Hyung‐Min Lee

A power-efficient wireless stimulating system for a head-mounted deep brain stimulator (DBS) is presented. A new adaptive rectifier generates a variable DC supply voltage from a constant AC power carrier utilizing phase control feedback, while achieving high AC-DC power conversion efficiency (PCE) through active synchronous switching. A current-controlled stimulator adopts closed-loop supply control to automatically adjust the stimulation compliance voltage by detecting stimulation site potentia

We present an active full-wave rectifier with offset-controlled high speed comparators in standard CMOS that provides high power conversion efficiency (PCE) in high frequency (HF) range for inductively powered devices. This rectifier provides much lower dropout voltage and far better PCE compared to the passive on-chip or off-chip rectifiers. The built-in offset-control functions in the comparators compensate for both turn-on and turn-off delays in the main rectifying switches, thus maximizing t

A power-efficient wireless switched-capacitor based stimulating (SCS) system for electrical/optical deep brain stimulation (DBS) is presented. The SCS system efficiently charges storage capacitors directly from an inductive link and delivers accurately balanced charge to the tissue, improving the overall stimulator efficiency. In addition, the decaying exponential stimulus pulses generated by SCS can be more effective than conventional rectangular and ramp stimuli in activating neural tissue whe

Modern implantable microelectronic devices (IMDs) require higher performance and power efficiency to enable more efficacious therapies, particularly in neuro-prostheses such as retinal and cochlear implants [1]. Inductive power transmission across the skin is a viable solution for providing sufficient power to such IMDs without imposing size and power constraints of implanted batteries [2]. On the down side, unlike batteries that provide a stable power source, unexpected variations in the coils'

In this paper, we present a fully integrated active voltage doubler in CMOS technology using offset-controlled high speed comparators for extending the range of inductive power transmission to implantable microelectronic devices (IMD) and radio-frequency identification (RFID) tags. This active voltage doubler provides considerably higher power conversion efficiency (PCE) and lower dropout voltage compared to its passive counterpart and requires lower input voltage than active rectifiers, leading

We present an adaptive reconfigurable active voltage doubler (VD)/rectifier (REC) (VD/REC) in standard CMOS, which can adaptively change its topology to either a VD or a REC by sensing the output voltage, leading to more robust inductive power transmission over an extended range. Both active VD and REC modes provide much lower dropout voltage and far better power conversion efficiency (PCE) compared to their passive counterparts by adopting offset-controlled high-speed comparators that drive the

The 1,927-nm thulium fiber fractional laser is a safe, effective treatment for photoaging and melasma in Asians.

A power-efficient wireless capacitor charging system for inductively powered applications has been presented. A bank of capacitors can be directly charged from an ac source by generating a current through a series charge injection capacitor and a capacitor charger circuit. The fixed charging current reduces energy loss in switches, while maximizing the charging efficiency. An adaptive capacitor tuner compensates for the resonant capacitance variations during charging to keep the amplitude of the

Based on a theoretical proposition that public diplomacy can be explicated as management of organization–public relationship (OPR) between an organization concerned and foreign publics, practical and functional utility of OPR measures was empirically investigated in this preliminary study within a public diplomacy context involving the US embassy in Seoul and South Korean college students. Validating reliability and validity of Hon and J. E. Grunig's (1999 Hon , L. C. , & Grunig , J. E. ( 1999 )

An embedded DAC requires a large number of input transistors (=2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N+1</sup> for N-bit interpolation) in its amplifier. Moreover, the transistors require large width and length for accurate matching, leading to an area penalty in the amplifier for high bit interpolation (e.g. N>3). In this paper, an area-efficient and accurate interpolation method that uses variable-current control (VCC) for 10b mobile A

In this paper, we review recent advances in reverse engineering with an emphasis on FPGA devices and experimentally verified advantages and limitations of reverse engineering tools. The paper first introduces essential components for programming Xilinx FPGAs (Xilinx, San Jose, CA, USA), such as Xilinx Design Language (XDL), XDL Report (XDLRC), and bitstream. Then, reverse engineering tools (Debit, BIL, and Bit2ncd), which extract the bitstream from the external memory to the FPGA and utilize it

Ethylene‐vinyl acetate copolymer (EVA) with 40 wt.% vinyl acetate content (EVA40)/organoclay nanocomposites were prepared using a melt intercalation method with several different clay concentrations (2.5, 5.0, 7.5, and 10.0 wt.%). X‐ray diffraction confirmed the formation of exfoliated nanocomposite in all cases with disappearance of the characteristic peak corresponding to the d‐spacing of the pristine organoclay. Transmission electron microscopy studies also showed an exfoliated morphology of

Counterfeiting is a major issue plaguing global supply chains. In order to mitigate this problem, a wireless authentication tag is presented that implements a cryptographically secure pseudorandom number generator and authenticated encryption modes. The tag uses Keccak, the cryptographic core of SHA3, to update keys before each protocol invocation, limiting side-channel leakage. Power-glitch attacks are mitigated through state backup on ferroelectric capacitor-based nonvolatile flip-flops with a

The purpose of this study was to test the feasibility of using a switched-capacitor discharge stimulation (SCDS) system for electrical stimulation, and, subsequently, determine the overall energy saved compared to a conventional stimulator. We have constructed a computational model by pairing an image-based volume conductor model of the cat head with cable models of corticospinal tract (CST) axons and quantified the theoretical stimulation efficiency of rectangular and decaying exponential wavef