• 한국통신학회논문지
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• 제35권11A호
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• pp.1073-1077
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• 2010

본 논문은 Reyleigh 페이딩 채널 환경에서 다이버시티 이득 4를 얻는 새로운 4차원 성상회전(constellation rotation, CR) 기법을 제안한다. 제안된 기법은 기존의 한 변의 CR을 이용한 2차원 CR 기법과 달리 연속된 두 QAM 신호들에 대하여 두 번의 CR을 수행함으로써 동작한다. 전산 실험 결과 새로운 기법은 기존의 기법에 비해 채널 부호화의 전송률과 페이딩 채널 내 erasure 확률 값이 증가할수록 더욱 큰 성능 향상을 보인다. 또한 새로운 기법은 사용되는 각도 값들을 바꾸어 기존의 기법으로 쉽게 전환 가능하며 따라서 송신 시스템 구현 측면에서 큰 장점을 갖는다.

• 한국정밀공학회지
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• 제25권12호
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• pp.132-138
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• 2008

Recently, mastering processes for high density optical disc such as Blu-ray disc rely on electron beams, which are operable in only vacuum. In the mastering process, one of the most important tasks is to design precision stages for providing precise positioning of the works with respect to the source in a high vacuum environment. In this paper, we have developed a precision rotation table usable in the electron beam mastering. The rotation table adopted air bearings for a high positioning repeatability and velocity stability. The air leakage from the air bearings has been minimized by employing the differential exhaust scheme using three steps of air drain. The design parameters such as diameters of exhaust lines, seal lengths, and pumping speeds were decided according to the optimization method using genetic algorithm. The performance on the vacuum level of the rotation table was evaluated experimentally and theoretically. The results indicate that a vacuum level of $10^{-4}$ Pa is achieved with operation of air bearings in a vacuum chamber, which is sufficient for the electron beam mastering.

• 한국인터넷방송통신학회논문지
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• 제16권5호
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• pp.1-6
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• 2016

영상 회전은 영상 처리나 영상 패턴 인식에서 중요한 전처리 방법 중 하나이다. 영상 회전은 회전 행렬의 곱으로 이루어 진다. 그러나 기존의 방법은 대량의 실수 연산과 삼각 함수 계산을 필요로 하므로 수행 시간이 오래 걸린다. 본 논문에서는 이 같은 두가지 주요 지체 연산과정을 제거한 새로운 고속 영상 회전 알고리즘을 제안한다. 제안된 알고리즘은 단지 2개의 전단 연산을 행하므로 매우 빠르다. 또한 최신 병렬 처리 기술인 CUDA를 적용한다. CUDA는 최근 널리 보급된 GPU를 이용한 대용량 병렬처리 계산 아키텍쳐이다. GPGPU는 그래픽 전용프로세서이므로 화소 단위의 병렬처리에 탁월한 성능을 보인다. 제안된 알고리즘은 기존의 회전 알고리즘과 다양한 크기의 영상에 대해 비교 실험한다. 실험 결과는 제안된 알고리즘이 기존의 방법보다 8배 이상의 매우 우수한 성능을 보인다.

• 한국산학기술학회논문지
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• 제17권1호
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• pp.693-699
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• 2016

기존 국내 외 연구를 통해 개발된 펌프 운전 시뮬레이터는 대부분 동역학적 해석을 목적으로 하거나 운전자 교육용을 목적으로 개발되어 왔다. 그런데 기존 시뮬레이터는 운전자 위주로 구성되어 있어서 로직 설계자나 시운전 참여자들이 다양한 운전조건 또는 로직을 임의로 변경하기에는 적절하지 않다. 더욱이 최근 발전소에서 사용되는 두 개 이상의 복수펌프 운전에 대해 설계자나 운전자가 쉽게 활용할 수 있는 시뮬레이터는 개발되어 있지 않다. 그래서 본 논문에서는 MATLAB Simulink를 사용하여 일반적인 화력발전소에 주로 사용되는 복수펌프 3대에 대한 순환운전 로직에 대해 설계자나 운전원이 쉽게 사용할 수 있도록 시뮬레이션을 할 수 있는 방법을 제안 한다. 이 제안은 MATLAB을 사용할 수 있는 사용자가 발전소 DCS(Distributed Control System) 로직에 주로 사용되는 ANSI/ISA S5.2를 Simulink를 통해 구현할 수 있도록 도움을 준다. 또한 코드에 명시된 로직을 구현하기 위해 블록에 대한 Sub-System을 만들고 이를 시뮬레이터 내에서 적용이 가능한지를 검증한다. 제안된 방법을 이용한 실무 검증 단계에서는 로직 내에서 발생한 기동신호를 구현된 펌프 모델에 적용하여 3대 펌프 순환운전 시 발생할 수 있는 모든 오류 가능성을 제안된 시뮬레이터를 사용하여 설계 단계 및 운전 전에 검증할 수 있음을 실험을 통해 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제14권3호
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• pp.435-441
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• 2004

A drum bioreactor was used for the treatment of sandy soil contaminated with three kinds of aromatic compounds (phenol, naphthalene, and phenanthrene), and its performance was evaluated in two different operation modes; intermittent and continuous rotation of drum. When the drum bioreactor was operated with one rotation per day, the microbial growth was relatively low, and most of the compounds remaining in soil, except naphthalene of 90 mg/kg dry soil, disappeared mainly due to volatilization. In contrast, when the drum was continuously rotated at 9 rpm (rotation/min), the number of microorganisms was drastically increased and nitrate was consumed for growth as a nitrogen source. Phenol and phenanthrene were removed at rates of 56.7 mg/kg dry soil/day and 3.2 mg/kg dry soil/day, respectively.

• 대한족부족관절학회지
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• 제15권1호
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• pp.22-26
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• 2011

Purpose: To report the effectiveness of adding distal fibular external rotation stress test on the traditional lateral stress Cotton test in evaluating distal tibiofibular syndesmotic injuries. Materials and Methods: We evaluated syndesmotic injuries with intraoperative stress test during treating ankle fractures from March 2009 to September 2010. External rotation of distal fibula using small elevator was added on traditional stress test in case of suspicious syndesmotic injury. We retrospectively reviewed and compared the results of each test in 44 cases for which we tried both tests. Results: In 9 cases of positive traditional lateral stress tests, positive results were obtained in all cases by additional external rotation tests. In 21 cases of negative traditional stress tests, additional stress tests results were also negative. But there were 10 cases of positive additional tests and 4 of negative additional tests in equivocal results cases by the traditional stress tests. Conclusion: Using additional external rotation stress test in case of equivocal test result by the traditional lateral stress Cotton test for evaluation of syndesmotic injury during operation for ankle fracture can be a supplemental method to clarify syndesmotic injury needs fixation.

• 한국군사과학기술학회지
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• 제12권3호
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• pp.259-265
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• 2009

In the traditional percussion locks of small arms, a firing pin is struck by a hammer rotating on a single center of rotation, which makes the percussion mechanism simple and reliable. In order to strike the firing pin by the hammer, however, the firing pin should be located within the radius of rotation of the hammer. As the distance between the striking point of the firing pin and the center of rotation of the hammer becomes longer, the radius of rotation of the hammer should also be increased, which results in the increase of the volume and weight of the small arms because the hammer needs the more space for its operation inside of the small arms. In this paper, a link type percussion lock was newly proposed in order to overcome the limitation of designing small arms when using traditional percussion locks, as mentioned above. The link type percussion lock was modeled by using multi-body dynamics software and designed to satisfy the requirements such as striking force level of the hammer exerting on the firing pin enough to detonate the percussion cap of ammunitions and the safety on the accidental drop. It was applied to the newly developed dual-barrel weapon system, in which the weight and overall length are important design factors, and verified by durability test and drop test on the ground.

• Journal of Positioning, Navigation, and Timing
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• 제7권2호
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• pp.91-103
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• 2018

Conventional inertial measurement units cannot be used in the spinning vehicle with high rotation rate due to gyro's narrow operation range. By the way, angular acceleration can be measured using the accelerometer array distributed in the vehicle. This paper derives a mechanization for the gyro-free INS in the navigation frame, and proposes a gyro-free INS algorithm based on the derived mechanization. In addition, the proposed algorithm is used to estimate angular velocity, attitude, velocity, and position of a spinning vehicle with high rotation rate. A MATLAB-based software platform is configured in order to show validation of the proposed algorithm. The reference trajectory of a spinning vehicle at 3 round per second, 30 round per second are set up, and the outputs of accelerometer are generated when triads of accelerometer are located at the origin and all the axes. Navigation results of the proposed algorithm for the generated output are presented. The results show that the proposed navigation algorithm can be applied to the spinning vehicle with high rotation rate.

• 대한임베디드공학회논문지
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• 제17권6호
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• pp.309-317
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• 2022

In this paper, we propose a machine learning-based copy-move forgery detection network with dual branches. Because the rotation or scaling operation is frequently involved in copy-move forger, the conventional convolutional neural network is not effectively applied in detecting copy-move tampering. Therefore, we divide the input into rotation-invariant and scaling-invariant features based on the wavelet coefficients. Each of the features is input to different branches having the same structure, and is fused in the combination module. Each branch comprises feature extraction, correlation, and mask decoder modules. In the proposed network, VGG16 is used for the feature extraction module. To check similarity of features generated by the feature extraction module, the conventional correlation module used. Finally, the mask decoder model is applied to develop a pixel-level localization map. We perform experiments on test dataset and compare the proposed method with state-of-the-art tampering localization methods. The results demonstrate that the proposed scheme outperforms the existing approaches.

• Clinics in Shoulder and Elbow
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• 제22권2호
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• pp.93-99
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• 2019

Background: Modified Phemister operation has been widely used for the treatment of acute acromioclavicular (AC) joint dislocation. Additionally, the use of suture anchor for coracoclavicular (CC) fixation has been reported to provide CC stability. This study was conducted to evaluate the clinical and radiological results of a modified Phemister operation with CC ligament augmentation using suture anchor for acute AC joint dislocation. Methods: Seventy-four patients underwent the modified Phemister operation with CC ligament augmentation using suture anchor for acute AC joint dislocation and were followed-up for an average of 12.3 months. The visual analogue scale (VAS), range of motion, Constant score, and Korean shoulder scoring system (KSS) were used for clinical assessment. Acromioclavicular interval (ACI), coracoclavicular distance (CCD), and acromioclavicular distance (ACD) were obtained to evaluate the radiological assessments. Results: At the last follow-up, the mean VAS Score was 1.7 points, the mean joint range of the forward flexion was $164.6^{\circ}$, external rotation at the side was $61.2^{\circ}$ and internal rotation to the posterior was a level of T12. The mean Constant score and the mean KSS was 82.7 points and 84.2 points, respectively. At the mean ACI, CCD, and ACD, significant differences were found preoperatively and at the last follow-up. When the ACI, CCD, and ACD were compared with the contralateral unaffected shoulder at the last follow-up, the affected shoulders had significantly higher values. Conclusions: The modified Phemister operation with CC ligament augmentation using suture anchor is clinically and radiologically effective at acute AC joint dislocation.