<제 1 세부>
<제 2 세부>
구 분 제 목 주 요 내 용 비고
H/W 레이더 시스템
-소형무인이동체를 탐지할 수 있는 레퍼런스 레이더 시스템
-TX/Rx 패치안테나
H/W 레이더 RF 송수신 핵심 IP 칩
-레이더 RF Tx Phase shfiter+DA -FMCW Gen.
-레이더 RF Rx Core + BBA
HW 레이더 신호처리
HW 플랫폼
-RF 송수신기에서 받은 레이더 신호를 ADC보드에서 검출하여 GPU를 이용한 실시간 신호처리 SW 알고리즘을 구현하고 GUI를 통해 탐지된 레이더 신호를 디스플레이할 수 있는 신호처리 플랫폼 -RF 송수신기 빔제어 기능 수행
SW 레이더 신호처리
SW/HW 플랫폼
-CUDA기반 실시간 레이더 신호처리 SW 알고리즘
구 분 제 목 주 요 내 용 비고
H/W MIT 단독형 정온식 감지기
CTS 소자를 이용한 초 저전력 정온식 단독형 감지기
H/W MIT 연기 감지기 MPU 절전형 전원용 전기적 점프 소자 이용 전압 강하 파워를 이용한 연기 감지기
나. 전시/홍보
<제 1 세부>
● Sensors Expo 2018 (USA, San Jose, 2018. 06. 26 ~ 06. 28.)
- Critical Temperatuare Switch(CTS), Thermistor, Visible-UV Sensor 전시 및 기술 홍보
- SHIHENG GROUP, Western Human Nutrition Research Center, Bright Line Research 기업과 미팅
● 국제학술대회 발표 3건 (APS Physics march meeting)
- Decoupling of IMT and SPT for Mott Transition in Strained VO2 Films on AlN/Si(조진철, 테티아나, 김현탁)
- Time-Resolved Near-Field investigation of the Insulator to Metal transition in Vanadium Dioxide(김현탁, Dimitri Basov)
- Analysis of diverging effective mass near quantum critical point of x=0.3 in BaFe2(As1-xPx)2 (김현탁)
● MIT 연구, Internet으로 국제적으로 홍보 “Quora”: 클릭수 증가하고 있음 [Hyun-Tak Kim – Quora] https://www.quora.com/profile/Hyun-Tak-Kim (1) What is the paradox of superconductivity? 2018년 5월 28일
(2) What is a difference in ARPES spectra without and with the ... 2018년 2월 8일
(3) Why is the superconducting node gap observed in ARPES spectra of ... 2018년 1월 20일 (4) How do Fermi arcs form in superconductors? 2017년 12월 5일
l 인터넷 Q&A “Quora”에서 작성자가 답한 내용 중에서 중요한 것을 발췌(18.11.18 기준)
1. Why is the superconducting node gap observed in ARPES spectra of cuprate
superconductors? What is its physical meaning?
Hyun-Tak Kim, Project Leader at ETRI (1998-present)
Answered Jan 20, 2018Since the discovery of the high-T_c cuprate superconductor in 1986, many researchers have tried to reveal the high-T_c mechanism. Over the past 30 years, they have developed an explanation for the high T_c, deducing that the large energy gap at the antinode in angle-resolved photoemission spectroscopy (ARPES) spectra is the true superconducting gap because the energy gap is
proportional to the T_c. The magnitude of the superconducting antinode gap is much greater than that predicted in BCS theory. Accordingly, a new superconductor theory was required to explain the
SW 레이더 신호 GUI -실시간 레이더 신호 디스플레이하는 GUI
First, we define the d-wave pairing symmetry as having superconducting gaps at antinodes and no [Sassa Yasumine’s Ph. D paper, http://doc.rero.ch/record/200236...]. The superconducting node gap is obviously exhibited, and no gap is displayed at the antinode. This agrees with the explanation in
Furthermore, we mention that the energy gap at the antinode existed over T_cfor an underdoped formula of the superconducting transition temperature was given as T_c=1.14E_Dexp(-1/N(0)V), where E_D is the Debye cut-off energy, N(0) is the electronic density of states at the Fermi energy, V is the coupling potential of electron-phonon interaction. Superconductivity in
inhomogeneous cuprates appears in the two dimensional CuO_2 plane. The density of states in a two dimensional system is proportional to effective mass. In the cuprate systems, the effective mass diverges near the insulator-to-metal transition (IMT). A large effective mass near the diverging point can increase T_c in the BCS formula. Actually, the effective mass was largely measured over 4 times of band mass. The effective mass increases, when electron-electron Coulomb interaction in a metal is large (Brinkman-Rice picture). Accordingly, the Coulomb interaction can be a cause of high-T_c even in the electron-phonon interaction [effective mass]. The cuprate high-T_c materials have been known as strongly correlated materials.
Moreover, the coupling constant of b=2(gap)_{node}/k_BT_c has a value near the BCS criterion (3.5) or a little bit high value, because the superconducting intrinsic gap is the nodal
superconducting small gap [Intrinsic superconducting gap; node gap]. Many researchers have
believed that the pairing symmetry of the inhomogeneous cuprate superconductors is d_{x2-y2}-wave with an electronic structure of clover, and that the superconducting intrinsic true gap exists at the antinode without the nodal superconducting gap. Experimental results have not proved the d-wave
pseudogap phase with d_{x2-y2}-wave pairing symmetry. As doping is given near the insulator-metal transition (IMT) in the underdoped samples, the IMT occurs at node; this is called the d-wave IMT [Intrinsic superconducting gap (see line 16 to 15 from bottom at right column in page 2 in the paper); node gap]. Then, free carriers are produced at the nodes and form the superconducting gap at node; researchers who believe d-wave symmetry think that the nodal carriers remain
un-superconducting-gaped or carriers below T_c. Whereas, the superconducting antinode gap is not formed, because antinode has no carriers due to absence of the IMT at the antinode. The
superconducting gap is first formed at node and develops to antinode with increasing doping.
Finally, the superconducting gap becomes the s-wave gap like ring in the optimally or overdoped regime. Therefore, the cuprate superconductors has s-wave symmetry. This was already
experimentally corroborated.
In conclusion, the inhomogeneous cuprate superconductors are composed of the d-wave pseudogap phase and the metal phase in the normal state. The pseudogap with d-wave symmetry undergoes the IMT with doping and the metallic phase becomes the s-wave superconductor below T_c. The high
T_c is explained in the context of BCS theory by increase of two dimensional density of states
regarded as effective mass expressed by on-site Coulomb interation. The most important concepts are both the d-wave IMT and the forming mechanism of the nodal superconducting gap.Furthermore, the public relation on this question was given in internet questions
“How-do-Fermi-arcs-form-in-superconductors” and
“Why-is-the-superconducting-node-gap-observed-in-ARPES-spectra-of-cuprate-superconductors-What-is-its -physical-meaning”. Finally, a secret of high-T_csuperconductivity has already been revealed. Thank you for attention. May 12, 2018.
370 Views · View Upvoters
3. What is the paradox of superconductivity?
Hyun-Tak Kim, Project Leader at ETRI (1998-present)
, 2018Paradox!! For the mechanism of high-T_c superconductivity, I think “the observation of
superconducting node gap in cuprate high-T_c superconductors” is a paradox.Since the discovery of a high-T_c cuprate superconductor with over T_c=30 K in 1986, many scientists have challenged to reveal the mechanism of the high T_cover 30 years. Research papers over 200,000 have been published. The mechanism is still hot topic in condensed matter physics.
The d-wave pairing symmetry was introduced in weak-interaction calculations of an
antiferromagnetic spin fluctuation mediated pairing on the CuO_2 pane with Cu^{2+} in order to
explain the high-T_c mechanism. The calculations obtained T_c of 90 K on assuming that pairing
symmetry of superconductor’s carrier is d_{x^2-y^2} wave (d-wave). The d-wave pairing symmetry
is defined that superconducting gaps exist at antinodes without gap at nodes in k-space and changes phase between antinodes, which is unconventional pairing symmetry comparing to s-wave pairingsymmetry. Experiments such as ARPES, electronic Raman scattering, tunnel effect, phase sensitive
experiments, penetration depth, specific heat etc, have proved d-wave symmetry. Therefore, most
researchers have believed that the pairing symmetry is d-wave. However, the ARPES and electronic
Raman experiments showing d-wave evidence also observe a nodal superconducting gap shaking the
foundation of the d-wave pairing symmetry. That is, the observation of the nodal gap is to deny
d-wave symmetry. Moreover, it was analyzed that the intrinsic superconducting gap exists at node not antinode.When the nodal superconducting gap of the paradox is identified, the high-T_cmechanism would be resolved. May 26, 2018
127 Views
4. What is a difference in ARPES spectra without and with the superconducting node gap for high-TCcuprate superconductors?
Hyun-Tak Kim, Project Leader at ETRI (1998-present)
, 2018believe that the pairing symmetry is d-wave based on experimental results, although experimental consequences denying d-wave symmetry have also been published. Revealing the pairing symmetry for the high-T_c mechanism is still a vital central issue.
This question compares two kinds of ARPES (angle resolved photoemission spectroscopy) spectra.
One is the well-known spectrum as evidence of d-wave pairing symmetry (Fig. 1(c)) [Z. X. Shen et
al., Phys Rev Lett 70, 1553 (1993)], but the other is a spectrum measured in a high resolutionARPES system (Fig. 1(d)) [A. Kaminski et al., Phys. Rev. Lett. 84, 1788 (2000)]. Fig. 1(c) shows an anomalous gap anisotropy with a large superconducting gap at the antinode and a small
superconducting gap at the node measured in an underdoped inhomogeneous BSCCO crystal using
ARPES. The important result is that the shape of spectra below and above T_c at the node B is
Hyun-Tak Kim, Ph.D., Prof., Principal Researcher at ETRI
Updated Dec 5, 2017The question pertains to the high-Tc mechanism in inhomogeneous layered cuprate superconductors.
To identify this mechanism, the cause of the formation of Fermi arcs, which emerge in underdoped crystals with a pseudogap, must be understood; the pseudogap is an energy gap of the
non-superconducting phase in the inhomogeneous superconductors. As mentioned by Prof. Inna Vishik in the first answer to the question, the cause is one of the high-Tc mysteries and has puzzled researchers in the past. However, it is noted that the formation of the Fermi arcs can be explained with a d-wave metal-insulator transition (MIT) or insulator-metal transition (IMT) [1,2,3,4].
The MIT occurs because the pseudogap at the nodes in k-space disappears and the maximum and constant number of carriers appear at the nodal Fermi point (Figure 1). The MIT results from the evolution of the pseudogap with dx2-y2-wave symmetry. As doping increases, the MIT continuously occurs from node to antinode following the d-wave MIT, which takes place at node. The Fermi surface develops from the Fermi point to the Fermi ring through the Fermi arc. This is the mechanism by which the Fermi arcs form.
Figure 1. The d-wave-MIT. Energy-distribution images measured by ARPES (angle resolved
photoemission spectroscopy) for underdoped non-superconducting YBa2Cu3COy crystals. The crystal of y=6.25 has a pseudogap of approximately 0.1 eV (white arrow) at the nodes and the crystal of y=6.40 has carriers at EF (the zero value in Figure); this is the d-wave MIT. This is cited as Y.
Hajime, Ph.D paper, 2005,
Photoemission study of the high-temperature superconductor YBa2Cu3Oy.Furthermore, the carriers induced by the d-wave MIT at node contribute to the formation of a superconducting node gap below Tc, which has been experimentally observed and identified as the intrinsic superconducting gap [1,4] (Figure 2). This is not explained in terms of the previously accepted d-wave concept, in which the superconducting carriers have dx2-y2-wave pairing symmetry that has the superconducting gap at antinode but no gap at node. To emphasize, the pseudogap has
d-wave symmetry while the superconducting gap has s-wave symmetry [1,4].
Figure 2. The d-wave MIT and the superconducting node gap. (a) The hump (pseudogap) of red Investigations on in situ PLD grown YBa2Cu3O7-d.
As for the pairing mechanism, since the magnitude of the superconducting node gap Gap_{node} is small and Tc is large, the coupling constant (b=2Gap/k_BT_c) has a value of about 4 [1,4]. Thus, the pairing mechanism of the superconducting carriers can be explained within the context of BCS theory (in which the electrons in the Cooper pair are coupled by phonons). In the case of
dx2-y2-wave pairing, the large coupling constant, b, obtained using the large superconducting
antinode gap Gap_{antinode}, remarkably deviates from the limit of the BCS theory, which means that a new d-wave model, not the phonon-coupling mechanism, had to be developed; Figure 2c does not show Gap_{antinode}. However, observations of the intrinsic superconducting node gap (Figure 2) make the d-wave superconducting gap model unnecessary. Furthermore, the high Tc mustbe caused by a large two-dimensional density of states which is proportional to the effective mass [4].
91 Views (400 회이상에서 데이터가 지워졌고, 다시 올라오고 있는 것임, 실제는 500 회 이상임)
<제 2 세부>
내용 홍보
○IEEE Radio Frequency Integrated Circuit symposium in USA 전시/홍보 (2018.6.11.)
<RFIC 전시홍보>
○포항공대 미래전자파응용워크샵:국방과ICT응용, 발표홍보
(2018.11.15.)
<워크샵 발표홍보>
제 4 장 결론 및 연구결과의 활용계획
제 1 절 결론
○ MIT 기술 (제1세부)
- MIT 현상규명 연구는 물리학의 문제로서 본 연구실이 개발한 Hole-driven (Impurity-induced) MIT 이론 기반으로 측정된 YBCO 물질에서 d-Wave MIT를 발견하고 성공적으로 논문을 만들고 30년 이상의 물리문제를 풀어내고 성과확산을 위해 노력하였음. 또한 국제공동연구를 통해 보 다 나노급 초고속시스템으로 MIT를 측정하여 구조 상전이 없는 MIT를 관측하여 연구를 확산시 켰음. 그 결과 논문 인용이 계속 늘어나서 MIT 논문 전체 인용이 7000편에 육박하고, 본 연구 팀이 국제적으로 유명한 팀으로 부상하게 되었음. 그에 따라 한국 및 ETRI의 명성도 함께 올 라가는 쾌거를 거두고 있음.
- MIT 응용연구는 MIT 메커니즘 기반에서 제조된 MIT 소자가 만들어지고 판매됨으로서 실질적으 로 연구가 확산되고 있음. MIT 스위칭으로 DC-DC 컨버터에서 Full-wave 방식의 스위칭 특성을 세계최초로 발명하기도 하였음. 그리고 후속으로 부가가치가 큰 시스템으로 연기감지기 단독 형 감지기가 만들어 졌고, 또 MIT 재료 기반의 조도센서, 인체온도 감지용 적외선 센서가 만 들어 져서 해외 전시를 통해 성과 확산에 노력을 기술이고 있음. 추가로 기존 방식과 다른 전 자파 측정방식으로 전류센서를 만드는 부수적 연구결과를 얻었음. 따라서 그 결과 국내 산업 화에 이바지할 것으로 예상
○ 소형무인이동체 탐지레이더 (제2세부)
- RCS = 0.01m2의 소형드론과 같은 소형무인이동체를 탐지할 수 있는 레이더의 핵심부품 원천기 술 확보와 시스템 국산화를 추구하며 레이더 규격 및 구조를 확립 함
- FMCW 방식으로 거리해상도와 움직임 탐지를 효과적으로 수행하며, 1m 단위 해상도로 탐지할 수 있고, 방위각 90도 와 고도각 45도를 스캔하면서 최대 1.5km반경을 커버할 수 있는 탐지레 이더 시스템 구조를 설계 하였음
- 1차년도 결과물로서 상용부품들을 활용한 안테나를 비롯한 RF 프론트엔드단의 레퍼런스 레이 다 시스템을 구축하고 과제 목표치인 500m이상 거리의 드론을 탐지하는 성과를 확인 함
- 레퍼런스 레이더 시스템의 RF송수신 상용 개별 부품들을 RF 송수신 IP 설계하여 원천기술을 확보 하였음
- 1km 범위의 소형무인이동체를 탐지할 수 있는 신호처리 SW 알고리즘을 구현하였으며, 실시간 동작시키기 위하여 GPU 병렬처리 프로세서를 활용한 실시간 CUDA 알고리즘을 구현하고, 상용 ADC보드와 연결하여 PC기반의 신호처리플랫폼 보드 개발 함
- 테스트 결과를 디스플레이 할 수 있는 신호처리 GUI를 개발하였음
- 1차년도 개발 연구목표를 초과 달성하였으며, 정량적인 SCI논문 1건제출 및 일반논문 2건 발 표하고, 국내/국제 특허 출원 및 제출 포함하여 총7건을 달성함
제 2 절 파급효과 및 성과확산계획
1. 파급효과미래유망 연구분야 선점 가능성
○ 선구적인 MIT 연구로 이론 및 물리문제 해결로 국위 선양
○ MIT 센서는 열, 빛, 전기 분야 시스템의 크기를 획기적으로 줄이고, 성능이 기존 대비 훨씬 뛰어 나서 새로운 패러다임을 전환할 예정임
○ MIT 스위칭은 반도체 스위칭보다 발열이 작아서 보다 작은 파워서플 라이가 가능하여 기존 기술 의 한계를 극복하는 기술임
○ 드론 및 소형무인이동체는 크기가 작고 저고도로 비행하여 레이더에 잘 포착되지 않기 때문에, 드론 이 보급되면서 생기는 문제점 발생 - 대표적인 것이 사생활 침해, 산업 기밀 유출, 폭발물 탑재 테러 위협 등에 쉽게 노출됨에 따라 드론 비행을 규제하려는 움직임은 전 세계적인 현상이므로, 기술 개발 완료시 미래시장 선점 가능성이 큼
연구목표 달성 시 활용분야 파급성
○ MIT-양자 기술은 신개념으로 응용분야가 뉴로모픽 방향으로 확산되고 있어서 목표기술 확보시 정부 수탁이 가능할 것으로 예상함
○ 레이더 기술은 군/민간용 공중감시 시스템 구성에 필요한 저고도, 중저속 물체 탐색 및 추적에 사용 하여 드론을 이용한 적의 공격 및 정찰을 격퇴하고, 불특정 다수를 노리는 테러 방지, 중요 시설물 보안 시스템에 활용
2. 성과확산계획
2. 성과확산계획