• Proceedings of the Korean Society of Veterinary Clinics Conference
• /
• 2009.04a
• /
• pp.298-298
• /
• 2009

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.1102-1103
• /
• 2006

The pretreatment for substrate was carried out in change of gun pressure of $0.5\sim3.5$ bar using wet blasting. The size of $Al_2O_3$ powder was about $50{\sim}150{\mu}m$. As the results, the surface roughness of cemented carbide substrate was improved with increment of gun pressure of wet blasting. A new surface layer was formed and Co particles were uniformly distributed over the entire surface after pretreatment. The adhesion of the pretreated substrate in same PVD-TiAlN film was improved and in approximately $Ra=90\sim120\;nm$ shown the best adhesion value.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.18 no.1
• /
• pp.22-28
• /
• 2009

In order to optimize the polishing process, Run to Run control scheme has been applied to the micro mold polishing in this study. Also, to fully understand the effect of parameters on the surface roughness a design of experiment is performed. By linear approximation of main factors such as gap and rotational speed of micro quill, EWMA (Exponential Weighted Moving Average) gradual mode controller is adopted as a optimizing tool. Consequently, the process converged quickly at a target value of surface roughness Ra 10nm and Rmax 50nm, and was hardly affected by unwanted process noises like initial surface quality and wear of magnetic abrasives.

• Proceedings of the KIEE Conference
• /
• 2002.11a
• /
• pp.13-15
• /
• 2002

The trench MOSFET structure is characterized by reduced on-resistance due to elimination of $R_{JFET}$ and high packing density. An analytical calculation of Ron as the sum of $R_{ch}$ and $R_{epi}$ has been reported previously for the trench MOSFET structure. However, the accumulation layer resistance may not be neglected for Trench MOSFET especially for a relatively large value of the cell spacing, where a major contribution to Ron comes from Ra as the simulation results in this paper shows.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.3
• /
• pp.1114-1122
• /
• 1996

Variation of temperature field in a Hele-Shaw convection cell was measured by using a HSI true color image processing system and TLC(Thermochromic Liquid Crystal) solution. The relationship between the hue value of TLC color image and real temperature was obtained and this calibration result was used to measure the true temperature. The temperature field in the Hele-Shaw convection cell shows periodic characteristics of 45 sec at Ra = 9.3 * 10$\^$6/. The temperature field measurement technique developed in this study was proved to be a useful and powerful tool for analyzing the unsteady thermal fluid flows.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.542-545
• /
• 2004

The vibration reduction process for the driver comfort of a forklift truck is studied in this study since the related driver comfort is a primary design target in the vehicle design recently. However, the underlying study for a vibration analysis regarding to the driver comfort is still an element stage. Thus, a preceding large work has to be needed to apply the CAE technology for the detail vehicle design, and it prevents the vehicle optimal design. To reduce the proceeding large works, the evaluated process and required data are comply with the accumulated trouble shooting experiences in this study. Since the driver comfort is a human related problem, the human vibration index associated with analysis vibration result is additionally introduced as a driver comfort judgement value.

• Journal of the Korean Society of Industry Convergence
• /
• v.22 no.6
• /
• pp.607-613
• /
• 2019

In this study, we investigate the effect of SNCM616 alloy steel, which is commonly used in industry, such as rotors and crank-shafts, on the surface roughness of CNC HBM with Ø25 mm, 8-blade reamer to objective is to analyze and present optimal cutting conditions. The higher the feedrate for the spindle speed, the rougher the surface roughness. The surface roughness was found to be better when the feed rate was lower. The resultant value of the most accurate surface roughness is Ra 0.756 ㎛, and the optimal cutting conditions are 25 rpm at spindle speed and 20 mm/min at transfer speed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.16 no.3
• /
• pp.211-217
• /
• 2004

Effect of a solid insert on thermal stratification in the natural convection enclosure is numerically investigated. The enclosure consists of two differently heated vertical walls and two adiabatic horizontal walls. A solid insert is located in the middle of the enclosure. The non-dimensional governing equations are solved by using the SIMPLER algorithm. The computations are carried out with the variations of thermal conductivity, width and height of the solid insert. The Prandtl number of the fluid in an enclosure is fixed at Pr=0.71, Two cases of Rayleigh number are considered in the present study, i.e., Ra:10$^3$ and 10$^{6}$ . The thermal stratification attenuates as thermal conductivity, width, and height of the solid insert are increased. As the thermal conductivity ratio of a solid insert to fluid increases beyond (equation omitted)10$^3$, the thermal stratification ratio shows an asymptotic value.

• Journal of Engineering Education Research
• /
• v.21 no.3
• /
• pp.20-30
• /
• 2018

The purpose of this study is to analyze the characteristics of college students majoring in the engineering on career decision difficulties and emotional and personality career difficulties. Data is consisted of 430 college students. We tested the research question by employing the PSM and the multi-regression model. The result showed that college students majoring in the engineering have difficulties in the information about self, the lack of information, and the outside control on career decision more than others. We suggested that career education and counseling of understanding themselves such as interesting, aptitude, and occupational value should be provided for students majoring in the engineering.

• Journal of the Semiconductor & Display Technology
• /
• v.23 no.3
• /
• pp.14-20
• /
• 2024

In this study, TiN thin films, used as electrode thin films, were deposited through the Thermal Atomic Layer Deposition method using TDMAT (Tetrakis(dimethylamido)titanium) as the precursor and NH3 as the reactant. After deposition at various temperatures, the thickness, crystal structure, surface roughness, impurity content, and resistivity of the films were compared. The results showed that the optimal process temperature was 200℃, forming TiO2 anatase and TiN(200) crystal structures. The surface roughness was the lowest, with Ra=0.393nm and Rq=0.502nm, and the impurity content was 27.5% O and 6.35% C, with the resistivity also recording its minimum value. Particularly, at a long pulsed time of 11 seconds, the impurity inclusion due to self-decomposition reactions was dominant, showing excellent properties at lower temperature.