• Journal of Engineering Education Research
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• v.24 no.1
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• pp.46-52
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• 2021

The purpose of this study is to clarify that critical writing can be a positive stimulus factor for the cultivation of critical thinking through actual cases of writing education targeting engineering students in universities. Critical writing education is a very important way to develop critical thinking necessary for acquiring scientific knowledge, sharing social values, creativity and cultivating new production capacity. Especially, when critical writing education is performed with materials that maintain critical view of social reality such as the movie "Bowling for Columbine", it is characterized by the fact that it is naturally combined with the dimension of engineering ethics faced by engineers from the analysis and judgment of social reality. This is an example of the fact that critical thinking education for engineering students does not necessarily meet their major areas.

• The KSFM Journal of Fluid Machinery
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• v.14 no.6
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• pp.91-95
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• 2011

This paper deals with the detail rotordynamic analysis for the assembly rotor composed of turbine wheel, turbine shaft, connecting arbor, and flange & spindle in order to perform the spin test of turbocharger turbine. Prior to rotordynamic analysis, the 1st spin test was performed but the test was failed by excess vibration in the neighborhood rated speed. It is the reason for this fail that the separation margin between the rated speed and critical speed is not enough, confirmed by rotordynamic analysis results. Since then, the dimension of turbine shaft was modified and the critical speeds were again reviewed for modified assmebly rotor. In results, the separation margin between the rated speed and critical speed is over 20% and then the 2nd spin test was performed successfully. In preparing spin test for turbine, compressor wheels and etc., the geometry design of connecting arbor and dimension of rough machining should be reviewed by considering rotordynamic results, and the separation margin should be enough for successful spin test.

• Proceedings of the Korea Association of Information Systems Conference
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• 2004.11a
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• pp.431-443
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• 2004

Many e-Learning companies are incorporated for the last five years, but most of them are failed or merged by the other company. The main reasons are the absence of competitive strategies and recognition of critical success factors. There are many researches on the critical success factors of Information System (IS) and Electronic Commerce (EC) . We derived e-Learning success factors from the previous IS and EC researches. We classified the success factors into five dimensions, (1) contents management, (2) learner management, (3) business strategy, (4) organizational support and ability, (5) learning management system (LMS), and each dimension has 9 or more success factors measurement items. We surveyed the perceived importance of the success factors from the manager of South Korea e-Learning firms. The paper categorized the items into two or more factors for each dimension by the exploratory factor analysis. Finally, we conducted one-way ANOVA for each success factors by the business model. As a result, there is different importance level for each success factors by the business model. We concluded that each e-Learning company needs different strategies to their business model.

• Current Optics and Photonics
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• v.2 no.2
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• pp.153-164
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• 2018

In semiconductor manufacturing, critical dimensions indicate the features of patterns formed by the semiconductor process. The purpose of measuring critical dimensions is to confirm whether patterns are made as intended. The deposition process for an organic light emitting diode (OLED) forms a luminous organic layer on the thin-film transistor electrode. The position of this organic layer greatly affects the luminescent performance of an OLED. Thus, a system for measuring the position of the organic layer from outside of the vacuum chamber in real-time is desired for monitoring the deposition process. Typically, imaging from large stand-off distances results in low spatial resolution because of diffraction blur, and it is difficult to attain an adequate industrial-level measurement. The proposed method offers a new superresolution single-image using a conversion formula between two different optical systems obtained by a deep learning technique. This formula converts an image measured at long distance and with low-resolution optics into one image as if it were measured with high-resolution optics. The performance of this method is evaluated with various samples in terms of spatial resolution and measurement performance.

• Korean Journal of Optics and Photonics
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• v.18 no.1
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• pp.74-78
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• 2007

We report theoretical and experimental results for application of transmittance-controlled photomask technology to ArF lithography. The transmittance-controlled photomask technology is thought to be a promising technique fo critical dimension (CD) uniformity correction on a wafer by use of phase patterns on the backside of a photomask. We could theoretically reproduce experimental results for illumination intensity drop with respect to the variation of backside phase patterns by considering light propagation from the backside to the front side of a photomask at the ArF lithography wavelength. We applied the transmittance-controlled photomask technology to ArF lithography for a critical layer of DRAM (Dynamic Random Access Memory) having a 110-nm design rule and found that the in-field CD uniformity value was improved from 13.8 nm to 9.7 nm in $3{\sigma}$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.319-324
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• 2003

In general industrial rotating machinery is operated under 3,600 rpm as rotating speed and designed to have critical speed that is above operating speed. So, there was no problem to operate rotating machine under critical speed. But nowadays, they should be operated more than the frist critical speed as usual with the trend of high speed, large scale and hish precision in industries. In case of the large rotor assembly as the trend of large scale, using fitting method of disk or cylinder on shaft is rising for the convenience of assembly and cutting down of manufacturing cost. The shrink fitting is used to assemble lamination part on shaft for manufacturing of rotor of motor or generator in many cases and also is widely used for other machinery. In rotating system, which is compose of rotor and bearing, the critical speed is determined from inertia and stiffness for the rotor and bearings. In case of fitting assembly, analysis and design of the rotor is not easy because the rotor stiffness is determined depend on a lot of factors such as shaft material/dimension, disk material/dimension and assembled interference etc. Therefore designer who makes a plan for hish-speed rotating machine should design that the critical speed is located out of operating range, as dangerous factors exist in it. In order to appropriate design, an accurate estimation of stiffness and damping is very important. The stiffness variation depend on fitting interference is a factor that changes critical speed and if it's possible to estimate it, that Is very useful to design rotor-bearing system. In this paper, the natural frequency variation of the rotor depends on fitting interference between basic shaft and cylinder is examined by experimentation. From the result, their correlation is evaluated quantitatively using numerical analysis that is introduced equivalent diameter end the calculation criteria is presented for designer who design fitting assembly to apply with ease for determination of appropriate interference.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.6.1-6.1
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• 2011

Nanoscale block copolymer (BCP) patterns have been pursued for applications in sub-30 nm nanolithography. BCP self-assembly processing is scalable and low cost, and is well-suited for integration with existing semiconductor fabrication techniques. However, one of the major technical challenges for BCP self-assembly is limited tunability in pattern geometry, dimension, and functionality. We suggest methods for extending the degree of tunability by choosing highly incompatible polymer blocks and utilizing solvent vapor treatment techniques. Siloxane BCPs have been developed as self-assembling resists due to many advantages such as high etch-selectivity, good etch-resistance, long-range ordering, and reduced line-edge roughness. The large incompatibility leads to extensive degree of pattern tunability since the effective volume fraction can be easily manipulated by solvent-based treatment techniques. Thus, control of the microdomain size, periodicity, and morphology is possible by changing the vapor pressure and the mixing ratio of selective solvents. This allows a range of different pattern geometry such as dots, lines and holes and critical dimension simply by changing the processing conditions of a given block copolymer without changing a polymer chain length. We demonstrate highly extensive tunability (critical dimension ~6~30 nm) of self-assembled patterns prepared by a siloxane BCP with extreme incompatibility.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.228-229
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• 2009

$VO_2$ thermistor was fabricated on $Al_2O_3$ substrate. and has a CTR (Critical Temperature Resistor) characteristic. $VO_2$ thermistor has a about $10^6$ resistance($\Omega$) in normal temperature. But When temperature is a about $80^{\circ}C$, Resistance of $VO_2$ thermistor is a about some hundred resistance: The resistance of $VO_2$ thermistor increased with increasing length and decreasing width.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.515-521
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• 2003

There are now many theoretical investigations and real manufactures for numerous applications of photonic crystals (PCs) associated with photonic band gap and photonic integrated circuits. However, there are some difficulties to design and fabricate the desired pattern quality. It is not easy to satisfy accurate critical dimension (CD) for patterns with arbitrary shapes and pitch sizes aligned in various directions. In this work, we report the optimum conditions to better fabricate and design, and greatly improve pattern quality in delineating two-dimensional (2D) PCs in the nanometer range using single- step e-beam lithography system with conventional exposure mode.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.11
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• pp.1014-1021
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• 1998

We evaluated the effect of processing variables on microstructural evolution interface irregularity between Ag sheath and superconductor core and resultant critical current density(J$_{c}$) of (Bi,Pb)$_2$Sr$_2$Ca$_2$Cu$_3$O$_{x}$(2223) superconductor tape. The value of J$_{c}$ was significantly influenced by the interface irregularity, degree of texturing and relative 2223 content. The interface became more irregular(sausage effect), while the degree of texturing gradually improved as the dimension of tape decreased during forming process. As the dimension of wire/tape were changed from diameter of 3.25 mm to thickness of 0.20 mm, J$_{c}$ value was observed to be increased by 10 times. In addition, optimum sintering temperature for improved J$_{c}$ was observed to be 835$^{\circ}C$ in a ambient atmosphere probably due to combined effect of both improved texturing and high 2223 content. Microstructural investigation showed the degree of texturing was degraded by the existence of both second phases and interface irregularity. It was observed that larger grain size and better texturing was developed near relatively flat interface compared to those inside superconducting core.ting core.