• Current Photovoltaic Research
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• 제4권1호
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• pp.21-24
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• 2016

Chalcopyrite based (CIGS) thin films have considered to be a promising candidates for industrial applications. The growth of quality CIGS thin films without secondary phases is very important for further efficiency improvements. But, the identification of complex secondary phases present in the entire film is crucial issue due to the lack of powerful characterization tools. Even though X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and normal Raman spectroscopy provide the information about the secondary phases, they provide insufficient information because of their resolution problem and complexity in analyzation. Among the above tools, a normal Raman spectroscopy is better for analysis of secondary phases. However, Raman signal provide the information in 300 nm depth of film even the thickness of film is > $1{\mu}m$. For this reason, the information from Raman spectroscopy can't represent the properties of whole film. In this regard, the authors introduce a new way for identification of secondary phases in CIGS film using depth Raman analysis. The CIGS thin films were prepared using DC-sputtering followed by selenization process in 10 min time under $1{\times}10^{-3}torr$ pressure. As-prepared films were polished using a dimple grinder which expanded the $2{\mu}m$ thick films into about 1mm that is more than enough to resolve the depth distribution. Raman analysis indicated that the CIGS film showed different secondary phases such as, $CuIn_3Se_5$, $CuInSe_2$, InSe and CuSe, presented in different depths of the film whereas XPS gave complex information about the phases. Therefore, the present work emphasized that the Raman depth profile tool is more efficient for identification of secondary phases in CIGS thin film.

• 대한지역사회영양학회지
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• 제17권3호
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• pp.302-311
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• 2012

The purpose of this study was to provide preliminary data for better safety control over children's preference foods sold in school stores. The survey was conducted from June to July 2009, to collect 749 types of children's preference foods sold in 150 middle and high school stores nation-wide excluding Jeju Island and general and nutrition information were analyzed. Out of 749 types of snack food items, 689 and 602 snacks were sold at high school and middle school stores respectively. Among children's preference foods, cookies, bread, and ice-cream were the main items. Among them, 98% of snacks were domestic products and the price range of each individual snacks were mostly between 600 and 900 won. 27.8% of children's preference foods sold were found to be in the high calorie/low nutrition food group. Even though the proportion of candy and fruit/vegetable beverages sold were not high, their proportion in high calorie/low nutrition snack group were higher than 68.1%. Among the children's preference foods sold in middle and high school stores, carbonated drinks and ramen were continuously sold in certain middle and high schools, even though sales were prohibited. This study concludes that government, corporations and retailers should work together in developing healthier children's snack distribution environment. In addition, dairy products, which take up 15% of children's preference food, should be diversified to meet their nutrient requirements.

• 공학논문집
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• 제6권2호
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• pp.75-83
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• 2004

정보화 시대를 살아가는 우리는 인터넷을 통해 발빠른 전 세계의 정보화를 경험하고 있다. 그에 따라 생활전반에 걸친 유통, 서비스품질들이 인터넷을 통해 제공되면서 새로운 사회로 나아갈 수 있는 토대를 마련하고 있다. 따라서 컴퓨터의 사용은 현 기업에서 이루어지지 않은 업무가 없을 정도로 많이 사용되고 있다. 하지만 우리 사회에서 가장 널리 퍼져 활발한 사회활동을 하고 있는 50대 컴퓨터 사용능력은 기업에서 요구하는 수준에 미치지 못하고 있는 실정이다. 게다가 정작 그 서비스를 이용하는 주 고객층인 40대 이후의 주부 및 50대 이상들의 인터넷 사용률은 컴퓨터의 조작 미숙으로 인해 비교적 낮은 상황이다. 제시하는 시스템은 지루한 텍스트 위주의 강의가 아닌 직접 도움말에 따라 실습을 해보는시뮬레이션기법의 가상체험 강의를 인터넷을 통해 제공한다. 또한 각 수강과목은 인터넷 시작/종료하기, 회원가입하기, 이메일 사용하기등 일반인들이 무시하기 쉽지만 미숙한 사용자에게는 두려운 부분까지 제시하여 좀 더 전문적인 강의를 받을 수 있도록 하였다.

• Smart Structures and Systems
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• 제19권6호
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• pp.601-614
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• 2017

In this work, free vibration analysis of size-dependent functionally graded (FG) nanoplates resting on two-parameter elastic foundation is investigated based on a novel nonlocal refined trigonometric shear deformation theory for the first time. This theory includes undetermined integral variables and contains only four unknowns, with is even less than the conventional first shear deformation theory (FSDT). Mori-Tanaka model is employed to describe gradually distribution of material properties along the plate thickness. Size-dependency of nanosize FG plate is captured via the nonlocal elasticity theory of Eringen. By implementing Hamilton's principle the equations of motion are obtained for a refined four-variable shear deformation plate theory and then solved analytically. To show the accuracy of the present theory, our research results in specific cases are compared with available results in the literature and a good agreement will be demonstrated. Finally, the influence of various parameters such as nonlocal parameter, power law indexes, elastic foundation parameters, aspect ratio, and the thickness ratio on the non-dimensional frequency of rectangular FG nanoscale plates are presented and discussed in detail.

• Steel and Composite Structures
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• 제30권6호
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• pp.603-615
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• 2019

In the present work, free vibration of beams made of imperfect functionally graded materials (FGMs) including porosities is investigated. Because of faults during process of manufacture, micro voids or porosities may arise in the FGMs, and this situation causes imperfection in the structure. Therefore, material properties of the beams are assumed to vary continuously through the thickness direction according to the volume fraction of constituents described with the modified rule of mixture including porosity volume fraction which covers two types of porosity distribution over the cross section, i.e., even and uneven distributions. The governing equations of power law FGM (P-FGM) and sigmoid law FGM (S-FGM) beams are derived within the frame works of classical beam theory (CBT) and first order shear deformation beam theory (FSDBT). The resulting equations are solved using separation of variables technique and assuming FG beams are simply supported at both ends. To validate the results numerous comparisons are carried out with available results of open literature. The effects of types of volume fraction function, beam theory and porosity volume fraction, as well as the variations of volume fraction index, span to depth ratio and porosity volume fraction, on the first three non-dimensional frequencies are examined in detail.

• Structural Engineering and Mechanics
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• 제60권4호
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• pp.547-565
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• 2016

In this work a new 3-unknown non-polynomial shear deformation theory for the buckling and vibration analyses of functionally graded material (FGM) sandwich plates is presented. The present theory accounts for non-linear in plane displacement and constant transverse displacement through the plate thickness, complies with plate surface boundary conditions, and in this manner a shear correction factor is not required. The main advantage of this theory is that, in addition to including the shear deformation effect, the displacement field is modelled with only 3 unknowns as the case of the classical plate theory (CPT) and which is even less than the first order shear deformation theory (FSDT). The plate properties are assumed to vary according to a power law distribution of the volume fraction of the constituents. Equations of motion are derived from the Hamilton's principle. Analytical solutions of natural frequency and critical buckling load for functionally graded sandwich plates are obtained using the Navier solution. The results obtained for plate with various thickness ratios using the present non-polynomial plate theory are not only substantially more accurate than those obtained using the classical plate theory, but are almost comparable to those obtained using higher order theories with more number of unknown functions.

• 한국표면공학회지
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• 제46권1호
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• pp.22-28
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• 2013

$WS_2$ particles were added to micro-diamond blades with Cu/Sn binding metal as lubricants to improve cutting efficiency. It was found in previous works that the added $WS_2$ lubricant could reduce remarkably the momentary energy consumption during dicing tests but increased wear rate slightly owing to weak bonding between lubricant particles and bond metals. In the present work, the surface of $WS_2$ lubricant particles were etched for activating the surface of $WS_2$ particles that provide even distribution of particles during powder mixing process and improvement of wetting at the interfaces between $WS_2$ particles and molten Cu/Sn bond metals during pressurized sintering so that could provide the improved strength of micro-blades and result in extended life. Chipping behavior of workpiece with the types of micro-blades including $WS_2$ were compared because it is important in semiconductor and micro-packaging industries to control average roughness and straightness of sliced surface which is closely related with quality.

• Journal of the Korean Wood Science and Technology
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• 제46권4호
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• pp.309-314
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• 2018

Size reduction is an important pre-processing operation for utilizing biomass as a sustainable resource in industrial-scale energy production and as a raw material for other industries. This work investigates the size reduction characteristics of air-dried Miscanthus sacchariflorus Goedae-Uksae 1 (Amur silver grass) via image processing and identifies the morphological characteristics of comminuted and screened M. sacchariflorus. At chopping lengths of 18, 40, 80, and 160 mm, 81%, 77%, 78%, and 76% of the particles, respectively, passed through a 4-mm sieve. Even a knife mill with a very small screen aperture (>1 mm) admitted over 10% of the particles. The average circularity and aspect ratio of the particles were <0.30 and >10, respectively. These results confirm that in all preparation modes, most M. sacchariflorus particles were needle-like in shape, irrespective of the type of preparation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1117-1120
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• 2001

Chemical mechanical planarization(CMP) has emerged as the planarization technique of choice in both front-end and back-end integrated circuit manufacturing. Conventional CMP process utilize a polyurethane polishing pad and liquid chemical slurry containing abrasive particles. There have been serious problems in CMP in terms of repeatability and defects in patterned wafers. Since IBM's official announcement on Copper Dual Damascene(Cu2D) technology, the semiconductor world has been engaged in a Cu2D race. Today, even after~3years of extensive R&D work, the End-of-Line(EOL) yields are still too low to allow the transition of technology to manufacturing. One of the reasons behind this is the myriad of defects associated with Cu technology. Especially, dishing and erosion defects increase the resistance because they decrease the interconnection section area, and ultimately reduce the lifetime of the semiconductor. Methods to reduce dishing & erosion have recently been interface hardness of the pad, optimization of the pattern structure as dummy patterns. Dishing & erosion are initially generated an uneven pressure distribution in the materials. These defects are accelerated by free abrasive and chemical etching. Therefore, it is known that dishing & erosion can be reduced by minimizing the abrasive concentration. Minimizing the abrasive concentration by using Ce$O_2$ is the best solution for reducing dishing & erosion and for removal rate. This paper introduce dishing & erosion generating mechanism and a method for developing a semi-rigid abrasive pad to minimize dishing & erosion during CMP.

• The Journal of Asian Finance, Economics and Business
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• 제9권10호
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• pp.115-127
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• 2022

The study's goal was to investigate the levels of employee loyalty (EL) in two Thai railway rolling stock maintenance (RRSM) companies. Simple random sampling was used to obtain a final sample of 118 individuals from October 2021 through December 2021. The research instrument was a questionnaire with an expert IOC value between 0.67 to 1.00 and a questionnaire reliability Alpha (𝛼) average value of 0.82. Descriptive statistics included the mean and standard deviation (SD). SPSS for Windows Version 21 and Multiple Regression Analysis (MRA) was used for the analysis. Results showed that the 118 employee's overall perceptions of their RRSM employers' motivating factors, human resource management, satisfaction, and loyalty were high. HRM's performance evaluation had the most significant overall influence on EL. Moreover, from the analysis of the five EL questionnaire items, the most influential item was the employee's income as a contributing factor to their EL. This was followed by the suitability of their work. Also, it seems the employees had a high level of loyalty to their firms even if a better offer of more money was made. They also indicated a high level of pride in their respective firms.