• 대한화학회지
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• 제62권5호
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• pp.352-357
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• 2018

Celecoxib (4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide) is a cyclooxygenase-2 inhibitor used in the treatment of arthritis, acute pain, and dysmenorrhoea. Celecoxib is a Biopharmaceutics Classification System (BCS) class II compound whose oral bioavailability is highly limited owing to its poor aqueous solubility. Several polymorphs of celecoxib have been identified as Form I, Form II, and Form III with melting points of about $162.8^{\circ}C$, $161.5^{\circ}C$, and $160.8^{\circ}C$, respectively. Form IV was generated from the precipitated suspension in the presence of HPMC (Hydroxypropyl methylcellulose) and Polysorbate 80. A rapid rate of dissolution is useful because the rate of dissolution of a drug typically increases its bioavailability. The aim of this study was to investigate the possibility of production of new crystal form of celecoxib that has higher solubility than Form III. New crystal form of celecoxib (Form A) has been isolated by recrystallization and characterized by differential scanning calorimetry (DSC), thermogravimetric (TG) analysis and powder X-ray diffractometry (PXRD). Form A was dissolved faster than Form III. At 30 minutes, the dissolution of Form A was 97.3%, whereas the dissolution of Form III was 82.2% (p < 0.1). After storage of three months at $20^{\circ}C$, in 24% RH (Relative Humidity), the crystal form was not transformed.

• Computers and Concrete
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• 제18권6호
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• pp.1113-1134
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• 2016

A methodology using neural networks has been proposed for rapid prediction of inelastic bending moments in reinforced concrete continuous beams subjected to service load. The closed form expressions obtained from the trained neural networks take into account cracking in concrete at in-span and at near the internal supports and tension stiffening effect. The expressions predict the inelastic moments (considering the concrete cracking) from the elastic moments (neglecting the concrete cracking) at supports. Three separate neural networks are trained since these have been postulated to represent all the beams having any number of spans. The training, validating, and testing data sets for the neural networks are generated using an analytical-numerical procedure of analysis. The proposed expressions are verified for example beams of different number of spans and cross-section properties and the errors are found to be small. The proposed expressions, at minimal input data and computation effort, yield results that are close to FEM results. The expressions can be used in preliminary every day design as they enable a rapid prediction of inelastic moments and require a computational effort that is a fraction of that required for the available methods in literature.

• 한국정밀공학회지
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• 제24권6호
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• pp.131-137
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• 2007

In metal casting process, it is very difficult to predict the form accuracy of cast part and reduce repeatability error. In this study, the variations of form accuracy were measured in the process of metal cast prototyping, where RP part is manufactured from CAD model in the first, and then, wax part is cast in the vacuum environment using the RP part as master model, and finally metal prototype is cast using ceramic mold and the wax part as pattern. To investigate the variations of form accuracy, the averages and standard deviations of error distribution of the parts measured by 3D scanner were compared. It was observed that the biggest shrinkage is generated during the extraction of wax part in the second step and the biggest deterioration of form accuracy is generated during the metal part casting in the last step.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.293-297
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• 2004

This paper is described manufacturing to jewelry by using rapid prototype. At that time, the SLC file is useful for solved generating errors to part build file. Then. we have reduced the time of manufacturing complicated three-dimensional form. Generally, it is used the STL file for rapid prototype that it is necessary to considerable time when complicated firm as jewelry generated pan build file. But the SLC file is solved to problem because it consists of configuration of a section. Neter the less, Generating Part build file hate had a lot of problem when the SLC file is used.

• Computers and Concrete
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• 제19권3호
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• pp.293-303
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• 2017

Maximum deflection in a beam is a serviceability design criterion and occurs generally at or close to the mid-span. This paper presents a methodology using neural networks for rapid prediction of mid-span deflections in reinforced concrete beams subjected to service load. The closed form expressions are further obtained from the trained neural networks. The closed form expressions take into account cracking in concrete at in-span and at near the interior supports and tension stiffening effect. The expressions predict the inelastic deflections (incorporating the concrete cracking) from the elastic moments and the elastic deflections (neglecting the concrete cracking). Five separate neural networks are trained since these have been postulated to represent all beams having any number of spans. The training, validating, and testing data sets for the neural networks are generated using an analytical-numerical procedure of analysis. The proposed expressions have been verified by comparison with the experimental results reported elsewhere and also by comparison with the finite element method (FEM). The proposed expressions, at minimal input data and minimal computation effort, yield results that are close to FEM results. The expressions can be used in every day design since the errors are found to be small.

• Bulletin of the Korean Chemical Society
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• 제18권9호
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• pp.961-965
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• 1997

1H NMR spectra of 3,3-dimethylpiperidine (1) at -70 to 30 ℃ exhibit gradual change from slow to rapid exchange between two alternate chair forms. The exchange rate constant was determined as a function of temperature by simulating the line shape of the signal from the two methyl groups using the modified Bloch equations. The resulting free energy of activation is ΔG* = 44.4±1.9 kJ mol-1 at 298 K. The 1H NMR spectrum of a D2O or dimethylsulfoxide-d6 (DMSO-d6) solution containing 1 and [SiW11CoⅡO39]6- exhibits separate signals for the free ligand and the complex, indicating that the ligand exchange is slow on the NMR time scale. In D2O the piperidine ring is frozen as a chair form even at room temperature with the cobalt ion bonded to the axial position of the nitrogen atom. When DMSO-d6 is added to the D2O solution, the NMR spectral change suggests that a rapid exchange occurs between the chair form and another conformer. It is proposed that the conformation of ^b1^b coordinated to [SiW11CoⅡO39]6- in DMSO-d6 is close to a twist form.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.119-119
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• 2000

In this research an induction motor vector control system was developed using Simulink and RTW(Real Time Workshop). On the Simulink window, control system is designed in the form of block diagrams, program codes are produced automatically with the RTW, then c compiler compiles the program codes. With this automatic real time program producing mechanism rapid prototyping is realized without the time-consuming manual program coding procedures. To show effectiveness of the proposed designing scheme a DSP-based induction motor vector control system was constructed and implemented

• 약학회지
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• 제37권1호
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• pp.95-99
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• 1993

Peroxidase activity of cytochrome P-450 was examined using N, N-dimethylaniline (NDA) as a substrate and cumene hydroperoxide (CHP) as an oxidant. The initial rates of the N-demethylation for varied concentrations of NDA (0.05-0.5 mM) by P-450 at different fixed concentrations of CHP (0.02-0.2 mM) were determined. The results suggest that P-450 proceeds its peroxidative reaction by the rapid equilibrium random bi bi mechanism to form a ternary complex with substrate and oxidant as an active intermediate.

• 한국주조공학회지
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• 제20권5호
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• pp.330-335
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• 2000

Functional metal prototypes are often required in numerous industrial applications. These components are typically needed in the early stage of a project to determine form, fit and function. Recent R/P(Rapid Prototyping) part are made of soft materials such as plastics, wax, paper, these master models cannot be employed durable test in real harsh working environment. Parts by direct metal rapid tooling method, such as laser sintering, by now are hard to get net shape, pores of the green parts of powder casting method must be infiltrated to get proper strength as tool, and new type of 3D direct tooling system combining fabrication welding arc and cutting process is reported. But a system which can build directly 3D parts of high performance functional material as metal park would get long period of system development, massive investment and other serious obstacles, such as patent. In this paper, through the rapid tooling process as silicon rubber molding using R/P master model, and fabricate wax pattern in that silicon rubber mold using vacuum casting method, then we translated the wax patterns to numerous metal tool prototypes by new investment casting process combined conventional investment casting with rapid prototyping & rapid tooling process. With this wax-injection-mold-free investment casting, we developed new investment casting process of fabricating numerous functional metal prototypes from one master model, combined 3-D CAD, R/P and conventional investment casting and tried to expect net shape measuring total dimension shrinkage from R/P pare to metal part.

• 한국산학기술학회논문지
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• 제3권2호
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• pp.110-114
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• 2002

주얼리 제조 공정중 마스터패턴 제조 공정은 전체 제조원가의 20%를 차지하기 때문에 매우 중요한 공정이다. 지금까지는 수작업으로 왁스 패턴을 제작하고 이를 이용하여 석고형을 만들고 석고형으로 마스터 패턴을 제작하는 복잡한 공정을 거쳐 제작하였다. 본 연구는 쾌속조형기를 이용하여 듀라폼 재질의 몰드를 만들고 저융점합금을 이용하여 마스터패턴을 직접 제작하는 새로운 공정을 개발하였다. 듀라폰의 용융진이 190℃ 이므로 용융점 70℃의 Pb-Sn-Bi-Cd 계의 저융점 합금을 주물재료로 이용하여 마스터패턴을 제작하였다.