To reduce manufacturing costs of crystalline silicon solar cells, silicon wafers have become thinner. In relation to this, the properties of the aluminium-back surface field (Al-BSF) are considered an important factor in solar cell performance. Generally, screen-printing and a rapid thermal process (RTP) are utilized together to form the Al-BSF. This study evaluates Al-BSF formation on a (111) textured back surface compared with a (100) flat back surface with variation of ramp up rates from 18 to 89˚C/s for the RTP annealing conditions. To make different back surface morphologies, one side texturing using a silicon nitride film and double side texturing were carried out. After aluminium screen-printing, Al-BSF formed according to the RTP annealing conditions. A metal etching process in hydrochloric acid solution was carried out to assess the quality of Al-BSF. Saturation currents were calculated by using quasi-steady-state photoconductance. The surface morphologies observed by scanning electron microscopy and a non-contacting optical profiler. Also, sheet resistances and bulk carrier concentration were measured by a 4-point probe and hall measurement system. From the results, a faster ramp up during Al-BSF formation yielded better quality than a slower ramp up process due to temperature uniformity of silicon and the aluminium surface. Also, in the Al-BSF formation process, the (111) textured back surface is significantly affected by the ramp up rates compared with the (100) flat back surface.

The binomial option pricing model is widely used to understand pricing an option which is a financial derivative. The Model presents very important characteristics in deciding a price of an option. First, a value of option is decided independently with probabilities that stock prices are ascending or fall. Second, an option pricing is not depend on investors' risk preferences. When an option is evaluated, this paper may clear that investors had to consider the probabilities of a stock price's movements and their own preferences for a risk.

The impact simulation of composite safety barriers was carried out for three kinds of stacking section. Stacking section C with the smallest deformation was selected as the optimal section.

대체연료 충전을 위한 기반시설의 효율적 설계 및 개발은 신에너지 경제의 촉진을 위해 필요하다. 본 논문은 GIS와 입지모델을 결합하여 공간의사결정지원 시스템(SDSS)의 원형을 개발하였다. 사용된 입지 모델은 일회 주유에 따른 주행거리가 제한적인 대체연료 차량을 대상으로 최대의 충전 서비스를 제공할 수 있는 지점에 충전소를 입지하며, 이때 운전자는 주유를 위해 기-종점 간의 최적경로에서 벗어나 우회할 수도 있다고 가정한다. 개발된 SDSS는 확장가능할 뿐 아니라 의사결정자가 다양한 수요 시나리오를 탐색할 수 있다. 이를 통해 대체연료차 운전자의 우회 행태, 시장 수요의 공간적 분포, 주행거리, 기존 시설물에 관한 상이한 가설을 세우고 그 결과를 실험할 수 있다. 주어진 조건을 만족하는 최선의 충전소 위치에 관한 결과는 지도 및 통계와 같은 다양한 산출물로 보고된다.

The aim of this study was to investigate microstructures and mechanical properties of nano-sized Ti-35 wt.%Nb-7 wt.%Zr-10 wt.%CPP composite fabricated by high energy mechanical milling (HEMM) and pulse current activated sintering (PCAS). Grain growth of the mechanically milled powder was prevented by performing PCAS. The principal advantages of calcium phosphate materials include: similarity in composition to the bone mineral, bioactivity, osteoconductivity and ability to form a uniquely strong interface with bone. The hardness and wear resistance property of nano-sized Ti-35 wt.%Nb-7 wt.%Zr-10 wt.%CPP composites increased with increasing milling time because of decreased grain-size of sintered composites.

We investigate grain growth behavior of poly-crystalline Mg sheet having strong basal fiber texture using phase field model for grain growth and micro-elasticity. Strong initial basal texture was maintained when external load was not imposed, but was weaken when external biaxial strain was imposed. Elastic interaction between elastic anisotropy of Mg grain and external load is the reason why texture evolution occurs.

Electro-Discharge Sintering (EDS) employs a high-voltage/high-current-density pulse of electrical energy, discharged from a capacitor bank, to instantaneously consolidate powders. In the present study, a single pulse of 0.57-1.1 kJ/0.45 g-atomized spherical powders in size range of 10~30 and consisting of -(Ti, Zr) and icosahedral phases were applied to examine the structural evolution of icosahedral phase during EDS. Structural investigation reveals that high electrical input energy facilitates complete decomposition of icosahedral phase into C14 laves and -(Ti, Zr) phases. Moreover, critical input energy inducing decomposition of the icosahedral phase during EDS depends on the size of the powder. Porous Ti and W compacts have been fabricated by EDS using rectangular and spherical powders upon various input energy at a constant capacitance of in order to verify influence of powder shape on microstructure of porous compacts. Besides, generated heat () during EDS, which is measured by an oscilloscope, is closely correlated with powder size.

Precipitation of the ordered icosahedral quasicrystal in Mg-6wt%Zn-1wt%Y alloy has been characterized bytransmission electron microscopy observations. The lamellar-type icosahedral qusicrystal phases (I-phase) with the face-centeredicosahedral (FCI) structure are observed in alloy after solution treatment at 550oC. In the alloy annealed at 400oC, polygon-shaped I-phases are observed in the α-Mg matrix. The interfaces of the I-phase with the matrix are facetted and the facets areon five-fold and two- fold plane of the I-phase. The orientation relationship of the I-phase with the matrix is determined tobe [I5]I//[001]Mg, (2f)I//()Mg and [I2]I//[311]Mg, (5f)I//()Mg. The icosahedral grains are occasionally found to be twinnedwith one of the five-fold axis as the twin axis. The twin boundaries appear to be fairly straight and perpendicular to the five-fold twin axis. The icosahedral twin can be expressed as a rotation of 63.4o or 116.6o around two fold zone axis.

어린이나 청소년을 대상으로 한 에듀게임은 타 게임과는 다르게 구매자와 이용자가 뚜렷하게 구분된다는 특징을 가지고 있다. 하지만 에듀게임의 구매자 측면에서의 국내 연구는 부족한 실정이다. 따라서 본 연구는 구매자 측면에서 에듀게임을 구매할 때 의사를 결정하는 요인을 찾아내고, 구매 결정 요인을 중심으로 타 게임과의 특징적 차이점을 비교하고 파악함으로써 향후 에듀게임에 관한 연구 및 에듀게임 제작에 참고가 되고자 한다.

본 논문은 사회심리학 이론 중 사회정체성 이론에 근거하여 현지국의 경제발전과 집단주의 수준이 한국 다국적기업 해외자회사의 소유지분 결정에 미치는 영향을 살펴보고자 한다. 본 연구는 현지국에 비해 상대적으로 경제적으로 덜 발전된 국가에서 유래한 다국적기업들은 출신 국가로 인한 비용을 줄이기 위해 보다 높은 수준의 지분을 선택한다고 주장한다. 뿐만 아니라 현지국의 집단주의 수준이 현지국의 경제발전 정도와 해외자회사의 지분율 간의 관계를 정(+)의 방향으로 조절한다고 주장한다. 32개국에 위치한 235개의 해외자회사를 대상으로 서열 로지스틱 회귀분석과 토빗 분석을 통해 이상의 주장을 실증적으로 검증한다.

Under limited resources such as budgets and experts, it is essential to set promotion priorities for standardization work items on IPv6 (Internet Protocol version 6) multi-networking technologies. Opinions of domain experts are surveyed and analyzed utili

The microstructure and Cu diffusion barrier property of Ta-Si-N films for various Si and N compositions were studied. Ta-Si-N films of a wide range of compositions (Si: 0~30 at.%, N: 0~55 at.%) were deposited by DC magnetron reactive sputtering of Ta and Si targets. Deposition rates of Ta and Si films as a function of DC target current density for various N2/(Ar+N2) flow rate ratios were investigated. The composition of Ta-Si-N films was examined by wavelength dispersive spectroscopy (WDS). The variation of the microstructure of Ta-Si-N films with Si and N composition was examined by X-ray diffraction (XRD). The degree of crystallinity of Ta-Si-N films decreased with increasing Si and N composition. The Cu diffusion barrier property of Ta-Si-N films with more than sixty compositions was investigated. The Cu(100 nm)/Ta-Si-N(30 nm)/Si structure was used to investigate the Cu diffusion barrier property of Ta-Si-N films. The microstructure of all Cu/Ta-Si-N/Si structures after heat treatment for 1 hour at various temperatures was examined by XRD. A contour map that shows the diffusion barrier failure temperature for Cu as a function of Si and N composition was completed. At Si compositions ranging from 0 to 15 at.%, the Cu diffusion barrier property was best when the composition ratio of Ta + Si and N was almost identical.

Specific heat of a crystal is the sum of electronic specific heat, which is the specific heat of conduction electrons, and lattice specific heat, which is the specific heat of the lattice. Since properties such as crystal structure and Debye temperature do not change even in the superconducting state, the lattice specific heat may remain unchanged between the normal and the superconducting state. The difference of specific heat between the normal and superconducting state may be caused only by the electronic specific heat difference between the normal and superconducting states. Critical temperature, at which transition occurs, becomes lower than Tc0 under the influence of a magnetic field. It is well known that specific heat also changes abruptly at this critical temperature, but magnetic field dependence of jump of specific heat has not yet been developed theoretically. In this paper, specific heat jump of superconducting crystals at low temperature is derived as an explicit function of applied magnetic field H by using the thermodynamic relations of A. C. Rose-Innes and E. H. Rhoderick. The derived specific heat jump is compared with experimental data for superconducting crystals of MgCNi3, LiTi2O4 and Nd0.5Ca0.5MnO3. Our specific heat jump function well explains the jump up or down phenomena of superconducting crystals.

In this paper, double texturization of multi crystalline silicon solar cells was studied with laser and reactive ion etching (RIE). In the case of multi crystalline silicon wafers, chemical etching has problems in producing a uniform surface texture. Thus various etching methods such as laser and dry texturization have been studied for multi crystalline silicon wafers. In this study, laser texturization with an Nd:YVO4 green laser was performed first to get the proper hole spacing and 300μm was found to be the most proper value. Laser texturization on crystalline silicon wafers was followed by damage removal in acid solution and RIE to achieve double texturization. This study showed that double texturization on multi crystalline silicon wafers with laser firing and RIE resulted in lower reflectance, higher quantum yield and better efficiency than that process without RIE. However, RIE formed sharp structures on the silicon wafer surfaces, which resulted in 0.8% decrease of fill factor at solar cell characterization. While chemical etching makes it difficult to obtain a uniform surface texture for multi crystalline silicon solar cells, the process of double texturization with laser and RIE yields a uniform surface structure, diminished reflectance, and improved efficiency. This finding lays the foundation for the study of low-cost, high efficiency multi crystalline silicon solar cells.