• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.5
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• pp.795-799
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• 2013

This paper describes a novel hybrid surface polishing process combining non-traditional electrochemical polishing (ECP) with external artificial ultrasonic vibration. The purpose of this study is to develop an easier method for improving stainless steel surfaces. To this end, vibration electrochemical polishing (VECP), a novel ultrasonic manufacturing process, for enhancing electrochemical reaction and surface quality compared with that achieved using conventional ECP is suggested. In addition, for finding the optimized experimental conditions, the two methods are compared under various current densities. Localized roughness of the work material is measured with atomic force microscopy (AFM) and scanning electron microscopy (SEM) for obtaining detailed surface information.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.7
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• pp.910-918
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• 2012

Carbon monoxide (CO) is a primary air pollutant as an indicator of air quality released from motor vehicle combustion. A comparative study of the distributions of CO concentration with no heat source in two tunnel models open and closed at both end sides is simulated with a commercial CFD code. The tunnel models are used to investigate the CO concentration distributions at three Reynolds numbers, which are computed by the inlet velocities of 0.3, 0.6 and 1.0 m/s. For a better tunnel design, the CFD predictive approaches are available in qualitatively studying the distributions of CO concentration. In the case of the tunnel open at both end sides in sixty seconds, the total CO concentrations are approximately twenty eight percent higher than those in the closed case.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.01a
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• pp.31-34
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• 2018

We live in the digital era, and the characteristics of our customers in the digital era are constantly changing. That's why understanding business requirements and converting them to technical requirements is essential, and you have to understand the data model behind the business layout. Moreover, BI(Business Intelligence) is at the crux of revolutionizing enterprise to minimize losses and maximize profits. In this paper, we have described a leading study about the situation of desk-top BI(software product & programming language) in aspect of front-end side and the Data Lake platform based on Big Data by data modeling in aspect of back-end side to support the business intelligence.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.2
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• pp.185-196
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• 1991

The rice culture, the most representative farming in humid regions of East Asia, have been playing a decisive role in supplying finance and staple food of the nations. This situation must be formed with exchange of techniques and interests in the matter betwen China, Korea and Japan. Especially Korea was obligated to playa bridge role because of geographical conditions, thereby the situations of agriculture were repeatedly reclaimed, and recovered by changes of cultures during external aggression, and internal disturbances. Thus, it is obvious that development of rice culture and its techniques was being undaunted in Korea. Nevertheless, in history of Korea, the documents of the government on chronicles of the dynasty were plentiful, while they were very poor in countryside and rural communities, so that it is very hard to search the transition process of rice culture and its techniques. Finally, the faming books that were begun editing from the early Chosun dynasty are here divided chronically and examined, and also the interrelationships are compared and discussed here. The objectives of this study were to discuss the following questions？ How were the dryfarming techniques, introduced from the ancient China by the end of Koryo dynasty, established to fit for our situations？ What were the basis for reestablishment of the techniques with originality？ How were they continued and changed through the internal and external wars in the Chosun dynasty？ What were suggested from these continuously results by the end of the Chosun dynasty?

• Communications of the Korean Mathematical Society
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• v.20 no.4
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• pp.861-873
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• 2005

In this paper we approximate a cylindrical helix by bi-conic and bi-quadratic Bezier curves. Each approximation method is $G^1$ end-points interpolation of the helix. We present a sharp upper bound of the Hausdorff distance between the helix and each approximation curve. We also show that the error bound has the approximation order three and monotone increases as the length of the helix increases. As an illustration we give some numerical examples.

• Journal for History of Mathematics
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• v.11 no.1
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• pp.36-41
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• 1998

In the Chosun Dynasty Nam, Byung-Gil(another name is Nam, Sang-Gil alias Won-Sang; 1820-1869) made a research comparing Chinese traditional mathematics with western mathematics, which missionaries who came to China at the end of Ming Dynasty introduced. He particularly studied fundamental differences between Chinese and western methods to solve algebraic equations. He wrote an article "Moo-Ee-Hae", in which he insisted that the two methods are eventually same though they are different in the고 expressions. His article has big significance as the first mathematic paper in the history of Korean mathematics.thematics.

• Honam Mathematical Journal
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• v.30 no.4
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• pp.617-629
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• 2008

In this paper, the authors have found an equivalent condition of the endomorphism ring End(M) of a projective module M being von Neumann regular(Theorem 1.14) and found an equivalent condition of any associative ring R being von Neumann regular (Theorem 1.13).

• Journal of the Korea Furniture Society
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• v.18 no.1
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• pp.1-12
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• 2007

Korea has a dark age in terms of culture in the last 20th century. Korea had been struggling between the Great Powers of the world in the imperialism and had sacrifice to keep our own culture itself. Japanese imperialist's a invasion, culture liquidation by Japan, Independence from Japan, Korean war and Influence by US are major bitter historical affair after close of Chosun Dynasty in the process of modernization. Therefore Korea couldn't stay in the center of world cultural core parts and was degraded as cultural consumption country which was provided oversea culture by other countries. Then Korea couldn't develop our unique traditional idea and culture. In the meantime there are both extreme phenomena; one is expulsion of other cultures absolutely and the other is only following western culture unconditionally like trimming policy in the end of colony age. These discreet and unfiltered western culture had been influenced Korea culture over the wide range strongly and resulted in cultural colony situation to produce western imitation culture without philosophy and traditional spirit. Even though Korea has met opportunity in the culture, we called "Han Trend", no formation of own culture is main reason for psychological panic. Korea furniture design is one of parts of lost of tradition culture and typical parts in reproducing western imitation culture. As a result furniture industry's major reason for loss value as exporting industry compared to other industries result in most of the furniture products without our unique identity. This situation become more deepen unfortunately. This report would like to suggest the direction of design with global competition capability and cultural identity to boost Korean furniture design industry by comparing, analyzing and speculating between design of Chosun dynasty and philosophy of modernism in western.

• Journal of Preventive Medicine and Public Health
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• v.5 no.1
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• pp.43-48
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• 1972

5 bed sand filter, applying biological oxidation, was designed and studied on the treatment of water works. Never using any coagulant agent (drugs), which may cause water pollution in pre-treatment of head water, the auther attempt a high rate filtration by the microorganism (nitrofication bacteria) end plant which populate in multi layer sand beds. The result are as follows : In order to evaluate the oxygen effect on filtration, oxygen was injected in aeration tank attached to each filter tank while filtration, and $NH_3$ was tested as a representaiive ingredient. It was found out that the aeration method was more effective, with over 33% of $NH_3$ removal capacity, than the anerobic and this 5 bed filter showed double removal capacity of $NH_3$ by comparing with conventional sand bed (2 stage bed). According to the examination of two kind of head water, pre-treated with coagulant agent and activated carton, the filtration capacity was affected by the polluted condition of head water, resulting that lower value of pollution and slower velocity of filtration showed more efficiency of $NH_3$ removal. In this experiment $NH_3$ content tested in treated water had a fairly good correlation with others.

• Journal of Fisheries and Marine Sciences Education
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• v.11 no.1
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• pp.69-87
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• 1999

This study had been analysed the establishment, the closing and the actual conditions of the fisheries school according to the four times revision and promulgation of the law of education of korea which were devided by the early term (the first Chosun educational decree), the middle term (the second Chosun educational decree) and the last term (the third and fourth Chosun educational decree), and also been investigated how the fisheries education of the school had been acted to the mobocracy and the assimilation policy and together with it's back ground through this analysis. The aim of this study is to contribute to the study of the history of the fisheries school education, analysis of change of the fisheries school education according to practical application of the Chosun educational decree. The summary of the characteristic of the each term are as under. First, in the early term of the fisheries education under the first Chosun educational decree, Experts were despatched to the each province with donated money from emperor and opened seasonal the fishing training centre, a kind of social fisheries education, and trained directly fishing technic and were going to train fisheries trainees regularly under name of elementary fisheries school. Japanese imperialism attached great importance to the vocational education in order to snack economical products from colonized Korea but actually had a purpose to train low quality technician who follow blindly their colony policy of Japanese imperialism. The fisheries schools in the circle of system in early time of Japanese imperialism, Kunsan public elementary fisheries school was established in April 1915, Yosu public elementary fisheries school was established ill May 1917 and Kyungnam Tongyoung training school was established in March 1917. Secondly, After 3.1 movement, the Japanese imperialism established an appeasement policy so called cultural politics and continued assimilation policy with skilful methods. After revision of the second Chosun educational decree, the Elementary vocational school was changed as the vocational training school. The school of fisheries education in middle of Japanese imperialism trained low quality technicians to snack fisheries resources from colonized Korea. After the middle of Japanese imperialism they paid attention on training fisheries technician through fisheries school rather than training school. With high interest and crowded volunteers, Kunsan public fisheries school was promoted in 1922, Tongyoung public fisheries school was promoted in 1923, Yongampo fisheries training school established in 1922 was promoted as Yongampo public fisheries school in 1926. Thirdly, in the time of the third and fourth Chosun educational decree, the end of Japanese imperialism, they met Pacific war after Japan vs China war. During the war time they considered the vocational school as the source of supply for materials and manpower and consequently had to expanded vocational education and systematically despatched students to war field and practiced military training. In 1938, Namhae public fisheries school was established and Chungjin fisheries school was permitted. But in order to supply manpower to Pacific war, the study period of Yosu public fisheries school was shorten from 5 years to 4 year in 1943 and also that of Tongyoung public fisheries school shorten in 1944.