• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1834-1838
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• 2012

A facile route for the synthesis of dimethyl glutarate (DMG) from cyclobutanone and dimethyl carbonate (DMC) in the presence of solid base catalysts has been developed. It was found that the intermediate carbomethoxycyclobutanone (CMCB) was produced from cyclobutanone with DMC in the first step, and then CMCB was further converted to DMG by reacting with a methoxide group. The role of the basic catalysts can be mainly ascribed to the activation of cyclobutanone $via$ the abstraction of a proton in the ${\alpha}$-position by base sites, and solid bases with moderate strength, such as MgO, favor the formation of DMG.

• 펄프종이기술
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• 제39권2호
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• pp.17-24
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• 2007

PEA(Print Evenness Analyzer) Module can be utilized as a tool to evaluate print mottle. The tester is de-signed to measure the uniformity of liquid penetration into paper at very short contact time. To evaluate effects of base paper properties on print mottle, the experiments were performed with 3 types of base pa-per whose sizing degree, roughness and porosity were varied. Coated papers were produced with high solid coating color (70%) and low solid coating color (67%). Uniformity of water absorption into base paper and coated paper was measured with PEA. It was found that, in order to minimize print mottle, base paper shall be produced with a high sizing degree and low roughness and the concentration of coating color shall be kept as high as possible, providing that it has proper rheology properties for coating process.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2004년도 춘계 학술발표대회 개요집
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• pp.87-89
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• 2004

Brazing is an indispensable manufacturing technology for liquid rocket engine. In this study, for LRE injector, stainless steel 316L was used of base metal and Ni based MBF-20 of insert metal. The brazing and diffusion was carried out under various conditions. There are solid phase and. residual liquid phase in the brazed joint. With increment of holding time, the amount of solid phase increased and the elements of base metal and insert metal compositionally graded. Boron diffused from insert metal came into base metal and made boride with Cr and Mo at the brazed joint of base metal and insert metal.

• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2257-2262
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• 2014

$C_{60}$ is widely investigated because of its unique structure. But its applications in solid propellant seem to be relatively neglected. $C_{60}$ has more outstanding features than carbon black which is widely used as a catalyst ingredient of solid propellant. To combine the advantages of fullerene and lead salts, another good composite in propellant catalysts, we synthesized a kind of fullerene phenylalanine lead salt (FPL) and explored its thermal performances by differential thermal analysis (DTA) and thermogravimetry analysis (TGA). The results show it undergoes four exothermic processes started from 408 K. Combined TGA and X-ray diffractometer (XRD), the decomposition mechanism of FPL was derived by TG-IR and comparing IR spectra of FPL and its residues after burned to $327^{\circ}C$, $376^{\circ}C$ and $424^{\circ}C$, respectively. Effect of FPL on the decomposition characteristic of hexogen (RDX), a type of explosive in propellant, has been investigated using DTA at different heating rate, which shows the decomposition temperatures of the explosive are all reduced by more than 20 K. The corresponding activation energy ($E_a$) is decreased by $30kJ{\cdot}mol^{-1}$. So FPL has potential application as a combustion catalyst in solid propellant.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.547-550
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• 2008

A solid rocket motor has quite complex physical condition such exothermal chemical reaction in subsonic area and supersonic ex pansion in a converging-diverging nozzle. To introduce a simulation tool for compressible flow in supersonic range as well as incompressible chemical reaction zone in a whole rocket nozzle is a essential demand. Since the flow vary subsonic to super sonic, the convergence in computation becomes very low and unstable in a whole domain of rocket motor. This paper reports the 2-D Axisymmetric and simple 3-D solid propellant combustion and flow of gases in rocket motor by using a precondi tioning, shear stress turbulence modeling, AUSM(p). To simulate the simplified combustion process, Double base solid propellant is used to calculate reaction of solid propellant.

• 한국학교수학회논문집
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• 제17권2호
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• pp.167-191
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• 2014

본 연구는 초등수학에서 '밑'의 용어집합인 '밑변'과 '밑면'에 대한 고찰에서부터 입체도형의 '밑넓이' 개념과 그것을 구하는 과정에 대한 물음에서부터 출발한다. 곧, 연구는 초등학교 6학년 수학에서 직육면체의 밑넓이를 구하라는 문제에서 출발한다. 이에 대한 일차적인 답은 초등수학에서는 밑넓이라는 용어를 사용하지 않는다는 데서 찾을 수 있다. 그러나 중학교 1학년 수학에서 밑넓이를 '한 밑면의 넓이'로 사용하고 있는데, 문제는 초등수학에서 중학교 수학으로의 이행에서 이에 대한 설명이 없다는데 있다. 또한 초등수학에서 밑면을 정의하고, 겉넓이와 옆넓이를 다루는데, 이로부터 자연스럽게 밑넓이를 구하는 문제를 생각해볼 수 있다는데 있다. 이에 본 연구는 '밑'의 용어집합에서 그 원소인 '밑변'과 '밑면'을 검토해보고, 다음으로 밑넓이에 대한 논의를 교육과정, 교과서를 비롯하여 사전적 정의와 함께 살펴보았다. 또한 입체도형 관련 설문 문항을 작성하여 예비교사와 현장교사를 대상으로 설문을 실시하여 밑면과 밑넓이에 대한 이해 정도를 비교 분석하였다. 특히 처음과 마지막 문항에 밑넓이를 구하는 문제를 제시하여, 이 사이에서 어떤 변화가 나타나는지를 비교하였다. 그 결과 초등수학과 중학교 수학 사이의 '인지적 간극'(cognitive gap)을 확인할 수 있었으며, 이를 통해 입체도형에서 밑넓이 지도를 위한 제언과 함께 이후 도형에서의 용어 지도를 위한 후속 과제를 제안하고 있다.

• 소성∙가공
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• 제21권8호
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• pp.506-511
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• 2012

Aluminum brazing normally requires a careful control of temperature due to the small interval between brazing and melting temperatures for base materials. Unsuitable processing conditions, including brazing temperature outside admissible range, gap between brazed materials or inadequate flux feeding, can lead to joining defects. In this study, A357 was used as a filler metal for the brazing of pure aluminum base materials and brazed at temperatures in the semi-solid state. Interface microstructures with base materials were observed using optical metallography(OM) and scanning electron microcopy(SEM) with energy dispersive spectroscopy(EDS), and compared to conventional aluminum brazing.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.247-250
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• 2006

기존 연구를 통해 고체추진제 연소속도 측정을 위한 초음파 측정 시스템 및 연소속도 산정 기법을 개발하였으며, 개발 시스템을 적용하여 composite 추진제의 연소속도를 측정하였다. 본 연구에서는 연소 압력 증가에 따라 연소속도가 비선형적으로 변하는 double base형 고체 추진제 인 N-5와 AA-2 고체추진제의 연소속도를 개발 시스템을 이용하여 측정하였으며, 스트랜드버너법으로 측정된 값과의 비교를 통해 측정결과의 신뢰성을 평가하였다.

• 펄프종이기술
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• 제39권4호
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• pp.29-37
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• 2007

The effects of latex particle size, basis weight of base paper and coating color concentration on the printing quality of coated paper were investigated. Coating colors were prepared with five types of latexes having different particle sizes. Coated papers were produced with high solid coating colors and with low solid coating colors in a industrial coater, respectively. In high solid coating colors, rheology modifier was used and GCC content was high. It was concluded that, in order to control binder migration and hence print mottle, latex particle sizes shall be controlled as well as formation, sizing degree and roughness of basis paper.

• Journal of Pharmaceutical Investigation
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• 제26권2호
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• pp.125-135
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• 1996

Solid lipid nanoparticles(SLN) are particulate systems for parenteral drug administration and suitable for controlled release. SLN were prepared by homogenization process. Dispersion at increased temperature (molten lipid) was performed to yield SLN loaded with lipophilic drugs. Tetracaine base, lidocaine base, prednisolone, methyltestosterone and ethinylestradiol were used as model drugs to access the loading capacity and to study the release behavior. To investigate production parameters(lipids, surfactant concentration, homogenizing rpm) in the formation of SLN, particle size was performed by laser diffraction analysis. The mean particle size of SLN with stearic acid or trilaurin was below 1 micron. By decreasing the particle size and increasing the surfactant concentration, the release rate was increased especially in the case of highly lipophilic drug loaded SLN. Methyltestosterone or ethinylestradiol loaded SLN showed a distinctly prolonged release over a few days.