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정압기의 임계유동 특성과 배관망해석 모델링에 관한 연구 (I) - 압력비 영향 -
신창훈,하종만,이철구,허재영,임지현,주원구,Shin Chang Hoon,Ha Jong Man,Lee Cheol Gu,Her Jae Young,Im Ji Hyun,Joo Won Gu 대한기계학회 2005 大韓機械學會論文集B Vol.29 No.12
Since the interior shape of a pressure regulator is complex and the change of fluid resistance at each operation condition is rapid and big, the pressure regulator can become the major factor that causes big loss in pipelines. So the suitable pressure regulator modeling by each operation condition is important to obtain reliable results especially in small scale pipeline network analysis. And in order to prevent the condensation and freezing problems, it is needed to confirm both whether temperature recovery is achieved after passing by the pressure regulator's narrow neck and how much amount of low temperature area that can cause condensate accumulation is distributed by various PCV models at every inlet-outlet pressure ratio. In this research, the numerical model resembling P company pressure regulator that is used widely for high pressure range in commercial, is adopted as the base model of CFD analysis to investigate pressure regulator's flow characteristics at each pressure ratio. Additionally it is also introduced to examine pressure regulator's critical flow characteristics and possibility of condensation or freezing at each pressure ratio. Furthermore, the comparison between the results of CFD analysis and the results of analytic solution obtained by compressible fluid-dynamics theory is attempted to validate the results of CFD modeling in this study and to estimate the accuracy of theoretical approach at each pressure ratio too.
신창훈,김형진,홍종락,양승민,Shin, Chang-Hoon,Kim, Hyung-Jin,Hong, Jong-Rak,Yang, Seung-Min 대한구강악안면외과학회 2007 대한구강악안면외과학회지 Vol.33 No.5
Purpose: The purpose of this study was to determine the incidence of antral septa and the accuracy of panoramic radiograph in identifying maxillary sinus septa. In addition, when panoramic radiograph led to a false diagnosis of more than majority, we analyzed findings of the panoramic radiograph. Patients and methods: This study included 180 patients who were radiographically examined before the surgery was done using both panoramic and computerized tomographic radiographs(CT scan), Samsung Medical Center from April 2003 to March 2006, and examined the incidence of antral septa, the false diagnosis rate of panoramic radiograph, and radiographic characters in case of false diagnosis. Only those bone lamellae were considered as septa that showed a height of at least 3.0mm. It was thus possible to exclude the alveolar recess. One oral and maxillofacial surgeon(OMFS) determined the presence or absence of sinus septa in CT scan, and five OMFS determined the presence or absence of sinus septa in panoramic radiograph. Results: The septa were observed in 81 of 360 sinuses(22.5%). All septa were oriented in a buccopalatal plane. More or less greater prevalence was observed in the second molar region(38.2%) but no predominant location was found. Panoramic radiograph led to false diagnosed septa in 361 of 1800 cases(20.1%). In case of false diagnosis of more than majority, superimposed image on zygomatic process was 44.1%, faint image in the region not related to sinus lifting 26.5%, faint image in the region related to sinus lifting 17.6%, and misconception for superimposed image 11.8% Conclusion: In this study we could get clinico-anatomical information of septum in the maxillary sinus. Compared to CT scan, panoramic radiograph can not clearly differentiate the sinus septa, but we consider that panoramic radiograph may improve its usefulness if we take additional modified panoramic radiograph and clinical exam.
다중 비디오카메라에서 색 정보를 이용한 특정 이동물체 추적 알고리듬
신창훈,이주신,Shin, Chang-Hoon,Lee, Joo-Shin 한국정보처리학회 2004 정보처리학회논문지B Vol.11 No.3
In this paper, the interesting moving objects tracking algorithm using color information on Multi-Video camera is proposed Moving objects are detected by using difference image method and integral projection method to background image and objects image only with hue area, after converting RGB color coordination of image which is input from multi-video camera into HSI color coordination. Hue information of the detected moving area are normalized by 24 steps from 0$^{\circ}$ to 360$^{\circ}$ It is used for the feature parameters of the moving objects that three normalization levels with the highest distribution and distance among three normalization levels after obtaining a hue distribution chart of the normalized moving objects. Moving objects identity among four cameras is distinguished with distribution of three normalization levels and distance among three normalization levels, and then the moving objects are tracked and surveilled. To examine propriety of the proposed method, four cameras are set up indoor difference places, humans are targeted for moving objects. As surveillance results of the interesting human, hue distribution chart variation of the detected Interesting human at each camera in under 10%, and it is confirmed that the interesting human is tracked and surveilled by using feature parameters at four cameras, automatically. 본 논문은 다중 비디오카메라에서 색 정보를 이용한 특정 이동물체 추적 이동물체 추적 알고리듬을 제안한다. 제안된 방법은 다중 비디오카메라로부터 입력되는 영상의 RGB 칼라 좌표계를 HSI 칼라 좌표계로 변환한 후, 영상의 색조 영역만을 가지고 배경영상과 물체가 존재하는 영상에서 차영상 기법과 가산투영 기법을 사용하여 이동물체를 검출한다. 검출된 이동물체 영역의 색조는 0도부터 360도 사이에서 24단계로 정규화 된다. 정규화된 이동물체의 색조 분포도를 구한 후, 가장 높은 분포를 갖는 3개의 정규화 레벨과 3개의 정규화 레벨 사이의 간격을 이동물체의 특징파라미터로 사용하였다. 각 카메라간의 이동물체 동일성 관별은 이동물체 특징파라미터를 가지고 판별하고, 추적 감시하였다. 제안된 방법의 타당성을 검토하기 위하여 실내에 각기 다른 장소에 4대의 카메라를 각각 설치하여 이동물체의 대상을 사람으로 놓고, 특정사람을 감시한 결과 각 카메라에서 검출된 특정사람의 색조분포도 변화는 10%내를 유지함을 보였고, 특징 파라미터로 4대의 카메라에서 특정사람이 자동 추적감시 됨을 확인하였다.
신창훈(Chang-Hoon Shin),강정식(Jeong-Sick Kang),박수남(Soo-Nam Park),이지훈(Ji-Hoon Lee) 한국항해항만학회 2007 한국항해항만학회 학술대회논문집 Vol.2 No.추계
컨테이너항만의 물동량 예측은 항만의 계발 및 운영계획을 위해 매우 중요한 과정이다. 일반적으로 회귀분석, ARIMA등의 통계적 방법론을 통해 많은 예측이 이뤄져왔다. 최근의 연구에서는 인공 신경망(ANN)기법을 통한 예측이 이뤄지고 있으며 기존의 선형적인 기법을 대신하고 있다. 본 연구에서는 선형모델과 비선형모델에 강점이 있는 ARIMA와 신경망 모델을 결합해 보다 효과적인 예측 모델을 개발하고자 한다. 실제 항만의 과거 자료를 통해 모델의 적합성을 측정하였고 항만의 특성에 따라 모형의 적합성이 다양하게 나타났다. The forecast of a container traffic has been very important for port plan and development. Generally, statistic methods, such as regression analysis, ARIMA, have been much used for traffic forecasting. Recent research activities in forecasting, with artificial neural networks(ANNs) suggest that ANNs can be a promising alternative to the traditional linear methods. In this paper, a hybrid methodology that combines both ARIMA and ANN models is proposed to take advantage of the unique strength of ARIMA and ANN models in linear and nonlinear modelling. The results with port traffic data indicate that effectiveness can differ according to the characteristics of port.