• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.1275-1278
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• 2010

1984년 A.Shamir에 의해 처음 소개된 ID 기반 공개키 암호시스템은 ID나 메일, 주소, 소속 등 유일하게 특정할 수 있는 것을 사용자의 공개키로 사용함으로써 송신자의 공개키에 대한 정당성 확인 과정을 필요 없게 하는 방식으로 전자서명에 적용되어 다양한 방식으로 제안되었다. 하지만 ID 기반 그룹 서명에서는 그룹 관리자만이 사용자의 서명키를 생성하기 때문에 그룹 내 사용자로 위장이 가능한 문제점을 가지고 있다. 본 논문에서는 ID기반 서명에서의 문제점인 키 위탁 문제를 해결할 수 있고, 그룹 관리자만이 부담하고 있는 그룹 구성원들의 개인 서명키 생성 및 사용자 식별 연산을 소그룹 관리자를 이용하여 연산량을 분산시킬 수 있는 그룹 서명 방식을 제안한다.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.109-110
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• 2016

본 논문에서는 현재 운행되고 있는 선형 유도전동기의 슬립주파수 고정 방식이 아닌 선형 유도전동기를 이용한 자기부상열차의 슬립주파수와 수직력 및 추진력과의 관계를 이용, 열차의 가감속시 운행패턴에 따라 운행 중 슬립주파수가 가변할 수 있는 슬립주파수 가변패턴을 형성, 선형유도전동기 자기부상시스템에서의 에너지 효율향상 가능성을 검증하였다. 슬립주파수와 수직력, 추진력과의 관계를 이용 슬립주파수 일정 실효치전류제어 알고리즘과 슬립주파수 일정 벡터제어 알고리즘을 사용하여 운전조건과 슬립주파수를 변경하며 운전조건에 따른 가장 효율적인 슬립주파수의 패턴을 형성하였다. 이 후 모의시험과 실차를 이용한 실험을 통해 알고리즘에 대한 정당성과 실제 효율의 증가를 통해 타당성을 검증하였다. 앞선 두 가지 알고리즘을 통해 열차부상에 영향을 미치지 않는 범위의 수직력을 가지는 범위내에서 슬립주파수를 가변 운전 조건에 따른 최적의 슬립주파수에 대한 정보를 기반으로 운행 중 가변하는 슬립주파수를 자동열차운전(ATO)시스템에 적용 모의실험을 통해 그 적용가능성과 효율을 검증하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.3
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• pp.211-220
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• 2003

This paper presents an implementation of direct torque control (DTC) of Reluctance Synchronous Motor (RSM) with an efficiency optimization. The equipment circuit in Reluctance Synchronous Motor which consider with iron losses is theoretically analyzed and the optimal current ration between torque current and exiting current analytically derived to drive RSM at maximum efficiency. For RSM, torque dynamics can be maintained even with controlling the flux level because a torque is directly proportional to the stator current unlike induction motor. The experimental results are presented to validate the applicability of the proposed method. The developed control system show high efficiency features with 1.0 Kw RSM having 2.57 ratio of d/q reluctance.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.4
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• pp.19-27
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• 1997

This paper has described about principle and form of proposed circuit made use of soft switching technology ZVS(Zero Voltage Switching) to reduce turn on and off loss at switching. Also, the analysis of the proposed circuit has described generally by using normalized parameter and operating characteristics have been evaluated as to switching frequency and parameters. Based on the characteristics value, a method of the circuit design is proposed. In addition, this paper proves the propriety of theoretical analysis in terms of the experimental waveforms. In the future, this proposed inverter shows that it can be practically used as power source system for induction cooker etc.

• Journal of the Korean Society for information Management
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• v.26 no.2
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• pp.27-41
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• 2009

With explosive growth in the area of the Internet and IT services, various types of digital contents are generated and circulated, for instance, as converted into digital-typed, secure electronic records or reports, which have high commercial value, e-tickets and so on. However, because those digital contents have commercial value, high-level security should be required for delivery between a consumer and a provider with non face-to-face method in online environment. As a digital contents, an e-ticket is a sort of electronic certificate to assure ticket-holder's proprietary rights of a real ticket. This paper focuses on e-ticket as a typical digital contents which has real commercial value. For secure delivery and use of digital contents in on/off environment, this paper proposes that 1) how to generate e-tickets in a remote e-ticket server, 2) how to authenticate a user and a smart card holding e-tickets for delivery in online environment, 3) how to save an e-ticket transferred through network into a smart card, 4) how to issue and authenticate e-tickets in offline, and 5) how to collect and discard outdated or used e-tickets.

• Journal of IKEEE
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• v.8 no.1 s.14
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• pp.12-21
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• 2004

Error control is one of major concerns in many electronic systems. Experience shows that most malfunctions during system operation are caused by transient faults, which often mean abnormal signal delays that may result in violations of circuit element timing constraints. This paper presents a novel CMOS-based concurrent timing error detector that makes a flip-flop to sense and then signal whether its data has been potentially corrupted or not by a setup or hold timing violation. Designed circuit performs a quiescent supply current evaluation to determine timing violation from the input changes in relation to a clock edge. If the input is too close to the clock time, the resulting switching transient current in the detection circuit exceeds a reference threshold at the instant of the clock transition and an error is flagged. The circuit is designed with a $0.25{\mu}m$ standard CMOS technology at a 2.5 V supply voltage. The validity and effectiveness are verified through the HSPICE simulation. The simulation results in this paper shows that designed circuit can be used to detect setup and hold time violations effectively in clocked circuit element.

• Journal of Advanced Navigation Technology
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• v.23 no.6
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• pp.554-560
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• 2019

Excore Nuclear Flux Monitoring System in Nuclear Power Plant monitors continuous reactor power up to maximum 200%. The monitoring method, however, has to be different depending on the reactor power level. Because the logarithmic pulse signals must be counted and processed exactly due to large uncertainty if their levels are low, on the other hand, they must be processed through statistical methodolgies if theirs are high to get exact monitoring values, in point of thermal degradation view. Therefore, we developed thermal degradation input signal selection circuit to transfer low level reactor power monitoring circuit to high level reactor power circuit at rated value in this paper. We proved their validities through testing them using real data used in nuclear power plant and analyzed their results. And, These methods will be used to measure the neutron level of excore nuclear flux monitoring system in nuclear power plant.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.3
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• pp.23-30
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• 2010

Compression techniques can be applied to large-scale fingerprint systems to store or transmit fingerprint data efficiently. In this paper, we investigate the effects of FBI WSQ fingerprint image compression on the performance of a fingerprint verification system using multiple linear regressions. We propose a maximum compression using fingerprint image quality score. Based on the experiments, we can confirm that the proposed approach can compress the fingerprint images up to 3 times more than the fixed compression ratio without significant degradation of the verification accuracy.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.4
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• pp.9-16
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• 2005

In this paper, electronic ballast using double resonant inverter for 250[W] MHD lamp is designed and implemental Electronic ballast reduce a turn-onion loss by using ZVS(Zero Voltage Switching) technic in the double resonant inverter, and when circuit have an analysis, the characteristic evaluations is described generally by using the normalized i:ぉ used numerical analysis. We conform a rightfulness of theoretical analysis by experimental waveforms, rouble resonant inverter for 250[W]) MHD lamp is operated safely.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.870-879
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• 1997

At crypto'89 meeting, D. chaum suggested an undeniable signature scheme. Undeniable signatures are verified via a protocol between the signer and verifier, so the cooperation of the signer is necessary. So far, ther have been several variants of undeniable signatures to obtain a signature scheme, which can control the abous of ordinary digital signatures. In this paper we integrate these variants into a generalized undeniable-type signature scheme. Also, it will be pointed out, that undeniable signature schemes but its first realization are vulnerable in full view of eavesdropping third party. Moreover, to solve this problem, we propose a new type of digital signature, called "result-indisting-uishable undeniable signature" and construct a practical protocol that implements it.