• Journal of Ocean Engineering and Technology
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• v.22 no.5
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• pp.100-105
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• 2008

A106 Carbon Steel has recently been used as the material for pipes, nozzles, and tank shells in nuclear power plants. Its corrosion resistance gives the steel many advantages for use in structures under high temperature and high pressure. This steel is also expected to be used as a structural material in the shipbuilding industry for applications involving severe conditions, such as high temperature and pressure. In this study, the mechanical properties of A106 carbon steel were evaluated in regard to its corrosion times. The tensile and yielding strengths decreased as the corrosion time increased. In particular, the tensile strength was influenced by corrosion. In addition, an acoustic emission (AE) technique was used to clarify the microscopic damage to specimens that had undergone corrosion for a certain period. It was found that AE parameters, such as events, energy, duration time, and amplitude were useful for evaluating the degree of damage and remaining life of the corroded specimen. Various properties of the waveform and frequency range were also seen, based on the degree of damage to the specimen from the corrosion time.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.1 s.244
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• pp.52-59
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• 2006

The vibration of hydraulic piston pumps is induced by the periodically changing cylinder chamber pressure whose waveform is significantly influenced by valve plate geometry. In this study, the force input to the housing of a bent-axis type hydraulic piston pump was computed by deriving the dynamic equations of its piston and cylinder barrel. The vibration intensity of the pump was represented by the acceleration amplitude of its housing. In order to comparatively evaluate the influence of valve plate geometry on the vibration of pump housing, two different types of valve plate were tested. The computed results showed good agreement with the experimental data, indicating that the vibration acceleration of pump housing is rather dependent on the variation amplitude of balance coefficient than the changing slope or overshoot of cylinder chamber pressure. It was also confirmed that the design effect of valve plates could be directly examined out by monitoring the vibration acceleration of pump housing.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1173-1179
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• 2011

In this paper, we propose the parser structure to realize the encoder which is standardized encoding rules to code and store the medical waveform such as an electrocardiogram or an blood pressure in aviation emergency medical service. To design the encoder based on the MDER, the effect on the scope of each tag should be considered. we design the parser with the root property which is to clarify the effect of scope between tags. the presented parser is implemented and compared with the other structures.

• International Journal of Safety
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• v.11 no.2
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• pp.10-14
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• 2012

Recently, the combined power plants are refocused rapidly as a replaceable energy system of the nuclear power plant. The large turbine is revolved highly at 1800~3600 rpm. Thus, the turbine speed should be monitored with mechanical and electrical method for a safety. The electrical cutoff valve which blocks the flow channel with the electrical signal is with a built in. The aim of this study is to develop a manufacturing technology through by the localization of a solenoid actuated directional control valve. Especially the results show performances of the solenoid valve by the experiments and modeling and the reliability estimation. Applied load port pressure was changed rapidly on the form of a quadratic curve over time. And in the cases of square waveform when 0~100 V and 20~120 V input voltage, it was driven on a stable state until 13.4 Hz and 16.6 Hz, respectively. We think that this study will give useful data for the electricity safety system of the combined power plant gas turbine.

• Journal of the Korean Magnetics Society
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• v.21 no.3
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• pp.104-107
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• 2011

We measured signals at the "Guan" region of a radially arterial pulse using the prototype of a clamping pulsimeter equipped with a Hall effect device, which is passed signals through the voltage detecting hard ware system. The important four different measuring times of the period, systolic, reflective, and notch peaks for a temporally pulse signal are obtained and compared each other from the analysis for an arbitrary pulse wave of one position of small size permanent magnet. It is possible to measure the reproducible pulse rate and blood pressure by using the cuffless clip type pulsimeter without an unpleasant oppressive feeling due to the use of pressurization.

• Progress in Superconductivity and Cryogenics
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• v.15 no.3
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• pp.35-39
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• 2013

In this paper, we present test results of developed 100 W class linear compressor for Stirling-type pulse tube refrigerator. The fabricated linear compressor has dual-opposed configuration, free piston and moving magnet type linear motor. Power transfer, efficiency and required pressure waveform are predicted with designed and measured specifications. In experiments, room temperature test with flow impedance is conducted to evaluate performance of developed linear compressor. Flow impedance is loaded to compressor with metering valve for flow resistance, inertance tube for flow inertance and buffer volumes for flow compliance. Several operating parameters such as input voltage, current, piston displacement and pressure wave are measured for various operating frequency and fixed input current level. Behaviors of dynamics and performance of linear compressor as varying flow impedance are discussed with measured experimental results. The developed linear compressor shows 124 W of input power, 86 % of motor efficiency and 60 % of compressor efficiency at its resonant operating condition.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.318-323
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• 2001

Characteristics of the pulsatile flow in a 3-dimensional elastic blood vessel are investigated to understand the blood flow phenomena in the human body arteries. In this study, a model for the elastic blood vessel is proposed. The finite volume prediction is used to analyse the pulsatile flow in the elastic blood vessel. Variations of the pressure, velocity and wall shear stress of the pulsatile flow in the elastic blood vessel are obtained. The magnitudes of the velocity waveforms in the elastic blood vessel model are larger than those in the rigid blood vessel model. The wall shear stresses on the elastic vessel vary with the blood vessel motions. Amplitude indices of the wall shear stress for blood in the elastic blood vessel are $4\sim5$ times larger than those of the Newtonian fluid. As the phase angle increased, point of the phase angle is are moved forward and the wall shear stresses are increased for blood and the Newtonian fluid.

• 한국지구물리탐사학회:학술대회논문집
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• 2009.10a
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• pp.155-159
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• 2009

Crack-controlled method which utilizes the dynamic energy such as explosives and propellent gases have been applied to the development of mineral resource and oil and civil engineering. It is necessary to consider the fracture processes associated with the material properties and external forces to control crack propagation using borehole pressure. To investigate the influence of the applied borehole pressure waveform on the crack propagation in rock masses having different material properties, a no-free surface model was used, consisting of a borehole in rock with a continuous boundary. Loading rates ranging from 1 to 100MPa/${\mu}s$ with different rock mass properties was employed to investigate the loading rate dependency of fracture patterns in the rock mass.

• Journal of Sensor Science and Technology
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• v.27 no.6
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• pp.421-426
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• 2018

To develop a piezoelectric inkjet printhead for high-resolution and high-speed printing, we studied the characteristics of an inkjet printhead by analyzing the major design parameters. An analytical model for the inkjet printhead was established, and numerical analysis of the coupled first-order differential equation for the defined state variables was performed using state equations. To design the dimension of the inkjet printhead with a driving frequency of 100 kHz, the characteristics of the flow rate and discharge pressure of the nozzle were analyzed with respect to design variables of the flow chamber, effective sound wave velocity, driving voltage, and voltage waveform. It was predicted that the change in the height of the flow chamber does not significantly affect the Helmholtz resonance frequency and discharge speed of the nozzle. From the analysis of change in flow chamber width, it is observed that as the width of the flow chamber increases, the ejection speed greatly increases and the Helmholtz resonance frequency decreases considerably, thereby substantially affecting the performance of the inkjet printhead.

• Journal of Electrical Engineering and Technology
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• v.2 no.1
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• pp.136-141
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• 2007

The Purpose Of This Paper Is To Use A Tactile Sensor To Compensate The Error Rate. Most Automated Sphygmomanometers Use The Oscillometric Method And Characteristic Ratio To Estimate Systolic And Diastolic Blood Pressure. However, Based On The Fact That Maximum Amplitude Of The Oscillometric Waveform And Characteristic Ratio Are Affected By Compliance Of The Aorta And Large Arteries, A Method To Measure The Artery Stiffness By Using A Tactile Sensor Was Chosen In Order To Integrate It With The Sphygmomanometer In The Future Instead Of Using Photoplethysmography. Since Tactile Sensors Have Very Weak Movements, Efforts Were Made To Maintain The Subject's Arm In A Fixed Position, And A 40hz Low Pass Filter Was Used To Eliminate Noise From The Power Source As Well As High Frequency Noise. An Analyzing Program Was Made To Get Time Delay Between The First And Second Peak Of The Averaged Digital Volume Pulse(${\Delta}t_{dvp}$), And The Subject's Height Was Divided By ${\Delta}t_{dvp}$ To Calculate The Stiffness Index Of The Arteries($Si_{dvp}$). Regression Equations Of Systolic And Diastolic Pressure Using $Si_{dvp}$ And Mean Arterial Pressure(Map) Were Computed From The Test Group (60 Subjects) Among A Total Of 121 Subjects(Age: $44.9{\pm}16.5$, Male: Female=40:81) And Were Tested In 61 Subjects To Compensate The Error Rate. Error Rates Considering All Subjects Were Systolic $4.62{\pm}9.39mmhg$, And Diastolic $14.40{\pm}9.62mmhg$, And Those In The Test Set Were $3.48{\pm}9.32mmhg,\;And\;14.34{\pm}9.67mmhg$ Each. Consequently, Error Rates Were Compensated Especially In Diastolic Pressure Using $Si_{dvp}$, Various Slopes From Digital Volume Pulse And Map To Systolic-$1.91{\pm}7.57mmhg$ And Diastolic $0.05{\pm}7.49mmhg$.