• 한국강구조학회 논문집
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• 제9권3호통권32호
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• pp.377-390
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• 1997

본 연구는 콘크리트충전 각형강관을 이용한 기둥-보 접합부에 있어서 시공성과 충전성을 고려하여 철근으로 보강한 콘크리트충전 각형강관 기둥-H형강보 접합부를 제시하고, 1차적으로 보의 인장플랜지와 충전 각형강관 기둥 접합부와의 인장거동을 실험적으로 관찰한 후, 내진 설계 개념을 적용하여 수평 하중을 반복적으로 가할 경우의 접합부 실험을 실시하고 제시한 접합부의 내력 및 변형 특성을 파악한다. 실험결과로부터 항복선이론을 적용하여 내력을 평가하고 접합부의 내력식을 제안하며, 향후 국내의 콘크리트충전 강관구조 규준 제정에 필요한 기초 자료를 제시하는데 그 목적이 있다.

• 한국강구조학회 논문집
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• 제10권2호통권35호
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• pp.161-175
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• 1998

본 연구는 큰크리트충전 각형강관을 이용한 기둥-보 접합부에 있어서 시공성과 충전성을 고려하여 강판으로 보강한 콘크리트충전 각형강관 기둥-H형강보 접합부를 제시하고, 1차적으로 보의 인장플랜지와 충전 각형강관 기둥 접합부와의 인장거동을 실험적으로 관찰한 후, 내진설계 개념을 적용하여 수평 하중을 반복적으로 가할 경우의 접합부 실험을 실시하고 제시한 접합부의 내력 및 변형 특성을 파악한다. 실험결과로부터 항복선 이론을 적용하여 내력을 평가하고 접합부의 내력식을 제안하며, 향후 국내의 콘크리트충전 강관구조 규준 제정에 필요한 기초 자료를 제시하는데 그 목적이 있다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.320-328
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• 2011

The down town passage segment which follows in the straight line which follows recently in high speed of the railway and rail construction is increasing. Also according to quality of life improvement of the citizens whom follows in national income increase the resident demand only becomes larger day by day about a environmental creation which is comfortable and house environmental etc. Demand of the citizens is not the problem of today yesterday about like this railway mean of transportation and with the fact that continuously will increase in future. This study is to predict and reduce railway noise from the conventional PSC-beam bridges which passes through urban areas under the government strateges of speed and weight increases of railway. The purpose of this study is to recommend a proper noise prediction method for designing pleasant roadside environments. The railway design including existing line reconstructions should minimize curved alignment to increase train speed to 180~200km/hr under the government's long-term planing such as the 4th Comprehensive National Development Plan (2000~2020), National Intermodal Transportation Plan (2000~2019) and National Railroad Network Establishment Plan (2006~2015), Since the PSC-beam bridges are mainly used for bridge structures urban areas, noise measurements were performed and analyzed to recommend the noise prediction methods for each type and speed of train respectively.

• Steel and Composite Structures
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• 제23권5호
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• pp.557-570
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• 2017

In this study, the seismic performance levels of four bridges are determined using finite element modeling based on ambient vibration testing. The study includes finite element modeling, analytical modal analyses, ambient vibration testing and earthquake analyses of the bridges. For the purpose, four prestressed precast I beam bridges that were constructed for the Ankara-Sivas high speed railway line are selected for analytical and experimental studies. In the study, firstly a literature review related to the dynamic behavior of bridges especially precast beam bridges is given and then the formulation part related to ambient vibration testing and structural performance according to Turkish Seismic Code (2007) is presented. Next, 3D finite element models of the bridge are described and modeled using LARSA 4D software, and analytical dynamic characteristics are obtained. Then ambient vibration testing conducted on the bridges under natural excitations and experimental natural frequencies are estimated. Lastly, time history analyses of the bridges under the 1999 Kocaeli, 1992 Erzincan, and 1999 Duzce Earthquakes are performed and seismic performance levels according to TSC2007 are determined. The results show that the damage on the bridges is all under the minimum damage limit which is in the minimum damage region under all three earthquakes.

• 한국소음진동공학회논문집
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• 제16권11호
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• pp.1172-1178
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• 2006

Measurement of blade strain with sensors directly installed on the blade has one critical issue, how to send the sensor signal to the ground. Strain-gauges have been dominantly used to directly measure stress of a blade and either a slip ring or a telemetry system has to be used to send measured signal to the ground. However, both systems have many inherent problems and sometimes very severe limitations to be practically used. In this paper, new on-line strain monitoring method using. FBG(Fiber Bragg Grating) sensors and a beam coupler is introduced. Measurement of rotor stress using FBG sensors is nothing new, but unlike other system which installs all necessary instruments on the rotor and use telemetry system to send data to the ground, this system makes use of light's unique characteristic - light travels through space. In this new approach, single optical fiber with many FBG sensors is installed on the blade and all other necessary instruments can be installed at ground thereby giving tremendous advantages over slip ring or telemetry system. A reference sensor is also introduced to compensate the beam coupler's transmission loss change due to rotation. The suggested system's good performance is demonstrated with experiments.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권7호
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• pp.313-318
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• 2006

An automatic sample centering system is underway at the protein crystallography beam line of the Pohang Light Source to improve the efficiency of the crystal screening process. A sample pin which contains a protein crystal is mounted on a goniometer head. Then the crystal should be moved to the center of X-ray beam by controlling the motorized goniometer to obtain diffraction data. Since the X-ray beam is located at the center of the image obtained from the CCD camera when the image of the sample pin is in focus, an auto-focusing algorithm is a very important part in the auto-sample-centering system. However the results of applying several well-known auto focusing algorithms directly to the images are not satisfactory owing to the following factors: misalignment of CCD camera, non-uniform cryo-stream in the background of the image and the supporter of the loop. The performance of an auto-focusing algorithm can be increased if the algorithm is applied to only the loop region identified. Non-uniform cryo-stream and a various illumination condition and a stain, which is shown in the image, are main obstacles to loop region identification. In this paper, a simple loop region identification algorithm, which can solve these problems, is proposed and the effective ness of the proposed scheme is shown by applying the auto-focusing algorithm to the loop region identified.

• 한국강구조학회 논문집
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• 제10권2호통권35호
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• pp.291-301
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• 1998

종리브로 보강된 충전형 원형강관에 H형강보를 사용한 접합부 모델실험 결과와 항복선이론 및 수치해석을 이용하여 접합부 국부내력의 추정을 위한 기초 자료를 제시하고 궁극적으로는 원형강관 접합부의 보강법을 연구하여 다이아프램이 없는 콘크리트 충전강관 기둥-H형강보 접합부의 개발을 위한 기초자료를 제시하고자 한다.

• 한국레이저가공학회지
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• 제4권2호
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• pp.21-28
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• 2001

The laser strengthening of 35kgf/㎟ and 60kgf/㎟ grade steel sheets is investigated by using CO$_2$ laser beam irradiation. The increase of tensile strength is dominated by the number of fully penetrated melting line. Also. the optimal laser input energy(hardness) and the number of melting line (melting width) are important variables for laser strengthening. Local strengthening by laser beam may be effective for the weight reduction of components where the tailored welded blank can not be applied.

• Current Optics and Photonics
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• 제5권5호
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• pp.500-505
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• 2021

We demonstrated a wide-fan-angle flat-top irradiance pattern with a very narrow linewidth by using an aspheric lens and a long-pitch reflective diffraction grating. First, we numerically designed a diffraction-based linear beam homogenizer. The structure of the Al diffraction grating with an isosceles triangular shape was optimized with 0.1-mm pitch, 35.5° slope angle, and 0.02-mm radius of the rounding top. According to the numerical results, the linear uniformity of the irradiance was more sensitive to the working distance than to the shape of the Al grating. The designed Al grating reflector was fabricated by using a conventional mold injection and an Al coating process. A uniform linear irradiance of 405-nm laser diode with a 100-mm flat-top length and 0.176-mm linewidth was experimentally demonstrated at 140-mm working distance. We believe that our proposed linear beam homogenizer can be used in various potential applications at a precise inspection system such as three-dimensional morphology scanner with line lasers.

• 한국인터넷방송통신학회논문지
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• 제24권2호
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• pp.155-160
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• 2024

편광 선택적 빔 분리 격자는 수많은 광학 정보처리 시스템에서 널리 사용되고 있다. 본 논문에서는 고효율 플라즈마 편광 빔 분리기 (PBS)를 설계하기 위하여 Littrow 구조에서 Ag 금속 층으로 구성된 소자를 구현하였다. 구현한 PBS는 투과되는 0차 TE 편광과 반사되는 0차 TM 편광에서 높은 회절효율을 달성할 수 있도록 격자깊이 및 격자 비율을 정확한 모드 전송선로 이론 (Modal Transmission-Line Theory)을 사용하여 최적화하였다. 최적화된 결과로부터 PBS는 입사 파장과 각도에 대한 광대역 특성의 장점을 가지고 있으며, TE, TM 편광 모두에 대하여 95% 보다 높은 효율을 나타내었다. 그러므로, 높은 흡광비를 갖는 이 고효율 PBS 광대역 격자는 우수한 광 회절 장치로 사용될 수 있다.