• 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

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.421-426
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• 2009

This paper presents vibration analysis of maskless exposure module in Printed Circuit Board (PCB) manufacturing system. In order to complete exposure process in PCB, masking type module has been widely used in electronics industries. However, masking process confronts some limitations of application due to higher production cost for masking as well as lower printing resolution. Therefore, maskless exposure module is started to be in the spotlight for flexible production system to meet the needs of fabrication in variable patterns at low cost. Since maskless exposure process adopts direct patterning to PCB, vibration problems become more critical compared to conventional masking type process. Moreover, movements of exposure engine as well as stage generate vibration sources in the system. Thus, it is imperative to analyze the vibration characteristics for the maskless exposure module to improve the quality and accuracy of PCB. In this study, vibration analysis using the Finite Element Analysis is conducted to identify the critical structural parts deteriorating vibration performance. Also, Experimental investigations are conducted by single/dual encoder measurement process under the operating module speed. Measurement points of vibration are selected by three places, which are base of stage, exposure engine and top of stage, to check the effect of vibration from the exposure engine. Comparisons between analysis results and experimental measurement are conducted to confirm the accuracy of analysis results including the developed FE model. Finally, this studies show feasibility of optimal design using the developed FE analysis model.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.12
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• pp.1322-1328
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• 2009

This paper presents vibration analysis of maskless exposure module in printed circuit board(PCB) manufacturing system. In order to complete exposure process in PCB, masking type module has been widely used in electronics industries. However, masking process confronts some limitations of application due to higher production cost for masking as well as lower printing resolution. Therefore, maskless exposure module is started to be in the spotlight for flexible production system to meet the needs of fabrication in variable patterns at low cost. Since maskless exposure process adopts direct patterning to PCB, vibration problems become more critical compared to conventional masking type process. Moreover, movements of exposure engine as well as stage generate vibration sources in the system. Thus, it is imperative to analyze the vibration characteristics for the maskless exposure module to improve the quality and accuracy of PCB. In this study, vibration analysis using the finite element analysis is conducted to identify the critical structural parts deteriorating vibration performance. Also, Experimental investigations are conducted by single/dual encoder measurement process under the operating module speed. Measurement points of vibration are selected by three places, which are base of stage, exposure engine and top of stage, to check the effect of vibration from the exposure engine. Comparisons between analysis results and experimental measurement are conducted to confirm the accuracy of analysis results including the developed FE model. Finally, this studies show feasibility of optimal design using the developed FE analysis model.

• 전기의세계
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• v.30 no.4
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• pp.227-230
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• 1981

The variation of sheet resistance and the reduction of masking oxide thickness with the flow rate of nitrogen gas has been measured in Boron predeposition process with Planar Diffusion source, BN-975. At 900.deg. C, the sheet resistance varied as much as 75% when the nitrogen flow rate was changed from 0.4 liters/min to 2.0 liters/min. At 975.deg. C, however, only 12% of sheet resistance variation was observed under the same flow rate change. The reduction of masking oxide thickness at 975.deg. C for a 5 min predeposition was 600 nm when the nitrogen flow rate was 0.4 liters/min. When the flow rate incresased to 1.9 liters/min, however, only 100nm of masking oxide was consumed in a similar predeposition process.

• ETRI Journal
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• v.33 no.2
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• pp.267-274
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• 2011

This paper proposes an efficient masking method for the block cipher SEED that is standardized in Korea. The nonlinear parts of SEED consist of two S-boxes and modular additions. However, the masked version of these nonlinear parts requires excessive RAM usage and a large number of operations. Protecting SEED by the general masking method requires 512 bytes of RAM corresponding to masked S-boxes and a large number of operations corresponding to the masked addition. This paper proposes a new-style masked S-box which can reduce the amount of operations of the masking addition process as well as the RAM usage. The proposed masked SEED, equipped with the new-style masked S-box, reduces the RAM requirements to 288 bytes, and it also reduces the processing time by 38% compared with the masked SEED using the general masked S-box. The proposed method also applies to other block ciphers with the same nonlinear operations.

• Journal of Information Processing Systems
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• v.19 no.6
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• pp.767-777
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• 2023

In modern society, user privacy is emerging as an important issue as closed-circuit television (CCTV) systems increase rapidly in various public and private spaces. If CCTV cameras monitor sensitive areas or personal spaces, they can infringe on personal privacy. Someone's behavior patterns, sensitive information, residence, etc. can be exposed, and if the image data collected from CCTV is not properly protected, there can be a risk of data leakage by hackers or illegal accessors. This paper presents an innovative approach to "machine learning based reversible chaotic masking method for user privacy protection in CCTV environment." The proposed method was developed to protect an individual's identity within CCTV images while maintaining the usefulness of the data for surveillance and analysis purposes. This method utilizes a two-step process for user privacy. First, machine learning models are trained to accurately detect and locate human subjects within the CCTV frame. This model is designed to identify individuals accurately and robustly by leveraging state-of-the-art object detection techniques. When an individual is detected, reversible chaos masking technology is applied. This masking technique uses chaos maps to create complex patterns to hide individual facial features and identifiable characteristics. Above all, the generated mask can be reversibly applied and removed, allowing authorized users to access the original unmasking image.

• 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 Biosystems Engineering
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• v.40 no.1
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• pp.19-27
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• 2015

Purpose: A system to measure the visibility of agricultural tractor operators was designed and evaluated according to ISO standards, and a blind area diagram around the tested tractor was created based on the manual method recommended by the National Institute for Occupational Safety and Health (NIOSH). Methods: A visibility measurement system was designed and evaluated based on the ISO 5006 and ISO 5721-1 standards. Two bulbs used to simulate the operator's eyes were mounted on a bar with a supporting frame. A wooden frame was used to determine the seat index point position. The 12-m visibility test circle was divided into six sectors of vision, and the test tractor was placed at the center of the circle. Artificial light was supplied in the darkened environment, and shadow or masking effects were measured manually around the 12-m circle. Results: When the bulbs were placed at the operator's eye level, front visibility was good; no masking was found in the "A" vision sector, but larger masking widths were found in the "B" and "C" vision sectors. Since the masking width exceeded 700 mm, additional tests, such as movement of the light sources to both sides of the operator's eye level, were performed. Less than six masking effects were found in the semi-circle of vision to the front, and more than one masking was found in the "B" and "C" visual fields. The minimum distance between the centers of two masking effects exceeded 2500 mm when measured as a chord on the semi-circle of vision. A blind area diagram was created to define the exact nature of the blind spots and mirror visibility. Conclusions: Visibility evaluation is an effective way to enable proper and safe operation for agricultural tractor operators. Inclusion of this visibility evaluation test in the general testing process might aid tractor manufacturers.

• Korean Journal of Cognitive Science
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• v.22 no.4
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• pp.365-384
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• 2011

A recent study of visual working memory(VWM) under a change detection paradigm proposed an idea that the comparison process of VWM representations against incoming perceptual inputs can be performed more rapidly than the process of forming durable memory representations into VWM. To test this hypothesis, we compared the size of interference effect caused by pattern-backward masks following after either the sample(sample-mask condition) or test items (test-mask condition). In Experiment 1, subjects performed a color change detection task for four colored-boxes, and pattern masks with mask-onset asynchronies(MSOA) of either 64ms or 150ms followed each item location either after the sample or after the test items. The change detection accuracy was both comparable in the sample-mask condition regardless of the MSOAs, whereas the accuracy in the trials with a MSOA of 150ms was substantially higher than the MSOA of 65ms in the test-masking condition. In Experiment 2, we manipulated setsizes to 1, 2, 3, 4 items and also MSOAs to 117ms, 234ms, 350ms, 484ms and compared the pattern of interference across a variety of setsize and MSOA conditions. The sample-mask condition yielded a pattern of masking interference which became more evident as the setsize increases and as the MSOA was shorter. However, this pattern of interference was less apparent in the test-mask condition. These results indicate that the comparison process between remembered items in VWM and perceptual inputs is less vulnerable to interference from pattern-backward masking than VWM consolidation is, and thus support for the recent idea that the comparison process in VWM can be performed very fast and accurately.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.369-372
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• 2003

In this paper, we propose impr oved binary tree vector quantization based on spatial sensitivity which is one of the human visual properties. We combine the weights based on spatial masking effect according to changes of three primary colors in blocks of images with the process of splitting nodes using eigenvector in binary tree vector quantization. The test results show that the proposed method generates the quantized images with fine color and performs better than the conventional method in terms of clustering the similar regions. Also the proposed method can get the better result in subjective qualify test and PSNR.