• Ocean Science Journal
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• 제41권4호
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• pp.255-260
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• 2006

Long-term variability in the intermediate layer of the eastern Japan Basin has been investigated to understand the variability of water mass formation in the East Sea. The simultaneous decrease of temperature at shallower depths and oxygen increasing at deeper depths in the intermediate layer took place in the late 1960's sand the mid-1980's. Records of winter sea surface temperatures and air temperatures showed that there were cold winters that persisted for several years during those periods. Therefore, it was assumed that a large amount of newly-formed water was supplied to the intermediate layer during those cold winters. Close analysis suggests that the formation of the Upper Portion of Proper Water occurred in the late 1960's and the Central Water in the mid-1980's.

• 천문학회지
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• 제40권4호
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• pp.127-129
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• 2007

It is well known that water vapor maser emission at 22.2 GHz is associated with the earliest stages of both low- and high-mass star formation and it can be considered a reliable diagnostic of their evolutionary state. Bright Rimmed Clouds (BRCs) are clouds that have been compressed by an external ionization-shock front which focuses the neutral gas into compact globules. The boundary layer between the neutral gas and the gas ionized by the incident photons is often called "bright rim" but the clumps are sometimes classified also as speck globules or cometary globules depending on their appearance. Small globules with bright rims have been considered to be potential sites of star formation and have been studied in several individual regions. We present results from high resolution VLA observations searching for new candidates of recent star formation in bright-rimmed clouds/globules associated with IRAS point sources.

• 한국물환경학회지
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• 제22권6호
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• pp.1137-1143
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• 2006

In this study we investigated the removal characteristics of NOM and bromate formation characteristics in SOMT reactor. The system was recently developed as a novel ozone reactor and installed in SJ pilot plant. DOC values were decreased within 3% after treatment of 0.5~2.0 mg/L ozone dosage in SOMT reactor while the $UV_{254}$ value was 69% decreased at 2.0 mg/L ozone dosage. The composition of NOM was analysed by LC-OCD (Organic Cabon Detector) after ozone treatment in SOMT reactor to elucidate the variation of NOM character. Polysaccharide (more than 20,000 g/mol) fraction of NOM was decomposed while building blocks (350~500 g/mol) and neutral (less than 350 g/mol) fraction increased. Spiked bromide reacted with 0.5~2.0 mg/L ozone dosage in the SOMT reactor. The bromate formation was proportional to the ozone dosage ($R^2=0.978$) but not proportional to reaction time. The maximum concentration of formated bromate was not exceeded to 10% of spiked bromide concentration.

• 한국해양학회지
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• 제28권2호
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• pp.101-106
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• 1993

하계에 나타나는 황해저층내수에 간단한 3차원의 육면체 모델을 적용하여, 조석의 혼합작용과 쿠로시오수괴가 황해저층냉수의 형성에 주는 영향을 연구하였다. 본연구에 서는 수치모델의 기술적인 문제 때문에 조석의 혼합작용을 연직혼합계수로 매계변수화 하였다. 또한 연안을 따라 나타나는 수온전선은 조석의 혼합작용에 의해서 형성되도록 하였으며, 황해저층냉수의 남부에 나타나는 수온전선의 형성에는 고온의 쿠로시오수괴 를 고려하였다. 수치실험의 결과, 모델의 상층과 하층에서 수온분포의 영향이 반대로 나타났다. 상층에서는 모델의 중앙부에서, 하층에서는 연안해역에서 각각 상대적으로 고온의 수온분포가 나타났다. 해수의 순환형태 역시 상층과 하층 사이에 반대로서, 상 층에는 시계방향이, 하층에는 반시계방향의 순환이 나타났다.

• Bulletin of the Korean Chemical Society
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• 제17권9호
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• pp.781-786
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• 1996

Mass transport behavior of C60 films on electrodes with different thicknesses has been studied by an Electrochemical Quartz Crystal Microbalance (EQCM) during electrochemical reduction-oxidation processes in the presence of water. C60 films were found to be reduced in the presence of water and they remains quite stable. In thin films, the mass on electrode decreased after a complete cycle while X-ray Photoelectron Spectroscopy (XPS) study does not support the existence or formation of C60-epoxides during electrochemical reduction processes in the presence of water or oxygen.

• Journal of the korean society of oceanography
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• 제38권1호
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• pp.11-16
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• 2003

The three dimensional structure of thermohaline circulation in a D-plane is investigated using a conceptual two layer model and a scaling argument. In this simple model, the water mass formation region is excluded. The upper layer represents the oceans above the main thermocline. The lower layer represents the deep ocean below the thermocline and is much thicker than the upper layer. In each layer, geostrophy and the linear vorticity balance are assumed. The cross interfacial velocity that compensates for the deep water mass formation balances downward heat diffusion from the top. From the above relations, we can determine the thickness of the upper layer, which is the same as thermocline depth. The results we get is basically the same as that we get for an f-plane ocean or the classical thermocline theory. Mass budget using the velocity scales from the scaling argument shows that western boundary and interior transports are much larger than the net meridional transport. Therefore in the thermohaline circulation, horizontal circulation is much stronger than the vertical circulation occuring on a meridional plane.

• 한국해양공학회지
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• 제24권6호
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• pp.41-50
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• 2010

This study established a 3D ecosystem model composed of stratification considering the topographic heat accumulation effect and river outflow, and then applied this model to Jinhae, Masan Bay. Specifically, it reenacted the formation and developmental process of ODW according to the stratification by calculating the kinematic eddy viscosity and eddy diffusion coefficient of the stratification model. The results were used as input data for the ecosystem model and compared with DO, COD, I-N, and I-P, which is the standard index of ocean water quality. As a result, it was determined that COD and T-N are third grade and T-P is second grade standards for a natural environment.

• 한국양식학회지
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• 제18권2호
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• pp.115-121
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• 2005

본 연구는 통기방법과 배양수의 환수에 따른 담수산 rotifer B. calyciflorus의 내구란 형성을 조사하였고 0.5 톤 수조에서 내구란 대량 생산을 수행하였다. 산소와 공기를 공급한 실험구에 있어서 rotifer의 최고밀도와 유성생식률은 차이는 없으나 수정률과 내구란 형성은 공기를 공급한 실험구가 산소를 공급한 실험구보다 높게 나타났다. 배양수의 환수간격에 따른 실험에서 환수를 하지 않은 실험구가 rotifer 최고밀도와 내구란 형성은 환수를 한 실험구(매일 환수한 실험구)보다 높게 나타났지만 내구란 생산의 효율적인 측면에서 Chlorella 건조중량당 내구란 형성은 환수를 한 실험구(매일 환수한 실험구)에서 가장 높게 나타났다. 또한 0.5톤 수조에서 내구란의 총 생산량은 $51.8{\sim}57.9{\times}10^6$개로 나타났다. 본 연구의 결과를 종합하여 볼 때, 공기를 공급한 batch 배양이 담수산 rotifer, B. calyciforus의 내구란을 대량생산하는데 효과적인 방법인 것으로 판단된다. 또한 이종의 내구란 대량생산은 해수산 rotifer B. plicatilis와 B. rotundiformis와 비슷한 생산 효율을 보인 것으로 판단된다.

• 천문학회보
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• 제44권2호
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• pp.51.4-51.4
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• 2019

We started a systematic observational study of the 22 GHz water and 44 GHz class I methanol masers in 87 high-mass young stellar objects (HM-YSOs) as a KaVA large program (LP). The primary goal is to understand dynamical evolution of HM-YSOs and their circumstellar structures by measuring spatial distributions and 3-dimensional velocity fields of multiple maser species. In the first-year observations (2016-2017), we made snap-shot imaging surveys of 25 water and 19 methanol maser sources. In the second-year observations (2018-2019), we have carried out monitoring observations of 19 water and 3 methanol maser sources that were selected on the basis of the first-year survey results. By combining follow-up observations with VERA (distances), JVN/EAVN (6.7 GHz methanol masers), and ALMA cycles 3 and 6 (thermal lines/continuum), we will provide novel information on physical properties (density, temperature, size, mass), 3D dynamical structures of disk/jet/outflow/infalling envelope, and relationship between evolutionary of HM-YSOs. In this presentation, we will report the current status and future plans of our KaVA large program.

• 대한기계학회논문집B
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• 제20권3호
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• pp.1096-1105
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• 1996

A theoretical model of the frost formation has been presented to investigate the characteristics of the growth of frost layer by considering molecular diffusion of water vapor and heat generation caused by sublimation of water vapor in the frost layer. The present model was compared with existing experimental data as well as a previous model. The difference between the present model and existing experimental data was found to be about 6 percent. An analysis for the behavior of frost formation using present model shows a good agreement with the trend for a number of experimentally observed features. The present analysis can also provide the physical understanding on the phenomena of the frost formation.