• JSTS:Journal of Semiconductor Technology and Science
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• 제9권3호
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• pp.160-165
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• 2009

A 12b 2 MS/s cyclic ADC processing 3.3 Vpp single-ended rail-to-rail input signals is presented. The proposed ADC demonstrates an offset voltage less than 1 mV without well-known calibration and trimming techniques although power supplies are directly employed as voltage references. The SHA-free input sampling scheme and the two-stage switched op-amp discussed in this work reduce power dissipation, while the comparators based on capacitor-divided voltage references show a matched full-scale performance between two flash sub ADCs. The prototype ADC in a $0.18{\mu}m$ 1P6M CMOS demonstrates the effective number of bits of 11.48 for a 100 kHz full-scale input at 2 MS/s. The ADC with an active die area of $0.12\;mm^2$ consumes 3.6 m W at 2 MS/s and 3.3 V (analog)/1.8 V (digital).

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.199-205
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• 2001

This paper describes the design methodology, manufacturing process, rebar tensile and bending properties. Braidtrusion is a direct Composite fabrication technique utilizing an in-line braiding and pultrusion process. The produced Composite rebar exhibits ductile stress-strain behavior similar to that of conventional steel bar. Various rebar diameters ranging from modeling scale(3m) to full-scale prototype of 9.5mm have been produced Glass Fiber Reinforced Plastics(GFRP) rebar were successfully fabricated at $\phi$8.5mm and $\phi$9.5mm nominal diameters of soild and hollow type using a braidtrusion process. Tensile and bending specimens were tested and compared with behavior of stress-strain of GFRP rebar and steel bar.

• 콘크리트학회지
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• 제7권2호
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• pp.165-174
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• 1995

정적하중은 동적하중에 비해 재하속도가 느리므로 보다 합리적인 내진설계 규준제정을 위해서는 정적 실험과 별도로 동적실험이 필요하다. 그러나 구조물의 실물크기로 동적실험을 수행하기에는 여러 가지 기계적, 경제적인 제약이 있으므로 그 크기를 축소시킨 모형실험이 일반적으로 수행되고 있다. 이 연구에서는 11개의 철근 콘크리트 보-기둥 접합부 실험체에 대해 이미 잘 알려진 상사법칙을 적용하여 길이 축척비 1 : 2 : 4로 제작하여, 재하진동수를 0.0025Hz~2.0Hz로 각각 서로 다르게 작용시켜 철근콘크리트 부재의 동적 모형실험에 대한 신뢰성을 검토하였다. 실험결과, 상사법칙에 의해 설계된 모형실험체는 원형크기 실험체의 동적거동 예측에 유용하게 사용 될 수 있음이 확인되었다.

• 한국의학물리학회지:의학물리
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• 제27권3호
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• pp.117-124
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• 2016

Intrafractional motion of patients, such as respiratory motion during radiation treatment, is an important issue in image-guided radiotherapy. The accuracy of the radiation treatment decreases as the motion range increases. We developed a control system for a robotic patient immobilization system that enables to reduce the range of tumor motion by compensating the tumor motion. Fusion technology, combining robotics and mechatronics, was developed and applied in this study. First, a small-sized prototype was established for use with an industrial miniature robot. The patient immobilization system consisted of an optical tracking system, a robotic couch, a robot controller, and a control program for managing the system components. A multi speed and position control mechanism with three degrees of freedom was designed. The parameters for operating the control system, such as the coordinate transformation parameters and calibration parameters, were measured and evaluated for a prototype device. After developing the control system using the prototype device, a feasibility test on a full-scale patient immobilization system was performed, using a large industrial robot and couch. The performances of both the prototype device and the realistic device were evaluated using a respiratory motion phantom, for several patterns of respiratory motion. For all patterns of motion, the root mean squared error of the corresponding detected motion trajectories were reduced by more than 40%. The proposed system improves the accuracy of the radiation dose delivered to the target and reduces the unwanted irradiation of normal tissue.

• Structural Engineering and Mechanics
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• 제17권3_4호
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• pp.393-408
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• 2004

There exists a clear need to monitor the performance of civil structures over their operational lives. Current commercial monitoring systems suffer from various technological and economic limitations that prevent their widespread adoption. The wires used to route measurements from system sensors to the centralized data server represent one of the greatest limitations since they are physically vulnerable and expensive from an installation and maintenance standpoint. In lieu of cables, the introduction of low-cost wireless communications is proposed. The result is the design of a prototype wireless sensing unit that can serve as the fundamental building block of wireless modular monitoring systems (WiMMS). An additional feature of the wireless sensing unit is the incorporation of computational power in the form of state-of-art microcontrollers. The prototype unit is validated with a series of laboratory and field tests. The Alamosa Canyon Bridge is employed to serve as a full-scale benchmark structure to validate the performance of the wireless sensing unit in the field. A traditional cable-based monitoring system is installed in parallel with the wireless sensing units for performance comparison.

• 한국유체기계학회 논문집
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• 제4권3호
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• pp.53-61
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• 2001

Vortex type Fluidic Device(FD) which is installed at the bottom of Safety Injection Tank(SIT) controls the discharge flow rate from the tank. In case of loss of coolant accident the injection water flows into primary system in two steps; initial high flow rate for certain period of time and subsequent low flow rate. By two-step control of the discharge flow rate, FD can ensure the effective use of water in the tank. A small-scale FD has been tested to obtain a required flow characteristics maintaining full pressure and height of prototype, which are the major contributing parameters. Through the testing of many different arrangements of internal geometry of FD, most appropriate one was selected and its performance data was obtained. As characteristics of FD, time dependent Euler number, flow rate and pressure are presented and discussed. Also a method to predict the full size FD is presented.

• 한국구조물진단유지관리공학회 논문집
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• 제23권2호
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• pp.130-134
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• 2019

본 논문에서는 레이저기반 응력측정을 위한 비접촉식 로드셀을 개발을 위하여, 실내실험을 통하여 기술을 검증하고, 실규모 실험을 통하여 문제점을 파악하였으며, 최종적으로 현장적용에 적합한 응력측정용 비접촉식 로드셀 프로토타입을 개발하였다. 이를 위하여, 중심공 압축타입의 로드셀 제작에 사용되는 로드셀 몸체 표면에 용사코팅기술을 이용하여 알루미나를 도포하고, 레이저를 기반으로한 압분광법을 이용하여, 비접촉식으로 응력을 계측하였다. 이때, 인가되는 응력과 스펙트럼 이동간의 관계가 선형임을 확인하였다. 해당 기술의 현장 적용성 확인을 위하여, 실규모 프리스트레스 콘크리트 시편을 제작하고, 레이저를 조사하여 인가된 응력을 확인하는 과정에서, 반복적인 상황 하에서 레이저 조사 위치가 동일해야 함을 확인하였다. 이를 보완하기 위하여 프로브를 고정할 수 있는 케이싱이 포함된 로드셀 프로토타입을 제작하였고, 실내일축압축시험을 통하여 압축력과 스펙트럼 이동간의 선형성을 확인하였다. 따라서, 본 연구를 통하여 개발된 비접촉식 로드셀을 이용하여, 압축력을 효과적으로 측정할 수 있을 것으로 기대된다.

• Ocean Systems Engineering
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• 제3권4호
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• pp.309-325
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• 2013

Ocean Thermal Energy Conversion (OTEC) systems utilize the temperature difference between the surface water and deep ocean water to generate electrical energy. In addition to ocean surface waves, wind and current, in certain locations like the Andaman Sea, Sulu Sea and the South China Sea the presence of strong internal waves may become a concern in floating OTEC system design. The current paper focuses on studying the dependence of the CWP hydrodynamic drag on relative velocity of the flow around the pipe, the effect of drag amplification due to vortex induced vibrations and the influence of internal waves on the floating semi and the cold water pipe integrated OTEC system. Two CWP sizes are modeled; the 4m diameter pipe represents a small scale prototype and the 10m diameter pipe represents a full commercial size CWP. are considered in the study.

• Structural Monitoring and Maintenance
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• 제1권4호
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• pp.393-409
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• 2014

Across-wind response is often the cause of significant structural vibrations that in turn cause fatigue damage to welded and other connections. The efficacy of low-cost helical strakes to mitigate such adverse response is presented for a traffic signal structure. Field observations are made on a prototype structure in a natural wind environment without and with helical strakes installed on the cantilevered arm. Through continuous monitoring, the strakes were found to be effective in reducing across-wind response at wind speeds less than 10 m/s. Estimates of fatigue life are made for four different geographical locations and wind environments. Results for the class of traffic signal structure show that helical arm strakes are most effective in locations with benign wind environments where the average annual wind speed is not more than the vortex shedding wind speed, which for this investigation is 5 m/s. It is concluded that while strakes may be effective, it is not the panacea to mitigating connection fatigue at all locations.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.987-993
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• 2003

The module UPS can flexibly implement expansion of power system capacities. Furthermore, it can be used to build up the parallel redundant system to improve the reliability of power system operation. To realize the module UPS, load sharing without interconnection among parallel connecting modules as well as a small scale and lightweight topology is necessary. In this paper, the three-arm converter/inverter is compared with the general full-bridge and half-bridge topology from a practical point of view and chosen as the module UPS topology. The switching control approaches based on a pulse width modulation of the converter and inverter of the system are presented independently The frequency and voltage droop method is applied to parallel operation control to achieve load sharing. Two prototype 3kVA modules are designed and implemented to confirm the effectiveness of the proposed approaches. Experimental results show that the three-arm UPS system has a high power factor, a low distortion of output voltage and input current, and good load sharing characteristic.