• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제17권4호
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• pp.221-237
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• 2013

In this paper an asymptotic numerical method named as Initial Value Method (IVM) is suggested to solve the singularly perturbed weakly coupled system of reaction-diffusion type second order ordinary differential equations with negative shift (delay) terms. In this method, the original problem of solving the second order system of equations is reduced to solving eight first order singularly perturbed differential equations without delay and one system of difference equations. These singularly perturbed problems are solved by the second order hybrid finite difference scheme. An error estimate for this method is derived by using supremum norm and it is of almost second order. Numerical results are provided to illustrate the theoretical results.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1789-1795
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• 2007

Railroad, the structure maintenance and restoration project was increased and widely performed in concrete pavement road and airport, building at downtown area, bridge abutment, and other concrete structures. Especially, the ground reinforcement technique by quick-reaction expansible resins is the most effective countermeasures against differential settlement and undesired deformation of structure. In this paper, the unconfined compressive strength and some environmental related tests were conducted to evaluate compressive strength and environmental effect of quick-reaction expansive resins and soil mixtures. Also, three case histories of concrete structure and railroad restoration project are presented. Based on the laboratory test, the quick-reaction expansible resins and soil mixture represent the sufficient compressive strength and the leachate material is satisfied the environmental regulation limits. As a result of this study, the structure restoration technology using quick-reaction expansible resins is very effective for restoration of differential settlement and deformation, and it is environmentally sustainable technology.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제10권S_4호
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• pp.173-179
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• 2001

The chemical behavior and properties of the redox state of environmental pollutants was investigated using electrochemical methods. The purpose was to measure the variations in the redox reaction of differential pulse polarograms and cyclic voltammograms. The results observed the influences on redox potential and current of various factors including concentration, temperature, salt, and pH. These were established factors as the effect of the redox reaction. It can be clearly recognized that the electrode reaction are from reversible to irreversible processes. Also, it was mixing with reaction current controlled.

• 한국환경과학회지
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• 제11권2호
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• pp.131-137
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• 2002

The chemical behavior and properties on the redox state of environmental pollutant has been investigated by electrochemical methods. We carried out to measure the variations in the redox reaction of differential pulse polarogram and cyclic voltammogram. The results observed the influences on redox potential and current of various factors with temperature and pH. These were established factors as the effect of the redox reaction. It can be clearly recognized that the electrode reaction are from qusi-reversible to irreversible processes. Also, it was mixing with reaction current controlled. The bits-phenol A in the waste water was made to compound with cobalt ion and it take away from the separation into compound. The $Co(BPA)_2$ compound was not found to be dissociation in waste water. However, this compound is avery unstable(K=1.02) and for a while, it was to be a dissociation. Therefore, we believed that it was likely to a toxic substance.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.547-553
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• 2017

Differential Scanning Calorimetry(DSC)를 이용하여 파이로점화장치에 사용되는 세 가지 고에너지 물질의 열분석 실험을 수행하였다. DSC 실험 데이터를 이용하여 고에너지 물질의 반응속도식을 추출해내는 이론적 방법을 제안하고 반응속도식 추출을 수행하였다. DSC 실험 결과는 Friedman 등전환법으로 분석되었다. 질량분율에 따른 활성화에너지와 빈도인자를 추출해 내어 반응속도식을 완성하였다. 추출된 반응속도식은 고에너지 물질의 화학반응과정을 몇 단계의 주요단계로 가정하는 형태가 아닌 전체 화학 반응 과정을 나타내는 형태를 갖는다. 이는 기존의 열분석 실험을 통해 추출되는 화학반응속도식 형태에 비해 이론적 측면과 정확성 측면에서 상당한 장점을 갖는다. 도출된 반응속도식을 이용하여 실제 추진기관에 운용되는 세 가지 고에너지 물질의 성능변화를 20년에 대하여 예측하였다.

• 대한수의학회지
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• 제38권1호
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• pp.101-106
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• 1998

The present study attempted to apply polymerase chain reaction (PCR) to develop a rapid differential diagnosis among Marek's disease, reticuloendotheliosis and avian leukosis. The primers chosen to detect Marek's disease virus (MDV) flank the 132bp tandem direct repeat of the MDV genome. The primers selected for reticuloendotheliosis virus (REV) and avian leukosis virus (ALV) are based on proviral long terminal repeats of spleen necrosis virus and Rous-associated virus-2 genomes, respectively. The specific PCR products of MDV, REV and ALV were observed with each primer and the reaction was not cross-reacted among the viruses. MDV-specific DNA was also amplified from the MDV-induced lymphoma (MDCC-MSB1) but not from the REV-induced tumor and ALV-induced lymphoma (LSCC-1104B1). In addition, proviral DNA of REV from REV-induced tumor and proviral DNA of ALV from ALV-induced lymphoma were also amplified by REV-specific and ALV-specific PCRs, respectively. Therefore these three PCR methods may be used to rapidly differentiate among MDV, REV and ALV-associated tumors in diagnosis.

• Composites Research
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• 제31권1호
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• pp.30-36
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• 2018

본 연구에서는 시차주사열량계(differential scanning calorimetry, DSC)를 이용하여 유리섬유로 보강된 BPA계 에폭시 프리프레그의 경화 거동을 확인하였다. 기지재로 사용된 에폭시 수지의 전체 발열량(${\Delta}H_{total}=280.3J/g$)을 측정하기 위해 승온 실험을 하였다. $110{\sim}130^{\circ}C$ 등온 조건에서 측정된 발열량을 통해 높은 온도 조건일수록 최대 전환율과 최대 반응 속도가 증가하는 것을 확인하였다. 또한, 에폭시 프리프레그의 자기 촉매 반응을 해석하기 위해 Kamal 방정식을 적용하였으며 높은 온도 조건에서 반응 속도 상수($k_1$, $k_2$)가 큰 값으로 나타났다. 이때 얻어진 반응 속도 상수를 이용해 계산한 이론 추정치와 실험치를 비교한 결과 잘 부합하는 것을 확인하였다. 반응 초기에는 두 값이 유사하나 반응이 최종 단계에서는 반응 속도가 확산에 의해 결정되는 현상으로 인해 반응 속도의 실험치가 이론 추정치보다 더 작은 반응 속도 값을 가짐을 확인하였다.

• Journal of applied mathematics & informatics
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• 제41권5호
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• pp.1085-1102
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• 2023

In this study the magneto hydrodynamic (MHD) micro polar fluid flow of a viscous incompressible fluid past a porous medium in the presence of chemical reaction is considered. This work is devoted to investigate the Soret effect and Electromagnetic radiation effect and analyze analytically. In the energy equation the applied magnetic field strength and in the concentration equation the Soret effect are incorporated. The basic PDE (partial differential equations) are reduced to ODE (ordinary differential equations) using non dimensional variables. Then the analytical solution of the dimensionless equations are found using perturbation technique. The features of the fluid flow parameters are analyzed, discussed and explained graphically. The graphical solutions are found using MATLAB R2019b. Skin friction coefficient at the wall, Couple stress coefficient at the plate and the local surface heat flux are also thoroughly examined. Overall, this study sheds light on the complex interplay between physical parameters in the behavior of MHD micro-polar fluid past a porous medium in the presence of chemical reaction.

• Structural Engineering and Mechanics
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• 제28권2호
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• pp.221-238
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• 2008

Numerical solution to buckling analysis of beams and columns are obtained by the method of differential quadrature (DQ) and harmonic differential quadrature (HDQ) for various support conditions considering the variation of flexural rigidity. The solution technique is applied to find the buckling load of fully or partially embedded columns such as piles. A simple semi- inverse method of DQ or HDQ is proposed for determining the flexural rigidities at various sections of non-prismatic column ( pile) partially and fully embedded given the buckling load, buckled shape and sub-grade reaction of the soil. The obtained results are compared with the existing solutions available from other numerical methods and analytical results. In addition, this paper also uses a recently developed technique, known as the differential transformation (DT) to determine the critical buckling load of fully or partially supported heavy prismatic piles as well as fully supported non-prismatic piles. In solving the problem, governing differential equation is converted to algebraic equations using differential transformation methods (DT) which must be solved together with applied boundary conditions. The symbolic programming package, Mathematica is ideally suitable to solve such recursive equations by considering fairly large number of terms.

• Elastomers and Composites
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• 제38권4호
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• pp.326-333
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• 2003

Dynamic DSC 방법을 이용하여 isoprene(IR) 및 chloroprene(CR) 고무로 개질된 NR/CB 고무 복합체의 가황반응을 연구하였다. 각각의 샘플에 대하여 승온속도를 달리한 열분석 곡선을 얻었고 이로부터 Kissinger의 해석 방법에 따라 가교반응 기구를 연구하였다. 실험에 사용된 고무 복합재료는 대개 $120{\sim}180^{\circ}C$ 사이의 온도영역에서 가교 반응이 일어나는 것이 확인되었으며, 승온속도가 $3^{\circ}C/min$에서 $30^{\circ}C/min$로 빨라질수록 최대반응 속도점의 온도($T_p$)는 점점 높은 쪽으로 이동하였고, 반응 발열량도 상대적으로 커지는 것으로 관찰되었다. Kissinger의 해석방법을 이용하여 실험 데이터를 분석한 결과, 실험에 사용된 샘플의 가교반응은 1차반응에 의해 진행되는 것으로 밝혀졌으며 개질제로서 사용된 고무 중에서 IR을 사용한 경우보다는 CR을 개질제로 사용한 경우에 반응온도에 상대적으로 더 민감한 것으로 판명되었다. 그러나 충전제로 사용된 카본블랙의 경우에는 종류와는 무관하게 반응기구에는 거의 영향을 미치지 않는 것으로 밝혀졌다.