• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.3 s.345
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• pp.32-38
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• 2006

In this paper, an intercell interference (ICI) reduction technique is proposed for OFDM-based cellular systems using the concept of virtual multiple antenna where multiple antenna techniques are performed on a set of subcarriers, not on the actual antenna array. The proposed technique is especially effective for user terminals with a single antenna at cell boundary in fully-loaded OFDM cellular systems with a frequency reuse factor equal to 1. Proposed ICI reduction techniques developed for SISO and MISO environments are shown to be robust to symbol timing offsets and efficient for various cell environments by adjusting group size depending on the number of adjacent cells. Also, the concept of a virtual signature randomizer (VSR) is introduced to improve channel separability in the virtual MIMO approach. It is shown by simulation that the proposed techniques are effective in reducing ICI and inter-sector interference compared with the conventional methods.

• Journal of Nutrition and Health
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• v.36 no.3
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• pp.319-326
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• 2003

The purposes of this study were to : (a) analyze the menus of food service operations using the menu analysis techniques of Kasavana & Smith, Miller, Merricks & Jones, Pavesic and Uman, (b) closely examine the characteristics of the five analysis techniques. Calculations for the menu analysis were done by computer using the MS 2000 Excel spreadsheet program. Menu mix% and unit contribution margin were used as variables by Kasavana & Smith, sales volume and food cost% by Miller, sales volume and cash contribution by Merrick & Jones, weighted contribution margin and food cost% by Pavesic, and total cash contribution and unit contribution margin by Uman. In each case, a four-cell matrix was created, and menu items were located in each according they achieved high or low scores with respect to two variables. Items that scored favorably on both variables were rated in the top category (e.g., star, prime, signature, group A, winner) and those that scored below average on both were rated in the lowest category (e.g., dog, problem, loser, group D, loser). While the 3 methods of Kasavana & Smith, Miller, Merrick & Jones focus on customers' viewpoints, the others consider the managers' viewpoints. Therefore, it is more likely to be desirable for decision-making on menus if the menu analysis technique chosen is suited to its purpose.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.765-772
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• 2004

Multicast communication is simultaneous transmission of data to multiple receivers and saves considerably sender resources and network bandwidth. It has high risk to attack using group address and inherent complexity of routing packets to a large group of receivers. It is therefore critical to provide source authentication, allowing a receiver to ensure that received data is authentic. In this paper, we propose the multiple chain authentication scheme for secure and efficient multicast stream. To evaluate the performance of our scheme, we compare our technique with two other previously proposed schemes using simulation results. Our scheme provides non-repudiation of origin, low overhead by amortizing the signature operation over multiple packets, and high packet loss resistance.

• Journal of the Korean Magnetics Society
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• v.17 no.6
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• pp.259-264
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• 2007

This paper describes the mathematical modeling method for the static magnetic field signature generated by a magnetic scale model. we proposed the equivalent dipole modeling method utilizing a singular value decomposition technique from magnetic field signatures by magnetic sensors are located special depths below the scale model. The proposed dipole modeling method was successfully verified through comparisons with the real measured values in our non-magnetic laboratory. Using the proposed method, it is possible to predict and analyze static magnetic field distributions at any difference depths generated from the real ships as well as a scale model ship.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.623-628
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• 2001

정보화 사회로 대두되는 현대사회는 컴퓨터 확산 및 네트워크의 급속한 발전과 더불어 이를 이용한 많은 응용분야들이 연구되고 있으며, 이중 전자투표에 관한 연구 또한 활발히 진행중이다. 이는 기존의 투표 방식을 전자화할 경우 시간 및 비용 측면에서 많은 절약효과를 얻을 수 있기 때문이다. 그러나 이런 효율성에도 불구하고 전자투표를 실제 적용하는데 있어서 투표 참여 요소의 부정 및 투표권 매매와 투표자 익명성 보장 등 아직 해결해야 할 많은 문제점들이 산재해 있다. 따라서 본 논문에서는 기존 투표를 전자투표로 적용시키는 과정에서 필요한 일반적 요구사항과 부정방지 및 매매방지를 위한 특수 요구사항을 살펴볼 것이다. 특히, 투표자 익명성 보장 및 매매방지를 위해 네트워크 상에서 투표내용이 공개되더라도 사용자 익명성을 보장할 수 있는 Magic Sticker 기법을 적용함과 동시에 사용자 인증 및 메시지 인증 부분에서는 자신을 밝히지 않은 상태에서 수신자를 지정하여 자신의 신분을 증명할 수 있는 수신자 지정 그룹 서명 방식을 이용함으로서 사용자 익명성을 제공하는 안전한 전자 투표 방식을 제안한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4214-4223
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• 2012

The argument related to the use of real and anonymous names on the Internet bulletin board has recently become a main issue. When using real names, it is possible to violate free discussion and privacy. Also, when using anonymous names, it is possible to have the reverse function of the Internet in regard to the use of malicious replies or the distribution of false ideas. Therefore, this paper has made it possible to prevent the spread of the user's personal information and execute the single log-in process by using the XML-token method which is one of the SSO technologies. Also, by issuing virtual IDs and forming the path when establishing tokens, the anonymous bulletin board which provides anonymity with a conditional tracing process has been suggested. After analyzing the performance of visitor numbers at authentication time, the anonymous bulletin board based on the group signature method showed the average response rate of 0.72 seconds, 0.18 seconds, which was suggested scheme. In the authentication time 4-5 times faster response speed, respectively. Also, since the suggested system does not have to provide a single authentication process or make the user provide his or her signature, the level of user's convenience seems to be much higher. Such a result shows that the system suggested on the anonymous bulletin board has a more appropriate level of user's convenience.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.371-374
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• 2004

Induction motors are a critical component of many industrial processes and are frequently integrated in commercially available equipment. Safety, reliability, efficiency, and performance are some of the major concerns of induction motor applications. Preventive maintenance of induction motors has been a topic great interest to industry because of their wide range application of industry. Since the use of mechanical sensors, such as vibration probes, strain gauges, and accelerometers is often impractical, the motor current signature analysis (MACA) techniques have gained murk popularity as diagnostic tool. Fault tolerant control (FTC) strives to make the system stable and retain acceptable performance under the system faults. All present FTC method can be classified into two groups. The first group is based on fault detection and diagnostics (FDD). The second group is independent of FDD and includes methods such as integrity control, reliable stabilization and simultaneous stabilization. This paper presents the fundamental FDD-based FTC methods, which are capable of on-line detection and diagnose of the induction motors. Therefore, our group has developed the embedded distributed fault tolerant and fault diagnosis system for industrial motor. This paper presents its architecture. These mechanisms are based on two 32-bit DSPs and each TMS320F2407 DSP module is checking stator current, voltage, temperatures, vibration and speed of the motor. The DSPs share information from each sensor or DSP through DPRAM with hardware implemented semaphore. And it communicates the motor status through field bus (CAN, RS485). From the designed system, we get primitive sensors data for the case of normal condition and two abnormal conditions of 3 phase induction motor control system is implemented. This paper is the first step to drive multi-motors with serial communication which can satisfy the real time operation using CAN protocol.

• Journal of Information Processing Systems
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• v.17 no.4
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• pp.851-865
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• 2021

Enterprise networks in the PyeongChang Winter Olympics were hacked in February 2018. According to a domestic security company's analysis report, attackers destroyed approximately 300 hosts with the aim of interfering with the Olympics. Enterprise have no choice but to rely on digital vaccines since it is overwhelming to analyze all programs executed in the host used by ordinary users. However, traditional vaccines cannot protect the host against variant or new malware because they cannot detect intrusions without signatures for malwares. To overcome this limitation of signature-based detection, there has been much research conducted on the behavior analysis of malwares. However, since most of them rely on a sandbox where only analysis target program is running, we cannot detect malwares intruding the host where many normal programs are running. Therefore, this study proposes a method to detect malware variants in the host through logs rather than the sandbox. The proposed method extracts common behaviors from variants group and finds characteristic behaviors optimized for querying. Through experimentation on 1,584,363 logs, generated by executing 6,430 malware samples, we prove that there exist the common behaviors that variants share and we demonstrate that these behaviors can be used to detect variants.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.2
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• pp.167-177
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• 2024

This paper proposes optimization techniques for SeaSign, an isogeny-based digital signature algorithm. SeaSign combines class group actions of CSIDH with the Fiat-Shamir with abort. While CSIDH-based algorithms have regained attention due to polynomial time attacks for SIDH-based algorithms, SeaSiogn has not undergone significat optimization because of its inefficiency. In this paper, an efficient signing method for SeaSign is proposed. The proposed signing method is simple yet powerful, achived by repositioning the rejection sampling within the algorithm. Additionally, this paper presnts parameters that can provide optimal performance for the proposed algorithm. As a result, by using the original parameters of SeaSign, the proposed method is three times faster than the original SeaSign. Additonally, combining the newly suggested parameters with the signing method proposed in this paper yields a performance that is 290 times faster than the original SeaSign and 7.47 times faster than the method proposed by Decru et al.

• Journal of Digital Convergence
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• v.19 no.10
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• pp.287-293
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• 2021

Recently, public certificates issued by nationally-recognized certification bodies have been abolished, and internet companies have issued their own common certificates as certification authority. The Electronic Signature Act was amended in a way to assign responsibility to Internet companies. As the use of a joint certificate issued by Internet companies as a certification authority is allowed, it is expected that the fraud damage caused by the theft of public key certificates will increase. We propose an authentication model that can be used in a security gateway that combines PKI with a blockchain with integrity and security. and to evaluate its practicality, we evaluated the security of the authentication model using Sugeno's hierarchical fuzzy integral, an evaluation method that excludes human subjectivity and importance degree using Delphi method by expert group. The blockchain-based joint certificate is expected to be used as a base technology for services that prevent reckless issuance and misuse of public certificates, and secure security and convenience.