• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.459-462
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• 2010

본 논문은 근육의 기능을 조절하는 신경말단에 전기적인 자극을 가하여 신경의 반응 정도를 측정하는 플랫폼 구현에 관한 연구로써, 전기 자극에 대한 신경반응이 가해지는 전류량, 가해지는 전류지속시간, 전극위치에 따른 반응을 측정하였다. 신격자극의 전극 위치는 표면말달 운동신경이면 어느 신경이든지 가능하고, 신격자극 양식에는 단순연축자극(Single Twitch Stimulation), 사연속자극(Train-of-four, TOF), 두 집단 발사자극(Double Burst Stimulation, DBS)이 있다. 임베디드 시스템기반으로 가기위한 저전력 MCU를 선정하고, 기본적인 신경자극반응 측정 센서의 민감도를 알아보기 위해 센서 인터페이스를 구성하여 반응정도를 측정해야 한다. 그리고 측정된 Data의 정확도를 높이기 위해 고성능의 AD Convertor 선정하여 플랫폼을 구현하였다. 또한 본 논문의 플랫폼은 의료기기용으로 개발되었기 때문에 시스템 이용자의 안전을 고려하여 전원회로 구성 시 전원 Isolation를 고려하여 설계하였다.

• Steel and Composite Structures
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• 제2권3호
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• pp.171-194
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• 2002

In this paper, the behaviour of axially loaded partially encased composite columns made with light welded H steel shapes is examined using ABAQUS finite element modelling. The results of the numerical simulations are compared to the response observed in previous experimental studies on that column system. The steel shape of the specimens has transverse links attached to the flanges to improve its local buckling capacity and concrete is poured between the flanges only. The test specimens included 14 stubcolumns with a square cross section ranging from 300 mm to 600 mm in depth. The transverse link spacing varied from 0.5 to 1 times the depth and the width-to-thickness ratio of the flanges ranged from 23 to 35. The numerical model accounted for nonlinear stress-strain behaviour of materials, residual stresses in the steel shape, initial local imperfections of the flanges, and allowed for large rotations in the solution. A Riks displacement controlled strategy was used to carry out the analysis. Plastic analyses on the composite models reproduced accurately the capacity of the specimens, the failure mode, the axial strain at peak load, the transverse stresses in the web, and the axial stresses in the transverse links. The influence of applying a typical construction loading sequence could also be reproduced numerically. A design equation is proposed to determine the axial capacity of this type of column.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.197-202
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• 2014

Floor Impact Noise is a structure-borne noise which is mainly caused by vibration of concrete slabs. The majority of previous studies have focused on investigating performance of absorbing sheets on the reduction of floor impact noise. But absorbing sheets do not efficiently reduce heavy-weight floor impact noise level because it cannot absorb slab vibration, which is the fundamental noise source. In this study, double-floor system was developed in order to reduce floor impact noise level in residual buildings. This floor system reduces heavy-weight impact noise level by reducing vibration response at the center of slab, which has maximum amplitude in the 1st vibration mode. In order to identify the performance of the double-floor system, experiments were planned. Primary test parameters are span of double floor, arrangement and types of absorbing sheets.

• Transactions on Electrical and Electronic Materials
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• 제8권4호
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• pp.166-169
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• 2007

In applying LCD to TV application, one of the most significant factors to be improved is image sticking on the moving picture. LCD is different from CRT in the sense that it's continuous passive device, which holds images in entire frame period, while impulse type device generate image in very short time. To reduce image sticking problem related to hold type display mode, we made an experiment to drive TN-LCD like CRT. We made articulate images by turn on-off backlight, and we realized the ratio of Back Light on-off time by counting between on time and off time for video signal input during 1 frame (16.7 ms). Conventional CCFL (cold cathode fluorescent lamp) cannot follow fast on-off speed, so we evaluated new fluorescent substances of light source to improve residual light characteristic of CCFL. We realized articulate image generation similar to CRT by CCFL blinking drive and TN-LCD overdriving. As a result, reduced image sticking phenomenon was validated by naked eye and response time measurement.

• 한국통신학회논문지
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• 제22권9호
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• pp.2005-2013
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• 1997

MCMA 적응 블라인드 등화 알고리즘은 채널 진폭 등화와 함께 뛰어난 위상 보정 능력은 가지고 있지만, 특별한 형태의 새로운 신호점을 원하는 데이터 심볼점으로 간주하므로써 완전한 등화에 도달시에도 원래의 신호점과의 불일치로 인한 오차가 불가피하며, CMA의 느린 수렴 속도를 따른다. 본 논문에서는 결정 영역을 정하여 결정 영역 밖에서는 기존의 MCMA 에서와 같이 새로운 신호점을 modulus로 하고, 결정 영역 내에서는 각각 원래의 데이터 심볼점을 modulus로 하여 동작하게 하는, 이중 모드를 가지는 적응 블라인드 등화 알고리즘을 제안한다. 제안한 알고리즘은 결정 영역내에서 새로운 신호점 대신에 원래의 데이터 심볼점을 이용하므로써 정상상태에서 보다 적은 오차를 가지며, 한편 정상상태로의 급속한 수렴 속도를 가진다. 컴퓨터 모의 실험을 통하여 제안한 알고리즘이 CMA, MCMA 및 Stop-and-Go 등과 같은 기존의 적응 블라인드 등화 알고리즘들에 비해 잔류 심볼간 간섭과 수렴 속도면에서 우수한 성능을 가짐을 확인하였다.

• Advances in concrete construction
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• 제9권3호
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• pp.313-326
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• 2020

Glass fiber-reinforced polymer (GFRP) bars have been introduced as an effective alternative for the conventional steel reinforcement in concrete structures to mitigate the costly consequences of steel corrosion. However, despite the superior performance of these composite materials in terms of corrosion, the effect of replacing steel reinforcement with GFRP on the seismic performance of concrete structures is not fully covered yet. To address some of the key parameters in the seismic behavior of GFRP-reinforced concrete (RC) structures, two full-scale beam-column joints reinforced with GFRP bars and stirrups were constructed and tested under two phases of loading, each simulating a severe ground motion. The objective was to investigate the effect of damage due to earthquakes on the service and ultimate behavior of GFRP-RC moment-resisting frames. The main parameters under investigation were geometrical configuration (interior or exterior beam-column joint) and joint shear stress. The performance of the specimens was measured in terms of lateral load-drift response, energy dissipation, mode of failure and stress distribution. Moreover, the effect of concrete damage due to earthquake loading on the performance of beam-column joints under service loading was investigated and a modified damage index was proposed to quantify the magnitude of damage in GFRP-RC beam-column joints under dynamic loading. Test results indicated that the geometrical configuration significantly affects the level of concrete damage and energy dissipation. Moreover, the level of residual damage in GFRP-RC beam-column joints after undergoing lateral displacements was related to reinforcement ratio of the main beams.

• Steel and Composite Structures
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• 제30권5호
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• pp.483-492
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• 2019

In the current study, the influence of the initial lateral (sweep) shape and the cross-sectional twist imperfection on the lateral torsional buckling (LTB) response of doubly-symmetric steel I-beams was investigated. The material imperfection (residual stress) was not considered. For this objective, standard European IPN 300 beam with different unbraced span was numerically analyzed for three imperfection cases: (i) no sweep and no twist (perfect); (ii) three different shapes of global sweep (half-sine, full-sine and full-parabola between the end supports); and (iii) the combination of three different sweeps with initial sinusoidal twist along the beam. The first comparison was done between the results of numerical analyses (FEM) and both a theoretical solution and the code lateral torsional buckling formulations (EC3 and AISC-LRFD). These results with no imperfection effects were then separately compared with three different shapes of global sweep and the presence of initial twist in these sweep shapes. Besides, the effects of the shapes of initial global sweep and the inclusion of sinusoidal twist on the critical buckling load of the beams were investigated to unveil which parameter was considerably effective on LTB response. The most compatible outcomes for the perfect beams was obtained from the AISC-LRFD formulation; however, the EC-3 formulation estimated the $P_{cr}$ load conservatively. The high difference from the EC-3 formulation was predicted to directly originate from the initial imperfection reduction factor and high safety factor in its formulation. Due to no consideration of geometric imperfection in the AISC-LFRD code solution and the theoretical formulation, the need to develop a practical imperfection reduction factor for AISC-LRFD and theoretical formulation was underlined. Initial imperfections were obtained to be more influential on the buckling load, as the unbraced length of a beam approached to the elastic limit unbraced length ($L_r$). Mode-compatible initial imperfection shapes should be taken into account in the design and analysis stages of the I-beam to properly estimate the geometric imperfection influence on the $P_{cr}$ load. Sweep and sweep-twist imperfections led to 10% and 15% decrease in the $P_{cr}$ load, respectively, thus; well-estimated sweep and twist imperfections should considered in the LTB of doubly-symmetric steel I-beams.

• Journal of Mechanical Science and Technology
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• 제20권9호
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• pp.1371-1381
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• 2006

This paper deals with the active vibration control of a simply-supported beam traversed by a moving mass using fuzzy control. Governing equations for dynamic responses of a beam under a moving mass are derived by Galerkin's mode summation method, and the effect of forces (gravity force, Coliolis force, inertia force caused by the slope of the beam, transverse inertia force of the beam) due to the moving mass on the dynamic response of a beam is discussed. For the active control of dynamic deflection and vibration of a beam under the moving mass, the controller based on fuzzy logic is used and the experiments are conducted by VCM (voice coil motor) actuator to suppress the vibration of a beam. Through the numerical and experimental studies, the following conclusions were obtained. With increasing mass ratio y at a fixed velocity of the moving mass under the critical velocity, the position of moving mass at the maximum dynamic deflection moves to the right end of the beam. With increasing velocity of the moving mass at a fixed mass ratio ${\gamma}$, the position of moving mass at the maximum dynamic deflection moves to the right end of the beam too. The numerical predictions of dynamic deflection of the beam have a good agreement with the experimental results. With the fuzzy control, more than 50% reductions of dynamic deflection and residual vibration of the tested beam under the moving mass are obtained.

• 한국위성정보통신학회논문지
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• 제7권3호
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• pp.145-148
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• 2012

최근의 TV용 TFT-LCD에서는 동화상에서의 잔상발생을 줄이는 것이 중요한 기술적 요구사항이 되었다. Single-LVDS 신호체계에서 3D를 대응하기 위한 Quad Signal Package 까지 진화하면서 보다 빠른 신호를 정해진 시간안에 처리해야 하는 문제가 발생하고 있으며, 이러한 특성을 구현하기 위해서 잔상효과가 없는 Backlight에 대한 연구가 활발히 진행되고 있다. 본 연구에서는 점멸방식의 Backlight 를 사용하여, 1Frame의 시간안에 이 동작이 가능하게 구현하는 것을 목표로 삼았으며, 광원으로는 기존의 냉음극관램프를 사용하였다. 통상 냉음극관램프는 주 발광파장대를 담당하는 녹색의 잔광시간이 길어서 위와 같은 특성을 구현하기에 어려움이 있었으나, 본 연구에서는 단잔광 특성을 가지는 녹색 및 적색 형광체를 적용한 냉음극관램프를 적용하여, 1Video Frame의 시간안에 점멸동작이 가능한 백라이트를 제작하였으며, 이를 사용하여, 동화상에서 비약적인 잔상 해결 효과를 확인할 수 있었다.

• 농업과학연구
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• 제32권2호
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• pp.215-221
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• 2005

대전광역시 유성구 노은농수산물도매시장에서 유통되는 농산물의 안전성을 확립하기 위하여 농산물에 대한 잔류농약 모니터링을 실시하기에 앞서 대전지역에서 잔류분석을 시행할 관련기관(충남대학교 농생대 농화학과, 국립농산물품질관리원 충남지원, 대전광역시 보건환경연구원, 충청남도 보건환경연구원)들간의 각각의 경험을 바탕으로 한 기기 안정도 및 회수율 협력 실험을 통하여 분석 결과의 검증 및 신뢰성을 제고하고자 실시하였다. 기기안정도 실험에서는 bifenthrin의 경우 기관별 크로마토그램상의 area 변화의 상대표준편차 범위가 0.684%(기관 D)~1.212%(기관 C), chlorpyfiphos의 경우 0.159%(기관 A)~0.405%(기관 C), diazinon의 경우 0.324%(기관 B)~0.623%(기관 C), 그리고 ethoprophos의 경우 0.274%(기관 B)~0.736%(기관 C)이었다. 정량 분석법에서는 상대 표준편차범위는 10% 정도가 되어야 만족스럽다고 보고하였는데 본 연구의 결과에서 상대 표준편차는 1.212% 이하로 매우 만족스러운 결과를 얻었다. 따라서 각 기관별 기기는 매우 안정적이었음을 알 수 있었다. 회수율 실험의 경우 참깨와 오이의 결과 회수율은 63.4-94.3%이며 이들의 상대표준편차(RSD) 또한 0.32-1.03으로 각 기관별 분석방법은 별다른 문제가 없는 것으로 판단되어지며 추후에 좀 더 많은 Data를 가지고 기관간의 상관관계를 구하여야 할 것으로 사료된다.