• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.1148-1151
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• 2002

Dielectric ceramics with nominal composition of $(Ba_{0.93}Sr_{0.07}O)-0.5Sm_2O_3-4.5TiO_2$ was prepared using the conventional mixed oxide process-derived powder. Effect of $SiO_2$, $MnO_2$ and $Al_2O_3$ impurity addition on the microwave properties was examined in some detail. Measured relative permittivity $(\varepsilon_r)$ values were in the range of 53 to 59 and showed little dependence on impurity addition. In contrast, quality factor $(Q{\cdot}f)$ and temperature coefficient of resonant frequency $(\tau_f)$ values were greatly influenced by the type and the amount of impurities. It was found that 0.1~0.2wt% addition of $Al_2O_3$ was most effective for improving the properties, where ${\varepsilon}_r$, $Q{\cdot}f$ and $\tau_f$ values were 57.7, 10000, and +7ppm/$^{\circ}C$, respectively.

• Food Science of Animal Resources
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• v.41 no.5
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• pp.779-787
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• 2021

This study compared the meat quality characteristics, palatability, and histochemical characteristics of low-marbled Hanwoo and Holstein steers of different beef quality grades (1, 2, and 3). No differences were observed in muscle pH_{24 h} and cooking loss between the groups (p>0.05); however, quality grade 1 of Hanwoo steers (HA1) showed a darker muscle surface compared to grade 1 of Holstein steers (HO1) (30.9 vs. 33.9, p<0.05). The HA2 group exhibited a lower value of Warner-Bratzler shear force compared to the HO1 and HO3 groups (60.8 vs. 69.2 and 87.8 N, p<0.001). For sensory quality attributes, steaks from the HA1 group showed higher scores of softness, initial tenderness, and amount of perceptible residue than steaks from the HO1 group (p<0.001). Within the quality grade 2, Hanwoo steers had a higher score of softness compared to Holstein steers (p<0.001). There were no differences in juiciness and flavor intensity between Hanwoo and Holstein steers at the same quality grade (p>0.05). This difference in tenderness attributes between the breeds within the quality grade was associated with morphological traits of muscle bundle, and Hanwoo steers had smaller bundle area (0.37 vs. 0.50 mm², p<0.05) and higher fiber number per bundle (88.2 vs. 121, p<0.05) compared to Holstein steers. Therefore, bundle characteristics of longissimus thoracis muscle can be crucial for explaining factor for the explanation of tenderness variations between different breeds at the same beef quality grade or marbling.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.1
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• pp.74-79
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• 2002

The EM(Engineering Model) VCO(Voltage Controlled Oscillator) is nonlinear designed for LO(Local Oscillator) of Ka-band satellite transponder. The microstripline coupled with dielectric resonator is implemented as a high impedance inverter to improve the phase noise, and the quality factor of resonant circuit can be transferred to active device with the enhanced loaded quality factor. The developed VCO has the oscillating tuning range of 9.7965~9.8032 GHz for the control voltage range of 0~12 V. This VCO requires the DC power of 8 V and 17 mA. The phase noise characteristics are -96.51 dBc/Hz @10 KHz and -116.5 dBc/Hz @100 KHz, respectively. And, the output power of 7.33 dBm is measured.

• The Korean Journal of Food And Nutrition
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• v.27 no.3
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• pp.427-434
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• 2014

This study investigated the quality characteristics of cookies containing mugwort powder, which is well known for its various functions and biological activity. Cookie samples were made by adding the mugwort powder at different levels of 0%, 1%, 3% and 5%. In this study, moisture, pH, color, spread factor, hardness, antioxidant activity and sensory evaluation of cookies were examined. The pH and moisture were increased when increasing levels of mugwort powder were used. The L, a and b color values were significantly (p<0.001) decreased when increasing levels of mugwort powder were used. The spread factor of the cookies was significantly (p<0.01) decreased when increasing levels of mugwort powder were used.. The hardness and DPPH radical scavenging activity of cookies were significantly (p<0.001) increased when increasing levels of mugwort powder were used. Cookies containing 3% of mugwort powder showed the highest taste and texture scores. The scores for Flavor and color decreased when more mugwort powder was added.

• Journal of Korean Society for Quality Management
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• v.44 no.1
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• pp.199-214
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• 2016

Purpose: The present study was designed to examine the casual relationships among performance and arts information service quality, initial trust, user satisfaction, reuse intention and prosumer activity in social network service(SNS). Also, we intended to explore significant factors on use performance of SNS through causal model analysis in the viewpoint of total effect. Methods: As a survey tool, questionnaire has obtained validity and reliability through literature survey, exploratory survey and pretest and sample 403 was selected. For statistical treatment of pretest and main analysis, SPSS18.0 and AMOS18.0 were employed and structural equation model was employed as analysis method. Results: Result of this study shows as follows. Two factors (precision and reciprocal action) have an effect on user satisfaction, initial trust, reuse intention and prosumer activity. We found that with an importance of initial trust, prosumer activity can be a useful and significant factor in causal relationship of SNS. Conclusion: The present study shows that two factors(precision and reciprocal action) in via of initial trust, were important factors that related companies have to emphasize to raise performance, And also we confirmed new factor 'prosumer activity' through this study. However, the present study has some limitations to be studied in the future.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.9
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• pp.794-797
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• 2002

Piezoelectric properties of PZT-PSN ceramics were investigated as a function of WO$_3$ addition from 0 wt% to 6.0 wt%. The dielectric and piezoelectric characteristics of PZT-PSN ceramics have been investigated at different calcination (80$0^{\circ}C$~90$0^{\circ}C$) and sintering (110$0^{\circ}C$~130$0^{\circ}C$) temperatures. The grain size was increased with the addition of WO$_3$and the sintering temperatures. Anisotropic properties of electromechanical coupling coefficient and piezoelectric coefficient are proven to be dependent on processing temperatures and amount of addition. At the specimen with 0.6 wt% WO$_3$ addition, using calcination temperature of 80$0^{\circ}C$ and sintering temperature of 110$0^{\circ}C$ , mechanical quality factor(Q$_{m}$) and electromechanical coupling coefficient(k$_{p}$) showed the excellent results of 1560 and 0.48, respectively Experimental results indicated that the PZT-PSN system ceramics with WO$_3$impurity could be effectively used for the microtransformer and actuator applications, etc.etc.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.282-285
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• 1999

The (1-x)MgTiO$_3$-xSrTiO$_3$(x=0,0.1) ceramics were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperature and composition ratio by XRD, SEM and DT-TGA. Increasing the sintering temperature from 130$0^{\circ}C$ to 1$600^{\circ}C$, second phase was decreased and grain size was increased. In the case of 0.9 MgTiO$_3$-0.1SrTiO$_3$ ceramics sintered at 130$0^{\circ}C$, dielectric constant, quality factor and temperature coefficient of resonant frequency were 22.61, 10,928(at 1GHz), +50.26ppm/$^{\circ}C$ , respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.791-794
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• 1999

Exact estimation of cement content in a hardened concrete can provide useful data to evaluate the quality and strength of the concrete and might be used to inspect the quality of precast concrete secondary products. Observation obtained in this research included : (1) the volume of coarse aggregate in the hardened concrete measured by the area comparison method has a high accuracy ; (2) the cement content in the mortar and the X-ray intensity of Ca-K$\alpha$ have a correlation factor of 0.96 ; (3) the cement content in the ready mixed concrete was estimated with high accuracy such as correlation factor of 0.99 and standard deviation of 0.64.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.5
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• pp.789-794
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• 1994

In this study, the structural and microwave dilelectric properties of 0.15BaO-0.15SmS12TOSI3T-0.7TiOS12T ceramics with sintering and annealing conditions were investigated. In the specimen sintered at 1350 [$^{\circ}C$], dielectric constant and quality factor were good values of 80.19,2006 (fS10T=4.6851[GHz]). To improve the $\tau$S1fT of specimen which was manufactured by the optimumsintering condition (1350[$^{\circ}C$],2[Hr.]), annealed from 2[hr.] to 16[hr.] at the annealing temperature of 1200 [$^{\circ}C$]. Increasing the annealing time, dielectric constant was almost constant and quality factor was increased. In the specimen of 4[hr.] annealed, the temperature coefficient of resonant frequency was minimum value, and increased with increasing the annealing time.

• Korean Journal of Environmental Agriculture
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• v.28 no.1
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• pp.86-91
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• 2009

The main purpose of this study is to search the water factor which influences to occurrence of the total coliforms. Occurrences rate of the total coliforms and the E coli were 57.9% 10.5% in 2007 and 47.4%, 23.7% in 2008 respectively. According to the result which examines the correlation analysis and a regression analysis, most the water factor which is effect was $Na^+$(0.497, p<0.05) in appearance of the total coliforms and was $Cl^-$(0.622, p<0.01) in appearance of the E coli. The water factor that simultaneously influences to the total coliforms and the E. coli appearances was the $Cl^-$. The predictable regression formula for appearance rate of the total coliforms was expressed as 0.462 + 0.028 [$Na^+$] - 0.644 [$COD_{Mn}$] - 8.889 [$PO_4-P$](R = 0.930, $R^2$ = 0.866, adjusted $R^2$ = 0.839, p<0.05), and that of the E coli was described as -0.012 + 0.004 [$Cl^-$](R = 0.622, $R^2$ = 0.387, adjusted $R^2$ = 0.351, p<0.05).