• 에너지공학
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• 제19권3호
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• pp.195-202
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• 2010

최근 국내 연간 1차 에너지 사용량의 약 30% 이상이 폐열로 손실되어지고 있다. 이러한 현실을 타개하기 위하여, 본 논문에서는 장거리 열수송시 에너지 손실을 최소화할 수 있는 신기술로 화학 열변환을 이용한 장거리 열수송 기술을 채택하여, 화학 열변환에 있어서의 최적조건 도출을 목적으로 하였다. 화학 열변환을 위한 반응에 대해서는 많은 연구와 기술개발이 이루어지고 있으며, 그 중 물질이 안정하고, 값이 저렴하며, 생성물이 가스인 메탄올 분해 합성 반응이 가장 타당한 것으로 판단되었다. 본 연구에서는 장거리 열수송 기술 개발에 필요한 메탄올 분해 합성 반응 촉매를 각각 선정하여, 열수송 시스템 구축을 위한 메탄올 분해 합성 반응의 최적화 조건 도출을 위한 실험 연구를 수행하였다. 메탄올 합성 반응에서는 온도, 압력, $H_2$/CO ratio, 공간 속도, 촉매 형태에 따른 영향을 보았고, 메탄올의 분해 반응에서는 온도, 공간속도, 촉매 형태를 변수로 하여 상압에서 영향을 분석하여 메탄올 분해 합성 반응의 최적화 조건을 제시하였다.

• Advances in materials Research
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• 제3권4호
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• pp.199-216
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• 2014

Noble metal nanoparticles (mainly Au, Ag, Pt and Pd) have received enormous attention owing to their unique and fascinating properties. In the past decades, many researchers have reported methods to control the shape and the size of these noble metal nanoparticles. They have consequently demonstrated outstanding and tunable properties and thus enabled a variety of applications such as surface plasmonics, photonics, diagnostics, sensing, energy storage and catalysis. This paper focuses on the recent advances in the solution-phase synthesis of shape- and size-controlled noble metal nanoparticles. The strategies and protocols for the synthesis of the noble metal nanoparticles are introduced with discussion of growth mechanisms and important parameters, to present the general criteria needed for producing desirable shapes and sizes. This paper reviews their remarkable properties as well as their shape- and size- dependence providing insights on the manipulation of shape and size of metal nanoparticles, necessary for appropriate applications. Finally, several applications using the shape- and size-controlled noble metal nanoparticles are highlighted.

• BMB Reports
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• 제28권5호
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• pp.464-470
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• 1995

Quinolone antibiotics are DNA gyrase inhibitors, but their bactericidal action seems to involve more than the inhibition of DNA gyrase activity. Hence, the potentially crucial factors among possible mechanisms of quinolone action; cleavable complex formation, inhibition of DNA synthesis, and induction of SOS response were investigated. These parameters were measured in an Escherichia coli strain exposed to quinolones in the logarithmic growth phase, and correlated with the bactericidal activity of quinolones. Cleavable complex formation proved to be the factor most related to bactericidal action. Inhibition of DNA synthesis was substantially correlated with bactericidal activity, but induction of SOS response was least correlated with bactericidal activity. Therefore, it was concluded that quinolones exert bactericidal action primarily through cleavable complex formation, and subsequent unknown cellular processes together with inhibition of DNA synthesis contribute to the bactericidal activity of quinolones.

• 산업공학
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• 제24권2호
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• pp.156-163
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• 2011

The radiopharmaceutical synthesis for PET (positron emission tomography) is composed of chemical reactions using automated synthetical equipment. Due to the radioactive material, the automated equipment is being frequently developed to replace human operators who conduct dangerous, repetitive and dexterous operations. As to operation, the manipulating program is commonly coded using the spread sheet while the whole actuators are mapped in every step. The process map (program) is changed according to such parameters as temperature of reactor, keeping time, mixture sequence and amount of reagent. In cases of customizing the automated synthetical equipment or developing the new radiopharmaceuticals, lots of experiments should be conducted and the programming mistake is not allowed as it can lead abnormal control of the equipment to leak the radioactive materials. The exact process map has depended on trial and error manner. Thus, this study developed the methodology to tabulate the synthetical process to convert the process map automatically while the synthetical module formation is represented by a network model. The proposed method is validated using the actual radiopharmaceutical synthetical procedure.

• 방송공학회논문지
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• 제11권4호
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• pp.507-520
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• 2006

본 논문은 다중 카메라에서 얻은 영상과 그 영상으로부터 얻은 깊이영상(depth map)을 사용하여 중간시점에서의 영상을 생성하기 위하여 OpenGL 함수를 적용하는 방법을 소개한다. 기본적으로 영상기반 렌더링 방법은 카메라로 직접 얻은 영상을 그래픽 엔진에 적용하여 결과 영상을 생성하는 것을 의미하지만 주어진 영상 및 깊이정보를 어떻게 그래픽 엔진에 적용시키고 영상을 렌더링 하는지에 관한 방법은 잘 알려져 있지 않다. 본 논문에서는 카메라 정보로 물체가 생성될 공간을 구축하고, 구축된 공간 안에 색상영상과 깊이영상 데이터로 3차원 물체를 형성하여 이를 기반으로 실시간으로 중간영상 결과를 생성하는 방법을 제안하고자 한다. 또한, 중간영상에서의 깊이영상도 추출하는 방법을 소개하도록 하겠다.

• 한국세라믹학회지
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• 제47권6호
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• pp.608-612
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• 2010

Uvarovite Garnet is green pigment prepared by using $Cr_2O_3$, CaO and $SiO_2$ which are widely used in ceramic industry. The synthesis of above pigment was carried out by mixing $K_2Cr_2O_7$, $SiO_2$ and $CaCO_3$ as formulated and then firing at $1000{\sim}1200^{\circ}C$. To investigate the optimum synthesis condition of the Uvarovite Garnet. it was prepared by using CaO to replace $CaCO_3$, $CaF_2$ and $CaCl_2$. To get green brighter color, $Al^{3+}$ was substituted for $Cr^{3+}$. They were characterized by X-ray diffraction, UV-Vis spectroscopy, Raman spectroscopy and SEM analysis. When the pigments were applied to lime glazes (6 wt%), color parameters of Uvarovite Garnet showed the $L^*$=40.99, $a^*$=-16.23 and $b^*$=17.04.

• 대한기계학회논문집A
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• 제27권12호
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• pp.1997-2003
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• 2003

Recently, there have been many researches and developments in optical disc drive by high density of track and high access speed. Therefore, the optical pick-up should guarantee highly accurate dynamic characteristics for the wide bandwidth in order to cope with this trend. These demands for optical pick-up actuator can be solved by improvements of lens-holder through the following methods. The first way is the analysis of the sensitivity matrix of design variables for vibration modes after appropriate design parameters are selected like shapes and local dimensions of a lens-holder. The second way is the optimization of design variables by calculating sequential linear programming after the problem of extending bandwidth are converted to problem of minimizing adequate objective function. In the result, modified FE model is obtained through several iterations by finite difference scheme(FDS). While results of the first way show better convergence of the target frequency, the second result shows better reduction of mass increase.

• 동굴
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• 제71호
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• pp.5-11
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• 2006

A theoretical investigation of the solid phase mechanochemical synthesis of nano sized target product on the basis of dilution of the initial powdered reagent mixture by another product of an exchange reaction is presented. On the basis of the proposed 3 mode particle size distribution in mechanically activated mixture, optimal molar ratios of the components in mixture are calculated, providing the occurrence of impact friction contacts of reagent particles and excluding aggregation of the nanosized particles of the target reaction product. Derivation of kinetic equations for mechanochemical synthesis of nanoscale particles by the final product dilution method in the systems of exchange reactions is submitted. On the basis of obtained equations the necessary times of mechanical activation for complete course of mechanochemical reactions are designed. Kinetics of solid phase mechanosynthesis of nano TlCl by dilution of initial (2NaCl+$Tl_2SO_4$) mixture with the exchange reaction product (diluent,$zNa_2SO_4$, z=z*=11.25) was studied experimentally. Some peculiar features of the reaction mechanism were found. Parameters of the kinetic curve of nano TlCl obtained experimentally were compared with those for the model reaction KBr+TlCl+zKCl=(z+1) KCl+TlBr (z=z1*=13.5), and for the first time the value of mass transfer coefficient in a mechanochemical reactor with mobile milling balls was evaluated. Dynamics of the size change was followed for nanoparticle reaction product as a function of mechanical activation time.

• 동굴
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• 제71호
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• pp.1-4
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• 2006

Chloromethylnaphthalene is a valuable compound for obtaining of the plant growing stimulator - -napthylacetic acid. Chloromethylation of naphthalene by paraformaldehyde in the presence of glacial acetic acid, phosphoric and hydrochloric acids at temperature 80 - 85C and duration - 6 hours the -chloromethylnaphthalene yield was 55-57%. Using Box-Wilson method for mathematical planning of experiment carried out optimization of its synthesis for purpose increasing -chloromethylnaphthalene yield. Preliminary, one - factor experiments were carried out for selecting independence main parameters influencing on the synthesis. A full factor experiment of 23 with extended matrix of planning was used for optimization. Aiming to increase the -chloromethylnaphthalene yield, the obtained mathematical model was used for program of sharp raising on the reply surface. The received optimal conditions for the -chloromethylnaphthalene synthesis were selected as following: molar ratio of naphthalene parapfsormaldehyde of 1 : 2 temperature - 105C duration of the reaction - 3 hours. The yield of -chloromethylnaphthalene under these optimal conditions was 75%.

• 대한전자공학회논문지TC
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• 제46권11호
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• pp.50-55
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• 2009

본 논문에서는 분포정수 회로합성을 이용하여 최적의 정전용량 흡수 능력을 갖는 분포증폭기를 설계한다. 증폭기를 구성하는 여파기의 전달함수는 저역통과 Chebyshev 근사로 합성하며, 이의 정전용량 흡수 능력은 최소 삽입손실(MIL)과 리플의 함수로 계산한다. 분포증폭기의 능동 소자는 S-퍼래미터를 이용하여 등가회로로 모델링하며, 이의 정전용량은 전달함수의 MIL과 리플을 적절히 조정함으로써 여파기 구조로 흡수한다. 이의 응용 예로써, 0.1~7.5GHz의 주파수 대역에서 약 12.5dB의 이득을 갖는 분포증폭기를 설계하며, 실험을 통하여 정전용량 흡수 능력을 고려한 분포정수 회로합성이 분포증폭기의 설계에 유용하게 이용될 수 있음을 입증한다.