• Journal of Korea Water Resources Association
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• v.53 no.7
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• pp.507-519
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• 2020

This study developed the radon measurement system that can be used for crustal movement monitoring and seismic occurrence and prediction, and compared and analyzed the results of test-operated radon measurement system and observed seismic occurrence cases. First, the developed radon measurement system consists of an NB-IoT radon measurement device, data center, data analysis, and data supply server. Because the measured radon data can be remotely trasmitted by using NB-IoT, this system is very suitable for installation and operation in unmaaned groundwater station. Second, the developed radon measurement device was test-operated at two groundwater stations in Gimpo from May to July 2019. The measured radon data was compared with the groundwater-level and electrical conductivity measurement data, and it was confirmed that the radon measurement device developed in this study has some potential for commercialization. Finally, from November 2019 to February 2020, three observed seismic cases and daily measured radon, groundwater-level, electrical conductivity data by the NB-IoT radon measurement device installed at three groundwater stations in Pohang, which is a test-bed, were compared and analyzed. As a result of the analysis, it was confirmed that the seismic occurrence correlated with radon, groundwater level, and electrical conductivity and all of these measured data will be able to provide basic data to help in seismic monitoring and prediction in the future.

• Journal of Gastric Cancer
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• v.13 no.4
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• pp.214-225
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• 2013

Purpose: Peritoneal lavage cytology is part of the routine staging workup for patients with advanced gastric cancer. However, no quality assurance study has been conducted to show variations or biases in peritoneal lavage cytology results. The aim of this study was to demonstrate a test execution variation in peritoneal lavage cytology between investigating surgeons. Materials and Methods: A prospective cohort study was designed for determination of the positive rate of peritoneal lavage cytology using a liquid-based preparation method in patients with potentially curable advanced gastric cancer (cT2~4/N0~2/M0). One hundred thirty patients were enrolled and underwent laparotomy, peritoneal lavage cytology, and standard gastrectomy, which were performed by 3 investigating surgeons. Data were analyzed using the chi-square test and a logistic regression model. Results: The overall positive peritoneal cytology rate was 10.0%. Subgroup positive rates were 5.3% in pT1 cancer, 2.0% in pT2/3 cancer, 11.1% in pT4a cancer, and 71.4% in pT4b cancer. In univariate analysis, positive peritoneal cytology showed significant correlation with pT stage, lymphatic invasion, vascular invasion, ascites, and the investigating surgeon. We found the positive rate to be 2.1% for surgeon A, 10.2% for surgeon B, and 20.6% for surgeon C (P=0.024). Multivariate analysis identified pT stage, ascites, and the investigating surgeon to be significant risk factors for positive peritoneal cytology. Conclusions: The peritoneal lavage cytology results were significantly affected by the investigating surgeon, providing strong evidence of test execution variation that could be related to poor diagnostic accuracy and stage migration in patients with advanced gastric cancer.

• Journal of the Korea Fashion and Costume Design Association
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• v.20 no.4
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• pp.41-56
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• 2018

The purposes of this study were to investigate preference of Baekje culture relics and to examine purchasing behaviors of fashion cultural products of adolescents. The subjects were 421 adolescents and measuring instruments consisted of Baekje relics preference items, fashion cultural products purchasing behaviors items, and subject' demographic attributions. The data were analyzed by frequency analysis, $x^2$ test, factor analysis, t-test, ANOVA and Duncan's multiple range test using SPSS program. The results were as follows. First, adolescents were more likely to prefer crown ornaments of the King Muryong in Kongju region, and gilt-bronze incense burner and halo in Buyeo region. Second, as fashion cultural products, adolescents were more likely to prefer T-shirts and accessory items, and modern image. As product selection criteria, they considered aesthetics as the most important factor, followed by symbolism and practicality. Adolescents evaluated the resonable purchase price of fashion cultural products as less than 20,000 won for T-shirts, cap & bag, and less than 10,000 won for accessories. The adolescent's satisfaction of fashion cultural products was low, and the main dissatisfaction was high prices, and the lack of practicality and diversity. Third, the preference for Baekje cultural relics and purchasing behaviors of fashion cultural products differed according to age and sex of adolescents. This study showed that fashion culture products for adolescents need to be designed in a modern sense with a unique cultural symbolism, focusing on T-shirts and accessories items. In addition, fashion cultural products companies should established the product development plan considering the characteristics according to the age and sex of adolescents.

• Journal of Convergence for Information Technology
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• v.11 no.2
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• pp.130-137
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• 2021

The purpose of this study is to explore methods to prevent and improve the problem of overdependence on smartphones by analyzing the differences in satisfaction with college life satisfaction of freshmen. For this, data on freshmen of KCYPS were extracted and used. The data were analyzed using non-hierarchical cluster(K-means) analysis, T-test, one-way ANOVA, and Scheffé tests. The results of this study are as follows. First, it has been shown that freshmen who are overdependent on smartphones experience inconvenience in their daily life, withdrawal and anxiety, and resistance. Second, there is no significant difference in the level of satisfaction with college life according to gender(t=-.015, p<.05). Third, it is shown that the level of satisfaction with college life of overdependent freshmen on smartphone is significantly lower compared to that of average and moderate dependent freshmen. Based on the results, it was suggested that university-level efforts such as emotional support and learning strategy support are needed for freshmen who are overdependent on smartphones.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.2
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• pp.171-176
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• 2016

In this paper, the integration of the firing test stages at the acceptance test of the propelling charge has been studied using statistical analysis on the basis of the test data of K676 and K677 propelling charge for K9 self propelled howitzer. Acceptance test of K676 / K677 propelling charge consists of 3 stages and each stage is charge assessment test, charge uniformity test and charge proving ground test. Many of rounds are fired and much money is spent to prove the charge performance at each stage. The result of t-test shows that there is no difference between charge uniformity and charge proving ground test stage of K676 and K677 propelling charge.

• Journal of Korean Society of Steel Construction
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• v.11 no.2 s.39
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• pp.241-241
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• 1999

The analysis and design of steel frames are usually carried out under the assumption that the connections of beam-to-column are either fully rigid or ideally pinned. However the connections actually show semi-rigid behavior in many cases. The authors investigated the structural behavior of simi-rigid connection with reformed T-stub by using of SM490 steel. The objective of the study is to investigate the structural behavior of the beam-to-column semi-rigid connection with reformed T-stub, which is made of SS400 steel. The beam-to-column connections by using reformed T-stubs were tested under monotonic loading and cyclic loading condition. The possibility of application of semi-rigid connections with reformed T-stubs was ascertained from test results.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.4
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• pp.38-48
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• 1993

A study on friction welding of stainless steel bar(SUS431) to chrome molybdenum steel bar(SCM21) was accomplished experimentally through analysis for relations among friction welding conditions, tension test, hardness test, microstructure test and acoustic emission test. The results obtained are summarized as follows ; 1. Through friction welding of SUS431 bar to SCM21 bar, the optimum welding condition by considering on strength and toughness was found to be the range of heating time of 3-5 sec when the number of rotating speed of 2000rpm, heating pressure of 10kg/$mm^2$, and upsetting time of 4 sec. 2. Quantitative ralationship was identified between heating time($T_1$, sec) and tensile strength (${\sigma},\;kgf/mm^2$) of the friction welded joint and the relation equation is $\sigma$=52.62$T_1{^{0.06}}$. 3. Through AE test, quantitative relationship was confirmed between heating time($T_1$, sec) and total AE(N, counts) during welding, and the relation is computed as follows ; N=30413.6$e^{0.06T1}$. 4. It was confirmed that the quantitative ralationship exists between the tensile strength of the welded joints and AE cumulative counts. And the relation is computed as the following ; ${\sigma}$=16.37(ln N)- 116.4. 5. When ONZ=36500-41500 counts by $OT_1Z$=3~5sec, it was identified by experiment that the range of welded joint tensile strength is 55.6-57.7kgf/$mm^2$/ whose joint efficiency is more than 100%, and it was experimentally confirmed that the real-time nondestructive quality(strength) evaluation for the friction welded joints could be possible by acoustic emission technique.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.3
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• pp.373-384
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• 1999

The purposes of this study were 1) to test the differences between two groups who have high and low purchase of apparel in low-price retailing concerning consumers' beliefs and attitude toward low-prce retailing 2) to identify differences between these two groups in type of information search and use of information sources and 3) to investigate differences between department store and low-price retailing in consumers' satisfaction toward products and purchase frequencies of apparel items and differences between two groups in demographic variables. The data were collected via a self-administeered questionnaire from 474 femail adults in Seoul Korea and analyzed by factor analysis t-test and paired t-test. The results of this study were as follows : First based on a series of t-test and paired t-test. the results showed that those who had a high purchase of apparel in low-price retailing had significantly higher belief scores on all of the five store attributes and a more favorable attitude toward low-price retailing than did those who had low purchase. Second those who had high purchase of apparel in low-price retailing had significantly higher scores on ongoing and prepurchase information search and on use of mass media information and interpersonal information source than did those who had low purchase. Third in case of high purchase consumers of apparel in low-price retailing there were not found significant differences between department store and low-price retailing there were not found significant differences between department store and low-price retailing in purchase frequency on man's and women's casual wear of department stores than low-price retailing. However low purchase consumers of apparel in low-price retailing revealed significantly higher purchase frequency on all of seven apparel items of department stores than low-price retailing. Finally there were significant differences between two groups in demographic variables. The papers discussed theoretical implications as well as manageral implications.

• Journal of the Korean Home Economics Association
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• v.43 no.6 s.208
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• pp.145-169
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• 2005

This study aimed to evaluate Comprehensive Croup Therapy Program developed for children and mothers of divorced families. The research questions were to determine first, any differences between program participants and non-participant in the areas of life wellbeing, attitude towards divorce, self-esteem, and communication skills as a result of this program; and second the durability of these effects three months after implementation of the program. The subjects of this study were 41 children and 14 mothers of the divorced families. Among them, 18 children and 6 mothers, including 5 mother-child dyads were assigned to experimental group, while 23 children and 8 mothers, including 8 mother-child dyads, to control group. Both groups received pre-and post-test evaluation but experimental group additionally received a follow-up test. The data were analyzed by t-test, Mann-Whitney U Test, Wilcoxon Matched-Pairs Signed-Ranks Test and qualitative analysis. The results showed that therapy Program enhanced the life wellbeing of both child and mother participants significantly, and this effect lasted for at least for three months after the termination of the program. Second, though the effects were not statistically significant, child and mother participants' attitude towards divorce, self-esteem, and communication skills between mother and child changed positively after the program and these effects lasted for over three months.

• Journal of the Korea Safety Management & Science
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• v.15 no.3
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• pp.51-60
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• 2013

With the recent changes in the environment of weapon systems acquisition, the systems development is becoming more susceptible to a variety of risks. To cope with this situation, US DoD has been emphasizing the importance of constantly applying the test and evaluation (T&E) process throughout the whole life cycle of the weapon systems. In particular, the safety requirements are called for attention while dealing with system risks. To this end, the present paper is aimed at studying the T&E process which incorporates the systems safety in weapon systems development. Analyzing and modeling the relevant processes has made it possible to achieve the objective. As a case study, the model results were applied to the development of unmanned aerial vehicles.