• 천문학회보
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• 제39권2호
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• pp.92.2-92.2
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• 2014

NGC 6822 is a dwarf irregular galaxy in the Local Group. Unlike clouds in the Large Magellanic Cloud and the Small Magellanic Cloud, molecular clouds in NGC 6822 are not influenced by the Galactic tidal force. Therefore the star forming processes are only dictated by local conditions. Hubble V is the brightest of the several bright H II region complexes in NGC 6822. The core of Hubble V, surrounded by a molecular cloud complex, contains compact clusters of bright blue stars. During the commissioning runs of the new high-resolution near-infrared spectrometer, IGRINS (Immersion GRating near-INfrared Spectrometer), we observed Hubble V and detected many emission lines from the H II regions and from the photodissociation region at the interface between the ionized gas and the molecular cloud. In this presentation, we report preliminary results of the IGRINS observations. We discuss the implications of the observed lines ratios and kinematics for our understanding of the evolution of star forming molecular clouds.

• 천문학회보
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• 제42권2호
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• pp.42.2-42.2
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• 2017

The Large Magellanic Cloud (LMC) is a unique target to study the detail structures of molecular clouds and star-forming regions, due to its proximity and face-on orientation from us. Most part of the astrophysical subjects for the LMC have been investigated, but the magnetic field is still veiling despite its role in the evolution of the interstellar medium (ISM) and in the main force to influence the star formation process. Measuring polarization of the background stars behind interstellar medium allows us to describe the existence of magnetic fields through the polarization vector map. In this presentation, I introduce the near-infrared polarimetric results for the $39^{\prime}{\times}69^{\prime}$ field of the northeastern region of the LMC and the N159/N160 star-forming complex therein. The polarimetric observations were conducted at IRSF/SIRPOL 1.4 m telescope. These results allow us to examine both the global geometry of the large-scale magnetic field in the northeastern region and the close structure of the magnetic field in the complex. Prominent patterns of polarization vectors mainly follow dust emission features in the mid-infrared bands, which imply that the large-scale magnetic fields are highly involved in the structure of the dust cloud in the LMC. In addition, local magnetic field structures in the N159/N160 star-forming complex are investigated with the comparison between polarization vectors and molecular cloud emissions, suggesting that the magnetic fields are resulted from the sequential formation history of this complex. I propose that ionizing radiation from massive stellar clusters and the expanding bubble of the ionized gas and dust in this complex probably affect the nascent magnetic field structure.

• 천문학회보
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• 제42권1호
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• pp.38.3-39
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• 2017

The N159 and N160 ionized regions in the Large Magellanic Cloud are an important extragalactic star-forming complex. The physical environments and the star formation stages are different in N159 and N160. We performed near-infrared polarimetry to those star forming regions with IRSF/SIRPOL 1.4-m telescope. Near-infrared polarization enabled us to trace the detailed structure of magnetic fields in star-forming regions. Through the polarimetric data of J, H, and Ks bands, we examined the magnetic field structures in the N159/N160 complex. In this presentation, we show complex distribution of the magnetic fields associated with dust and gas structures. We verify the local magnetic fields in each star-forming region, which appear to be related with local environments, such as interior and boundary of shell structure, star-forming HII regions, and boundaries between HII regions and dense dark clouds. We discuss the formation scenario of the N159/N160 complex suggested from the magnetic field structure.

• Journal of Advanced Marine Engineering and Technology
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• 제23권3호
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• pp.360-368
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• 1999

The paper describes spectroscopic characteristics of plasma induced in the pulsed YAG laser welding of alloys containing a large amount of volatile elements. The authors have conducted the spectroscopic analyses of laser induced Al-Mg alloys plasma in the air and argon atmosphere. In the air environment the identified spectra were atomic lines of Al, Mg, Cr, Mn, Cu, Fe and Zn and singly ionized Mg lines as well as the intense molecular spectra of ALO and MgO formed by chemi-cal reactions of evaporated Al and Mg atoms from the pool surface with oxygen in the air. In argon atmosphere MgO and AlO spectra vanished but AlH spectrum was detected. the hydrogen source was presumable hydrogen dissolved in the base metals water absorbed on the surface oxide layer or $H_2$ and $H_2O$ in the shielding gas. The resonant lines of Al and Mg were strongly self-absorbed in particular self-absorption of the Mg line was predominant. These results show that the laser induced plasma was made of metallic vapor with relatively low temperature and high density.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.180-180
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• 2010

The design and implementation of high rate deposition process and anti-scratch property of silicon oxide film by PECVD with UHF power were investigated according to the effect of UHF input power with HF bias. New regime of high rate deposition of SiOx films by hybrid plasma process was investigated. The dissociation of OMCTS (C8H24Si4O4) precursor was controlled by plasma processes. SiOx films were deposited on polyethylene terephthalate (PET) and polycarbonate substrate by plasma enhanced chemical vapor deposition (PECVD) using OMCTS with oxygen carrier gas. As the input energy increased, the deposition rate of SiOx film increased. The plasma diagnostics were performed by optical emission spectrometry. The deposition rate was characterized by alpha-step. The mechanical properties of the coatings were examined by nano-indenter and pencil hardness, respectively. The deposition rate of the SiOx films could be controlled by the appropriate intensity of excited neutrals, ionized atoms and UHF input power with HF bias at room temperature, as well as the dissociation of OMCTS.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1890-1892
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• 2002

The technology of sulfur lamps that has physical and electrical characteristics comparable to current HID source has been reported. The fundamental principles of the operation of microwave discharges that are used to convert microwave energy to broad spectrum visual light are known. In this paper, emission dependance of microwave discharges in mixture content of sulfur with noble gases was studied. It is shown that the excitation of this gaseous mixture is carried out in two phases: (l) ionization of noble gas atoms by a microwave field and (2) the consequent maintenance of slightly ionized nonequilibrium plasma by the field. These two processes have essentially various thresholds for the microwave pump. The purpose of this work is to investigate spectral properties of the high frequency discharges in a mixture sulfur vapors with noble gases.

• 천문학회지
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• 제47권5호
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• pp.179-185
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• 2014

We study the physical and chemical properties of the molecular clump hosting a young stellar cluster, IRAS 20160+3636, which is believed to have formed via the "collect and collapse" process. Physical parameters of the UC H II region associated with the embedded cluster are measured from the radio continuum observations. This source is found to be a typical Galactic UC H II region, with a B0.5 type exciting star, if it is ionized by a single star. We derive a CN/HCN abundance ratio larger than 1 over this region, which may suggest that this clump is being affected by the UV radiation from the H II region.

• 한국환경과학회지
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• 제21권3호
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• pp.363-368
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• 2012

The influence of plasma discharge on the nutrient components ($NO_3$-N, $NH_4$-N, $PO_4$-P, K, Ca, and Mg) and water quality [pH, ORP (oxidation-reduction potential) and electric conductivity] of hydroponic water were investigated. It was observed that the $NH_4$-N, $PO_4$-P, K, Ca, and Mg were kept at the constant concentrations for plasma discharging of 90 min. On the other hand, $NO_3$-N concentration was increased with proceeding of the plasma discharge. The increase of $NO_3$-N concentration was considered with the fact that nitric acid was created from nitrogen among supplying air for the insulation of inside of dielectric barrier. ORP and electric conductivity was increased with plasma discharging time. However, pH was decrease with what because of the generation of the nitric acid. When adjusting the hydroponic ingredients, pH and conductivity must to be considered because of the change of pH and conductivitiy with the discharging.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.327-328
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• 2017

This paper presents the power supply system which is made of three units: the capacitor charging and main pulse unit, simmer power supply unit, and series trigger unit. The capacitor charging and main pulse unit charges the capacitor bank by using the series parallel resonant converter and the generated main pulses apply to the lamp. The series trigger unit ionize the xenon gas located in the lamp and the simmer power supply unit sustains the ionized condition. It means that the lamp lifetime and efficiency are advanced by reducing the number of triggering. Not only the operation of the proposed system but also the performance of each unit will be verified by the experimental results.

• 한국재료학회지
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• 제6권4호
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• pp.379-387
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• 1996

본 연구에서는 GaAs 소자제작 및 epi-layer 성장 공정에 있어 이용되어지는 HCI, H3PO4, 탈이온수(de-ionized water:DIW)를 통한 습식제정후 공기중 노출에 따른 오염을 최소화하여 표면상태 변화를 진성적(intrinsic)으로 관찰하고자 모든 세정처리를 아르곤 가스(argon gas)로 분위기가 유지되는 glove box에서 수행하였으며, 표면조성 및 결합상태 변화에 대한 관찰은 X-선 광전자 분광기(X-ray photoelectron spectroscopy)를 통해 이루어졌다. 고진공하에서 GaAs를 벽개하여 관찰함으로써 Ga이 대기중 산소이온과 우선적으로 결합함을 알 수 있었고, 이런 GaAs 표면의 반응성에 대한 고찰을 바탕으로 습식세정에 따른 화학반응 기구가 제시 되어졌다. HCI 및 H3PO4/DIW/HCI처리후 CI-이온의 Ga 이온과의 반응에 의한 Ga-CI결합의 형성과 As 산화물의 높은 용해도에 따른 As 산화물의 완전한 제거 및 식각전 초기(bare)GaAsvyaus에 존재하는 원소(elemental)As 상태의 식각후 잔류가 관찰되어졌다. 또 HCI, H3PO4/DIW/HCI 처리하고 DIW로 세척후 표면상태 변화를 관찰한 결과, DIW처리에 의해 elemental As 상태가 증가함을 알 수 있었다.