• Journal of the Korea Institute of Information Security & Cryptology
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• v.7 no.2
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• pp.55-72
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• 1997

This paper presents a digital signature scheme for facsimile document which directly embeds a signature onto the document. We use multiple reference lines which have been scanned just before and modify each distance of changing pels both on the reference line specified by key and on the coding line with a single bit of the signature data. The time to take in signature is reduced by spreading of signature. Non-repudiation in origin, the 3rd condition of digital signature is realized by proposed digital signature scheme. The transmitter embeds the signature secretly and transfers it, and the receiver makes a check of any forgery on the signature and the document. This scheme is compatible with the ITU-T.4(CCITT G3 or G4 facsimile standards). The total amount of data transmitted and the image quality are about the same to that of the original document, and thus a third party notices that no signature is embedded on the document.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.3
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• pp.135-144
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• 2003

This work proposes on-chip full CMOS current and voltage references for high-speed mixed-mode circuits. The proposed current reference circuit uses a digital-domain calibration method instead of a conventional analog calibration to obtain accurate current values. The proposed voltage reference employs internal reference voltage drivers to minimize the high-frequency noise from the output stages of high-speed mixed-mode circuits. The reference voltage drivers adopt low power op amps and small- sized on-chip capacitors for low power consumption and small chip area. The proposed references are designed, laid out, and fabricated in a 0.18 um n-well CMOS process and the active chip area is 250 um x 200 um. The measured results show the reference circuits have the power supply variation of 2.59 %/V and the temperature coefficient of 48 ppm/$^{\circ}C$ E.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1986.04a
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• pp.138-141
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• 1986

After various oscillators have been reviewed, cesium beam frequency standards are recommended as the KRF(Korea Reference Frequency) source. We have investigated the characteristics of the SP-12M coaxial cable to find out whether it is usable for the network synchronization.

• Journal of the Korea Fashion and Costume Design Association
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• v.12 no.2
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• pp.67-73
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• 2010

Whole process of textile printing is made by computer and it remarkably improves environment problem. This digital textile printing is becoming next step environment friendly textile printing method. But, still now range of textile possible for digital textile printing is limited, and also color analysis according to fiber types is not completed. The ink printed on the fabrics through DTP printer can be absorbed and fixed into textile without any blots by pre-treatment using suitable media solution for fabrics types. The chemical formulation of media solution used in the pre-treatment process varies according to the types of textiles and inks for DTP products. First, I studied reference books or articles about color analysis of digital textile printing. Second, I recorded pre-process, printing, post-process and coloring of silk, wool, nylon at same condition. After that, I analyzed $L^*\;a^*\;b^*$, Total K/S, ${\Delta}E$ and studied color intensity and coloring. According to this study, I suggested particular textile special for coloring and manual for affective coloring control. It showed that the performance of the digital printing on the Silk, Wool and Nylon blend fabrics treated by the media solution developed in this study was better than the one treated by the previous media solution for each single inks.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.10 s.241
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• pp.1119-1129
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• 2005

A new measurement system of wall pressure fluctuations on a rotating machinery, composed of digital recording device, was developed and evaluated. The small-sized digital recording device was attached on the rotating machinery and then was detached for data reduction. In order to obtain the system transfer function of the digital recording system, a dynamic calibration was performed utilizing the signal from a 1/8 inch B&K microphone as input. The time history of the unsteady pressure was then reconstructed from the output of the sensor by using this transfer function. The reconstructed pressure signals showed good agreement with the reference signal in both temporal and spectral sense. This sensor was then used to measure the wall pressure fluctuations on a rotating blade. An array of microphones were installed on the blade in the circumferential and radial directions. Various statistical moments were obtained from the measurement data set. Comparison of these quantities with the existing studies demonstrated satisfactory agreement. These tests give credence to the relevance and reliability of this device for applications in more complicated turbulent rotating machineries.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.1989-2000
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• 2015

In this paper, digital peak current mode control for single phase H-bridge inverters is developed and implemented. The digital peak current mode control is achieved by directly controlling the PWM signals by cycle-by-cycle current limitation. Unlike the DC-DC converter where the output voltage always remains in the positive region, the output of DC-AC inverter flips from positive to negative region continuously. Therefore, when the inverter operates in negative region, the control should be changed to valley current mode control. Thus, a novel control logic circuit is required for the function and need to be analyzed for the hardware to track the sinusoidal reference in both regions. The problem of sub-harmonic instability which is inherent with peak current mode control is also addressed, and then proposes the digital slope compensation in constant-sloped external ramp to suppress the oscillation. For unipolar PWM switching method, an adaptive slope compensation in digital manner is also proposed. In this paper, the operating principles and design guidelines of the proposed scheme are presented, along with the performance analysis and numerical simulation. Also, a 200W inverter hardware prototype has been implemented for experimental verification of the proposed controller scheme.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.46-52
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• 2014

This paper presents a multiple gain controlled digital phase and frequency detector with a fast lock-time. Lock-time of the digital PLL can be significantly reduced by applying proposed adaptive gain control technique. A loop gain of the proposed digital PLL is controlled by three conditions that are very large phase difference between reference and feedback signal, small phase difference and before lock-state, and after lock-state. The simulation result shows that lock-time of the proposed multiple gain controlled digital PLL is 100 times faster than that of the conventional structure with unit gain mode.

• Journal of Korea Multimedia Society
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• v.25 no.8
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• pp.983-990
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• 2022

In this paper, we implemented a hierarchical encryption system using two-step phase-shifting digital holography(PSDH) technology based on XOR and scramble operations. The proposed encryption system is a system that authenticates access through the issuance of an encryption key for access to individual laboratories, department offices, and universities. In the encryption process, we proposed a double encryption method using XOR and scramble operation with digital technology and two-step phase-shifting digital holography with optical technology. In the two-step PSDH process, an new method of determining the reference wave intensity without measuring it by using random common object image gererated from digital encryption process was also proposed. In the decryption process, the process is performed in the reverse order of encryption process. And only when the various key information used in the encryption process is correct, the encrypted information can be decrypted, so that the user can access the desired place. That is, there is a feature that can hierarchically control the space that can be accessed according to the type of key issued in the proposed encryption system. Through the computer simulation, the feasibility of the proposed hierarchical encryption system was confirmed.

• Genomics & Informatics
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• v.21 no.2
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• pp.24.1-24.7
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• 2023

Assays of clinical diagnosis and species identification using molecular markers are performed according to a quantitative method in consideration of sensitivity, cost, speed, convenience, and specificity. However, typical polymerase chain reaction (PCR) assay is difficult to quantify and have various limitations. In addition, to perform quantitative analysis with the quantitative real-time PCR (qRT-PCR) equipment, a standard curve or normalization using reference genes is essential. Within the last a decade, previous studies have reported that the digital PCR (dPCR) assay, a third-generation PCR, can be applied in various fields by overcoming the shortcomings of typical PCR and qRT-PCR assays. We selected Stilla Naica System (Stilla Technologies), Droplet Digital PCR Technology (Bio-Rad), and Lab on an Array Digital Real-Time PCR analyzer system (OPTOLANE) for comparative analysis among the various droplet digital PCR platforms currently in use commercially. Our previous study discovered a molecular marker that can distinguish Hanwoo species (Korean native cattle) using Hanwoo-specific genomic structural variation. Here, we report the pros and cons of the operation of each dPCR platform from various perspectives using this species identification marker. In conclusion, we hope that this study will help researchers to select suitable dPCR platforms according to their purpose and resources.

• International journal of advanced smart convergence
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• v.12 no.4
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• pp.306-313
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• 2023

Having pet is one of the activities people living in modern society do to relieve stress and find peace of mind. Currently, the object of companion animals has moved beyond being a real 'living entity' and has developed to a stage where the animal's upbringing process can be enjoyed in a virtual space by being programmed in digital content. This paper studies detailed elements such as character design, interaction, and realism of 'Tamagotchi (1996)', which can be said to be the beginning of digital training content, and 'Peridot (2023)', a recently introduced augmented reality-based training content. The point was that it was training content using portable electronic devices. However, while the environment in the electronic device in which Tamagotchi's character exists was a simple black and white screen, the environment in which Peridot's character operates has been changed to the real world projected on the screen based on augmented reality. Mutual communication with characters in Tamagotchi remained a response to pressing buttons, but in Peridot, it has advanced to the point where you can pet the characters by touching the smartphone screen. In addition, through object and step recognition, it was confirmed that the sense of reality had become more realistic, with toys thrown by users on the screen bouncing off real objects. We hope that this research material will serve as a useful reference for the development of digital training content to be developed in the near future.