• ETRI Journal
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• v.45 no.4
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• pp.704-712
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• 2023

This paper presents a flexible finite-difference technique for analyzing the nonuniform guiding structures. Because the voltage and current variations along the nonuniform structure differ for each segment, this work considers the adaptable discretization steps. This technique increases the accuracy of the final response. Moreover, by applying the singular value decomposition and discarding the nonprincipal singular values, an optimal lower rank approximation of the discretization matrix is obtained. The computational cost of the introduced method is significantly reduced using the optimal discretization matrix. Also, the proposed method can be extended to the nonuniform waveguides. The technique is verified by analyzing several practical transmission lines and waveguides with nonuniform profiles.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.2_1
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• pp.297-306
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• 2024

This study identified the power distance tendency of firefighters. Power distance propensity is one of the important organizational and cultural factors that influence the development of the organization. There is a big difference in the attitude of the members of the organization to perform their work according to the tendency of the distance of power. As a result of the main study, the overall level of power distance propensity of the subjects was 2.55 points on average. In particular, there was a significant difference in the propensity of power distance according to class (p<0.05). In the future, it is necessary to study the effect of job characteristics according to the rank of firefighters on the propensity to distance power. It is expected to form a positive organizational culture of the firefighting organization by utilizing the power distance tendency of the members of the organization.

• Restorative Dentistry and Endodontics
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• v.49 no.2
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• pp.21.1-21.8
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• 2024

Objectives: This paper aims to serve as a useful guide for sample size determination for various correlation analyses that are based on effect sizes and confidence interval width. Materials and Methods: Sample size determinations are calculated for Pearson's correlation, Spearman's rank correlation, and Kendall's Tau-b correlation. Examples of sample size statements and their justification are also included. Results: Using the same effect sizes, there are differences between the sample size determination of the 3 statistical tests. Based on an empirical calculation, a minimum sample size of 149 is usually adequate for performing both parametric and non-parametric correlation analysis to determine at least a moderate to an excellent degree of correlation with acceptable confidence interval width. Conclusions: Determining data assumption(s) is one of the challenges to offering a valid technique to estimate the required sample size for correlation analyses. Sample size tables are provided and these will help researchers to estimate a minimum sample size requirement based on correlation analyses.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.8
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• pp.2137-2156
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• 2024

Customer reviews are the second-most reliable source of information, followed by family and friend referrals. However, there are many existing customer reviews. Some online shopping platforms address this issue by ranking customer reviews according to their usefulness. However, we propose an alternative method to rank customer reviews, given that this system is easily manipulable. This study aims to create a ranking model for reviews based on their usefulness by combining product and seller service aspects from customer reviews. This methodology consists of six primary steps: data collection and preprocessing, aspect extraction and sentiment analysis, followed by constructing a regression model using random forest regression, and the review ranking process. The results demonstrate that the ranking model with service considerations outperformed the model without service considerations. This demonstrates the model's superiority in the three tests, which include a comparison of the regression results, the aggregate helpfulness ratio, and the matching score.

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.40-48
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• 2001

For a Liquified Petroleum Gas(LPG) station, the reliability analysis, such as Fussell-Vesely importance, risk decrease factor and risk increase factor, was carried out and the risk ranks of events were determined. In order to confirm the degree of the risks identified in the reliability analysis, the quantitative risk analysis was done for the equipments which had the large values of risk ranks. As a result of the importance analysis for the LPG station, the external event was identified as the most riskful event. The defect of construction structure and the pipe corrosion were riskful as well. The result of quantitative risk analysis showed that the length of 46.3 meters were estimated to damage the process equipments by the thermal flux from the catastrophic rupture of storage tank in Boiling Liquid Expanding Vapor Explosion.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.4
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• pp.1171-1176
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• 2012

Objective: The current study aimedto screen for possible factors which affect prognosis of chondrosarcoma. Methods: Thirty seven cases were selected and analyzed statistically. The patients received surgical treatment at our hospital between December 2005 and March 2008. All of them had complete follow-up data. The survival rates were calculated by univariate analysis using the Kaplan-Meier method and tested by Log-rank. ${\chi}^2$ or Fisher exact tests were carried out for the numeration data. The significant indexes after univariate analysis were then analyzed by multivariate analysis using COX regression model. Based on the literature, factors of gender, age, disease course, tumor location, Enneking grades, surgical approaches, distant metastasis and local recurrence were examined. Results: Univariate analysis showed that there were significant differences in Enneking grades, surgical approaches and distant metastasis related to the patients' 3-year survival rate after surgery (P<0.001). No significant difference was not found in gender, age, disease course, tumor location or local recurrence (P>0.05). Multivariate analysis showed that Enneking grade (P=0.007) and surgical approaches (P=0.010) were independent factors affecting the prognosis of chondrosarcoma, but distant metastasis was not (P=0.942). Conclusion: Enneking grades, surgical approaches and distant metastasis are risk factors for prognosis of chondrosarcoma, among which the former two are independent factors.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.5
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• pp.284-291
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• 2022

Objectives: This study aimed to analyze the clinicopathological prognostic factors affecting the survival of patients with oral squamous cell carcinoma (OSCC). Materials and Methods: A retrospective study was conducted on patients with OSCC who received treatment at the Oral Oncology Clinic of the National Cancer Center (NCC) from June 2001 to December 2020. The patients' sex, age, primary site, T stage, node metastasis, TNM staging, perineural invasion (PNI), lymphovascular invasion (LVI), differentiation, surgical resection margin, smoking, and drinking habits were investigated to analyze risk factors. For the univariate analysis, a Kaplan-Meier survival analysis and log-rank test were used. Additionally, for the multivariable analysis, a Cox proportional hazard model analysis was used. For both analyses, statistical significance was considered when P<0.05. Results: During the investigation period, 407 patients were received surgical treatment at the NCC. Their overall survival rate (OS) for five years was 70.7%, and the disease-free survival rate (DFS) was 60.6%. The multivariable analysis revealed that node metastasis, PNI, and differentiation were significantly associated with poor OS. For DFS, PNI and differentiation were associated with poor survival rates. Conclusion: In patients with OSCC, cervical node metastasis, PNI, and differentiation should be considered important prognostic factors for postoperative survival.

• Journal of Korean Society of Archives and Records Management
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• v.5 no.1
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• pp.79-105
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• 2005

This study is that the name from Tagjijunjeol is compared with the actual papers used in historical documents. I have selected the families having had influencing power in Gyungi-Do(京畿道), Gyungsang-Do(慶尙道), Jeonra-Do(全羅道), Chungcheung-Do(忠淸道), and analyzed 1504 articles of historical documents owned by those families. I checked up each papers used in historical documents in it's shape of screens, density, raw material. I cannot find the feature of it's region, but prominent feature according to the types and period of historical documents. At first, I have surveyed the impressions of screen marks in papers. The number of strips can be divided into two cases, around 10 and around 17. The case around 17 is similar to the number seen in the book paper of the early Joseon Dynasty, but the case around 10 is rare. Dard Hunter said in his book, published in 1933, that screens were made of Korean grass(Miscanthus sp.) at that time in Korea. I guess the impressions of screen marks of the case around 10 was made of Korean grass, Miscanthus sp.. The case around 10 and the case around 17 were not different in period, but the contemporary appearance. However, if we look into the change of strips' number, we can learn that it becomes more dense as time goes by. The intervals of hair stitch, contrary to book paper, have appeared irregularly and a short hair stitch was frequently found between long hair stitches. This was the result of fastening extra stitch to increase the firmness of strips, as the part of screens which was frequently touched by hands would wear out easily. Then, have look into the density. Each kinds of historical documents had a wide range of density. But the average have had relationship with the kinds of paper written in Tagjijunjeol. The historical documents having the same item of paper have kept similar densities. From the density variation of Gosingyoji(告身敎旨), the letter of appointment the official rank over 5 by king, based on time periods, we can see a great disparity between before and after Imjin-waeran war. Before Imjin-waeran war paper's quality was high, right after Imjin-waeran war went abruptly down, and went gradually up just from 1650's, but since 1700's quality has not risen more, kept the value. On the contrary, the density of Gyocheop(敎牒), the letter of appointment the official rank under 5 by the Ministry of Personnel and the Ministry of Military, have not had a great disparity according to time periods, but had a lower density than Gosingyoji. Joseon Dynasty has strictly divided Gosingyoji appointing the official rank over 5 from Gyocheop appointing the official rank under 5, it seems to distinguish the appointment by king from the appointment by Ijo(吏曹), the Ministry of Personnel and Byeongjo(兵曹), the Ministry of Military.

• Fashion & Textile Research Journal
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• v.7 no.4
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• pp.413-418
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• 2005

The purpose of this study was for the adult woman that provides the investigation, analysis, consideration of the relationship with clothing behavior and self-efficacy depends on their skin care grade. Data were collected from 477 adult females and analyzed by using frequency, dispersion analysis, ANOVA, t-test, Duncan test utilizing SPSS 10.0 program. The results were as follows: The younger and the more educated respondents were the better their skin care. Also, the more they spent on clothes, the more they spent on cosmetic products. For occupations, professionals were to have better skin care. It was expose that 20s and 30s are shown difference for all low rank leading persons except conformity in the midst of it is clothing behavior main point by skin care management degree, 40s appeared that difference is seen in interest, psychological dependence, aesthetics, management. It was expose that difference does not exist in liver that is clothing behavior main point by skin care administration degree in 50s. 20s appeared difference in general self-efficacy divination in self-efficacy, and 30s appeared that skin care degree is high as general self-efficacy and physical self-efficacy are high. It was expose that 40s and 50s are no difference of self-efficacy in between group by skin care degree.

• Korean Journal of Agricultural Science
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• v.45 no.3
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• pp.547-559
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• 2018

Consumers are becoming increasingly interested in what kind of value their food has. Many studies have focused on consumers' preferences and willingness to pay for specific food values. However, few studies have asked consumers to consider or rank the importance of different food values. This paper determined consumers' food values by implementing the best-worst scaling approach and segmented consumers based on the relative importance of general food values that consumers place on them. Among a list of eleven food values (taste, safety, origin, appearance, price, environmental impact, naturalness, convenience, nutrition, fairness, and habit) which was compiled from previous studies on food preferences, on average, safety, nutrition, taste, and price were the most important values to consumers, whereas fairness, habit, appearance, convenience, origin, and environmental impact were the least important values. However, significant variation exists among consumers in terms of the relative importance of food values. To investigate the heterogeneity among consumers, a Latent Class Analysis was performed to classify consumers into subgroups based on responses to questions. Two latent classes were found and characterized as 'safety-nutrition' and 'taste-price'. The 'safety-nutrition' cluster represents 61% of the sample and a group of people who find safety and nutrition centered values to be the most important. Another cluster represents about 39% of the sample, and relative to the first group, this group finds price and taste values to be more important.