• ETRI Journal
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• v.39 no.3
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• pp.373-382
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• 2017

A new internally compensated low drop-out voltage regulator based on the cascoded flipped voltage follower is presented in this paper. Adaptive biasing current and fast charging/discharging paths have been added to rapidly charge and discharge the parasitic capacitance of the pass transistor gate, thus improving the transient response. The proposed regulator was designed with standard 65-nm CMOS technology. Measurements show load and line regulations of $433.80{\mu}V/mA$ and 5.61 mV/V, respectively. Furthermore, the output voltage spikes are kept under 76 mV for 0.1 mA to 100 mA load variations and 0.9 V to 1.2 V line variations with rise and fall times of $1{\mu}s$. The total current consumption is $17.88{\mu}V/mA$ (for a 0.9 V supply voltage).

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.1 s.71
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• pp.85-92
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• 2006

This paper investigates critical loads of the tapered Beck's columns with clamped and spring supports, subjected to a subtangential follower force. The linearly tapered columns with the solid rectangular cross-section is adopted as the column taper. The differential equation governing free vibrations of such Beck's columns is derived using the Bemoulli-Euler beam theory. Both divergence and flutter critical loads are calculated from the load-frequency curves which are obtained by solving the differential equation. The critical loads are presented as functions of various non-dimensional system parameters: the taper type, the subtangential parameter and the spring stiffness.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.144-145
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• 2021

This study analyzed the cases of cracks in piles due to the use of followers under construction conditions where water exists inside the piles, and confirmed whether the piles were cracked through a field test simulating the construction conditions in which water pressure inside the piles was generated by a hammer. According to the construction case, under the construction condition where the pile length is 20% to 30% shorter than the drilled length, about 80% cracks occur, so there is a high possibility of cracking due to water inside the pile. A field test was conducted to confirm the type of pile failure due to hammer under the construction condition in which water exists inside the pile. The pile head was not destroyed by the compressive load, and one or more longitudinal cracks occurred along the PC steel wire. The closed end pile generates water pressure by hammer. the follower and cushion(compression plywood) must be drilled at least 0.4D. It is expected that improved quality control will be possible as the water pressure inside the pile is reduced.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.1-5
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• 2003

This paper deals with dynamic instability of slender rocket-propelled flying bodies, such as launch vehicle and advances missiles subjected to aerodynamic loads and an end rocket thrust. A flying body is simplified into a uniform free-free beam subjected to an end follower thrust. Two types of aerodynamic loads are assumed in the stability analysis. Firstly, it is assumed that two concentrated aerodynamic loads act on the flying body at its nose and tail. Secondly, to take account of effect of unsteady flow due to motion of a flexible flying body, aerodynamic load is estimated by the slender body approximation. Extended Hamilton's principle is applied to the considered beam for deriving the equation of motion. Application of FEM yields standardeigen-value problem. Dynamic stability of the beam is determined by the sign of the real part of the complex eigen-values. If aerodynamic loads are concentrated loads that act on the flying body at its nose and tail, the flutter thrust decreases by about 10% in comparison with the flutter thrust of free-free beam subjected only to an end follower thrust. If aerodynamic loads are distributed along the longitudinal axis of the flying body, the flutter thrust decreases by about 70% in comparison with the flutter thrust of free-free beam under an end follower thrust. It is found that the flutter thrust is reduced considerably if the aerodynamic loads are taken into account in addition to an end rocket thrust in the stability analysis of slender rocket-propelled flying bodies.

• Journal of Sensor Science and Technology
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• v.19 no.1
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• pp.25-30
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• 2010

This paper presents a low noise CMOS regulator for a low power capacitive sensor interface in a $0.5{\mu}m$ CMOS standard technology. Proposed LDO regulator circuit consist of a voltage reference block, an error amplifier and a new buffer between error amplifier and pass transistor for a good output stability. Conventional source follower buffer structure is simple, but has a narrow output swing and a low S/N ratio. In this paper, we use a 2-stage wide band OTA instead of source follower structure for a buffer. From SPICE simulation results, we got 0.8 % line regulation and 0.18 % load regulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.2
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• pp.139-143
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• 2010

Whiplash injuries often occur in motor vehicle collision accidents. This injury frequently occurs in the cervical region. However, the reason for this has not yet been clarified. In this study, a multi-body neck model with muscles was designed. Some muscles in the model were preloaded; these were previously determined using the concept of the follower load. Cervical spinal vertebrae, discs, and muscles were designed in accordance with the human cervical spine. The purpose of this study was to investigate the effect of preloads on muscles. The results imply that the whiplash model with preloaded muscles simulates practical situations more closely than models without preloads.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.9
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• pp.1385-1391
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• 1997

An analysis is presented on the stability of an elastic cantilever column subjected to a concentrated follower force as to the influence of the elastic restraint and a tip mass at the free end. The elastic restraint is formed by the rotatory springs. For this purpose, the governing equations and boundary conditions are derived by using Hamilton's principle, and the critical flutter loads and frequencies are obtained from the numerical evaluation of the eigenvalue functions of the considered system.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1243-1246
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• 2006

A new source follower circuit for the integrated circuit of AMLCDs is proposed. Active load is added and calibration operation is applied to compensate the circuits. Proposed circuit is capable of minimizing the variation from both timing and device variations through measured results, the uniformity and bias effect are discussed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.121-128
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• 1999

In this study, a numerical procedure to analyze 3-dimensional unsteady elastohydrodynamic lubrication was developed. The procedure was applied to the actual cam and roller follower of the valve mechanism for a marine diesel engine. The pressure distribution between the cam and roller follower was calculated for the several cam rotating angles. The pressure spike is shown near the roller edge and it is getting higher as the external load is increased. The roller profile for reducing the pressure spike was suggested by the Hertzian contact analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.254-257
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• 2006

In this paper a dynamic behavior(natural frequency) of a cracked cantilever and simply supported pipe conveying fluid is presented. In addition, an analysis of the flutter and buckling instability of a cracked pipe conveying fluid subjected to a follower compressive load is presented. Based on the Euler-Bernouli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations.