• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.34-42
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• 2005

This paper presents the optimum initial design containing the first and third order properties of the three-group zoom system using lens modules, and the real lens design of the system. The optimum initial design with focal length range of 4.3 mm to 8.6 mm is derived by assigning appropriate first and third order quantities to each module along with the specific constraints required for the system. An initial real lens selected for each group has been designed to match its focal length and the first orders into those of the each lens modules, and then combined to establish an actual zoom system by adjusting the air space between the groups at all zoom positions. The combination of the separately designed groups results in a system which satisfies the first order properties of the zoom system composed of the original lens modules. As a result, by residual aberration correction, we could obtain a zoom system useful in compact digital zoom cameras and mobile phone cameras employing the rear focus method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.1024-1031
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• 2012

In this paper, FMCW type radar level transmitter using correlation analysis method is implemented for precise distance measurement of cargo tank. FMCW type radar level transmitter is the device for distance measurement which calculates the distance by analyzing the beat frequency, that is, the frequency difference between Tx and RX signal from radar antenna using Fast Fourier Transform(FFT), but compensated algorithm like Zoom FFT is needed for the improvement of the frequency precision because the frequency precision of FFT is limited depending on sampling frequency and the number of sampling data. In case of Zoom FFT, the number of sampling data and noisy signal are the main factor influencing the measurement accuracy of Zoom FFT like FFT. Therefore, in order to overcome the limited environment and achieve the precise measurement, correlation coefficient is used for the distance measurement and the errors of measurement are verified to be in the range of ${\pm}1mm$.

• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.81-87
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• 1997

This paper presents the optimum initial design containing the first and third order properties of the four-group video camera zoom system using lens modules, and its real lens design. The optimum initial design with focal length range of 6.1693 to 58.4065 mm is derived by assigning appropriate first order quantities and third order aberrations to each module along with the specific constraints required for optimization. By scaling the focal length of each lens group, an initial real lens selected for each group has been designed to match its focal length into that of the each lens module, and then combined to establish an actual zoom system by adjusting the air space between the groups at all zoom positions. The combination of the separately designed groups results in a system which satisfies the first order properties of the zoom system consisting of original lens modules. As a result, by residual aberration correction, we could obtain a zoom system useful in video zoom camera employing the rear focus method.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.5
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• pp.229-234
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• 2010

This paper proposed the acoustic signal processing techniques, which are applicable even in the shallow river, and will enhance the frequency resolution of the ADCP (Acoustic Doppler Current profiler). ADCP is a device that measures the velocity of a moving fluid. ADCP, in general, can be operated at ~300 Khz of center frequency due to no depth limit in the sea. However, it can hardly be used due to water depth of 30cm or shallower during the dry season in the river. Therefore, existing signal processing methods are not suitable to use in the shallow river. We are proposing an alternative acoustic signal processing method using Zoom FFT. Simulation results show that errors are reduced ${\pm}62\;cm/s$ in theory, and ${\pm}93\;cm/s$ in the experiment. The existing algorithm could not estimate the current speed at the shallow river below 30 cm, but proposed algorithm estimated the current speed that was faster than 20 cm/s at the shallow river below 30 cm.

• Korean Journal of Optics and Photonics
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• v.17 no.5
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• pp.420-429
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• 2006

In the zoom lens of digital still cameras with the variation of the image plane generated by various symmetric error factors such as curvature, thickness and refractive index error of each lens surface about the optic axis, we induce a theoretical condition to fix constantly the image plane by translating the compensator group of the zoom lens by using the Gaussian bracket. We confirm the validity of this condition by using three examples of general zoom lens types with 3, 4, and 5 groups, respectively. When these error factors are randomly changed within the range of tolerance according to the Monte Carlo method, we verify that the distributions of the degree of moving of the compensator are normal distributions at three zoom lens types. From capability analysis using these results, we theoretically propose the method estimating the standard deviation, that is, sigma-level, as a function of the maximum movement of the compensator.

• Journal of Biomedical Engineering Research
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• v.27 no.4
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• pp.189-196
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• 2006

Micro computed tomography (micro-CT) has been used for in vivo animal study owing to its noninvasive and high spatial resolution capability. However, the sizes of existing detectors for micro-CT systems are too small to obtain whole-body images of a small animal object with $\sim$10 micron resolution and a part of its bones or other organs should be extracted. So, we have introduced the zoom-in micro-tomography technique which can obtain high-resolution images of a local region of an live animal object without extracting samples. In order to verify our zoom-in technique, we performed in vivo animal bone study. We prepared some SD (Sprague-Dawley) rats for making osteoporosis models. They were divided into control and ovariectomized groups. Again, the ovariectomized group is divided into two groups fed with normal food and with calcium-free food. And we took 3D tomographic images of their femurs with 20 micron resolution using our zoom-in tomography technique and observed the bone changes for 12 weeks. We selected ROI (region of interest) of a femur image and applied 2D FDT (fuzzy distance transform) to measure the trabecular bone thickness. The measured results showed obvious bone changes and big differences between control and ovariectomized groups. However, we found that the reliability of the measurement depended on the selection of ROI in a bone image for thickness calculation. So, we extended the method to 3D FDT technique. We selected 3D VOI (volume of interest) in the obtained 3D tomographic images and applied 3D FDT algorithm. The results showed that the 3D technique could give more accurate and reliable measurement.

• Journal of Practical Engineering Education
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• v.14 no.3
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• pp.535-541
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• 2022

Zoom has been most popularly used as a non-face-to-face online class tool since COVID19, but due to the recent spread of the metaverse, the use of the metaverse platform is increasing. In particular, since a metaverse platform 'Spatial' provides online classroom creation and various learning functions, and various interactions between instructors and learners or learners and learners are possible, it is highly likely to be used in university classes. Since Zoom and Spatial each have their own strengths and weaknesses for the purpose of class use, it is necessary to find out the strengths and weaknesses of each by comparing and analyzing the learner's experience in class use. In this study, a quantitative analysis of usability, immersion, and satisfaction and a qualitative analysis of individual opinions were performed in order to compare and analyze the learner's experience. SUS (System Usability Scale) was used for usability evaluation, and Magnitude Estimation method was used for immersion and satisfaction evaluation. Thirty-five people who had participated in classes using Zoom and Spatial participated as subjects in this study. Zoom was higher than Spatial at the significance level of 0.05 in usability and satisfaction. On the other hand, the immersion in class was higher in Spatial than in Zoom. Since Spatial provides online classroom creation and various learning functions, and provides various interactions and fun elements between instructors and learners or learners and learners, the immersion in classes was high. If the user interface and interaction of Spatial are improved in the future, it is judged that it can be used as an effective online teaching tool that can replace zoom in university classes.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.11a
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• pp.165-171
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• 2003

We have developed Virtual Reality Simulator MMI for operator training. MMI communicates with server model and client PC through OPCServer. We used Dataplant for Soft Panel and Simdiagram which shows more sophisticated and reality colors. We used vector method for MCR images instead of conventional bit-map method to protect images during zoom in and zoom out. VBScript and Components were used for real movements and images of instruments. VRMCR panel is consisted of 12 groups and designed to accommodate user's convenience.

• Korean Journal of Optics and Photonics
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• v.34 no.2
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• pp.66-71
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• 2023

Zoom lenses are now starting to be applied to mobile-phone cameras as well. A zoom lens applied to a mobile-phone camera is mainly used to capture images in the telephoto range. Such an optical system has a long focal length, similar to that of a high-magnification zoom optical system, so the position of the imaging device also shifts significantly, due to manufacturing errors of the lenses and mechanical parts. In the past, the positional shift of the imaging device was corrected by moving the first lens group and the total optical system, but this paper confirms that the position of the imaging device can be corrected by selecting any two moving lens groups. However, it is found that more distance must be secured in the front and rear of a moving lens group for this purpose.

• Journal of the Korea Computer Graphics Society
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• v.29 no.3
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• pp.127-135
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• 2023

Accurate segmentation of histopathology whole slide images (WSIs) is a crucial task for disease diagnosis and treatment planning. However, conventional automated segmentation algorithms may not always be applicable to WSI segmentation due to their large size and variations in tissue appearance, staining, and imaging conditions. Recent advances in interactive segmentation, which combines human expertise with algorithms, have shown promise to improve efficiency and accuracy in WSI segmentation but also presented us with challenging issues. In this paper, we propose a novel interactive segmentation method, ZoomISEG, that leverages multi-resolution WSIs. We demonstrate the efficacy and performance of the proposed method via comparison with conventional single-scale methods and an ablation study. The results confirm that the proposed method can reduce human interaction while achieving accuracy comparable to that of the brute-force approach using the highest-resolution data.