• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.473-478
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• 2008

WAVE is a short-to-medium range communication standard that supports both public safety and private operations in roadside-to-vehicle and vehicle-to-vehicle communication environments. The core technology of physical layer in WAVE is orthogonal frequency division multiplexing (OFDM), which is sensitive to timing synchronization error. Besides, minimizing the latency in communication link is an essential characteristic of WAVE system. In this paper, a robust, low-complexity and small-latency timing synchronization algorithm suitable for WAVE system and its efficient hardware architecture are proposed. The comparison between proposed algorithm and other algorithms in terms of computational complexity and latency has shown the advantage of the proposed algorithm. The proposed architecture does not require RAM (Random Access Memory) which can affect the pipe lining ability and high speed operation of the hardware implementation. Synchronization error rate (SER) evaluation using both Matlab and FPGA implementation shows that the proposed algorithm exhibits a good performance over the existing algorithms.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.3
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• pp.74-85
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• 2021

Global Navigation Satellite System (GNSS) receivers are intrinsically vulnerable to radio frequency jamming signals due to the fundamental property of radio navigation systems. A GNSS jamming monitoring system that is capable of jamming detection, classification and localization is essential for infrastructure for autonomous driving systems. For these 3 functionalities, a GNSS jamming monitoring network consisting of a multiple of low-cost GNSS receivers distributed in a certain area is needed, and the precise time synchronizaion between multiple independent GNSS receivers in the network is an essential element. This paper presents a precise time synchronization method based on the direct use of Time Difference of Arrival (TDOA) technique in signal domain. A block interpolation method is additionally incorporated into the method in order to maintain the precision of time synchronization even with the relatively low sampling rate of the received signals for computational efficiency. The feasibility of the proposed approach is verified in the numerical simualtions.

• Journal of Aerospace System Engineering
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• v.17 no.6
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• pp.100-107
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• 2023

Open-phase fault in a Permanent Magnet Synchronous Motor (PMSM) occurs due to disconnection of phases of motor windings or inverter switch failures. When an open-phase occurs, it leads to the generation of torque ripples and vibrations in the motor, which can have a critical impact on the safety of the vehicle (including aircraft) using a PMSM as an actuator. Therefore, rapid fault detection and classification are essential. This paper proposes a classification method for detecting open-phase faults and locating fault positions in a PMSM used in aircraft applications. The proposed approach uses an Extended Kalman Filter for fault diagnosis, and it subsequently classifies faults using a Multiple Model filter.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.547-550
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• 2008

Recently, changes in the environment of user-centric internet service such as blog, UCC and IPTV and ubiquitous computing based on web service are needed to high availability system platform. High availability system is to provide safe service continuously even if system failure occurs in clustering system at the network. And it is necessary to synchronize data for reliable service in high availability system. In this paper, I implement DRBD(Disk Replicated Block Device) which is synchronization technique for data of local disks in high availability system.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.129-137
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• 2022

Recently, the technology of aircraft drivers has been transitioning from the existing hydraulically-focused mechanical system to an all-electric one due to the high precision and ease of maintenance of electric drivers. Consequently, the failure of an aircraft's electric motor can have fatal consequences. To ensure aircraft safety, efficient and timely fault diagnosis methods are required prompting the active pursuit of research into fault diagnosis technology. This paper introduces and analyses the failure types and failure diagnosis technology trends of permanent magnet synchronous motors among electric motors.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.29 no.4
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• pp.134-141
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• 2021

As the domestic aviation industry grows, the aviation maintenance field is also growing rapidly. This change calls for more aircraft maintenance technicians, and interest in safety accidents is also increasing. Individual safety climate indicates the importance of safety in the organization. We expect that three individual factors (training effectiveness, procedure effectiveness, and work pressure) relate to safety behavior in the workplace via individual safety climate. The purpose of this research is investigating the relationship between individual factors and aircraft maintenance technician's safety behavior. Previous studies related to individual factors were examined for literature review. Based on the previous studies, research model was constructed. Hypothesis was verified by effected data from 305 samples were employed for final survey. The results show that individual factors were meaningful factors to effect perceived safety behavior, and safety knowledge & safety motivation were related to safety compliance & safety participation.

• The Journal of the Korea Contents Association
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• v.21 no.3
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• pp.463-477
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• 2021

In this study, we investigated the impact of empowering leadership on intrinsic motivation, job crafting, and job performance. The role of intrinsic motivation and job crafting in the relationship between empowering leadership and job performance was verified. Covariance structure analysis was conducted to verify the research hypothesis using questionnaire data collected from SME workers in Yangsan, Ulsan, and Gyeongju. The results were as follows. First, empowering leadership has a significant influence on intrinsic motivation, job crafting. Second, empowering leadership did not have a significant influence on job performance. Third, intrinsic motivation has a significant influence on job crafting but intrinsic motivation did not have a significant influence on job performance. Fourth, job crafting has a significant influence on job performance. Finally, intrinsic motivation plays a partial mediating role in the relationship between empowering leadership and job crafting. job crafting plays a full mediating role in the relationship between empowering leadership and job performance. The results of this study suggest that employees' intrinsic motivation and job crafting should be promoted through the leader's empowering leadership in order to improve job performance.

• Journal of the Korea Convergence Society
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• v.9 no.1
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• pp.103-109
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• 2018

This study was to measure the awareness of the patient safety culture of medical workers in various occupations working in hospitals and tried to be used as useful data. As a result of evaluating department (ward), hospital, immediate supervisor/manager, communication & procedures and frequency of accident reports, the patient safety accidents considered to be the most dangerous, technicians showed high results in the department(ward), nurses showed high results in the immediate supervisor/manager area. Radiological technologists and physical therapists recognized falls and clinical pathologists and nurses recognized before during after the test as the most dangerous patient safety accidents. To raise awareness of patient safety culture, executives and practitioners should create an atmosphere in which practitioners can prioritize patient safety, gain and manage appropriate personnel, manage cooperative systems between workers or departments.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.10a
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• pp.131-133
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• 2010

2000년부터 예부선 등록 척수가 급증하고 있으며, 예부선 대부분이 10년 이상의 노후선박으로 사고의 위험성이 크다. 전체 해양사고 건수는 점차 줄어드는 추세이나, 예부선 관련 사고는 줄어들지 않고 있으며, 2010년 상반기 해양사고 분석보고서에 의하면 예부선 사고는 전년 동기대비 84.4% (32척->59척) 증가했고 이 중 충돌사고 다수인 것으로 나타났다. 예부선 사고의 근본 원인 중 예부선 종사자(선원)의 수급 어려움과 이로 인한 종사자의 고연령 저학력 경향이 뚜렷하다. 본 발표에서는 고령 예부선 운항자의 안전운항 교육을 위해 승선환경을 고려한 다양한 콘텐츠 개발 및 활용방안에 대해 제안하고자 한다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2006.06a
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• pp.506-510
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• 2006

3G 이동통신기술중 하나인 UMTS(Universal Mobile Telecommunications System)에서는 무선 구간의 안전한 통신을 위해 UMTS-AKA(Authentication and Key Agreement) 프로토콜이 사용된다. 그러나 SN(Serving Network)과 HN(Home Network)의 통신량 소비 문제, SQN(SeQuence Number) 동기화 문제 등 여러 가지 문제점이 제기되었다. 본 논문에서는 기존 프로토콜의 문제점과 IMSI(International Mobile Subscriber Identity)의 노출로 인한 프라이버시 문제점을 해결하고, ECDH(Elliptic Curve Diffie Hellman) 기법으로 완전한 전방향 안전성을 제공하는 프로토콜을 제안한다.