• Journal of Biomedical Engineering Research
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• v.38 no.6
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• pp.277-284
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• 2017

This paper presents an implantable pH measurement electrode for wireless gastroesophageal reflux measurement. Usually, gastroesophageal reflux is diagnosed by a catheter-type wire connection between the esophagus and the diagnostic device which brings many side effects such as restriction of daily living, pain, and discomfort in the nasal cavity and pharynx of patients. In order to solve these issues, researchers have been studied a wireless measurement method and a micro-sized pH electrode for human body insertion is necessary. Commercial glass packaged pH meter is formed by a sensing and a reference electrodes in a KCl solution. However, if the glass meter is inserted into the human body, there are risks of leakage of the solution, breakage of the glass package, injury of the body elements. Therefore, the solution should be solidified on the micro-sized noble metal wire which has a characteristic of biocompatible. After solidified wire fabrication, the designed meter was tested for feasibility of measurement and the result was well agreed with pH values of commercial pH meter. Potentials in pH 1 to 12 solution was measured to obtain the sensitivity of the sensor with linearity. And we have designed a simulation of gastroesophageal reflux with symptom frequency, interval, and duration time in pH 2 solution. The proposed sensor has capable to get the same potential for 24 measurements in 3 days, and it has sensed same pH values of 2 for one hour with every 10 minutes. Furthermore, the sensor was survived for 48 hours with reasonable potentials in the acid solution.

• Journal of applied mathematics & informatics
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• v.36 no.3_4
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• pp.173-179
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• 2018

In this paper, we investigate the stability of positive weak solution for the singular p-Laplacian nonlinear system $-div[{\mid}x{\mid}^{-ap}{\mid}{\nabla}u{\mid}^{p-2}{\nabla}u]+m(x){\mid}u{\mid}^{p-2}u={\lambda}{\mid}x{\mid}^{-(a+1)p+c}b(x)f(u)$ in ${\Omega}$, Bu = 0 on ${\partial}{\Omega}$, where ${\Omega}{\subset}R^n$ is a bounded domain with smooth boundary $Bu={\delta}h(x)u+(1-{\delta})\frac{{\partial}u}{{\partial}n}$ where ${\delta}{\in}[0,1]$, $h:{\partial}{\Omega}{\rightarrow}R^+$ with h = 1 when ${\delta}=1$, $0{\in}{\Omega}$, 1 < p < n, 0 ${\leq}$ a < ${\frac{n-p}{p}}$, m(x) is a weight function, the continuous function $b(x):{\Omega}{\rightarrow}R$ satisfies either b(x) > 0 or b(x) < 0 for all $x{\in}{\Omega}$, ${\lambda}$ is a positive parameter and $f:[0,{\infty}){\rightarrow}R$ is a continuous function. We provide a simple proof to establish that every positive solution is unstable under certain conditions.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.232-234
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• 1998

In this paper, we are considered various possible disturbance conditions in order to design controller, $H_{\infty}$ optimal controller is successfully designed to control in such as situations. To do this, we are determined weighting function and design parameter $\gamma$ to method of trial and error by Glover-Doyle algorithm. To compare with $H_{\infty}$-PSS and conventional-PSS which is applied in nominal system and load variations, the dynamic characteristics of $H_{\infty}$-PSS controller was verified which has a good response.

• Journal of the Korean Wood Science and Technology
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• v.25 no.3
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• pp.75-82
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• 1997

To improve the quality of coated paper, the continuous research to the coating components and development of alternative latices is required. Recently, amphoteric latex is getting a great concern due to their changable properties of surface charge through controlling pH and some methods have been tried to prepare amphoteric latices. This study was carried out to synthesize amphoteric latex using seeding polymerization method with low concentration emulsifier. Styrene was used as a main monomer in addition to acrylonitrile for a hydrophilic comonomer. acrylic acid for a anionic comonomer and N,N-dimethylaminoethyl methacrylate for a cationic comonomer. Particle size and viscosity of latex were greatly affected by addition of acrylic acid and ammonium persulfate as an initiator. Negative charge of latex in alkali condition was changed to zero to positive charge in around pH 4.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.3
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• pp.87-94
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• 1997

As the paper market becomes more and more competitive, more mills will want to switch to alkaline papermaking to take advantage of the Vowing demand. Many papermakers have tried to do this without success in the past much like the American papermakers did in the late 1970's. The Problem is that runnability Problems occur, drainage slows, Presses pick drying becomes more difficult and sheet quality suffers as a result Sheet holes and breaks occur, and runnability becomes a real operating problem. Converting to alkaline papermaking is not as simple as turning off the alum. We must be aware of the numerous factions that alum served at acid pH and provide alkaline alternatives. It is the purpose of this paper to discuss methods of deposit control via charge neutralization and system control at alkaline pH. This article explains the concept as well as the measurement and control. The resultant benefits are seen in runnability, quality and profitability for the papermaker.

• Bulletin of the Korean Mathematical Society
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• v.53 no.6
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• pp.1651-1670
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• 2016

In this paper, we investigate exponentially biharmonic maps u : (M, g) ${\rightarrow}$ (N, h) from a Riemannian manifold into a Riemannian manifold with non-positive sectional curvature. We obtain that if $\int_{M}e^{\frac{p{\mid}r(u){\mid}^2}{2}{\mid}{\tau}(u){\mid}^pdv_g$ < ${\infty}$ ($p{\geq}2$), $\int_{M}{\mid}{\tau}(u){\mid}^2dv_g$ < ${\infty}$ and $\int_{M}{\mid}d(u){\mid}^2dv_g$ < ${\infty}$, then u is harmonic. When u is an isometric immersion, we get that if $\int_{M}e^{\frac{pm^2{\mid}H{\mid}^2}{2}}{\mid}H{\mid}^qdv_g$ < ${\infty}$ for 2 ${\leq}$ p < ${\infty}$ and 0 < q ${\leq}$ p < ${\infty}$, then u is minimal. We also obtain that any weakly convex exponentially biharmonic hypersurface in space form N(c) with $c{\leq}0$ is minimal. These results give affirmative partial answer to conjecture 3 (generalized Chen's conjecture for exponentially biharmonic submanifolds).

• East Asian mathematical journal
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• v.14 no.1
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• pp.63-76
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• 1998

we consider the hp-version to solve non-constant coefficients elliptic equations $-div(a{\nabla}u)=f$ with Dirichlet boundary conditions on a bounded polygonal domain $\Omega$ in $R^2$. In [6], M. Suri obtained an optimal error-estimate for the hp-version: ${\parallel}u-u^h_p{\parallel}_{1,\Omega}{\leq}Cp^{(\sigma-1)}h^{min(p,\sigma-1)}{\parallel}u{\parallel}_{\sigma,\Omega}$. This optimal result follows under the assumption that all integrations are performed exactly. In practice, the integrals are seldom computed exactly. The numerical quadrature rule scheme is needed to compute the integrals in the variational formulation of the discrete problem. In this paper we consider a family $G_p=\{I_m\}$ of numerical quadrature rules satisfying certain properties, which can be used for calculating the integrals. Under the numerical quadrature rules we will give the variational form of our non-constant coefficients elliptic problem and derive an error estimate of ${\parallel}u-\tilde{u}^h_p{\parallel}_{1,\Omega}$.

• Bulletin of the Korean Mathematical Society
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• v.56 no.3
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• pp.649-658
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• 2019

In this paper, we prove some congruences involving the generalized Catalan numbers and harmonic numbers modulo $p^2$, one of which is $$\sum\limits_{k=1}^{p-1}k^2B_{p,k}B_{p,k-d}{\equiv}4(-1)^d\{{\frac{1}{3}}d(2d^2+1)(4pH_d-1)-p\({\frac{26}{9}}d^3+{\frac{4}{3}}d^2+{\frac{7}{9}}d+{\frac{1}{2}}\)\}\;(mod\;p^2)$$, where a prime number p > 3 and $1{\leq}d{\leq}p$.

• Korean Journal of Mathematics
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• v.6 no.1
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• pp.17-26
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• 1998

In this paper, we briefly study the condition number of stiffness matrix with $h$-version and analyze it with $p$-version of the finite element method.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.3
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• pp.104-111
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• 2000

The study war carried out to evaluate the characteristics of inorganic phosphate factions in soil mixed with paper mill sludge compost(PMSC). The experiments were conducted by an incubation test. For the incubation test, application rates of PMSC to soil were 0, 2, 8, and 16%. Water content of the samples mixed with PMSC were adjusted to 10% and 15% and incubating temperatures of the samples were kept at $4^{\circ}C$ and $30^{\circ}C$, respectively. The results can be concluded as follows; pH increased depending on the higher rates of PMSC application to the soil during the incubation tests, because calcium content was $4.9cmol_c/kg$ and contents of nutrients were high. When the application rates of PMSC were increased Saloid-P and Fe-P decreased, while Al-P and Ca-P in soil increased during the incubation tests.