• Title/Summary/Keyword: Ambient gas

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Study of Mössbauer Spectroscopy for Iron Oxides Synthesized by Pulsed Wire Evaporation (PEW) (전기선폭발법으로 제조된 철산화물의 뫼스바우어분광연구)

  • Uhm, Young Rang
    • Journal of the Korean Magnetics Society
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    • v.24 no.5
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    • pp.135-139
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    • 2014
  • Iron-oxide nanopowders were synthesized by a pulsed wire evaporation (PWE) in various ambient gas conditions. SEM measurement indicates that the spherical iron nanoparticles are about 50 nm in diameter. The phase analysis for the produced iron-oxide powders was systematically investigated by using $M\ddot{o}ssbauer$ spectra and the results show that classified phases of $Fe_2O_3$ and $Fe_3O_4$ can be controlled by regulating the oxygen concentration in the mixed gas during the PWE process. A quadrupole line on the center of $M\ddot{o}ssbauer$ spectrum represents the superparamagnetic phase of 12 % from ${\gamma}-Fe_2O_3$ phase.

Development of Portable Gas Chromatography / Photoionization Detector System (휴대용 기체 크로마토그래피 / 광이온화 검출기 시스템의 개발)

  • Kim, Man Gu;Sim, Ji Hui;Lee, Dong Su;Lee, Yong Geun
    • Journal of the Korean Chemical Society
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    • v.38 no.2
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    • pp.151-159
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    • 1994
  • The portable gas chromatography system was developed which was consisted of ambient vapor sampler(AVS), short capillary column(3 m long, 0.32 mm i.d. GC(SCCGC), photoionization detector (PID) and vacuum pump which was operated at subambient pressure. The seletion of capillary column was based on the theoretical calculation from Golay equation. The pressure ratio of column inlet and outlet appropriated between 1.03 and 1.2 in the system. The available column flow were 0.87∼4.63 ml/min at the pressure ratios. The AVS consisted of three concentric tubes and enables rapid, repetitive introduction of vapor samples directly into capillary column and showed good reproducibility. The subambient column outlet pressure with PID resulted in a significant increase in the optimum column flow, permitting rapid analysis. The baseline separation of m-xylene and o-xylene was able to within 40 second with the system. Parameters affecting the column resolving power were sampling duration, column length and diameter, and the pressure ratio. Effects of these parameters were investigated using bezene derivative compounds.

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PRE-PROCESSING OF GALAXIES IN THE FILAMENTS AROUND THE VIRGO CLUSTER

  • YOON, HYEIN;CHUNG, AEREE;SENGUPTA, CHANDREYEE;WONG, O. IVY;BUREAU, MARTIN;REY, SOO-CHANG;VAN GORKOM, J.H.
    • Publications of The Korean Astronomical Society
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    • v.30 no.2
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    • pp.495-497
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    • 2015
  • Galaxies can be "pre-processed" in the low-density outskirts by ambient medium in the filaments or tidal interactions with other galaxies while falling into the cluster. In order to probe how early on and by which mechanisms galaxies can be affected before they enter high-density cluster environments, we are carrying out an atomic hydrogen ($H\small{I}$) imaging study of a sample of galaxies selected from three filamentary structures around the Virgo cluster. Our sample consists of 14 late-type galaxies, which are potentially interacting with their surroundings. The $H\small{I}$ observations have been done using the Westerbork Synthesis Radio Telescope, the Giant Metrewave Radio Telescope, and the Jansky Very Large Array with column density sensitivity of ${\approx}3-5{\times}10^{19}cm^{-2}$ in $3{\sigma}$ per channel, which is low enough to detect faint $H\small{I}$ features in the outer disks of galaxies. In this work, we present the Hi data of two galaxies that were observed with GMRT. We examine the $H\small{I}$ morphology and kinematics to find the evidence for gas-gas and/or tidal interactions, and discuss which mechanism(s) could be responsible for pre-processing in these cases.

Dependence of the Formation of $TiO_{2\pm}{\delta}$ Films on Plasma Process Variables (플라즈마 공정 변수가 $TiO_{2\pm}{\delta}$ 박막 형성에 미치는 영향)

  • Park, Sang-Gi;Gang, Bong-Ju;Lee, Won-Hui;Lee, Jae-Gap
    • Korean Journal of Materials Research
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    • v.10 no.11
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    • pp.732-737
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    • 2000
  • Plasma enhanced chemical vapor deposition of $TiO_{2$\pm}{\delta}$ has been carried out using TEMAT [tetrakis(ethylmethylamido) titanium] and $H_2$. Increasing the power from 300 W to 500 W produced the high density plasma, leading to the formation of TiO$_2$films with an increased ratio of Ti to O and a negligible amount of C and N. Applying the bias of 30W to the substrate in creased the growth rate of the film with a slightly increased content of Ti in the film. In addition, $H_2O$ was from either the residual gas in the gase pressure or $H_2(/He)$ gas and actively participated in the formation of $TiO_2$ films. Consequently, Ti ions created in the plasma could be a main contributor to $TiO_2$ formation with a slight amount of $H_2O(~10^{-4}Toor)$ in the ambient, which provided the dissociation of TEMAT.

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Experimental Study on the Biofiltration of Toluene Gas (기상 톨루엔의 생물학적 여과에 관한 실험적 연구)

  • 홍성도;명성운;최석호;김인호;이현재;구본탁
    • KSBB Journal
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    • v.15 no.5
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    • pp.469-473
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    • 2000
  • We studied the removal of toluene vapors in a lab-scale biofiter. Biofiltration was performed in a column fed in a downflow manner with contaminated air at ambient conditions. The column was packed with a mixture of peat and calstone(5:3 vol. Ratio), which was inoculated with microbes of selected stains(Pseudomonas putida type A). The microorganisms were immobilized on the filter media and biofilms were formed. The fiofilter was operated at various inlet toluene concentrations for days, and treated up to a maximum elimination capacity of $20 g/m^3hr$ at an inlet load of $30 g/m^3hr$, which corresponds to removal efficiencies in the range 20∼90% and a gas retention time of 1 to 2 min. The pressure drop was almost negligible over the biofilter columns, amounting to only $1.062 cmH_2O/m$ and appreciably smaller than other studies. The effects of operating conditions such as flow rate, inlet toluene concentration and moisture content on the performance of the biofilter were sequentially investigated.

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Enhancement of Carbon Dioxide Fixation by Alteration of Illumination during Chlorella Vulgaris-Buitenzorg's Growth

  • Wijanarko Anondho;Dianursanti Dianursanti;Gozan Misri;Andika Sang Made Krisna;Widiastuti Paramita;Hermansyah Heri;Witarto Arief Budi;Asami Kazuhiro;Soemantojo Roekmijati Widaningroem;Ohtaguchi Kazuhisa;Koo Song-Seung
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.11 no.6
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    • pp.484-488
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    • 2006
  • Alteration of illumination with optimum carbon dioxide fixation-based curve in this research successfully enhanced the $CO_{2}-fixation\;(q_CO_{2}$ capability of Chlorella vulgaris Buitenzorg cultivated in a bubble column photo bioreactor. The level of $CO_{2}$ fixation was up to 1.91 times that observed from cultivation with intensification of illumination on an optimum growth-based curve. During 144 h of cultivation, alteration of light intensity on an optimum $CO_{2}-fixation-based$ curve produced a $q_CO_{2}$ of $12.8\;h^{-1}$. Meanwhile, alteration of light intensity with a growth-based curve only produced a $q_CO_{2}$ of $6.68\;h^{-1}$. Increases in light intensity based on a curve of optimum $CO_{2}-fixation$ produced a final cell concentration of about 5.78 g/L. Both cultivation methods were carried out under ambient pressure at a temperature of $29^{\circ}C$ with a superficial gas velocity of $2.4\;m/h(U_{G}$. Cells were grown on Beneck medium in a 1.0 L Bubble Column Photo bioreactor illuminated by a Phillips Halogen Lamp (20 W/12 V/50 Hz). The inlet gas had a carbon dioxide content of 10%.

A Study on the Deposition of Boron Phosphide at the Low Temperature using CVD Method and its Characteristics (CVD법을 이용한 보론 포스파이드의 저온 층착과 특성에 관한 연구)

  • 윤여철;김순영;박윤권;강재경;김철주
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.07a
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    • pp.103-107
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    • 2000
  • Boron Phosphide films were deposited on the glass substrate at the low temperature, 55$0^{\circ}C$, by the reaction of B$_2$H$_{6}$ with PH$_3$ using CVD. $N_2$ was employed as carrier gas. The optimal gas rates were 50 $m\ell$/min for B$_2$H$_{6}$, 50 $m\ell$/min for PH$_3$ $m\ell$/min and 1.5 $\ell$/min for $N_2$. To investigate the annealing effect, the films were annealed for 1hour, 3hours in $N_2$ambient at 55$0^{\circ}C$ and tested. The deposition rate was 1000$\AA$/min and the refractive index of film was 2.6. The measurement of X-RD shows that the films have the preferred orientation of (1 0 1) and the intensity of the peak for (1 0 1) orientation decreases according to the annealing time. The data of VIS spectrophotometer proved that the films are transparent in the visible range and the maximal transmittance increases according to the annealing time; 75.49% for as-deposited, 76.71% for 1hr-annealed and 86.4 % for 3hrs-annealed. The measurement of AFM shows that the average surface roughness increases according to the annealing time; 73$\AA$ for as-deposited, 88.9$\AA$ for 1hr-annealed and 220$\AA$ for 3hrs-annealed. Also, The data of the secondary electron emission rate(Υ) shows that the secondary electron emission rate increases according to the annealing time; 0.317 for 1hr-deposited, 0.357 for 1hr-annealed and 0.537 for 3hrs-annealed. And, The measurement of FT-IR that the characteristic of transmittance in the infrared range was stabilized through annealing.ing.

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Comparison of Combustion Characteristics With and Without Water Tube Simulating Heat Exchanger in Two Sections Porous Media Burner (2단 다공성 매체버너에서 열교환기를 모사한 수관 유무에 따른 연소 특성 비교)

  • Lee, Hui-Do;Kim, Jae-Hyeon;Lee, Kee-Man
    • Journal of the Korean Institute of Gas
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    • v.23 no.5
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    • pp.24-34
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    • 2019
  • In this study, the experimental studies were conducted to analyzing characteristics of combustion and flame stabilizing according to with and without water tube in boiler. The burner has consisted of SiC foam where has the location of submerged flame between a ceramic board acting as flash-back arrestor. Porous burner is also insulated to minimize heat loss in the radial direction. In the condition of fixed equivalence ratio, the flame mode was divided into three stability zones by the flow rate. The main factor for blow-off and flash-back depends on mixture flow rate. Consequently, the case of burner with water-tube has higher NOx emissions than without case. This result explains that the presence of water-tube makes the heat loss resistant to ambient temperature with increasing of NOx. This tendency was proved by predicting the relationship between O2 emission and NO production rate, and by analysing temperature profiles.

A Study on the Physical Characteristics of III-V Compound Boron Phosphide using CVD (CVD를 이용해 증착한 III-V 화합물 보론 포스파이드의 물성분석에 관한 연구)

  • Hong, Kuen-Kee;Kim, Chul-Ju
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07a
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    • pp.332-335
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    • 2004
  • Boron Phosphide films were deposited on(III) Si substrate at $650^{\circ}C$, by the reaction of $B_2H_6$ with $PH_3$ using CVD. $N_2$ was employed as carrier gas. The optimal gas rates were 20 ml/min for $B_2H_6$, 60 ml/min for $PH_3$ ml/min and $1{\ell}/min$ for $N_2$. The films were annealed for 1hour in $N_2$ ambient at $550^{\circ}C$ and measured. The measurement of AFM shows that the average surface roughness is each $10.108{\AA}$ and $29.626{\AA}$. So, we could know every commonplace thing. The measurement of XRD shows that the films have the preferred orientation of(1 0 1). From SEM images, we could see that Boron Phosphide is showed of a structure, which is grain size, which is grain boundary size. Also, the measurement of AES is shown the films have $B_{13}P_2$ Stoichiometry. From WDX See that ingredient is detected each Boron and Phosporus. So, we could see that deposited BP thin film. In this study, we obtained the BP thin film by deposited in atmosphere pressure, and known to applicate as microwave absorbtion material of BP thin film.

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Evaluation of Cryogenic Compressive Strength of Divinycell of NO 96-type LNG Insulation System (NO96타입 LNG 방열시스템 Divinycell의 극저온 압축 강도 평가)

  • Choe, Yeong-Rak;Kim, Jeong-Hyeon;Kim, Jong-Min;Park, Sungkyun;Park, Kang Hyun;Lee, Jae-Myung
    • Journal of Ocean Engineering and Technology
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    • v.30 no.5
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    • pp.349-355
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    • 2016
  • Divinycell, which functions as both insulation and a supporting structure, is generally applied in the NO96-type liquefied natural gas (LNG) insulation system. Polymer-material-based Divinycell, which has a high strength and low weight, has been widely used in the offshore, transportation, wind power generation, and civil engineering fields. In particular, this type of material receives attention as an insulation material because its thermal conductivity can be lowered depending on the ambient temperature. However, it is difficult to obtain research results for Divinycell, even though the component materials of the NO96-type LNG cargo containment system, such as 36% nickel steel (invar steel), plywood, perlite, and glass wool, have been extensively studied and reported. In the present study, temperature and strain-rate dependent compressive tests on Divinycell were performed. Both the quantitative experimental data and elastic recovery are discussed. Finally, the mechanical characteristics of Divinycell were compared to the results of polyurethane foam insulation material.