• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.5
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• pp.60-71
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• 2007

The startup characteristic of liquid propellant rocket engine should be focused on the stable ignition of combustion chamber and gas generator. Also, to lessen the propellants consumption during this period which doesn't contribute to the flight thrust, the engine has to be transferred to the nominal mode quickly. Because of the risk of test, it is impossible to develop all the startup cyclogram or the specifications of engine by test, so the precedent numerical approach is quite necessary. In this study we developed a mathematical model for the startup phenomena in a liquid rocket engine driven by gas generator-turbopump system based on the commercial 1-D flow system analysis program, Flowmaster. Using this program we proposed a methodology to obtain the specifications of turbine starter and the opening time of shutoff valves for the stable startup of the engine. To verify this methodology we qualitatively compared the analysis results to the typical startup curve of the published engine, then found it is quite well matched.

• Journal of Plant Biology
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• v.36 no.2
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• pp.127-132
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• 1993

Self-incompatibility in Brassica campestris is controlled by multi-allele system in a single genetic locus, the S locus, and it is elucidated that S-glycoproteins are S gene products. In this experiments, we examined the genetic mode(pollen tube behavior and segregation of S-glycoprotein), characteristic of S-glycoproteins and DNA constitution within nuclear genome on S gene family that unexplained by single locus model, and investigated the segregation pattern of S-glycoproteins in bred F1 generation. By diallel cross among the 15 plants within one family the existence of three types of homozygotes and three types of heterozygotes were observed, and segregation of S-allele could not explained by single locus model. From the results of IEF-immunoblot analysis for non-segregated individual plant, the segregation pattern of S specific bands was corresponded with results of diallel cross except with one case(SaSa genotype). The molecular weight of 6 different S-genotype varied in near by 50 kD, and each genotype expressed with 2 or 3 bands. Specific bands in SaSa, SbSb, ScSc has almost similar molecular weight between them. Southern analysis of genomic DNA probed with S-glycoprotein cDNA for 6 different genotypes revealed that there are clear difference in polymorphism, multiple bands of hybridization, when restriction enzymes of EcoR I were used. It could be assumed that there are several sequences related to the S-glycoprotein structural genes within their nuclear genome. Therefore, we suggested the possibilities that S-allele system could be controlled by multi-locus, that dominance-recessive interactions could be explained by modifier gene or supressor gene based on the results of abnormal segregation of S-glycoprotein in bred F1. The F2 analyses are progressing in now.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.5
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• pp.39-48
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• 2000

We newly proposed a polymer based vertical asymmetric optical coupler, which was characterized by simple fabricating procedure and short coupling length. And we fabricated a thermo-optic modulator using the polymeric optical coupler. We optimized the proposed device by coupling characteristic analysis. In a TE polarized 1.33${\mu}{\textrm}{m}$ wavelength, we obtained very short coupling length(L=277.6${\mu}{\textrm}{m}$) with 0.4${\mu}{\textrm}{m}$ thickness of middle layer, high coupling efficiency(94%), and asymmetric vertical waveguides with n$_{u}$ = 1.522, n$_{l}$ = 1.51. We implemented vortical asymmetric thermo-optic modulator with lower inverted rib waveguide and upper slab waveguide. In the 600Hz bandwidth and 4.5㎽ input power, the extinction ratio of the mode was 17㏈ with an insertion loss of 4.5㏈.

• Aerospace Engineering and Technology
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• v.1 no.2
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• pp.19-31
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• 2002

Crush energy characteristics of graphite/epoxy square tubes are experimentally studied. Effect of the ply orientation on the peak load and the average load is investigated by applying compressive load on the top of the composite square tubes under the stroke control with crosshead speed of 0.003mm/sec and 0.3mm/sec. in addition to the experimental survey, the finite element analysis is used to estimate the peak load of the composite square tubes with [0/90]₄ and [0/±45/90]₂. The first buckling mode of the tube is superimposed to the perfect geometry and the distributed compressive load is applied on the top of the tubes. The applied compressive load that make Tsai-Wu criteria equal to one is regarded as the peak load of the tubes. The experimental data shows that the square tube with [45/-45]₄ has the highest peak load and the square tube with [60/-60]₄ has the average sustained load. The measure peak load of the composite tubes with [0/90]₄ and [0/±45/90]₂agree well with the estimated peak load using the finite element analysis.

• The Research Journal of the Costume Culture
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• v.20 no.3
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• pp.347-362
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• 2012

Formatively and artistically aspect, a hybrid can be said to be a phenomenon in which two mutually different genres are combined. Make-up is thought to be very important to arrange the foundation available for predicting and pursuing a flow and direction of future hybrid make-up based on this, by analyzing a flow centering on hybrid trend, which was shown previously. In terms of objectives of this study, the first, aim is to suggest a model for researching make-up by grasping the developmental process and the characteristics of hybrid art through considering an art theory of hybridity, shown in make-up. The second, aim is to design make-up by analyzing trends in make-up style after deconstructing the hybrid genre. The modern make-up design through genre-deconstruction characteristics beyond diverse plurality and genre could be known to be highlighted as aesthetic characteristic by a slight attempt as communication of open space, which connects culture and genre, which had failed to be recognized and was neglected. Empirical research has, produced a work by systematically arranging make-up design. This study, identifies two kind of barrier demolition, such as the class deconstruction and the temporal, spatial disorder centering on genre deconstruction of hybrid. There are infinite possibilities in developing make-up design in line with modern sensation through aesthetic element and symbolic significance through genre deconstruction. It was the expression mode in future make-up, to providing basic data, and to strengthening competitive edge of culture and art.

• Macromolecular Research
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• v.12 no.3
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• pp.322-324
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• 2004

Poly(1-dodecyl-2,5-pyrrylene vinylene) (PDPV) has an extended 1t-conjugated structure and exhibits characteristic spectroscopic features. The PDPV we prepared has an absorption maximum at 510nm and its long absorption tail at ca. 750nm in methylene chloride is due to the long 1t-conjugated system connected to vinyl group. The large red-shift of emission was 625nm upon excitation at 480nm, which suggests the existence of a low emissive state. The emission of PDPV in less-polar solvents decreased markedly relative to that in the more-polar solvents; this observation was ascribed possibly to quenching by a strong vibrational mode of the dodecyl groups of PDPV in less-polar solvents. Furthermore, the emission from the high-energy side had a single decay component (0.1㎱, 49.96%), while that from the low-energy side had two components (0.6㎱, 27.1 %; 2.7㎱, 22.87%). We characterized the redox properties of PDPV by cyclic voltammetry. Every redox peak showed irreversible behavior; the oxidation peaks appeared at 1.7,0.8, and 0.6V and the reduction peak at -0.5V.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3A
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• pp.171-178
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• 2003

In this paper, We has proposed two DGS(Defected Ground Structure) resonators and designed the low-pass filter using the proposed DGS types. This structure consists of two rectangular slots, a ‘II type’ slot on the ground plane, and the stub at the transmission line. It has strong advantages that can vary the return loss at the passband freely and also can easily tune the attenuation pole frequency at the stopband. For enhancing the poor skirt property at the cutoff frequency of the Single Stub ‘II Type’ DGS cell, we have obtained the steep slope attenuation characteristic by combining the rectangular slot on both sides of the DGS. This type of the LPF with the proposed structure can be made more smaller than the existing filters and be used to find the various applications for eliminating the hamonics and spurious mode at WLL and the 2.4 GHz ISM band systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.9
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• pp.1040-1049
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• 1992

When the model of control object is not described correctly, ambiguity is often expressed by unknown parameter, In a case that this ambiguity satisfies a certain condition of limit, if robust control method is used, even if model is not correctly discribed, control system can be composed. The characteristic of control based on the variable structure theory is that the influence by ambiguity of system eradicates high-gain feedback. Therefore in this paper, VSS indentifier is proposed. Transformation of control input producing control system in sliding mode actually reflects influence of ambiguity unknown parameter of control object. If useful information is out from transformation input by a few times of operation, proper identify mechanism is selected and this information is used, to decide the unknown parameter is possible. So more effective controller was composed by addition of the proposed identifier to the unknown parameter identifier of robot manipulator.

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.135-140
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• 2015

Decomposition of carbon dioxide is studied using $Ar/CO_2$ mixture inductively coupled plasmas (ICP). Argon gas was added to generate plasma which has high electron density. To measure decomposition rate of $CO_2$, optical emission actinometry is used. Changing input power, pressure and mixture ratio, the plasma parameters and the spectrum intensity were measured using single Langmuir probe and spectroscope. The source characteristic of Carbon dioxide ICP observed from the obtained plasma parameters. The decomposition rate is evolved depending on the reaction and discharge mode. This result is analyzed with both the measurement of the plasma parameters and the dissociation mechanism of $CO_2$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.8
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• pp.52-58
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• 2008

Ths paper describes the Dual-band switch which was proposed new structure that could improved the specification of broadband and designed by the optimized structure through simulation. The Dual-band switch with 2.4[GHz]/5.8[GHz] that can apply to 802.11a/b/g system that is commercialized present was studied to get a new structure with higher power, high isolation. The transmitter of switch was designed to operate a parallel switching element with stack structure of two FET. The receiver designed to have asymmetry structure that insert series FET in addition to basic serial/parallel FET. SPDT(Single Pole Double Throw) Tx/Rx FET switch is a device that can do switching from a port of input to two port of output. The fabricated SPDT switch has the characteristic of insertion loss of a below -3[dB] form DC to 6[GHz] and the isolation of a below -30D[dB](Rx mode).