• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.158-159
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• 2005

The paper presents a method for location of subsurface UXOs. The approach utilities gradient interpretation techniques (analytic signal, horizontal gradient and Euler methods) to locate the objects. Then, linear least-squares technique, we obtain the magnetization location of the sources. We demonstrate the practical utility of the method using marine magnetic field data.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.11
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• pp.66-72
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• 2014

Histogram of oriented gradient (HOG) feature is widely used in vision-based pedestrian detection. The interpolation is the most important technique in HOG feature calculation to provide high detection rate. In interpolation technique of HOG feature calculation, two nearest orientation bins to gradient orientation for each pixel and the corresponding weights are required. In this paper, therefore, an efficient gradient orientation bin and weight calculation circuit for HOG feature is proposed. In the proposed circuit, pre-calculated values are defined in tables to avoid the operations of tangent function and division, and the size of tables is minimized by utilizing the characteristics of tangent function and weights for each gradient orientation. Pipeline architecture is adopted to the proposed circuit to accelerate the processing speed, and orientation bins and the corresponding weights for each pixel are calculated in two clock cycles by applying efficient coarse and fine search schemes. Since the proposed circuit calculates gradient orientation for each pixel with the interval of $1^{\circ}$ and determines both orientation bins and weights required in interpolation technique, it can be utilized in HOG feature calculation to support interpolation technique to provide high detection rate.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.8
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• pp.2611-2625
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• 1996

A numerical method on multi-block technique by Bi-CGSTAB(Bi-Conjugate Gradient STABilized) solver has been proposed. The present multi-block technique can reduce the numerical manipulation greatly because the common regions at the interface of each block are not necessary. In order to test the computational performance of present multi-block technique, the flow characteristics in a T type duct system and a N type duct system have been investigated by three kinds of methods such as the single-block method, the previous multi-block technique and the multi-block technique with Bi-CGSTAB solver. The results indicated that the required CPU time by present multi block technique was shorter than that of other two numerical methods and the convergency history was shown very stable at the present multi-block technique.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.1
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• pp.63-73
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• 2021

This paper presents a algorithm for automatic target recognition robust to the influence of the flame in order to track the target by EOTS(Electro-Optical Targeting System) equipped on UAV(Unmanned Aerial Vehicle) when there is aerial target or marine target with flame at the same time. The proposed method converts infrared images of targets and flames into a gradient vector field, and applies each gradient magnitude to a polynomial curve fitting technique to extract polynomial coefficients, and learns them in a shallow neural network model to automatically recognize targets and flames. The performance of the proposed technique was confirmed by utilizing the various infrared image database of the target and flame. Using this algorithm, it can be applied to areas where collision avoidance, forest fire detection, automatic detection and recognition of targets in the air and sea during automatic flight of unmanned aircraft.

• The Korean Journal of Cytopathology
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• v.15 no.2
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• pp.86-91
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• 2004

Liquid-Based Uterine Cervicovaginal Cytology is known to be a sensitive and effective screening method for cervical neoplasm $MonoPrep^{TM},\;ThinPrep^{TM},\;and\;SurePath^{TM}$ methods have been recently used as Liquid-Based Uterine Cervicovaginal Cytology techniques, and the $SurePath^{TM}$ method has been used in Sung-Yoon Reference Laboratory since 2003. The goal of Liquid-Based Uterine Cervicovaginal Cytology is to separate cervical epithelial cells from non-target cells, red blood cells and neutrophils. This report describes a study which evaluated cellularity, stainablilty, and cellular changes of epithelial cels in samples processed using a manual technique as compared to samples processed using $SurePath^{TM}$ automated method. The samples processed by means of a manual technique contained a cellularity of epithelial cells similar to that of the samples processed using the $SurePath^{TM}$ automated method. In addition, we compared variable density gradient reagents, including dextran, dextrose, and sucrose, to $SurePath^{TM}$ gradient media in order to evaluate cell fractionation and cellularity of epithelial cells. 10% dextran of gradient media shows good fractionation. The samples processed with 10% dextran demonstrated sufficient cellularity of epithelial cells and shows the fewest cellular changes. In conclusion, using a manual technique on these samples is easier to read than those results obtained using the $SurePath^{TM}$ automated method.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.1
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• pp.1-4
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• 2003

In the present work we consider morphological structure of the faces of BGO crystals grown by Czochralski technique under the conditions of low temperature gradient (0.1~1 deg/cm) and interconnection between the morphological features of faces at the crystallization front and the formation of defects within the crystal volume. It is demonstrated that the {112} faces retain stability while the growing surface deviates from the crystallographic (112) plane up to 1 degree. At larger deviation, the region of the stable facet growth passes either to the region of macrosteps or to the region of normal growth. depending on conditions.

• Journal of Korea Multimedia Society
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• v.17 no.10
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• pp.1141-1149
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• 2014

Recently, various methods to effectively eliminate the noise are researched in image processing techniques. However, the conventional noise filtering techniques, which remove most of the noise, are less efficient for remained noise detection after filtering due to exploiting no face feature information. In this paper, we proposed a feature vector generation technique in the mouth region by distinguishing and revising the remained noise through gradient correction, when the outline is extracted after performing noise filtering.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.2C
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• pp.201-208
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• 2003

The error concealment is very useful technique for real-time communication, such as video conference. In this paper. we propose the error concealment technique to minimize discontinuity of block boundary in consideration of the fact that human visual system is sensitive to discontinuity. The error concealment for each loss block is performed by extended block matching method based on gradient difference. In the simulation result, performance improvement for the proposed technique is on the average 1.32㏈ in comparison with the conventional technique.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.2-4
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• 2021

In a distributed machine learning system, sharing gradients was considered safe because it did not share original training data. However, recent studies found that malicious attacker could completely restore the original training data from shared gradients. Gradient Leakage Attack is a technique that restoring original training data by exploiting theses vulnerability. In this study, we present the image transformation method based on Discrete Cosine Transform to defend against the Gradient Leakage Attack on the federated learning setting, which training in local devices and sharing gradients to the server. Experiment shows that our image transformation method cannot be completely restored the original data from Gradient Leakage Attack.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.733-734
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• 2016

This study proposes a novel approach for ground segmentation of 3D point cloud. We combine two techniques: gradient threshold segmentation, and mean height evaluation. Acquired 3D point cloud is represented as a graph data structures by exploiting the structure of 2D reference image. The ground parts nearing the position of the sensor are segmented based on gradient threshold technique. For sparse regions, we separate the ground and nonground by using a technique called mean height evaluation. The main contribution of this study is a new ground segmentation algorithm which works well with 3D point clouds from various environments. The processing time is acceptable and it allows the algorithm running in real time.