• Survey Research
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• v.4 no.1
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• pp.1-29
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• 2003

Telephone surveys miss, among other people, those who live in homes without telephones, people who are away from home at the time of interview and people who refuse to be interviewed. Recently, mobile phone survey has emerged as “A replacement technology” to the old telephone survey method. Mobile survey enables us to do many things we could not do or could not afford to do before, and reatly enhance the efficiency if the opinion surveys. Very specifically, the mobile survey enables us to control respondent's accessability, interviewer bias and to do incredibly fast and at a affordable costs. The authors analyze the results of mobile-phone local election polls and ELSI bio-technology attitude survey. The authors describe their results, the methods they used, including the use of demographic and propensity weighting to correct for substantial biases in the raw, unweighted data. The results show that mobile survey can predict the election outcomes with approximately equal accuracy to that of the telephone poll after weighting. This paper also cautions readers not to assume that mobile survey can be used with equal success in other elections and emphasizes the need for continuing research to improve mobile survey methods in the future.

• Journal of Microbiology and Biotechnology
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• v.17 no.4
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• pp.644-649
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• 2007

Response surface model was developed for predicting the growth rates of Salmonella enterica sv. Typhimurium in tryptic soy broth (TSB) medium as a function of combined effects of temperature, pH, and NaCl. The TSB containing six different concentrations of NaCl (0, 2, 4, 6, 8, and 10%) was adjusted to an initial of six different pH levels (pH 4, 5, 6, 7, 8, 9, and 10) and incubated at 10 or $20^{\circ}C$. In all experimental variables, the primary growth curves were well $(r^2=0.900\;to\;0.996)$ fitted to a Gompertz equation to obtain growth rates. The secondary response surface model for natural logarithm transformations of growth rates as a function of combined effects of temperature, pH, and NaCl was obtained by SAS's general linear analysis. The predicted growth rates of the S. Typhimurium were generally decreased by basic (9, 10) or acidic (5, 6) pH levels or increase of NaCl concentrations (0-8%). Response surface model was identified as an appropriate secondary model for growth rates on the basis of coefficient determination $(r^2=0.960)$, mean square error (MSE=0.022), bias factor $(B_f=1.023)$, and accuracy factor $(A_f=1.164)$. Therefore, the developed secondary model proved reliable predictions of the combined effect of temperature, NaCl, and pH on growth rates for S. Typhimurium in TSB medium.

• Journal of Labour Economics
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• v.43 no.1
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• pp.59-91
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• 2020

The recent reform of child care policy is to give priority to double-income households in the use of childcare facilities. This study analyzed the effect of the use of childcare facilities on the employment of married women under the on-going reform. Using the data from the 19th and 21st wave of the Korean Labor and Income Study, the marginal treatment effect (MTE) analysis method was used to eliminate the selection bias in which the sub-population targeted for policy is determined according to the priority when childcare demand exceeds supply. The study finds that the employment effect of married women who use childcare facilities does not differ statistically from the employment effect of married women who do not use childcare facilities.

• The Journal of Korean Physical Therapy
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• v.22 no.2
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• pp.69-75
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• 2010

Purpose: The purpose of this study was to investigate the relationship between subjective quality of life and job stress with regard to general characteristics and health characteristics of physical therapists (PTs) and occupational therapists (OTs). Methods: The study involved administering questionnaires to 93 PTs and OTs who worked in urban medical institutions between November 2009 and October 2009. A questionnaire (KvSBQOL) developed by Dunbar and colleagues and translated into Korean version by Yoon et al was used for measuring subjective quality of life. A questionnaire developed by Kim was used for measuring job stress. Results: Among PTs and OTs, the mean quality of life score was 3.10 points and the mean level of job stress was 3.42. Female PTs and OTs had significantly greater levels of job stress. Those PTs and OTs in the 'Lowest pay' group and in the 'Associated Degree' group reported the lowest quality of life. Those in the 'Very healthy' group of PTs and OTs had significantly lower job stress than the other groups. The group with the highest job stress had the lowest quality of life. A limitation of this study was that all data was self-reported and subject to associated bias. Conclusion: To prevent loss of business services by PTs and OTs, it is important to know how job stress affects quality of life. Our findings suggest that a reduction in job stress can improve quality of life among PTs and OTs.

• Journal of Preventive Medicine and Public Health
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• v.33 no.1
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• pp.125-133
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• 2000

Objectives : This study uses meta-analysis methodology to examine the statistical consistency and importance of random variation among results of epidemiologic studies of occupational electromagnetic field exposure and leukemia. Methods : Studies for this meta-analysis were identified from previous reviews and by asking researcher active in this field for recommendations. Overall, 27 studies of occupational electromagnetic field exposures and leukemia were reviewed. A variety of meta-analysis statistical methods have been used to assess combined effects, to identify heterogeneity, and to provide a single summary risk estimate based on a set of simiar epidemiologic studies. In this study, classification of exposure metircs on occupational epidemiologic studies are reported for (1) job classification (20 individual studies); (2) leukemia subtypes (13 individual studies); and (3) country (27 individual studies). Results : Results of this study, an inverse-variance weighted pooling of all the data leads to a small but significant elevation in risk of f 1% (OR=1.11, 95% CI : $1.06\sim1.16$) among 27 occupational epidemiologic studies. Publication bias was assessed by the 'fail-safe n' that may be not influence for all combined results exception a few categories, ie, 'power station operators' and 'electric utility workers' by job classification on occupational study. And ail combined odds ratio results were similar for fixed-effects models and random-effects models, with slightly higher risk estimates for the random-effects model in situations where there was significant heterogeneity, ie, Q-statistic significant (p<.05). Conclusions : We found a small elevation in risk of leukemia, but the ubiquitous nature of exposure to electromagnetic fields from workplace makes even a weak association a public health issue of substantial power to influence the present overall conclusion about relationship between electromagnetic fields exposure and leukemia.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10C
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• pp.921-926
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• 2006

The Presence of a line-of-sight(LoS) blockage can degrade the UWB positioning accuracy for two reasons. Firstly, it makes estimation of the time of arrival(ToA) of the direct path signal difficult by complicating the multipath structure of the propagation channel. Secondly, the higher dielectric constant of the LoS blocking material than that of free space introduces excess propagation delay which will bias the range estimation. In this paper, methods based on ray tracing to reduce the ranging error resulting from the second reason are Posed. We take two different approaches; a statistical approach and a map-aided method. In the statistical approach, we establish a conditional distribution of the excess propagation delay caused by LoS blockages using a ray tracing technique. The lo6wer bound of the ranging performance based on this model is estimated. Ine ray tracing method is also used for the map-aided ToA positioning approach. UWB propagation measurement data taken in an office environment is used to examine the performance of this method.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.1
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• pp.33-44
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• 2003

This study was conducted to estimate the design flood by the determination of best fitting order for LH-moments of the annual maximum series at fifteen watersheds. Using the LH-moment ratios and Kolmogorov-Smirnov test, the optimal regional probability distribution was identified to be the Generalized Extreme Value (GEV) in the first report of this project. Parameters of GEV distribution and flood flows of return period n years were derived by the methods of L, L1, L2, L3 and L4-moments. Frequency analysis of flood flow data generated by Monte Carlo simulation was performed by the methods of L, L1, L2, L3 and L4-moments using GEV distribution. Relative Root Mean Square Error. (RRMSE), Relative Bias (RBIAS) and Relative Efficiency (RE.) using methods of L, Ll , L2, L3 and L4-moments for GEV distribution were computed and compared with those resulting from Monte Carlo simulation. At almost all of the watersheds, the more the order of LH-moments and the return periods increased, the more RE became, while the less RRMSE and RBIAS became. The Absolute Relative Reduction (ARR) for the design flood was computed. The more the order of LH-moments increased, the less ARR of all applied watershed became It was confirmed that confidence efficiency of estimated design flood was increased as the order of LH-moments increased. Consequently, design floods for the appled watersheds were derived by the methods of L3 and L4-moments among LH-moments in view of high confidence efficiency.

• Journal of Oriental Neuropsychiatry
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• v.31 no.3
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• pp.169-186
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• 2020

Objectives: The purpose of this study was to provide clinical evidence to support the use of acupuncture combined herbal medicine for post-stroke depression. Methods: Studies were identified by searching Pubmed, EMBASE, Cochrane Library, NDSL, RISS, KMbase, KISS, and CNKI. Randomized controlled trials that verified effects of the acupuncture combined with the herbal medicine for PSD were included in this study. Literature searches of English, Chinese, and Korean databases were performed. Two authors independently extracted the data and assembled the study quality. Results: Of 698 RCTs screened, 17 RCTs were selected. Most of the studies had unclear risk of bias. Among the 17 RCTs, 10 were meta-analyzed. As for the outcome measurement, the effective rate and the HAMD were most commonly used. The meta-analysis of the studies revealed that the PSD cure effective rate in the acupuncture combined with herbal medicine group was higher than that in the Western medicine group (RR: 1.23, 95% CI: 1.14 to 1.33, p<0.00001, I²=0%). Also, the HAMD in the acupuncture combined with herbal medicine group was significantly different compared to the Western medicine group (MD -5.54, 95% CI -9.80 to -1.29, p=0.01, I²=99%). The quality of the selected RCTs was low. Conclusions: Acupuncture combined with herbal medicine is effective for treating post-stroke depression. However, It is worth noting that the included studies were of relatively poor quality. The sample sizes were also small. Based on the findings of this study, further investigations into the diagnosis and treatment of PSD are warranted.

• Journal of the Korean Society for Nondestructive Testing
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• v.5 no.1
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• pp.34-47
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• 1985

The developing country, KOREA where does not possess the natural resources for traditional energy such as oil and gas, so. The nuclear energy is the most single reliable source available for closing the energy gap. For these reason, It is inavoidable to construct the nuclear power plant and to develop technology related nuclear energy. The rate of operation in large nuclear power facilities depends upon the performance of work system through design and construction, and also the applied technology. Especially, it is the most important element that safety and reliability in operation of nuclear power plant. In view of this aspects, Nuclear power plant is performed severe examinations during preservice and inservice inspection. This study provide an automation of analysis for volumetric examination which is required to nuclear power plant components. It is composed as follows: I. Introduction II. Inservice Inspection of Nuclear Power Plant ${\ast}$ General Requirement. ${\ast}$ Principle and Methods of Ultrasonic Test. ${\ast}$ Study of Flaw Evaluation and Design of Classifying Formula for Flaws. III. Design of Automation for Flaw Evaluation. IV. An Example V. Conclusion In this theory, It is classifying the flaws, the formula of classifying flaws and the design of automation that is the main important point. As motioned the above, Owing to such as automatic design, more time could be allocated to practical test than that of evaluation of defects, Protecting against subjective bias tester by himself and miscalculation by dint of various process of computation. For the more, adopting this method would be used to more retaining for many test data and comparative evaluating during successive inspection intervals. Inspite of limitation for testing method and required application to test components, it provide useful application to flow evaluation for volumetric examination. Owing to the characteristics of nuclear power plant that is highly skill intensive industry and has huze system, the more notice should be concentrated as follows. Establishing rational operation plan, developing various technology, and making the newly designed system for undeveloped sector.

• Journal of Korea Water Resources Association
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• v.43 no.11
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• pp.977-984
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• 2010

In order to determine the optimal sediment discharge formula for Hyeongsan river, some statistical approaches have been applied to analyze the simulated results of long-term bed change by HEC-6. The field measurements have been conducted to obtain the data for model calibration and verification such as sediment discharge, bed material, and channel geometry. Several sediment discharge formulae have been verified according to the bias, RMSE, RRMSE, discrepancy ratio, and S/N ratio of bed change along the thalweg. Comparing the formulae, Laursen formula(modified by Copeland) have shown the best performance to simulate the long-term bed change of Hyeongsan river.