UNVEILING THE STRUCTURE OF BARRED GALAXIES AT 3.6 μm WITH THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S⁴G). I. DISK BREAKS

Kim, Taehyun,Gadotti, Dimitri A.,Sheth, Kartik,Athanassoula, E.,Bosma, Albert,Lee, Myung Gyoon,Madore, Barry F.,Elmegreen, Bruce,Knapen, Johan H.,Zaritsky, Dennis,Ho, Luis C.,Comeró,n, Sé IOP Publishing 2014 The Astrophysical journal Vol.782 No.2

<P>We have performed two-dimensional multicomponent decomposition of 144 local barred spiral galaxies using 3.6 mu m images from the Spitzer Survey of Stellar Structure in Galaxies. Our model fit includes up to four components (bulge, disk, bar, and a point source) and, most importantly, takes into account disk breaks. We find that ignoring the disk break and using a single disk scale length in the model fit for Type II (down-bending) disk galaxies can lead to differences of 40% in the disk scale length, 10% in bulge-to-total luminosity ratio (B/T), and 25% in bar-to-total luminosity ratios. We find that for galaxies with B/T >= 0.1, the break radius to bar radius, r(br)/R-bar, varies between 1 and 3, but as a function of B/T the ratio remains roughly constant. This suggests that in bulge-dominated galaxies the disk break is likely related to the outer Lindblad resonance of the bar and thus moves outward as the bar grows. For galaxies with small bulges, B/T < 0.1, r(br)/R-bar spans a wide range from 1 to 6. This suggests that the mechanism that produces the break in these galaxies may be different from that in galaxies with more massive bulges. Consistent with previous studies, we conclude that disk breaks in galaxies with small bulges may originate from bar resonances that may be also coupled with the spiral arms, or be related to star formation thresholds.</P>

Lithium Dendrite Suppression with UV-Curable Polysilsesquioxane Separator Binders

Na, Wonjun,Lee, Albert S.,Lee, Jin Hong,Hwang, Seung Sang,Kim, Eunkyoung,Hong, Soon Man,Koo, Chong Min American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.20

<P>For the first time, an inorganic organic hybrid polymer binder was used for the coating of hybrid composites on separators to enhance thermal stability and to prevent formation of lithium dendrite in lithium metal batteries. The fabricated hybrid-composite-coated separators exhibited minimal thermal shrinkage compared with the previous composite separators (<5% change in dimension), maintenance of porosity (Gurley number 400 s/100 cm(3)), and high ionic conductivity (0.82 mS/cm). Lithium metal battery cell examinations with our hybrid-composite -coated separators revealed excellent C-rate and cyclability performance due to the prevention of lithium dendrite growth on the lithium anode even after 200 cycles under 0.2-5C (charge discharge) conditions. The mechanism for lithium dendrite prevention was attributed to exceptional nanoscale surface mechanical properties of the hybrid composite coating layer compared with the lithium metal anode, as the elastic modulus of the hybrid-composite-coated separator far exceeded those of both the lithium metal anode and the required threshold for lithium metal dendrite prevention.</P>

Intrinsic Flux Inequality in Forward Osmosis (FO) and Pressure-Retarded Osmosis (PRO) Processes

Albert S. Kim,이승원 한국막학회 2015 멤브레인 Vol.25 No.4

In pressure-retarded osmosis (PRO) and forward osmosis (FO) processes, solvent (permeate) flux depends on which surface the draw solution faces. There are two operation modes. PRO mode indicates that the active layer faces the draw solution, and FO mode means that the porous substrate fronts the draw stream. It is often observed that the PRO mode produces higher flux than that of FO under the same operating conditions. The current work uses the method of proof by contradiction, and mathematically proves the intrinsic flux inequality between the two modes.

Review of Basics Reverse Osmosis Process Modeling: A New Combined Fouling Index Proposed

Kim, Albert S. The Membrane Society of Korea 2017 멤브레인 Vol.27 No.4

해수담수화는 최근 전 세계적으로 대두되고 있는 물부족 현상을 해결하기 위한 최적 기술 중 하나이다. 막분리 및 투과 현상의 근본적인 이해는 차후의 막여과 기술의 발전을 위해서 뿐만 아니라, 현재 막기술 증진을 위한 통합적 디자인, 최적화 제어법, 그리고 중장기적 유지관리를 위해서도 매우 중요하다. 이에, 본 연구는 물질 전달 및 여과 현상에 대한 기존의 주요 모델들을 상세히 재검토하고, 통계물리학에 근간하여 주요 막분리 현상들을 이론적으로 분석하며, 원천적 모델에 기초한 물리적 의미와 그들이 실제 막공정에서 미치는 영향들에 대해서 함축적으로 토의하고자 한다. 이론적 재검토의 과정에서 새로이 유도된 복합적 막오염도(Combined Fouling Index (CFI))의 소개도 포함한다. Seawater desalination is currently considered to be one of the primary technologies to resolve the global water scarcity problem. A basic understanding of membrane filtration phenomena is significant not only for further technological development but also for integrated design, optimal control, and long-term maintenance. In this vein, the present work reviews the major transport and filtration models, specifically related to reverse osmosis phenomena, provides theoretical insights based on statistical mechanics, and discusses model-based physical meanings as related to their practical implications.

Membrane Distillation: Multi-scale and Multi-physics Phenomena

Albert S. Kim 대한환경공학회 2015 대한환경공학회 학술발표논문집 Vol.2015 No.10

Intrinsic Flux Inequality in Forward Osmosis (FO) and Pressure-Retarded Osmosis (PRO) Processes

Albert S. Kim,Seung-won Lee 한국막학회 2015 멤브레인 Vol.25 No.4

정삼투와 압력지연삼투 공정에서 용매의 투과율은 용매와 막이 접촉하는 방식에 의존한다. 각각의 공정에서 막의 활성층이 고농도 용매와 접촉하는 경우를 압력지연삼투 방식이라 하고, 고농도 용매가 막의 다공성 지지하층과 직면해 있는 경우를 정삼투 방식이라고 한다. 압력지연삼투 방식과 정삼투 방식은 각각 희석형 그리고 농축형의 내부농도 분극 현상을 유발하는데, 동일한 조작 조건에서 정삼투 방식보다 압력지연삼투 방식이 높은 투과율을 나타내는 현상이 실험적으로 관측되었다. 본고에서는 정삼투방식과 압력지연삼투 방식에서 발생하는 본질적인 투과율 불균형을 수학적 귀류법을 이용하여 증명하고, 물리적인 원인을 규명한다. In pressure-retarded osmosis (PRO) and forward osmosis (FO) processes, solvent (permeate) flux depends on which surface the draw solution faces. There are two operation modes. PRO mode indicates that the active layer faces the draw solution, and FO mode means that the porous substrate fronts the draw stream. It is often observed that the PRO mode produces higher flux than that of FO under the same operating conditions. The current work uses the method of proof by contradiction, and mathematically proves the intrinsic flux inequality between the two modes.

Computational Fluid Dynamics Simulation of Liquid-Cel Membrane using OpenFOAM

Albert S. Kim,Min Soo Park,Ji Hee Min 대한환경공학회 2015 대한환경공학회 학술발표논문집 Vol.2015 No.10

Review of Basics Reverse Osmosis Process Modeling: A New Combined Fouling Index Proposed

Albert S. Kim 한국막학회 2017 멤브레인 Vol.27 No.4

Seawater desalination is currently considered to be one of the primary technologies to resolve the global water scarcity problem. A basic understanding of membrane filtration phenomena is significant not only for further technological development but also for integrated design, optimal control, and long-term maintenance. In this vein, the present work reviews the major transport and filtration models, specifically related to reverse osmosis phenomena, provides theoretical insights based on statistical mechanics, and discusses model-based physical meanings as related to their practical implications.

역삼투 공정을 위한 모델링 총설 및 새로운 복합적 막오염도의 제안

Albert S. Kim 한국막학회 2017 멤브레인 Vol.27 No.4

해수담수화는 최근 전 세계적으로 대두되고 있는 물부족 현상을 해결하기 위한 최적 기술 중 하나이다. 막분리 및 투과 현상의 근본적인 이해는 차후의 막여과 기술의 발전을 위해서 뿐만 아니라, 현재 막기술 증진을 위한 통합적 디자인, 최적화 제어법, 그리고 중장기적 유지관리를 위해서도 매우 중요하다. 이에, 본 연구는 물질 전달 및 여과 현상에 대한 기존 의 주요 모델들을 상세히 재검토하고, 통계물리학에 근간하여 주요 막분리 현상들을 이론적으로 분석하며, 원천적 모델에 기 초한 물리적 의미와 그들이 실제 막공정에서 미치는 영향들에 대해서 함축적으로 토의하고자 한다. 이론적 재검토의 과정에 서 새로이 유도된 복합적 막오염도(Combined Fouling Index (CFI))의 소개도 포함한다. Seawater desalination is currently considered to be one of the primary technologies to resolve the global water scarcity problem. A basic understanding of membrane filtration phenomena is significant not only for further technological development but also for integrated design, optimal control, and long-term maintenance. In this vein, the present work reviews the major transport and filtration models, specifically related to reverse osmosis phenomena, provides theoretical insights based on statistical mechanics, and discusses model-based physical meanings as related to their practical implications.

Open cycle ocean thermal energy conversion using multiple condensers for selective power generation and seawater desalination

Albert Kim,H.J Kim(김현주),H.S Lee(이호생),S.W Cha(차상원) 한국해양환경·에너지학회 2014 한국해양환경공학회 학술대회논문집 Vol.2014 No.11

다단 응축기를 이용한 개방형 온도차발전 및 담수화사이클에 대한 기본 설계 및 해석 결과를 진행하였다. 저압 상태에서 증발기에서 증발된 증기는 터빈으로 유입되는 모드, 터빈 및 응축기로 유입되는 모드 및 응축기로 유입되는 모드로 나눌 수 있으며, 각 사이클에 대한 설계 및 해석 결과를 제공하고자 한다. Ocean Thermal Energy Conversion(OTEC) is a method that utilizes the natural temperature gradient that exists in tropical ocean between warm surface water and the deep sea water to generate electricity. When the temperature difference between surface seawater and deep seawater is over 20℃, the system can be run with much better efficiency. Researches for the cases of low temperature differences are also ongoing. As explained above, OC-OTEC uses very fundamental principles of thermal physics, however, its theoretical analysis and design details is significantly lacking in the literature. Optimization techniques were barely studied in terms of power generation and fresh water production. In this light, we proposed a conceptual design of a dual-use OC-OTEC plant applying fundamental issues of heat and mass transfer phenomena, as directly related to performance optimization.