Effect of ASLR on Memory Duplicate Ratio in Cache-based Virtual Machine Live Migration

Guangyong Piao,오영섭,성백재,박찬익 대한임베디드공학회 2014 대한임베디드공학회논문지 Vol.9 No.4

Cache based live migration method utilizes a cache, which is accessible to both side (remote and local), to reduce the virtual machine migration time, by transferring only irredundant data. However, address space layout randomization (ASLR) is proved to reduce the memory duplicate ratio between targeted migration memory and the migration cache. In this pager, we analyzed the behavior of ASLR to find out how it changes the physical memory contents of virtual machines. We found that among six virtual memory regions, only the modification to stack influences the page-level memory duplicate ratio. Experiments showed that: (1) the ASLR does not shift the heap region in sub-page level; (2) the stack reduces the duplicate page size among VMs which performed input replay around 40MB, when ASLR was enabled; (3) the size of memory pages, which can be reconstructed from the fresh booted up state, also reduces by about 60MB by ASLR. With those observations, when applying cache-based migration method, we can omit the stack region. While for other five regions, even a coarse page-level redundancy data detecting method can figure out most of the duplicate memory contents.

Selective liquid-metal plating technique for stretchable biosensors

Guangyong Li(이광용),Xuan Wu(오선),Dong-Weon. Lee(이동원) 한국기계가공학회 2016 한국기계가공학회 춘추계학술대회 논문집 Vol.2016 No.4

A hybrid model of regional path loss of wireless signals through the wall

Guangyong Xi,Shizhen Lin,Dongyao Zou 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.9

Wall obstruction is the main factor leading to the non-line of sight (NLoS) error of indoor localization based on received signal strength indicator (RSSI). Modeling and correcting the path loss of the signals through the wall will improve the accuracy of RSSI localization. Based on electromagnetic wave propagation theory, the reflection and transmission process of wireless signals propagation through the wall is analyzed. The path loss of signals through wall is deduced based on power loss and RSSI definition, and the theoretical model of path loss of signals through wall is proposed. In view of electromagnetic characteristic parameters of the theoretical model usually cannot be accurately obtained, the statistical model of NLoS error caused by the signals through the wall is presented based on the log-distance path loss model to solve the parameters. Combining the statistical model and theoretical model, a hybrid model of path loss of signals through wall is proposed. Based on the empirical values of electromagnetic characteristic parameters of the concrete wall, the effect of each electromagnetic characteristic parameters on path loss is analyzed, and the theoretical model of regional path loss of signals through the wall is established. The statistical model and hybrid model of regional path loss of signals through wall are established by RSSI observation experiments, respectively. The hybrid model can solve the problem of path loss when the material of wall is unknown. The results show that the hybrid model can better express the actual trend of the regional path loss and maintain the pass loss continuity of adjacent areas. The validity of the hybrid model is verified by inverse computation of the RSSI of the extended region, and the calculated RSSI is basically consistent with the measured RSSI. The hybrid model can be used to forecast regional path loss of signals through the wall.

A novel watermarking scheme for authenticating individual data integrity of WSNs

Guangyong Gao,Min Wang 한국인터넷정보학회 2023 KSII Transactions on Internet and Information Syst Vol.17 No.3

The limited computing power of sensor nodes in wireless sensor networks (WSNs) and data tampering during wireless transmission are two important issues. In this paper, we propose a scheme for independent individual authentication of WSNs data based on digital watermarking technology. Digital watermarking suits well for WSNs, owing to its lower computational cost. The proposed scheme uses independent individual to generate a digital watermark and embeds the watermark in current data item. Moreover, a sink node extracts the watermark in single data and compares it with the generated watermark, thereby achieving integrity verification of data. Inherently, individual validation differs from the grouping-level validation, and avoids the lack of grouping robustness. The improved performance of individual integrity verification based on proposed scheme is validated through experimental analysis. Lastly, compared to other state-of-the-art schemes, our proposed scheme significantly reduces the false negative rate by an average of 5%, the false positive rate by an average of 80% of data verification, and increases the correct verification rate by 50% on average.

Reversible Watermarking with Adaptive Embedding Threshold Matrix

( Guangyong Gao ),( Yun-qing Shi ),( Xingming Sun ),( Caixue Zhou ),( Zongmin Cui ),( Liya Xu ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.9

In this paper, a new reversible watermarking algorithm with adaptive embedding threshold matrix is proposed. Firstly, to avoid the overflow and underflow, two flexible thresholds, TL and TR, are applied to preprocess the image histogram with least histogram shift cost. Secondly, for achieving an optimal or near optimal tradeoff between the embedding capacity and imperceptibility, the embedding threshold matrix, composed of the embedding thresholds of all blocks, is determined adaptively by the combination between the composite chaos and the average energy of Integer Wavelet Transform (IWT) block. As a non-liner system with good randomness, the composite chaos is suitable to search the optimal embedding thresholds. Meanwhile, the average energy of IWT block is calculated to adjust the block embedding capacity, and more data are embedded into those IWT blocks with larger average energy. The experimental results demonstrate that compared with the state-of-the-art reversible watermarking schemes, the proposed scheme has better performance for the tradeoff between the embedding capacity and imperceptibility.

Effect of ASLR on Memory Duplicate Ratio in Cache-based Virtual Machine Live Migration

Piao, Guangyong,Oh, Youngsup,Sung, Baegjae,Park, Chanik Institute of Embedded Engineering of Korea 2014 대한임베디드공학회논문지 Vol.9 No.4

Cache based live migration method utilizes a cache, which is accessible to both side (remote and local), to reduce the virtual machine migration time, by transferring only irredundant data. However, address space layout randomization (ASLR) is proved to reduce the memory duplicate ratio between targeted migration memory and the migration cache. In this pager, we analyzed the behavior of ASLR to find out how it changes the physical memory contents of virtual machines. We found that among six virtual memory regions, only the modification to stack influences the page-level memory duplicate ratio. Experiments showed that: (1) the ASLR does not shift the heap region in sub-page level; (2) the stack reduces the duplicate page size among VMs which performed input replay around 40MB, when ASLR was enabled; (3) the size of memory pages, which can be reconstructed from the fresh booted up state, also reduces by about 60MB by ASLR. With those observations, when applying cache-based migration method, we can omit the stack region. While for other five regions, even a coarse page-level redundancy data detecting method can figure out most of the duplicate memory contents.

‘구망 (救亡)”과 “계몽”으로 접근한 중국 다큐멘터리사진 약사

김광영 ( Guangyong Jin ) 한국기초조형학회 2019 기초조형학연구 Vol.20 No.3

본 연구는 중국의 다큐멘터리사진 역사를 “계몽”과 “구망(기울어져가는 나라를 구함)”의 이중주로 살펴본 것이다. 아울러 그것을 몇개 덩어리로 나누어서 살펴보았는데, 1) 먼저 다큐멘터리사진의 명칭의 함의와 그 수용사를 논한 다음 2) 중국적 상황속에서 다큐멘터리사진이 어떻게 정착 되었으며 3) 격동의 시대에 어떤 역사적 과정을 겪어왔으며 4) 현대다큐멘터리사진은 어떤 양상을 보여주는가가 그것이다. 아울러 본고는 다큐멘터리사진과 저널리즘(정치보도)사진으로 전유된 “다큐멘터리”사진의 역사를 대비시키면서 분석하고자 하였다. 이는 거대 서사와 유사미시서사의 관계로 중국 다큐멘터리사진의 역사를 깊이 있게 분석하기 위함이다. 아울러 “구망(救亡)”과 “계몽”의 관계로 관련 작품을 분절한 것은 다큐멘터리사진을 구체적인 역사적 사회적 지평에 놓기 위함이다. 본고는 1980년대와 1990년대까지를 연구범위로 할 것인데 이는 지면의 한계이기도 하거니와 또 그 이후의 다큐멘터리사진도 그것의 연장선에 서있기 때문이다. 기록성과 사실성을 중시하는 다큐멘터리사진은 중국적 상황 속에서 지속적인 변화와 발전을 가져왔는데, 이는 구체적인 역사적 상황 속에서 “시대성”과 “사실성”이 드러나는 과정이기도 하다. 결론적으로 다큐멘터리사진의 의미 분석은 예술가가 어떤 역사(시대)적 지평에 서서 사실을 어떤 시점으로 바라보는가에 대한 것이다. 바꾸어 말하면 “사실성”과 “기록성”은 간(間) “주관”적인 것만큼 간(間) “객관”적인 것이다. 이러한 입장에서 연구자는 “구망”과 “계몽”이란 시대적 기후(에피스테메)로 중국 다큐멘터리 사진약사를 재구성하고자 하였다. 끝으로 국내외적으로 중국다큐멘터리사진을 “구망”과 “계몽”으로 분석한 논문은 처음일 것이니 본고는 시론적 연구에 속할 것이다. This paper will observe the history of documentary photography in China from the perspectives of salvation and enlightenment. First of all, it will discuss the definition of documentary photography and its adaption in history. And then, it will answer how documentary photography was settled down in China, what kind of processes documentary photography has been experienced, and what kind of aspects it has presented in history. It will also contrast the histories of documentary photography and of “documentary photography”, which transforms into journal photography(or political photography). In doing so, the history of documentary photography in China could be studied in the relation between metanarrative and micronarrative. Besides, documentary photography will be discussed from the perspectives of salvation and enlightenment. The discussion would be limited in the specific historical and social context, ranging from 1980s and 1990s, because the documentary photography after 1980s and 1990s is the extension of the documentary photography from the 1980s and 1990s. Based on the belief that documentary photography could record the historical facts “correctly”, documentary photography has well developed in China. The study could reveal the senses of time and facts because of such specific context tangles with history, culture, and politics. Epistemologically speaking, the senses of time and facts would be changed with different ways of understanding things. In other words, the senses are also “subjective”. In conclusion, the semantic analysis of documentary photography is about how the artist perceives the historical facts. That is to say, the senses of “fact” and “document” are in-between “subjective” and “objective” perceptions. Therefore, this paper aims to reconstruct the history of documentary photography in China from the epistemic perspectives of salvation and enlightenment. Considering that this paper is the first attempt to perceive documentary photography in China from the perspectives of salvation and enlightenment at home and abroad, it could be regarded as a poetic study.

Combining Ultrasound-Mediated Intracellular Delivery with Microfluidics in Various Applications

Huang Guangyong,Lin Lin,Wu Shixiong,Dang Haojie,Cheng Xuesong,Liu Ying,You Hui 한국바이오칩학회 2024 BioChip Journal Vol.18 No.1

Ultrasound-mediated intracellular delivery is one of the popular technologies based on membrane rupture at present. To date, ultrasound directly acts on a large number of cells to achieve cargo delivery and has been widely used in drug deliv-ery, disease therapy and other fields. However, the existing macroscopic methods can no longer meet the requirements of accurate tracking and analysis and are prone to extensive cell damage and even death. With the rapid advancements in microfl uidic technologies, the combination of ultrasound and microfluidics (CUM) technology can effectively improve the delivery efficiency and cell survival rates. This new technology has rapidly become a new direction and focus of research. Thus, we analysed the mechanism of sonoporation and the effect of acoustic waves in a microfluidic channel. In addition, we reviewed the application of these new technologies in terms of structure and fabrication of ultrasound transducers and microfl uidic devices. As regards our main objective, we hope to help researchers better understand the future developments and the challenges of new technologies. With this review, researchers can promote the development of new technologies to solve the current challenges of intracellular delivery and advance clinical applications.

On the Collapse Resistance of the Levy Type and the Loop-Free Suspen-Dome Structures After Accidental Failure of Cables

Renjie Liu,Yao Zou,Guangyong Wang,Suduo Xue 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.2

Current Levy type suspen-domes use loop cables which are key elements and carry large tensions. The loop-free suspendome was proposed for improving the collapse resistance and reducing cable tensions. However, the collapse resistance of the loop-free suspen-dome after accidental failure of cables has not been verifi ed and its key element is not clear. In this paper, analysis on the collapse resistance of both the Levy type suspen-dome and the loop-free suspen-dome after accidental failure of cables is performed based on the AP method by considering dynamic eff ect and non-linearity. The displacements and residual bearing capacity of 34 cable-rupture schemes are discussed, the eff ect on the cable tension and failure mode are also analyzed. It turns out that collapse resistance of the loop-free suspen-dome is better than the Levy type suspen-dome. The failure of cables does not infl uence the tension of remaining cables obviously so that the loop-free cable-strut system has suffi cient stiff ness and provides support and restraint for the reticulated shell. The most important cable in the loop-free suspen-dome is located in the outermost layer of the cable-strut system. It is also found that whether progressive collapse of the suspen-dome occurs after accidental failure of cables depends on both the bearing capacity of the reticulated shell and the residual contribution of the cable-strut system.

Interface damage mechanism of rubber cord composite material

Xiaohui Guo,Xiaojing Yuan,Guangyong Liu,Hefang Qiu,Fanfan Cui 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.1

In order to study the interface failure mechanism of rubber cord composites laid at symmetrical angles, a representativevolume element was established by the finite element method to simulate the stress distribution at the mesoscopic level ofrubber cord composites. The energy-based power law is used to simulate the damage evolution of the cord-rubber interface. The results show that the interface damage is caused by the torque that the cord bears during the stretching process, and theinterface assumes the role of transmitting torque in this process, so the failure occurred.The initial interface stiffness is a vitalbonding interface parameter that affects the interface damage evolution, and the initial stiffness is positively correlated withthe interface damage evolution variable. The increase in the included angle of the cord will cause the torque on the cord toincrease, resulting in aggravated interface failure.