• Corrosion Science and Technology
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• 제20권5호
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• pp.266-280
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• 2021

Since 2020, the International Maritime Organization (IMO) has updated regulations on the sulfur content to be less than 0.5% in exhaust gas emitted from ships. Accordingly, the exhaust gas post-treatment device for ships, which is SOx/NOx reduction technology, was introduced. However, the exhaust gas post-treatment device is suffering corrosion because of the harsh corrosive environment formed by sulfate and chlorine oxide through the desulfurization process. In this investigation, cyclic potentiodynamic polarization (CPDP) experiment for UNS S31603 and UNS N08367 was performed in a green death solution that simulates the environment of a desulfurization device. The corrosion rate of UNS S31603 at the highest temperature was about 3 times higher than that of UNS N83067. Also, electron microscope scan revealed corrosion type UNS N83067 presents intergranular corrosion tendency. On the other hand, UNS S31603 was observed as general corrosion. The α values of UNS N08367 at 30 ℃ and 60 ℃ were higher than those of UNS S31603, thus UNS N08367 is considered to have a higher local damage tendency. Whereas, since the α value of UNS S31603 at 90 ℃ is larger than that of UNS N08367, UNS S31603 is considered to have a higher local damage trend.

• 한국물환경학회지
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• 제25권3호
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• pp.459-463
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• 2009

The adsorption features of malachite green onto activated carbon have been investigated for its treatment from aqueous solution. The influential factors were examined the initial concentration of malachite green, reaction temperature, and pH. Under experimental conditions, adsorption equilibrium of malachite green was attained within 2 hr after the adsorption started. The adsorption reaction of malachite green followed the pseudo-second order rate model, and the adsorption rate constants(k2) decreased with increasing initial concentrations of malachite green. Adsorption behavior of malachite green on activated carbon was found to follow the Freundlich model well in the initial adsorbate concentration range. With increase in temperature, the adsorbed amount of malachite green at equilibrium increased, which indicate that the adsorption reaction was endothermic reaction. Thermodynamic parameters for malachite green adsorption reaction were estimated at varying temperatures, and in the pH range of 2-10, adsorption of malachite green increased.

• 한국인터넷방송통신학회논문지
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• 제10권1호
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• pp.1-5
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• 2010

최근 녹색정보기술(G-IT), 녹색유비쿼터스기술(G-UT) 산업분야의 전문화에 따른 보안 방범 유지를 위한 국가 주요기관 시설물 또는 주요 산업 시설물 등의 보안 중요성이 강조되면서, 정부관공서 기업 및 군부대내에 최첨단 기술을 접목한 보안시스템(Security System) 구축이 절실히 요구되는 실정이다. 본 논문은 경비구역내의 경보발생장치로부터 신호를 다양한 형태의 통신기술로 수신하여, TCP/IP 망을 통하여 로컬 관제 센터와 원격관제 서버로 전송하는 녹색 유비쿼터스 지능형 무인경비 다중화장비에 관한 연구이다. 본 연구를 통하여, 무인경비 시스템의 통합 솔루션(Total Solution)을 확보하여 상호 시너지 효과 (Synergy Effect)가 가능하며, 국내외 시장 확대에 크게 기여할 것이다. 녹색 유비쿼터스 환경 구축 사업(Gu-Home, Gu-City, Gu-Health 등)중에서 방범/경비 분야에 적용할 수 있으며, 녹색 유비쿼터스 비전(Gu-Vision)을 제시할 수 있는 국가경쟁력을 갖춘 기업확장에 기여할 것으로 사료된다.

• Structural Engineering and Mechanics
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• 제28권1호
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• pp.19-38
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• 2008

A general solution to the field equations of homogeneous isotropic generalized thermoelastic diffusion with two relaxation times (Green and Lindsay theory) has been obtained using the Fourier transform. Assuming the disturbances to be harmonically time.dependent, the transformed solution is obtained in the frequency domain. The application of a time harmonic concentrated and distributed loads have been considered to show the utility of the solution obtained. The transformed components of displacement, stress, temperature distribution and chemical potential distribution are inverted numerically, using a numerical inversion technique. Effect of diffusion on the resulting expressions have been depicted graphically for Green and Lindsay (G-L) and coupled (C-T) theories of thermoelasticity.

• 대한기계학회논문집A
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• 제31권9호
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• pp.967-974
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• 2007

A general form solution is considered for a piezoelectric material containing impermeable cracks subjected to a combined mechanical and in-plane electrical loading. The analysis is based upon the Hilbert problem formulation. Using this solution, typically for a central crack in transverse isotropic piezoelectric material, a closed form solution is obtained, where one concentrated mechanical and electrical load is subjected to the crack surface. This problem could be used as a Green's function to generate the solutions of other problems with the same geometry but of different loading conditions.

• 농약과학회지
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• 제16권4호
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• pp.294-301
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• 2012

일시에 수확하는 경채류 중 쪽파와 부추에 대한 살충제 bifenthrin와 chlorfenapyr의 잔류특성을 비교 조사하였다. 수확일을 기준으로 각각 1주일 간격으로 2회 살포한 후 수확당일, 수확 3일 전, 수확 7일 전, 수확 10일 전 및 수확 14일 전에 시료를 수거하여 잔류량을 조사하였다. 수확당일의 잔류량을 기초하여 작물 중 농약살포액의 부착량을 환산한 결과, 쪽파의 경우 123.0-125.5 mL/kg, 그리고 부추에서는 70.0-74 mL/kg으로 조사되어 쪽파가 부추에 비해 더 많은 살포액이 부착될 수 있는 것으로 나타났다. 각 작물에서 bifenthrin과 chlorfenapyr의 생육기간 중 농약의 분해소실 정도를 조사한 결과, 쪽파에서 bifenthrin의 분해소실곡선은 y = 1.0334 $e^{-0.0602x}$ ($R^2$= 0.8606), chlorfenapyr는 y = 2.2603 $e^{-0.0519x}$ ($R^2$= 0.9043)이었으며, 부추에서는 bifentrhin의 경우, y = 0.7693 $e^{-0.1823x}$ ($R^2$= 0.9756), chlorfenapyr는 y = 1.2940 $e^{-0.1051x}$ ($R^2$= 0.9782)으로 나타났다. 이 분해소실곡선을 이용하여 각 작물에서 두 농약의 분해반감기를 조사한 결과, bifenthrin의 경우, 쪽파에서 분해반감기는 11.51일이었으며, 부추에서는 3.80일로서 쪽파에서의 분해 반감기가 더 긴 것으로 나타났으며, chlorfenapyr의 경우에서도 쪽파 13.35일, 부추 6.59일로 쪽파에서의 분해반감기가 더 길었다. 쪽파와 부추에서 두 농약의 잔류특성이 비교되었을 때 농약살포 후 살포액의 부착량과 작물생육기간 중 농약의 분해반감기는 부추에서보다는 쪽파에서 더 많거나 긴 것으로 나타났다.

• 대한전자공학회논문지TC
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• 제41권6호
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• pp.79-86
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• 2004

정확한 closed-form 근린함수 계산방법은 공간영역 그린함수에 포함된 Sommerfeld 적분의 계산시간을 줄이기 위해 기존에 이용되어온 복소 영상법(Complex image method)과 2단계 근사화법(Two-level approach)에 비해 훨씬 적은 오차를 갖는다. 본 논문에서는 정확한 closed-form 그린함수 계산방법을 일반적인 전원을 포함하는 평판구조에 적용하는 방법을 제안하였다.

• Steel and Composite Structures
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• 제30권1호
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• pp.57-67
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• 2019

This paper deals with the static analysis of axially functionally graded rectangular plates. It is assumed that the flexural rigidity of the plate varies exponentially along one of the plate's in-plane dimensions. Both an analytical approach and a numerical method are utilized to solve the problem. The analytical solution is obtained by using the Green's function method. To employ this approach, the adjoint boundary value problem is established. Then, exact solutions for deflection of the plate for different boundary conditions are found. In another way, a finite element formulation for the problem is developed. In order to demonstrate the validity of the Authors' formulation, the results obtained via both mentioned schemes are compared with each other for functionally graded plates and with results of previously published works for homogeneous plates. The effect of plate parameters on the response of the plate is also investigated. To remind the research background, a brief review on the application of Green's function method in plates' analysis and functionally graded plates is also presented.

• Coupled systems mechanics
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• 제9권1호
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• pp.77-89
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• 2020

This study is dedicated to the dynamic elasticity problem for a semi-strip. The semi-strip is loaded by the dynamic load at the center of its short edge. The conditions of fixing are given on the lateral sides of the semi-strip. The initial problem is reduced to one-dimensional problem with the help of Laplace's and Fourier's integral transforms. The one-dimensional boundary problem is formulated as the vector boundary problem in the transform's domain. Its solution is constructed as the superposition of the general solution for the homogeneous vector equation and the partial solution for the inhomogeneous vector equation. The matrix differential calculation is used for the deriving of the general solution. The partial solution is constructed with the help of Green's matrix-function, which is searched as the bilinear expansion. The case of steady-state oscillations is considered. The problem is reduced to the solving of the singular integral equation. The orthogonalization method is applied for the calculations. The stress state of the semi-strip is investigated for the different values of the frequency.

• Ocean Systems Engineering
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• 제13권2호
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• pp.123-146
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• 2023

In this paper, Moore-Gibson-Thompson theory of thermoelasticity is considered to investigate the fundamental solution and vibration of plane wave in an isotropic photothermoelastic solid. The governing equations are made dimensionless for further investigation. The dimensionless equations are expressed in terms of elementary functions by assuming time harmonic variation of the field variables (displacement, temperature distribution and carrier density distribution). Fundamental solutions are constructed for the system of equations for steady oscillation. Also some preliminary properties of the solution are explored. In the second part, the vibration of plane waves are examined by expressing the governing equation for two dimensional case. It is found that for the non-trivial solution of the equation yield that there exist three longitudinal waves which advance with the distinct speed, and one transverse wave which is free from thermal and carrier density response. The impact of various models (i)Moore-Gibson-Thomson thermoelastic (MGTE)(2019), (ii) Lord and Shulman's (LS)(1967) , (iii) Green and Naghdi type-II(GN-II)(1993) and (iv) Green and Naghdi type-III(GN-III)(1992) on the attributes of waves i.e., phase velocity, attenuation coefficient, specific loss and penetration depth are elaborated by plotting various figures of physical quantities. Various particular cases of interest are also deduced from the present investigations. The results obtained can be used to delineate various semiconductor elements during the coupled thermal, plasma and elastic wave and also find the application in the material and engineering sciences.