• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.6 s.249
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• pp.728-733
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• 2006

The reduction of the Vehicle interior noise has been the main interest of NVH engineers. The driver's perception on the vehicle noise is affected largely by psychoacoustic characteristic of the noise as well as the SPL. In particular, the HVAC sound among the vehicle interior noise has been reflected sensitively in the side of psychology. In previous study, we have developed to verify identification of source for the vehicle HVAC system through multiple-dimensional spectral analysis. Also we carried out objective assessments on the vehicle HVAC noises and subjective assessments have been already performed with 30 subjects. In this study, the linear regression models were obtained for the subjective evaluation and the sound quality metrics. The regression procedure also allows you to produce diagnostic statistics to evaluate the regression estimates including appropriation and accuracy. Appropriation of regression model is necessary to $R^2$ value and F-value. And testing for regression model is necessary to independence, homoscedesticity and normality. Also we selected optimum layout of damping material using Taguchi method. As a result of application, sound quality is improved more quietly, powerfully, even though costly, and smoothly.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.9
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• pp.839-846
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• 2014

Recent trends in the miniaturization and weight reduction of portable electronic parts have driven the use of subminiature screws with a micrometer-scale pitch. As both screw length and pitch decrease in subminiature screws, the resulting clamping force becomes diminishes. In this work, Finite element (FE) analysis is performed to evaluate clamping force of a screw assembly, with a comparison with experimental result. To improve clamping force of subminiature screws, a new screw design is considered by modifying screw thread angle: the thread angle is varied as an asymmetric way unlike the conventional symmetric thread angle. FE analyses are then performed to compare the clamping characteristics of each subminiature screw with different thread angle. The effect of thread angles on the clamping force is then discussed in terms of structural safety for both positive and negative screws.

• Journal of the Ergonomics Society of Korea
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• v.29 no.1
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• pp.139-144
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• 2010

Grape weeding work requires Ergonomics improvement, because it performs motion likely to cause Musculoskeletal disorders (MSDs) repeatedly and continuously. The object of this study was to reject workload in Grape weeding works raised MSDs with the Moving Rail-chair and Electromotive Scissors. As objective method of analysis, we used heart rate, EMG, RULA, REBA. As subjective method of analysis, we used questionnaire that indicate lethargy area of body, pain of muscle and bone. As a result, working with Moving Rail-Chair and Electromotive Scissors is lower heart rate and EMG than typical working. Also for the subjective evaluation, reducing of neck and shoulder movement makes improve workload.

• Journal of the Korean Society of Physical Medicine
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• v.4 no.1
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• pp.31-41
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• 2009

Purpose : Purpose of this study was to determine correlation between Walter Reed Visual Analogue Scale (WRVAS) and Scoliosis Research Society-22(SRS-22) questionnaire for idiopathic scoliosis. Methods : For this study, to assess reliability, 224 middle school female students were applied the WRVAS & SRS-22 questionnaire. Pearson correlation analysis was used to know correlationship between WRVAS and SRS-22 questionnaire. Regression analysis was used to know causation between WRVAS and SRS-22 questionnaire. Results Positive correlation(.248) was found between WRVAS score and SRS-22 score. And SRS-22 was shown positive correlation compared with WRVAS as a result slope of .078 Conclusion : The WRVAS questionnaire is reliable positive correlation with SRS-22 questionnaire. It is valid and may be useful for clinical evaluation of idiopathic scoliosis patients.

• Korean journal of food and cookery science
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• v.20 no.4
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• pp.409-417
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• 2004

The purpose of this study was to investigate the quality characteristics of Kugija-Injeulmi by varying the ingredient ratio of Lycii fructus powder (4, 6 and 8%). According to sensory evaluation of Kugija-Injeulmi, as the ratio of Lycii fructus powder was increased, the bitterness, hardness and chewiness all increased. It was found that Kugija-Injeulmi made of glutinous rice was moistened and softened with the addition of more Lycii fructus powder, but it was rougher than Kugija-Injeulmi made of glutinous rice flour. As a result of textural analysis of Kugija-Injeulmi, the hardness, adhesiveness, gumminess and chewiness increased as the amount of Lycii fructus powder increased, whereas the cohesiveness decreased. Kugija-Injeulmi made of glutinous rice was moister than Kugija-Injeulmi made of glutinous rice flour. The overall-acceptability was negatively correlated with coarseness. The overall-acceptability of Kugija-Injeulmi made of glutinous rice was much higher than that made of glutinous rice flour. From the above results, the most advisable mixture ratio of Kugija-Injeulmi is as follows Kugija-Injeulmi add 282g (94%) glutinous rice flour, Lycii fructus powder 18g (6%) and salt 3g. The moisture content was 42.22%.

• Journal of Korean Dental Science
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• v.10 no.1
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• pp.22-28
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• 2017

Purpose: The purpose of this study was to evaluate the dental fear experienced among Korean adolescents and to identify the relevant factors. Materials and Methods: In order to compare the level of dental fear depending on the subjects' previous experience, descriptive statistical analysis was performed. Gender- and grade-dependent evaluation was performed according to the presence of their previous dental visit and dental fear. Subjective oral health status was also investigated. In order to determine the factors affecting dental fear, logistic regression analysis was performed. Result: Among the total of 333 subjects who had experienced dental fear, females were found to experience 1.766 times greater dental fear than males (P=0.007). The worse subjective perception of their oral health was associated with increase in the experience of dental fear by 1.245-fold (P=0.047). Conclusion: The dental fear was likely to be formed during the visit to the dentist's office or through previous experience of dental treatment. Therefore in order to reduce the fear associated with dental treatment in adolescents, establishemnt of a proper environment in the dental clinic and a patient management program are necessitated.

• Korean Journal of Rural Living Science
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• v.7 no.2
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• pp.139-152
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• 1996

The objectives of this study are : (1) to measure the level of economic stress perception in Korean farm households. (2) to identify the effects of related variables such as socio-demographic variables and economic stability. The data from 505 farm households' wives was analyzed using statistical methods such as frequency, correlation, oneway ANOVA, lease significant difference test, and stepwise multiple regression. The major findings are as follows : The mean value of economic stress perception on the 505 wives was 33.5 points out of a possible 100. Among 3 subsectors, income stress perception had highest score. Socio- demographic variables such as family size, type of farm household, financial manager, debt, credit . grant assistant, wife's age, and educational level of the wife had a significant difference on the economic stress perception of wives in the ANOVA analysis. So did the objective and subjective evaluation of economic stability. As a result of multiple regression analysis, economic stability, debt presence, and wife age were verified explaining 23% of the variance of economic stress perception. Therefore, it can be said that farm wives had relatively high economic stress perception in the case of low economic stability, getting into debt and low age.

• Journal of Korean Society of Rural Planning
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• v.20 no.4
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• pp.165-182
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• 2014

The purpose of this study was to develop survey tools for diagnosis of capacity levels in business promotion of rural residents when performing a rural development project of a regional unit. The cases of previous studies were analyzed to select community capacity indicators related to a rural development project. Five indicators were derived : social capital, consciousness of participation, community spirit, and leadership. Based on the five indicators, measurement items of various capacities were selected and 54 survey items were selected through evaluation of experts twice. The pilot tests were conducted and targeted at Jeonnam song ho-jung village and Gyeongnam Haegeumgang village to identify derived survey items. In addition, descriptive statistic analysis and reliability analysis were conducted. As a result, survey items were corrected by reducing 10 items of the total 54 items. This results showed that using this tool could help us understand capacity levels of rural residents.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.81-90
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• 2018

Modern investment theory has empirically proved that stock returns can be explained by several factors such as market risk, firm size, and book-to-market ratio. Other unknown factors affecting stock returns are also believed to still exist yet to be found. We believe that one of such factors is the operational efficiency of firms in transforming inputs to outputs, considering the fact that operations is a fundamental and primary function of any type of businesses. To support this belief, this study intends to empirically study the relationship between firm efficiency and stock price performance. Firm efficiency is measured using data envelopment analysis (DEA) with inputs and outputs obtained from financial statements. We employ cross-efficiency evaluation to enhance the discrimination power of DEA with a secondary objective function of aggressive formulation. Using the CAPM-based performance regression model, we test the performance of equally weighted portfolios of different sizes selected based upon DEA cross-efficiency scores along with a buy & hold trading strategy. For the empirical test, we collect financial data of domestic firms listed in KOSPI over the period of 2000~2016 from well-known financial databases. As a result, we find that the porfolios with highly efficient firms included outperform the benchmark market portfolio after controlling for the market risk, which indicates that firm efficiency plays a important role in explaining stock returns.

• Transactions of Materials Processing
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• v.20 no.7
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• pp.473-478
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• 2011

In this study, the performance of a thermo siphon type radiator made of copper for LED lighting system was evaluated by using an inverse heat transfer method. Heating experiments and finite element heat transfer analysis were conducted for three different cases. The data obtained from experiments were compared with the analysis results. Based on the data obtained from experiments, the inverse heat transfer method was used in order to evaluate the heat transfer coefficient. First, the heat transfer analysis was conducted for non-vacuum state, without the refrigerant. The evaluated heat transfer coefficient on the radiator surface was 40W/$m^2^{\circ}C$. Second, the heat transfer analysis was conducted for non-vacuum state, with the refrigerant, resulting in the heat transfer coefficient of 95W/$m^2^{\circ}C$. Third, the heat transfer analysis was conducted for vacuum state, with refrigerant. For the third case, the evaluated heat transfer coefficients were 140W/$m^2^{\circ}C$. Third, the heat transfer analysis was conducted for vacuum state, with refrigerant. For the third case, the evaluated heat transfer coefficients were 140W/$m^2^{\circ}C$ for the radiator body, 5W/$m^2^{\circ}C$. Third, the heat transfer analysis was conducted for vacuum state, with refrigerant for the rising position of radiator pipe, 35W/$m^2^{\circ}C$. Third, the heat transfer analysis was conducted for vacuum state, with refrigerant. For the highest position of radiator pipe, and 120W/$m^2^{\circ}C$ for the downturn position of radiator pipe. As a result of inverse heat transfer analysis, it was confirmed that the thermal performance of the current radiator was best in the case of the vacuum state using the refrigerant.