衝擊荷重을 받는 複合材料 圓筒쉘의 動的擧動 硏究

이기두 忠南大學校 1993 국내석사

통계 데이터베이스의 보안증진

이기두 崇田大學校 産業大學院 1985 국내석사

마이크로스트립 라인 구조를 이용한 고온초전도 공진기와 협대역 필터의 제작 및 특성 연구

이기두 漢陽大學校 大學院 2000 국내석사

마이크로파(microwave) 영역(특히 현재 PCS 기지국용으로 쓰이는 1.8~1.9GHz)에서 동작하는 고온초전도 공진기(resonator)와 필터(filter)를 상용화된 컴퓨터 설계 프로그램을 이용하여, 높은 품질계수(Quality factor)와, 우수한 스커트(skirt) 특성을 갖도록 디자인하고, 동작특성을 조사하였다. 디자인된 공진기와 필터의 특성은 network analyzer와 저온측정장치(cryosystem)를 이용하여 저온에서 측정하여, 컴퓨터 프로그램을 통한 결과와 비교하였다. 또한 소자 적용을 위해, 고온초전도 박막을 제작하기 위한 Pulsed Laser Deposition의 최적조건을 찾기 위한 일련의 실험을 진행하였다. 고온초전도 공진기와 필터를 제작하기 위해 필요한 특성치의 계산은 정수소자(lumped element)로 환산하여 계산하였으며, 등가회로를 구성하였다. 그리고, 각각의 정수소자에 해당하는 분포소자(distributed element)를 interdigital 형태와 meander-line 형태로 디자인하고, 상용화된 circuit simulator인 Ansoft사의 Serenade 8.0을 이용하여 설계하고, 등가회로의 공진특성과 비교하였다. 공진기 및 필터의 최적화는 프로그램에서 제공한 최적화 도구를 이용하였다. 또한 이렇게 구해진 디자인은 상용화된 EM simulator인 Zeland사의 IE3D 7.02로 동작특성을 조사하여, 각각의 결과를 비교하였다. 이때 구해진 공진기는 삽입손실(insertion loss)이 -0.1dB이하이고, 100,000 이상의 무부하(unloaded) Q 값을 갖고, 또한 필터는 상대적으로 작은 크기로 디자인되어, 1.845GHz에서 1%내외의 대역비와 -0.5dB이하의 낮은 삽입손실과 -50dB/3MHz의 우수한 스커트특성을 갖는다. 스커트 특성의 향상을 위해 필터에 투과영점(transmission zero) 특성을 갖도록, 전송선로 결합과 비트 형태의 변형을 시도하였다. 고온초전도 박막을 사용한 소자는 일반적인 UV를 이용한 광식각(photolithography) 방법과 ion milling 방법으로 제작되었으며, packaging되어 저온측정장치에서 network analyzer를 이용하여 측정되어졌고, 컴퓨터 계산 결과와 비교하였다. 고온초전도 박막의 제작은 harmonic 된 Nd:YAG pulse laser를 이용한 PLD(Pulsed Laser Deposition) 방법으로 시도되었다. 산소 분압의 변화에 따른 c-축 격자상수(lattice constant)를 비교하여 산소의 적절한 함량을 제공할 수 있는 분압을 300mTorr로 결정하였다. 박막의 c-축 epitaxial 성장 및 격자상수를 확인하기 위해 XRD(X-Ray Diffraction)측정을 하였고, SEM(canning electron Microscopy)을 이용하여 그 표면상태를 확인하였다. 또한 lock-in amplifier를 이용한 사단자측정법(four probe measurement method)으로 박막의 전이온도(transition temperature)를 측정하였다.

放射基底函數補間을 適用한 流體-構造 連繫 空彈性 解析技法에 關한 硏究

이기두 忠南大學校 大學院 2011 국내박사

The flutter is one of the most dangerous phenomena that can occur during flight. It is excited by abnormal aerodynamic forces coupled with aircraft structures and external stores configuration. Especially in the transient speed region, the occurrences of flutter and buffet increase because of the unstable aerodynamics caused by shock wave. For such reason, analysis of the flutter in transient region has been a big issue in designing and testing the aircraft. The CFD-CSD couple aeroelastic simulations are recognized as the most accurate schemes because they offer significant advantages in terms of accuracy of nonlinear flow and structure calculation, especially in the transonic regime. However, in spite of their accuracy, application of this approach for an actual aircraft model is very time consuming. In this research, effective interpolation and mapping methods were investigated by using radial basis function. To develop the aeroelasticity analysis method it used the developed interpolation method with commercial fluid and structure analysis software. Finally, by applying to this newly developed fluid-structure interaction technique, research on aeroelasticity characteristics of gliding object and horizontal tail of F-5 aircraft installed on the gliding object were carried out. This study can be summarized and concluded as follows; 1. In this research, effective applications of interpolation and mapping methods by using radial basis function were investigated. These are the essential factor to execute analysis of fluid-structure interactions. As a result, compactly supported radial basis function was able to solve bigger problems compared to a globally supported radial basis function. The calculative limitations, however, were still existed. To solve this problem, a partition of node method was suggested. Not only the simple model, but also the whole body model of aircraft could be analyzed using this method. 2. Dynamic model updating technique which is required when the fluid-structure interaction analysis proceeds was defined. Then, the utilization of the commercial software with updating technique was described. Multi-purpose optimization technique was used to reduce discrepancies in analysis and test results of the wing static deflection, natural frequencies and modal assurance criterion(MAC). MAC estimates the mode shape consistency. Finite element software ABAQUS program was used and interacted with MATLAB software optimization module to develop the optimum solution. 3. Code-Bridge program which couple between fluid and structure analysis by using CFD and CSD commercial software with the developed interpolation and mapping method was developed. MATLAB program was used to develop this program. CFD analysis can implement the Euler and Navier-Stokes Equation which is supplied by FLUENT. CSD analysis can easily express lots of nonlinear states by using direct integral method. 4. In this research, by using the developed Code-Bridge, aeroelasticity characteristics of gliding object of the wing and the horizontal tail of aircraft when the gliding object is installed on aircraft's wing were studied. As a result, even though the aeroelasticity of the gliding object wing slightly changes according to the angle of the attack, the flutter doesn't occur at the considered mach number in this study. Also, no flutter occurred on the aircraft's horizontal tail when the gliding object is installed on aircraft's wing as well as the pylon, fuel tank, and the CBU-58 at considered mach number. Developed Code-Bridge can be used to solve similar problems for other types of aircrafts(F-16, F-4, F-15, F-50) and to estimate the integrity of gliding object with variety of boundary conditions(Mach number, angle of attack, height, etc.). It can also be used in cases when it's difficult to proceed flight tests such as emergency fuel tank separation trajectory analysis with fuel sloshing and structural deformation.

중소제조업 녹색 경영 체제 구축 방안

이기두 한양대학교 산업경영디자인대학원 2009 국내석사

지금까지 기업의 환경 경영 활동은 소극적인 정부 기관의 환경 규제를 회피 하려는데 중점 되어져 왔으며, 이로 인해 환경 관리는 기업 활동에 대한 어쩔 수 없는 비용 지출로 여겨져 각 기업들에서 소극적으로 대처해 온 것이 사실이다. 그러나 최근 들어 국내외적으로 환경오염으로 인한 지구 온난화, 각종 국제 환경 무역 규제 등 환경 문제의 심각성이 강조 되고 있어, 지구촌 대중들은 환경 보존의 중요성을 다시한번 심각하게 깨닫고 있는 현실이며 따라서 기업의 환경 경영 요구도 그 어느때보다 높아지고 있다. 이런 상황에서 특히 국내 많은 제조업 중소기업들은 대기업들과의 부품/제품 납품등의 연관성을 맺고 있어 환경 경영의 실패는 자못 완제품의 환경 규제 미 준수에 연관될 경우 대기업의 피해가 연쇄적으로 중소기업에까지 미쳐 자금력이 튼튼하지 않은 중소 업체들은 도산의 위기까지도 불러올 수 있는 상황이나, 중소 규모 기업체들은 환경 경영에 있어서 자금난과 인력부족 등으로 인하여 가중되는 어려움을 호소하고 있는 것 또한 현실이다. 중소기업은 규모의 크기나 기업 문화, 최고 경영자의 인식에 따라 차이가 있을 수 있으므로 기업의 실정에 맞게 환경 경영 체계를 확립하는 것이 중요하다. 최고 경영자의 의지 및 지원이 절실히 요구 되므로 문서화된 환경경영 방침을 수립한 후 대내외에 공표하고, 기업의 여건에 따라 전담 조직을 두거나, 전담 조직을 둘 수 없는 형편일 경우 정부 지원 및 지역 협력 체제를 통하여 전문 지식을 습득하고, 전사원들의 환경 경영 요원화를 추진하기 위하여 기능별 명확한 역할과 책임을 확보한 후 ISO14001 인증 체계를 추진하여 환경 경영 체계의 기본틀 확립 및 대내외에 홍보 효과를 얻어내고, 전과정 평가(LCA)를 통한 친환경 제품 생산 및 무역 규제 충족, 원가 절감 노력을 해나가는 것이 필요하다. 회사의 모든 활동을 환경과 연계하여 검토하고 실행해 나가도록 하고, 환경 경영 활동을 기업의 이미지 제고 및 대내외 경쟁력 강화, 손실 최소화에 따른 이윤 극대화로 연결 시켜야 하겠다. So far, Environmental management system of companies have been passive policy and focused to avoid government reinforcement, therefore the cost of Environmental administration treated as unwanted expenses by companies. However, recent Global warming issue come from environmental pollution and international environmental trade regulations make Environmental issue more serious. People in globe getting realized the importance of environmental management more and more. In this situation, especially small or midium size manufacturing companies have close business relationship with large-sized companies to supply products. If the small or midium size companies fails to comply Environmental Business Administration and it affects to the Environmental regulation for products, it may cause serious financial crisis due to huge claim from customers, however small or midium size companies confess difficulties of financially and human resources to establish Environmental business administration system. As the result of this study, because Small or Midium sized manufacturing companies have various size, culture, management willingness, it is important to establish the Green business administration system based on the companies' situation. As the system needs top management's strong commitment, the first written Environmental policy which contains top managements' clear intention for green business administration , publish internally and externally The second, if a company has enough capability then has full time environmental staff, otherwise company needs to utilize governement support and regional committee to earn technical knowledge, designate clear role & responsibility of each departments or functions to establish all employees' involvement. The third, through setting up ISO14001 program, establish basic system of Environmental management system also inform to public to upgrade company image. Through Life Cycle Assessment, produce eco-friendly products, comply internal environmental trade restrictions, save cost. Additionally all activities within company relates to green business administration system, utilize green business administration activities to upgrade company image, competitiveness and minimization of loss, those will bring maximize the company profit.

전착공정을 이용한 Cu2ZnSnS4 박막태양전지

이기두 高麗大學校ㆍ韓國科學技術硏究院 Green School 大學院 2013 국내석사

Abstract The kesterite Cu2ZnSnS4 (CZTS) has attracted a lot of interest as a next generation absorber material of thin film solar cells. Because the material features an optimal band gap of 1.45 ~ 1.6 eV, a high optical absorption coefficient of 105 cm–1, and the intrinsic p-type semi-conductivity resulting from the substitution of Zn atoms with Cu atoms 1-4. Another advantages of using CZTS is that its elements are earth abundant (cf. In in Cu(In,Ga)Se2), non-toxic (cf. Cd in CdTe), and cheap. In order to further reduce the production cost, a lot of efforts have been made to use non-vacuum processes for preparing CZTS thin films. A lot of synthetic approaches have been circumvented in attempts to prepare CZTS thin films, including the spray pyrolysis 5, sputtering 6-9, sol-gel 10, pulsed-laser-deposition 11, and the nanoparticle methods 12. In terms of the production cost, non-vacuum processes possess advantages over the vacuum counterparts 13. Among various non-vacuum processes, a hydrazine-based solution process has reported the highest conversion efficiency of 11.1%, but extremely toxic and explosive hydrazine solvent has been a critical issue for commercialization of the technology 55. The electrochemical deposition can be a good alternative synthetic process15-22, as it can be done in a large scale and roll-to-roll process. Recently, a decent efficiency of 7.3% has been reported using the electrochemical deposition of metallic precursor films and the subsequent sulfurization process 23. In this study, we fabricated metallic Cu-Zn-Sn (CZT) precursor thin films via electrochemical deposition from aqueous metal salt solution on Mo-coated soda-lime glass substrates, and the influence of the subsequent sulfurization condition on the morphology, composition and structure of the final CZTS thin films was investigated. Both rapid thermal annealing (RTA) equipment and normal annealing equipment were used for a systematic control of the sulfurization process parameters. The composition and thickness of the precursor films were controlled by adjusting the concentration of the deposition solution, deposition potential and time. The composition of the as-deposited CZT layers were controlled to have a desired Cu-poor and Zn-rich composition (Cu / (Zn + Sn) : 0.7 ~ 0.9, Zn / Sn : 1.0 ~ 1.3), but the composition, crystalline structure, grain growth, and electrical properties of final CZTS thin films were significantly affected by the annealing conditions. And the metallic precursor films were prepared using the one-pot electrochemical deposition process, the effect of the sulfurization parameter, in particular the heating rate, has been investigated. The solar cell properties of thin film solar cells using the CZTS active layer, such as photocurrent density-voltage (J-V) characteristics, external quantum efficiency (EQE) were also investigated.

A Study on Circuit Technology for ESD (Electro-Static Discharge) Protection

이기두 성균관대학교 일반대학원 2017 국내박사

This thesis discusses an analysis and improvement method for an ESD protection circuit designed to improve the Electro-Static Discharge (ESD) tolerance of Integrated Circuits (ICs) fabricated using advanced CMOS technology. ESD failure is one of the most important issues regarding the reliability of semiconductor ICs. Various studies have attempted to produce devices that are more robust against ESD, but new ESD issues have arisen due to the continued down-scaling of devices, application of advanced semiconductor technology, and introduction of new device concept and material. Therefore, it is more important than ever to develop new methods to verify ESD protection circuits and to attempt their continuous improvement, which is an important motive connected to the subject of this thesis. The first topic is the study of stacked drivers used to increase the ESD immunity of the output driver of recent I/O systems. First, a test circuit and the test method to verify the ESD protection circuit are introduced, and then the results are added of the systematic analysis of the behavior of the ESD protection circuit during an ESD event. The test circuit designed for verification includes pre-drivers and rail-based power clamps to faithfully represent the output driver circuits in an actual I/O system in ICs, and the impacts of all possible pre-driver connections and stacked driver sizing are examined with the Very Fast Transmission Line Pulse (VF-TLP). When the input of the pre-driver connected the top MOSFET is grounded, the failure current (IT2) is verified to improve by ~110% relative to the worst case where both pre-driver inputs are tied to VDD. Also, a simple trigger circuit that guarantees the electrical connection is proposed to provide better ESD immunity. In addition, a simulation method using SPICE is introduced to verify the total progress of applying the ESD pulse generated by the VF-TLP to the device. The second topic is the study of a new concept to prevent ESD failure by storing the ESD information. The proposed ESD circuit detects an occurrence of ESD at the system level and stores the detected ESD occurrence level. ReRAM (Resistive Random-Access Memory) is used to store the ESD level regardless of whether the system is operating or not. ReRAM is non-volatile memory (NVM) that is not erased even when there is no power and has the characteristic that the resistance changes depending on the applied voltage, so it plays the role of storing the ESD information generated without power. Through ReRAM modeling and SPICE simulation, it is verified that the ESD voltage causes a change in the resistance state of the ReRAM (161KΩ → 250Ω) and ESD level is stored as the corresponding ReRAM resistance value. Also, it is confirmed that the resistance value of ReRAM can be converted to 4-bit digital code through current mode ADC.