가시광선-적외선 영역 내 능동 위장을 위한 열전 기반 인공 피부에 관한 연구

학위논문(박사) -- 서울대학교대학원 : 공과대학 기계항공공학부, 2023. 2. 고승환.Cephalopods inspired many researchers with distinctive camouflage ability from other species which is to hide in any background readily in both infrared (IR) and visible spectrum, but this still remains a conundrum. In this study, the author developed a flexible multispectral imperceptible skin-like device that actively imitates the surrounding environment, both in IR-visible integrated spectrum only by simple temperature control in the bi-functional device. The thermoelectric layer inside the device enables thermally cloaking in the IR spectrum by controlling the outer surface temperature as surrounding accurately by cooling and heating. This temperature variation is also adjustable to control the thermochromic layer on the outer surface of the device to produce various colors, which enables to expand the cloaking range of the visible spectrum and ultimately it provides a day-and-night stealth platform in a single device by simply controlling the temperature. Besides, independently composed scalable pixels of the device enable blending with background with a sophisticated pattern of higher resolution by localized control of each pixel and eventually enhancing the level of imperceptibility. As a proof-of-concept, human skin can be concealed in the multispectral regime by the skin-like single device as in nature, our work is expected to contribute to the development of next-generation covert military wearable suits and to improve multispectral cloak that includes invisible gadgets in the science fiction movies.두족류는 가장 많은 위장술을 갖고 있는 생물 중 하나로서, 여러가지 기능을 동시에 수행할 수 있는 독특한 능력을 가지고 있어 이를 모방하기 위한 많은 연구가 진행되고 있다. 특히 가시광선과 적외선(IR) 스펙트럼 모두에서 빠른 속도로 능동적으로 배경을 모사할 수 있는데, 온도를 조절하고 동시에 색감을 표현하는 데에 있어 기술적 난제로 남아 있다. 본 연구에서는 하나의 장치로 간단한 온도제어만으로 가시광선부터 IR 스펙트럼까지 주변 환경을 능동적으로 모사할 수 있는 이중 기능 장치를 웨어러블(wearable)한 인공 피부의 형태로 세계 최초로 제작하였다. 펠티어 효과를 이용하여 전류 방향을 통해 냉각과 가열을 조절하면서 외표면 온도를 정확하게 제어하여 IR 스펙트럼에서 열적인 위장을 가능하게 하였다. 이 온도변화는 장치 외표면의 온도 변색 영역에도 작용하여 다양한 색상을 생성하고 제어하는 것을 가능하게 하여 가시광선 스펙트럼 영역까지의 모방의 범위를 확장하였다. 독립적으로 제어될 수 있도록 구성된 픽셀들은 고해상도의 정교한 패턴을 구현하며 장치를 통해 위장 가능한 수준을 한단계 높였다. 즉 하나의 장치로 다중 스펙트럼 내 위장이 가능 한, 웨어러블 장치로서 주-야간 스텔스 기술을 완성하였으며, 이 결과는 차세대 위장 군복 개발 및 다중 스펙트럼 스텔스 기술에 기여할 수 있을 것이다.Chapter 1. Introduction 8 1.1 Study Background 8 1.2 Previous Researches 10 1.3 Objective and Overview of This Study 13 Chapter 2. Preparation and Method 17 2.1 Material Preparation 17 2.2 Fabrication Process 20 2.3 Measurement and Analysis 23 Chapter 3. System Design and Optimization 26 3.1 Schematic and Operating Mechanism 26 3.2 Thermoelectric Semiconductor 28 3.3 Optimizing the Design Parameters of Thermoelectric Pellets 29 3.4 Highly Thermally Conductive Elastomer 32 Chapter 4. Characterization and Performance Evaluation of the Device 41 4.1 Active mode for Accurate Thermal Control 41 4.2 Mechanical Reliability of the Device against Various Stress 49 4.3 Visualization Expression Based on CIE1931 51 Chapter 5. Thermally Controlled Camouflageable Device 54 5.1 Contribution of Thermal Pixels 54 5.2 Multispectral Cloaking Performance 55 5.3 Active Camouflage Artificial Skin 59 Chapter 6. Conclusions 62 References 63 Abstract (Korean) 67박

スマートフォンを用いて近距離からディスプレイとポインティング連携するための不可視ARマーカ

学位の種別: 修士University of Tokyo(東京大学

Watermarking of HDR images in the spatial domain with HVS-imperceptibility

This paper presents a watermarking method in the spatial domain with HVS-imperceptibility for High Dynamic Range (HDR) images. The proposed method combines the content readability afforded by invisible watermarking with the visual ownership identification afforded by visible watermarking. The HVS-imperceptibility is guaranteed thanks to a Luma Variation Tolerance (LVT) curve, which is associated with the transfer function (TF) used for HDR encoding and provides the information needed to embed an imperceptible watermark in the spatial domain. The LVT curve is based on the inaccuracies between the non-linear digital representation of the linear luminance acquired by an HDR sensor and the brightness perceived by the Human Visual System (HVS) from the linear luminance displayed on an HDR screen. The embedded watermarks remain imperceptible to the HVS as long as the TF is not altered or the normal calibration and colorimetry conditions of the HDR screen remain unchanged. Extensive qualitative and quantitative evaluations on several HDR images encoded by two widely-used TFs confirm the strong HVSimperceptibility capabilities of the method, as well as the robustness of the embedded watermarks to tone mapping, lossy compression, and common signal processing operations

Optical and Digital Technique for Watermark Detection

A digital watermark is a visible, or preferably invisible, identification code that is permanently embedded in some digital data to prove owner authentication and provide protection of that document. In this paper we utilize a watermark generation technique based on the use of chaotic functions and the motivation for using these functions is presented. The technique used for watermark embedding is also described, together with a watermark detection scheme based on an optical Matched Filter correlator. We provide results of optical simulations of the watermark detection scheme and show that correlation-based detection is an excellent method for detecting chaotically-generated watermarks embedded in the Fourier domain using multiplicative embedding.We also show that it is possible to detect chaotically-generated watermarks in images that have been subjected to noise

Optical and Digital Technique for Watermark Detection

A digital watermark is a visible, or preferably invisible, identification code that is permanently embedded in some digital data to prove owner authentication and provide protection of that document. In this paper we utilize a watermark generation technique based on the use of chaotic functions and the motivation for using these functions is presented. The technique used for watermark embedding is also described, together with a watermark detection scheme based on an optical Matched Filter correlator. We provide results of optical simulations of the watermark detection scheme and show that correlation-based detection is an excellent method for detecting chaotically-generated watermarks embedded in the Fourier domain using multiplicative embedding.We also show that it is possible to detect chaotically-generated watermarks in images that have been subjected to noise

On Dust:Memory as Performance and Materiality

The world\u27s worldliness is, to a large extent, perceptually constructed through touch, kinaesthetics, and proprioception. Gesture, too, is embedded in sedimentations of the body\u27s prior sensory exchanges with the environment. Materiality is transitive; it triggers sensory landscapes through performance. Consisting of particles of pollen, human and animal skin, hairs, minerals, soil, and burnt meteorites, dust is usually seen as the antithesis of the performative-material nexus. In this paper, I propose a different view: that dust is and acts as a connective tissue. Borrowing from Hélène Cixous\u27s écriture blanche, Quentin Smith\u27s degree presentism, and theorizing nostalgia as a structuring absence, I argue that dust does not numb memory but instead codes it. Activated by embodied acts that bring to light its metaphysical function, dust illuminates the grammar of existence in the spatial, temporal, and affective register

A Queer Politics of Imperceptibility: A Philosophy of Resistance to Contemporary Sexual Surveillance

This thesis journeys through a series of events to develop a concept of “imperceptibility” as a mode of resistance to contemporary sexual surveillance. The events I examine include biometric recognition of gender and race at airport security checkpoints, the heteropatriarchal colonial surveillance of Indigenous peoples at Standing Rock, various protest actions, and the political potentials of glitch art. Exploring their unexpected points of connection, my goal is to bring into view acts of resistance against sexual surveillance that already operate below and above the threshold of everyday perception. The project advocates for a philosophy of resistance that underscores the political importance of creating new modes of existence. Rather than engaging in the problematic of devising a new model of subjectivity, I argue that what is needed to escape from contemporary systems of capture and control is to turn from the Self as the primary site of concern and affirm instead the potentials of becoming-imperceptible. Imperceptibility signals not invisibility, but the act of relinquishing identity in favour of moving toward becoming everybody/everything. Far from a homogenizing or unitary endeavour, I propose imperceptibility as a radical celebration of difference that surges a revolutionary desire for social transformation through interconnectedness. Activating Gilles Deleuze and Félix Guattari’s pragmatic philosophy and style of writing, which emphasize multiple relations over binary oppositions, I introduce “a queer politics of imperceptibility” as a conceptual framework that takes a both/and approach to consider resistance. That is, I work with and between the tensions of feminist theories of recognition and Deleuze and Guattari’s nonrepresentational philosophy. I develop this framework in each chapter by mapping a constellation of interacting forces and affective intensities between bodies, both human and non-human. A Queer Politics of Imperceptibility makes an important intervention into the fields of feminist surveillance studies, posthumanism, affect theory, postcolonial theory and queer theory by revealing the ways in which imperceptible relations of resistance cascade into the political to generate new potentials to act in the world

Detection of human vital signs in hazardous environments by means of video magnification

In cases of natural disasters, epidemics or even in dangerous situations like an act of terrorism, battle fields, a shooting or a mountain accident, finding survivors is a challenge. In these kind of situations it is sometimes critical to know if a person has vital signs or not, without the need to be in contact with the victim, thus avoiding jeopardizing the lives of the rescue workers. In this work, we propose the use of video magnification techniques to detect small movements in human bodies due to breathing that are invisible to the naked eye. Two different video magnification techniques, intensity-based and phase-based, were tested. The utility of these techniques to detect people who are alive but injured in risk situations was verified by simulating a scene with three people involved in an accident. Several factors such as camera stability, distance to the object, light conditions, magnification factor or computing time were analyzed. The results obtained were quite positive for both techniques, intensity-based method proving more adequate if the interest is in almost instant results whereas the phase-based method is more appropriate if processing time is not so relevant but the degree of magnification without excessive image noise