• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.65-70
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• 2009

In this paper a hybrid grid generation program for general 2-D region is introduced. The program is developed by using JAVA programming language, and it can be used either as an application program on a local computer or as an applet in the network environment. The hybrid grid system for a 2-D problem means a combination of triangular cells and quadrilateral cells, and it can offer both of the high flexibility of triangular cells and the high accuracy and efficiency of structured-type quadrilateral cells. To accommodate a quadrilateral-cell region and a triangular-cell region into one computational domain, it is importance to take good care of the interface between two different regions so that overall good grid quality can be maintained. In this research advancing layer method(ALM) augmented by elliptic smoothing method is used for the quadrilateral-cell region and advancing front method(AFM) is used for the triangular-cell region. A special treatment technique for the interface between those two regions is also developed. The interface treatment technique is basically to prevent the propagation of small cell size due to ALM method into the triangular region and maintain the smooth transition of cell-size scale between two different regions. By applying current technique high-quality hybrid grids for general 2-D regions can be easily generated, and typical grid generation results and flow solutions are demonstrated.

• Korean Journal of Human Ecology
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• 제22권2호
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• pp.365-374
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• 2013

The purposes of this study were to evaluate the color characteristics and color sensibility of mulberry/cotton blended fabrics dyed with indigo, the natural dye, and analyze effects of them on color preferences. The values of CIE $L^*$, $a^*$, $b^*$ $C^*$, h were calculated for the color characteristics of indigo-dyed fabrics, and their hue, value, and chroma were calculated according to the Munsell color system. Fifty male and female college students evaluated the color sensibility of nine types fabrics dyed with indigo on a seven-point scale. The data were analyzed by descriptive statistics, factor analysis, Kruscal-Wallis test, correlation analysis, and regression analysis. The mulberry/cotton blended fabrics naturally dyed with indigo showed the characteristics of PB color tones, low value, and low chroma. The color sensibilities of fabrics dyed with indigo were classified into four factors: 'classic', 'sporty', 'elegant' and 'natural'. There were significant differences according to the fibers and the repeating times of dyeing in the color sensibility for the fabrics. Cotton fabrics were evaluated to be more classic, sporty, elegant, and natural than the mulberry/cotton blended fabrics, and the deeper the color, the more classic, sporty, and elegant the fabric was evaluated. The students preferred the indigo dyed fabrics which have more classic, sporty, and natural sensibility. There were significant relationships between the color sensibilities and colorimetric properties of the fabrics dyed with indigo. The color preferences of the dyed fabrics with indigo were found to be influenced by the 'classic', 'sporty', 'natural' of color sensibility.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권1호
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• pp.10-15
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• 2003

This paper presents the digital computer performance evaluations of the three-phase self-excited induction generator (SEIG) driven by the variable speed prime mover such as the wind turbine using the nodal admittance approach steady-state frequency domain analysis with the experimental results. The three-phase SEIG setup is implemented for small-scale rural renewable energy utilizations. The experimental performance results give a good agreement with those ones obtained from the digital computer simulation. Furthermore, a feedback closed-loop voltage regulation of the three-phase SEIG as a power conditioner which is driven by a variable speed prime mover employing the static VAR compensator (SVC) circuit composed of the thyristor phase controlled reactor (TCR) and the thyristor switched capacitor(TSC) is designed and considered herein for the wind-turbine driven the power conditioner. To validate the effectiveness of the SVC-based voltage regulator of the terminal voltage of the three-phase SEIG, an inductive load parameter disturbances in stand-alone are applied and characterized in this paper. In the stand-alone power utilization system, the terminal voltage response and thyristor triggering angle response of the TCR are plotted graphically. The simulation and the experimental results prove the effectiveness and validity of the proposed SVC which is controlled by the Pl controller in terms of fast response and high performances of the three-phase SEIG driven directly by the rural renewable energy utilization like a variable-speed prime mover.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.405-406
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• 2006

Recently, the flat display modules such as plasma or TFT-LCD employ thin crystallized panels which are normally weak to high level transient mechanical energy inputs. As a result, anti-shock performance is one of the most important design specifications for TFT-LCD modules. However, most of large display module designs are generated based on engineers own experiences. Also, a large-scale analysis to evaluate complex material and structural behaviors is one of interesting topic in diverse engineering and scientific fields. The utilization of massively parallel processors has also been a recent trend of high performance computing. The objective of this paper is to introduce a parallel process system which consists of general purpose finite element analysis solver as well as parallelized PC cluster. The parallel processing system is constructed using thirty-two processing elements and the finite element program is developed by adopting hierarchical domain decomposition method. In order to verify the efficiency of the established system, an impact analysis on thin and complex sub-parts of flat display modules is performed. The evaluation results showed a good agreement with the corresponding reference solutions, and thus, the parallel process system seems to be a useful tool fur the complex structural analysis such as IT related products.

• Journal of The Korean Society of Agricultural Engineers
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• 제59권3호
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• pp.29-39
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• 2017

In this study, the GPM (Global Precipitation Mission) IMERG (Integrated Multi-satellitE retrievals for GPM) rainfall data was verified and evaluated using ground AWS (Automated Weather Station) and radar in order to investigate the availability of GPM IMERG rainfall data. The SPI (Standardized Precipitation Index) was calculated based on the GPM IMERG data and also compared with the results obtained from the ground observation data for the Hoengseong Dam and Yongdam Dam areas. For the radar data, 1.5 km CAPPI rainfall data with a resolution of 10 km and 30 minutes was generated by applying the Z-R relationship ($Z=200R^{1.6}$) and used for accuracy verification. In order to calculate the SPI, PERSIANN_CDR and TRMM 3B42 were used for the period prior to the GPM IMERG data availability range. As a result of latency verification, it was confirmed that the performance is relatively higher than that of the early run mode in the late run mode. The GPM IMERG rainfall data has a high accuracy for 20 mm/h or more rainfall as a result of the comparison with the ground rainfall data. The analysis of the time scale of the SPI based on GPM IMERG and changes in normal annual precipitation adequately showed the effect of short term rainfall cases on local drought relief. In addition, the correlation coefficient and the determination coefficient were 0.83, 0.914, 0.689 and 0.835, respectively, between the SPI based GPM IMERG and the ground observation data. Therefore, it can be used as a predictive factor through the time series prediction model. We confirmed the hydrological utilization and the possibility of real time drought monitoring using SPI based on GPM IMERG rainfall, even though results presented in this study were limited to some rainfall cases.

• Journal of Engineering Education Research
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• 제17권3호
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• pp.51-58
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• 2014

The main objective of this research lies in estimating how much importance the educators of professional general education and MSC curriculum put on assessment, and, thereafter, take what support should be provided for the efficient assessment of education. The subjects of this research are educators of professional general education and MSC curriculum in the engineering education enrichment program at the 58 universities out of 72 universities where the accreditation for engineering education is implemented. Accordingly questionnaires were distributed to a total of 58 universities among which 136 questionnaires were collected. The data analysis methods, mean and response sample T test, were used in this research. The following conclusions were drawn from the results of this research. First, tile mean of importance and performance in the 'assessment activities' were relatively high. However, in tile assessment, the assessment performance was relatively lower than the assessment importance. Second, the results of the Importance-Performance Matrix in the 'assessment activities' was analyzed by two ways. First, Analyzed with the scale mean, The result means that Keep up the Good Work (KGW) sector included all factors. Second, Analyzed with the actual mean, The result means that KGW sector included 5 factors A, J, B, D, C. Possible Overkill(PO) sector included factors C, I. Low Priority(LP) sector included 4 factors K, E, H, L. Concentrate Here (CH) sector included factor G.

• Journal of Korean society of Dental Hygiene
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• 제14권4호
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• pp.485-493
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• 2014

Objectives : The study investigated and analyzed the relationship between health-related lifestyle and psychosomatic self-reported symptom in dental hygiene students. Methods : A self-reported questionnaire was filled out by 478 dental hygiene students in Gyeonggi-do and Gangwon-do from March 7 to June 21, 2012 by random sampling method after informed consent. Results : The health-related lifestyle showed the results as follows. Nonsmokers accounted for 89.1%. Those who never exercise accounted for 67.9% and 37.9% of the students sleep for 5-6 hours. Those who take alcohols twice per month accounted for 58.2%. The correlation between the symptoms and lifestyle included multiple subjective symptoms(I), respiratory(A), eyes and skin(B) and digestive organs(C) symptoms and smoking status(p<.01), mouth and anal(D), depression(K), nervousness(E). There existed the correlation in average sleeping time(p<.01) and impulsivess(H) and smoking status(p<.05) and lie scale(L) and regular exercise(p<.05) and aggressiveness(F) and drinking habits and irregular and life(G) and breakfast habits. The smoking habit, sleeping time, and snack intake had an influence on psychosomatic self-reported oral health-related symptoms. Conclusions : Cessation of smoking, adequate sleeping time, and reduction of snack intake can improve the oral health-related lifestyle and reduce the self-reported symptoms in the dental hygiene students.

• Journal of the Korean Ceramic Society
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• 제40권10호
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• pp.936-942
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• 2003

In order to develop glass formulations for vitrifying Low-and Intermediate-Level radioactive Wastes (LILW) from nuclear power plants of Korea Hydro & Nuclear Power (KHNP) Co., Ltd., promising glass formulations were selected based on glass property model predictions for viscosity, electrical conductivity and leach resistance. Laboratory measurements were conducted to verify the model predictions. Based on the results, the models for electrical conductivity, US DOE 7-day Product Consistency Test (PCT) elemental release, and pH of PCT leachate are accurate for the LILW glass formulations. However, the model for viscosity was able to provide only qualitative results. A leachate conductivity test was conducted on several samples to estimate glass leach resistance. Test results from the leachate conductivity test were useful for comparison before PCT elemental release results were available. A glass formulation K11A meets all the KHNP glass property constraints, and use of this glass formulation on the pilot scale is recommended. Glass formulations K12A, K12B, and K12E meet nearly all of the processing constraints and may be suitable for additional testing. Based on the comparison between the measured and predicted glass properties, existing glass property models may be used to assist with the LILW glass formulation development.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.396-401
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• 2004

In this paper, a 1MW HAWT(FIL-1000) rotor blade has been designed by BEMT(Blade Element Momentum Theory) with Prandtl's tip loss. Also, a 3-D flow and performance analysis on the FIL-1000 rotor blade has been carried out by using the 3-D Navier-Stokes commercial solver (CFX-5.7) to provide more efficient design techniques to the large-scale HAWT engineers. The rated power and itsapproaching wind velocity at design point (TSR=7.5) are 1MW and 9.99m/s respectively. The rotor diameter is 54.5m and the rotating speed is 26.28rpm. Airfoils such as FFA W-301, DU91-W-250, DU93-W-210, NACA 63418, NACA 63415 consist of the rotor blade from hub to tip. Recent CFX version, 5.7 was adopted to simulate 3-D flow field and to analyze the performance characteristics of the rotor blade. Entire mesh node number is about 730,000 and it is generated by ICEM-CFD to achieve better mesh quality The predicted maximum power occurringat the design tip speed ratio is 931.45kW. Approaching to the root, the inflow angle becomes large, which causesthe blade to be stalled in the region. Therefore, k-$\omega$ SST turbulence model was used to predict the quantitative flow information more accurately. Application of commercial CFD code to optimum blade design and performance analysis was proved to be more effective environment to HAWT blade designers.

• Journal of the Society of Cosmetic Scientists of Korea
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• 제24권3호
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• pp.51-58
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• 1998

Generally pigment differs from dye stuff because it cannot be melted in water but also because it is stable physically and chemically. In this study you will discover the function, properties and effects of Micai-TiO$_2$-SiO$_2$pigment as abase material pigment. But until now used Mica of the base material is about 7-l5${\mu}{\textrm}{m}$ with an average diameters of 15${\mu}{\textrm}{m}$. A new characteristic superficial pigment was obtained from covering the TiO$_2$ and SiO$_2$ with the adsorption result of isoelectric point of a Mica flake, TiO$_2$ and SiO$_2$In the composition reaction study of adsorption was done as well as the physical characteristics of the superficial texture of the obtained material. L,a,b of color change as oil was absorbed, optical nature and change of reflection according to direct and diffused reflection. In the composition of Mica slurry the best result obtained was in a solution with pH 2.0 to 2.3. Following this result, we can come to the idea that electrical attraction was done during the change of electrical charge of the Mica and TiO$_2$ deposit. Also this pigment shows a big scale between the direct reflection and diffused reflection light. Using this characteristic in cosmetic, it was obtained a natural but a contrast between light and shadow making possible a sculptured make-up. Color change due to oil adsorption was insignificant which improved the last of make up.