• Journal of Advanced Marine Engineering and Technology
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• v.30 no.5
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• pp.629-635
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• 2006

Manufacture of motor by laser has been studying realization that was demands on market for lightening and miniaturization. Moreover. early in the 1980s. manufacture of parts for automobiles by laser welding was already successfully introduced. The purpose of this study was to develop production technology of the high quality laminated stator core for motor by pulsed Nd:YAG laser heat source. In the event of adjusting defocus and voltage to control humping in laser welding of the laminated core. sound bead could be obtained. but deep penetration was not. Therefore. explosive evaporating plasma was controlled by adjustment of peak power on pulse width. Particularly, because explosive evaporating plasma induced high peak power, made molten metal in keyhole scatter. a suitable adjustment of peak power was required to obtain sound bead. As a results of experiment. sound bead and deep penetration could be obtained.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.381.2-381.2
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• 2014

In this study the amorphous carbon films were deposited by PECVD at the substrate temperature range of 250 to $600^{\circ}C$, and the process conditions of higher and lower precursor flow rate, respectively. The temperature was a main parameter to control the density and mirco-structures of carbon films, and their's properties depended with the process temperatrue are changed by controlling precursor flow rate. The precursor feeding rate affect on the plasma ion density and a deposition reactivity. This change of film properties was obtained the instrinsic stress, FT-IR & Raman analysis, refractive index (RI) and ext. coef. (k) measured by ellipsometer. In the process conditions of lower and higher flow rate of precursor it had a different intrinsic stress as a function of the substrate temperature.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.879-881
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• 1999

Radical and ion densities in a CF4 plasma have been calculated as a function of input power density. 9as pressure and feed gas flow rate using simple 0 dimensional global model. Fluorine atom is found to be the most abundant neutral particle. Highly fragmented species such as CF and CF+ become dominant neutral and ionic radical at the high power condition. As the pressure increases. ion density increases but ionization rate decreases due to the decrease in electron temperature. The fractional dissociation of CF4 feed gas decreases with pressure after increasing at the low pressure range. Electron density and temperature are almost independent of flow rate within calculation conditions studied. The fractional dissociation of CF4 monotonically decreases with flow rate. which results in increase in CF3 and decrease in CF density. The calculation results show that the SiO2 etch selectivity improvement correlates to the increase in the relative density of fluorocarbon ion and neutral radicals which has high C/F ratio.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.2 s.107
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• pp.107-114
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• 2006

The present experimental study deals with noise reduction and improvements in cooling performance in a plasma display panel (PDP) television (TV). The main ideas of the fan system noise reduction are maintenance of uniform inflow condition and reduction of the system loss, ${\Delta}P.$ The discrete noise is mainly related with the inflow condition therefore removing the structure which distorts inflow makes the discrete noise reduction. The broadband noise in PDP TV is related with the system losses which result from the presence of the fan downstream obstacle, PDP rear case. Through the modification of the distance and preventing the leakage flow between the fan and rear case, we can obtain the system loss and broadband noise reduction. Additionally we can reduce fan rotating speed because of increased flow rate which obtains from the reduction of system loss (resistance). Finally, 4.2 dB(A) noise reduction and $10\%$ increase in flow rate are achieved. From these results, we show that the reduction of system loss is the most effective way of the fan system noise reduction.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.37-42
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• 1992

Abstract-The ECR(E1ectron Cyclotron Resonance) plasma etcher was developed for process of manufacturing 16M164' DRAM and applied to poly-Si etching process. The etching rate and selectivity of poly-Si were investigated by changing the process factor of pressure gas and microwave power. The increasing power of microwave will have the trend of increasing the etching rate and selectivity of Oxide, and have suitable value process pressure at 6 mTorr. The increasing value of process gas SFdSF6+ Clz will cause the decrease of etching rate and selectivity, this is because the best process factor is not found.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.395-398
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• 1999

In ac PDP(plasma Display Panel), the discharge characteristics is very important to display clear images. In this paper, we have studied the measurement of voltage transfer curves which show the discharge characteristics in AC PDP. The change of the effective wall capacitance during a discharge is also studied. These depend on lateral spreading of charge distribution and the strength of the discharge. As a parameter of the frequency, we observed the effects of the frequency in voltage transfer curves and in effective wall capacitance changes. As frequency increases, minimum sustain voltage and firing voltage decrease. In upper region of gap voltage the chance of the effective wall capacitance is independent of frequency.

• Journal of the Semiconductor & Display Technology
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• v.7 no.2
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• pp.63-67
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• 2008

The MgO protective layer plays an important role in plasma display panels (PDPs). Our previous work demonstrated that the properties of MgO thin film could be improved, which were deposited by ion beam assisted deposition (IBAD). However arc discharge always occurs during the IBAD process. To avoid this problem, oxygen neutral beam assisted deposition (NBAD) is used to deposit MgO thin films in this paper. The energy of the oxygen neutral beam was used as the parameter to control the deposition. The experimental results showed that the oxygen neutral beam energy was effective in determining in F/$F^+$ centers, crystal orientation, surface morphology of the MgO thin film, and the discharge characteristics of AC PDP. The lowest firing voltage $(V_f)$ and the highest secondary electron emission coefficient $(\gamma)$ were obtained when the neutral beam energy was 300 eV.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.498-504
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• 2012

Oxide layers were prepared by an environmentally friendly plasma electrolytic oxidation (PEO) process on an Al-1050 substrate. The electrolyte for PEO was an alkali-based solution with $Na_2SiO_3$ (8 g/L) and NaOH (3 g/L). The influence of the electrical parameters on the phase composition, microstructure and properties of the oxide layers formed by PEO were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The voltage-time responses were recorded during various PEO processes. The oxides are composed of two layers and are mainly made of ${\alpha}$-alumina, ${\gamma}$-alumina and mullite phases. The proportion of each phase depends on various electrical parameters. It was found that the surface of the oxides produced at a higher current density and Ia/Ic ratio shows a more homogeneous morphology than those produced with the electrical parameters of a lower current density and lower Ia/Ic ratio. Also, the oxide layers formed at a higher current density and higher Ia/Ic ratio show high micro-hardness levels.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.44.4-45
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• 2020

The solar chromosphere can be observed well through strong absorption lines. We infer the physical parameters of chromospheric plasmas from these lines using a multilayer spectral inversion. This is a new technique of spectral inversion. We assume that the atmosphere consists of a finite number of layers. In each layer the absorption profile is constant and the source function is allowed to vary with optical depth. Specifically, we consider a three-layer model of radiative transfer where the lowest layer is identified with the photosphere and the two upper layers are identified with the chromosphere. This three-layer model is fully specified by 13 parameters. Four parameters can be fixed to prescribed values, and one parameter can be determined from the analysis of a satellite photospheric line. The remaining eight parameters are determined from a constrained least-squares fitting. We applied the multilayer spectral inversion to the spectral data of the Hα and the Ca II 854.21 nm lines taken in a quiet region by the Fast Imaging Solar Spectrograph (FISS) of the Goode Solar Telescope (GST). We find that our model successfully fits most of the observed profiles and produces regular maps of the model parameters. We conclude that our multilayer inversion is useful to infer chromospheric plasma parameters on the Sun.

• The Korean Journal of Pharmacology
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• v.26 no.2
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• pp.209-217
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• 1990

Intramolecular excimer formation with 1,3-di(1-pyrenyl)propane (Py-3-Py) and fluorescence polarization with 1,6-diphenyl-1,3,5-hexatriene (DPH) were used to evaluate the effects of barbiturates on the bulk fluidity of the model membranes of phosphatidylethanolamine fraction of synaptosomal plasma membrane vesicles (SPMVPE) isolated from bovine cerebral cortex. In the SPMVPE, barbiturates decreased the excimer to monomer fluorescence intensity ratio (I'/I) of Py-3-Py and increased the fluorescence polarization (P), anisotropy (r), limiting anisotropy $(r_{8})$, order parameter (S) and rotational relaxation time $({\bar{P}})$ of DPH in a dose-dependent manner. The relative potencies of barbiturates to order the SPMVPE were in the order: pentobarbital > hexobarbital > amobarbital > phenobarbital. Hence, it is concluded that barbiturates have ordering effects on the SPMVPE. And the membrane-ordering potencies of barbiturates appear to be correlated with the potencies for enhancement of GABA-stimulated chloride influx and with the anesthetic effects of barbiturates.