• 한국입자에어로졸학회지
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• 제8권4호
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• pp.133-141
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• 2012

A new depth filter media was designed and samples of flat sheet as well as cartridge assembly were prepared and tested to evaluate the filtration performance and compare with the commercial product. The arrangement of the depth filter media layers is important to reach the optimal filtration parameters like filter pressure drop, particle collection efficiency and dust holding capacity. Initially, both flat sheet samples of new media and commercial product have been tested using standard test units. Tests with new depth filter media cartridges of various pleat count were conducted in order to find the optimal pleat count which would represent the lowest pressure drop. These tests give an insight on how the pleat count and the assembly configuration affect the performance of the depth filter media cartridge. By comparing the samples with a commercial product we could confirm relatively high filtration performance of the sample cartridge with pleat count 150 made of new depth filter media. The cartridge with the same pleat count exhibits better performance without the outer mesh.

• 천문학회지
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• 제47권4호
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• pp.159-161
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• 2014

The jet production efficiency of radio galaxies can be quantified by comparison of their kinetic jet powers $P_{jet}$ and Bondi accretion powers $P_B$. These two parameters are known to be related linearly, with the jet power resulting from the Bondi power by multiplication with an efficiency factor of order 1%. Using a recently published (Nemmen & Tchekhovskoy 2014) high-quality sample of 27 radio galaxies, I construct a $P_B$ - $P_{jet}$ diagram that includes information on optical AGN types as far as available. This diagram indicates that the jet production efficiency is a function of AGN type: Seyfert 2 galaxies seem to be systematically (with a false alarm probability of $4.3{\times}10^{-4}$) less efficient, by about one order of magnitude, in powering jets than Seyfert 1 galaxies, LINERs, or the remaining radio galaxies. This suggests an evolutionary sequence from Sy 2s to Sy 1s and LINERs, controlled by an interplay of jets on the one hand and dust and gas in galactic nuclei on the other hand. When taking this effect into account, the $P_B$ - $P_{jet}$ relation is probably much tighter intrinsically than currently assumed.

• 천문학회보
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• 제38권2호
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• pp.35.1-35.1
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• 2013

By probing nuclear regions and overall properties of AGN hosts as a function of their environments, we aim to observationally examine how AGN activities are related to their surroundings. We have selected eight representative AGN hosts in the Virgo cluster, including seven cluster members (M49, M60, M84, M87, NGC 4435, NGC 4526, NGC 4636) and one galaxy that is likely to be background (NGC 4261) but still close enough to be studied in high resolution. The selected galaxies are located in a range of density regions showing various morphology in 1.4 GHz continuum. High resolution observations with the KVN allow us to access the inner region of the AGN without suffering from dust extinction and synchrotron self-absorption. Since half of our targets are weak to be detected at K-band within its coherence time, we applied phase referencing (fast antenna position switching) to calibrate fast atmospheric phase fluctuations. We successfully detected relatively bright AGNs, such as M87, M84 and NGC4261, but no detection signature was found to the other members of the sample. In this talk, we will present our first results from our KVN observations, while we will discuss in detail the applied technique and our immediate future plans.

• 천문학회보
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• 제39권2호
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• pp.53.2-53.2
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• 2014

Radial color gradient of early type galaxies (ETGs) is a key tool for studying the evolution of these galaxies. In this work, we investigated whether ETGs having negative or positive color gradients show any distinguishable characteristics in the galaxy properties. We selected sample of 211 ETGs at 0.01 < z < 0.5 in the Spitzer FLS field, then we constructed u-R color gradients. We obtained the stellar mass, specific star formation rate and fluxes of emission lines of each ETG from MPA-JHU DR7 catalog. Spitzer IRAC and MIPS 24 micron data were used to detect dust emission from the ETGs. Preliminary result shows that less massive galaxies are likely to have positive color gradients, which is probably due to the ongoing star formation in the galaxy core. Almost all AGNs have negative color gradients. This probably is because AGNs are located in relatively massive galaxies with little ongoing star formation. There exists a marginal difference in the percentage of galaxies with PAH emission between ETGs having positive color gradient and negative color gradient. This also supports that ETGs with positive color gradient are galaxies having enhanced star formation.

• 천문학회보
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• 제39권2호
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• pp.58.1-58.1
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• 2014

Energetic gas outflows from active galactic nuclei (AGNs) may have a crucial role in galaxy evolution. In this contribution, we present a census of ionized gas outflows using a large sample (~23,000) of local (z < 0.1) type-2 AGNs selected from the Sloan Digital Sky Survey DR 7. By measuring the velocity offset of narrow emission lines, i.e., [O III] ${\lambda}5007$ and the Balmer lines, with respect to the systemic velocity measured from the stellar absorption lines, we find ~47% of AGNs showing an [O III] line-of-sight velocity offset ${\geq}20km\;s-1$. The fraction in type-2 AGNs is similar to that in type-1 AGNs after considering the projection effect. AGNs with larger [O III] velocity offsets, in particular with no or weak $H{\alpha}$ velocity offsets, tend to have higher Eddington ratios, implying that the [O III] velocity offset is related to on-going black hole activity. Also, we find the different distributions of the host galaxy inclination between the AGNs with blueshifted [O III] and the AGNs with redshifted [O III], supporting the model of biconical outflow with dust obscuration. Meanwhile, for ~3% of AGNs, [O III] and $H{\alpha}$ exhibit comparable large velocity offsets, suggesting a more complex gas kinematics than decelerating outflows in the narrow-line region.

• 공업화학
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• 제5권2호
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• pp.337-344
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• 1994

높은 연소효율과 환경오염물질을 적게 배출하는 75kw급 소형 접선방향 연료주입식 수직형 사이클론 연소기를 이용하여 성상이 다른 수입 유연탄(역청탄, 아역청탄)을 시료로 하여 공기비 0.4~1.6 범위에서 각각의 연소 특성 및 연소 후 회분의 포집효율을 조사하였다. 로 내 온도 분포는 전영역에서 역청탄이 아역청탄보다 약 $100^{\circ}C$ 이상 높게 나타났고 로 내에서는 로 하부와 축선이 높게 나타났다.

• Journal of Welding and Joining
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• 제32권1호
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• pp.102-107
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• 2014

SCR(Thyristor) type $CO_2$ welders have widely used for the welding process of heavy industries such as shipbuilding and plant. Since the industrial fields of shipbuilding and plant are usually exposed to severe welding condition with lots of dust, extreme temperature, high humidity and vibration, it is not recommended to use inverter type welder despite its state-of-the-art technology. Many sophisticated functions in the inverter welder may not work due to malfunction of its sensitive components. Hence this study focused on digitalization of SCR $CO_2$ welder by making use of microprocessor for SCR phase control. By this application, fine control of output of the $CO_2$ welding systems is achieved. Also pulse output mode of operation is realized and its verification is carried out with aluminum sample welding. The experimental results showed sound weld bead. The front operation panel provide user with numerical parameter settings and monitors. It will help precise weld process monitoring and control with digital value.

• Journal of Microbiology and Biotechnology
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• 제5권3호
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• pp.138-142
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• 1995

Bacillus thuringiensis strain BT-209 was isolated from a soybean grain dust sample in Korea. The strain BT-209 produced two different sizes of cuboidal crystals and one spore in the cell. In the biochemical characterization, the strain BT-209 showed negative reactions on the production of urease, and the utilization of citrate and sucrose. Examination of its antibiotic resistance revealed that while the strain BT-209 showed higher sensitivity than B. thuringiensis subsp. kurstaki HD-1 to ampicillin, bacitracin, chlortetracycline, gentamycin, neomycin, penicillin G, tetracycline and tobramycin, it was more resistant to methicillin than B. thuringiensis subsp. kurstaki HD-1. The $\delta$-endotoxin crystal of strain BT-209 consisted of three proteins with apparent molecular weights of appoximately 148, 135 and 62 kDa on a 10% SDS-PAGE. The strain BT-209 had at least eight different plasmids with sizes of 4.1, 5.2, 6.3, 8.6, 14.6, 24.5, 67.6 and 77.6 Kb. The strain BT-209 showed strong lethalities of 70% and 87% against Bombyx mori and Hyphantria cunea larvae. at 72 h, respectively.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제36회 춘계학술대회논문집
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• pp.425-429
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• 2011

높은 레이저 복사 조도에 발생되는 금속 플라즈마의 발달 과정과 레이저 펄스 이후의 shadowgraph를 이용해 공기 중에서의 데토네이션과 연소 현상에 대해 연구되었다. 본 논문의 가장 중요한 점은 높은 레이저 에너지에 의해 삭마 된 알루미늄 플라즈마와 공기로부터의 산소와의 화학반응의 진행을 XRD를 통해 관측한 것이다. 또한 레이저를 통해 유도된 화학적 반응 파와 공기 중에서의 알루미늄 분진 폭발의 데토네이션과의 양적인 평가를 유도하였다. 이러한 연구는 덩어리 상태의 금속 샘플에서 산화제를 필요로 하지 않고 데토네이션을 발생시키는 새로운 방법을 제시할 것으로 여겨진다.

• 한국버섯학회지
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• 제18권4호
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• pp.393-397
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• 2020

Mycelium composites and leathers have versatile material properties based on their composition and manufacturing process. To prepare mycelium mat for the production of mushroom leather, several strains were mutated by gamma rays. Some mutant strains, including Lentinula edodes, Ganoderma lucidium, and Schizophyllum commune showed good hyphae growth rate and density on saw-dust media. Irradiation power (Gy), time, and height from the radiation source to the sample were examined. Based on the preliminary data obtained in this study, comprehensive research should be conducted to explore the optimal strains and culture conditions for mycelium-based leather production.