Unmanned aerial vehicle remotely sensed datasets, a reference dataset for coastal topography change and shoreline analysis

To analyze tendency of temporal and spatial change of coast using long-term topography and shoreline change data is important. In this study, high-resolution digital elevation model and orthorectified image data were generated using rotary-wing UAV(unmanned aerial vehicle) system for coastal topography and shoreline change analysis. The UAV system has advantage of low cost and high efficiency compared to satellite remote sensing platform so UAV system easily acquire time series image data. The spatial resolution of generated digital elevation model and orthorectified images are very high, in centimeter. Therefore, the above image data can be used in various fields of remote sensing and geography such as detailed coastal topography

A 32 x 30 SPAD-Based Scanless LiDAR Sensor with In-Pixel Histogram Array

Department of Electrical EngineeringRecently, low cost image sensors have been rapidly developed and applied to various applications. Particularly, the interest in self-driving technology that can drive without a driver beyond the common sense that such applications just help the driver to drive gets attention. Many sensors are required to accurately detect the surrounding situation, and in particular, a LiDAR sensor capable of quickly and accurately measuring mid-range detection is essential to prevent immediate accidents. However, the current LiDAR sensors are expensive due to technical problems with process and rotation issue. It is urgent to introduce a low-cost 3D LiDAR sensor to solve this problem. A single photon avalanche diode(SPAD) is a sensitive device that can generate a signal in response to a single photon and measure a long distance. However, since the SNR of the SPAD is low, histogram which solves the problem through numerous measurements is required. Unfortunately, pixel array cannot be designed due to a memory of histogram, and then SPAD-based LiDAR sensors are currently used as a line sensor. Line sensors using scanning method result in low frame rate, high structural cost for rotation, and low durability issues. This thesis is based on a new concept using a binary search, a successive approximation registrar (SAR) histogram technique, which eliminates the histogram memory and then designs a low-cost solid-state SPAD-based LiDAR sensor with small size in-pixel histogram. And in order to solve the problem of increasing measurement by eliminating memory, the problem was solved by exponential counting by measuring spatiotemporal correlation using multi-SPADs. A 30 x 32 in-pixel histogram array and associated circuitry have been designed in a 0.11um DBH CMOS process. The sensor has dynamic range of 96m and 0.75m precision for coarse resolution sensor with conventional p-well guard ring (GR) SPAD and advanced virtual guard-ring for high spec dark count rate (DCR) photon detection probability (PDP), 7%, at infrared (IR) -wave. The in-pixel histogram occupies 165um x 115um area by eliminating memory for histogram.clos

A CMOS LiDAR Sensor with In-Pixel Zoom Histogramming Time-to-Digital Converter

Department of Electrical Engineeringclos

Real-time Power Line Detection Network using Visible Light and Infrared Images

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A Low Noise Single-Slope ADC with Signal-Dependent Multiple Sampling Technique

A low noise single-slope analog-to-digital converter (SS-ADC) is presented employing a signal-dependent multiple sampling scheme for low-light imaging and high-accuracy ranging. The SS-ADC adopts multiple ramps to convert the signal of a pixel several times to average out random noise of readout circuits, improving a signal-to-noise ratio without any penalty on a readout time. The prototype SS-ADC fabricated in standard 0.11 ??m CIS process with an indirect time-of-flight pixel array improves a depth accuracy up to about 40% at a long distance

Certified Malware in South Korea: A Localized Study of Breaches of Trust in Code-Signing PKI Ecosystem

Code-signing PKI ecosystems are vulnerable to abusers. Kim et al. reported such abuse cases, e.g., malware authors misused the stolen private keys of the reputable code-signing certificates to sign their malicious programs. This certified malware exploits the chain of the trust established in the ecosystem and helps an adversary readily bypass security mechanisms such as anti-virus engines. Prior work analyzed the large corpus of certificates collected from the wild to characterize the security problems. However, this practice was typically performed in a global perspective and often left the issues that could happen at a local level behind. Our work revisits the investigations conducted by previous studies with a local perspective. In particular, we focus on code-signing certificates issued to South Korean companies. South Korea employs the code-signing PKI ecosystem with its own regional adaptations; thus, it is a perfect candidate to make a comparison. To begin with, we build a data collection pipeline and collect 455 certificates issued for South Korean companies and are potentially misused. We analyze those certificates based on three dimensions: (i) abusers, (ii) issuers, and (iii) the life-cycle of the certificate. We first identify that the strong regulation of a government can affect the market share of CAs. We also observe that several problems in certificate revocation: (i) the certificates had issued by local companies that closed the code-signing business still exist, (ii) only 6.8% of the abused certificates are revoked, and (iii) eight certificates are not revoked properly. All of those could lead to extending the validity of certified malware in the wild. Moreover, we show that the number of abuse cases is high in South Korea, even though it has a small population. Our study implies that Korean security practitioners require immediate attention to code-signing PKI abuse cases to safeguard the entire ecosystem

CMOS depth sensor with programmable filter circuits for environment-adaptive noise suppression

This Letter introduces a CMOS depth sensor with a multi-resolution single-photon avalanche diode (SPAD) array and area-efficient filter circuit with a programmable reference for environment-adaptive noise suppression. Four SPADs compose a macro-pixel for detecting targets at a short distance with high resolution, whereas 4 ?? 4 SPADs are reconfigured to a super-pixel for a long distance with enhanced signal-to-noise ratio. To provide environment-adaptive noise suppression in the miniaturised SPAD array, an area-efficient filter circuit with a programmable reference is proposed: a digital macro-filter corresponding to a macro-pixel and an analogue super filter corresponding to a super-pixel. The prototype chip was fabricated with a 110 nm CMOS image-sensor process, including 128 SPAD farm arrays and 128 analogue front-end circuits. With high background light of over 90 klx and a high dark-count rate of over 27.1 kHz, the time-of-flight could be measured by filtering out invalid pulses from noise without using multiple time-to-digital converters per pixel, which enables the implementation of miniaturised LiDAR-sensor systems on a chip

7.2 A 48 ??4013.5 mm Depth Resolution Flash LiDAR Sensor with In-Pixel Zoom Histogramming Time-to-Digital Converter

3D imaging technologies have become prevalent for diverse applications such as user identification, interactive user interfaces with AR/VR devices, and self-driving cars. Direct time-of-flight (D-ToF) systems, LiDAR sensors, are desirable for long-distance measurements in outdoor environments because they offer high sensitivity to weak reflected light and high immunity to background light thanks to the spatiotemporal correlation of SPADs [1], [2]. SPAD-based LiDAR sensors suffer from a large amount of ToF data generated by complicated time-to-digital converters (TDC), resulting in limited spatial resolution and frame rate compared with indirect ToF (I-ToF) sensors. Recently, LiDAR sensors embedding histogramming TDCs have been reported to generate depth information to reduce the required output bandwidth [3]-[6]. However, they still adopt a large number of memories in pixel, a complicated signal processor, or a column-parallel TDC scheme with scanning optics. ?? 2021 IEEE