• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.331-332
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• 2015

• Communications of the Korean Mathematical Society
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• v.32 no.1
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• pp.19-27
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• 2017

We define and completely describe the structure of invo-clean rings having identity. We show that these rings are clean but not (weakly) nil-clean and thus they possess independent properties than these obtained by Diesl in [7] and by Breaz-Danchev-Zhou in [2].

• Journal of the Korean Mathematical Society
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• v.55 no.5
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• pp.1143-1156
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• 2018

In this paper, we define right singular clean rings as rings in which every element can be written as a sum of a right singular element and an idempotent. Several properties of these rings are investigated. It is shown that for a ring R, being singular clean is not left-right symmetric. Also the relations between (nil) clean rings and right singular clean rings are considered. Some examples of right singular clean rings have been constructed by a given one. Finally, uniquely right singular clean rings and weakly right singular clean rings are also studied.

• Communications of the Korean Mathematical Society
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• v.35 no.2
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• pp.455-468
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• 2020

An element in a ring R with identity is called invo-clean if it is the sum of an idempotent and an involution and R is called invoclean if every element of R is invo-clean. Let C(R) be the center of a ring R and g(x) be a fixed polynomial in C(R)[x]. We introduce the new notion of g(x)-invo clean. R is called g(x)-invo if every element in R is a sum of an involution and a root of g(x). In this paper, we investigate many properties and examples of g(x)-invo clean rings. Moreover, we characterize invo-clean as g(x)-invo clean rings where g(x) = (x-a)(x-b), a, b ∈ C(R) and b - a ∈ Inv(R). Finally, some classes of g(x)-invo clean rings are discussed.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.6 no.3
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• pp.359-368
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• 1999

Background : The purpose of this study was to determine whether cleansing the perineum and urethral meatus and using midstream urine affect the rate of bacterial contamination of urine specimens, and to determine the optimum urine collection method. We studied 41 asymptomatic healthy nursing school students. Women who were menstruating were not excluded from this study. Method : The first and midstream urine samples were collected during consecutive urinationsby each woman. The first sample was not a clean-catch specimen, and the second one was a clean-catch specimen. Both specimens were studied by urinalysis and bacterial culture with standard methods. Results : 41 women met the study criteria and 39 successfully completed the study. None of the urine cultures were positive. 68.3% of the non clean-catch first urine cultures, 53.7% of the non clean-catch midstream cultures, 33.3% of the first clean-catch urine culteres and 30.8% of the midstream clean-catch urine were found to be contaminated. There was a significant difference in the bacterial contamination rates between the first and midstream urine, and the clean-catch and non clean-catch urine(p=0.035, p =0.001 respectively). On urinalysis, 7.3% of the non clean-catch first urine, 7.3% of the non clean-catch midstream urine, 2.6% of the clean-catch first urine and 2.6% of clean-catch midstream urine were found to be above grade 2. Conclusions : According to our results, the bacterial contamination rate was the lowest in midstream and clean catch urine specimens. Threrfore it is recommended that the midstream clean-catch technique is the standard practice for collecting urine specimens for bacterial culture in women.

• Communications of the Korean Mathematical Society
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• v.35 no.1
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• pp.117-124
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• 2020

In 2013, Diesl defined a nil clean ring as a ring of which all elements can be expressed as the sum of an idempotent and a nilpotent. Furthermore, in 2017, Y. Zhou, S. Sahinkaya, G. Tang studied nil clean group rings, finding both necessary condition and sufficient condition for a group ring to be a nil clean ring. We have proposed a necessary and sufficient condition for a group ring to be a uniquely nil clean ring. Additionally, we provided theorems for general nil clean group rings, and some examples of trivial-center groups of which group ring is not nil clean over any strongly nil clean rings.

• Fire Science and Engineering
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• v.18 no.4
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• pp.78-85
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• 2004

This research analyzes Clean Room accidents, and presents research Clean Room, major fire prevention standards of Clean Room (FM, IRI, and NFPA Code), various results from Fire Simulation of analysis. The results are : the smoke diffusion is very quick coupled with the Heating, Ventilating, and Air Conditioning (HVAC) systems under fire ; the possibility of getting the result and the possibility the role of the Sprinkler systems to reduce the diffusion of the smoke. We learn about the importance to stop operating Heating, Ventilating, and Air Conditioning (HVAC) systems and to operate the Sprinkler system for securing safety with fire detection. Therefore, This research will be contributing to secure safety of Clean Room.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.6
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• pp.721-728
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• 2017

In this work, an one-dimensional analysis on spontaneous combustion in a coal stockpile was conducted using a commercial software $gPROMS^{(R)}$ based on assumption suggested by Arioy and Akgun. According to them, it is assumed that there is temperature difference between the surface of coal particle and the gas surrounded around the particle, and it is also assumed that the velocity of the gas is constant and thus oxygen is fed to the stockpile with same velocity. The higher temperature zone is formed to the surface of the coal stockpile at the initial phase and it became deepen as time is taken. Finally it was found that the temperature difference between coal particle and the gas was calculated as $57^{\circ}C$ and spontaneous combustion have not been occurred during 6 months since coal was piled in the stock.

• The Pure and Applied Mathematics
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• v.25 no.2
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• pp.115-125
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• 2018

In this paper, we introduce the notion of a clean ordered Krasner hyperring and investigate some properties of it. Now, let (R, +, ${\cdot}$, ${\leq}$) be a clean ordered Krasner hyperring. The following is a natural question to ask: Is there a strongly regular relation ${\sigma}$ on R for which $R/{\sigma}$ is a clean ordered ring? Our motivation to write the present paper is reply to the above question.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1051-1052
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• 2007

In this paper, as a clean lift, a maglev(magnetic levitation) clean lift is designed and described. The maglev clean lift, which is superior to conventional lifts in vibration, noise, clean class and speed characteristics, consists of magnets, guide rails, guide rollers, magnet module frame, cage, guidance controller, sensors, etc. As design specifications, the maximum value of vibration is 0.2G, the maximum value of noise is 60dB, and the clean class is #10. The design results for the maglev clean lift are shown and discussed.