• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.346-351
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• 2005

The outlet feeder pipe thinning in a PHWR (Pressurized Heavy Water Reactor) is caused by high pressure steam flow inside the pipe, which is a well known degradation mechanism called FAC (Flow Assisted Corrosion). In order to monitor the degradation, the thickness of the outlet bends closed to the exit of the pressure tube should be measured and analyzed at every official overhaul. This paper develops a mobile feeder pipe inspection robot that can minimize the irradiation dose of human workers by automating the measurement process. The robot can move by itself on the feeder pipe by using an inch worm mechanism, which is constructed by two gripper bodies that can fix the robot body on the pipe, one extendable and contractable actuator, and a rotation actuator connected the two gripper bodies to move forward and backward, and to rotate in the circumferential direction

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.10
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• pp.735-741
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• 2007

An axial F.R.P. fan model for cooling tower is developed. The fan is designed using the equations for one dimensional inviscid flow through the fan blade. Fan shape is swept forward with a parabolic function. Calculations of the three dimensional turbulent flow around the fan are carried out to investigate performance of the fan. Data of the total pressure rise and hydraulic efficiency can be obtained for the various setting angles. Calculated values of the total pressure rise and hydraulic efficiency at the design point are less than those of the design specification. The prototype of the F.R.P. fan is made by laminating of the fiberglass and epoxy resins on the mold of fan shape.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.9
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• pp.1198-1206
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• 1997

The flow characteristics of an intermittent fuel injection into a stationary ambient air were investigated using gasoline. The measurements were made by two-channel, air cooling type Phase Doppler Anemometer(PDA) system (DANTEC, 750 MW). And a pintle type injector of MPI (Multi-point Port Injection) system was utilized as a fuel injector. The PDA receiver optic was set up in a 60.deg. C forward scatter arrangement to obtain the optimum scattering signal of fuel droplets. The data were obtained by synchronizing PDA system with the fuel injection period, and the axial and radial velocity and turbulent components of fuel droplets were mainly measured for the analysis of temporal and spatial distribution depending upon the fuel injection pressures.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.4
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• pp.31-38
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• 1993

Horn rudders or flap rudders with a gap between forward and after part are used for effective steering of a ship or a submerged body. It is necessary to analyze the effect of a gap since it affects the performance of rudders. In this paper, an equation to calculate the lift acting on a two-dimensional flap rudder in uniform flow is derived by using the thin hydrofoil theory and the analytic solution of viscous flow in a channel formed by two coaxial cylindrical walls to which a pressure gradient is applied.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.2
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• pp.228-239
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• 1992

The purpose of the present research is to develop an efficient numerical method for the calculation of potential flow and predict the wave-making resistance for the application to ship design of tuna purse seiner. The paper deals with the numerical calculation of potential flow around the series 60 with forward velocity by the new slender ship theory. This new slender ship theory is based on the asymptotic expression of the Kelvin-source, distributed over the small matrix at each transverse section so as to satisfy the approximate hull boundary condition due to the assumption of slender body. Some numerical results for series 60, C sub(b) =0.6, hull are presented in this paper. The wave pattern and wave resistance are computed at two Froude numbers, 0.267 and 0.304. These results are better than those of Michell's thin ship theory in comparison with measured results. However, it costs much time to compute not only wave resistance but also wave pattern over some range of Froude numbers. More improvements are strongly desired in the numerical procedure.

• Journal of the Korean Society of Visualization
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• v.13 no.1
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• pp.21-25
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• 2015

Three-dimensional vortex structures in the corner region of translating normal plates are visualized experimentally with defocusing digital particle image velocimetry. Vortex formation processes for three plates with corner angle $60^{\circ}$, $90^{\circ}$, and $120^{\circ}$ are compared in order to study the effect of corner shape on vortex formation. In all cases, the self-induction of the starting vortex and its interaction with the potential flow induced by the moving plate cause the vortex to change its form dynamically after the plate starts to translate. While the vortex near a corner follows the plate in the low corner angle of $60^{\circ}$, the vortex separates early from the plate and its forward motion becomes slow in the high corner angle of $120^{\circ}$. It is also found that the starting vortex can transport inward at the corner, which depends on the corner angle.

• Economic and Environmental Geology
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• v.17 no.3
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• pp.163-169
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• 1984

A linear inversion of heat flow values using heat production data with reliable value is studied in this work. To evaluate 2-D problem, a thin vertical sheet model is considered. Making use of a relation based on potential theory, a new relation between $q_{rad}$ and $A_0$ is derived. The forward calculations with noise and without noise are shown. The inversion of random search is comparable to that of ridge regression method. The agreements between the computed and best fit after inversion suggest the importance of random search method in the inversion technique.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.705-708
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• 1988

Ultrasound Doppler Diagnostic System utilizes the Doppler effect for measurement of blood velocity. The sign of the Doppler frequency shift represents blood flow direction. Pulsed Doppler System uses Phase detector and zerocrossing method to produce simultaneous independent audio and velocity signals for forward and reverse blood flow direction in the time domain, had been fabricated. But time-domain analyzing such as audio evaluation and zerocrossing detection for instantaneous and mean frequency measurement doesn't, provide both an accurate and quantitative result. Therefore, it is necessary to adopt frequency domain technique to improve system performance. In this paper, we describe a unit which is composed of Pulsed Doppler System and real-time spectrum analyzer (installed TMS 32010 DSP Chip). This unit shows time-dependent spectrum variation and mean velocity of blood Signal.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.709-712
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• 1988

Ultrasonic Doppler Diagnostic System utilizes the Doppler effect for measurement of blood velocity. The sign of the Doppler frequency shift represents blood flow direction. CW(Continuous-Wave) Doppler System uses quadrature detection and phase rotation method to produce simultaneous independent audio and velocity signals for forward and reverse blood flow direction in the time-domain, had been fabricated. But time-domain analyzing such as audio evaluation and zero- crossing detection for instantaneous and mean frequnecy measurement do not provide both an accurate and quantitative result. Therefore, it is necessary to adopt frequency-domain technique to improve system performance. In this paper, we describe a unit which is composed of CW Doppler System and real-time spectrum analyzer (installed TMS 32010 DSP Chip). This unit shows time-dependent spectrum variation and mean velocity of Blood signal.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.816-821
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• 2004

The outlet feeder pipe thinning in a PHWR (Pressured Heavy Water Reactor) is caused by high pressure steam flow inside the pipe, which is a well known degradation mechanism called FAC (Flow Assisted Corrosion). In order to monitor the degradation, the thickness of the outlet bends closed to the exit of the pressure tube should be measured and analyzed at every official overhaul. This paper develops an automatic feeder pipe inspection system that can minimize the irradiation dose by automating the measurement process. The robot can move by itself on the feeder pipe by using an inch worm mechanism, which is constructed by two gripper bodies that can fix their body on the pipe and one extendable and retractable body connected the two gripper bodies to move forward and backward.