• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.11
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• pp.5179-5202
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• 2018

Transmission Control Protocol (TCP) is the most widely used protocol in the cloud data centers today. However, cloud data centers using TCP experience many issues as TCP was designed based on the assumption that it would primarily be used in Wide Area Networks (WANs). One of the major issues with TCP in the cloud data centers is the Incast issue. This issue arises because of the many-to-one communication pattern that commonly exists in the modern cloud data centers. In many-to-one communication pattern, multiple senders simultaneously send data to a single receiver. This causes packet loss at the switch buffer which results in TCP throughput collapse that leads to high Flow Completion Time (FCT). Recently, Software-Defined Networking (SDN) has been used by many researchers to mitigate the Incast issue. In this paper, a detailed survey of various SDN based solutions to the Incast issue is carried out. In this survey, various SDN based solutions are classified into four categories i.e. TCP Receive Window based solutions, Tuning TCP Parameters based solutions, Quick Recovery based solutions and Application Layer based solutions. All the solutions are critically evaluated in terms of their principles, advantages, and shortcomings. Another important feature of this survey is to compare various SDN based solutions with respect to different performance metrics e.g. maximum number of concurrent senders supported, calculation of delay at the controller etc. These performance metrics are important for deployment of any SDN based solution in modern cloud data centers. In addition, future research directions are also discussed in this survey that can be explored to design and develop better SDN based solutions to the Incast issue.

• Journal of Industrial Technology
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• v.20 no.A
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• pp.29-36
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• 2000

The shape of the polymers in the mixed alkoxide solutions of Si(OC2H5)4 and Zr(n-OC3H7)4 with various water contents (1, 2, 4, and 8 in molar ratio to alkoxide, r) and catalysts was examined by rheological measurements, and its relation with fiber drawing behavior of the solutions was described. It was found that fibers could be drawn in the viscosity range 1~100 P from the acid-catalyzed solutions with lower water contents of the molar ratio H2O/alkoxide, $r{\leq}2$. On the other hand, no fiber could be drawn from the acid-catalyzed solutions including a large amount of water($r{\geq}4$) and the base-catalyzed solutions. The relation between the intrinsic viscosity [${\eta}$] and number average molecular weight ${\bar{M}}n$, namely $[{\eta}]=K{\bar{M}}n{\alpha}$, has shown that the acid-catalyzed spinnable solution (r = 1 and 2) had linear polymers where the exponent a's were about 0.56 and 0.81, whereas non-spinnable solutions (r = 4 and 8) had three dimensional network polymers or spherical particles where the exponent a's were 0.41-0.51 and 0.35.

• Journal for History of Mathematics
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• v.25 no.3
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• pp.1-14
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• 2012

Since JiuZhang SuanShu(九章算術), the basic field of the traditional mathemtics in Eastern Asia is the field of rational numbers and hence irrational solutions of equations should be replaced by rational approximations. Thus approximate solutions of equations became a very important subject in theory of equations. We first investigate the history of approximate solutions in Chinese sources and then compare them with those in Chosun mathematics. The theory of approximate solutions in Chosun has been established in SanHakWonBon(算學原本) written by Park Yul(1621 - 1668) and JuSeoGwanGyun(籌書管見, 1718) by Cho Tae Gu(趙泰耉, 1660-1723). We show that unlike the Chinese counterpart, Park and Cho were concerned with errors of approximate solutions and tried to find better approximate solutions.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.905-908
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• 2009

In the management of groundwater in coastal areas, saltwater intrusion associated with extensive groundwater pumping, is an important problem. The groundwater optimization model is an advanced method to study the aquifer and decide the optimal pumping rates or optimal well locations. Cheng and Park gave the analytical solutions to the optimization problems basing on Strack's analytical solution. However, the analytical solutions have some limitations of the property of aquifer, boundary conditions, and so on. A simulation-optimization numerical method presented in this study can deal with non-homogenous aquifers and various complex boundary conditions. This simulation-optimization model includes the sharp interface solution which solves the same governing equation with Strack's analytical solution, therefore, the freshwater head and saltwater thickness should be in the same conditions, that can lead to the comparable results in optimal pumping rates and optimal well locations for both of the solutions. It is noticed that the analytical solutions can only be applied on the infinite domain aquifer, while it is impossible to get a numerical model with infinite domain. To compare the numerical model with the analytical solutions, calculation of the equivalent boundary flux was planted into the numerical model so that the numerical model can have the same conditions in steady state with analytical solutions.

• Korean Journal of Materials Research
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• v.16 no.2
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• pp.80-84
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• 2006

The removal efficiency of Cu and Fe contaminants on the silicon wafer surface was examined to investigate the effect of cleaning solutions on the behavior of metallic impurities. Silicon wafers were intentionally contaminated with Cu and Fe solutions by spin coating and cleaned in different types of cleaning solutions based on $NH_4OH/H_2O_2/H_2O\;(SC1),\;H_2O_2/HCl/H_2O$ (SC2), and/or HCl/$H_2O$ (m-SC2) mixtures. The concentration of metallic contaminants on the silicon wafer surface before and after cleaning was analyzed by vapor phase decomposition/inductively coupled plasma-mass spectrometry (VPD/ICP-MS). Cu ions were effectively removed both in alkali (SC1) and in acid (SC2) based solutions. When $H_2O_2$ was not added to SC2 solution like m-SC2, the removal efficiency of Cu impurities was decreased drastically. The efficiency of Cu ions in SC1 was not changed by increasing cleaning temperature. Fe ions were soluble only in acid solution like SC2 or m-SC2 solution. The removal efficiencies of Fe ions in acid solutions were enhanced by increasing cleaning temperature. It is found that the behavior of metallic contaminants as Cu and Fe from silicon surfaces in cleaning solutions could be explained in terms of Pourbaix diagram.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.369-369
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• 2003

Viscarin is a tradename given to viscosifying carrageenans manufactured by FMC BioPolymer. The suitability of Vis car ins as rheology agents in mild cleansing applications has been investigated. Rheological properties, foam volume and clarity were measured to determine the impact of including 1 % Viscarin on 10% solutions of the following surfactants: acylglutamate, cocoamidopropyl betaine, PEG-80 laurate, sodium lauryl sulphate and sodium lauryol sarcosinate. Viscosity, pseudoplasticity and thixotropy of Viscarin/surfactant solutions varied with surfactant type. In all cases, the addition of Viscarin substantially increased viscosity. For example, at a shear rate of 1 sol, all surfactant solutions had viscosities <0.1 Pa s while viscosities of Viscarin/surfactant solutions ranged from 10 to 60 Pa s. By comparison, a solution of 1 % Viscarin had a viscosity of 0.3 Pa s. Clarity of surfactant solutions decreased in all cases on the addition of Viscarin. However, it was found that by including a mild solubilizing surfactant, such as PEG 40 hydrogenated castor oil, crystal clarity could be maintained in Viscarin/surfactant solutions. Viscarin increased the foam volume of sodium lauryolsarcosinate solutions from 10 ml to 220 ml and had no impact on the foam volume of the other surfactants tested. These results were used to formulate a clear, ultra-mild foaming cleansing gel based on sodium lauryol sarcosinate and Viscarin without the need for a secondary, foam-boasting surfactant. A mild shampoo was also formulated. Both products have excellent skin-feel and are capable of suspending bubbles and solid inclusions.

• Journal of the Korea Safety Management & Science
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• v.25 no.2
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• pp.121-128
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• 2023

Construction industry is considered as one of the most high-risk industries for work-related injuries and fatalities, accounting for more than half of fatalities in Korea. Advanced countries have recognized the critical role of designers in preventing construction accidents and have established regulations on design for safety. In line with this, the Korean government have also implemented regulations that require owners and designers to review the safety of design outcomes. However, it has been observed that designers face challenges in identifying hazards and integrating design solutions at the design stage mainly due to their shortage of required knowledge and skills. This study aimed to examine design solutions that can be applied to prevent fall accidents in the construction industry, and to establish a relationship between these solutions and fatal fall accidents occurred over the past three years in Korea. This study also analyzed the relationships of four variables (construction type, cost, work type, and fall location) with design solutions. The results indicated that all four variables have significant relationships with design solutions, with fall location showing the strongest relationship. The design solutions and their relationships with fatal fall accidents identified in this study can be utilized in identifying hazard and integrating design solutions to ensure design for safety.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.15 no.4
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• pp.253-265
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• 2011

In this paper, we study the existence of mild solutions for double perturbed impulsive neutral functional evolution equations with infinite delay in Banach spaces. The existence of mild solutions to such equations is obtained by using the theory of the Hausdorff measure of noncompactness and Darbo fixed point theorem, without the compactness assumption on associated evolution system. An example is provided to illustrate the theory.

• Honam Mathematical Journal
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• v.37 no.4
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• pp.411-421
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• 2015

This paper investigates the issue of analytic travelling wave solutions for some important coupled models of fractional order. Analytic travelling wave solutions of the considered model are found by means of the Q-function method. The results give us that the Q-function method is very simple, reliable and effective for searching analytic exact solutions of complex nonlinear partial differential equations.

• Journal of the Chungcheong Mathematical Society
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• v.25 no.3
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• pp.381-391
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• 2012

In this paper, the formal linearization method is used to construct multisoliton solutions for three model of shallow water waves equations. The three models are completely integrable. The formal linearization method is an efficient method for obtaining exact multisoliton solutions of nonlinear partial differential equations. The method can be applied to nonintegrable equations as well as to integrable ones.