Linear and non-linear analyses on the onset of miscible viscous fingering in a porous medium

류원선,김민찬 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.7

The onset of miscible viscous fingering in porous media was analyzed theoretically. The linear stability equations were derived in the self-similar domain, and solved through the modal and non-modal analyses. In the nonmodal analysis, adjoint equations were derived using the Lagrangian multiplier technique. Through the non-modal analysis, we show that initially the system is unconditionally stable even in the unfavorable viscosity distribution, and there exists the most unstable initial disturbance. To relate the theoretical predictions with the experimental work, nonlinear direct numerical simulations were also conducted. The present stability condition explains the system more reasonably than the previous results based on the conventional quasi-steady state approximation.

등가회로모델을 이용한 역전기투석 스택전지의 성능에 대한 수치모사

류원선,유진수 한국막학회 2017 한국막학회 총회 및 학술발표회 Vol.2017 No.11

역전기투석전지는 염수-기수의 농도차이를 원동력으로 이온교환막의 선택성에 의해 양이온과 음이온을 서로 반대방향으로 이동시켜 전력을 생산한다. 이상적인 이온교환막의 경우 35 g/L과 0.5 g/L 농도의 염수와 기수를 흘려 보냈을 때, 약 0.1 V의 전압 출력을 가진다. 본 연구에서는 역전기투석 스택전지의 출력특성에 영향을 주는 인자로서 막저항, 염수와 기수의 전기전도도, 막 이동수, 막 면적, 유로 두께 및 메쉬의 개방면적비, 스택수 등을 고려하여 수치모사를 수행하였다. 스택전지 내 유로에서 발생하는 누설전류 및 내부저항을 고려한 등 가회로모델을 수립하였고, 상용 이온교환막으로 제작된 스택전지 실험결과로부터 개방전압, 단락전류밀도, 최대전력밀도와 같은 중요 전지특성에 대하여 수치 모사의 정합성을 확인하였다.

Effect of vertically varying permeability on the onset of convection in a porous medium

류원선,김민찬 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.6

Considering the vertically varying permeability of a porous medium, we conducted theoretical and numerical analyses on the onset of buoyancy-driven instability in an initially quiescent, fluid-saturated, horizontal porous layer. Darcy’s law was employed to explain the fluid flow through a porous medium and linear and nonlinear analyses are conducted. In the semi-infinite domain, the growth of disturbance and the onset of convection were analyzed with and without the quasi-steady state approximation. The present analysis of initial growth rate shows that the system is initially unconditionally stable regardless of a vertical heterogeneity parameter. The onset conditions of buoyancydriven instabilities were investigated as a function of the Darcy-Rayleigh number and the heterogeneity parameter. To find the effect of a vertical heterogeneity on the flow after the onset of convection, nonlinear numerical simulations also were conducted using the result of the linear analysis as a starting point. Nonlinear numerical simulations show that the finger-like instability motion is not readily observable at a critical time and it becomes visible approximately when a mass transfer rate substantially increases.

섭취를 통한 급성중독으로 단일기관 응급실을방문한 소아환자의 나이대별 특성

류원선,최재연,조진성,임용수,현성열,양혁준 대한소아응급의학회 2018 대한소아응급의학회지 Vol.5 No.1

Purpose: To investigate the age group characteristics of children who visited the emergency department with acute poisoning by ingestion. Methods: We reviewed children under 19 years who visited the emergency department for acute poisoning by ingestion from 2012 to 2017. The children were divided into 3 age groups; infants (0-1 years), preschoolers (2-5 years), and schoolers (6-18 years). Clinical characteristics, intentional ingestion, involved substances (drugs, household products, artificial substances, and pesticides), decontamination and antidote therapy, and outcomes of the 3 age groups were compared. We also performed multivariable logistic regression analysis to identify factors associated with hospitalization. Results: A total of 622 children with acute poisoning by ingestion were analyzed. Their annual proportions to overall pediatric emergency patients ranged from 0.3% to 0.4%. Age distribution showed bimodal peaks at 0-2 years and 15-17 years. The infants showed lower frequency of girls, intentional ingestion, ingestion of drugs, performance of decontamination and antidote therapy, and hospitalization than 2 older groups (P < 0.001). Most decontamination, antidote therapy, and hospitalization occurred in the schoolers (P < 0.001). The most frequently reported substances were household cleaning substances in the infants (18.2%), antihistamines in the preschoolers (15.8%), and analgesics in the schoolers (37.5%). The factors associated with hospitalization were intentional ingestion (adjusted odds ratio [aOR], 7.08; 95% confidence interval [CI], 2.85-17.61; P = 0.001) and schoolers (aOR, 2.33; 95% CI, 1.10-7.53; P = 0.031; compared with infants). Only 1 in-hospital mortality was found in a boy aged 2 years who ingested methomyl. Conclusion: Infants may experience non-intentional ingestion, ingestion of non-pharmacologic substances (especially household cleaning substances), discharge without decontamination and antidote therapy more frequently than older children. Thus, we need age group-specific, preventive and therapeutic plans for children with acute poisoning.

행사보고 : “2011년 제7회 대학생 화학공학 창의설계 경진대회”를 마치며

류원선 한국화학공학회 2011 NICE Vol.29 No.6

IF-Steel의 ECAP 공정 중 채널 상태와 온도에 따른 마찰효과

류원선(W. S. Ryu),서민홍(M. H. Seo),김형섭(H. S. Kim),백승철(S. C. Baik),Rahph Hellming,Yuri Estrin 한국소성가공학회 2003 한국소성가공학회 학술대회 논문집 Vol.2003 No.10

전기영동법으로 알루미늄에 침적된 영가 철 나노입자에 의한 질산성 질소의 환원

류원선(Won Ryoo) 한국청정기술학회 2009 청정기술 Vol.15 No.3

최근 주요 수질오염 물질로 대두되고 있는 질산성 질소의 제거를 목적으로 영가 철 나노입자에 의한 질산성 질소의 환원반응성을 평가하였다. 영가 철 나노입자의 제조방법에 따른 반응성 차이를 규명하기 위해 유기용매 상에 계면활성제를 첨가하여 나노미터 크기 수준의 수용액 분산상에서 입자를 합성하는 마이크로에멀젼 방법과, 수용액 상의 철 이온을 환원시켜 입자를 합성하는 두 가지 방법으로 영가 철 나노입자를 합성하였다. 또한 전기영동법으로 알루미늄에 침적시킨 영가 철 나노입자에 의한 질산성 질소 제거속도를 측정하고, 고정화되지 않은 나노 철 입자에 의한 반응속도와 비교하였다. 환원반응을 질산성 질소에 대한 1차 반응으로 가정하여 수용액 방법 및 마이크로에멀젼 방법으로 제조된 영가 철 나노입자의 반응성을 평가한 결과, 반응 속도상수는 각각 1.40×10?² min?¹ 와 3.49×10?² min?¹ 로서 비표면적에 비례하여 증가하였다. 알루미늄에 침적된 나노입자는 현탁된 나노입자의 반응과 비교하여 약 30% 감소된 반응속도를 보였으나, 과량의 질산성 질소가 존재하는 경우 나노 철의 단위 질량당 질산성 질소의 제거효율 면에서 더 우수한 특성을 보였다. 나노철 입자의 현탁액은 반응시간 30분 이내에 반응속도가 감소하는 경향을 보였으나, 알루미늄에 침적된 나노철 입자는 3시간 이상 활성을 유지하였으며, 최종 생성물로 기체 질소를 발생시키는 것을 확인하였다. Reductive reactivity of zero-valent iron nanoparticles was investigated for removal of nitratenitrogen which is considered one of the major water pollutants. To elucidate the difference in reactivity between preparation methods, iron nanoparticles were synthesized respectively from microemulsion and aqueous solution of ferric ions. Iron nanoparticles prepared from microemulsion were deposited on aluminum by electrophoretic method, and their reaction kinetics was compared to that of the same nanoparticles suspended in aqueous batch reaction. With an approximation of pseudo-first-order reaction, rate constants for suspended nanoparticles prepared from microemulsion and dilute aqueous solution were 3.49×10?² min?¹ and 1.40×10?² min?¹, respectively. Iron nanoparticles supported on aluminum showed ca. 30% less reaction rate in comparison with the identical nanoparticles in suspended state. However, supported nanoparticles showed the superior effectiveness in terms of nitrate-nitrogen removal per zero-valent iron input especially when excess amounts of nitrates were present. Iron nanoparticles deposited on aluminum maintained reductive reactivity for more than 3 hours, and produced nitrogen gas as a final reduction product of nitrate-nitrogen.

The Bcl-2/Bcl-xL Inhibitor ABT-263 Attenuates Retinal Degeneration by Selectively Inducing Apoptosis in Senescent Retinal Pigment Epithelial Cells

정혜원,류원선,Chul-Woo Park,Junghoon Kim,Hyungwoo Lee 한국분자세포생물학회 2023 Molecules and cells Vol.46 No.7

Age-related macular degeneration (AMD) is one of the leading causes of blindness in elderly individuals. However, the currently used intravitreal injections of anti-vascular endothelial growth factor are invasive, and repetitive injections are also accompanied by a risk of intraocular infection. The pathogenic mechanism of AMD is still not completely understood, but a multifactorial mechanism that combines genetic predisposition and environmental factors, including cellular senescence, has been suggested. Cellular senescence refers to the accumulation of cells that stop dividing due to the presence of free radicals and DNA damage. Characteristics of senescent cells include nuclear hypertrophy, increased levels of cell cycle inhibitors such as p16 and p21, and resistance to apoptosis. Senolytic drugs remove senescent cells by targeting the main characteristics of these cells. One of the senolytic drugs, ABT-263, which inhibits the antiapoptotic functions of Bcl-2 and Bcl-xL, may be a new treatment for AMD patients because it targets senescent retinal pigment epithelium (RPE) cells. We proved that it selectively kills doxorubicin (Dox)-induced senescent ARPE-19 cells by activating apoptosis. By removing senescent cells, the expression of inflammatory cytokines was reduced, and the proliferation of the remaining cells was increased. When ABT-263 was orally administered to the mouse model of senescent RPE cells induced by Dox, we confirmed that senescent RPE cells were selectively removed and retinal degeneration was alleviated. Therefore, we suggest that ABT-263, which removes senescent RPE cells through its senolytic effect, has the potential to be the first orally administered senolytic drug for the treatment of AMD.

표면 전하를 갖는 나노기공을 통한 이온 이동현상 수치해석

유진수,류원선 한국막학회 2019 한국막학회 총회 및 학술발표회 Vol.2019 No.11

CAD/CAE 통합을 위한 구조설계 최적화에 관한 연구

박창규,양영순,류원선,장범선,Park, Chang-Kue,Yang, Young-Soon,Ruy, Won-Son,Jang, Beom-Seon 한국전산구조공학회 2009 한국전산구조공학회논문집 Vol.22 No.2

개발단계에 있어서 필수적인 성계 프로세스인 CAD 및 CAE 시스템은 각각 개별적으로 발전되어 왔다. 더구나 제품개발에 있어서 부서나 기업간의 CAD 또는 CAE 시스템의 이질성이나 제품 데이터 표현방법의 차이로 인해 이를 통합하기 위한 부가적인 비용과 개발기간이 발생하기도 한다. 따라서 설계과정에서의 협업을 성공적으로 수행하기 위해서는 제품 개발 초기 단계에서부터 이질적인 CAD와 CAE 등의 관련 시스템을 유기적으로 통합 관리할 수 있어야 한다. 따라서 본 연구에서는 보다 효과적으로 통합관리하고 설계 및 해석도구들의 연계사용을 지원하기 위해 최적설계를 포함한 설계 및 해서시스템을 통합화하는 기법을 제안하고, 보강판 예제를 통해 CATIA를 이용한 CAD와 CAE간의 데이터 전환의 문제점을 극복하는 것을 보여줌으로서 이 기법의 타당성을 보여주고자 한다. 이와 아울러 최적화 과정을 수행함에 있어서 CAE 프로세스는 구조 최적화 과정에 있어서 하나의 필수적인 부분임을 확인할 수 있었다. In product development, CAD and CAE systems taking part in the design process were individually developed. Furthermore, in product development, different divisions and businesses often have heterogeneous CAD/CAE systems and methods for expressing product data, and addressing this heterogeneity creates additional costs and causes longer development periods. To ensure successful collaboration in the design process, it is therefore imperative that different CAD, CAE, and other related systems be managed in an organic and integrated manner from the initial stages of product development. Therefore, this study suggests an integrated CAD/CAE system including optimization in a more effective and integrated manner but also to support interfacing and the collective use of design and analysis tools. To validate the proposed method, a stiffened plate example is taken as an example. It is found that the proposed method could overcome the bottleneck of CAD and CAE such as transferability of data, though CATIA and ANSYS are used at the moment. Besides, carrying out an optimization process during the CAE process is another essential parts for the structural optimization process.