• Journal of the Korean Society of Safety
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• v.16 no.3
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• pp.12-18
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• 2001

The objective of the present work is to examine the effect of inclined angle of channel with multi heat source on thermal stability of electronic equipment. The heat sources are mounted on both sides of channel walls by two kinds of configuration such as the zig-zag md symmetric on. Conductive heat transfer was estimated by using of thermocouples and heat flux sensor. Thus, convective heat transfer and mean Nusselt number could be obtained. With increased inclined angle, the convective heat transfer coefficient was decreased. When inclined angle was smaller than 30 degree, The average Nusselt number of Big-zag configuration was larger than that of symmetric. Furthermore, when protruding ration was 0.082, the temperature was strongly affected by inclined angle. whereas, when protruding ration was 0.25, the temperature was strongly affected by heat source configuration.

• Fashion & Textile Research Journal
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• v.3 no.4
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• pp.351-356
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• 2001

The purpose of these experiments is to improve the perm techniques which are fast growing and changing in our life style, for customer satisfaction and to use as basic data for academic purpose through comparing between two methods which are the new permanent wave treatment and the old one. I classified the hair samples to three kinds, which are healthy, normal, and damaged hair. This study is focused on the top part of hair sample which is damaged by strong and long-time sunshine. To get the best result, I use the scanning electron microscope (JSM-5200) as main device of these experiments. The followings are the results of these experiments. First, the new way of permanent wave technique has much more damage on hair than the old one. Second, There are big differences of damaging in this study. The harmed hair has worse result than the healthier hair.

• Journal of Technologic Dentistry
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• v.16 no.1
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• pp.105-113
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• 1994

This study attempted to find out how much stress Dental Technicians of working in Dental Laboratory have built up in the midst of their daily lives are according to their sex, age, duration of work and their kinds of positions. After self-administered questionnaire were distributed by direct to 230 technicians samplely selected from dental laboratories in Seoul and Pusan of whom 163 technicians responded from october 1 through october 13, 1994. Analysis of the data was processed by t-test, $X^2$-test, ANOVA. This results are as follows. 1. Levels of Stress of the total 163 respondents by sex is not higher among male than female(p>.05). 2. Levels of stress - 36.2%(74 Dental technicians) of all Dental technicians were in stress on the whole and 9.2%(15 Dental technicians) of them were in a serious situation by accumulated stress. 3. Realization of stress - 10.1%(16 Dental technicians) of the dental technicians and 89.9%(143 Dental technicians) were found out to be in a dangerous sign or in a situation by accumulated stress. Further studies which a big size and a delicate method of measuring their general characteristics are needed.

• Cross-Cultural Studies
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• v.19
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• pp.25-38
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• 2010

The "Name" is not only representative of a person but also a cultural heritage containing national cultures. Therefore, we can easily find some cultural value from the square inch sized seal texts. This article is a comprehensive study of the characteristics of names appeared on the seals in the Warring States Period. In the Warring States Period, single name is generally used for naming and this style can be divided into 13 categories. Except unavoidable cases, such as using the name of place, the name of person or the reason of physical characteristics, using double name is very rare and this style can be categorized by 8 kinds. In result, using double name is defined as a fringe method of naming in the Warring States Period. In addition, we can find a big difference between the names of Warring States Period and those of Post-Qin and Han Dynasties in the structural aspects. In conclusion, understanding of the characteristics of names from the Warring States Period can be a great help to better understanding of ancient books and unearthed documents.

• Bulletin of the Korean Mathematical Society
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• v.56 no.4
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• pp.993-1006
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• 2019

This article concerns a ring property which preserves the reversibility of elements at nonzero idempotents. A ring R shall be said to be quasi-reversible if $0{\neq}ab{\in}I(R)$ for a, $b{\in}R$ implies $ba{\in}I(R)$, where I(R) is the set of all idempotents in R. We investigate the quasi-reversibility of 2 by 2 full and upper triangular matrix rings over various kinds of reversible rings, concluding that the quasi-reversibility is a proper generalization of the reversibility. It is shown that the quasi-reversibility does not pass to polynomial rings. The structure of Abelian rings is also observed in relation with reversibility and quasi-reversibility.

• International Journal of Computer Science & Network Security
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• v.22 no.1
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• pp.276-282
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• 2022

One of the most essential foundations upon which big institutions rely in delivering cloud computing and hosting services, as well as other kinds of multiple digital services, is the security of infrastructures for digital and information services throughout the world. Distributed denial-of-service (DDoS) assaults are one of the most common types of threats to networks and data centers. Denial of service attacks of all types operates on the premise of flooding the target with a massive volume of requests and data until it reaches a size bigger than the target's energy, at which point it collapses or goes out of service. where it takes advantage of a flaw in the Transport Control Protocol's transmitting and receiving (3-way Handshake) (TCP). The current study's major focus is on an architecture that stops DDoS attacks assaults by producing code for DDoS attacks using a cloud controller and calculating Round-Tripe Time (RTT).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.471-492
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• 2017

The demand and interest in big data analytics are increasing rapidly. The concepts around big data include not only existing structured data, but also various kinds of unstructured data such as text, images, videos, and logs. Among the various types of unstructured data, text data have gained particular attention because it is the most representative method to describe and deliver information. Text analysis is generally performed in the following order: document collection, parsing and filtering, structuring, frequency analysis, and similarity analysis. The results of the analysis can be displayed through word cloud, word network, topic modeling, document classification, and semantic analysis. Notably, there is an increasing demand to identify trending topics from the rapidly increasing text data generated through various social media. Thus, research on and applications of topic modeling have been actively carried out in various fields since topic modeling is able to extract the core topics from a huge amount of unstructured text documents and provide the document groups for each different topic. In this paper, we review the major techniques and research trends of text analysis. Further, we also introduce some cases of applications that solve the problems in various fields by using topic modeling.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1458-1464
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• 1999

The whole body of three species of fishes, raw anchovy (Engraulis japonica), big eyed herring (Harengula zunasi), and northern sand lance (Ammodytes personatus) catched at the south adjacent coast of Korea, were analyzed for extractive nitrogen, free amino acids, combined amino acids, ATP and its related compounds quaternary ammonium bases, and guanidino compounds using specimens collected in May and July 1991, and the composition of these nitrogenous components were compared with each other. The contents of extractive nitrogen in anchovy, big eyed herring, and northern sand lance were 633 mg, 601 mg, and 455 mg/100 g, respectively. Thirty-one or thirty-two kinds of free amino acids were found in the extracts of the three species of fishes. Histidine, taurine, alanine, leucine, carnosine, glutamic acid, and lysine were the major free amino acids in every sample. The composition of the major extractive components such as free amino acids, combined amino acids, ATP and its related compounds, TMAO, and creatine in the extracts were similar to each other, but their contents were some different individually.

• Journal of the Korea Society of Computer and Information
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• v.26 no.5
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• pp.103-110
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• 2021

The purpose of this study is to check the trend of press articles and research trends in journal papers in the last 10 years, which dealt with the subject of 'university core competencies' with a big data analysis method. The main research methodology of this study applied the BigKinds analysis system and the semantic network analysis methodology. The results are as follows: First, the number of press articles related to university core competencies showed a keyword trend that rapidly increased in December 2014 and the second half of 2020. Related keywords were curriculum, specialization, project group, Ministry of Education, ACE, and competitiveness. Second, the semantic network value between keywords of related research papers showed 554 degree, 18,467 avg. degree, and 0.637 density. The degree of centrality of connection was analyzed in the order of university(1606), competency(1481), core(1349), and core competency(1301). Betweenness centrality was analyzed as core competencies(13.101), university students(13.101), university(13.101), and competencies(13.101). The results of this research are expected to give implications to future research and policy-making, educational program planning and operation, etc. to members of higher education institutions, experts in education policy, and educational scholars.

• Journal of the Korea Society of Computer and Information
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• v.27 no.5
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• pp.199-204
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• 2022

The purpose of this study is to broaden the understanding of the Security Services Industry Act, and also to examine the meanings of various phenomena by analyzing the media report big data rather than the researchers' perspective on the Security Services Industry Act. In the research method, this study searched for a keyword 「Security Services Industry Act」 that prescribes the security work as an important subject of crime prevention and maintenance of public order in Korea. The data was searched from 1990 to 2021 the BIG KINDS could provide. Also, for the concrete analysis during the period of data search, it was divided into settlement period(1976~2001), growth period-quantitative(2002~2012), and growth period-qualitative(2013~2021). In the results of this study, the media report perception of the Security Services Industry Act is continuously emphasizing the social roles and importance of private security according to the flow of time. The consequent marketability of private security will play great roles in the protection of people's lives and properties in the combination with various other industries in the future. However, the private security industry that provides public peace service together with the police, could be rising as an element that hinders the development of private security industry because of various social issues caused by legal regulations and illegal problems, so it would be necessary to more strengthen its responsibility and roles accordingly.