• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.8 no.2
• /
• pp.299-306
• /
• 1996

This work presents an analytical model, so called modified LMTD method, to predict the thermal performance of finned-tube heat exchanger under frosting conditions. In this model, the total heat transfer coefficient and effective thermal conductivity of the frost layer were defined as a function of frost surface temperature. The surface temperature of the frost layer formed on the heat exchanger was calculated through the analysis of the heat and mass transfer process in the air and frost layer. To examine the validity of this analytical model, the computed results from the present model, such as heat transfer rate, frost mass and thickness of frost, were compared with the ones of the expermental work and LMED method.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.32B no.7
• /
• pp.974-988
• /
• 1995

In this paper, we propose a range image segmentation algorithm using robust regression. We derive a least $\kappa$th-order square (LKS) method by generalizing the least median of squares (LMedS) method and compare it with the conventional robust regressions. The LKS is robuster against outliers than the LMedS and shows performance similar to the residual consensus (RESC). The RESC uses the predetermined number of sorted residuals, whereas the LKS uses an adaptive parameter determined by given observations rather than the a priori knowledge. Computer simulation with synthetic and real range images shows that the proposed LKS algorithm gives better performance than the conventional ones.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.7 no.1
• /
• pp.161-170
• /
• 1995

This study is concerned with the numerical analysis of performance on fin-tube heat exchanger under frosting condition. In this work, tube-by-tube method using LMED is employed. The present results are compared with O'Neal's experimental and numerical results. A standard evaporator model with 2rows-2columns is selected to investigate the effects of the various parameters such as fin pitch, air flow velocity, and humidity. The results show that frost thickness and the amount of frost per unit area decrease as fin-pitch becomes narrower. In the meantime, frost thickness and accumulation rate increase with higher inlet air humidity. It is shown that heat transfer rate increases during 30minutes and then it decreases. Heat transfer rate and the amount of frost increase with air velocity, however frost thickness does not increase over a certain velocity.

• Proceedings of the Korean Information Science Society Conference
• /
• 1998.10c
• /
• pp.446-448
• /
• 1998

본 논문은 두 장의 스테레오 영상으로부터 자동적으로 특징점 정합을 수행하도록 하는 한 방법을 제안한다. Correlation기반의 특징점 정합을 빠르고 안정적으로 수행하며 이 때에 발생하는 애매성 문제에 대한 해결방법을 제시한다. 또한, LMedS방법을 사용하여 outlier를 효과적으로 제거시키고 에피폴라 기하를 이용하여 정합의 성능을 향상시킨다. 실내, 실외 영상에 대한 다양한 실험결과는 본 논문에서 제안하는 방법이 빠르고 효율적임을 보여준다.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.40 no.5
• /
• pp.357-364
• /
• 2003

The main difficulty in estimating the fundamental matrix stems from the unavoidable outliers inherent in the given correspondence matches. Several researches showed that the estimation results are much dependent on selecting the corresponding points. These represent that it is important to solve the problems due to errors on the point locations and mismatches. In this paper, our analysis shows that if the evenly distributed corresponding points are selected, we can estimate a more precise fundamental matrix. This paper presents novel approaches to estimate the fundamental matrix by considering the inlier distributions. In order to select evenly distributed points, we divide the entire image into the subregions, and then examine the number of the inliers in each subregion and the area of each region. The simulation results showed that our consideration of the inlier distribution can provide a more precise estimation of the fundamental matrix.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.40 no.5
• /
• pp.347-356
• /
• 2003

Camera pose and scene geometry estimation from video sequences is widely used in various areas such as image composition. Structure and motion recovery based on the auto calibration algorithm can insert synthetic 3D objects in real but un modeled scenes and create their views from the camera positions. However, most previous methods require bundle adjustment or non linear minimization process [or more precise results. This paper presents a new auto' calibration algorithm for video sequence based on two steps: the one is key frame selection, and the other removes the key frame with inaccurate camera matrix based on an absolute quadric estimation by LMedS. In the experimental results, we have demonstrated that the proposed method can achieve a precise camera pose estimation and scene geometry recovery without bundle adjustment. In addition, virtual objects have been inserted in the real images by using the camera trajectories.