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김동한,정태학 대한상하수도학회 2003 상하수도학회지 Vol.17 No.6
As a sequencing batch reactor process is operated in the time orientation, it has flexibility of operation, which could easily accomodate aerobic, anoxic, and anaerobic conditions for biological nutrient removal in a reactor through the simple control of aeration. The aeration process of the sequencing batch reactor has been controlled on the basis of dissolved oxygen dynamics. Dissolved oxygen dynamics well represents the characteristics of reactions in a reactor. The first plateau of dissolved oxygen after aeration is related to the balance of oxygen, which is supplied by aeration and utilized by nitrification. The second rapid increase of dissolved oxygen is closely related to the end of nitrification. By applying the control strategy based on dissolved oxygen dynamics, aeration time for the optimal aerobic period is adjusted in a sequencing batch reactor. Aeration time is mainly correlated with the concentration of nitrogen in the influent and could also provide the characteristics of nitrification. The anoxic period could be prolonged through aeration control, so endogenous denitrification is maximized. The removal of phosphorus is enhanced simultaneously.
상태공간모형을 이용한 연속회분식반응조의 상태 및 매개변수 추정
김동한,정태학 대한상하수도학회 2003 상하수도학회지 Vol.17 No.6
The model for a biological nutrient removal process has become essential for the design and operation. The statespace model based on the extended Kalman filter for a sequencing batch reactor process has been developed to reflect uncertainties and dynamics in a real process. It is feasible to estimate states included in the process model, which are not easily measured, by using the extended Kalman filter through the prediction and correction. It is also possible to simultaneously estimate states and parameters reflecting the characteristics of the process at various conditions. It is necessary to choose the suitable covariance matrix and to adopt parameters from observability in the estimation of states and parameters. In a sequencing batch reactor process observability may exist while the reactions related to measurements are proceeding. States and parameters converge rapidly to the real values while observability exists.
KOMPSAT-5 SLC 영상과 AIS 데이터에 기반한 선박탐지
김동한,이윤경,김상완,Kim, Donghan,Lee, Yoon-Kyung,Kim, Sang-Wan 대한원격탐사학회 2020 大韓遠隔探査學會誌 Vol.36 No.2
국가해양영토에서 불법어업활동을 하는 어선으로부터 해상자원과 영토를 보호하기 위해 지속적인 모니터링과 즉각적인 대응은 필수적인 요소이다. Synthetic Aperture Radar (SAR) 영상은 넓은 촬영 범위를 가지고 있으며, 기상과 주야 조건에 영향을 받지 않아 광역적인 해상 모니터링에 효과적이다. 그러나 SAR 영상의 데이터 크기와 스펙클 노이즈 등 다양한 특성으로 인해 처리속도와 탐지율이 높은 선박탐지 알고리즘 개발은 쉽지 않다. 본 논문에서는 국내 최초의 X-band SAR 위성인 KOMPSAT-5에 적합한 선박탐지 알고리즘을 개발 적용하였다. 효율적인 선박탐지를 위해 선박탐지 알고리즘은 Human Visual Attention System (HVAS), SAR-Split, Constant False Alarm Rate (CFAR) 알고리즘의 특성을 융합하여 적용했다. 또한, SAR 영상의 관측모드 별 특성을 고려한 SAR-Split 알고리즘 적용을 통해 탐지율을 향상시켰다. SAR 영상으로부터 탐지된 선박은 Automatic Identification System (AIS) 데이터와의 매칭을 통해 탐지율 분석이 수행되었다. 탐지된 선박은 AIS 자료와 전반적으로 잘 매칭되었으며, SAR 영상의 모드 별 특성을 고려하여 적용했을 때 보다 향상된 탐지율을 보였다. 탐지율은 Enhanced Standard (ES) 모드에서 약 80%, Standard (ST) 모드에서 약 64%의 결과를 보였다. 선박 탐지결과에서 발생한 대부분의 오탐지는 선박의 이동으로 발생하는 기포항적, AIS의 위치오차 등으로 발생하였다. 개발된 선박탐지 알고리즘은 대한민국 국가해양영토 광역 감시망 구축에 기여할 것으로 기대된다. Continuous monitoring and immediate response is essential to protect the national maritime territory and maritime resources from the activities of illegal ships. Synthetic Aperture Radar (SAR) images with a wide range of images are effective for maritime surveillance asthe weather and day-night conditions rarely affect to image acquisition. However, an effective ship detection is not easy due to the huge data size of SAR images and various characteristics such as the speckle noise. In this study, the Human Visual Attention System (HVAS) algorithm was applied to KOMPSAT-5 to extract the initial targets, and the SAR-Split algorithm depending on the imaging modes was used to remove false alarms. The detected targets were finally selected by the Constant False Alarm Rate (CFAR) algorithm and matched with the ship's Automatic Identification System (AIS) information. Overall, the detected targets were well matched with AIS data, but some false alarms by ship wakes were observed. The detection rate was about 80% in ES mode and about 64% in ST mode. It is expected that the developed ship detection algorithm will contribute to the construction of a wide area maritime surveillance network.
연속회분식반응조에서 호흡률에 기반한 포기공정의 예측제어
김동한 대한상하수도학회 2019 상하수도학회지 Vol.33 No.6
As aeration is an energy-intensive process, its control has become more important to save energy and to meet strict effluent limits. In this study, predictive aeration control based on the respirometric method has been applied to the sequencing batch reactor (SBR) process. The variation of the respiration rate by nitrification was great and obvious, so it could be a very useful parameter for the predictive aeration control. The maximum respiration rate due to nitrification was about 60 mg O2/L‧h and the maximum specific nitrification rate was about 7.5 mg N/g MLVSS‧h. The aeration time of the following cycle of the SBR was daily adjusted in proportion to that which was previously determined based on the sudden decrease of respiration rate at the end of nitrification in the respirometer. The aeration time required for nitrification could be effectively predicted and it was closely related to influent nitrogen loadings. By the predictive aeration control the aerobic period of the SBR has been optimized, and energy saving and enhanced nitrogen removal could be obtained.