20 research outputs found
Graphene based flexible strain sensor for wearable device
ํ์๋
ผ๋ฌธ (์์ฌ)-- ์์ธ๋ํ๊ต ๋ํ์ : ๊ณต๊ณผ๋ํ ๊ธฐ๊ณํญ๊ณต๊ณตํ๋ถ, 2019. 2. ์ด์ ํ.์ต๊ทผ ๋ก๋ณดํฑ์ค์ ์จ์ด๋ฌ๋ธ ๊ธฐ๊ธฐ, ํฌ์ค์ผ์ด ๊ด๋ จ ๋ถ์ผ์์์ ๋์ ํ์ฉ ๊ฐ๋ฅ์ฑ์ผ๋ก ์ธํด ๋ณํ๋ฅ ์ผ์ ์ฐ๊ตฌ๊ฐ ํ๋ฐํ ์ด๋ฃจ์ด์ง๊ณ ์๋ค. ๋๋
ธ์์ด์ด, ๋๋
ธ ์
์, ํ์๋๋
ธํ๋ธ ๋ฐ ๊ทธ๋ํ์ ๋น๋กฏํ ๋ค์ํ ์์ฌ๋ก ์ ์ฐํ๊ณ ๋ฏผ๊ฐํ ๋ณํ๋ฅ ์ผ์์ ๋ํ ์ฐ๊ตฌ๊ฐ ์งํ๋๊ณ ์๋ค. ๊ทธ ์ค์์๋ ๊ทธ๋ํ์ ๋์ ์ ๋์ฑ, ์ ์ฐ์ฑ ๋ฐ ๊ธฐ๊ณ์ ๊ฐ๋๋ก ์ธํด ๋ง์ ์ฃผ๋ชฉ์ ๋ฐ๊ณ ์๋ค. ๋ณธ ์ฐ๊ตฌ์์๋ ๊ทธ๋ํ ๊ธฐ๋ฐ ์ ์ฐํ ๋ณํ๋ฅ ์ผ์์ ์นํ๊ฒฝ์ ๊ณต์ ๋ฐ ํจํฐ๋ ๋ฐฉ๋ฒ์ ๋ํด ๋ค๋ฃฌ๋ค. ๊ทธ๋ฆฌ๊ณ ์ ์๋ ์ผ์๋ฅผ ์ด์ฉํ์ฌ ๋ฌผ์ฒด์์ ๊ฑฐ๋ฆฌ๋ฅผ ์ธ์ํ๊ณ ๋ฌผ์ฒด์ ํ๋ฉด ํ์์ ์ฌ๊ตฌ์ฑํ๋ ์คํ์ ์ํํ์๋ค.Recently, strain sensors have been actively studied due to their high utilization potential in robotics, wearable devices, and health care related fields. Many researchers are working on a variety of materials including nanowires, nanoparticles, carbon nanotubes(CNTs), and graphenes to fabricate these flexible and sensitive strain sensors. Among them, graphene is attracting much attention due to its high conductivity, flexibility and mechanical strength. In this study, we tried to maximize the advantages of graphene - based strain sensor by studying human - friendly manufacturing method and easy patterning process. Experiments were carried out to recognize the distances to objects and to reconstruct the shapes of the objects by analyzing the signals using the produced graphene - based strain sensors.๊ตญ๋ฌธ์ด๋ก i
๋ชฉ์ฐจ ii
๊ทธ๋ฆผ ๋ชฉ์ฐจ iii
์ 1 ์ฅ ์๋ก 1
์ 1 ์ ์ฐ๊ตฌ๋ฐฐ๊ฒฝ 1
์ 2 ์ ์๋ ์๋ฆฌ 5
์ 2 ์ฅ Graphene coating 7
์ 1 ์ Stencil method 7
์ 2 ์ Layer by Layer coating method 12
์ 1 ์ Inkjet printing method 14
์ 3 ์ฅ Reduction process 19
์ 1 ์ Flash reduction 19
์ 2 ์ Chemical reduction 20
์ 4 ์ฅ Discussion 21
์ 1 ์ Fabrication protocol 21
์ 2 ์ Result 23
์ 5 ์ฅ Conclusion 26
์ฐธ๊ณ ๋ฌธํ 27
Abstract 29Maste
Effects of low temperature deuterium annealing on electrical properties at SiSiOโ interface
ํ์๋
ผ๋ฌธ(์์ฌ) --์์ธ๋ํ๊ต ๋ํ์ :์ ๊ธฐ. ์ปดํจํฐ๊ณตํ๋ถ,2007.Maste
Antitumor efficacy of hypoxia and alpha-fetoprotein-dependent oncolytic adenovirus and systemically injectable adenovirus-liposome hybrid vector
์๊ณผํ๊ณผ/๋ฐ์ฌ์ข
์ ์ ํ์ ์ด์ adenovirus(Ad) ๋ ๊ธฐ์กด์ ๋ณต์ ๋ถ๋ฅ Ad๋ณด๋ค ์น๋ฃ ํจ๊ณผ ๋ฐ ์ ์ ์ ์ ๋ฌํจ์จ์ด ๋๊ฒ ๋ํ๋จ์ ๋ฐ๋ผ ์ ์ ์ ์ ์น๋ฃ์ ์๋ก์ด ์น๋ฃ์ ๋ก ์ฐ๊ตฌ๊ฐ ํ๋ฐํ ์งํ ์ค์ด๋ค. ์ด์ ๋ฐ๋ผ, ๋ณธ ์คํ์ค์์๋ E1B19 kDa ์ด ์ ๊ฑฐ๋ ์ด์ Ad(Ad-โE1B19)๋ฅผ ๊ฐ๋ฐํ์ฌ ๊ฐ๋ ฅํ ์ธํฌ ์ด์ํจ๊ณผ๋ฅผ ๋ณด๊ณ ํ ๋ฐ ์๋ค. ํ์ง๋ง, Ad-โE1B19๋ ์์ธํฌ๋ฟ ๋ง ์๋๋ผ ์ ์์ธํฌ๊น์ง ์ด์ํ๋ ํ๊ณ๊ฐ ๋๋ฌ๋ฌ๋ค. ๋ฐ๋ผ์ ๋ณธ ์ฐ๊ตฌ์์๋ ๊ฐ์ ์ธํฌ ํน์ด์ ์ธ ์ธํฌ ์ด์ ํจ๊ณผ๋ฅผ ํ๋ํ๊ธฐ ์ํด ํฅ์๋ human alpha-fetoprotein (hAFP) promoter๋ฅผ Ad์ ๋ณต์ ๋ฅผ ์กฐ์ ํ๋๋ฐ ์ฌ์ฉํ์๋ค. ๋ํ ์ข
์ ๋ด์ ์ ์ฐ์ ํ๊ฒฝ์์ promoter์ ํ์ฑ์ ์ฆ๊ฐ์ํค๊ธฐ ์ํด 6 ๋๋ 12 copies์ hypoxia response element(HRE)๋ฅผ ์ฝ์
ํ์ฌ hAFP promoter ๋๋ HREs/hAFP ์ ์ํด E1A ๋ฐํ์ด ์กฐ์ ๋๋ ์ข
์ ์ ํ์ ์ด์ Ad๋ฅผ ์ ์ํ์๋ค. HRE12๊ฐ ์ฝ์
๋ Ad-HRE12/hAFPโ19๋ ๋์กฐ๊ตฐ์ธ Ad-hAFPโ19๊ณผ ๋น๊ตํ์ฌ ํฅ์๋ ์ข
์ ์ ํ์ฑ๊ณผ ์ธํฌ ์ด์๋ฅ์ ๋ํ๋๋ค. ๋น์นจ์ต์ฑ ๋ถ์ ์์์ผ๋ก Ad-HRE12/hAFPโ19์ ์ข
์ ์ด์๋ฅ์ ๊ด์ฐฐํ์์ ๋ ํผํ๋ชจ๋ธ๊ณผ ์๋ฐ์ฑ ๊ฐ์ ๋ชจ๋ธ ๋ชจ๋์์ ์์ฒด ์ธ ๊ฒฐ๊ณผ์ ์ผ์นํ๊ฒ ์ฆ๋๋ ์ข
์ ์ ํ์ฑ๊ณผ ์ข
์ ์ฑ์ฅ ์ต์ ๋ฅ์ ๋ํ๋๋ค. ๋ํ, ์ข
์์ ์กฐ์งํ์ ์คํ์ ์งํํ์์ ๋ ์ ์ฐ์ ์ง์ญ์์ ๋ฐ์ด๋ฌ์ค์ ๋ณต์ ๊ฐ ํ๋ฐํ ์ผ์ด๋๋ ๊ฒ์ ํ์ธํ์๋ค. ์์ธ๋ฌ Ad-HRE12/hAFPโ19๋ฅผ ์ ๋งฅ์ฃผ์ฌ ํ ์์ฅ์์๋ ์ฌ๊ฐํ ๋ฉด์ญ๋ฐ์, ๊ฐ ๋
์ฑ ๋๋ ์กฐ์ง ๋
์ฑ์ด ๊ด์ฐฐ๋์ง ์์๋ค. ์ด๋ฌํ ๊ฒฐ๊ณผ๋ค์ ๋ฐํ์ผ๋ก ๋ณธ ์ฐ๊ตฌ์์๋ hAFP promoter์ HREs๊ฐ ์ฝ์
๋ Ad-โE1B19๋ ํฅ์ ๋ ๊ฐ์ ์กฐ์ง ํน์ด์ฑ๊ณผ ์ข
์ ํ๊ฒฝ ์ ํ์ฑ์ ๋ํ๋ด๋ ๊ฒ์ ๊ฒ์ฆํ์๋ค.
๋ฐ๋ผ์ ์ฆ๋๋ ์ ํ์ฑ๊ณผ ์ข
์ ์ด์๋ฅ์ ๊ฐ์ง Ad-HRE12/hAFPโ19๋ AFP๋ฅผ ๋ฐํํ๋ ๊ฐ์์ ํจ๊ณผ์ ์ธ ์น๋ฃ์ ๊ฐ ๋ ๊ฒ์ผ๋ก ์ฌ๋ฃ๋๋ค. ๊ทธ๋ฌ๋ ์๋ฐ์์ด๋ ์ ์ด์์ ์น๋ฃํ๊ธฐ ์ํ ๋ชฉ์ ์ผ๋ก ์ ๋งฅ ์ฃผ์ฌ๋ฅผ ํตํ Ad์ ์ ๋ฌ์ ์ฒด๋ด์ ์กด์ฌํ๋ Ad์ ๋ํ ํญ์ฒด์ ์ํด ์น๋ฃํจ๊ณผ๊ฐ ๋จ์ด์ง๋ค. ๋ฟ๋ง ์๋๋ผ ๊ฐ์ ๋ํ ๋์ ์นํ๋ ฅ์ผ๋ก ์ธํด ๊ฐ ์ด์ธ์ ์ํ๋ ์ ์กฐ์ง์๋ ์ ๋ฌ์ด ์ฉ์ดํ์ง ์์ ๋จ์ ์ ๊ฐ์ง๊ณ ์๋ค. ์ด๋ฌํ ์ ์ ๊ทน๋ณตํ๊ณ ์ ๋ณธ ์ฐ๊ตฌ์์๋ ๋น ๋ฐ์ด๋ฌ์ค์ฑ ๋ฒกํฐ์ธ liposome์ Ad์ DNA๋ฅผ ์ฝ์
ํ์ฌ hybrid ๋ฒกํฐ๋ฅผ ์ ์ํ์๋ค. ์ฌ์ฉ๋ DNA๋ HRE์ ๋ณํ๋ TERT promoter์ ์ํด E1A ๋จ๋ฐฑ์ง์ด ์กฐ์ ๋๊ณ , ๋ถ๋น๋๋ TRAIL ๋จ๋ฐฑ์ง์ ๋ฐํํจ์ผ๋ก์ ์์ธํฌ ์ด์๋ฅ๊ณผ ์ ํ์ฑ์ด ์ฆ๋ ๋ Ad DNA(H5mT-Rd19/stTR)์ด๋ฉฐ ํ์์ ํ์ ํ ํ๋ DOTAP :DOPE ๋๋ PEG:DOTAP:DOPE๋ฅผ liposome์ผ๋ก ์ด์ฉํ์ฌ Ad DNA์ liposome์ด 1:6์ ๋น์จ๋ก ํผํฉ๋ ์ฝ 150 nm์ size๋ฅผ ๊ฐ๋ hybrid ๋ฒกํฐ๋ฅผ ์ ์ํ์๋ค. Hybrid ๋ฒกํฐ๋ ํ์์ธํฌ์์ ์ ํ์ ์ธ ์ธํฌ ์ด์๋ฅ์ ๋ํ๋์ผ๋ฉฐ, ์์ฅ์ ์ ๋งฅ์ฃผ์ฌ ํ์์ ๋ ๋ฉด์ญ๋ฐ์๊ณผ ๊ฐ ๋
์ฑ์ ๊ด์ฐฐ๋์ง ์์๋ค. ์ด๋ฌํ ๊ฒฐ๊ณผ๋ฅผ ํตํด Ad DNA-liposome hybrid ๋ฒกํฐ๋ ๊ตญ์์ ์ธ ์ ์น๋ฃ๋ฟ ์๋๋ผ ์ ์ด ์์ ์น๋ฃ์ ๋ก์ ์ ์ฉํ๊ฒ ์ด์ฉ๋ ์ ์์ ๊ฒ์ผ๋ก ์ฌ๋ฃ๋๋ค.ope
๋ฏธ์ธ ๊ฐ๊ณต๋ ๋๋ฅ์ ์ ๊ธฐ๋ฐ ํ ๋ฅดํค๋ฅด์ธ ์ฅ์น์ ๋ํ ์คํ ์ฐ๊ตฌ
ํ์๋
ผ๋ฌธ(๋ฐ์ฌ)--์์ธ๋ํ๊ต ๋ํ์ :์์ฐ๊ณผํ๋ํ ๋ฌผ๋ฆฌยท์ฒ๋ฌธํ๋ถ,2016. 8. ๋ฐ๊ฑด์.For the last decade, terahertz waves have been the focus of many researches to lead to a diverse range of potential applications, such as bio-medical imaging systems, security inspection systems, material analysis systems, and high-data-rate communications systems. Though many types of terahertz components have been developed, e.g., terahertz antennas, filters, guides, and detectors, realistic terahertz applications remain rare due to the lack of powerful, efficient, practically sized, inexpensive, and stable terahertz sources which would fill the terahertz gap. While time-domain spectroscopy (TDS) systems are the main streams of terahertz sources due to the instant spectroscopic capabilities throughout the terahertz range, vacuum electronic devices (VEDs) have also garnered interest due to their high-power capabilities resulting from the high kinetic energy of their convection electrons.
In this dissertation, 0.1 THz coupled cavities backward wave oscillator (CCBWO) is proposed and studied as preliminary research on terahertz VEDs, applying two-step LIGA as well as ultra nano CNC machining. The circuits are fabricated with less tolerance than a micron and the cold measurements are in excellent agreement with numerical simulation. All other components of the 0.1THz CCBWO system such as 12kV, 50mA electron gun, 2800gauss of PPM, 8% of band center frequency transmitting vacuum window, and -9kV depressed collector are designed, fabricated, and experimented and all the results match strongly to the design. All parts are assembled together and with the bias voltage at beam focusing electrode, desired perveance is observed in the beam test.
0.22THz staggered extended interaction oscillator is also investigated, focusing on the strong interaction even with relatively low voltage. In the half ฯ phase shifted double grating resonator, The large fraction of the fundamental TE mode is longitudinally polarized, and it excites the intense plasma-terahertz wave coupling at the shallow grating, which enables highly efficient RF generation at a relatively low operating voltage. A particle-in-cell (PIC) simulation predicts that the half-period phase-staggered grating resonator generates 0.22 THz wave with output power exceeding 100 W and interaction efficiency of more than 15 % at a low beam acceleration voltage of 5.2 kV.Chapter 1 Introduction 1
1.1 Terahertz 1
1.1.1 THz gap 2
1.1.2 Present THz sources 4
1.2 Vacuum Electronic Devices (VEDs) 6
1.3 Terahertz VEDS and problems 10
1.4 Motivation and Goal 10
1.5 Outline 11
Bibliography 13
Chapter 2 Experimental study of 0.1THz Coupled Cavities Backward Wave Oscillator (CCBWO) 19
2.1 Introduction 19
2.2 0.1THz CCBWO circuit 20
2.2.1 Design of 0.1THz CCBWO circuit 20
2.2.2 Two step LIGA fabrication 35
2.2.3 Ultra-Nano machining 37
2.2.4 Cold test of 0.1THz CCBWO circuit 42
2.3 Electron gun 45
2.3.1 Design of electron gun 45
2.3.2 Fabrication of electron gun 50
2.3.3 Beam-emission test 56
2.4 Periodic Permanent Magnet (PPM) focusing 58
2.4.1 Design of PPM 60
2.4.2 Fabrication of PPM 63
2.4.3 Measurement of PPM 65
2.5 Wide band width anti-reflecting vacuum window 67
2.5.1 Transmission analysis of pillbox window 69
2.5.2 Design of broadband width of 0.1THz vacuum window 79
2.5.3 Cold test of 0.1THz vacuum window 83
2.6 Depressed collector 85
2.6.1 Design of depressed collector 86
2.6.2 Fabrication of depressed collector 88
2.7 System assembly of 0.1THz CCBWO 92
2.7.1 RF test of 0.1THz CCBWO 98
2.8 Conclusion 99
Bibliography 100
Chapter 3 Theoretical study on 0.22 THz sheet beam staggered Extended Interaction Oscillator (sEIO) 102
3.1 Introduction 102
3.2 Design of 0.22THz sEIO 103
3.2.1 sEIO โ Powerfully modified EIO 103
3.3 Particle-In-Cell (PIC) numerical hot test 108
3.4 Conclusion 119
Bibliography 120
Chapter 4 Conclusion 121
List of Publications 122
Domestic Conference proceedings and abstracts 128
๊ตญ๋ฌธ ์ด๋ก 130Docto
Design of a Fault Tolerant Multilayer Perceptron Neural Network Minimizing the Effect of Quantization
Docto
ํํ ์ ์ด๋ 2์ฃผ๊ธฐ ๋ฏธ๋ง ๊ด ํ์ค์ ์ํ ๊ณ ์ฒด ๋ฐ ๊ธฐ์ฒด ๋ด ์ ์ ์ญํ์ ๊ทน์ด๊ณ ์ ์ ์ด์ ๊ด์ธก
DoctorMeasurement and manipulation of electron dynamics is a flourishing area of research which catches attention nowadays. Fundamental phenomena, in which electrons are involved, such as electron transition between bands in condensed matter and energy states in atoms, mostly occur at femtosecond or sub-femtosecond time scale. The observation and control of electronsโ behavior has been facilitated owing to the utmost development of laser technology. In this thesis, one of the state-of-the-art light sources, waveform-controlled sub-2-cycle optical laser, was employed to explore the interaction with media in solid and gas phases.
In a study with solid media, semimetallization was observed in dielectric crystals subjected to strong laser field. A current was generated and directed by the instantaneous light field. A series of theoretical calculation, based on quadruple sub-band model, showing good agreement with experiment, implies that the semimetallization was brought about by electron transition between and within valence and conduction sub-bands. Semimetallization was observed to be a general response of dielectrics to intense light field. It is accounted for by Wannier-Stark localization, a confinement of electrons in a unit cell of crystal lattice under strong field; the effect of long range crystal structure becomes less important.
On the other hand, for a study with gaseous medium, an instrument for single-isolated attosecond pulse, which permits one to trace sub-femtosecond electron dynamics, was constructed. By means of high harmonics generation, a train of XUV attosecond pulses were produced and then underwent spectral filtering to select single XUV burst. The temporal profile of the XUV pulse was attained by analyzing the photoelectron kinetic energy spectrogram, ensuring the generation of a single-isolated attosecond pulse. The attosecond pulse was utilized to examine the AC Stark splitting of noble gas atom exposed to intense light field. The attosecond transient absorption spectroscopy was applied to xenon atoms exposed to an NIR intensity of ~1013W/cm2. The asymmetric AC Stark splitting (or, in other words, Autler-Townes splitting) and sub-cycle oscillation in absorption lines were revealed. Theoretical estimation relying on TDCIS, which was in accordance with experimental findings, asserted that the counter rotating wave effect is responsible for the observation
A cyclic RGD-coated peptide nanoribbon as a selective intracellular nanocarrier
We have synthesized a peptide-based supramolecular building block consisting of a cyclic Arg-Gly-Asp (cRGD) peptide segment and a beta-sheet-forming peptide segment. The block peptide was shown to self-assemble into a cRGD-coated nanoribbon structure, as revealed by circular dichroism (CD), dynamic light scattering (DLS), and transmission electron microscopy (TEM) studies. We have shown that this cRGD-coated nanoribbon can encapsulate hydrophobic guest molecules and deliver them into cells. Colocalization of the nanoribbon with LysoTracker and the selective intracellular delivery results suggests that the cRGD-coated nanoribbon is likely to be internalized into the cells through integrin receptors.ope
Ionically crosslinked Ad/chitosan nanocomplexes processed by electrospinning for targeted cancer gene therapy
For effective cancer gene therapy, systemic administration of tumor-targeting adenoviral (Ad) complexes is critical for delivery to both primary and metastatic lesions. Electrospinning was used to generate nanocomplexes of Ad, chitosan, poly(ethylene glycol) (PEG), and folic acid (FA) for effective FA receptor-expressing tumor-specific transduction. The chemical structure of the Ad/chitosan-PEG-FA nanocomplexes was characterized by NMR and FT-IR, and the diameter and surface charge were analyzed by dynamic light scattering and zeta potentiometry, respectively. The average size of Ad/chitosan-PEG-FA nanocomplexes was approximately 140 nm, and the surface charge was 2.1 mV compared to -4.9 mV for naked Ad. Electron microscopy showed well-dispersed, individual Ad nanocomplexes without aggregation or degradation. Ad/chitosan nanocomplexes retained biological activity without impairment of the transduction efficiency of naked Ad. The transduction efficiency of Ad/chitosan-PEG-FA was increased as a function of FA ratio in FA receptor-expressing KB cells, but not in FA receptor-negative U343 cells, demonstrating FA receptor-targeted viral transduction. In addition, the transduction efficiency of Ad/chitosan-PEG-FA was 57.2% higher than chitosan-encapsulated Ad (Ad/chitosan), showing the superiority of FA receptor-mediated endocytosis for viral transduction. The production of inflammatory cytokine, IL-6 from macrophages was significantly reduced by Ad/chitosan-PEG-FA nanocomplexes, implying the potential for use in systemic administration. These results clearly demonstrate that cancer cell-targeted viral transduction by Ad/chitosan-PEG-FA nanocomplexes can be used effectively for metastatic tumor treatment with reduced immune reaction against Ad.ope
Enhanced delivery of adenovirus, using proteoliposomes containing wildtype or V156K apolipoprotein A-I and dimyristoylphosphatidylcholine
The delivery of genes or viruses via liposomes is a common approach used to enhance delivery efficiency. In the current study, to enhance delivery efficiency, proteoliposomes (PLs) containing adenovirus (Ad) were synthesized with dimyristoylphosphatidylcholine (DMPC), cholesterol, and apolipoprotein A-I (apoA-I). Wildtype apoA-I (WT) or V156K-apoA-I (V156K) was then used as an apolipoprotein to compare the structural and functional differences of the PLs. The particle diameter of V156K-PL-Ad was slightly larger than that of WT-PL-Ad, based on native gel electrophoresis. V156K showed more rapid phospholipid bilayer formation than did the WT, based on DMPC clearance. In addition, V156K exhibited maximal fluorescence that was more blue than that of WT in the PL state. Moreover, isothermal denaturation in response to the addition of guanidine hydrochloride (Gnd-HCl) revealed that V156K was more resistant, with no denaturation until 3 M Gnd-HCl was added. In addition, electron microscopy revealed that the viral particles were well associated with PL particles, which had a discoidal structure and were shaped like rouleaux. In addition, treatment of Ad in the PL state showed enhanced green fluorescent protein (GFP) expression when compared with treatment with Ad alone or with DMPC-Ad in hepatoma and brain glioma cells. Cells treated with WT-PL-Ad and V156K-PL-Ad showed approximately 50% more GFP expression than cells treated with Ad alone or with DMPC-Ad after 24 hr of incubation at 37 degrees C, indicating that viral stability was highly increased in the PL state. Furthermore, V156K-PL-Ad showed the highest expression of GFP in adult zebrafish (9 weeks old) at 5 days postinjection (10.5- and 3.8-fold more GFP expressed than by Ad only and DMPC-Ad, respectively). In conclusion, the efficiency of viral delivery and the stability of the virus were significantly enhanced when PLs containing apoA-I were used in cellular and zebrafish models.ope