• Journal of the Society of Disaster Information
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• v.20 no.1
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• pp.169-176
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• 2024

Purpose: In this paper, an experimental study was conducted to analyze the difference in shear strength caused by the problem of excluding coarse particles due to the size of the test specimen in the direct shear test. Method: A large-scale direct shear test was conducted on three weathered soils containing coarse aggregates with a maximum diameter of 50mm. In addition, a small-scale direct shear test was performed using a sample with a maximum diameter of 5 mm, excluding coarse aggregates. Result: In the case of the small-scale direct shear test, compared to the results of the large-scale direct shear test containing large particles, the internal friction angle was about 2.3% smaller, and there was no significant difference. In terms of cohesion, compared to the large-scale direct shear test, the small-scale direct shear test derived about 80.3% smaller value, showing a relatively large difference. Conclusion: In the large-scale direct shear test, it was analyzed that the coarse particles had a greater impact on the cohesion than the internal friction angle. Therefore, granite weathered clay containing coarse particles is judged to have the same shear strength as the cohesive force that is not affected by vertical stress. In this study, it was analyzed that the small-scale direct shear test, which excludes the coarse particles that are commonly used, provides results on the safety side by excluding the effect of coarse particles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.76-91
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• 2019

There have been many studies to examine the patterns in innovations reflecting industry-specific characteristics from an evolutionary economics perspective. The purpose of this study is to identify industry-specific differences in product innovation patterns and determinants of innovation performance. For this, Korean manufacturing is classified into high-tech industries and low-tech industries according to technology intensity. It is also pointed out that existing research does not reflect the decision-making process of firms' R&D implementations. In order to solve this problem, this study presents a Heckman sample selection model and a double-hurdle model as alternatives, and analyzes data from 1,637 firms in the 2014 Survey on Technology of SMEs. As a result, it was confirmed that the determinants and patterns of manufacturing in small and medium-size enterprise (SME) product innovation are significantly different between high-tech and low-tech industries. Also, through an extended empirical model, we found that there exist a sample selection bias and a hurdle-like threshold in the decision-making process. In this study, the industry-specific features and patterns of product innovation are examined from a multi-sided perspective, and it is meaningful that the decision-making process for manufacturing SMEs' R&D performance can be better understood.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.16 no.2
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• pp.153-159
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• 2005

Autistic disorder and other PDD are currently viewed as a largely genetically determined neurodevelopmental disorder, although its underlying biological causes remain to be established. In this review, we examine the available neurodevelopmental literature on autistic disorder and discuss the findings that have emerged. Typical neuropathological observations are rather consistent with respect to the limbic system (increased cell packing density and smaller neuronal size), the cerebellum (decreased number of Purkinje cells) and the cerebral cortex ($>50\%$ of the cases showed features of cortical dysgenesis). However, most of the reported studies had to contend with the problem of small sample sizes, the use of quantification techniques, not free of bias and assumptions, and high percentages of autistic subjects with comorbid mental retardation or epilepsy. Furthermore, data from the limbic system and on age-related changes lack replication by independent groups. It is anticipated that future neuropathological studies held great promise, especially as new techniques such as design-based stereology and gene expression are increasingly implemented and combined, larger samples are analysed, and younger subjects free of comorbidities are investigated.

• The Korean Journal of Applied Statistics
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• v.22 no.4
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• pp.793-804
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• 2009

The hypotheses of difference, ratio and odds ratio between two proportions are used for the non-inferiority trial. The approximate unconditional test suggested by Kang and Chen (2000) based on difference and ratio have the potential problem against the failure rate. When the sample size is small, the type I errors of the asymptotic test using the normal approximation suggested by Chen et al. (2000) tends to exceed the nominal level. Therefore, we propose the approximate unconditional test based on odds ratio and compare the test with the asymptotic test. And we compare the three hypotheses used in the approximate unconditional tests of two proportions with respect to the type I errors and power.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.2
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• pp.723-726
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• 2013

Background: Breast cancer is worldwide the most common cancer in women and is a major public health problem. Genes with high or low penetrance are now clearly implicated in the onset of breast cancer, mostly the BRCA genes. All women in families at high risk of breast cancer do not develop tumours, even when they carry the familial mutation, suggesting the existence of genetic and environmental protective factors. Several studies have shown that consanguinity is linked to a decreased or an increased risk of breast cancer, but to the best of our knowledge, there is no study concerning the association between consanguinity and the occurrence of tumours in women with high risk of breast cancer. The objective of this study was to examine whether parental consanguinity in families with genetic predisposition to breast cancer affect the risk of siblings for having this cancer. Materials and Methods: Over a six-year period, 72 different patients with a histological diagnosis of breast or ovarian cancer from 42 families were recruited for genetic counselling to the Department of Medical Genetics, Rabat. Consanguinity rate was determined in cases and compared to the consanguinity rate in the Moroccan general population. Results: Consanguinity rates were 9.72% in patients and 15.3% in controls, but the difference was statistically not significant (p>0.001) and the mean coefficient of consanguinity was lower in breast cancer patients (0.0034) than in controls (0.0065). Conclusions: Despite the relatively small sample size of the current study, our results suggest that parental consanguinity in Moroccan women might not be associated with an altered risk of breast cancer. Large scale studies should be carried out to confirm our results and to develop public health programs.

• The Korean Journal of Applied Statistics
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• v.26 no.3
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• pp.431-440
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• 2013

We consider the problem of estimating the parameters of heavy tailed distributions. In general, maximum likelihood estimation(MLE) is the most preferred method of parameter estimation because it has good properties such as asymptotic consistency, normality and efficiency. However, MLE is not always the best solution because MLE is unstable or does not exist in some cases. This paper proposes another parameter estimation method, non-linear least squares(NLS) and compares its performance to MLE. The NLS estimator is achieved by minimizing sum of squared difference between empirical cumulative distribution function(CDF) and a theoretical distribution function. In this article, we compare the NLS method to MLE using simulated data from heavy tailed distributions. The NLS method is shown to perform better than MLE in Burr distribution when the sample size is small; in addition, it performs well in a Frechet distribution.

• Journal of Digital Convergence
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• v.11 no.1
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• pp.61-74
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• 2013

In digital age export expansion is the key fact of promoting Korea's economic growth. The policy that encourages exportation is being more emphasized to develop of the nation's economy. From the 90's, regionalism has been widespread throughout the world with globalization and internationalization led by WTO and FTA. The world is now becoming one economic bloc. It is necessary to understand how enterprises contribute to the exportation to establish and manage the policy that encourage and support the exportation. This study estimates SME's level of contribution on gross exports and understands the problem, while looking for better statistical alternatives and finding SME's export energizing policies. It is estimated that domestic SMEs contribute about 40-50% of gross exports. SME bureau and national statistical office should select optimal size of population of each industry, design and extract sample to conduct the export related survey extensively. SMEs should analyze the product and skills of the industry that is dominated by major companies to contribute to the exportation more efficiently. This effort will increase the level of contribution to gross exports in general.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.5-9
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• 2004

In this paper, we studied the OCT(Optical Coherence Tomography) system which it has been extensively studied because of having some advantages such as high resolution cross-sectional images, low cost, and small size configuration. A basic principle of OCT system is Michelson interferometer. The characteristics of light source determine the resolution and the transmission depth. As a results, the light source have a commercial SLD with a central wavelength of 1,285 nm and FWHM(Full Width at Half Maximum) of 35.3 nm. The optical delay line part is necessary to equal of the optical path length with scattered light or reflected light from sample. In order to equal the optical path length, the stage which is attached to reference mirror is moved linearly by step motor And the interferometer is configured with the Michelson interferometer using single mod fiber, the scanner can be focused of the sample by using the reference arm. Also, the 2-dimensional cross-sectional images were measured with scanning the transverse direction of the sample by using step motor. After detecting the internal signal of lateral direction at a paint of sample, scanner is moved to obtain the cross-sectional image of 2-demensional by using step motor. Photodiode has been used which has high detection sensitivity, excellent noise characteristic, and dynamic range from 800 nm to 1,700 nm. It is detected mixed small signal between noise and interference signal with high frequency After filtering and amplifying this signal, only envelope curve of interference signal is detected. And then, cross-sectional image is shown through converting this signal into digitalized signal using A／D converter. The resolution of the OCT system is about 30$\mu\textrm{m}$ which corresponds to the theoretical resolution. Also, the cross-sectional image of ping-pong ball is measured. The OCT system is configured with Michelson interferometer which has a low contrast because of reducing the power of feedback interference light. Such a problem is overcomed by using the improved inteferometer. Also, in order to obtain the cross-sectional image within a short time, it is necessary to reduce the measurement time for improving the optical delay line.

• Journal of Oriental Neuropsychiatry
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• v.33 no.1
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• pp.1-19
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• 2022

Objectives: The objective of this study was to confirm the Chiljeong (七情) characteristics of Hwa-byung patients using the core seven-emotions inventory-short form. Methods: We conducted a retrospective observational study based on the electronic medical records from a Korean medicine hospital. We included patients who were diagnosed with Hwa-byung and examined with Core Seven-Emotions Inventory-short Form (CSEI-S) during hospitalization periods. We presented the characteristics of Hwa-byung by demographic information, CSEI-S, Hwa-byung scale, and Korean Symptom Checklist 95. A correlation analysis was performed between CSEI-S and other clinical and psychological characteristics. Results: The Chiljeong characteristics of Hwa-byung were high in the order of Sorrow (悲), Thought (思), Fear (恐), Fright (驚), Depression (憂), Joy (喜), and Anger (怒). There was no significant difference between each emotion. After combined Korean medical treatment, Sorrow (悲) and Thought (思) significantly decreased. There were static correlations between sorrow (悲) and fright (驚), thought (思) and sorrow (悲), depression (憂) and sorrow (悲), depression (憂) and fright (驚), thought (思) and depression (憂), fear (恐) and fright (驚), anger (怒) and thought (思), thought (思) and fright (驚), sorrow (悲) and fear (恐). Sorrow (悲) and Hwa-byung characteristics scale showed static correlation. Joy (喜) showed a static correlation with disharmony between the heart and kidney scores of the Hwa-byung pattern identification. Between KSCL-95 and CSEI-S, static correlation appeared in depression (憂) with depression, anxiety, and sleep problem scale, sorrow (悲) with depression and anxiety, fright (驚) with depression and obsessive symptoms. Conclusions: Despite several limitations due to the study design and small sample size, this research successfully used CSEI-S to study the Chiljeong (七情) characteristics of Hwa-byung for the first time.

• Journal of Biosystems Engineering
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• v.6 no.2
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• pp.20-32
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• 1982

This survey was conducted to investigate the present status of farm tractor utilization for obtaining a basic reference to the establishment of the government's agricultural mechanization strategies. Thirty two counties from the eight provinces except Jeju were covered in this study. From these selected areas, 433 sample farms having farm tractor were taken to obtain the general informations by the enquete, and 93 sample farms among them to investigate the status of daily tractor use in the year of 1980. The analyzed results are summarized as follows: 1. Farm tractors owned by the rice-oriented farms holds 71.5 percent of the total number of tractors the livestock-oriented farms 17.0 percent, and the orchard-oriented farms 7.0 percent. Among the farm tractors 64.3 percent was a large size (46ps) and 35.7 percent a small size(19~23ps). 2. Most of the tractors surveyed were equipped with the essential attachments such as plow and rotavator. About 18 percent of the tractor owners had no trailer, which seemed too high considering the large percentage of tractor use for transportation. The availability of other attachments was very low except a grader on the rice-oriented farms and a hay harvester and a front loader on the livestock-oriented farms. 3. The average size of farm was 3.9 hectare for the rice-oriented farms, 13.9 hectare for the livestock-oriented farms and 7.4 hectare for the orchard-oriented farms. It was obious that the average farm size of was too small compared to the theoretical machine capacity of the tractors. 4. About 70 percent of the tractor operators were in the age of twenties and thirties. About 90 percent of them had an educational level of middle school graduate or above even though their technical level was very low. 5. Any particular problem in tractor use was not found in this survey. From the farmer's preference for purchasing a new tractor, however, it is estimated the demand on a 20-30ps tractor will be more increased. 6. The average annual use of tractor was of about 100 days or 400 hours. It appeared that the rice-oriented farms used most with 412.4 hours per year, and followed by the livestock-oriented farms with 403.6 hours, the orchard oriented farms with 377.7 hours. 7. Among the total hours of tractor use, 47.3 percent was for transportation, and 41.6 percent was for plowing and rotary tillage. The largest portion of the annual tractor use was taken by transportation on the livestock-oriented farms, by land preperation on the rice-oriented farms, and by loading and chemical spraying on the orchard-oriented farms. 8. The hours of tractor use had a peak in May. The hours of use for own farm was remarkably different among the different farm oriented, but there was no considerable difference between the too different sizes of tractor. 9. The hours of tractor use decreased as the age of the operator or the educational level increased. The reason might be that the operators who had a high educational level or were older had a tendency of disliking custom works. 10. The average custom use of tractor was 171.3 hours per year, and the ratio of custom work was 63.7 percent on the rice-oriented farms, 31.7 percent on the livestock-oriented farms and 22.4 percent on the orchard-oriented farms. Among the custom works, the most popular one was the grader leveling. 11. The charge on custom work was about 40,000 Won per hectare for plowing and rotary tillage, and it was the most expensive in the southeastern region, and next followed by the southwestern region. 12. The average plowing capacity of the small tractor was 7.8 hours per hectare in the paddy field, and that of the large tractors was 4.3 hours per hectare. The average rotary-tilling capacities of the small and the large tractors were 6.5 and 4.3 hours per hectare, in the paddy field respectively.