김용신 교수

CMK-3/CNT supercapacitors exhibit sufficiently fast response speed and high areal capacitance for AC line filtering.

The performance of switching devices such as display driver ICs is degraded by large power supply noise at switching frequencies from a few hundreds of kilohertz to a few megahertz. In order to minimize the power supply noise, a low-dropout (LDO) regulator with higher power supply rejection (PSR) is essential. In this brief, a capless LDO regulator with a negative capacitance circuit and voltage damper is proposed for enhancing PSR and figure of merit (FOM), respectively, in switching devices. T

When conventional maximum power point tracking (MPPT) techniques are required to operate fast under rapidly changing environmental conditions, a large power loss can be caused by slow tracking speed, output power fluctuation, or additionally required ad hoc parameters. This paper proposes a fast and efficient MPPT technique that minimizes the power loss with the adaptively binary-weighted step (ABWS) followed by the monotonically decreased step (MDS) without causing output power fluctuation or r

This paper presents a direct digital frequency synthesizer (DDFS) based on the nonlinear DAC with a maximum operating frequency of 2 GHz. This work proposes three design methods to enhance the performance of a DDFS. First, a multi-level momentarily activated bias is proposed to reduce power dissipation in the phase accumulator. Second, a coarse phase-based consecutive fine amplitude grouping scheme is presented to reduce hardware complexity and power consumption in the digital decoder. Third, th

ABSTRACT In this paper, concentrating photovoltaic (CPV) systems coupled with various inverter configurations are modeled, compared, and tested. Because CPV systems use optics to concentrate sunlight onto highly efficient PV cells, the systems are affected not only by mismatches in the I–V characteristics among individual PV cells but also by the electro‐optical mismatches of each concentrator. The best way to minimize power losses by these mismatches is having higher quality controls in alignin

ABSTRACT Concentrating photovoltaic solar power plants using dual‐axis trackers are in increasing demand. In a utility‐scale photovoltaic system, both capacity factor and ground coverage ratio are widely used to characterize systems in view of the land use efficiency. Current system modeling approaches lack accurate location‐specific direct normal irradiance (DNI), miss a reliable electrical model for power optimization and conversion and are inadequate for optimizing the tracker array configura

ABSTRACT This paper presents three key factors that cause system mismatches and power losses in high‐concentration photovoltaic (HCPV) systems. The first factor is the I–V mismatch within a module, similar to the manufacturing mismatches in conventional photovoltaic modules. The second factor is the misalignments amongst modules, and the third factor is the tracking control. Unlike in the conventional photovoltaic systems, the second and the third factors in HCPV systems introduce larger electro

The conventional infrared (IR) proximity-based three-directional (3D) motion gesture sensors (MGSs) detect hand motion by using either a single IR LED and multiple photosensors or multiple IR LEDs and a single photosensor. Since an IR LED is the most power hungry component, MGSs with a single IR LED and multiple photosensors are preferred for low-power applications. In this configuration, the recognition rate of an MGS is the function of the space between each photosensor. In order to achieve a

This letter presents a dual plate capacitive proximity sensor (PS) that is integrated into a single chip with high environmental noise immunity. To efficiently reject environmental noise, the proposed PS employs two noise rejection techniques: 1) the use of a switched-charge amplifier and 2) synchronous sampling/filtering technique. The proposed PS is fabricated using a standard CMOS 0.5- μm process, and it occupies an area of 0.7 mm × 0.3 mm. Experimental results show that the proposed PS can d

This study investigates the characteristics of a novel origami-based, elastomeric actuator and a soft gripper, which are controlled by hand gestures that are recognized through machine learning algorithms. The lightweight paper-elastomer structure employed in this research exhibits distinct actuation features in four key areas: (1) It requires approximately 20% less pressure for the same bending amplitude compared to pneumatic network actuators (Pneu-Net) of equivalent weight, and even less pres

Conventional capless digital low-dropout (DLDO) regulators adopt either a high-speed clock or the burst mode at the expense of a larger quiescent current in order to overcome the degradation of the load transient response caused by the absence of an external capacitor, which causes high power consumption. In this paper, a capless DLDO regulator with a self-clocking burst logic for ultralow power applications is proposed. The selfgenerated clock in the burst mode of the proposed burst logic is ac

This paper presents a message queue telemetry transport (MQTT) broker with priority support for emergency events in the Internet of Things (IoT), which is abbreviated p-MQTT. To support the timely and reliable message delivery of emergency events, the p-MQTT classifies the published messages coming into the broker server and controls their priority according to the classification results. To this end, the p-MQTT consists of three components: virtual queue, classification, and priority control. T

This paper presents a low-power and small-size motion gesture sensor (MGS) based on an active infrared (IR) proximity sensor. While conventional proximity-based MGSs require two LEDs (the most power-hungry components) and one photodiode, the proposed MGS eliminates one of LEDs at the expense of an additional photodiode as a separate channel. In conjunction with an optical block that limits the field-of-view of each photodiode, the power consumption and area of the proposed MGS can be reduced by