• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.292-295
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• 2003

블루투스 전송 기술은 2.4㎓ 의 ISM(Industrial Scientific Medicine)밴드에서 주파수 호핑 방식을 사용한다. 주파수 호핑율은 연결 상태에서 초당 1600회, 조회 또는 호출 상태에서 초당 3200회의 호핑을 한다. Hop 채널 선택은 블루투스 표준안에서 제시한 5개의 호핑 시퀸스 중 하나를 선택하고 호핑 주파수에 따라 이를 매핑 함으로써 이루어진다. 본 논문에서는 6개의 상태에 따라 다르게 실행되는 채널 계산을 효율적으로 제어하고 필요한 연산모듈의 수를 줄이기 위해 9비트 프로세서를 이용해 Hop 선택 모듈을 설계하고 구현한다. 설계된 모듈은 레지스터 파일, 마이크로프로그램 제어장치, 가산, 치환(permutation), Modulo 계산을 위한 3개의 연산장치로 구성된다. Hop 채널 계산 중 가장 클럭 소요가 큰 Modulo 연산은 SRT나눗셈 알고리즘을 사용하여 음수 값 계산 및 연산 속도 향상을 꾀하였다. 제시된 Hop 선택 모듈은 하드웨어 묘사언어인 VHDL로 설계하고 시뮬레이션 및 테스트는 Xilinx FPGA를 이용해 검증하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.2
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• pp.141-146
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• 2016

This paper presents a method to improve time interval error for asynchronous communication systems. The proposed method is designed and simulated with multi-phase VCO, interpolator, phase selector, up-down counter, comparator and adder. The simulation results for CAN communication system show that the maximum time interval error can be tightly managed for satisfying the required specification. The proposed frequency modulation method can be properly used for asynchronous communication systems requiring high reliability.

• Journal of Information Processing Systems
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• v.18 no.3
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• pp.411-427
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• 2022

Digging historical and cultural information from seals in ancient books is of great significance. However, ancient Chinese seal samples are scarce and carving methods are diverse, and traditional digital image processing methods based on greyscale have difficulty achieving superior segmentation and recognition performance. Recently, some deep learning algorithms have been proposed to address this problem; however, current neural networks are difficult to train owing to the lack of datasets. To solve the afore-mentioned problems, we proposed an SEL-RefineMask which combines selector of feature pyramid network (SEL-FPN) with RefineMask to segment and recognize seals. We designed an SEL-FPN to intelligently select a specific layer which represents different scales in the FPN and reduces the number of anchor frames. We performed experiments on some instance segmentation networks as the baseline method, and the top-1 segmentation result of 64.93% is 5.73% higher than that of humans. The top-1 result of the SEL-RefineMask network reached 67.96% which surpassed the baseline results. After segmentation, a vision transformer was used to recognize the segmentation output, and the accuracy reached 91%. Furthermore, a dataset of seals in ancient Chinese books (SACB) for segmentation and small seal font (SSF) for recognition were established which are publicly available on the website.

• Analytical Science and Technology
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• v.36 no.4
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• pp.143-151
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• 2023

Considering the greater role of α-amino acids in our daily lives, the enantiomer resolution of seven α-amino acids derivatized with fluorogenic reagent (4-fluoro-7-nitro-2,1,3-benzoxadiazole, NBD-F) by chiral HPLC on amylose or cellulose trisphenylcarbamate derived chiral stationary phases (CSPs) under simultaneous ultraviolet (UV) and fluorescence (FL) detection was performed. The degree of enantioseparation and resolution was affected by nature and selector backbones of the CSPs as well as the kind of amino acids. Baseline enantiomer separation and resolutions were observed for the enantiomers of all analytes as NBD derivatives especially on coated type amylose tris(3,5-dimethylphenylcarbamate) derived CSPs (Chiralpak AD-H and Lux Amylose-1). The other CSPs also showed good enantioselectivity except for the CSPs (Chiralpak IB, Chiralcel OD-H and Lux Cellulose-1) having cellulose tris(3,5-dimethylphenylcarbamate) as chiral selectors. The developed analytical chiral method was applied to determine the enantiomeric purity of seven commercially available L-α-amino acids and the impurities as D-forms were found to be in the range 0.08-0.87 %, respectively. The intra- and interday accuracy and precision assays showed high accuracy and precision of the developed analytical method. This chiral HPLC method for the enantiomer resolution of amino acids using fluorescent derivatization could be useful for the determination of enantiomeric purity of pharmaceuticals and biological study for amino acid type compounds among chiral drugs.

• International Journal of Computer Science & Network Security
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• v.23 no.8
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• pp.63-76
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• 2023

Identity and access management in cloud computing is one of the leading significant issues that require various security countermeasures to preserve user privacy. An authentication mechanism is a leading solution to authenticate and verify the identities of cloud users while accessing cloud applications. Building a secured and flexible authentication mechanism in a cloud computing platform is challenging. Authentication techniques can be combined with other security techniques such as intrusion detection systems to maintain a verifiable layer of security. In this paper, we provide an interactive, flexible, and reliable multi-factor authentication mechanisms that are primarily based on a proposed Authentication Method Selector (AMS) technique. The basic idea of AMS is to rely on the user's previous authentication information and user behavior which can be embedded with additional authentication methods according to the organization's requirements. In AMS, the administrator has the ability to add the appropriate authentication method based on the requirements of the organization. Based on these requirements, the administrator will activate and initialize the authentication method that has been added to the authentication pool. An intrusion detection component has been added to apply the users' location and users' default web browser feature. The AMS and intrusion detection components provide a security enhancement to increase the accuracy and efficiency of cloud user identity verification.

• International journal of advanced smart convergence
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• v.12 no.1
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• pp.41-52
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• 2023

The purpose of this study is to review the proposed solutions to the Blockchain trilemma put forward by various research scholars and to draw conclusions by comparing the findings of each study. We found that the models so far developed either compromise scalability, decentralization, or security. The first model compromises decentralization. By partially centralizing the network, transaction processing speed can be improved, but security strength is weakened. Examples of this include Algorand and EOS. Because Algorand randomly selects the node that decides the consensus, the security of Algorand is better than EOS, wherein a designated selector decides. The second model recognizes that scalability causes a delay in speed when transactions are included in a block, reducing the system's efficiency. Compromising scalability makes it possible to increase decentralization. Representative examples include Bitcoin and Ethereum. Bitcoin is more vital than Ethereum in terms of security, but in terms of scalability, Ethereum is superior to Bitcoin. In the third model, information is stored and managed through various procedures at the expense of security. The application case is to weaken security by applying a layer 1 or 2 solution that stores and reroutes information. The expected effect of this study is to provide a new perspective on the trilemma debate and to stimulate interest in continued research into the problem.

• Analytical Science and Technology
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• v.22 no.2
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• pp.148-151
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• 2009

Enantiomer separation of N-fluorenylmethoxycarbonyl (FMOC) $\alpha$-amino acid was performed on covalently immobilized chiral column (Chiralpak IB) based on polysaccharide derivative as a chiral selector by reversed phase liquid chromatography. The effect of the reversed mobile phase on the chromatographic parameters of the enantioselectivities, resolution factors and retention times using covalently immobilized Chiralpak IB was shown. Also the enantiomer separation of N-FMOC $\alpha$-amino acid in the reversed and normal phase was compared and the results obtained in the former mobile phase were generally lower than those in the latter mobile phase.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1477-1480
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• 2008

주민번호대체수단은 주민번호를 대체하기 위한 본인확인정보로서, 5 개의 민간기업이 운영하는 민간 i-PIN과 행정안전부가 운영하는 공공 i-PIN이 서비스를 제공하고 있다. 하지만 주민번호대체수단이 더욱 활성화되기 위해서는 기존에 제시된 보안성, 편의성 문제를 해결해야 한다. 본 논문은 신원 선택기를 추가하여, i-PIN의 프로토콜을 변경하지 않는 범위 이내에서 i-PIN의 단점으로 지적되는 로그인 번거로움, i-PIN 사이트 기억 문제, 피싱을 비롯한 보안 문제를 해결하는 방안을 제시하였다. 제안하는 방법은 사용자가 가입한 i-PIN 제공자에 접근하는 단계, i-PIN 제공자에 id 와 비밀번호를 입력하는 단계를 없애고, 신원 선택기를 통해 사용할 신원 정보를 선택하는 것만으로 처리되도록 하였다. 본 기술은 ETRI 에서 개발중인 전자 ID 지갑 솔루션을 통해 구현되었으며, 해당 서비스는 2009 년 중에 민간 i-PIN 제공자를 통해 시범 도입될 예정이다.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.6
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• pp.769-778
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• 2009

Performances and internal behaviors of the upflow hybrid anaerobic filters treating a dairy wastewater were analyzed to identify the functions and roles of the modular crossflow media and sludge bed layer and to discover their interrelationship in the filter. The media could perform independent biological and physical separation role without buildup of sludge bed, while the role of sludge bed was dependent on the function of the media. The filter packed with the crossflow media did not necessarily require the formation of sludge bed when treating a dairy wastewater. Biological contribution of the media was controlled by that of biologically active sludge bed complementing mutually each other. The gas-liquid-solid separation capability of the media was indispensible to ensure the active biological role of sludge bed, since sludge bed buildup without the media had no independently effective biological function. It was believed that the filter in itself could also function as a selector for physical gas-liquid-solid separation resulting in selectively concentrating particles with superior settleability in sludge bed. The sludge bed in the filter played a key role in the physical solids capture from influent as well as biological organics removal.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.4
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• pp.219-225
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• 2014

The New efficient Mux-based scan latch cell design and scan test of LOS/LOC modes are proposed for detection of delay faults in digital logic circuits. The proposed scan cell design can support LOS(Launch-off-Shift) and LOC(Launch-off-Capture) tests with high fault coverage and low scan power and it can alleviate the problem of the slow selector enable signal and hold signal by supporting the logic capable of switching at the operational clock speeds. Also, it efficiently controls the power dissipation of the scan cell design during scan testing. Functional operation and timing simulation waveform for proposed scan hold cell design shows improvement in at-speed test timing in both test modes.