• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.152-152
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• 2019

This study demonstrates a novel approach of remotely sensed estimates of stream flow at fifteen hydrological station in the Han River Basin, Korea. Multi-temporal data of the European Space Agency's Sentinel-1 SAR satellite from 19 January, 2015 to 25 August, 2018 is used to develop and validate the flow estimation model for each station. The flow estimation model is based on a power law relationship established between the remotely sensed surface area of water at a selected reach of the stream and the observed discharge. The satellite images were pre-processed for thermal noise, radiometric, speckle and terrain correction. The difference in SAR image brightness caused by the differences in SAR satellite look angle and atmospheric condition are corrected using the histogram matching technique. Selective area filtering is applied to identify the extent of the selected stream reach where the change in water surface area is highly sensitive to the change in stream discharge. Following this, an iterative procedure called the Optimum Threshold Classification Algorithm (OTC) is applied to the multi-temporal selective areas to extract a series of water surface areas. It is observed that the extracted water surface area and the stream discharge are related by the power law equation. A strong correlation coefficient ranging from 0.68 to 0.98 (mean=0.89) was observed for thirteen hydrological stations, while at two stations the relationship was highly affected by the hydraulic structures such as dam. It is further identified that the availability of remotely sensed data for a range of discharge conditions and the geometric properties of the selected stream reach such as the stream width and side slope influence the accuracy of the flow estimation model.

• 한국추진공학회지
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• 제22권3호
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• pp.14-20
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• 2018

초고속 엔진을 제어하는데 필요한 엔진으로 유입되는 공기유량의 추정기법에 대해 제안하였다. 비행 중 획득 가능한 정보를 활용하기 위하여 공기유량 계산식을 비행 중 측정 가능한 변수로 변경하였고, 추정 정확도에 대한 각각 변수의 기여도를 평가하였다. 제안한 추정식은 간단한 형태로 변형하였고, 측정 불확도를 분석하였다. 아울러 센서의 오차에 따른 민감도 분석을 통하여 공기유량 추정 기법 선택을 위한 참고자료를 제시하였다.

• 전자공학회논문지B
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• 제32B권3호
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• pp.48-56
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• 1995

This paper presents a method of implementing efficient optical flow estimation for dynamic scene analysis using the hierarchical Hopfield neural networks. Given the two consequent inages, Zhou and Chellappa suggested the Hopfield neural network for computing the optical flow. The major problem of this algorithm is that Zhou and Chellappa's network accompanies self-feedback term, which forces them to check the energy change every iteration and only to accept the case where the lower the energy level is guaranteed. This is not only undesirable but also inefficient in implementing the Hopfield network. The another problem is that this model cannot allow the exact computation of optical flow in the case that the disparities of the moving objects are large. This paper improves the Zhou and Chellapa's problems by modifying the structure of the network to satisfy the convergence condition of the Hopfield model and suggesting the hierarchical algorithm, which enables the computation of the optical flow using the hierarchical structure even in the presence of large disparities.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.14-19
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• 2005

Instream flow is necessary to manage the basic function of the rivers. The evaluation method of instream flow in a big river has been studied widely, However, the study in a small river hasn't researched. In theses days the environmental function of a river becomes very important. The evaluation method and secure of instream flow are basic conditions to perform it. Especially view of stream, recreation, protection of ecology are highly demanded in a urban according to the multipurpose of river spaces. Methods for determining the instream flow in the stream were explored and examined through careful reviews and evaluations of available literatures. Development of the instream flow estimation method is based on the reviewed results and methods which can be used within the acceptable levels.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.29-35
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• 1996

For the Reactor Coolant System(RCS) flow rate measurement by the secondary calorimetric heat balance method, the coolant temperature of the hot leg is needed. Several Resistance Temperature Detectors(RTD) are installed in the hot leg to measure the temperature, but the average value of RTDs does not correctly represent the energy-averaged(bulk) temperature because of the thermal stratification phenomenon. Therefore some correction is introduced to predict the bulk temperature, but the correction inevitably contains uncertainty because the stratification is not defined well quantitatively yet. Therefore a large uncertainty for the correction has been used for the conservative estimation. But unrealistically large uncertainty causes degradation of the measurement method and yields difficulty to meet the acceptance criterion in start-up flow measurement test. In this paper, an analytical estimation is made on the correction and the related uncertainty using the measured hot leg velocity profile of System 80 reactor flow model test and the measured temperatures of YGN 3&4 and PVNGS 1&2 start-up tests. The results reveal that the magnitude of the correction uncertainty is much smaller than that used in the previous design. Therefore, the confidence on the flow rate measurement method can be improved and the difficulty in start-up flow measurement test can be lessened if the smaller correction uncertainty obtained through this estimation is applied.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.56-59
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• 1997

Vision system is mainly consist of three parts of perception, action. One of these parts, perception system detects visual target in surrounding environment. Block-based motion estimation with compensation is one of the popular approaches without accuracy. The hierarchical method the optical flow with gradient is used to improve optical flow time delay.

• 유공압시스템학회논문집
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• 제4권4호
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• pp.1-7
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• 2007

Flow rate is one of the important variables for precise motion control and detection of the faults and fluid loss in many hydraulic components and systems. But in many cases, it is not easy to measure it directly. The orifice area of a servo valve by which the fluid flows is one of key factors to monitor the flow rate. In this paper, we have constructed an estimation algorithm for the effective orifice area by using the model of a servo valve cylinder control system and Kalman filter algorithm. Without geometry information about the servo valve, it is shown that the effective orifice area can be estimated by using only displacement and pressure data corrupted with noise. And the effect of the biased sensor data and system parameter errors on the estimation results are discussed. The paper reveals that sensor calibration is important in accurate estimation and plausible parameter data such as oil bulk modulus and actuator volume are acceptable for the estimation without any error. The estimation algorithm can be used as an useful tool for detecting leakage, monitoring malfunction and/or degradation of the system performance.

• 전기학회논문지
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• 제61권8호
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• pp.1083-1090
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• 2012

In this paper, we present the section load estimation program of distribution system for smart distribution management system. The proposed program is composed with three parts. One is the consistency check part for switch measurements which consist a section. The consistency check is divided into the current and angle test. For the current test, we examine the input and output power flow for the switch group. For the angle test, the result of power flow calculation at previous step is used. Another is the voltage estimation part for the measured switches. We use the weighted least square (WLS) method for the voltage estimation. The third is the part of final section load calculation. The database structure for accomplishing the developed estimation program is also proposed. To verify the accuracy of the experimental results, case studies are performed using a actual data of Jeju island. The developed program can be effectively applied to the distribution operation systems.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2006년도 학술대회 1부
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• pp.780-785
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• 2006

HCI, 비전 기반 사용자 인터페이스 또는 제스쳐 인식과 같은 많은 분야에서 3 차원 얼굴 모션을 추정하는 것은 중요한 작업이다. 연속된 2 차원 이미지로부터 3 차원 모션을 추정하기 위한 방법으로는 크게 외형 기반 방법이나 모델을 이용하는 방법이 있다. 본 연구에서는 동영상으로부터 3 차원 실린더 모델과 Optical flow를 이용하여 실시간으로 얼굴 모션을 추정하는 방법을 제안하고자 한다. 초기 프레임으로부터 얼굴의 피부색과 템플릿 매칭을 이용하여 얼굴 영역을 검출하고 검출된 얼굴 영역에 3 차원 실린더 모델을 투영하게 된다. 연속된 프레임으로 부터 Lucas-Kanade 의 Optical flow 를 이용하여 얼굴 모션을 추정한다. 정확한 얼굴 모션 추정을 하기 위해 IRLS 방법을 이용하여 각 픽셀에 대한 가중치를 설정하게 된다. 또한, 동적 템플릿을 이용해 오랫동안 정확한 얼굴 모션 추정하는 방법을 제안한다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.105-110
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• 1999

Unused irrigation water due to delievery losses and management losses. and ground water releases from infiltration in the paddy irrigation system are eventually returned to the stream. They are called as irrigation return flow. It affects the discharge of drought flow in the down strenamflow. And it may contain chemicals, and threaten streamflow quality . Thus, the accurage estimation of irrigation return flow is important to the streamflow modeling and water resources planning , and also to the control of agriculutral nonpoint source pollution . The irrigation return flow of pumped water was investigated in the Keum river watershed.