• Korean Journal of Materials Research
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• v.14 no.10
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• pp.737-742
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• 2004

$CuInSe_2$ (CIS) nanoparticles of chalcopyrite structure were directly synthesized by a solvothemal method in an autoclave with diethylamine as a solvent. A morphology change of the nanoparticles was observed as a function of reaction temperatures and times. Dense rod-type CIS nanoparticles with width of $5\sim10mm$ and length in the range of 30-80 nm were obtained at $180^{\circ}C$ for 36 hrs whereas spherical particles with diameter in the range of 5-10 nm were observed at $250^{\circ}C$ for 36 hrs. The formation of the rod-like nanoparticles in diethylamine, without double N-chelation, was explained by the Solution-Liquid-Solid (SLS) mechanism.

• Korean Journal of Materials Research
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• v.15 no.3
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• pp.189-194
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• 2005

[ $SiO_2$ ] nanowires were synthesized using the catalyst evaporation method. Grown nanowires had different shapes by kind of used metal catalyst. Mean diameters of grown $SiO_2$ nanowire were about 30 nm. The kind of catalysts affected microstructure of grown $SiO_2$ nanowire because of its typical growth reactions through the liquid state metal catalysts. Optical property were measured by photoluminescence spectroscopy. Relatively broad peak was obtained and mean peak positioned at 450 nm.

• Journal of Korean Academy of Nursing
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• v.36 no.2
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• pp.361-372
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• 2006

Purpose: This paper was conducted to examine the effects of transformational leadership behaviors, within the substitutes for leadership model(Kerr & Jermier, 1978). Method: Data was collected from 181 staff nurses in 3 general hospitals, with self-reporting questionnaires(MLQ developed by Bass, rd-SLS developed by Podsakoff, et at., and MSQ developed by Weiss, et al.). Descriptive statistics, factor analysis, Cronbach's alpha and moderated regression analysis were used. Result: 1) The transformational leader behaviors and substitutes for leadership each had correlations with job satisfaction. 2) The total amount of variance accounted for by the substitutes for leadership was substantially greater than by the transformational leadership behaviors. 3) Few of the substitutes variables moderated the relationships between the transformational leader behaviors and job satisfaction in a manner consistent with that specified by Howell, Dorfman, and Kerr(1986). Conclusion: The finding of this study suggest that leaders need to have a better understanding of those contextual variables that influence job satisfaction. Thus future research should focus attention on the moderating effects of substitutes, as well as the things that leaders can do to influence them. In addition, it may be good to examine the effects of substitutes on other criterion variables.

• Korean Journal of Computational Design and Engineering
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• v.2 no.1
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• pp.35-43
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• 1997

Concurrent Engineering is one of the methods which are used for the rapid product development. One of the important features in Concurrent Egineering is that the development process is to be parallel and the organization should be cross-functional. In order that the process be parallel and that the organization be cross-functional, an integrated information system such as PDM (Product Data Management) is required. Although the integrated data base is constructed, it could be meaningless if the application softwares were not inter-operable. This study shows an example of intergrated information system from three-dimensional product design to mold design and tooling for the development of Deflection Yoke(DY) which is one of the important parts of Cathode Ray Tube(CRT). A three-dimensional product design software, which is based on a commercial code, has been developed by ourselves. Selective Laser Sintering(SLS), which is one of the rapid prototyping techniques, has been used in this study. Mold design has been done by the three-dimensional way. A newly developed method of mold tooling, which is called Quick Die Manufacturing(QDM), has been introduced.

• ETRI Journal
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• v.21 no.4
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• pp.65-82
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• 1999

We present a calculation model for an improved quantitative theoretical analysis of electronic and optical properties of strained-piezoelectric[111] InGaAs/GaAs superlattices (SLs). The model includes a full band-coupling between the four important energy bands: conduction, heavy, light, and spin split-off valence bands. The interactions between these and higher lying bands are treated by the k ${\cdot}$ p perturbation method. The model takes into account the differences in the band and strain parameters of constituent materials of the heterostructures by transforming it into an SL potential in the larger band-gap material region. It self-consistently solves an $8{\times}8$ effective-mass $Schr{\ddot{o}}dinger$ equation and the Hartree and exchange-correlation potential equations through the variational procedure proposed recently by the present first author and applied to calculate optical matrix elements and spontaneous emission rates. The model can be used to further elucidate the recent theoretical results and experimental observations of interesting properties of this type of quantum well and SL structures, including screening of piezoelectric field and its resultant optical nonlinearities for use in optoelectronic devices.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.3
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• pp.21-26
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• 2015

Many 3D printing technologies are being used in various industries, and their demands for well-educated engineers are increasing. Moreover, novel technologies are being developed to overcome the limits of existing 3D printing technologies. In this regard, adequate education and a related curriculum especially in the Mechanical Engineering field, which is the basis of the industry, is essential. In this paper, the development of the 3D printing curriculum and its assessment in Mechanical Engineering education are proposed. The education program consisted of lectures and practice. It consisted of major 3D printing technologies, such as SLA, FDM, SLS, LOM, and Polyjet. Moreover, post-processing, room temperature vulcanizing (RTV), and coloring were also taught. The effectiveness of the proposed education program was assessed by the questionnaire survey, and the results were analyzed. Areas of improvement were deduced from the survey results.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.3
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• pp.356-359
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• 2000

The study was conducted to evaluate the nutritional value of seeds and various seed fractions of different varieties of cotton (MNH 147, CIM 240, NIAB 78, FH 87, CIM 109, MNH 93, FH 682, GOHAR 87, SLS I and B 557). Linter, hull, kernel and meal were obtained from cottonseed by physical and chemical methods. Free gossypol and available lysine contents of seed and it's fractions were determined. In vitro protein digestibility of cottonseed meal was also determined. Free gossypol and available lysine contents ranged between 0.22-2.26% and 0.64-1.32% in seed, and 0.03-0.29% and 1.38-2.36% in meal, respectively. FH 87 was highest both in free gossypol and available lysine content, and NIAB 78 was lowest in free gossypol content and FH 862 was lowest in available lysine content. In vitro protein digestibility of cottonseed meal ranged between 66,02-79,96%. Statistical analysis revealed significant (p<0.05) varietal differences in free gossypol, available lyslne and in vitro protein digestibility of cottonseed and derived products.

• International Journal of CAD/CAM
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• v.3 no.1_2
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• pp.85-95
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• 2003

During the design of dies and molds, the cavity of the object is obtained by subtracting it from a surrounding rectangular block. This box is subsequently split into two halves by the parting surface. Similar problems also occur in some RP processes such as LOM, SGC, SLS and 3DP where the machine produces a block inside which the prototype is buried. Determining the orientation of the object inside the box and the corresponding parting surface taking appropriate constraints into account have been addressed by several researchers. However, given the parting surface, the problem of splitting the box development of a software package called OptiLOM (now a module of an RP software Magics 8.0), the authors realized non-triviality of this problem since the loop can spread over as many as 5 faces of the box. In this paper, the authors have tried to bring out the importance of this problem and have presented their algorithm to solve it.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.824-828
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• 2000

As production cycle has become more and more shorter, the demand of rapid prototyping technology has increased largely. There are many methods for rapid prototyping technology, such as SLA. SLS, FDM. INK JET, LOM and so on. Of all methods, SLA has been most widely used for fabricating precision parts. But products manufactured by this method have limitation of single color and single material. So the principal purpose of this study is to overcome the limit of single color product. If the internal structure of manufactured product is visible with multi-color characteristic, it is possible to check easily the designed model with reality. In order to give multi-color characteristic to the product, photocurable resin mixed with pigment is used in this study. First, transparency of photocurable resin without pigment is evaluated, and then color characteristic and curing characteristic of the mixture is evaluated changing mixing ratio. Through the basic experiments, it becomes possible to fabricate multi-color 3D prototype without assembly.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.183-190
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• 2006

Digital 3D Real Object Duplication System (RODS) consists of 3D Scanner and Solid Freeform Fabrication System (SFFS). It is a device to make three-dimensional objects directly from the drawing or the scanning data. In this research, we developed an office type SFFS based on Three Dimensional Printing Process and an industrial SFFS using Dual Laser. An office type SFFS applied sliding mode control with sliding perturbation observer (SMCSPO) algorithm for control of this system. And we measured process variables about droplet diameter measurement and powder bed formation etc. through experiments. In case of industrial type SFFS, in order to develop more elaborate and speedy system for large objects than existing SLS process, this study applies a new Selective Dual-Laser Sintering (SDLS) process and 3-axis Dynamic Focusing Scanner for scanning large area instead of the existing f lens. In this process, the temperature has a great influence on sintering of the polymer. Also the laser parameters are considered like that laser beam power, scan speed, and scan spacing. Now, this study is in progress to evaluate the effect of experimental parameters on the sintering process.