images. In the case of machine vision-based studies, size and color error are detected through a preprocessing process. A situation may arise in which the main features are removed during the preprocessing process, thereby decreasing the accuracy. In addition, complex systems are required to detect various kinds of defects. In this study, we designed and developed a system to detect errors by analyzing various conditions of defective products. We designed the deep learning algorithm to detect the defective features from the product images during the automation process using a convolution neural network (CNN) and verified the performance by applying the algorithm to the checker-switch failure detection system. It was confirmed that all seven error characteristics were detected accurately, and it is expected that it will show excellent performance when applied to automation systems for error detection.