• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.188-192
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• 2004

A Numerical analysis method is developed in order to compute the flaw and wave field for 2-dimensional floating body in the free roll motion with 3 degrees of freedom. Navier-Stokes and continuity equations are gaverning equations in tire present study. Finite Difference method is introduced to discretize the governing equation. The free surface is traced by the interface tracking method and the grid system is fitted to boundaries including free surface and body surface, which is moving in the flow field. The numerical scheme is based on Maker and Cell method. For the sake of validation of the numerical method, the computed roll decay factors according to tire midship section shapes are compared with measured results. The numerical results are discussed in order to understand the effect of midship section shape on roll motion.

• Journal of Sensor Science and Technology
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• v.27 no.6
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• pp.362-367
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• 2018

A complementary metal oxide semiconductor (CMOS) binary image sensor is proposed for low-power and low-noise operation. The proposed binary image sensor has the advantages of reduced power consumption and fixed pattern noise (FPN). A gate/body-tied (GBT) p-channel metal-oxide-semiconductor field-effect transistor (PMOSFET)-type photodetector is used as the proposed CMOS binary image sensor. The GBT PMOSFET-type photodetector has a floating gate that amplifies the photocurrent generated by incident light. Therefore, the sensitivity of the GBT PMOSFET-type photodetector is higher than that of other photodetectors. The proposed CMOS binary image sensor consists of a pixel array with $394(H){\times}250(V)$ pixels, scanners, bias circuits, and column parallel readout circuits for binary image processing. The proposed CMOS binary image sensor was analyzed by simulation. Using the dynamic comparator, a power consumption reduction of approximately 99.7% was achieved, and this performance was verified by the simulation by comparing the results with those of a two-stage comparator. Also, it was confirmed using simulation that the FPN of the proposed CMOS binary image sensor was successfully reduced by use of the double sampling process.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.18 no.2
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• pp.69-76
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• 2022

In order to prepare for a future nuclear market, research for developing floating small modular reactor has been initiated with the aim of differentiating it from large nuclear power plants such as distributed power, heat supply to remote communities and sea water desalination. Depending on the characteristics of the small modular reactor, it is necessary to design a plate and shell heat exchanger that can be manufactured smaller than the U-tube recirculation method. In this study, 12 cases are selected by changing the diameter of the heat plate, the thickness of the device body and the size of the stiffener. Finite element analysis is performed by setting the stress classification lines for the point at which deformation is expected under external pressure conditions for these analysis cases. For the basic design of the plate and shell heat exchanger, the optimal conditions are derived by analyzing the tendency of stress change in the device body and stiffener.

• Journal of Sensor Science and Technology
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• v.23 no.5
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• pp.332-336
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• 2014

In this paper, we propose a complementary metal oxide semiconductor (CMOS) binary image sensor with a gate/body-tied (GBT) PMOSFET-type photodetector for high-speed operation. The GBT photodetector of an active pixel sensor (APS) consists of a floating gate ($n^+$-polysilicon) tied to the body (n-well) of the PMOSFET. The p-n junction photodiode that is used in a conventional APS has a good dynamic range but low photosensitivity. On the other hand, a high-gain GBT photodetector has a high level of photosensitivity but a narrow dynamic range. In addition, the pixel size of the GBT photodetector APS is less than that of the conventional photodiode APS because of its use of a PMOSFET-type photodetector, enabling increased image resolution. A CMOS binary image sensor can be designed with simple circuits, as a complex analog to digital converter (ADC) is not required for binary processing. Because of this feature, the binary image sensor has low power consumption and high speed, with the ability to switch back and forth between a binary mode and an analog mode. The proposed CMOS binary image sensor was simulated and designed using a standard CMOS $0.18{\mu}m$ process.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.4
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• pp.552-558
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• 2011

A 50 kW class rotating body type wave energy converter consisted of two floating bodies and a PTO (Power Takeoff) unit is studied. As an wave energy extractor, the body is designed to have a VLCO (Variable Liquid-Column Oscillator) having a liquid filled U-tube with air chambers. Owing to the oscillation of the liquid in the U-tube caused by the air spring effect of the air chambers, the amplitude of response of the VLCO becomes significantly amplified for a target wave period. The PTO converts the rotational moment introduced from the relative motion of the hinged bodies to an hydraulic power by means of a cylinder. A high pressure accumulator, hydraulic motor and a generator are equipped in the PTO to convert the hydraulic power to electric power. A control law for adjusting the oscillation period of the VLCO is proposed for the efficient operation of the VLCO with various wave conditions. It is found that the effect of the air spring has an important role to play in making the oscillation of the VLCO match with the ocean wave. In this way, the wave energy converter equipped with the VLCO provides the most effective mode for extracting energy from the ocean wave.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.1
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• pp.45-64
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• 1993

This paper dealt with the application of a numerical method developed by the authors using the matching method proposed in the previous paper on "The Nonlinear motions of cylinders(I)[16]", and Cauchy's theorem to the problems associated with hydrodynamic forces acting on a heaving cylinders translating in a calm water and also motions of cylinders in waves. In spectral method. body boundary condition in submerged case is satisfied exactly but one in floating case is not satisfied exactly. In the numerical code developed here, the boundary condition at the free-surface and body surface is satisfied exactly at its instaneous position. It is of interest to note that the present scheme could be applied to a free-surface-piercing body without experiencing a difficulty in the numerical convergence. The computed results are compared with other results([6], [12]).

• Journal of Sensor Science and Technology
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• v.30 no.2
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• pp.114-118
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• 2021

In this study, the sensitivity of an active pixel sensor (APS) was adjusted by employing a gate/body-tied (GBT) p-channel metal-oxide semiconductor field-effect transistor (PMOSFET)-type photodetector with a transfer gate. A GBT PMOSFET-type photodetector can amplify the photocurrent generated by light. Consequently, APSs that incorporate GBT PMOSFET-type photodetectors are more sensitive than those APSs that are based on p-n junctions. In this study, a transfer gate was added to the conventional GBT PMOSFET-type photodetector. Such a photodetector can adjust the sensitivity of the APS by controlling the amount of charge transmitted from the drain to the floating diffusion node according to the voltage of the transfer gate. The results obtained from conducted simulations and measurements corroborate that, the sensitivity of an APS, which incorporates a GBT PMOSFET-type photodetector with a built-in transfer gate, can be adjusted according to the voltage of the transfer gate. Furthermore, the chip was fabricated by employing the standard 0.35 ㎛ complementary metal-oxide semiconductor (CMOS) technology, and the variable sensitivity of the APS was thereby experimentally verified.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.78-81
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• 2011

Generally, vehicle is insulated from the earth by rubber tire which is intrinsically the insulation material. The electrical ground of vehicle was floated in the sense of electric potential over the electric power sources. First of all, the floated electrical ground of vehicle should be equipotentially connected with the (-) line of electrical equipment. Bimodal tram has the different kinds of electric system. They must be kept insulated to each other electrically. When there is some unbalanced event or connection between them, it will invoke some errors or breakdown to electrical devices including sensors and actuators. This paper has investigated the floating ground effect of bimodal tram built with composite body and shown the effect according to the unbalanced ground of vehicle and the connection between different electric systems.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.191-195
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• 2001

The applications of magnetic fluid can be normally made by 1) using changes of a property of matter caused by applied magnetic field; 2) preserving magnetic fluid at a certain position or in a magnetic fluid keeping the body in a floating condition; 3) controlling the flow of magnetic fluid by means of magnetic field. However, these are usually made by using their methods together. In this study, the natural convection flow of a magnetic fluid in annular pipes is experimentally analyzed. High temperature is kept constantly inside of a circular pipe of experimental model, on the other hand, low temperature is kept constantly outside of it. In experiments, several cases are carried out in order to clarify the fluence of direction and intensity of magnetic fields on the natural convection of magnetic fluid. Therefore magnetic fields are applied in various intensity and up and down directions by permanent magnets.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.545-548
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• 1998

Thin film SOI(Silicon-On-Insulator) devices exhibit floating body effect. In this paper, SOI NMOSFET is proposed to solve this problem. Some part of gate oxide was considered to be 30nm~80nm thicker than the other normal gate oxide and simulated with TSUPREM-4. The I-V characteristics were simulated with 2D MEDICI mesh. Since part of gate oxide has different oxide thickness in proposed device, the gate electric field strength is not the same throught the gate and consequently the reduction of current kink effect is occurred.