http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
- 검색키워드
- 저자 : 권일영 (검색결과 3 건)
-
-
이 연구에서 우리는 injection annealing system 을 이용하여 와이드 밴드갭을 가지는 Cu(InGa)S2 의 성능을 증가시키는 효율적인 방법을 제시한다. Injection annealing system 은 원하는 온도에서 열처리를 할 수 있다. 따라서, 이차 상이 형성 될 수 있는 온도 범위를 지날 수 있어 이차 상 형성 방지에 효율적이다. Injection annealing system 을 사용하여 550℃가 넘는 온도에서 열처리함으로써 CIGS 박막의 표면에 형성된 이차 상인 InSx 를 효율적으로 제거할 수 있다. 그에 따라 이차 상 제거는 CIGS 태양전지에 좋은 P-N 접합을 형성할 수 있다. 그러므로, 이차 상의 제거에 의해서 CIGS 태양전지의 성능이 상당히 증가하게 된다. 게다가 우리는 550–640℃ 범위에서 열처리 온도가 증가할수록 CIGS 의 open-circuit-voltage (VOC)이 강화되는 것을 관찰했다. 이는 어닐링 온도 증가에 따라 CIGS 내의 결함이 감소하게 된 것으로 예상된다. Injection annealing system 을 사용함으로써 통해서 CIGS 태양전지는 12.16%의 효율을 달성했다.
-
Modeling and simulation on dynamics and instability of non-Newtonian fluids in thin film processes
권일영 Korea University 2017 국내박사
This thesis deals with instability and uniformity of two typical systems involved in the thin film process, i.e., polymer thin film manufacturing and concentrated suspension system under sheared flows. With numerical approaches, unique dynamic features of each system have been studied in two parts. In the first part, draw resonance, as the common instability in the extensional deformation processes for thin threads or films, has been studied in isothermal 1-D fiber spinning and 2-D film casting processes and its onset conditions have been determined by frequency response method (Kase and Araki, 1982). The original method has been extended to viscoelastic fluids and secondary force-included system in the fiber spinning process, and then applied to the film casting process with viscoelastic fluids. Thanks to the method used in here, stability windows (or operability windows) for stable operations of the 2-D film casting system have been constructed, which have not been presented before using linear stability analysis. The windows include the results of Newtonian and viscoelastic fluids, the upperconvected Maxwell and Phan-Thien and Tanner models, as the constitutive equation of molten polymers. The method has the merit of being able to perform sensitivity analysis of the system as well as stability analysis at a time through numerical Laplace transform converting transient responses to a step disturbance into amplifications and phase angles in frequency domain, unlike other existing methods. Also, it has been confirmed that a difference of flow velocities along streamlines, via analysis of steady-state velocity profiles in 2-D film casting, are strongly related with the tendency of onset conditions of the instability according to operation conditions. The relation between instability onsets and flow patterns allows the state of the film being drawn to be classified into planar, transition and neck-in types according to airgap distances of the process. In the second part, numerical analysis with continuum-based diffusive flux model (Phillips et al., 1992) has been conducted to observe the migration phenomenon where concentrated suspensions (in this study, Newtonian suspending fluids and unimodal spherical solid particles without buoyant force and Brownian motion) flow in parallel slit channel flows with non-symmetric velocity profile. The non-symmetric profiles in the slit channel are represented with a linear combination of drag-driven and pressure-driven flows as a planar Couette-Poiseuille flow. Factors governing the migration dynamics in the diffusive flux model (particle size, concentration, and flow length from an inlet of the channel) are unified into a non-dimensional length element,Z, and the effect of the non-symmetricity on the dynamics is presented by evolution of concentration distribution along increasing Z. From the results, symmetric flow conditions show the shortest (or smallest) Z to arrive at the fully-developed state, and increasing non-symmetricity of velocity profile (zero shear-rate position moves from the center of channel gap to a wall side) shows more longer (or larger) Z than that of the symmetric conditions. This change of Z for the development has been analytically interpreted by introducing a concept of effective diffusion gap, which is varied according to the non-symmetricity. Moreover, the non-symmetric migration from the diffusive flux model has been compared quantitatively with that from the lattice Boltzmann methods, one of the effective theoretical approaches which can solve Stokesian dynamics of suspension flows, and it has been confirmed that the continuum-based suspension system properly reflects the migration phenomenon by collisions between individual particles explained as the shear-induced migration process, even in the non-symmetric flow conditions.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
