• ETRI Journal
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• v.31 no.6
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• pp.667-674
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• 2009

Terahertz time-domain spectroscopy has been used to study the optical and dielectric properties of three chalcogenide glasses: $Ge_{30}As_8Ga_2Se_{60}$, $Ge_{35}Ga_5Se_{60}$, and $Ge_{10}As_{20}S_{70}$. The absorption coefficients ${\alpha}({\nu})$, complex refractive index n(${\nu}$), and complex dielectric constants ${\varepsilon}({\nu})$ were measured in a frequency range from 0.3 THz to 1.5 THz. The measured real refractive indices were fitted using a Sellmeier equation. The results show that the Sellmeier equation fits well with the data throughout the frequency range and imply that the phonon modes of glasses vary with the glass compositions. The theory of far-infrared absorption in amorphous materials is used to analyze the results and to understand the differences in THz absorption among the sample glasses.

• Journal of The Korean Association For Science Education
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• v.18 no.4
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• pp.617-626
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• 1998

Inquiry approach in teaching science has been widespread in Korea since the Third National Curriculum in 1970's. But the effect of the approach has never been evaluated systematically in Korea, so the science educators do not know if the inquiry approach really works and if any critical problems inhibit the effect of the approach. In this context, the NAEP of the Unied States and the APU of the United Kingdom were model programs for assessing the effect of the inquiry approach in teaching science. The purpose of this study is to develop an assessment system for evaluating the effect of inquiry teaching in elementary and secandary schools. For this purpose, an assessment framework and 240 test items were developed and tried with a sample of 8,906 students. The results say that the developed tests are reliable. The average Cronbach $\alpha$ reliability coefficient of the tests was 0.69. The discrimination index(point-biserial correlation coefficient) ranged from 0.39 to 0.54 with a mean of 0.49, which indiate they are excellent in discriminating students in terms of their inquiry achievement. The test items were also analyzed by "item response theory." The results also say that the items are successfully developed.

• Korea Journal of Hospital Management
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• v.7 no.1
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• pp.1-18
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• 2002

Empowerment is a multifaceted concept which can be described somewhat differently. In general, it is defined as the motivational concept of autonomy and self-efficacy. Recently, this concept of empowerment is applied to improve organizational staff's job satisfaction and organizational commitment in many organizations. Empowerment in service organizations has certainly generated more publicity than any other organizations. The objective of this study is to measure the degree of hospital administrative staff's empowerment using Spreitzer(1995)'s empowerment theory, and also to analyze the relationship of empowerment and job satisfaction and organizational commitment. Spreitzer argues that the work empowerment is composed of 4 dimensions (meaning, competence, self-determination, and impact) and each dimension influences employee's job satisfaction, organizational commitment, and organizational performance in the end. In order to carry out this study, data were collected by self-administered Questionnaires from 181 hospital administrative staff at 3 university hospitals in Inchon and Kyunggi-Do. The response rate is 86%. The Collected data were analyzed with SPSS statistical package V10.0. The major findings of this study are as follows: First, the degree of hospital administrative staff's empowerment is a high level point at the 7 Likert Scale. Second, the reliability of 3 variables, empowerment, job satisfaction and organizational commitment, was statistically satisfied(Cronbach's alpha>0.80). Third, as a result of correlation analysis, four components of empowerment, job satisfaction and organizational commitment showed a positive relationship. Finally, multiple regression analysis was conducted to find the impact of empowerment on job satisfaction and organizational commitment. In the case of job satisfaction, the meaning and competence factors have a positive effect(P<0.05). And the case of organizational commitment, the meaning and impact components have a positive relation(p<0.05). These results showed that the workplace empowerment is significantly related to employee's job satisfaction and organizational commitment.

• Journal of the Korean Society of Costume
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• v.43
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• pp.187-202
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• 1999

The objectives of this study were to analyze the effect of dress(Korean traditional dress and suit) of elderly Women and situation on impression formation. The experimental design was $10\times{2}\times{2(dress}\times{perceiver's age}\times{situation)}$ factorial design by 3 independent variables. The stimuli of color photographs of female in her 60's model and the semantic differential scale were used. Six variables of impression formation were used: preference: elegance: potency: activity: feminine: and modernity. Samples were 400 women 200 were in their twenties and 200 in their forties and fifties. The data were analyzed by $\alpha$-reliability t-test ANOVA and duncan's multiple range test. The Korean traditional dress with the combination of Korean traditional color(light blue upper dress with dark red purple collar and string.dark blue skit) had the most positive effect on impression of elegance. Pink traditional dress and light blue traditional dress had a negative effect on impression of potency activity and modernity. Red purple suit had a positive effect on potency and modernity. The interaction between dress perceiver's age and stituation was significant for the impression of activity. Women in their 40's and 50's perceived the activity of red purple suit positively in the situation of alumnae meeting more than in the wedding ceremony. The perceived age of the stimulus person was different according to dresses. Traditional dresses was perceived older than suits were. Women in their 40's and 50's evaluated preferences of the dresses positively more than 20's did. This means that 40's and 50's feel similarity with the stimulus person more than 20's as the age of model was in their 60's The result supports the theory that similarity is basic factor in interpersonal attraction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.2
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• pp.59-68
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• 1987

Several series of fracture tests were conducted to explore the fracture characteristics and to determine the fracture energy of concrete. A stable three-point bend test was employed to generate the load-deflection curves. The fracture energy may then be calculated from the area under the complete load-deflection curve. The initial notch-to-beam depth ratio (${\alpha}_0$/H) was varied from zero to 0.6. The prediction formula for the fracture energy of concrete is also derived and is found to depend on the tensile strength and aggregate size. The proposed fracture energy formula can be used for the fracture analysis of concrete structures. The present study also devises an equivalent crack length concept to predict the maximum failure loads of concrete beams. A simple formula for the equivalent crack length is proposed.

• Journal of the Korean Chemical Society
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• v.40 no.6
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• pp.420-426
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• 1996

The critical micelle concentration(CMC) and the counterion binding $constant(\beta)$ at the CMC of the mixtures of Sodium dodecylsulfate(SDS) with Sodium dodecylbenzenesulfonate(DBS) in aqueous solutions have been determined from the concentration dependence of electrical conductance at several temperatures from $15^{\circ}C$ to $35^{\circ}C.$ Thermodynamic parameters(${\Delta}C_p,\;{\Delta}G_m^{\circ},\;{\Delta}H_m^{\circ}$ 및 ${\Delta}S_m^{\circ}$ and ${\Delta}C_p$), associated with the micelle formation of SDS/DBS mixtures, have been estimated from the temperature dependence of CMC and $\beta$ values. The measured values of ${\Delta}G_m^{\circ}\;and\;{\Delta}C_p$ are negative but the values of ${\Delta}S_m/^{\circ}$ are positive in the whole measured temperature region. The significance of these thermodynamic parameters and their relation to the theory of the micelle formation of SDS/DBS mixtures have been also considered.

• Bulletin of the Korean Chemical Society
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• v.25 no.9
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• pp.1314-1320
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• 2004

The adsorption and configuration of CO molecules adsorbed on W (110) and W (100) surfaces have been calculated by the atomic superposition and electron delocalization molecular orbital (ASED-MO) method. Referred to as the ASED-MO method, it has been used in the present study to calculate the geometries, binding energies, vibrational frequencies, orbital energies, reduced overlap population (ROP), and charges. From these results adsorption properties of ${\alpha}$-state and ${\beta}$-state were deduced. The calculated binding energies are in good agreement with the experimental result. On the W (110), the calculated average binding energies are 2.56 eV for the end-on configuration and 3.20 eV for the lying-down configuration. Calculated vibrational frequency is 1927 $cm^{-1}$ at a 1-fold site and 1161 $cm^{-1}$ at a long-bridge (2) site. These results are in reasonable agreement with experimental values. On the W(100) surface, calculated average binding energies of the end-on and the lying-down are 2.54 eV and 4.02 eV respectively. The differences for binding energy and configuration on the surfaces are explained on the basis of surface-atom coordination and atom-atom spacing. In the favored lyingdown CO configuration on the W(110) and W(100) surfaces, 4 ${\sigma}$ and 1 ${\pi}$ donation interactions, coupled with the familiar 5 ${\sigma}$ donation to the surfaces and back-donations to the CO 2 ${\pi}^{\ast}$ orbital, are responsible for adsorption to the surface.

• Journal of the Korean Society for Precision Engineering
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• v.4 no.3
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• pp.44-51
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• 1987

In metal cutting various types of chips are produced in consequence of cutting conditions. Flow-type chips have been studied in most cases because they are easier to be analyzed, but the actual surfaces of chips are not smooth, but crushed. This paper deals with saw-toothed chips, special types of flow-type chips, which have deep concaves and high convexes and sharp angles on the free surface. I tried to establish the theory of saw-toothed chip mechanism through experimental observation, that is, the mathmatical model of the cutting energy and cutting mechanism through the geometrical observation of the chips by using a microscope. The results obtained are as follows: 1. The mechanism of saw-toothed chips is diffenent from that of general flow-chips. 2. In the case of saw-toothed chips, the shear angle must be measured by the hypotenuse angle and the rake angle, and the shear angle is more affected by the rake angle than by the hypotenbuse angle. 3. The friction angle is represented by .beta. = . pi. /4+ .alpha./ sub n/- .phi. which is different from Merchant's equation. 4. The pitch and the slip are greatly influenced by depth of cut, but the influence of the rake angle on it is small. 5. The normal stress and the shear stress on the shear plane decrease with the increase of the cutting depth, and they are almost independent on the variation of a rake angle. 6. The unit friction energy on the tool face, the unit shear energy on the shear plane, and the total cutting energy per unit volume decrease with the increase of rake angle and cutting depth.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.6
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• pp.2947-2951
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• 2016

A quasi-experimental study was conducted to develop a health education modification program based on self-efficacy and motivation regarding liver flukes and cholangiocarcinoma development in Keang Sanam Nang district, Nakhon Ratchasima province, Thailand. A total of 36 individuals were invited to participate in the program and were screened for population at risk of liver fluke infection and cholangiocarcinoma using SUT-OV-001 and SUT-CCA-001. Development of health education modification program regarding liver fluke and cholangiocarcinoma prevention included 3 steps: (1) preparation, (2) health education program, and (3) follow-up and evaluation. The study was implemented for 10 weeks. Pre-and-post-test knowledge was measured with questionnaires, Kuder-Richardson-20: KR-20 = 0.718,and Cronbach's Alpha Coefficient = 0.724 and 0.716 for percection and outcome expectation questionnaires. Paired and independent t-tests were applied for data analysis. The majority of the participants were female (55.6%), aged between ${\leq}50$ and 60 years old (36.1%), married (86.1%), education level of primary school (63.9%), agricultural occupation (80.6%), and income <4,000 Baht (44.4%). The results revealed that after the health education program, the experimental group had a mean score of knowledge, perception, and outcome expectation regarding liver fluke and cholangiocarcinoma prevention significantly higher than before participation and in the control group. In conclusion, this successful health education modification program for liver fluke and cholangiocarcinoma, therefore may useful for further work behavior modification in other epidemic areas.

• Geomechanics and Engineering
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• v.14 no.2
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• pp.107-113
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• 2018

Coal samples with different joints morphology were subjected to uniaxial compression experiments, cracks evolution was recorded by Nikon D5300 and acoustic emission (AE) energy signals were collected by AEwin Test for Express-8.0. During loading process, coal samples deformed elastically with no obvious cracks changes, then they expanded gradually along the trace of the original cracks, accompanied by the formation of secondary cracks, and eventually produced a large-scale fracture. It was more interesting that the failure mode of samples were all shear shape, whatever the original cracks morphology was. With cracks and damage evolution, AE energy radiated regularly. At the early loading stage, micro damage and small scale fracture events only induced a few AE events with less energy, while large scale fracture leaded to a number of AE events with more energy at the later stage. Based on the multifractal theory, the multifractal spectrum could explain AE energy signals frequency responses and the causes of AE events with load. Multifractal spectrum width (${\Delta}{\alpha}$), could reflect the differences between the large and small AE energy signals. And another parameter (${\Delta}f$) could reflect the relationship between the frequency of the least and greatest signals in the AE energy time series. This research is helpful for us to understand cracks evolution and AE energy signals causes.