• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.8
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• pp.718-723
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• 2007

The new concept spark plug was developed to study its influence on the combustion characteristics of SI engine. It has pre-ignition chamber in the lower end of spark plug and flame hole, in which fresh mixture gas can be introduced without any fuel supply system. This spark plug was tested with a commercial SI engine. Fuel consumption rate, emission gas and MBT timing were measured in the engine dynamometer for various flame hole numbers, hole positions, hole sizes of the pre-ignition chamber of the spark plug. And average flame propagation speed was measured by using the head gasket ionization probe in single cylinder engine. The new concept spark plug induces fast bum in combustion compared with the conventional spark plug, and MBT(Minimum advance for Best Torque) timing was retarded about $3{\sim}5^{\circ}$ crank angle. The flame hole number, hole direction and volume of pre-ignition chamber were found to influence the combustion characteristics.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.43.1-43.1
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• 2010

A novel method to characterize the topology of the early-universe intergalactic medium during the epoch of cosmic reionization is presented. The 21-cm radiation background from high redshift is analyzed through calculation of the 2-dimensional (2D) genus. The radiative transfer of hydrogen-ionizing photons and ionization-rate equations are calculated in a suite of numerical simulations under various input parameters. The 2D genus is calculated from the mock 21-cm images of high-redshift universe. We construct the 2D genus curve by varying the threshold differential brightness temperature, and compare this to the 2D genus curve of the underlying density field. We find that (1) the 2D genus curve reflects the evolutionary track of cosmic reionization and (2) the 2D genus curve can discriminate between certain reionization scenarios and thus indirectly probe the properties of radiation-sources. Choosing the right beam shape of a radio antenna is found crucial for this analysis. Square Kilometer Array (SKA) is found to be a suitable apparatus for this analysis in terms of sensitivity, even though some deterioration of the data for this purpose is unavoidable under the planned size of the antenna core.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1589-1592
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• 1994

We developed the ion plating system, consisted of the Facing Target Magnetron Sputtering System and the r.f, electrode of the coil type, which was available to control the reactive and the adhesion between thin film and substrate, and studied about the discharge characteristics and the optimum condition in order to form the high quality thin film. The characteristics of discharge and plasma was measured as Double Probe and Electrostatic Retarding Grid Analyzer. The incident ion energy on the substrate was increased as the increasing r.f power, bias voltage. By the r.f electrode, the ionization rate of the sputtered particles was about 75%, and the mean incident ion energy depend on the value which was difference between the plasma potential and biased substrate potential.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.380-386
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• 2006

In this study, we had designed and fabricated the plasma focus device which can generate the light source for EUV(Extreme Ultra Violet) lithography. And we also have investigated the basic electrical characteristics of currents, voltages, resistance and inductance of this system. Voltage and current signals were measured by C-dot and B-dot probe, respectively. We applied various voltages of 1.5, 2, 2.5 and 3 kV to the anode electrode and observed voltages and current signals in accordance with various Ar pressures of 1 mTorr to 100 Torr in diode chamber. It is observed that the peak values of voltage and current signals were measured at 300 mTorr, where the inductance and impedance were also estimated to be 73 nH and $35 m{\Omega}$ respectively. The electron temperature has been shown to be 13000 K at the diode voltage of 2.5 kV and this gas pressure of 300 mTorr. It is also found that the ion density Ni and ionization rate 0 have been shown to be $N_i = 8.25{\times}10^{15}/cc$ and ${\delta}$= 77.8%, respectively by optical emission spectroscopy from assumption of local thermodynamic equilibrium(LTE) plasma.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.10a
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• pp.49-49
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• 1999

In this study, $Cl_2/BCI_3$ magnetized inductively coupled plasmas (MICP) were used to etch GaN and the effects of magnetic confinements of inductively coupled plasmas on the GaN etch characteristics were investigated as a function of $Cl_2/BCI_3$. Also, the effects of Kr addition to the magnetized $Cl_2/BCI_3$ plasmas on the GaN etch rates were investigated. The characteristics of the plasmas were estimated using a Langmuir probe and quadrupole ma~s spectrometry (QMS). Etched GaN profiles were observed using scanning electron microscopy (SEM). The small addition of $Cl_2/BCI_3$ (10-20%) in $Cl_2$ increased GaN etch rates for both with and without the magnetic confinements. The application of magnetic confinements to the $Cl_2/BCI_3$ inductively coupled plasmas (ICP) increased GaN etch rates and changed the $Cl_2/BCI_3$ gas composition of the peak GaN etch rate from 10% $BCI_3$ to 20% $BCI_3$. It also increased the etch selectivity over photoresist, while slightly reducing the selectivity over $Si0_2$. The application of the magnetic field significantly increased positive $BCI_2{\;}^+$ measured by QMS and total ion saturation current measured by the Langmuir probe. Other species such as CI, BCI, and CI+ were increased while species such as $BCl_2$ and $BCI_3$ were decreased with the application of the magnetic field. Therefore, it appears that the increase of GaN etch rate in our experiment is related to the increased dissociative ionization of $BCI_3$ by the application of the magnetic field. The addition of 10% Kr in an optimized $Cl_2/BCI_3$ condition (80% $Cl_2/$ 20% $BCI_3$) with the magnets increased the GaN etch rate about 60%. More anisotropic GaN etch profile was obtained with the application of the magnetic field and a vertical GaN etch profile could be obtained with the addition of 10% Kr in an optimized $Cl_2/BCI_3$ condition with the magnets.

• ETRI Journal
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• v.30 no.3
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• pp.383-393
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• 2008

The etching mechanism of $ZrO_2$ thin films and etch selectivity over some materials in both $BCl_3$/Ar and $BCl_3/CHF_3$/Ar plasmas are investigated using a combination of experimental and modeling methods. To obtain the data on plasma composition and fluxes of active species, global (0-dimensional) plasma models are developed with Langmuir probe diagnostics data. In $BCl_3$/Ar plasma, changes in gas mixing ratio result in non-linear changes of both densities and fluxes for Cl, $BCl_2$, and ${BCl_2}^+$. In this work, it is shown that the non-monotonic behavior of the $ZrO_2$ etch rate as a function of the $BCl_3$/Ar mixing ratio could be related to the ion-assisted etch mechanism and the ion-flux-limited etch regime. The addition of up to 33% $CHF_3$ to the $BCl_3$-rich $BCl_3$Ar plasma does not influence the $ZrO_2$ etch rate, but it non-monotonically changes the etch rates of both Si and $SiO_2$. The last effect can probably be associated with the corresponding behavior of the F atom density.

• Korean Journal of Materials Research
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• v.23 no.9
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• pp.517-524
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• 2013

The electrical and optical properties of fluorine-doped tin oxide films grown on polyethylene terephthalate film with a hardness of 3 using electron cyclotron resonance plasma with linear microwave of 2.45 GHz of high ionization energy were investigated. Fluorine-doped tin oxide films with a magnetic field of 875 Gauss and the highest resistance uniformity were obtained. In particular, the magnetic field could be controlled by varying the distribution in electron cyclotron deposition positions. The films were deposited at various gas flow rates of hydrogen and carrier gas of an organometallic source. The surface morphology, electrical resistivity, transmittance, and color in the visible range of the deposited film were examined using SEM, a four-point probe instrument, and a spectrophotometer. The electromagnetic field for electron cyclotron resonance condition was uniformly formed in at a position 16 cm from the center along the Z-axis. The plasma spatial distribution of magnetic current on the roll substrate surface in the film was considerably affected by the electron cyclotron systems. The relative resistance uniformity of electrical properties was obtained in film prepared with a magnetic field in the current range of 180~200A. SEM images showing the surface morphologies of a film deposited on PET with a width of 50 cm revealed that the grains were uniformly distributed with sizes in the range of 2~7 nm. In our experimental range, the electrical resistivity of film was able to observe from $1.0{\times}10^{-2}$ to $1.0{\times}10^{-1}{\Omega}cm$ where optical transmittance at 550 nm was 87~89 %. These properties were depended on the flow rate of the gas, hydrogen and carrier gas of the organometallic source, respectively.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.620-627
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• 2004

On the foundation of a database of genome sequences and protein analyses, the ability to clone a gene based on a peptide analysis is becoming more feasible and effective for identifying a specific gene and its protein product of interest. As such, the current study conducted a protein analysis using 2-D PAGE followed by MALDI- TOF and ESI-MS to identify a highly expressed gene product of C. parasitica. A distinctive and highly expressed protein spot with a molecular size of 47.2 kDa was randomly selected and MALDI-TOF MS analysis was conducted. A homology search indicated that the protein appeared to be a fungal enolase (enol). Meanwhile, multiple alignments of fungal enolases revealed a conserved amino acid sequence, from which degenerated primers were designed. A screening of the genomic $\lambda$ library of C. parasitica, using the PCR amplicon as a probe, was conducted to obtain the full-length gene, while RT-PCR was performed for the cDNA. The E. coli-expressed eno 1 exhibited enolase enzymatic activity, indicating that the cloned gene encoded the C. parasitica enolase. Moreover, ESI-MS of two of the separated peptides resolved from the protein spot on 2-D PAGE revealed sequences identical to the deduced sequences, suggesting that the cloned gene indeed encoded the resolved protein spot. Northern blot analysis indicated a consistent accumulation of an eno1 transcript during the cultivation.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1446-1449
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• 1996

Thin films of diamond-like carbon(DLC) have been deposited using a magnetron plasma-enhanced chemical vapor deposition(PECVD) method with an rf(13.56 MHz) plasma of $C_{3}H_{8}$. From the Langmuir probe I-V characteristics, it can be observed that increasing the magnetic field yields an increase of the temperature($T_e$) and density($N_e$) of electron. At a magnetic field of 82 Gauss, the estimated values of $T_e$ and $N_e$ are approximately $1.5\;{\times}\;10^5$ K(13.5 eV) and $1.3\;{\times}\;10^{11}\;cm^{-3}$, respectively. Such a highly dense plasma can be attributed to the enhanced ionization caused by the cyclotron motion of electrons in the presence of a magnetic field. On the other hand, the negative dc self-bias voltage($-V_{sb}$) decreases with an increasing magnetic field, which is irrespective of gas pressure in the range of $1{\sim}7$ mTorr. This result is well explained by a theoretical model considering the variation of $T_e$. Deposition rates of DLC films increases with a magnetic field. This may be due to the increased mean free path of electrons in the magnetron plasma. Structures of DLC films are examined by using various techniques such as FTIR and Raman spectroscopy. Most of hydrocarbon bonds in DLC films prepared consist of $sp^3$ tetrahedral bonds. Increasing the rf power leads to an enhancement of cross-linking of carbon atoms in DLC films. At approximately 140 W, the maximum film density obtained is about 2.4 $g/cm^3$.

• Journal of The Korean Astronomical Society
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• v.47 no.2
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• pp.49-67
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• 2014

A novel method to characterize the topology of the early-universe intergalactic medium during the epoch of cosmic reionization is presented. The 21-cm radiation background from high redshift is analyzed through calculation of the 2-dimensional (2D) genus. The radiative transfer of hydrogen- ionizing photons and ionization-rate equations are calculated in a suite of numerical simulations under various input parameters. The 2D genus is calculated from the mock 21-cm images of high-redshift universe. We construct the 2D genus curve by varying the threshold differential brightness temperature, and compare this to the 2D genus curve of the underlying density field. We find that (1) the 2D genus curve reflects the evolutionary track of cosmic reionization and (2) the 2D genus curve can discriminate between certain reionization scenarios and thus indirectly probe the properties of radiation-sources. Choosing the right beam shape of a radio antenna is found crucial for this analysis. Square Kilometre Array (SKA) is found to be a suitable apparatus for this analysis in terms of sensitivity, even though some deterioration of the data for this purpose is unavoidable under the planned size of the antenna core.