• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.154-154
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• 2021

Since the development of Bubble Image Velocimetry (BIV) technique as the complementary technique of Particle Image Velocimetry (PIV), the application of digital imaging technique in the field of hydraulic and coastal engineering increased rapidly. BIV works very well in multi-phase flow (air-water) flows where the PIV technique doesn't. However, the velocity field obtained from BIV technique often resulted in a velocity vector on the outside of the flow (false velocity) since the Field of View (FOV) usually not only cover the air-water flow but also the area outside the flow. In this study, a simple technique of post processing velocity field was developed. This technique works based on the average of the pixel value in the interrogation area. An image of multi-phase flow of wave overtopping was obtained through physical experiment using BIV technique. The velocity calculation was performed based on the similar method in PIV. A velocity masking technique developed in this study then applied to remove the false velocity vector. Result from non-masking, manually removed and auto removed false velocity vector were presented. The masking technique show a similar result as manually removed velocity vector. This method could apply in a large number of velocity field which is could increase the velocity map post-processing time.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.180-183
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• 2002

In this paper, we propose new unsharp masking technique based on the multiscale gradient planes. The unsharp masking technique is implemented as a high-pass filter and improves the sharpness of degraded images. However, the conventional unsharp masking enhances the noise component simultaneously. To reduce the noise influence, we introduce the edge information from the difference of the gradient values between two consecutive scales of the multiscale gradient. The multiscale gradient indicates the presence of image edges as the ratio between the gradients between two different scales by its multiscale nature. The noise reduction of the proposed method does not depend on the variance of images and noises. In experiment, we demonstrate enhancement results for blurred noisy images and compare with the conventional cubic unsharp masking technique.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.985-988
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• 2007

This paper presents techniques to make image enhancement using unsharp masking. It is the technique to make image enhancement by automatically find the three parameters that makes hard to use the unsharp mask technique. To optimize the three parameters(Threshold, Amount, Radius), at first classify the pixels in the image to three groups, and then according to the groups, apply the unsharp mask to the image differently. We experimented and analyzed the rate of image enhancement by comparing images which is enhanced by human and which is enhanced by proposed technique.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.4
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• pp.923-941
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• 2017

A side-channel attack is a method of attacking a cipher based on physical information of a cryptographic device. The masking method, which is a typical method overcoming this attack, is a method of calculating an arbitrary masking value at the round intermediate value through rounds. Thus, it is difficult to guess the intermediate value by the side-channel attack, but if the masking operation is applied to all rounds of the encryption algorithm, the encryption process may become overloaded. Therefore, it is practical to use a reduced-round masking technique that applies a masking technique to only a part of the cipher for lightweight equipment such as Internet of Things(IoT) and wearable devices. In this paper, we describe a Hamming weight filtering for SIMON family with reduced-round masking technique and it is shown that first round key recovery is possible through actual programming.

• Journal of Multimedia Information System
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• v.4 no.2
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• pp.65-73
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• 2017

This paper proposes a method to improve the image quality by designing Unsharp Mask Filter (UMF) based on Retinex theory which controls the frequency pass characteristics adaptively. Conventional unsharp masking technique uses blurring image to emphasize sharpness of image. Unsharp Masking(UM) adjusts the original image and sigma to obtain a high frequency component to be emphasized by the difference between the blurred image and the high frequency component to the original image, thereby improving the contrast ratio of the image. In this paper, we design a Unsharp Mask Filter(UMF) that can process the contrast ratio improvement method of Unsharp Masking(UM) technique with one filtering. We adaptively process the contrast ratio improvement using Unsharp Mask Filter(UMF). We propose a method based on Retinex theory for adaptive processing. For adaptive filtering, we control the weights of Unsharp Mask Filter(UMF) based on the human visual system and output more effective results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.268-271
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• 2008

A sound-masking technique was applied to the urban public spaces with multiple noises in order to reduce the annoyance of the construction and traffic noise. In addition, the effects of masking system were investigated in order to improve the soundscape. In several urban spaces, building construction and nearby road traffic noise were recorded using a head and torso simulator and sound quality (SQ) system which specifies the spectral and temporal aspects of the noises. The sound-masking system which consists of the distributed speakers and control devices was applied to the boundaries of the construction sites. Synthesized masking sounds were produced with consideration of SQ characteristics of the multiple noise. Subjective evaluations on the soundscape were conducted to verify effectiveness of the system under the conditions with and without the masker sounds.

• Journal of Korea Multimedia Society
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• v.21 no.2
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• pp.108-116
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• 2018

In this paper, we propose an image enhancement method based on Multi-Scale Retinex theory that designs Unsharp Masking Filter (UMF) and emphasizes the contrast ratio adaptively. Unsharp Masking (UM) technique emphasizes image sharpness and improves contrast ratio by adding high frequency component to the original image. The high frequency component is obtained by differentiating between original image and low frequency image. In this paper, we present how to design an UMF kernel and to adaptively apply it to increase the contrast ratio according to multi-scale retinex theory which resembles human visual system. Experimental results show that the proposed method has better quantitative performance indexes such as PSNR, ambe & SSIM and better qualitative feature like halo artifact suppression.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.1
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• pp.5-15
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• 2016

Power analysis attacks are techniques to analyze power signals to find out the secrets when cryptographic algorithm is performed. One of the most famous countermeasure against power analysis attacks is masking methods. Masking types are largely classified into two types which are boolean masking and arithmetic masking. For the cryptographic algorithm to be used with boolean and arithmetic masking at the same time, the converting algorithm can switch between boolean and arithmetic masking. In this paper we propose an algorithm for switching from boolean to arithmetic masking using storage size at less cost than ones. The proposed algorithm is configured to convert using the look-up table without the least significant bit(LSB), because of equal the bit of boolean and arithmetic masking. This makes it possible to design a converting algorithm compared to the previous algorithm at a lower cost without sacrificing performance. In addition, by applying the technique at the LEA it showed up to 26 percent performance improvement over existing techniques.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.834-838
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• 2004

We report on a simple method of fabricating multimode transflective liquid crystal displays (LCDs) using the photoalignment technique. Using a self-masking process of ultraviolet light by the reflector as a photomask as well as a reflective mirror, the periodic multimode is obtained with no additional fabrication processes. Moreover, variations of the cell gap are not required for such trasflective LCDs

• Publications of The Korean Astronomical Society
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• v.8 no.1
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• pp.105-117
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• 1993

Astronomical plates have a very large density range (dynamical range). Many exposed astronomical photographic plates do not provide detailed structures for very high densities, and some include hidden images for very low densities. The former can be fixed through 'Unsharp Masking' technique and the latter through 'Image Amplification' technique. Besides, we can find intrinsic colors of celestial bodies through 'Tri Color Composition' technique. Images of several plates which were observed from Sobaek Observatory with 61cm telescope are reproduced by the three kinds of image reproducing techniques. As reproduced image examples, we display an Orion nebula and a waxing crescent moon images through unsharp masking technique and an M81 image through image amplification technique. An Orion nebula and a Dumbbell nebula images are also given as results of tri color composition technique.