김장환 교수

In this paper a voltage modulation method based on a triangular carrier wave for the three-phase four-leg voltage source converter is described. The four-leg converter can produce three output voltages independently with one additional leg. The proposed modulation method for the four-leg converter can be implemented with a single carrier by a simple but useful "offset voltage" concept. The method is equivalent to the so called three-dimensional space vector PWM method, but its implementation is

Abstract Hardware-based cryptography that exploits physical unclonable functions is required for the secure identification and authentication of devices in the Internet of Things. However, physical unclonable functions are typically based on anticounterfeit identifiers created from randomized microscale patterns or non-predictable fluctuations of electrical response in semiconductor devices, and the validation of an encrypted signature relies on a single-purpose method such as microscopy or elec

In a three-phase four-wire utility system, three-phase unbalanced loads and many single-phase nonlinear loads result in a neutral line current that is zero-sequence current. To deal with unbalanced and nonlinear loads in a high power system, this paper suggests a multilevel four-leg pulsewidth modulation (PWM) voltage-source inverter (VSI) as a topology for the high power applications where a function is required to control the zero-sequence component as well as dq components. This paper propose

BACKGROUND: Few clinical studies have evaluated the integrity of repaired tendons and identified the timing of retears through the use of serial imaging. HYPOTHESIS: Retears after arthroscopic rotator cuff repair are uncommon in the late postoperative period (after 3 months). STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Among 221 arthroscopic rotator cuff repairs that were performed at a single hospital between May 2010 and February 2012, 61 were involved in this study. Rotator cuff

This paper proposes a new strategy to estimate the rotor flux of an induction machine. The electrical model of the induction machine presents the basic idea based on an observer structure, which is composed of a voltage model and a current model. However, the former has the defects of sensitivity to machine parameters in the low-speed range, and the latter also has defects that are sensitive to the machine parameters in wide-speed range. In spite of these shortcomings, the closed-loop flux obser

Intravesical RTX administration, in general, is a well-tolerated new therapy for DH. This patient group was refractory to all previous oral pharmacologic therapy, yet some patients responded with significant improvement in bladder capacity and continence function shortly after RTX administration. Patients at risk for autonomic dysreflexia require careful monitoring during RTX therapy.

Abstract Nanoscale fabrication of smart materials relying on the molecular self‐assembly of block copolymers (BCPs) has been recognized as a valuable platform for various next‐generation functional structures. In this Progress Report, the recent advances in the BCP self‐assembly process, which has paved the way for viable applications of emerging nanotechnologies, are highlighted. Effective light‐induced self‐assembly based on photothermal annealing of high‐χ BCPs and conformal 3D surface nanopa

The objective of this study was to evaluate the effect of 0.1% pilocarpine mouthwash in xerostomic patients. Sixty volunteers were randomly allocated to two groups. The experimental group used 0.1% pilocarpine solution, and the control group used 0.9% saline. The short- and long-term effects of pilocarpine were investigated by measuring the severity of oral dryness, minor salivary flow rates and unstimulated whole salivary flow rate at predetermined times. The severity of oral dryness was decrea

The development of devices that can be mechanically deformed in geometrical layouts, such as flexible/stretchable devices, is important for various applications. Conventional flexible/stretchable devices have been demonstrated using two-dimensional (2D) geometry, resulting in dimensional constraints on device operations and functionality limitations. Accordingly, expanding the dimensions in which such devices can operate and acquiring unique functionality that is difficult to implement in 2D pla

A four-leg pulse width modulation (PWM) voltage source converter (VSC) is used to supply three phase balanced voltage even under an unbalanced load condition in three phase four wire power distribution network. A novel carrier-based modulation technique for the converter is described with the concept of an offset voltage and also is extended to so called 'discontinuous PWM (DPWM)' to minimize switching losses of VSC. As a practical application example of the four-leg VSC, a line interactive unin