Jongbeom Kim
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View article: Model-Based Angular Position Sensorless Drives of Main Electric Oil Pumps for e-Axles in HEV and BEV
Model-Based Angular Position Sensorless Drives of Main Electric Oil Pumps for e-Axles in HEV and BEV Open
This paper describes an approach in improving the performance of the position sensorless control of electric oil pumps with a permanent magnet synchronous motor. Electric oil pumps are widely applied for the lubricating and cooling of e-Ax…
View article: High-Strength and High-Resilience PVA+AgNW/PDMS Co-Continuous Nanocomposite for Reusable Shock Absorbers
High-Strength and High-Resilience PVA+AgNW/PDMS Co-Continuous Nanocomposite for Reusable Shock Absorbers Open
A 3D co-continuous polymer nanocomposite with high strength and high recoverability is demonstrated. This nanocomposite used hard-core-soft-matrix design which is suitable for obtaining the optimal strength. Polyvinyl alcohol (PVA) was fre…
View article: Analysis of Platen Superheater Tube Degradation in Thermal Power Plants via Destructive/Non-Destructive Characteristic Evaluation
Analysis of Platen Superheater Tube Degradation in Thermal Power Plants via Destructive/Non-Destructive Characteristic Evaluation Open
Coal-fired power plants operating under Korea’s standard supercritical pressure operate in a high-temperature environment, with steam temperatures reaching 540 °C. A standard coal-fired power plant has a 30-year design life, and lifespan d…
View article: Wear Behavior of Commercial Copper-Based Aircraft Brake Pads Fabricated under Different SPS Conditions
Wear Behavior of Commercial Copper-Based Aircraft Brake Pads Fabricated under Different SPS Conditions Open
Understanding the wear behavior of Cu-based brake pads, which are used in high-speed railway trains and aircraft, is essential for improving their design and safety. Therefore, the wear mechanism of these pads has been studied extensively.…
View article: Analysis of pipe thickness reduction according to pH in FAC facility with In situ ultrasonic measurement real time monitoring
Analysis of pipe thickness reduction according to pH in FAC facility with In situ ultrasonic measurement real time monitoring Open
Flow accelerated corrosion (FAC) is a type of pipe corrosion in which the pipe thickness decreases depending on the fluid flow conditions. In nuclear power plants, FAC mainly occurs in the carbon steel pipes of a secondary system. However,…
View article: Measurement of Absolute Acoustic Nonlinearity Parameter Using Laser-Ultrasonic Detection
Measurement of Absolute Acoustic Nonlinearity Parameter Using Laser-Ultrasonic Detection Open
The absolute acoustic nonlinearity parameter β is defined by the displacement amplitudes of the fundamental and second-order harmonic frequency components of the ultrasonic wave propagating through the material. As β is a sensitive index f…
View article: Flow-accelerated corrosion assessment for SA106 and SA335 pipes with elbows and welds
Flow-accelerated corrosion assessment for SA106 and SA335 pipes with elbows and welds Open
A FAC (flow-accelerated corrosion) test was performed for a straight pipe composed of the SA335 Gr P22 and SA106 Gr B (SA106-SA335-SA106) types of steel with welds as a function of the flow rate in the range of 7–12 m/s at 150 °C and with …
View article: Analysis of the Influence of Surface Roughness on Measurement of Ultrasonic Nonlinearity Parameter Using Contact-Type Transducer
Analysis of the Influence of Surface Roughness on Measurement of Ultrasonic Nonlinearity Parameter Using Contact-Type Transducer Open
The ultrasonic nonlinearity parameter is used to evaluate the nonlinear elasticity of a material, which is determined from the displacement amplitude of the fundamental and second-order frequencies components in an ultrasonic wave propagat…
View article: Evaluation of quadratic nonlinearity in tensile curve from ultrasonic linear and nonlinear measurements
Evaluation of quadratic nonlinearity in tensile curve from ultrasonic linear and nonlinear measurements Open
The nonlinear ultrasonic technique has been considered as a potential nondestructive method to evaluate material degradation, in which the ultrasonic nonlinearity parameter is usually measured. However, it does not tell intuitively about t…
View article: Correlation between Ultrasonic Nonlinearity and Elastic Nonlinearity in Heat-Treated Aluminum Alloy
Correlation between Ultrasonic Nonlinearity and Elastic Nonlinearity in Heat-Treated Aluminum Alloy Open
The nonlinear ultrasonic technique is a potential nondestructive method to evaluate material degradation, in which the ultrasonic nonlinearity parameter is usually measured. The ultrasonic nonlinearity parameter is defined by the elastic n…
View article: Measurement of Absolute Displacement-Amplitude of Ultrasonic Wave Using Piezo-Electric Detection Method
Measurement of Absolute Displacement-Amplitude of Ultrasonic Wave Using Piezo-Electric Detection Method Open
음향 비선형 파라미터는 입사시킨 기본주파수 성분의 변위 진폭 크기와 재료의 비선형성에 의하여 발생된 2차 고조파 성분의 변위 진폭 크기의 비로 정의된다. 본 연구에서는, 압전소자 방식을 이용한 초음파 절대변위진폭 측정의 타당성을 확인하고자, 이 기법을 통해 초음파가 입사된 SUS316 시편의 절대변위진폭을 측정하였다. 또한 비교를 위해, 레이저를 통한 패브리패럿 방식의 간섭계를 이용하여 동일 시편에 대한 절대변위진폭을 측정하…
View article: Absolute Measurement and Relative Measurement of Ultrasonic Nonlinear Parameters
Absolute Measurement and Relative Measurement of Ultrasonic Nonlinear Parameters Open
The ultrasonic nonlinear parameter is measured from the amplitudes of the harmonic frequency components generated during the propagation of ultrasonic waves in a material. There are two definitions for this parameter: absolute and relative…
View article: Measurement Method of Absolute Ultrasonic Nonlinearity excluding System Nonlinearity of Pulser
Measurement Method of Absolute Ultrasonic Nonlinearity excluding System Nonlinearity of Pulser Open
The ultrasonic nonlinear parameter 𝛽𝛽 is used to quantify nonlinearity, which is measured from the displacement amplitudes of the fundamental and second-order harmonic frequency components. A few techniques have been designed to measure th…