• Korean Journal of Materials Research
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• v.2 no.6
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• pp.428-435
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• 1992

AISI 4600 Iron powder was mixed with 0~1.0% phosphor as F$e_2$P powder and/or 0~0.8% carbon as graphite powder in rotating mixer. Mixed powder was pressed 800MPa in double-punch mould. Compacts were sintered at 115$0^{\circ}C$for 30 min. in vacuum or mixed hydrogen and nitrogen gas. Sintered compacts were ground and polished, and etched by 2% nital etchant. The microstructure was observed by image analyzer and optical microscope. Density and microhardness were tested by ASTM B3l2 and Microvickers hardness tester. The results obtained were as follows : (1) As the amount of F$e_2$P powder increased, sintered microstructure showed more densified effect and the grain size was larger. (2) The shape of pore was rounded and the number of pore was decreased by F$e_2$P addition. But mean pore size was larger with F$e_2$P content. (3) Simultaneous alloying addition of F$e_2$P and graphite brought about larger grain growth than respective addition. (4) Sintering atmosphere did not affect the microstructure. (5) Hardness of sintered compact increased with phosphrous and carbon content.

• East Asian mathematical journal
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• v.4
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• pp.57-73
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• 1988

The subclasses S*($\alpha,\beta,\mu$) and C*($\alpha,\beta,\mu$) ($0\leqq\alpha<1,\;0<\beta\leqq1$ and $0\leqq\mu\leqq1$) of T the class of analytic and univalent functions of the form $$f(z)=z-\sum\limit^{\infty}_{n=2}\mid a_n\mid z^n$$ have been considered. Sharp results concerning coefficients, distortion of functions belonging to S*($\alpha,\beta,\mu$) and C*($\alpha,\beta,\mu$) are determined along with a representation formula for the functions in S*($\alpha,\beta,\mu$). Furthermore, it is shown that the classes S*($\alpha,\beta,\mu$) and C*($\alpha,\beta,\mu$) are closed under arithmetic mean and convex linear combinations. Also in this paper, we find extreme points and support points for these classes.

• Journal of Korean Biological Nursing Science
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• v.18 no.1
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• pp.43-50
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• 2016

Purpose: This study aimed to identify the relationship among knowledge, attitudes and prevention behaviors (PB) on tuberculosis (Tb) infection in nursing students. Methods: 268 subjects were recruited from two universities located in C D cities of Korea and data were collected utilizing self-reported questionnaires. Results: The mean scores of knowledge, attitudes and PB on Tb infection were 64.83, 3.18 and 2.97. The knowledge differed according to gender (t=-3.16, p=.002), grades (F=32.19, p<.001), educational experience about Tb (EETb) (F=10.59, p<.001), learning information about Tb (t=3.08, p=.002) and getting Tb: self or others (t=2.78, p=.006). The attitudes differed according to grades (F=7.71, p<.001) and EETb (F=2.68, p=.047). The PB differed according to grades (F=7.02, p<.001) and EETb (F=4.55, p=.004). Significant correlations were found between knowledge and PB (r=.20, p=001), attitudes and PB (r=.33, p<.001). The most significant factor influencing PB was attitudes with R2 value of 13.9% (F=11.81, p<.001). Conclusion: These findings indicate that knowledge and attitude adjustment may be necessary to improve PB for Tb infection in nursing students. Moreover further study is necessary to find out the ways to reinforce the level of attitudes. The results of the study can be utilized in educational programs for preventing Tb infection in nursing students.

• Journal of Sensor Science and Technology
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• v.16 no.1
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• pp.24-32
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• 2007

Conductive rubber material was molded in a belt shape to measure respiration. Its resistivity was approximately $0.03{\;}{\Omega}m$ and the resistance-displacement relationship showed a negative exponent. The temperature coefficient was approximately $0.006{\;}k{\Omega}/^{\circ}C$ negligible when practically applied on the abdomen. The conductive rubber belt was applied on a normal male's abdomen with the dimensional change measured during resting breathing. The abdominal signal was differentiated ($F_{m}$) and compared with the accurate standard air flow rate signal ($F_{s}$) obtained by pneumotachometry. $F_{m}$ and $F_{s}$ differed in waveform, but the start and end timings of each breaths were clearly synchronized, demonstrating that the respiratory frequency could be accurately estimated before further processing of $F_{m}$. $F_{m}-F_{s}$ loop showed a nonlinear hysteresis within each breath period, thus 6 piecewise linear approximation was performed, leading to a mean relative error of 14 %. This error level was relatively large for clinical application, though customized calibration seemed feasible for monitoring general variation of ventilation. The present technique would be of convenient and practical application as a new wearable respiratory transducer.

• 한국가시화정보학회:학술대회논문집
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• 2005.12a
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• pp.17-22
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• 2005

An experimental study was carried out to investigate the effect of local ultrasonic forcing on a turbulent boundary layer. Stereoscopic particle image velocimetry (SPIV) was used to probe the characteristics of the flow. A ultrasonic forcing system was made by adhering six ultrasonic transducers to the local flat plate. Cavitation which generates uncountable minute air-bubbles having fast wall normal velocity occurs when ultrasonic was projected into water. The SPIV results showed that the wall normal mean velocity is increased in a boundary layer dramatically and the streamwise mean velocity is reduced. The skin friction coefficient ($C_{f}$) decreases $60\%$ and gradually recovers at the downstream. The ultrasonic forcing reduces wall-region streamwise turbulent intensity, however, streamwise turbulent intensity is increased away from the wall. Wall-normal turbulent intensity is almost the same near the wall but it increases away from the wall, In tile vicinity of the wall, Reynold shear stress, sweep strength and production of turbulent kinetic energy were decreased. This suggests that the streamwise vortical structures are lifted by ultrasonic forcing and then skin friction is reduced.

• Bulletin of the Korean Chemical Society
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• v.25 no.8
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• pp.1165-1170
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• 2004

The applicability of the combined nearly ideal binary solvent/Redlich-Kister (CNIBS/R-K) equation for correlation of various solvatochromic parameters (SP) with composition is shown employing 84 experimental data sets for aqueous and organic binary solvent systems at temperatures ranging 15 to $75^{\circ}C$. The model provides a simple computational model to correlate/predict different SP values in various binary solvent systems. In proposed equations, $MPD_s$ (mean percentage deviations) are between 0.0500% and 6.9591% in mixtures of dimethyl sulfoxide with 2-methylpropan-2-ol and benzene with 2-methylpropan-2-ol, respectively. Correlation of the calculated and experimental values of various SP give an equation with an overall mean percentage deviation (OMPD) of 1.1900, $R^2$ = 0.99692, s.e = 0.01223 and F = 341925.51. Approximately 70% of the calculated SP values have IPD (individual percentage deviation) lower than one and it is possible to predict unmeasured SP values by using only eight experimental data.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.6
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• pp.727-735
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• 1996

The effects of four factors-two dietary protein levels (12 and 16%), feeding methods(ad libitum and restricted), strains (A and B), and age of hens-on egg quality and laying performance were examined. Use of the 12% dietary protein level resulted in significantly lower (p < 0.05) hen-day egg production, higher feed intake to about 85% of the ad libitum intake decreased mean hen-day production. Significant feeding method-by-age interactions ($F{\times}A$) were obtained for all parameters. Restricted feeding had favorable effects on shell strength and Haugh unit values after 28 and 16 weeks of egg production, respectively. There was significant difference in shell strength between the two strain. Examination of the three-factor interaction among protein levels, feeding method and strain ($P{\times}F{\times}S$) disclosed that the favorable effect of the A strain on shell strength was significant only with the 16% protein-restricted fed group. The other treatment group did show a trend for greater shell strength of the A strain. Mean values for all the parameters examined changed significantly (p < 0.01) with the age of hens. Feed intake per dozen eggs tended to increase, with some fluctuation, as the hens aged. There was a linear decrease in Haugh unit scores and shell strength. The effect of restricted feeding on either shell strength or Haugh unit scores were favorable for the aged chickens.

• The Korean Journal of Applied Statistics
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• v.34 no.5
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• pp.711-721
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• 2021

In this paper, we propose the method of adjusting thresholds using impurity indices in classification analysis on imbalanced data. Suppose the minority category is Positive and the majority category is Negative for the imbalanced binomial data. When categories are determined based on the commonly used 0.5 basis, the specificity tends to be high in unbalanced data while the sensitivity is relatively low. Increasing sensitivity is important when proper classification of objects in minority categories is relatively important. We explore how to increase sensitivity through adjusting thresholds. Existing studies have adjusted thresholds based on measures such as G-Mean and F1-score, but in this paper, we propose a method to select optimal thresholds using the chi-square statistic of CHAID, the Gini index of CART, and the entropy of C4.5. We also introduce how to get a possible unique value when multiple optimal thresholds are obtained. Empirical analysis shows what improvements have been made compared to the results based on 0.5 through classification performance metrics.

• Journal of Korean Academy of Nursing
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• v.29 no.3
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• pp.625-638
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• 1999

The purpose of this study was to identify the relationships among health promoting behaviors, Health Locus of Control(HLOC), and response patterns to HLOC in Korean elderly. The sample was composed of 162 healthy elderly ranging in age from sixties to eighties. The instruments for this study were modified Health Promoting Lifestyle Profile (45 items, 4 scales), and Multidimensional Health Locus of Control (18 items). For the in data analysis, SPSS PC$^{＋}$ program was uilized for descriptive statistics, Pearson correlation, t-test, ANOVA and Stepwise multiple regression. The results of the study are as follows : 1. The total mean score for the HPLP was 2.411 (range 1-4), and the mean scores on the subscales were 3.324 for nutition, 2.709 for interpersonal support, 2.495 for exercise,2.225 for health responsibility, 2.205 for self actualization, 2.026 for stress management. 2. The mean scores for the HLOC in the elderly were HLOC-I : 23.531, HLOC-P : 21.914, HLOC-C : 18.667. 3. The response patterns of the HLOC identified eight types, pure internal, pure powerful others, pure chance, double external, believers in control, yea sayer, nay sayer and complex control. The “believers in control” was the largest group (22.8%), and “yea sayer” was the next largest group(17.9%). The “nay sayer”(5%) was the smallest group. 4. Demographic variables, such as education, economic status, religion and the perception of the health status showed strong connections to health promoting behaviors. 5. The HLOC-I and health promoting behavior were correlated positively(r＝.165, P＝.017), but the HLOC-P, the HLOC-C and the health promoting behavior were not correlated at the level of statistical significance. 6. There was not significant difference in health promoting behavior depending on the response patterns of the HLOC(F=1.171, P=.108). But, there were significant differences in two subscales of health promoting behavior exercise (F=3.279, P=.002), and stress management (F=3.165, P＝.003). 7. Education, the perception of the health and economic status explained 21.0% of the variance for health promoting behaviors. These results suggest that several demographic factors are important factors in predicting the level of health promoting behaviors in elderly. So to enhance the health promoting behavior, nurses should use the different nursing strategies depending on the demographic characters of the elderly.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.3
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• pp.240-246
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• 2006

This paper performed to investigate on vertical temperature distribution, effective draft temperature (ETD) and PMV (Predicted Mean Vote) in the classroom, which is located YangSan city (Kyungsangnam-Do), Korea, is equipped with ceiling unit. The vertical temperature difference between F.L+10 cm (ankle) and F.L+120 cm (neck) of a measuring point which is adjacent corridor in the classroom showed about $1^{\circ}C$ but of measuring point which is adjacent outdoor expressed up to $4^{\circ}C$, The effective draft temperature (ETD) is -2.3 and -0.52 and 0.67 at near ceiling unit but is 1.2 and 3.3 at far from ceiling unit. The PMV of total classroom showed the range of 'Cold' and 'Slightly Cold.' Therefore, to achieve comfort condition in the classroom is equipped with ceiling unit, the location of ceiling unit and discharge angle and discharge distance from ceiling unit are very important elements.