• 한국수산과학회지
• /
• 제51권1호
• /
• pp.107-112
• /
• 2018

One-dimensional numerical model is implemented to investigate temperature variations in the mixed layer depth (MLD) with the passage of typhoons. In the model, we assume a non-divergent, infinite ocean and consider wind effects only, excluding isostatic effects (inverse barometric effects) and upwelling with vertical movement of the water column. Numerical experiments investigate the effects of typhoon tracks on temperature variations, including their dependence on vertical resolutions in the MLD and these results are compared with those in a three-dimensional primitive equation model (POM). The model reproduces features of the observed temperature variations in the MLD fairly well, and implies that wind effects, rather than isostatic effects, play a predominant role in temporal and spatial temperature variations in the MLD. After the passage of typhoons, however, the model does not reproduce well the temperature variations observed in the MLD, because a limitation of the model is its inability to reproduce events such as cyclonic eddy formation (Hong et al., 2011; Masuda and Hong, 2011). The model also shows well the so called 'rightward bias' (Price, 1981) of sea surface cooling which is the most predominant in the right hand side of typhoon's track.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 제5회 학술대회 논문집 일렉트렛트 및 응용기술연구회
• /
• pp.45-48
• /
• 2003

BiSrCaCuO thin films were fabricated by atomic layer-by-layer deposition using an ion beam sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to $SrBi_2O_4$ by in-situ anneal.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
• /
• pp.281-283
• /
• 2001

$Bi_{2}Sr_{2}CuO_{x}$(Bi-2201) thin films were fabricated by atomic layer-by-layer deposition using an ion bearn sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used with ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition. two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit. then three dimensional growth takes place. Since Cu element is the most difficult to oxidize. only Sr and Bi react with each other predominantly. and forms a buffer layer on the substrate in an amorphous-like structure. which is changed to $SrBi_{2}O_{4}$ by in-situ anneal.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 추계학술대회 논문집
• /
• pp.281-283
• /
• 2001

Bi$_2$Sr$_2$CuO$\_$x/(Bi-2201) thin films were fabricated layer-by-layer deposition using an ion beam sputtering method. 10 wt% and 90 wt% ozone mixed with oxygen were used ultraviolet light irradiation to assist oxidation. At early stages of the atomic layer by layer deposition, two dimensional epitaxial growth which covers the substrate surface would be suppressed by the stress and strain caused by the lattice misfit, then three dimensional growth takes place. Since Cu element is the most difficult to oxidize, only Sr and Bi react with each other predominantly, and forms a buffer layer on the substrate in an amorphous-like structure, which is changed to SrBi$_2$O$_4$ by in-situ anneal.

• 한국방사성폐기물학회:학술대회논문집
• /
• 한국방사성폐기물학회 2004년도 학술논문집
• /
• pp.32-42
• /
• 2004

Recently, plasma surface-cleaning or surface-etching techniques have been focused in respect of the decontamination of spent or used nuclear parts and equipment. In this study the removal rate of metallic cobalt surface is experimentally investigated via its surface etching rate with a $CF_4-o_2$mixed gas plasma. Experimental results reveal that a mixed etchant gas with about 80% $CF_4$-20% $O_2$ (molar) gives the highest reaction rate and the rate reaches 0.06 ${\mu}m$/min at $380^{\circ}C$ and ion-assisted etching dramatically enhances the surface reaction rate. With a negative 300 V DC bias voltage applied to the substrate, the surface reaction initiation temperature lowers and the rate increases about 20 times at $350^{\circ}C$ and up to 0.43 ${\mu}m$/min at $380^{\circ}C$, respectively. Surface morphology analysis confirms the etching rate measurements. Auger spectrum analysis clearly shows the adsorption of fluorine atoms on the reacted surface. From the current experimental findings and the results discussed in previous studies, mechanistic understanding of the surface reaction, fluorination and/or fluoro-carbonylation reaction, is provided.

• 한국음향학회지
• /
• 제1권1호
• /
• pp.37-44
• /
• 1982

In the mixed layer when the frequency approaches the cut-off frequency for the first mode of notmalmode theory, sound ceases to be trapped. Based on the data of surface sound velocities abtained during the period of 16 years in the Sea of Japan. A new cut-off frequency coefficient in the surface duct that will determine the miximum wave length for duct transimission of underwater sound has been calculated.

• 상하수도학회지
• /
• 제34권2호
• /
• pp.127-137
• /
• 2020

In this study, a MWCNT(multi-wall carbon nanotube) was added to polysulfone(PSf) support layer to improve flux of TFC(thin film composite) RO(reverse osmosis) membrane. Two different kinds of MWCNT were used. Surfaces of some MWCNTs were modified hydrophilically through acid treatment, while those of other MWCNTs were modified through heat treatment to maintain their hydrophobicity. MWCNT/PSf support layer was prepared by adding PSf to the NMP mixed solvent containing 0.1 wt% MWCNTs using a phase inversion method. The surface porosity of the MWCNT/PSf support increased by 42~46% while its surface pore size being maintained. The TFC RO membrane made of MWCNT/PSf support layer showed a 20% flux increase while its salt rejection characteristics is sustained. In addition, the MWCNT/PSf support layer has better mechanical stability than the PSf support layer, there resulting in an increased resistance of flux reduction due to physical pressure.

• 한국해양학회지:바다
• /
• 제12권4호
• /
• pp.280-286
• /
• 2007

동해 울릉분지에서 봄과 여름 동안 난수성 시계방향 와류가 영양염과 엽록소에 미치는 영향을 파악하기 위해서, 2005년 7월과 2006년 4월에 5개 정점에서 표층부터 수심 200 m까지 수온, 염분, 영양염, 엽록소 등을 관측하였다. 봄에는 와류 내부해역에서 표층 혼합층의 깊이가 150 m 이상으로 매우 깊은 반면, 외부해역에서는 $20{\sim}60$ m로 비교적 얕았다. 와류 내부해역에서 수직혼합이 활발히 일어나 표층해수에 영양염이 풍부한 반면, 외부해역에서는 표층에서 성층화가 생겨 심층에서 표층으로 영양염 공급이 충분하지 않아 농도가 낮았다. 봄에는 와류 내부해역에서 표층 혼합층 깊이가 유광층 깊이보다 훨씬 더 깊어서 엽록소 농도가 낮았으며, 와류 외부해역에서 측정한 총 엽록소(depth-integrated chlorophyll) 양은 내부해역에서 측정한 것보다 보다 두 배 이상 높았다. 여름에는 봄과 달리 모든 정점에서 표층 성층화가 강하게 발생하여, 영양염이 표층에서 완전히 고갈되었다. 여름에 관측한 엽록소는 모든 정점 수심 30 m 내외에서 최고 농도를 나타내어, 아표층 엽록소 최대(subsurface chlorophyll maximum)를 보였으며, 와류 내부해역에서 측정한 총 엽록소 양은 외부해역에서 측정한 것보다 두 배가량 높았다. 동해 울릉분지에서 거의 매해 나타나는 시계방향 와류는 식물플랑크톤 생물량에 매우 큰 영향을 미치는데, 그 영향이 봄과 여름에 다르게 나타났다; 봄에는 시계방향 와류가 식물플랑크톤 생물량을 제한하는 반면, 여름에는 반대로 식물플랑크톤 생물량을 증가시킨다.

• 한국전산유체공학회지
• /
• 제8권4호
• /
• pp.1-5
• /
• 2003

A Thin-layer Wavier-Stokes equations are applied for the hypersonic flow over blunt bodies with applications to laminar as well as turbulent flows. The equations are expressed in the forms of flux-vector splitting and explicit algorithm. The upwind schemes of Steger-Warming and Van Leer are investigated to predict accurately the heating loads along the surface of the body. A mixed scheme has been presented for the differencing the convective terms and the mixed scheme is found to be less dissipative producing accurate solutions.

• 한국정보통신학회논문지
• /
• 제19권5호
• /
• pp.1259-1268
• /
• 2015

음향층심도의 변화에 대한 이해는 해양상층에서 수중음향 통신, 음향 토모그레피 및 수중항체를 수색하거나 탐지하는 해군 작전에 많은 영향을 미친다. 일반적으로 음향층심도와 혼합층깊이의 정의는 다르게 내려져있으나 혼합층 깊이가 음향학적으로는 음향층심도와 같다고 할 수 있다. 본 연구에서는 동해에서 가용한 수온-염분 관측자료를 활용하여 연간 음향층심도와 혼합층깊이를 비교해 보았다. 비교를 위해 다양한 혼합층깊이 결정 기준과 방법으로부터 도출된 혼합층깊이 자료를 활용하였다. 분석결과 동해에서 음향층심도는 곡률변화를 이용한 혼합층깊이와 거의 유사하였으나 다른 혼합층깊이 기준을 적용하였을 시는 많은 차이를 보였다. 한편 음향층심도 계산의 정확도를 평가해 보기 위해 음파전달손실 모의 실험을 실시하였다. 이를 통해 음향층심도내에서 음파전달손실이 최소가 되는 최적주파수가 존재함을 확인하였다.