• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.1104-1111
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• 2014

The digital substations are being built based on the IEC 61850 network. The cooperation and protection of power system are becoming more intelligent and reliable in the environment of digital substation. This paper proposes a novel method to prevent the malfunction caused by the Transformer Magnetizing Inrush Current(TMIC) using the IEC 61850 based data sharing between the IEDs. To protect a main transformer, the current differential protection(87T) and over-current protection(50/51) are used generally. The 87T IED applies to the second harmonic blocking method to prevent the malfunction caused by the TMIC. However, the 50/51 IED may malfunction caused by the TMIC. To solve that problem, the proposed method uses a GOOSE inter-lock signal between two IEDs. The 87T IED transmits a blocking GOOSE signal to the 50/51 IED, when the TMIC is detected. The proposed method can make a cooperation of digital substation protection system more intelligent. To verify the performance of proposed method, this paper performs the real time test using the RTDS (Real Time Digital Simulator) test-bed. Using the RTDS, the power system transients are simulated, and the TMIC is generated. The performance of proposed method is verified in real-time using that actual current signals. The reaction of simulated power system responding to the operation of IEDs can be also confirmed.

• 컴퓨터교육학회논문지
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• 제13권5호
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• pp.103-110
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• 2010

그리드/클라우드 컴퓨팅 플랫폼에 외부 기관의 컴퓨팅 자원이 잠시 참여하려면 관련된 모든 방화벽 마다 필터링 규칙을 추가하여야 한다. 따라서 인터넷 응용 플랫폼이 점차 그리드/클라우드 환경으로 진화될수록 다중 방화벽을 동적으로 한 번에 통과하기 위한 연구 필요성이 증대한다. 본 논문에서는 방화벽들마다 필터링 규칙을 추가/삭제하기와 같은 기존의 네트워킹 자물쇠 관리 방식에서 일회용 네트워킹 마스터 키를 사용자가 생성하는 방식으로 전환하는 새로운 다중 방화벽 동적 통과 메커니즘을 제시한다. 여기서 마스터 키는 시스템에서 자동 생성되었던 IP 주소, 포트 번호, 시퀀스 번호 등을 일종의 일회용 패스워드 형태로 네트워킹 상대방과 사전 교환을 통한 후 서로 로컬 방화벽들을 상대방에게 열어주는 키로 활용한다. 따라서 제안된 메커니즘은 단대단 사용자 사이의 방화벽의 종류와 숫자에 관계없이 동적으로 방화벽을 통과할 수 있게 한다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권4호
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• pp.506-517
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• 2015

This paper presents a 1.248 Gb/s - 2.918 Gb/s low-power receiver MIPI-DigRF M-PHY with a fully digital frequency detection loop. MIPI-DigRF M-PHY should be operated in a very short training time which is $0.01{\mu}s$ the for HS-G2B mode. Because of this short SYNC pattern, clock and data recovery (CDR) should have extremely fast locking time. Thus, the quarter rate CDR with a fully digital frequency detection loop is proposed to implement a fast phase tracking loop. Also, a low power CDR architecture, deserializer and voltage controlled oscillator (VCO) are proposed to meet the low power requirement of MIPI-DigRF M-PHY. This chip is fabricated using a $0.11{\mu}m$ CMOS process, and the die area is $600{\mu}m{\times}250{\mu}m$. The power consumption of the receiver is 16 mW from the supply voltage of 1.1 V. The measured lock time of the CDR is less than 20 ns. The measured rms and peak jitter are $35.24ps_{p-p}$ and $4.25ps_{rms}$ respectively for HS-G2 mode.

• 한국정보과학회논문지:소프트웨어및응용
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• 제32권12호
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• pp.1247-1259
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• 2005

본 연구는 웹카메라와 같은 저해상도의 동영상으로부터 실시간 다중 얼굴 인식 시스템을 제안한다. 동영상을 이용한 얼굴 인식 시스템은 크게 얼굴 검출 단계와 얼굴 분류 단계로 나눌 수 있다. 첫째, 얼굴 검출 단계에서는 빠르고 강인한 객체 검출 성능을 가진 AdaBoost를 이용하여 얼굴 후보 영역을 검출하였고, 검출된 얼굴 후보 영역에 대한 주성분을 수행하여 데이타의 크기기 현저히 줄어든 특징 벡터를 구한 다음에 특징 벡터에 대해 SVM 기반 이진 분류를 수행하여 얼굴 후보 영역을 검증하였다. 둘째, 얼굴 분류 단계에는 주성분 분석과 멀티 SVM을 이용하여 각 얼굴들을 분류하였다. 실험 결과 본 논문에서 제안한 방법은 저해상도에서도 높은 얼굴 검출율과 동영상에서 실시간 처리가 가능한 빠른 다중 얼굴 검출과 인식 성능을 보였다. 또한 팬-틸트 기능을 가진 웹카메라를 이용한 자동 추적형 얼굴 인식 시스템을 적용하여 얼굴 검출 성능을 향상시켰고, 얼굴 인식 시스템의 응용으로 무선 On/off 얼굴인식 도어락 시스템을 구현하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 춘계학술대회
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• pp.531-532
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• 2016

손목 터널 증후군은 수근관이라는 부분이 좁아지면서 정중신경이 눌리게 되어 통증이 발생하게 되는 질환이다. 예방을 위한 방법으로 꾸준한 손목 스트레칭이 필요로 하며, 사용자에게 맞는 생활 가이드가 제공되어야 한다. 본 연구에서는 사용자 스스로가 손목 터널 증후군의 위험성을 인지하고, 스트레칭을 할 수 있도록 손목 터널 증후군 예방 시스템(carpal tunnel syndrome prevention system, CTSPS)을 구현하였다. 애플리케이션은 사용자가 설정한 사용 시간을 바탕으로 알림 및 잠금을 수행한다. 이때 사용자는 아두이노와 관성센서를 이용하여 손목 스트레칭을 할 수 있으며, 사용 패턴을 분석하여 사용자에 맞는 정보 및 가이드를 제공할 수 있다. 데이터 통신은 무구속을 만족하는 블루투스 4.0을 사용하였다. 또한 구현된 시스템을 평가하기 위해 피실험자 4명을 대상으로 3일간 스마트폰 사용 시간 및 터치 횟수를 측정하였고, 설문조사를 수행한 결과 스마트폰의 사용 빈도가 줄었으며, 긍정적인 효과를 증명할 수 있었다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.491-500
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• 2020

The present study proposes a time domain model for the Vortex-induced Vibration (VIV) simulation of a catenary riser under the combination of the current and oscillatory flow induced by vessel motion. In this model, the hydrodynamic force of VIV comprises excitation force, hydrodynamic damping and added mass, which are taken as functions of the non-dimensional frequency and amplitude ratio. The non-dimensional frequency is related with the response frequency, natural frequency, lock-in range and the fluid velocity. The relatively oscillatory flow induced by vessel motion is taken into account in the fluid velocity. Considering that the added mass coefficient and the non-dimensional frequency can affect each other, an iterative analysis is conducted at each time step to update the added mass coefficient and the natural frequency. This model is in detail validated against the published test models. The results show that the model can reasonably reflect the effect of the added mass coefficient on the VIV, and can well predict the riser's VIV under stationary and oscillatory flow induced by vessel motion. Based on the model, this study carries out the VIV simulation of a catenary riser with harmonic vessel motion. By analyzing the bending moment near the touchdown point, it is found that under the combination of the ocean current and oscillatory flow the vessel motion may decrease the VIV response, while increase the excited frequencies. In addition, the decreasing rate of the VIV under vessel surge is larger than that under vessel heave at small vessel motion velocity, while the situation becomes opposite at large vessel motion velocity.

• 한국음향학회지
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• 제29권4호
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• pp.229-236
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• 2010

위상동기식 변조기법은 주파수 대역폭의 효율과 전송 신뢰도를 높일 수 있으나 수중 채널의 시변 다중경로에 의해 인접 심볼간 간섭이 발생되어 수중통신에 적용하는 데 어려움이 있다. 본 논문에서는 동해 연근해에서 위상동기 변조방식인 BPSK와 QPSK 신호를 전송하고, 시간에 따라 변화하는 다중경로와 위상변동에 의해 왜곡된 수신신호를 보상하기 위한 위상 추정기를 결합한 적응형 등화기를 제안한다. 해상실험을 통해 전송된 위상동기식 변조신호가 수중채널의 시변 다중경로 특성에 의해 왜곡되었음을 보였고 제안된 방법에 의해 왜곡된 신호가 보정됨을 보였다. BPSK와 QPSK 신호 전송시 300 m 거리에서 각각 0.0078, 0.0376의 비트 오류율을 보였으며, 1000 m 거리에서는 0.0146, 0.0293의 비트 오류율을 보였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1958-1961
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• 2004

Ring Laser Gyroscopes used as navigational sensors inherently experience a lock-in region, where very low rotational rates are not measurable. Most RLG manufacturers use a mechanical dither motor that applies a small oscillatory rotational motion larger than this region to resolve this problem. Any input acceleration that bends this dithering axis causes flexure error, which is a noncommutative error that can not be compensated by simply using integrated gyro sensor output. This paper introduces noncommutative error equations that define attitude errors caused by flexure errors. In this paper, flexure error is classified as sensor level error if the sensing axis coincides with the dithering axis and as system level error if the two axes do not coincide. The relationship between gyro output and the rotation vector is introduced and is used to define the coordinate transformation matrix and angular motion. Equations are derived for both sensor level and system level flexure error analysis. These equations show that RLG based INS attitude error caused by flexure is directly proportional to time, amount of input acceleration and the dynamic frequency of the vehicle.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.848-854
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• 2012

We have studied the oligomerization of a fibril-forming segment of ${\alpha}$-Synulcein using a replica exchange molecular dynamics (REMD) simulation. The simulation was performed with trimers and tetramers of a 12 amino acid residue stretch (residues 71-82) of ${\alpha}$-Synulcein. From extensive REMD simulations, we observed the spontaneous formation of both trimer and tetramer, demonstrating the self-aggregating and fibril-forming properties of the peptides. Secondary structure profile and clustering analysis illustrated that antiparallel ${\beta}$-sheet structures are major species corresponding to the global free energy minimum. As the size of the oligomer increases from a dimer to a tetramer, conformational stability is increased. We examined the evolution of simple order parameters and their free energy profiles to identify the process of aggregation. It was found that the degree of aggregation increased as time passed. Tetramer formation was slower than trimer formation and a transition in order parameters was observed, indicating the full development of tetramer conformation which is more stable than that of the trimer. The shape of free energy surface and change of order parameter distributions indicate that the oligomer formation follows a dock-and-lock process.

• 산업공학
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• 제21권4호
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• pp.394-402
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• 2008

The objective of this paper is to design segmentation algorithm for applying the breast ultrasound image to CAD(Computer Aided Diagnosis). This study is conducted after understanding limits, used algorithm and demands of CAD system by interviewing with a medical doctor and analyzing related works based on a general CAD framework that is consisted of five step-establishment of plan, analysis of needs, design, implementation and test & maintenance. Detection function of CAD is accomplished by Canny algorithm and arithmetic operations for segmentation. In addition to, long computing time is solved by extracting ROI (Region Of Interests) and applying segmentation technical methods based morphology algorithm. Overall course of study is conducted by verification of medical doctor. And validity and verification are satisfied by medical doctor's confirmation. Moreover, manual segmentation of related works, restrictions on the number of tumor and dependency of image resolution etc. was solved. This study is utilized as a support system aided doctors' subjective diagnosis even though a lot of future studies is needed for entire application of CAD system.