• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.352-360
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• 2008

Recently Task Group (TG) 4 of the Institute of Electrical and Electronics Engineers (IEEE) 802.15a has been recommended a system with ranging capability in existence of multiple Simultaneous operating piconets (SOPs) as well as low-cost, low-power. According to the ranging service, coherent and non-coherent based ranging schemes using ternary code have been adopted as a standard. However it is hard to estimate an accurate time of arrival (TOA) in case of using direct sequence based TOA estimation method because pulse repetition interval (PRI) offered by TG is more limited than the maximum excess delay (MED) of channel. To mitigate inter pulse interference (IPI) problem, this paper proposes a non-coherent TOA estimation scheme using non-periodic transmission (NPT) pattern. The proposed receiver is based on a non-coherent energy detection considering with motivation of low rate wireless personal area network (LR-WPAN). TOA information is estimated via proper comparison with a prescribed threshold after the sliding correlation and search back window (SBW) process for reducing TOA error. To verify the performance of proposed ranging scheme, two distinct channel models approved by IEEE 802.15.4a TG are considered. According to the simulation results, we could conclude that the proposed scheme have performed better performance than the conventional method on the existence of multiple SOPs.

• Journal of Industrial Convergence
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• v.21 no.4
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• pp.65-72
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• 2023

This study's purpose is to verify how the periodically designated auditor in the recently implemented periodic auditor designation system affects audit quality. In this study, hypotheses were established by reviewing previous studies, and 980 samples of 2019 and 2020 were selected for KOSPI-listed companies. Dechow & Dichev (2002)'s accrual quality was used as the dependent variable, and the effect of whether or not a company was periodically designated as an auditor and whether or not a Big 4 auditor was selected was empirically analyzed. As a result of the analysis and correlation analysis, a statistically significant difference was confirmed in the quality of the dependent variable accrual and the independent variable designated auditor (PA). However, as a result of the regression analysis model 1, it was found that the designated auditor was not significant, but it was confirmed that there was a significant difference in the control variables. Further analysis confirmed the difference in audit quality according to the Big 4 auditors. This study is significant in that it is a study that uses empirical data to study the effect of audit quality and the selection of regularly designated auditor companies after the introduction in 2019 and 2020. Due to the non-disclosure of government-designated companies, there is a limit that there may be a difference from the selection based on the researcher's published selection criteria.

• Korean Journal of Radiology
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• v.23 no.1
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• pp.30-41
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• 2022

Objective: Computed tomography enterography (CTE) and magnetic resonance enterography (MRE) are considered substitutes for each other for evaluating Crohn's disease (CD). However, the adequacy of mixing them for routine periodic follow-up for CD has not been established. This study aimed to compare MRE alone with the mixed use of CTE and MRE for the periodic follow-up of small bowel inflammation in patients with CD. Materials and Methods: We retrospectively compared two non-randomized groups, each comprising 96 patients with CD. One group underwent CTE and MRE (MRE followed by CTE or vice versa) for the follow-up of CD (interval, 13-27 months [median, 22 months]), and the other group underwent MRE alone (interval, 15-26 months [median, 21 months]). However, these two groups were similar in clinical characteristics. Three independent readers from three different institutions determined whether inflammation had decreased, remained unchanged, or increased within the entire small bowel and the terminal ileum based on sequential enterography of the patients after appropriate blinding. We compared the two groups for inter-reader agreement and accuracy (terminal ileum only) using endoscopy as the reference standard for enterographic interpretation. Results: The inter-reader agreement was greater in the MRE alone group for the entire small bowel (intraclass correlation coefficient [ICC]: 0.683 vs. 0.473; p = 0.005) and the terminal ileum (ICC: 0.656 vs. 0.490; p = 0.030). The interpretation accuracy was higher in the MRE alone group without statistical significance (70.9%-74.5% vs. 57.9%-64.9% in individual readers; adjusted odds ratio = 3.21; p = 0.077). Conclusion: The mixed use of CTE and MRE was inferior to MRE alone in terms of inter-reader reliability and could probably be less accurate than MRE alone for routine monitoring of small bowel inflammation in patients with CD. Therefore, the consistent use of MRE is favored for this purpose.

• Journal of Korean society of Dental Hygiene
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• v.6 no.2
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• pp.129-141
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• 2006

This study attempts to provide basic information that is necessary to establish the direction of oral health education process abd to develop effective oral health promoting programs for college students by analyzing the modifying factors that may affect their oral health behaviors and their cognitive and perceptive factors. Data for this study are collected by the questionnaire method from college students who attend colleges located Chungchong and Busan province for the period between June 20, 2006 and July 30, 2006. The respondents were chosen from Dental department and Non-Dental department. After omitting the responses with insufficient information, 409 valid responses are used for this analysis. The major finding of the present study are as follows: 1. Oral health behaviors factor is higher rate dental department than non-dental department, dental department than non-dental department appear significant the oral health education, the lasted year round oral examination, the used of oral hygiene supplies, oral prevention treatment. 2. Oral health behaviors and perception-awareness factor is higher score dental department than non-dental department and self efficiency is similar. Oral health behaviors is higher score dental department, the barriers to oral health behaviors is similar. The benefits of oral health behavior is higher score dental department. 3. The oral health behavior is higher dental department. In dental department the overall average score for oral health behaviors question is the correct teeth-brushing, self-restraint of liquor and cigarettes. Non dental department the overall average score for oral health behaviors question is the correct teeth brushing, good nutrition. The lower average score is scaling and periodic oral examination. 4. The correlation coefficient analysis between oral health behaviors and perception-awareness factors, variables which appear significant correlation coefficient by the self-efficiency are the control of oral health, the benefits of oral health behaviors, behavior of oral health, variables which appear significant correlation coefficient by the control of oral health are the benefits of oral health behaviors, the knowledge of oral health, behavior of oral health. And variables which appear significant correlation coefficient by the barriers to oral health behaviors is the benefits of oral health behaviors, variables which appear significant correlation coefficient by the knowledge of oral health is oral health behaviors.

• Research in Community and Public Health Nursing
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• v.9 no.2
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• pp.350-361
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• 1998

In an attempt to examine the risk factors and analyze an odds ratio for risk factors associated with mild and moderate. severe hypertension, this study was carried out from August, 1987 to September, 1997. From periodic health examinations of insured adults, 747 subjects were assigned to nomotensives, mild hypertensives and moderate' severe hypertensives. Major findings obtained from the study are as follows: 1. The Body mass index(BMI) was revealed a significant difference among the 3 groups. Also, there was a significant positive correlation between the BMI and systolic, dyastolic blood pressure. 2. Cholesterol was revealed to be significantly different among the 3 groups. Also, there was a significant positive correlation between the cholesterol and systolic, dyastolic blood pressure. 3. Urine protein and a cardiovascular family history was revealed to be significantly different among the 3 groups. The presence of urine protein and cardiovascular family history were significantly higher in hypertensives than nomotensives. 4. A preference for salty food, a preference for flesh and the frequency of flesh eating were not significantly different among the 3 groups. 5. Smoking habits, frequency and duration of cigarette smoking were not significantly different among 3 groups. 6. The habit of alcohol consumption and the frequency and duration of alcohol consumption were not significantly different among the 3 groups. 7. The habit of exercise and its frequency and duration were not significantly different among the 3 groups. 8. Statistically significant elevated odds ratios were noted in the following BMI(mild hypertensives; 2.48, moderate. severe hypertensives ; 4.65), urine protein(mild hypertensives ; 2.37, moderate. severe hypertensives; 6.77), cholesterol(moderate. severe hypertensives ;1.64), cardiovascular family histoy(moderate severe hypertensives; 4.77). Based on these results, the significant risk factors of mild, moderate. severe hypertension were BMI, cholesterol, urine protein, and family history, but diet, smoking, alcohol consumption, and exercise had no significant association.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2002.11a
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• pp.407-411
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• 2002

Ternary sequences are digital codes consisting of discrete values -1, 0, and 1 only. They are advantageous in that the correlation can be carried out using additions only. Also, they feature an ideal circular autocorrelation function, but in channel characterization tasks, the usual requirement is that the linear autocorrelation function be ideal, i.e., a Kronecker delta function. In this article, we consider two approaches to improving their linear autocorrelation or crosscorrelation properties: one is an inverse filtering method with thresholding, and the other is a singular value decomposition (SVD) method. Both methods are simulated under noisy circumstances. The inverse filtering method resulted in an improvement in peak sidelobe level of about 11 dB at an SNR of 30 dB, and the SVD method showed similar performances, albeit more sensitive to noise depending on the singular value selection strategy.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.6
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• pp.48-59
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• 2000

Eigendecomposition based direction-of-arrival(DOA) estimation algorithm such as MUSIC(multiple signal classification) is known to perform well and provide high resolution in white noise environment. However, its performance degrades severely when the noise process is not white. In this paper we consider the DOA estimation problem in a colored noise environment as a problem of extracting periodic signals from noise, and we take the problem to the wavelet domain. Covariance matrix of multiscale components which are obtained by taking wavelet decomposition on the noise has a special structure which can be approximated with a banded sparse matrix. Compared with noise the correlation between multiscale components of narrowband signal decays slowly, hence the covariance matrix does not have a banded structure. Based on this fact we propose a DOA estimation algorithm that transforms the covariance matrix into wavelet domain and removes noise components located in specific bands. Simulations have been carried out to analyze the proposed algorithm in colored noise processes with various correlation properties.

• Journal of the Korean Society of Clothing and Textiles
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• v.39 no.2
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• pp.204-216
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• 2015

Fashion is changing and evolving everyday with an influence from and over contemporary socio-cultural factors. Cartoons expressing the phenomena of times through exchanges of mutual effects with socio-cultural factors that result from functionality and media characteristics. This study examines how fashion provides a great correlation with society-culture expressed in cartoons. The research segment of this study was conducted with literature and case studies; in addition, the UK cartoon magazine "Punch" was selected for the case study. The research findings of the fashion satire expression in cartoon were divided into 2 cases. The first case is that fashion was used as an instrument to satirize socio-cultural phenomena in cartoons. Various fashion elements (hats, dresses, words on T-shirts) were used for satiric expressions and to express periodic images related to politics, economics, society and culture. It communicated factually or criticized noteworthy phenomenon or age changes through the symbolism of fashion. The second case is that fashion itself is the object of satire in a cartoon. It satirically described the blind following and destruction of stereotype as direct objects. Fashion satire appeared in cartoons regardless of a correlation with age. Each cartoon fashion satire had meaning in both humor and criticism for satirizing the age. This study shows that fashion symbolism for satire of the reality has been used as the instrument of expression and simultaneously expressed as the object of the critique as an image and phenomenon that reflects reality. This study has significance in that it examined expressive modes of fashion satire in cartoons that escape from separating fashion from cartoon as a different area.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2002.11a
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• pp.407-411
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• 2002

Ternary sequences are digital codes consisting of discrete values -1, 0, and 1 only. They are advantageous in that the correlation can be carried out using additions only Also, they feature an ideal circular autocorrelation function, but in channel characterization tasks, the usual requirement is that the linear autocorrelation function be ideal, i.e., a Kronecker delta function. In this article, we consider two approaches to improving their linear autocorrelation or crosscorrelation properties: one is an inverse filtering method with theresholding and the other is a singular value decomposition (SVD) method. Both methods are simulated under noisy circumstances. The inverse filtering method resulted in an improvement in peak sidelobe level of about 1㏈ at an SNR of 30㏈, and the SVD method showed similar performances, albeit more sensitive to noise depending on the singular value selection strategy.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.5
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• pp.331-338
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• 2020

In this study, the characteristic of a 3-D micro-woven material, which is one of the newly developed periodic open-cell structure, is analyzed through various computational simulations. To increase the accuracy of the numerical simulations, the distance between each directional wire is parameterized using six design variables, and its model geometry is precisely discretized using tetrahedron elements. Using the improved computational model, the material properties of the mechanical, thermal, and fluidic behavior are investigated using commercial software and compared with the previous experimental results. By changing the space between the x- and y-directional wires, a parametric test is performed to determine the tendency of the change in the material properties. In addition, the correlation between two different material properties is investigated using the Ashby chart. The result can further be used in determining the optimal pattern and wire spacing in 3-D micro-woven materials.