Ji-Soo Choi

Electric Network Frequency (ENF) analysis is a promising forensic technique for authenticating digital recordings and detecting tampering within the recordings. The validity of ENF analysis heavily relies on high-quality ENF signals extracted from multimedia recordings. In this paper, we propose an ENF signal extraction method for rolling shutter acquired videos using periodic zero-padding. Our analysis shows that the extracted ENF signals using the proposed method are not distorted and the comp

This work presents a qubit controller IC based on the direct synthesis. The IC consists of six independently-working pulse modulators utilizing the same LO frequency. We propose a sinusoid-shaping nonlinear DAC followed by a linear interpolating DAC to improve both of energy and hardware efficiencies. The implemented IC in 40nm CMOS is verified by superconducting qubit operations with Rabi and Ramsey oscillations while consuming power of < 1/60 compared with the previous state-of-the-art.

Electric network frequency (ENF) analysis is a promising forensic technique for authenticating multimedia recordings and detecting tampering. The validity of the ENF analysis heavily relies on the capability of extracting high-quality ENF signals from multimedia recordings. This paper analyzes and compares two representative methods for extracting ENF signals from visual signals acquired by cameras using the rolling-shutter mechanism. The first method proposed in prior work, <italic xmlns:mml="h

The recent growth of connected car technology encourages IT and vehicle organizations to develop advanced vehicle-to-cloud (V2C) services such as driving assistance, infotainment, and vehicle maintenance. However, since their performances highly depend on the resource configuration and regional characteristics, it is almost impossible to examine the service feasibility in every candidate region by constructing real testbeds. To overcome this problem, we present an integrated road traffic-network

Geotagging images of interest are increasingly important to law enforcement, national security, and journalism. Today, many images do not carry location tags that are trustworthy and resilient to tampering; and landmark-based visual clues may not be readily present in every image, especially in those taken indoors. In this paper, we exploit an environmental signature from the power grid, the electric network frequency (ENF) signal, which can be inherently captured in a sensing stream at the time

To broaden the range of measurable pesticides for stable isotope analysis (SIA), we tested whether SIA of the anthranilic diamides cyantraniliprole (CYN) and chlorantraniliprole (CHL) can be achieved under elemental analyzer/isotope ratio mass spectrometry with compound purification in high-performance liquid chromatography (HPLC). Using this method, carbon isotope compositions were measured in pesticide residues extracted from plants (lettuce) grown indoors in potting soil that were treated wit

It is essential for multiuser networks to determine how to efficiently and fairly allocate shared and limited resources. Moreover, it is critical to optimally allocate these resources while ensuring quality of service requirements for users who require tolerable levels of quality. In this letter, we adopt a game-theoretic approach, referred to as the Nash bargaining solution (NBS), for resource allocation across multiple users. While the NBS can provide a fair and optimal resource allocation, fi

The effect of thickness change of a tungsten heavy alloy (WHA) on its dynamic behaviors has been studied. Exploding bridgwire (EBW) detonator has been used to drive the alloy plate. The particle velocity at the rear free surface of a specimen was measured by means of VISAR. Simple experimental technique has been introduced herein to obtain the Hugoniot elastic limit and spall strength of materials in the form of small disc plate (diameter of ∼7 mm) with varying thickness. The peak pressure decay

Abstract There has been an increasing amount of work surrounding the Electric Network Frequency (ENF) signal, an environmental signature captured by audio and video recordings made in locations where there is electrical activity. ENF is the frequency of power distribution networks, 60 Hz in most of the Americas and 50 Hz in most other parts of the world. The ubiquity of this power signature and the appearance of its traces in media recordings motivated its early application toward time–location

The remarkable advances of quantum computation technology with superconducting qubits based on circuit quantum electrodynamics (QED) architecture have been achieved by improving control, protection and measurement of the quantum states at the same time. At the heart of all these quantum operations, the significant enhancement of the qubit coherence time during the last decades was the key. Even after all these advances, the coherence and relaxation time of superconducting qubits still requires f

Submitted to IEEE Transactions on Information Forensics and Security (T-IFS). Under revision.

In this paper, we present an efficient algorithm for Nash bargaining solution (NBS). While NBS can be deployed to allocate limited resources to multiple users fairly and optimally, it requires significantly high computational complexity to find NBS, in particular, as the number of users becomes large. In order to reduce the complexity for NBS, we propose to adopt a coalition formation based approach, which is efficient for large number of users. In addition, we define a coalition utility functio

We investigated decoherence sources in Ramsay measurement, which represents the depahsing time in superconducting transmon qubit in 3D cavity. The dephasing time is strongly influenced by the measurement environment in addition to the qubit itself. We studied the influence of the drive and readout pulses in time domain measurement. We will also discuss the trajectory measurement where the qubit state is represented on the bloch sphere. We expect the improvement of qubit operation including phase