Gunhee Jang
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View article: Improved interface reliability in AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors using Al2O3/ZrO2 bilayer
Improved interface reliability in AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors using Al2O3/ZrO2 bilayer Open
AlGaN/GaN high-electron-mobility transistors (HEMTs) have emerged as key components for high-frequency and high-power applications. In particular, metal–insulator–semiconductor (MIS) HEMTs are gaining attention as a promising solution for …
View article: Reconstruction of a 3D Real-World Coordinate System and a Vascular Map from Two 2D X-Ray Pixel Images for Operation of Magnetic Medical Robots
Reconstruction of a 3D Real-World Coordinate System and a Vascular Map from Two 2D X-Ray Pixel Images for Operation of Magnetic Medical Robots Open
We propose a method to reconstruct a 3D coordinate system and a vascular map for the operation of magnetic medical robots (MMRs) controlled by a magnetic navigation system (MNS) using two 2D X-ray images and four corners of an MNS. Utilizi…
View article: Dynamic Motion of a Vane in Six Degrees of Freedom and Its Effect on Wear in a Rotary-Vane Compressor Considering Fluid Lubrication
Dynamic Motion of a Vane in Six Degrees of Freedom and Its Effect on Wear in a Rotary-Vane Compressor Considering Fluid Lubrication Open
Vanes are critical components of a rotary-vane compressor. If the vanes do not achieve sufficient contact with the inner wall of the cylinder, the compression chambers do not form completely. However, excessive contact between the vane and…
View article: Improved Interface Reliability in Algan/Gan Metal–Insulator–Semiconductor High-Electron-Mobility Transistors Using Al₂O₃/Zro₂ Bilayer
Improved Interface Reliability in Algan/Gan Metal–Insulator–Semiconductor High-Electron-Mobility Transistors Using Al₂O₃/Zro₂ Bilayer Open
View article: Enhancement of reaction rate by microbubble generator in air oxidation of ferrous hydroxide suspension for crystal seed of iron oxide pigment
Enhancement of reaction rate by microbubble generator in air oxidation of ferrous hydroxide suspension for crystal seed of iron oxide pigment Open
View article: Lubrication Analysis of a Mechanical Seal Considering the Mixed Lubricant State of Gas and Liquid During External Power Shutdown of a Reactor Cooling Pump
Lubrication Analysis of a Mechanical Seal Considering the Mixed Lubricant State of Gas and Liquid During External Power Shutdown of a Reactor Cooling Pump Open
We proposed a method to calculate the pressure, opening force, and leakage rate in a mechanical seal under the mixed lubricant state of a gas and liquid for the mechanical seal in a reactor cooling pump (RCP) during external power loss. We…
View article: Optimal Motion Control of a Capsule Endoscope in the Stomach Utilizing a Magnetic Navigation System with Dual Permanent Magnets
Optimal Motion Control of a Capsule Endoscope in the Stomach Utilizing a Magnetic Navigation System with Dual Permanent Magnets Open
We propose a method to control the motion of a capsule endoscope (CE) in the stomach utilizing either a single external permanent magnet (EPM) or dual EPMs to extend the examination of the upper gastrointestinal tract. When utilizing the c…
View article: Thermo-Fluid–Structural Coupled Analysis of a Mechanical Seal in Extended Loss of AC Power of a Reactor Coolant Pump
Thermo-Fluid–Structural Coupled Analysis of a Mechanical Seal in Extended Loss of AC Power of a Reactor Coolant Pump Open
We proposed a numerical method to investigate the thermo-fluid–structural coupled characteristics of a mechanical seal of a reactor coolant pump (RCP), especially during extended loss of AC power (ELAP) operation. We developed a finite ele…
View article: Optimization of the Boundary Conditions of a Board Level Reliability Test Board to Maximize the Fatigue Life of Ball Grid Array Solder Joints under Thermal Cycling and Random Vibration
Optimization of the Boundary Conditions of a Board Level Reliability Test Board to Maximize the Fatigue Life of Ball Grid Array Solder Joints under Thermal Cycling and Random Vibration Open
We investigated the screw hole position of a board level reliability (BLR) test board to improve the fatigue reliability of solder joints under thermal cycling and random vibration. We developed a finite element model of a BLR test board a…
View article: Numerical Simulation for Curved Collector Profile in Arched Multi - Nozzle Electrospinning
Numerical Simulation for Curved Collector Profile in Arched Multi - Nozzle Electrospinning Open
View article: Optimization algorithm to generate a robust magnetic force of the magnetic navigation system against position error of a magnetic robot
Optimization algorithm to generate a robust magnetic force of the magnetic navigation system against position error of a magnetic robot Open
We propose an optimization algorithm to generate a robust magnetic force against position error to achieve good controllability of the magnetic robot in the region of interest of a magnetic navigation system comprising electromagnets. We f…
View article: Pain Reduction and Posture Alignment Improvement in Older Adults with Chronic Low Back Pain: A Novel Approach Using Spinal Thermal Massage Bed and Calf Pneumatic Cell Compression
Pain Reduction and Posture Alignment Improvement in Older Adults with Chronic Low Back Pain: A Novel Approach Using Spinal Thermal Massage Bed and Calf Pneumatic Cell Compression Open
BACKGROUND Chronic low back pain (CLBP) significantly affects the well-being of older adults, leading to diminished quality of life and heightened stress. Existing treatments have limited effectiveness and potential side effects. This stud…
View article: Identification of the Position of a Tethered Delivery Catheter to Retrieve an Untethered Magnetic Robot in a Vascular Environment
Identification of the Position of a Tethered Delivery Catheter to Retrieve an Untethered Magnetic Robot in a Vascular Environment Open
In this paper, we propose a method of identifying the position of a tethered delivery catheter in a vascular environment, recombining an untethered magnetic robot (UMR) to the tethered delivery catheter, and safely retrieving them from the…
View article: A position control method for a robotically assisted magnetic navigation system to improve the pushability of a magnetic catheter by maximizing magnetic force
A position control method for a robotically assisted magnetic navigation system to improve the pushability of a magnetic catheter by maximizing magnetic force Open
We propose a novel position control method (PCM) for the Robotically Assisted MAgnetic Navigation (RAMAN) system to improve the pushability of the magnetic catheter (MC) by maximizing the magnetic force. We expressed the magnetic force act…
View article: Resonance control method to suppress the self and mutual inductances of a 3-phase magnetic navigation system for fast drilling motion of micro helical robots
Resonance control method to suppress the self and mutual inductances of a 3-phase magnetic navigation system for fast drilling motion of micro helical robots Open
We developed a resonance control method to generate a high-speed rotating magnetic field in a three-phase magnetic navigation system composed of three electromagnets. The proposed resonance control method calculates the amplitudes and phas…
View article: Effect of Laminar, Turbulent and Slip Conditions on the Dynamic Coefficients of a Dry Gas Seal
Effect of Laminar, Turbulent and Slip Conditions on the Dynamic Coefficients of a Dry Gas Seal Open
The dynamic coefficients of a dry gas seal affect the dynamic characteristics of rotor-seal systems. Fluid films in a dry gas seal can be laminar, turbulent or with slip conditions, according to various operating conditions and design para…
View article: Sawtooth head helical magnetic robots to improve drilling performance for robotic endovascular intervention
Sawtooth head helical magnetic robots to improve drilling performance for robotic endovascular intervention Open
Helical magnetic robots driven by an external magnetic field have been extensively studied for robotic endovascular intervention to treat occlusive vascular disease. Most previous researchers have utilized cone-shaped head helical magnetic…
View article: Effects of Laminar, Turbulent, and Slip Conditions in a Fluid Film on a Dry Gas Seal
Effects of Laminar, Turbulent, and Slip Conditions in a Fluid Film on a Dry Gas Seal Open
A dry gas seal is a mechanical seal that prevents leakage of gas from rotating machines utilizing gas as a medium. Fluid film in a dry gas seal can exhibit laminar, turbulent, and slip behavior due to operating conditions and design parame…
View article: Numerical Determination of the Frictional Coefficients of a Fluid Film Journal Bearing Considering the Elastohydrodynamic Lubrication and the Asperity Contact Force
Numerical Determination of the Frictional Coefficients of a Fluid Film Journal Bearing Considering the Elastohydrodynamic Lubrication and the Asperity Contact Force Open
This paper proposes a numerical method to investigate the frictional characteristics of a fluid film journal bearing considering the elastohydrodynamic lubrication and the asperity contact force. We solved the average Reynolds equation by …
View article: Resonance-Based Design of Wireless Magnetic Capsule for Effective Sampling of Microbiome in Gastrointestinal Tract
Resonance-Based Design of Wireless Magnetic Capsule for Effective Sampling of Microbiome in Gastrointestinal Tract Open
View article: Crawling Magnetic Robot to Perform a Biopsy in Tubular Environments by Controlling a Magnetic Field
Crawling Magnetic Robot to Perform a Biopsy in Tubular Environments by Controlling a Magnetic Field Open
We developed a crawling magnetic robot (CMR), which can stably navigate and perform biopsies remotely in tubular environments by controlling a magnetic field. The CMR is composed of a crawling part and a biopsy part. The crawling part allo…
View article: Enhanced steering ability of the distal end of a magnetic catheter by utilizing magnets with optimized magnetization direction
Enhanced steering ability of the distal end of a magnetic catheter by utilizing magnets with optimized magnetization direction Open
We developed a magnetic catheter with enhanced steering ability of the distal end by utilizing magnets with optimized magnetization directions. The proposed magnetic catheter is composed of a flexible tube and three-ring magnets that enabl…
View article: Selective separating and assembling motion control for delivery and retrieval of an untethered magnetic robot in human blood vessels
Selective separating and assembling motion control for delivery and retrieval of an untethered magnetic robot in human blood vessels Open
We developed an integrated magnetic robot (IMR) that can selectively separate and assemble tethered and untethered magnetic robots. The proposed IMR is composed of a flexible-legged untethered magnetic robot (FLUMR) and a delivery catheter…
View article: Image-based feedback control of a magnetic catheter to enhance the path-following capability of the position and orientation at its distal part
Image-based feedback control of a magnetic catheter to enhance the path-following capability of the position and orientation at its distal part Open
We have proposed a novel image-based feedback control method to enhance the path-following capability for position and orientation of a magnetic catheter at its distal part. The proposed control method uses only a navigation status of the …
View article: Development of a magnetic catheter with rotating multi-magnets to achieve unclogging motions with enhanced steering capability
Development of a magnetic catheter with rotating multi-magnets to achieve unclogging motions with enhanced steering capability Open
We developed a novel magnetic catheter structure that can selectively generate steering and unclogging motions. The proposed magnetic catheter is composed of a flexible tube and two modules with ring magnets that can axially rotate in a wa…
View article: Precise position control of a helical magnetic robot in pulsatile flow using the rotating frequency of the external magnetic field
Precise position control of a helical magnetic robot in pulsatile flow using the rotating frequency of the external magnetic field Open
We propose a position control method for a helical magnetic robot (HMR) that uses the rotating frequency of the external rotating magnetic field (ERMF) to minimize the position fluctuation of the HMR caused by pulsatile flow in human blood…
View article: Comparison of one-way and two-way coupled analyses of electromagnetic machines considering magnetic and structural interactions
Comparison of one-way and two-way coupled analyses of electromagnetic machines considering magnetic and structural interactions Open
We compared one-way and two-way coupled analyses of electromagnetic machines considering magnetic and structural interaction to identify the frequency components of magnetic excitation and to determine the structural coupling effects predi…
View article: Dynamic behavior of air–oil interface in fluid dynamic bearings with a double sealing structure in a 2.5′′ hard disk drive due to non-operating axial shock
Dynamic behavior of air–oil interface in fluid dynamic bearings with a double sealing structure in a 2.5′′ hard disk drive due to non-operating axial shock Open
View article: A crawling and drilling microrobot driven by an external oscillating or precessional magnetic field in tubular environments
A crawling and drilling microrobot driven by an external oscillating or precessional magnetic field in tubular environments Open
We propose a crawling and drilling microrobot actuated by an external precessional magnetic field (EPMF) to effectively unclog obstructed blood vessels. Conventional crawling microrobots can only generate crawling motions using an external…
View article: TuB-2-3 PREDICTION OF THE OIL INJECTION TIME OF THE FDBS IN THE HDD SPINDLE MOTOR WITH TIED SHAFT BY UTILIZING THE KIRCHHOFF'S PRESSURE LAW
TuB-2-3 PREDICTION OF THE OIL INJECTION TIME OF THE FDBS IN THE HDD SPINDLE MOTOR WITH TIED SHAFT BY UTILIZING THE KIRCHHOFF'S PRESSURE LAW Open
We propose a method to predict the oil injection time of the fluid dynamic bearings (FDBs) with tied shaft by applying the Kirchhoff's pressure law. Since the oil is injected by the capillary phenomenon, the volume flow rate can be calcula…