초음속 노즐에서 발생하는 응축충격파 진동의 피동제어

백승철,권순범,김희동,Baek, Seung-Cheol,Kwon, Soon-Bum,Kim, Heuy-Dong 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.7

Rapid expansion of a moist air or a stream through a supersonic nozzle often leads to non-equilibrium condensation shock wave, causing a considerable energy loss in flow field. Depending on amount of latent heat released due to non-equilibrium condensation, the flow is highly unstable or a periodical oscillation accompanying the condensation shock wave in the nozzle. The unsteadiness of the condensation shock wave is always associated with several kinds of instabilities as well as noise and vibration of flow devices. In the current study, a passive control technique using a porous wall with a plenum cavity underneath is applied for the purpose of alleviation of the condensation shock oscillations in a transonic nozzle. A droplet growth equation is coupled with two-dimensional Navier-Stokes equation system. Computations are carried out using a third-order MUSCL type TVD finite-difference scheme with a second-order fractional time step. An experiment using an indraft wind tunnel is made to validate the present computational results. The results show that the oscillations of the condensation shock wave are completely suppressed by the current passive control method.

Bleed Slot을 사용한 응축충격파의 피동제어

백승철,권순범,김희동,Baek, Seung-Cheol,Kwon, Soon-Bum,Kim, Heuy-Dong 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.7

The current study describes experimental and computational works on the passive control of the steady and unsteady condensation shock waves, which are generated in a transonic nozzle. The bleed slots are installed on the contoured wall of the transonic nozzle in order 10 control the magnitude of the condensation shock wave and its oscillations. For computations, a droplet growth equation is copuled with two-dimensional Navier-Stokes equation systems. Computations are carried out using a third-order MUSCL type TVD finite-difference scheme with a second-order fractional time step. Baldwin-Lomax turbulence model is employed to close the governing equations. An experiment using an indrafi transonic wind tunnel is made to validate the computational results. The current computations represented well the experimental flows. From both the experimental and computational results it is found that the magnitude of the condensation shock wave in the bleed slotted nozzle is signi ficantly reduced, compared with no passive control of solid wall. The oscillations of the condensation shock wave are successfully suppressed by a bleed slot system.

출판저널 칼럼

백승철,Baek, Seung-Cheol 대한출판문화협회 1989 출판저널 Vol.37 No.-

다중해상도 특성에 기반 한 정규화를 이용한 영상 분류

백승철(Seung-Chul Baek),홍준식(Jun-Sik Hong) 한국정보기술학회 2011 한국정보기술학회논문지 Vol.9 No.10

Candida mogii ATCC 18364를 이용한 D - Xylose로부터 Xylitol 생산

백승철(Seoung-Chul Baek),권윤중(Yun-Joong Kwon) 한국생물공학회 2004 KSBB Journal Vol.19 No.3

地籍學의 硏究方法에 관한 硏究

백승철(Baek Seung-Cheol),이범관(Lee Beom-Gwan) 한국지적학회 2003 한국지적학회지 Vol.19 No.2

본 연구의 목적은 사회과학의 연구방법에 대한 실태를 조사·분석하고, 이를 토대로 지적학의 연구방법을 제시하는데 있다. 이상의 연구목적을 효율적으로 달성하기 위해 연구범위를 사회과학분야의 연구방법으로 한정하고, 문헌조사법을 통해 사회과학분야의 연구방법에 대한 실태를 조사하고, 분석방법으로는 비교분석법을 사용하여 사회과학분야의 연구방법에 대한 실태를 분석하며, 이를 토대로 지적학의 인구방법을 제시하였다. 분석 결과 지적학 연구를 위한 접근방법으로는 법률적 접근방법, 행정적 접근방법, 기술적 접근방법, 경제적 접근방법, 역사적 접근방법, 생태학적 접근방법으로 제시할 수 있었고, 조사방법으로는 문헌조사법, 사례조사법, 설문조사법, 인터넷조사법으로 제시할 수 있었으며, 분석방법으로는 비교분석법, 기술적 분석법, 통계적 분석법으로 제시되었다. The purpose of this study is to survey and analyze the research methods for social science and thereupon, suggest research methods for cadastral science. For this purpose, the scope of this study was limited to the research methods for social science, and thereby, relevant literature was reviewed to understand the research methodology for social science. For the analysis method was used the comparative analysis method to analyze the conditions of the research methods for social science, and thereupon, suggest research methods for cadastral science. The resultant research methods for cadastral science are legal, administrative, technical, economic, historical and ecological approaches, while survey methods for the science are literature review, case study, questionnaire survey. Lastly, the methods of analysis for cadastral science are comparative analysis, descriptive analysis and statistical analysis.

The Development of Local Markets and the Establishment of a New Circulation System in Late Chosǒn Society

백승철 ( Baek Seung-ch'ŏl ) 서울대학교 규장각한국학연구원 1999 Seoul journal of Korean studies Vol.12 No.-

건설VE에 대하여

백승철(Seung Cheol Baek) 대한토목학회 2020 대한토목학회지 Vol.68 No.2

독립성분 분석기법과 다중해상도 특성에 기반 한 영상 분류

백승철(Seung-Chu Baek),홍준식(Jun-Sik Hong) 한국정보기술학회 2012 Proceedings of KIIT Conference Vol.2012 No.11

본 논문에서는 다중해상도에서 암묵신호원분리(Blind Source Seperation, BSS)분야에서 발전된 독립성분분석(Independent Component Analysis, 이하 ICA)기법과 GBD 알고리즘을 이용한 영상 분류 방법을 제안한다. 모의실험 결과로부터 GBD 알고리즘에 의한 영상 분류에서는 k가 1일 때 영상 분류가 되지 않았지만, ICA기법에 의한 영상 분류는 k에 상관없이 영상분류가 진행되었다. 또한 GBD 알고리즘에 비하여 k가 감소할 때 그 편차가 적어 좋은 영상 분류 특성을 나타내었다. 실험에 사용된 영상들은 명암도의 차이에 상관없이 LSE 값을 기준으로 순차적으로 정렬이 가능하였다. 통신 분야에서 송·수신을 하기 위한 데이터양의 선택에 있어 최적의 영상 정보의 전 처리로서 필요한 만큼의 영상 정보의 압축에 응용될 수 있을 것으로 기대된다. In this paper, we present an image classification method using ICA(independent component analysis) which has advanced in the BSS(Blind source separation) field in a multi-resolution and GBD algorithm. Our simulation results show that image classification with the GBD algorithm did not perform well when k is 1, whereas image classification with the ICA techniques did perform well independent of the value of k. In addition, as the value of k gets smaller, the ICA technique achieves a better characteristics of image classification due to little deviation compared to the GBD algorithm. The images used in these experiments can be sorted by the LSE values while independent of differences in their brightness. In order to choose the amount of data to be transmitted and/or received, our proposed algorithm will be used to compress the image data as a preprocessor for obtaining an optimal image information.

스트레스 관련 피부질환 환자의 혈장내 β - endorphin의 변화

백승철 ( Seung Churl Baek ),김정원 ( Chung Won Kim ) 대한피부과학회 1995 대한피부과학회지 Vol.33 No.5

Background : Stress has long been known to play a role in many dermatologic disorders ard can affect the onset and course of the disorder in some patients. Stress-induced exacerbation or onset of symptoms has been reported in chronic urticaria, alopecia areata, berpes simplex, herps zoster, and psoriasis vulgris, and these diseases can be classified as stress-associated dermatoses. Beta p-endorphin is one if the most important mediators of stress, which is known to be generat ed upon stimulation of t.he pituitary adrenal axis, and its secretion increases during periods of stress. Objective : In order t,o see wheather p-endorphin might be related to the onset or recurrence of stress-associated dermatses, we compared the plasma concentration of p-endorphin in patients with stress associated dematoses with those of healthy subjects. Methods : The concentation of p-endorphin in sera was quantified by radioimmunoassay, usirg the INCSTAR 'IRIA Kit for plasma p-endorphin. Each patient was asked to indicate if they be lieved that their skin proilem began after an important stressful event in their lives. Results : There was no significant difference in plasma p-endorphin levels between patient,s with chronic urticaria, alopeciareata, herpes simplex, and herpes zoster and healthy subjects(p>0.05), whereas in patients witi psoriasis vulgaris, plasma level of p-endorphin was significantly in creased(p<0.001). There was no relationship between the stressful events and plasma pendorphin concentrations. Conclusions : The plasma p-endorphin level is not correlated with the onset or recurrence of stress-associated dermatuses such as chronic urticaria, alopecia areata, herpes simplex, and herp.s zoster. The increase in p-endorphin in psoriasis vulgaris is more likely that this peptide is generted by the lymphocyte irliltrate in the skin and/or by lymphocytes when they recirculate rath:.r than by the activation of the pituitary-adrenal axis by stress. (Kor J Dermatol 1995;33(5): 841-846)