• Bulletin of the Korean Chemical Society
• /
• 제26권8호
• /
• pp.1177-1184
• /
• 2005

Ab initio quantum chemical molecular orbital calculations have been performed for the unimolecular decomposition of methacrylonitrile ($CH_3C(CN)=CH_2$), especially for HCN and $H_2$ molecular elimination channels. Structures and energies of the reactants, products, and relevant species along the individual reaction pathways were determined by MP2 gradient optimization and MP4 single point energy calculations. Direct four-center elimination of HCN and three-center elimination of H2 channels were identified. In addition, H or CN migration followed by HCN or H2 elimination channels via the methylcyanoethylidene intermediate was also identified. Unlike the case of crotonitrile previously studied, in which the dominant decomposition process was the direct three-center elimination of HCN, the most important reaction pathway should be the direct threecenter elimination of $H_2$ in the case of methacrylonitrile.

• 대한산업공학회지
• /
• 제29권1호
• /
• pp.78-89
• /
• 2003

Ordering is performed to reduce the amount of fill-ins of the Cholesky factor of a symmetric positive definite matrix. This paper proposes a new ordering algorithm that reduces the fill-ins of the Cholesky factor iteratively by elimination tree rotations and clique separators. Elimination tree rotations have been used mainly to reorder the rows of the permuted matrix for the efficiency of storage space management or parallel processing, etc. In the proposed algorithm, however, they are repeatedly performed to reduce the fill-ins of the Cholesky factor. In addition, we presents a simple method for finding a minimal node separator between arbitrary two nodes of a chordal graph. The proposed reordering procedure using clique separators enables us to obtain another order of rows of which the number of till-ins decreases strictly.

• 한국안전학회지
• /
• 제12권2호
• /
• pp.95-101
• /
• 1997

The confidence of new technology development for NO_x$ components elimination is obtained as conclusion based 1ike followings ; 1) The technology using PSC spark is a excellent methods for NO_x$ components elimination above 70% without by-product pollutants. 2) Some materials like Oxygen, Vaporized Water and Ammonia, increase the of NO_x$ elimination by staged addition. 3) Environmental conditions like pulse frequency and peak voltage are the important dosing factors for pollutants elimination effects. 4) As the PSC technic is the up-to-date one for pollutions elimination the research and development must be executed continuously for the purpose of theoretical establishment. And the application field must be broaden in future.

• Journal of Electrical Engineering and Technology
• /
• 제10권3호
• /
• pp.944-951
• /
• 2015

Pulse Width Modulation (PWM) techniques are increasingly employed for PWM inverter fed induction motor drive. Among various popular PWM methods used, Selective Harmonic Elimination PWM (SHEPWM) has been widely accepted for its better harmonic elimination capability. In addition, using SHEPWM, it is also possible to maintain better voltage regulation. Hence, in this paper, an attempt has been made to apply Bacterial Foraging Algorithm (BFA) for solving selective harmonic elimination problem. The problem of voltage harmonic elimination together with output voltage regulation is drafted as an optimization task and the solution is sought through proposed method. For performance comparison of BFA, the results obtained are compared with other techniques such as derivative based Newton-Raphson method, and Genetic Algorithm. From the comparison, it can be observed that BFA based approach yields better results. Further, it provides superior convergence, reduced computational burden, and guaranteed global optima. The simulation results are validated through experimental findings.

• 한국멀티미디어학회논문지
• /
• 제10권5호
• /
• pp.687-697
• /
• 2007

자바 바이트코드는 많은 장점을 가지고 있지만, 수행속도가 느리고 프로그램 분석이나 최적화에 적절한 표현이 아니라는 단점이 존재한다. 따라서 네트워크와 같은 실행 환경에서 효율적으로 수행되기 위해서는 최적화된 코드로 변환이 필요하다. 따라서 우리는 최적화된 코드로의 변환을 위해 CTOC를 구현하였다. 최적화 과정에서 CTOC는 정적으로 값과 타입을 결정하기 위해 변수를 배정에 따라 분리하는 SSA From을 사용하였다. 하지만 SSA Form변환 과정에서 ${\phi}$-함수의 추가에 의해 오히려 노드의 수가 증가되는 문제점이 발생하였다. 이를 해결하기 위해 본 논문에서는 SSA Form에서 복사 전파와 죽은 코드 제거 최적화를 수행한다. 또한 기존의 SSA Form은 표현식보다는 주로 변수에 관련된 것이라는 단점이 존재한다. 따라서 본 논문에서는 SSA Form 형태의 표현식에 대해 복사 전파와 죽은 코드 제거와 같은 최적화를 적용한 후 다시 중복된 표현식을 제거하는 과정을 추가로 수행한다.

• Bulletin of the Korean Chemical Society
• /
• 제29권9호
• /
• pp.1747-1751
• /
• 2008

Reactions of n-propyl fluoroformate in a variety of pure and binary solvents have been studied at 40.0 {^{\circ}C}. The extended (two-term) Grunwald-Winstein equation has been applied to the specific rates of solvolysis of npropyl fluoroformate. The sensitivities (l = 1.80 ${\pm}$ 0.17 and m = 0.96 ${\pm}$ 0.10) to changes in solvent nucleophilicity and solvent ionizing power and the $k_F/k_{Cl}$ values are similar to those for solvolyses of n-octyl fluoroformate over the full range of solvents, suggesting that the addition step of an addition-elimination mechanism is ratedetermining. These observations are also compared with those previously reported for the corresponding chloroformate and fluoroformate esters.

• 상하수도학회지
• /
• 제33권4호
• /
• pp.311-319
• /
• 2019

The purpose of this study was to analyze water treatment characteristics, including the efficiency of removing algae from water purification plants, by installing a demonstration facility for decontamination of algae, including natural algae remover injection equipment, in the water purification plant. Jar-test showed that the optimum injection of natural decontaminant was 20 mg/L. Of the water contaminant treatment efficiency of the intake and water purification plants, Chl-a averaged 74.0% elimination efficiency from $5.0mg/m^3$ to $1.3mg/m^3$ and the maximum treatment efficiency was 91.5% removal efficiency when the inflow concentration of Chl-a was $11.8mg/m^3$. In addition, 51.2% and 47.1% of the taste and odor indicator items, geosmin and 2-MIB, resulted from the overgrowth and decaying of algae, respectively, to identify toxic substances and odor reduction effects. In addition, elimination efficiencies of SS and Turbidity materials were higher than 70.0%. In the injection of natural algae remover, no effects such as sudden changes in water quality due to secondary reactions were found, and appropriate levels were maintained under water treatment conditions.

• Journal of Power Electronics
• /
• 제10권1호
• /
• pp.43-50
• /
• 2010

This paper proposes a new harmonic elimination PWM (HEPWM) scheme for voltage source inverters (VSI) based on the curve fittings of certain polynomials functions. The resulting equations to calculate the switching angle of the HEPWM require only the addition and multiplication processes; therefore any number of harmonics to be eliminated and the fundamental amplitude of the pole switching waveform (NP1) can be controlled on-line. An extensive angle error analysis is carried out to determine the accuracy of the algorithm in comparison to the exact solution. To verify the workability of the technique, an experimental single phase VSI is constructed. The algorithm is implemented on a VSI using a 16-bit microprocessor. The results obtained from the test rig are compared to the theoretical prediction and the results of the MATLAB simulations.

• 한국전기전자재료학회논문지
• /
• 제11권10호
• /
• pp.891-896
• /
• 1998

The relaxation and elimination characteristics of polarization-photoinduced dichroism have been investigated in amorphous chalcogenide thin films deposited having normal(0。) and obique (80。) vapor incident angles. The dark relaxation kinetics of dichroism from a saturation point(D\ulcorner\ulcorner) to a certain relaxation point(D\ulcorner\ulcorner) grew to be longer on subsequent cycles of switching on and off of the inducing light, and these decays are changed from simple exponential decay to stretched exponential decay. The dichroism induced by a long time(~3.3 hrs) exposure exhibited the characteristics of longer time maintenance and smaller decreasing rate, in contrast with that by a short time (~min) exposure. In addition, the dichroism was eliminated by the exposure of non-polarized He-Ne laser.

• 소성∙가공
• /
• 제13권7호
• /
• pp.614-622
• /
• 2004

A new approach for the automatic elimination of free edges in the finite element model for the analysis of sheet metal forming processes is presented. In general, the raw finite element model constructed from an automatic mesh generator is not well suited for the direct use in the downstream forming analysis due to the many free edges which requires tedious time consuming interactive graphic operations of the users. In the present study, a general method for the automatic elimination of free edges is proposed by introducing a CAD/CAE hybrid method. In the method a trimmed parametric surface is generated to fill the holes which are orginated from the free edges by using the one step elastic finite element analysis. In addition, mesh generation algorithm is suggested which can be used in the general trimmed surface. In order to verify the validity of the proposed method, various examples including actual automobile sheet metal parts are given and discussed.