• KIPS Transactions on Software and Data Engineering
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• v.6 no.1
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• pp.23-28
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• 2017

Shape from focus (SFF) is a technique used to reconstruct 3D shape of objects from a sequence of images obtained at different focus settings of the lens. In this paper, a new shape from focus method for 3D reconstruction of microscopic objects is described, which is based on gradient operator in Mathematical Morphology. Conventionally, in SFF methods, a single focus measure is used for measuring the focus quality. Due to the complex shape and texture of microscopic objects, single measure based operators are not sufficient, so we propose morphological operators with multi-structuring elements for computing the focus values. Finally, an optimal focus measure is obtained by combining the response of all focus measures. The experimental results showed that the proposed algorithm has provided more accurate depth maps than the existing methods in terms of three-dimensional shape recovery.

• Annual Conference on Human and Language Technology
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• 2013.10a
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• pp.146-151
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• 2013

이중언어 사전 구축 방법을 평가하는 방법에는 정확률, 재현율, MRR(Mean Reciprocal Rank) 등이 있다. 이들 방법들은 평가 집합에 있는 대역어를 정확하게 찾는 것에 초점을 맞추고 있다. 그러나 어떤 대역어가 얼마나 많이 사용되는지는 전혀 고려하지 않는다. 즉 자주 사용되는 대역어를 빨리 찾을 수 있는 방법이 좋은 방법이라고 말할 수 있다. 이와 같은 문제를 해결하기 위해서 본 논문에서는 이중언어 사전 구축의 새로운 평가 방법인 등급 재현율을 제안한다. 등급 재현율(rated recall)은 대역어가 학습 말뭉치에 나타난 정도를 반영하는 재현율이며, 자주 사용되는 대역어를 얼마나 정확하게 찾는지를 파악할 수 있는 좋은 측도이다. 본 논문에서는 문맥벡터와 중간언어를 이용한 이중언어 사전 구축 시스템의 성능을 평가하고 기존의 방법과 비교 분석하였다.

• The KIPS Transactions:PartC
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• v.14C no.5
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• pp.439-452
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• 2007

We study on the privacy preserving data mining, PPDM for short, by using randomization. The theoretical PPDM based on the secure multi-party computation techniques is not practical for its computational inefficiency. So we concentrate on a practical PPDM, especially randomization technique. We survey various privacy measures and study on the privacy preserving mining of association rules by using randomization. We propose a new randomization operator, binomial selector, for privacy preserving technique of association rule mining. A binomial selector is a special case of a select-a-size operator by Evfimievski et al.[3]. Moreover we present some simulation results of detecting an appropriate parameter for a binomial selector. The randomization by a so-called cut-and-paste method in [3] is not efficient and has high variances on recovered support values for large item-sets. Our randomization by a binomial selector make up for this defects of cut-and-paste method.

• Journal of the Semiconductor & Display Technology
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• v.13 no.2
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• pp.23-28
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• 2014

For the reconstruction of three-dimensional (3D) shape of microscopic objects through shape from focus (SFF) methods, usually a single focus measure operator is employed. However, it is difficult to compute accurate depth map using a single focus measure due to different textures, light conditions and arbitrary object surfaces. Moreover, real images with diverse types of illuminations and contrasts lead to the erroneous depth map estimation through a single focus measure. In order to get better focus measurements and depth map, we have combined focus measure operators by using genetic algorithm. The resultant focus measure is obtained by weighted sum of the output of various focus measure operators. Optimal weights are obtained using genetic algorithm. Finally, depth map is obtained from the refined focus volume. The performance of the developed method is then evaluated by using both the synthetic and real world image sequences. The experimental results show that the proposed method is more effective in computing accurate depth maps as compared to the existing SFF methods.

• Journal of the Semiconductor & Display Technology
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• v.18 no.3
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• pp.66-71
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• 2019

In shape from focus (SFF) methods, the quality of image focus volume plays a vital role in the quality of 3D shape reconstruction. Traditionally, a linear 2D filter is applied to each slice of the image focus volume to rectify the noisy focus measurements. However, this approach is problematic because it also modifies the accurate focus measurements that should ideally remain intact. Therefore, in this paper, we propose to enhance the focus volume adaptively by applying 3-dimensional weighted least squares (3D-WLS) based regularization. We estimate regularization weights from the guidance volume extracted from the image sequences. To solve 3D-WLS optimization problem efficiently, we apply a technique to solve a series of 1D linear sub-problems. Experiments conducted on synthetic and real image sequences demonstrate that the proposed method effectively enhances the image focus volume, ultimately improving the quality of reconstructed shape.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.11-16
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• 2010

This paper compares and studies scheduling methods to reduce jitter in real-time control systems. While previous research has focused on dynamic-priority scheduling schemes, this paper focuses on fixed-priority scheduling which is more widely used. It is pointed out that previously defined jitter measures might not be useful in enhancing the control performance of a real-time task because the measures are relative values. We present a new jitter measure and a new scheduling scheme for fixed-priority tasks. The experimental results through simulation show that the new scheduling scheme reduces jitter and enhances control performance.

• Journal of the Korean Data and Information Science Society
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• v.21 no.3
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• pp.535-546
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• 2010

There are two methods in grouping customers for micro marketing promotion. The one is based on how much they paid and the other is based on how many times they purchased. In this study we are interested in the repurchase probability of customers. By analysing the customer's transaction data and demographic data, we develop a forecasting model of repurchase and make epurchase indexes of them. As a modeling tool we use the logistic regression model. Finally we categorize the customers into five groups in according to their repurchase indexes so that we can control customers effectively and get higher profit.

• Communications of Mathematical Education
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• v.36 no.4
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• pp.589-610
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• 2022

This study aimed to derive pedagogical implications by comparing and analyzing how the concept of pi is taught in 10 different elementary mathematics textbooks, which are scheduled to be applied from 2023. We developed a textbook analysis framework by previous studies on the concept of pi and the teaching of pi, and analyzed in terms of three instructional elements (i.e. inferring conceptsof pi, understanding properties of pi, and applying relationships). We derived the need to emphasize various contexts for estimation of pi, presentation of problem situations that provide motivation to actually measure diameters and circumferences, providing an opportunity to explore the properties of measurement, and an experience the flexibility of selecting an approximate value of pi. Based on the above conclusions and pedagogical implications through the research results., we suggested ways to teach the concept of pi in elementary mathematics and improvement points for developing textbooks focusing on the context of introduction of pi and the use of technological tools.