• Journal of the KSME
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• v.20 no.1
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• pp.40-51
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• 1980

근래 음향학(acoustics)이 기계공학과의 일전정과목으로 등장하여 일시 미국에서 과학공학종의 취직난이 있었을 때에도 음향학전공생들은 직장을 얻게되었다. 연이나 음향학과 유체역학의 상 호관념은 그 기초적연구에서나 응용에서는 특수한 항공공학계에서 관심을 둔 분유소음(jet noise) (Blumenthal, Russell과 Streckenabach(1975)과 Banerian(1978) 참조) Sonic boom(Carlson과 Maglieri(1972) 참조) 또 미해군에서 주목한 흐름의 소음 (flow noise) 같은 부분이외에는 별로 큰 진전을 보지못하고 있다. 그러므로 음향하종에게나 유체역학전문가에게는 많은 과제가 남 겨있다. 음향은 유역에 변화를 일으키고 흐름의 특성을 변시키므로 이 문제에 대하여 유체역학 견지로써 알아보고져 한다.

• Publications of The Korean Astronomical Society
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• v.21 no.2
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• pp.35-42
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• 2006

We report a high resolution spectrum of AG Pegasi observed at Bohyunsan Optical Astronomy Observatory (BOAO) on October 2, 2004. Some of permitted emission lines, for example H I, He I, He II, Fe II and Ti II were observed in the spectrum of AG Pegasi in 2004. Lines presented in the longer wavelength region than $6500{\AA}$ are identified. And radial velocities for each element are measured. Then we carefully discuss the geometrical feature of AG Pegasi in October 2004.

• Economic and Environmental Geology
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• v.28 no.2
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• pp.109-121
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• 1995

The hydrothermal vein type deposits which comprise the Kasihan, Jompong and Gempol mineralized areas are primarily copper and zinc deposits, but they are also associated with lead and/or gold mineralization. The deposits occur within the Tertiary sedimentary and volcanic rocks in the Southern Mountain zone of the eastern Java island, Indonesia. Mineralization can be separated into two or three distinct stages (pre-and/or post- ore mineralization stages and main ore mineralization stage) which took place mainly along pre-existing fault breccia zones. The main phase of mineralization (the main ore stage) can be usually classified into three substages (early, middle and late) according to ore mineral assemblages, paragenesis, textures and their chemical compositions. Ore mineralogy and paragenesis of the three areas in the district are different from each other. Pyrite, pyrrhotite (/arsenopyrite), iron-rich (up to 20.5 mole % FeS) sphalerite and (Cu-)Pb-Bi sulfosalts are characteristic of the deposits in the Kasihan (/Jompong) area. On the other hand, pyrite + hematite + magnetite + iron-poor (2.7 to 3.6 mole % FeS) sphalerite assemblage is restricted to the Gempol area. Fluid inclusion data suggest that fluids of the main ore stage evolved from initial high temperatures (near $350^{\circ}C$) to later lower temperatures (near $200^{\circ}C$) with salinities ranging from 0.8 to 10.1 equiv. wt. percent NaCl. Each area represents a separate hydrothermal system: the mineralization at Kasihan and Jompong were largely due to early fluid boiling coupled with later cooling and dilution, whereas the mineralization at Gempol was mainly resulted from cooling and dilution by an influx of cooler meteoric waters. Fluid inclusion evidence of boiling indicates that pressures of ${\geq}95$ to 255 bars (${\geq}95$ bars for the Gempol area: $\approx$ 120 to 170 bars for the Jompong area: $\approx$ 140 to 255 bars for the Kasihan area) during portions of main ore stage mineralization. Equilibrium thermodynamic interpretation indicates that the evolution trends of the temperature versus fS2 variation of ore stage fluids in the Pacitan district follow two fashions: ore fluids at Kasihan and Jompong changed from the pyrite-pyrrhotite sulfidation stage towards pyritehematite- magnetite state, whereas those at Gempol evolved nearly along pyrite-hematite-magnetite reaction curve with decreasing temperature. The sulfur isotope compositions of sulfide minerals are consistent with an igneous source of sulfur with a ${\delta}^{34}S_{{\Sigma}s}$ value of about 3.3 per mil. The oxygen and hydrogen isotopic compositions of the fluids in each area indicate a progressive shift from the dominance of highly exchanged meteoric water at early hydrothermal systems towards an un- or less-exchanged meteoric water at later hydrothermal systems.

• Publications of The Korean Astronomical Society
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• v.15 no.spc1
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• pp.147-151
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• 2000

Symbiotic stars, believed to be binary systems of a mass-losing giant and a white dwarf with an emission nebula, are known to exhibit very broad wings around Hex that extend to $\~10^3km\;s^{-1}$. The wing formation mechanism is not a settled matter and recently Lee (2000) proposed that Raman scattering of Ly$\beta$ by neutral hydrogen is responsible for the broad H$\alpha$ wings. In this model, it is predicted that. the Hex wings will be polarized depending on the geometric and kinematic distribution of the scatterers relative to the UV emission region. In this paper, we investigate the polarization of Hex wings in symbiotic stars. Noting that many symbiotic stars possess bipolar nebular morphology, we assume that the distribution of neutral scatterers follows the similar pattern with a receding velocity of several tens of km $s^{-1}$ that mimics the expansion of the neutral envelope of the nebula. It is found that the red wing is more strongly polarized than the blue and main part and that the polarization direction is along the equatorial plane. We obtain a typical degree of polarization $\~10$ percent, however, it varies depending on the detailed distribution of H I scatterers We conclude that spectropolarimetry will provide very important information on the origin of the Hex wings.

• Publications of The Korean Astronomical Society
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• v.15 no.spc1
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• pp.133-145
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• 2000

Symbiotic stars are known as binary systems with both cool and hot components with enshrounding nebulous gas. The cool component, M-type giant, is presumably loosing its mass into a hot white or main sequence companion star through the inner Lagrangian point. The lines emit from the ionized nebulous region around the hot star while the mass loss or accretion activity is believed to be the main cause of sudden variation of the continuum and line fluxes. We selected 17 symbiotics for which the emission line fluxes were measured from the IUE SWP, LWR data, to find variability of spectrum. We also investigated the periodic variation of emissions or eclipsing effect from the IUE lines. All of our symbiotics show very high electron densities in the emission regions. For other optical symbiotics, the observations had been carried in 1999 with BOAO mid-resolution spectrometer. We classified symbiotics based on their outburst activities, or emission line characteristics, i.e., $OVI{\lambda}6830.\;The\;OVI{\lambda}6830$ emission lines are also found in S-type symbiotics, which have been known as charateristics of D-types.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.42-42
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• 2021

한강 자연성 회복은 사회환경을 고려한 한강의 생태적 기능회복과 복원, 자연의 복원력을 기반으로 한 사람이 공생 공존하는 새로운 관계로의 전환점을 의미하고 있다. 본 연구에서는 한강 유역권 산·학·연 관계자 100명을 대상으로 설문조사를 실시하여 한강 자연성 회복 비전과 추진전략을 도출한 결과, '맑은 물이 흐르는 강'(1순위), '더불어 사는 강'(2순위), '생명이 숨쉬는 강'(3순위), '살아 움직이는 강'(4순위)으로 정책방향을 수립할 수 있었다. 또한 설문조사의 결과를 바탕으로 AHP 및 델파이 분석을 통해 한강 상류, 중류(서울권, 경기권), 하류별 자연성 회복 평가지표간 가중치를 산정하여 주요 추진과제를 선정하였다. 상류유역에서는 비점오염원 관리를 통한 환경오염 감소, 중류 유역에서는 도심하천의 수질관리강화 및 물 순환 체계 개선, 하류 유역에서는 생물다양성 확보 및 상·하류 지역 협력을 통한 상수원 수질 개선의 방안 필요의 결과가 도출되었다. 본 연구를 통하여 한강의 하천관리정책은 이수·치수 중심의 하천조성에서 하천생태복원 및 강과 사람과의 공존과 공생이 조화를 이룬 하천조성으로 관점이 변화되었음을 확인할 수 있었으며, 가중치 평가를 통한 최적 조합의 하천 관리방안이 도출되었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.12
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• pp.2697-2704
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• 2011

In tissue engineering area, researchers observe symbiotic relationship such as proliferation, interaction, division apoptosis with time between cells in process of the 3D cell culture in hydrogels. The 3D cell culture process can be taken photographs into sliced images using confocal microscope. Symbiotic mechanism and changes of cell behaviors can be observed and analyzed from the images acquired by confocal microscope. In this paper, we proposed and developed graded noise elimination method and cluster boundary extraction method to extract boundaries information from sliced confocal images acquired in process of the 3D cell culture in hydrogels. The experiment based algorithm showed excellent performance for eliminating noises that have very small millet-shaped size. It is also showed to extract exact boundaries information for even complex clusters.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.155-162
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• 2009

A cultivation-based approach was employed to compare the culturable bacterial diversity associated with two phylogenetically closely related marine sponges, Spirastrella abata and Spirastrella panis, which have geologically overlapping distribution patterns. The bacteria associated with sponge were cultivated using MA medium supplemented with 3% sponge extracts. Community structures of the culturable bacteria of the two sponge species were analyzed with PCR-RFLP (restriction fragment length polymorphism) based on 16S rDNA sequences. The RFLP fingerprinting of 16S rDNA digested with HaeIII and MspI, revealed 24 independent RFLP types, in which 1-5 representative strains from each type were partially sequenced. The sequence analysis showed >98.4% similarity to known bacterial species in public databases. Overall, the microbial populations of two sponges investigated were found to be the members of the classes; Alphaproteobacteria, Gammaproteobacteria, Firmicutes, and Actinobacteria. The Alphaproteobacteria were predominant in the bacterial communities of the two sponges. Gammaproteobacteria represented 38.5% of bacterial community in S. abata. Whereas only 1.6% of this class was present in S. panis. Bacillus species were dominat in S. panis. Bacillus species were found to be 44.3% of bacterial species in S. panis, while they were only 9.7% in S. abata. It is interesting to note that Planococcus maritimus (8.1%, phylum Firmicutes) and Psychrobacter nivimaris (28.9%, phylum Gammaproteobacteria) were found only in S. abata. This result revealed that profiles of bacterial communities from the sponges with a close phylogenetic relationship were highly species-specific.

• Publications of The Korean Astronomical Society
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• v.15 no.spc1
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• pp.103-112
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• 2000

Symbiotic stars are known as binary systems of a giant with heavy mass loss and a white dwarf accompanied by an emission nebula. They often show bipolar nebulae, and are believed to form an accretion disk around the white dwarf component by attracting the slow but heavy stellar wind around the giant companion. However, the existence and physical properties of the accretion disk in these systems still remain controversial. Unique to the spectra of symbiotic stars is the existence of the symbiotic bands around $6830{\AA}$ and $7088{\AA}$, which have been identified by Schmid (1989) as the Raman scattered features of the O VI $1032{\AA}$ and $1038{\AA}$ doublet by atomic hydrogen. Due to the incoherency of the Raman scattering, these features have very broad profiles and they are also strongly polarized. In the accretion disk emission model, it is expected that the Raman features are polarized perpendicular to the binary axis and show multiple peak structures in the profile, because the neutral scatterers located near the giant component views the accretion disk in the edge-on direction. Assuming the presence of scattering regions outflowing in the polar directions, we may explain the additional red wing or red peak structure, which is polarized parallel to the binary axis. We argue that in the accretion disk emission model it is predicted that the profile of the Raman feature around $6830{\AA}$ is different from the profile of the $7088{\AA}$ because the O VI line optical depth varies locally around the white dwarf component. We conclude that the Raman scattered features are an important tool to investigate the physical conditions and geometrical configuration of the accretion disk in a symbiotic star.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.2
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• pp.165-172
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• 1996

Symbiotic effectiveness and significance of Bradyrhizobium japonicum strains in five serogroups which were consisted of three corresponding serotype strains, respectively, indigenous to Korean soils were evaluated in terms of utility of strain serogroup for symbiotic improvement on soybean plant. The nodulation by rhizobia of each serogroup on four soybean cultivars(Danweonkong, Kwangkyo, Pangsakong, and Eunhakong) was good in order of USDA 123 > YCK 150 > YCK 117 > YCK 141 > USDA 110 serogroup members. Shoot dry weight of soybean was relatively high with USDA 110 serogroup members as well as with YCK 141 serogroup members, whereas the effectiveness of USDA 123 serogroup members was the lowest among the serogroups examined. In particular, Pangsakong among soybeans inoculated with five-serogroup members was positively outstanding on nodulation and shoot dry weight of the plant. Overall, symbiotic parameters of serogroup members associated with soybean plant such as nodule number, nodule mass, $N_2$ase activity, and shoot dry weight showed significantly different responses at level of 1% probability among both rhizobial serogroups and soybean cultivars, respectively. The rate in symbiotic similarity of the members of each serogroup from F-test ($$P{\leq_-}0.05$$) was 100% for nodule No., 90% for $N_2$ase activity. and 80% for soybean shoot dry weight. Taken together, the results indicated that the serological grouping of B. japonicum could be strongly useful for improving the symbiotic effectiveness hetween soybean and Rhizobium.