단일 전자 소자에서 에너지 준위간 전이율 계산

정해두,정해두 한국물리학회 2006 새물리 Vol.52 No.6

The order of the relaxation time of electrons in a quantum dot within the Coulomb blockade region is calculated by applying a square-wave voltage pulse to the gate electrode. For specific conditions for the left and the right tunneling barriers, the tunneling current is theoretically calculated, and the tunneling rate and the relaxation time are extracted. The feasibility of this technique is demonstrated by using simple simulations based on rate equations that describe the time-dependent transport. 본 연구에서는 양자점에 존재하는 전자의 에너지 준위간 전이 시간 (첫 번째 여기 준위로부터 바닥 준위로의 전이 시간)의 범위를 쿨롱봉쇄 영역에 있을 때 게이트 전극에 계단파를 인가하여 계산해 낸다. 어떤 특별한 바이어스 조건을 왼쪽과 오른쪽 터널 장벽에 인가한 상태에서 터널링 전류를 이론적으로 계산하고 터널 장벽을 통과하는 전자의 터널링 율과 양자점 내의 에너지 준위 간의 전이율을 이 계산 결과로부터 도출해 낸다. 시간 의존 수송 현상을 기술하는 rate 방정식을 사용하여 전이율을 이론적으로 계산 해 봄으로써 이 방법의 적용 가능성을 판단한다.

석탑 탑구(塔區)의 역할 및 변천에 관한 연구

정해두,장석하,Chung, Hae-Doo,Jang, Suk-Ha 한국건축역사학회 2010 건축역사연구 Vol.19 No.1

Korea's stone buildings are varied in their types such as stone pagodas, stone lanterns, stone bridges, stoneworks, etc. These account for more than 30% over the entire cultural properties, but research achievements are lacking compared to wooden buildings. Accordingly, this study aims to identify the shape, role and transition of Tapgu, which had been used to set up boundary at a stone pagoda, one of the stone buildings. The 20th stone pagodas, which have relative accuracy in its forming year, have been studied around national treasure or treasure between 7th century and 9th century. There are a lot of different opinions about the role and meaning of Tapgu, and at this writer's option, Tapgu is defined as follows: First, each structure plays a different role. A structure to pass the load in the upper part to the ground can be seen as a stair or a pedestal, but a structure to form double foundations can be considered as Tapgu. Second, Tapgu can be used to divide areas with stones or stepping stones. As a result, the shape, role and transition of Tapgu is as follows: Firstly, when it comes to its shape, Tapgu includes flagstone type, belt type, double foundation type, compound type. Flagstone type had been used to set up boundary at stone pagodas by using foundation stone, belt type by keeping apart from stone pagodas, and double foundation stone by installing dual foundation stones. Secondly, Tapgu is considered to set up boundary in the case of flagstone and plate stone, and acts like a structure which can prevent surrounding area of stone pagoda from coming up while being stuck around stone pagodas. Belt type was installed only for the purpose of forming boundary. At the bottom, double foundation stone had been used to pass the load in the upper part to the ground in the same way as the foundation stone in the upper part, and the boundaries were set varying the size. Thirdly, when it comes to the transition of Tapgu, flagstone type of boundary stone had been installed in the 7th century, and belt type of boundary stone had been mainly installed in the 8th century. And double foundation stone had been installed in the 9th century. Comprehensively, flagstone type and belt type had been made around the 7th and 8th century when Tapgu was regarded important and stone pagoda started to be built. At the turn to the 9th century, the role of Tapgu had been increasingly losing in the construction of stone pagoda, and foundation stone started to appear.

석탑 기단부 적심구성방법에 대한 특성 고찰 - $7{\sim}8$세기 석탑 중 해체 수리한 석탑을 중심으로 -

정해두,장석하,Chung, Hae-Doo,Jang, Suk-Ha 한국건축역사학회 2007 건축역사연구 Vol.16 No.5

Through analysing on construction cases of stupa built in A.D. 7,8th, I have researched about these : constructive methods of inner soil of stupa, spatial compositions, characteristics of structures, arrangements of inner soil and etc. And cases analysed are six ; Mireuksajiseoktap(stone pagoda of Mireuksa Temple site), Gameunsajisamcheumgseoktap(three storied stone pagoda of Gameunsa Temple site), Goseonsajisamcheungseoktap(three storied stone pagoda of Goseonsa Temple site), Wolseong nawolliocheungseoktap(five storied stone pagoda in Nawonri, Wolseong), Guksagokseoktap(three storied stone pagoda in Guksa valley), Giamgokseoktap(three storied stone pagoda in Giam valley). Additionally we researched about inner soil of Sacheonwangsaji tapji(basement of stone stupa site in Sacheonwang Temple site) to speculate on composition of Synthetically, the foundation could be divided as core space and outer space. ; the former as structural function and the latter as ornamental function. And the core area could be divided again as center column space and buffer space. The relationship between core spaces and its formation are as belows; First, according to the area of foundation and scale of stone pagoda, formations of core are differed. As the scale of stone pagoda goes bigger, and the area of foundation goes larger, the structure of stone pagoda comprised by center column type and layered-core which endure upper load independently. On the contrary, as the scale of stone pagoda goes smaller, and the area of foundation goes lesser, the structure of stone pagoda tend to use only center column to endure upper part. Second, spatial composition of core area is comprised as two spaces, one which endure upper load and buffer space which absorb side pressure and upper pressure. The buffer space tend to be used in case of those structures which could not endure side pressure or have lots of joint. In some cases, it was located below the cover stone of foundation and gained upper load. And in case that have not gained pressure from side stone, the buffer space are comprised by smalle stone or roof tile to get structural supplement.

통일신라시대 탑구(塔區)의 역할 및 변천에 관한 연구

정해두,장석하 대한건축학회지회연합회 2007 대한건축학회지회연합회 학술발표대회논문집 Vol.2007 No.1

Various stonework that stone pagoda, stone lantern, stone bridge, stone embankment exists in Korea. Nevertheless, there is little study of the stonework for wooden building.. The subject of study is stone pagoda in a.d. 7~9 century. This study aims at shape, form, role, change in Tapgu that the verge element of the stone pagoda. We hope this study become preliminary data in a study of stonework and we looking forward to reading the variety study of stonework.

두 양자점 계에서 전하 큐비트의 결 맞는 상태 분석

정해두 한밭대학교 에너지청정기술연구소 2004 에너지청정기술논문집 Vol.4 No.1

본 연구에서는 화합물 반도체 두 양자점 계에서 전하 큐비트의 결 맞는 상태 진동의 시간에 따른 변화를 조사, 분석한다. 전하 큐비트는 에너지 준위와 계의 결 맞지 않는 상태를 매우 빠른 전압펄스를 이용하여 조절 가능하게 된다. 이 전하 큐비트는 전압펄스로 인해 유기된 전류를 측정하여 분석한다. 전하 큐비트의 결 맞는 진동은 각 양자점의 기저 상태와 여기 상태의 조합이 이루어짐으로써 관측되어진다. We investigate coherent time-evolution of charge states(pseudo-spin qubit) in a semiconductor double quantum dot. The charge qubit is manipulated with a high-speed voltage pulse that controls the eigenstates and decoherence of the system, and is measured as pulse-induced current. The coherent oscillations of the charge qubit have been observed for some combinations of ground and excited states of each quantum dot.

타원편광 분석기에서 정렬오차와 사분파장판의 지연오차로 인한 뮬러 매트릭스 오차 분석

정해두,김덕현,Cheong, Hai Du,Kim, Dukhyeon 한국광학회 2014 한국광학회지 Vol.25 No.5

두 개의 회전하는 사분파장판을 가진 타원편광분석기에서 광학계가 오차를 포함하지 않는 경우와 5가지의 체계적 오차(두 개의 사분파장판의 정렬오차와 지연오차, 검광판의 정렬오차)를 포함하는 경우에 측정신호를 핏팅하여 구한 퓨리어 계수와 뮬러매트릭스와의 관계를 분석하였다. 5가지 체계적 오차를 포함하는 경우 전산모사를 이용해 비교 분석한 결과 사분파장판의 지연 오차가 정렬오차보다 뮬러매트릭스 대각선 요소에 야기하는 오차가 더 크다는 것을 찾아내었다. 각속도의 회전비를 1:5로 선택시 첫 번째 사분파장판의 초기 정렬오차와 두 번째 사분 파장판의 초기 정렬오차가 뮬러 매트릭스에 야기하는 오차가 같다는 것을 전모사를 통해 찾아 내었다. 5가지 체계적인 오차를 전산모사를 통해 분석한 결과 검광판의 정렬오차(${\epsilon}_5$)가 야기하는 뮬러 매트릭스 오차와 사분파장판의 정렬오차(${\epsilon}_3$, ${\epsilon}_4$)가 야기하는 뮬러 매트릭스 오차를 비교하면 대각선 요소($m_{22}$와 $m_{33}$)의 상대 오차는 0.18%이며 비 대각선요소($m_{23}$와 $m_{32}$)는 2배 차이가 남을 찾아내었다. 이 결과들을 활용하여 측정대상 물질의 보다 정확한 뮬러매트릭스를 얻을 수 있다. Using an ellipsometer with dual rotating quarter-wave plates, we have analyzed the relationship between Fourier coefficients and Mueller matrices in the cases of an error-free optical system and of five systematic errors (alignment errors and retardation errors in the quarter-wave plates, and alignment error in the analyzer). In the case with five systematic errors, simulation results show that retardation errors cause more error in the diagonal elements of the Mueller matrix than do alignment errors. We have found that errors in the Mueller matrix caused by initial misalignment of the dual quarter-wave plates were the same. We have chosen the rotation rates of two quarter-wave plates such that the rotational frequencies ${\omega}_1$ and ${\omega}_2$ differ by a factor of 5, i.e. ${\omega}_2=5{\omega}_1$. The simulation results show 0.18% relative error in the diagonal elements ($m_{22}$ and $m_{33}$) and 200% relative error in the off-diagonal elements ($m_{23}$ and $m_{32}$), when we compare errors caused by misalignment of the analyzer to those caused by initial misalignment of the quarter-wave plates. We can use these results in measuring accurate Mueller matrices of optical materials.

기능성 나노소자 분석 : 양자점, 큐비트

정해두 한밭대학교 2005 한밭대학교 논문집 Vol.22 No.-

양자점과 양자 비트와 같은 가능성 나노소자에 대한 최근의 연구를 다룬다. 반도제 두 양자점에서 전하 상태의 결맞는 진동의 시간에 따른 변화를 분석한다. 전하 큐비트는 계의 고유상태와 결맞지 않는 상태를 조절하는 매우 빠른 전압펄스에 의해 조절되어진다. 전하 큐비트의 걸맞는 상태 진동이 측정되어지고 분석되어졌다. 양자점 측정을 위해 새로운 형태의 간단한 투과형 초고주파 단일 전자 트랜지스터가 고안되어졌다. 이 고안된 새로운 시스탬이 초고주파 단일 전자 트랜지스터를 위해 기가헤르츠 (GHz) 영역에서 실험되어졌다. 단일 전자 터널링 전류에서 l/f 잡음을 측정함으로써 GaAs 양자점 소자에서 배경전하 요동(background charge f1uctuation)을 조사 분석했다. 이 전류 잡음은 구속 전위 요동과 터널 장벽의 요동으로 이해될 수 있다 분석한 전위 요동은 온도가 증가함에 따라 거의 선형적으로 증가한다.

Electron Spin Resonance Line-widths of Carbon Nanotubes based on the Hyperfine Interaction

박정일,정해두 한국자기공명학회 2015 Journal of the Korean Magnetic Resonance Society Vol.19 No.1

The Kubo formalism and utilizing the projection operator technique (POT) introduced by Kawabata, the electron spin resonance (ESR) line-shape formula for carbon nanotubes through the hyperfine interaction introduced earlier in terms of POT. We can see that the line-width decreases exponentially as the temperature increases. The spin relaxation time show gradual decrease as magnetic field becomes larger. The analysis reveals the peculiarities in spin relaxation inherent to one dimensional system at low temperature and weak magnetic fields. Thus, the present technique is considered to be more convenient to explain the carbon nanotubes as in the case of other optical transitions.

ZnTe 단결정 박막의 결정구조와 광학적 특성 연구

김대중,정해두,김덕현,김호경,김봉진,이종원,최용대 한국물리학회 2012 새물리 Vol.62 No.6

ZnTe epilayers were grown on GaAs (100) substrates by using the hot-wall epitaxy method. X-ray diffraction (XRD) was used to study the crystallinity and the crystal orientation of the epilayer. The surface morphology of the epilayer was observed by using a field-emission scanning electron microscope (FESEM). In order to investigate the binding states and their chemical compositions, we characterized the ZnTe epilayers by using X-ray photoelectron spectroscopy (XPS). Their optical properties were investigated in the photon energy range between 1.5 and 8.7 eV at room temperature by using spectroscopic ellipsometry (SE). The obtained data were analyzed for the critical points, such as the E_0, E_0+△_0, E_1, E_1+△_1, Estructures, of the pseudodielectric function spectra <ε(E)> = <ε_1 (E)> +i<ε_2(E)>. Also, the pseudodielectric-function-related optical constants of ZnTe, such as the refractive index n(E) and the extinction coefficient k(E), were analyzed. Numerical calculations of second derivative spectra of the pseudodielectric functions <ε(E)> of our ZnTe epilayer were carried out for a further analysis of the critical points. We observed the E_1, E_1+ △_1 peaks at energies above 6.0 eV through the SE analysis. 열벽 적층 성장법을 이용하여 고품질의 ZnTe 단결정 박막이 성장되었다. 성장된 박막들은 결정구조를 알아보기 위하여 XRD 패턴을 이용하였고,박막의 표면 상태를 알아보기 위하여 SEM을 측정하였다. 또한 박막의화학성분과 결합상태를 알아보기 위하여 x선 광전자분광분석기(x-ray photoelectron spectroscopy;XPS)를 이용하였다. 박막의 광학적 특성을알아보기 위하여 분광 엘립소미트리 (spectroscopic ellipsometry;SE)를사용하여 실온에서 1.5 - 8.7 eV 사이 포톤에너지 범위에서측정되었다. 측정된 데이터들은 유사유전함수 스펙트럼<ε(E)> = <ε_1 (E)>+ i<ε_2(E)>에나타난E_0, E_0+△_0, E_1, E_1+△_1, E와 같은임계점 구조에 대하여 연구하였다. 또한 박막의 복소 유전함수와 밀접한관계를 가지고 있는 굴절지수 n(E), 소광계수 k(E)와 같은 광학적특성에 관하여 연구하였다. SE를 이용하여 획득된 데이터의 이계도함수를이용하여 각각의 임계점 피크들을 구하였고, 6.0 eV 이상에서 나타난E_1, E_1+ △_1 임계점 피크들이 연구되었다.

Electron Spin Resonance Investigation of Fe3+ in Crystalline LiNBO3 Under the Polarized External Radiation

박정일,정해두 한국자기공명학회 2013 Journal of the Korean Magnetic Resonance Society Vol.17 No.2

We study the electron spin resonance line-width (ESRLW) of in crystalline ; the ESRLW is obtained using the projection operator method (POM) developed by Argyres and Sigel. The ESRLW is calculated to be axially symmetric about the and is analyzed by the spin Hamiltonian with an isotopic factor at a frequency of . The ESRLW increases exponentially as the temperature increases, and the ESRLW is almost constant in the high-temperature region (). This kind of temperature dependence of the ESRLW indicates a motional narrowing of the spectrum when ions substitute the ions in an off-center position. It is clear from this feature that there are two different regions in the graph of the temperature dependence of the ESRLW.