Tatsuya KOBAYASHI Keita YASUTOMI Naoki TAKADA Shoji KAWAHITO
This paper presents a high-NIR sensitivity SOI-gate lock-in pixel with improved modulation contrast. The proposed pixel has a shallow buried channel and intermediate gates to create both a high lateral electric field and a potential barrier to parasitic light sensitivity. Device simulation results showed that parasitic light sensitivity reduced from 13.7% to 0.13% compared to the previous structure.
Yuki ABE Kazutoshi KOBAYASHI Jun SHIOMI Hiroyuki OCHI
Energy harvesting has been widely investigated as a potential solution to supply power for Internet of Things (IoT) devices. Computing devices must operate intermittently rather than continuously, because harvested energy is unstable and some of IoT applications can be periodic. Therefore, processors for IoT devices with intermittent operation must feature a hibernation mode with zero-standby-power in addition to energy-efficient normal mode. In this paper, we describe the layout design and measurement results of a nonvolatile standard cell memory (NV-SCM) and nonvolatile flip-flops (NV-FF) with a nonvolatile memory using Fishbone-in-Cage Capacitor (FiCC) suitable for IoT processors with intermittent operations. They can be fabricated in any conventional CMOS process without any additional mask. NV-SCM and NV-FF are fabricated in a 180nm CMOS process technology. The area overhead by nonvolatility of a bit cell are 74% in NV-SCM and 29% in NV-FF, respectively. We confirmed full functionality of the NV-SCM and NV-FF. The nonvolatile system using proposed NV-SCM and NV-FF can reduce the energy consumption by 24.3% compared to the volatile system when hibernation/normal operation time ratio is 500 as shown in the simulation.
Takuya WADATSUMI Kohei KAWAI Rikuu HASEGAWA Kikuo MURAMATSU Hiromu HASEGAWA Takuya SAWADA Takahito FUKUSHIMA Hisashi KONDO Takuji MIKI Makoto NAGATA
This paper presents on-chip characterization of electrostatic discharge (ESD) impacts applied on the Si-substrate backside of a flip-chip mounted integrated circuit (FC-IC) chip. An FC-IC chip has an open backside and there is a threat of reliability problems and malfunctions caused by the backside ESD. We prepared a test FC-IC chip and measured Si-substrate voltage fluctuations on its frontside by an on-chip monitor (OCM) circuit. The voltage surges as large as 200mV were observed on the frontside when a 200-V ESD gun was irradiated through a 5kΩ contact resistor on the backside of a 350μm thick Si substrate. The distribution of voltage heights was experimentally measured at 20 on-chip locations among thinned Si substrates up to 40μm, and also explained in full-system level simulation of backside ESD impacts with the equivalent models of ESD-gun operation and FC-IC chip assembly.
Ryozo TAKAHASHI Takuji MIKI Makoto NAGATA
This brief presents a side-channel attack (SCA) technique on a high-speed asynchronous successive approximation register (SAR) analog-to-digital converter (ADC). The proposed dual neural network based on multiple noise waveforms separately discloses sign and absolute value information of input signals which are hidden by the differential structure and high-speed asynchronous operation. The target SAR ADC and on-chip noise monitors are designed on a single prototype chip for SCA demonstration. Fabricated in 40 nm, the experimental results show the proposed attack on the asynchronous SAR ADC successfully restores the input data with a competitive accuracy within 300 mV rms error.
Xiaoman LIU Yujie GAO Yuan HE Xiaohan YUE Haiyan JIANG Xibo WANG
The complexity and scale of Networks-on-Chip (NoCs) are growing as more processing elements and memory devices are implemented on chips. However, under strict power budgets, it is also critical to lower the power consumption of NoCs for the sake of energy efficiency. In this paper, we therefore present three novel input unit designs for on-chip routers attempting to shrink their power consumption while still conserving the network performance. The key idea behind our designs is to organize buffers in the input units with characteristics of the network traffic in mind; as in our observations, only a small portion of the network traffic are long packets (composed of multiple flits), which means, it is fair to implement hybrid, asymmetric and reconfigurable buffers so that they are mainly targeting at short packets (only having a single flit), hence the smaller power consumption and area overhead. Evaluations show that our hybrid, asymmetric and reconfigurable input unit designs can achieve an average reduction of energy consumption per flit by 45%, 52.3% and 56.2% under 93.6% (for hybrid designs) and 66.3% (for asymmetric and reconfigurable designs) of the original router area, respectively. Meanwhile, we only observe minor degradation in network latency (ranging from 18.4% to 1.5%, on average) with our proposals.
Joong-Won SHIN Masakazu TANUMA Shun-ichiro OHMI
In this research, we investigated the threshold voltage (VTH) control by partial polarization of metal-ferroelectric-semiconductor field-effect transistors (MFSFETs) with 5 nm-thick nondoped HfO2 gate insulator utilizing Kr-plasma sputtering for Pt gate electrode deposition. The remnant polarization (2Pr) of 7.2 μC/cm2 was realized by Kr-plasma sputtering for Pt gate electrode deposition. The memory window (MW) of 0.58 V was realized by the pulse amplitude and width of -5/5 V, 100 ms. Furthermore, the VTH of MFSFET was controllable by program/erase (P/E) input pulse even with the pulse width below 100 ns which may be caused by the reduction of leakage current with decreasing plasma damage.
Shimpei NISHIYAMA Kimihiko KATO Yongxun LIU Raisei MIZOKUCHI Jun YONEDA Tetsuo KODERA Takahiro MORI
We have proposed and demonstrated a device fabrication process of physically defined quantum dots utilizing electron beam lithography employing a negative-tone resist toward high-density integration of silicon quantum bits (qubits). The electrical characterization at 3.8K exhibited so-called Coulomb diamonds, which indicates successful device operation as single-electron transistors. The proposed device fabrication process will be useful due to its high compatibility with the large-scale integration process.
Pengfei GAO Xiaoying TIAN Yannan SHI
The transfer distance of the wireless power transfer (WPT) system with relay coil is longer, so this technology have a better practical perspective. But the location of the relay coil has a great impact on the transmission efficiency of the WPT system, and it is not easy to analyze. In order to research the influence law of the relay coil location on the transmission efficiency and obtain the optimal location, the paper firstly proposes the concept of relay coil location factor. And based on the location factor, a novel method for studying the influence of the relay coil location on the transmission efficiency is proposed. First, the mathematical model between the transmission efficiency and the location factor is built. Next, considering the transfer distance, coil radius, coil turns and load resistance, a lot of simulations are carried out to analyze the influence of the location factor on the transmission efficiency, respectively. The influence law and the optimal location factor were obtained with different parameters. Finally, a WPT system with relay coil was built for experiments. And the experiment results verify that the theoretical analysis is correct and the proposed method can simplify the analysis progress of the influence of relay coil location on the transmission efficiency. Moreover, the proposed method and the research conclusions can provide guidance for designing the multiple coils structure WPT system.
Akira KUBOTA Kazuya KODAMA Daiki TAMURA Asami ITO
Focal stacks (FS) have attracted attention as an alternative representation of light field (LF). However, the problem of reconstructing LF from its FS is considered ill-posed. Although many regularization methods have been discussed, no method has been proposed to solve this problem perfectly. This paper showed that the LF can be perfectly reconstructed from the FS through a filter bank in theory for Lambertian scenes without occlusion if the camera aperture for acquiring the FS is a Cauchy function. The numerical simulation demonstrated that the filter bank allows perfect reconstruction of the LF.
A feedback node set (FNS) of a graph is a subset of the nodes of the graph whose deletion makes the residual graph acyclic. By finding an FNS in an interconnection network, we can set a check point at each node in it to avoid a livelock configuration. Hence, to find an FNS is a critical issue to enhance the dependability of a parallel computing system. In this paper, we propose a method to find FNS's in n-pancake graphs and n-burnt pancake graphs. By analyzing the types of cycles proposed in our method, we also give the number of the nodes in the FNS in an n-pancake graph, (n-2.875)(n-1)!+1.5(n-3)!, and that in an n-burnt pancake graph, 2n-1(n-1)!(n-3.5).
Shiling SHI Stefan HOLST Xiaoqing WEN
High power dissipation during scan test often causes undue yield loss, especially for low-power circuits. One major reason is that the resulting IR-drop in shift mode may corrupt test data. A common approach to solving this problem is partial-shift, in which multiple scan chains are formed and only one group of scan chains is shifted at a time. However, existing partial-shift based methods suffer from two major problems: (1) their IR-drop estimation is not accurate enough or computationally too expensive to be done for each shift cycle; (2) partial-shift is hence applied to all shift cycles, resulting in long test time. This paper addresses these two problems with a novel IR-drop-aware scan shift method, featuring: (1) Cycle-based IR-Drop Estimation (CIDE) supported by a GPU-accelerated dynamic power simulator to quickly find potential shift cycles with excessive peak IR-drop; (2) a scan shift scheduling method that generates a scan chain grouping targeted for each considered shift cycle to reduce the impact on test time. Experiments on ITC'99 benchmark circuits show that: (1) the CIDE is computationally feasible; (2) the proposed scan shift schedule can achieve a global peak IR-drop reduction of up to 47%. Its scheduling efficiency is 58.4% higher than that of an existing typical method on average, which means our method has less test time.
Takao YAMANAKA Tatsuya SUZUKI Taiki NOBUTSUNE Chenjunlin WU
Omni-directional images have been used in wide range of applications including virtual/augmented realities, self-driving cars, robotics simulators, and surveillance systems. For these applications, it would be useful to estimate saliency maps representing probability distributions of gazing points with a head-mounted display, to detect important regions in the omni-directional images. This paper proposes a novel saliency-map estimation model for the omni-directional images by extracting overlapping 2-dimensional (2D) plane images from omni-directional images at various directions and angles of view. While 2D saliency maps tend to have high probability at the center of images (center bias), the high-probability region appears at horizontal directions in omni-directional saliency maps when a head-mounted display is used (equator bias). Therefore, the 2D saliency model with a center-bias layer was fine-tuned with an omni-directional dataset by replacing the center-bias layer to an equator-bias layer conditioned on the elevation angle for the extraction of the 2D plane image. The limited availability of omni-directional images in saliency datasets can be compensated by using the well-established 2D saliency model pretrained by a large number of training images with the ground truth of 2D saliency maps. In addition, this paper proposes a multi-scale estimation method by extracting 2D images in multiple angles of view to detect objects of various sizes with variable receptive fields. The saliency maps estimated from the multiple angles of view were integrated by using pixel-wise attention weights calculated in an integration layer for weighting the optimal scale to each object. The proposed method was evaluated using a publicly available dataset with evaluation metrics for omni-directional saliency maps. It was confirmed that the accuracy of the saliency maps was improved by the proposed method.
Jonghyeok YOU Heesoo KIM Kilho LEE
This paper proposes a fault-resilient ROS platform supporting rapid fault detection and recovery. The platform employs heartbeat-based fault detection and node replication-based recovery. Our prototype implementation on top of the ROS Melodic shows a great performance in evaluations with a Nvidia development board and an inverted pendulum device.
With the emergence of a large quantity of data in science and industry, it is urgent to improve the prediction accuracy and reduce the high complexity of Gaussian process regression (GPR). However, the traditional global approximation and local approximation have corresponding shortcomings, such as global approximation tends to ignore local features, and local approximation has the problem of over-fitting. In order to solve these problems, a large-scale Gaussian process regression algorithm (RFFLT) combining random Fourier features (RFF) and local approximation is proposed. 1) In order to speed up the training time, we use the random Fourier feature map input data mapped to the random low-dimensional feature space for processing. The main innovation of the algorithm is to design features by using existing fast linear processing methods, so that the inner product of the transformed data is approximately equal to the inner product in the feature space of the shift invariant kernel specified by the user. 2) The generalized robust Bayesian committee machine (GRBCM) based on Tsallis mutual information method is used in local approximation, which enhances the flexibility of the model and generates a sparse representation of the expert weight distribution compared with previous work. The algorithm RFFLT was tested on six real data sets, which greatly shortened the time of regression prediction and improved the prediction accuracy.
Wan Yeon LEE Yun-Seok CHOI Tong Min KIM
We propose a quantitative measurement technique of video forgery that eliminates the decision burden of subtle boundary between normal and tampered patterns. We also propose the automatic adjustment scheme of spatial and temporal target zones, which maximizes the abnormality measurement of forged videos. Evaluation shows that the proposed scheme provides manifest detection capability against both inter-frame and intra-frame forgeries.
Koji NAKAO Katsunari YOSHIOKA Takayuki SASAKI Rui TANABE Xuping HUANG Takeshi TAKAHASHI Akira FUJITA Jun'ichi TAKEUCHI Noboru MURATA Junji SHIKATA Kazuki IWAMOTO Kazuki TAKADA Yuki ISHIDA Masaru TAKEUCHI Naoto YANAI
In this paper, we developed the latest IoT honeypots to capture IoT malware currently on the loose, analyzed IoT malware with new features such as persistent infection, developed malware removal methods to be provided to IoT device users. Furthermore, as attack behaviors using IoT devices become more diverse and sophisticated every year, we conducted research related to various factors involved in understanding the overall picture of attack behaviors from the perspective of incident responders. As the final stage of countermeasures, we also conducted research and development of IoT malware disabling technology to stop only IoT malware activities in IoT devices and IoT system disabling technology to remotely control (including stopping) IoT devices themselves.
Shunta TERUI Katsuhisa YAMANAKA Takashi HIRAYAMA Takashi HORIYAMA Kazuhiro KURITA Takeaki UNO
We are given a set S of n points in the Euclidean plane. We assume that S is in general position. A simple polygon P is an empty polygon of S if each vertex of P is a point in S and every point in S is either outside P or a vertex of P. In this paper, we consider the problem of enumerating all the empty polygons of a given point set. To design an efficient enumeration algorithm, we use a reverse search by Avis and Fukuda with child lists. We propose an algorithm that enumerates all the empty polygons of S in O(n2|ε(S)|)-time, where ε(S) is the set of empty polygons of S. Moreover, by applying the same idea to the problem of enumerating surrounding polygons of a given point set S, we propose an enumeration algorithm that enumerates them in O(n2)-delay, while the known algorithm enumerates in O(n2 log n)-delay, where a surroundingpolygon of S is a polygon such that each vertex of the polygon is a point in S and every point in S is either inside the polygon or a vertex of the polygon.
Hiroshi FUJIWARA Masaya KAWAGUCHI Daiki TAKIZAWA Hiroaki YAMAMOTO
The bin packing problem is a problem of finding an assignment of a sequence of items to a minimum number of bins, each of capacity one. An online algorithm for the bin packing problem is an algorithm that irrevocably assigns each item one by one from the head of the sequence. Gutin, Jensen, and Yeo (2006) considered a version in which all items are only of two different sizes and the online algorithm knows the two possible sizes in advance, and gave an optimal online algorithm for the case when the larger size exceeds 1/2. In this paper we provide an optimal online algorithm for some of the cases when the larger size is at most 1/2, on the basis of a framework that facilitates the design and analysis of algorithms.
There are two types of elliptic curves, ordinary elliptic curves and supersingular elliptic curves. In 2012, Sutherland proposed an efficient and almost deterministic algorithm for determining whether a given curve is ordinary or supersingular. Sutherland's algorithm is based on sequences of isogenies started from the input curve, and computation of each isogeny requires square root computations, which is the dominant cost of the algorithm. In this paper, we reduce this dominant cost of Sutherland's algorithm to approximately a half of the original. In contrast to Sutherland's algorithm using j-invariants and modular polynomials, our proposed algorithm is based on Legendre form of elliptic curves, which simplifies the expression of each isogeny. Moreover, by carefully selecting the type of isogenies to be computed, we succeeded in gathering square root computations at two consecutive steps of Sutherland's algorithm into just a single fourth root computation (with experimentally almost the same cost as a single square root computation). The results of our experiments using Magma are supporting our argument; for cases of characteristic p of 768-bit to 1024-bit lengths, our proposed algorithm for characteristic p≡1 (mod 4) runs in about 61.5% of the time and for characteristic p≡3 (mod 4) also runs in about 54.9% of the time compared to Sutherland's algorithm.
Authenticated Key Exchange (AKE) is a cryptographic protocol to share a common session key among multiple parties. Usually, PKI-based AKE schemes are designed to guarantee secrecy of the session key and mutual authentication. However, in practice, there are many cases where mutual authentication is undesirable such as in anonymous networks like Tor and Riffle, or difficult to achieve due to the certificate management at the user level such as the Internet. Goldberg et al. formulated a model of anonymous one-sided AKE which guarantees the anonymity of the client by allowing only the client to authenticate the server, and proposed a concrete scheme. However, existing anonymous one-sided AKE schemes are only known to be secure in the random oracle model. In this paper, we propose generic constructions of anonymous one-sided AKE in the random oracle model and in the standard model, respectively. Our constructions allow us to construct the first post-quantum anonymous one-sided AKE scheme from isogenies in the standard model.