• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1995년도 추계학술대회 논문집
• /
• pp.1017-1021
• /
• 1995

Geometric and thermal errors are responsible for major components of the errors of a computer numerically controlled turning center. The planar error of a CNC turning center are comprised of 11 geometric and thermal error components. The error synthesis model is formulated by homogeneous coordinate transformation method and expresses the effect of such error components on the planar error of a CNC turning center. In this paper, the sensitivity analysis of the model on the noises through sensing and the change of temperature is addressed. The sensitivity analysis show that the error systhesis model is robust on the noses and z planar error is much affected by the change of temperatures.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
• /
• pp.644-644
• /
• 2013

Graphene is a two-dimensional sp2 layer material. Despite the short history in the empirical synthesis of the graphene layers, the academic/industrial unique features have brought highly significant interest in research and development related to graphene-related materials. In particular, the electrical and optical performances have been targeted towards pre-existing microelectronicand emerging nanoelectronic applications. The graphene synthesis relies on a variety of processing factors, such as temperature, pressure, and gas ratios involving H2, CH4, and Ar, in addition to the inherent selection of copper substrates. The current work places its emphasis on the role of experimental factors in growing graphene thin films. The thermally-grown graphene layers are characterized using physical/chemical analyses, i.e., four point resistance measurements, Raman spectroscopy, and UV-Visible spectrophotometry. Ultimately, an optimization strategy is proposed in growing high-quality graphene layers well-controlled through empirical factors.

• 한국미생물생명공학회:학술대회논문집
• /
• 한국미생물생명공학회 1986년도 추계학술대회
• /
• pp.506-508
• /
• 1986

Metabolic activity of inorganic nitrogenous compounds affects not only microbial growth but also metabolite production in fermentation technology. We have worked on the enzymes participating in ammonia assimulation of some fermentation bacteria. This paper summarizes the results on glutamine synthetase and its application in practical field. Glutamine synthetase (L-glutamate:ammonia ligase, EC. 6.3.1.2) catalyzes the formation of glutamine from glutamate and ammonia at the expense of cleavage of ATP and inorganic phosphate. The enzyme plays a dual role in nitrogen metabolism in bacteria; it is a key enzyme not only in the biosynthesis of various compounds through glutamine but also in the regulation of synthesis of some enzymes involved in the metabolism of nitrogenous compounds. The detailed works with the Eschericia coli and other enterobacterial enzymes revealed that glutamine synthetase is controlled by the following complex of mechanisms: (a) feedback inhibition by end products, (b) repression and derepression of enzyme synthesis, (c) modulation of enzyme activity in response to divalent cation and (d) covalent modification of enzyme protein by adenylylation and its cascade control. Comparative studies have also been made on the enzymes from other organisms.

• 한국분말재료학회지
• /
• 제13권5호
• /
• pp.336-339
• /
• 2006

Magnetic properties of nanostructured materials are affected in complicated manner by their microstructure such as pain size (or particle size), internal strain and crystal structure. Thus, studies on the synthesis of nanostructured materials with controlled microstructure are necessary fur a significant improvement in magnetic properties. In the present work, nanostructured Fe-Co alloy powders with a grain size of 50 nm were successfully fabricated from the powder mixtures of (99.9% purity) $FeCl_2$ and $CoCl_2$ by chemical solution mixing and hydrogen reduction.

• 한국정보통신학회논문지
• /
• 제6권4호
• /
• pp.645-651
• /
• 2002

본 논문에서는 전체적으로 묘사된 얼굴의 특징을 이용하여 얼굴 영상을 합성하는 방법을 제안한다. 제안된 방법은 얼굴의 형태를 대조하는 방법을 이용하여 만든 원영상의 작은 부분 영상들을 가지고 얼굴을 재현하였으며 얼굴 영상에서 2차원적 형태와 구조를 분리함으로서 음영부분과 경계부분을 표현할 수 있었으며, 영상과 영상의 특성을 나타내는 얼굴 부분영역을 조화롭게 재배치함으로서 합성을 가능케 하였다. 실험결과 본 논문에서 제안된 방법으로 합성한 얼굴 영상은 항상 자연스러운 얼굴 영상을 나타냄으로서 제안된 방법의 실효성을 입증하였다.

• 한국고분자학회:학술대회논문집
• /
• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
• /
• pp.337-337
• /
• 2006

The synthesis of an octafunctional resorcinarene based initiator for nitroxide mediated polymerization and its ability to yield random star copolymers of styrene and methyl methacrylate is studied. The effect of the initiator conformations towards its activity and the conditions that permit the formation of well-defined star block copolymers is also investigated in detail. The characterization of the initiator and the polymers were carried out by various spectro-analytical techniques. Well-defined random copolymers were obtained with controlled molecular weight and low PDI depending on the monomer feed.

• 한국결정성장학회지
• /
• 제11권4호
• /
• pp.176-179
• /
• 2001

Iron oxide powders were prepared under high temperature (up to $175^{\circ}C$) and pressure conditions( up to 129 pasi) by precipitation from metal nitrates with aqueous potassium hydroxide. Various types of iron oxide powders were obtained at different conditions. The size and the shape of the particles can be controlled as afunction of starting solution pH. The average particles size of the synthesized iron oxide powders increased, the particle shapes of the powders became fibrous, and the crystalline phase of the powder changes from iron oxide to iron hydroxide with increasing solution pH. The effects of synthesis parameters are discussed.

• 한국세라믹학회지
• /
• 제29권9호
• /
• pp.681-688
• /
• 1992

Ultrafine Si3N4 and Si3N4+SiC mixed powders were synthesized through thermal plasma chemical vapor deposition(CVD) using a hybrid plasma, which was characterized by the supersposition of a radio-frequency plasma and arc jet. The reactant SiCl4 was injected into an arc jet and completely decomposed in a hybrid plasma, and the second reactant CH4 and/or NH3 mixed with H2 were injected into the tail flame through double stage ring slits. In the case of ultrafine Si3N4 powder synthesis, reaction efficiency increased significantly by double stage injection compared to single stage one, although crystallizing behaviors depended upon injection speed of reactive quenching gas (NH3+N2) and injection method. For the preparation of Si2N4+SiC mixed powders, N/C composition ratio could be controlled by regulating the injection speed of NH3 and/or CH4 reactant and H2 quenching gas mixtures as well as by adjusting the reaction space.

• International Journal of Advanced Culture Technology
• /
• 제4권4호
• /
• pp.30-37
• /
• 2016

In this paper, the method of controlling the clock that is inputted on the hardware from the application, and the hardware design method are to be proposed. When the hardware is synthesized to the Field Programmable Gate Array(FPGA), the input clock is fixed, and when the input clock is changed, the synthesis process must be passed again to require more time. To solve this problem, the Mixed-Mode Clock Manager(MMCM) module is mounted to control the MMCM module from the application. The controlled MMCM module controls the input clock of the module. The experiment was process the Neural Network algorithm in the x86 CPU and SIMT based processor mounted the FPGA. The results of the experiment, SIMT-based processors, the time that is processed at a frequency of 50MHz was 77ms, 100MHz was 34ms. There was no additional synthesis time due to a change of the clock frequency.

• 통합자연과학논문집
• /
• 제1권3호
• /
• pp.250-253
• /
• 2008

New issues arise as to surface characterization, quantification and interface formation. Surface and interface control of CdSe nanocrystal systems, one of the most studied and useful nanostructures. Semiconductor quantum dots (QDs) have been the subject of much interest for both fundamental reseach and technical applications in recent years, due mainly to their strong size dependent properties and excellent chemical processibility. In this dissertation, the synthesis of CdSe quantum dots were synthesized by pyrolysis of high-temperature organometallic reagents. In order to modify the size and quality of quantum dots, we controlled the growth temperature and the relative amount of precursors to be injected into the coordinating solvent. Moreover, an effective surface passivation of monodisperse nanocrystals was achieved by overcoating them with a higher-band-gap material. Synthesized CdSe quantum dots were studied to evaluate the optical, electronic and structural properties using UV-absorption, and photoluminescence measurement.