충돌분무의 액적 거동에 미치는 비등방성 난류특성의 영향에 대한 수치해석 연구

고권현(G. H. Ko),유홍선(H. S. Ryou) 한국전산유체공학회 2003 한국전산유체공학회지 Vol.8 No.4

It is an aim of this study to perform extensive numerical study for analyzing the anisotropic turbulence effects on spatial and temporal behaviors of droplet for impinging sprays. The turbulence model of Durbin is used for comparisons with the k-E model. The turbulence-induced dispersions of droplets are consider to describe the anisotropy of turbulence effectively and spray/wall interactions are simulated using the model of Lee and Ryou. Present study investigates the overall and the internal structures of impinging diesel sprays such as spray shapes, radius and height of wall sprays, Sauter mean diameter (SMD), local droplet velocity, and local gas velocity and compared the results with experimental data by two adopted turbulence models. When the anisotropy effect of turbulence is included, better predictions for both gas and droplet tangential velocities are obtained, compared to the k-ε model. It is concluded that anisotropic effect of turbulence should be considered for simulating impinging diesel sprays.

Host People's Kindness and Migrant Workers' Cultural Adaptation: Evidence from South Korea

Jihyun Ryou(Jihyun Ryou),Sang-Yeon Kim(Sang-Yeon Kim) 한국학술연구원 2022 Korea Observer Vol.53 No.4

This study purports to determine the predictors of migrant workers' cultural adaptation in South Korea. In the main, we examined the extent to which the level of inter-/intracultural socializing, exposure to local/native media, and host culture receptivity affect the level of cultural adaptation in cognitive, affective, behavioral domains. Potential impacts of demographic factors (e.g., age, sex, ethnicity, marital status, living alone vs. with family, education level, residency in years, perceived cultural similarity) were also explored. To find answers to the research questions, a total of 634 migrant workers from 37 different nations were reached using a snowball sampling. Surveys were collected in 12 districts of Seoul, the capital of South Korea, and 21 adjacent metropolitan areas. Results indicate that intercultural interaction with host people and media exposure to local contents tend to help improve their knowledge about South Korea (e.g., language, culture). With all else equal, migrant workers treated kindly by Koreans at the workplace and in service sectors, and those living with family, compared to those who live alone, tended to enjoy a greater satisfaction with work and life in South Korea and were more willing to stay. Practical implications for Korean policymakers include encouraging competent migrant workers to move together with the family, making administrative efforts to further simplify the documentation process, and initiating public campaigns to raise host culture receptivity among Korean citizens.

Development and Application of a New Spray Impingement Model Considering Film Formation in a Diesel Engine

Ryou, Hong-Sun,Lee, Seong-Hyuk,Ko, Gwon-Hyun,Hong, Ki-Bae The Korean Society of Mechanical Engineers 2001 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.15 No.7

The present article presents an extension to the computational model for spray/wall interaction and liquid film processes that has been dealt with in the earlier studies (Lee and Ryou, 2000a). The extensions incorporate film spread due to impingement forces and dynamic motion induced by film inertia to predict the dynamic characteristics of wall films effectively. The film model includes the impingement pressure of droplets, tangential momentum transfer due to the impinging droplets on the film surface and the gas shear force at the film surface. Validation of the spray/wall interaction model and the film model was carried out for non-evaporative diesel sprays against several sources of experimental data. The computational model for spray/wall interactions was in good agreement with experimental data for both spray radius and height. The film model in the present work was better than the previous static film model, indicating that the dynamic effects of film motion should be considered for wall films. On the overall the present film model was acceptable for predication of the film radius and thickness.

Low temperature NO adsorption over hydrothermally aged Pd/CeO₂ for cold start application

Ryou, YoungSeok,Lee, Jaeha,Lee, Hyokyoung,Kim, Chang Hwan,Kim, Do Heui Elsevier 2018 CATALYSIS TODAY - Vol.307 No.-

<P><B>Abstract</B></P> <P>Pd/CeO<SUB>2</SUB> catalyst hydrothermally aged at 750°C for 25h was employed for NO adsorption at low temperature (80–160°C). For comparison, Pt or Pt-Pd supported on CeO<SUB>2</SUB> or Al<SUB>2</SUB>O<SUB>3</SUB> catalysts were also applied. Analysis of the hydrothermally aged catalysts clearly indicates that PGM (Pt and/or Pd) on CeO<SUB>2</SUB> is more resistant to sintering than that on Al<SUB>2</SUB>O<SUB>3</SUB> support. Reducibility test of Pd/CeO<SUB>2</SUB> by H<SUB>2</SUB>-TPR exhibits H<SUB>2</SUB> spillover from Pd to CeO<SUB>2</SUB> support, attributed to the strong interaction between Pd and CeO<SUB>2</SUB>. NO adsorption/desorption results demonstrate that CeO<SUB>2</SUB>-based catalysts exhibit superior NO adsorption ability than Al<SUB>2</SUB>O<SUB>3</SUB>-based catalysts. In addition, PGM/CeO<SUB>2</SUB> catalysts shows the desirable desorption temperature for cold start application. The influence of reactant in stream, NO adsorption time, and temperature on low temperature NO adsorption over Pd/CeO<SUB>2</SUB> is also examined to advance the understanding of NO adsorption/desorption behavior. DRIFT results of adsorbed NO<SUB>x</SUB> species on Pd/CeO<SUB>2</SUB> during NO adsorption/desorption prove that NO<SUB>x</SUB> desorption peaks at 250, 300, and 450°C originate from weakly bound nitrite, nitro-nitrito species, and nitrate species, respectively. In Pd/CeO<SUB>2</SUB> catalyst, Pd plays a role in providing additional NO adsorption site arising from the intimate interaction between Pd and CeO<SUB>2</SUB> and promoting the oxidation from adsorbed nitrite to nitrate. It can be summarized that Pd/CeO<SUB>2</SUB> can be a good candidate as low temperature NO adsorption catalyst for cold start application.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PGM on CeO<SUB>2</SUB> is more stable than that on Al<SUB>2</SUB>O<SUB>3</SUB> after hydrothermal treatment. </LI> <LI> CeO<SUB>2</SUB>-based catalyst has better NO adsorption ability than Al<SUB>2</SUB>O<SUB>3</SUB>-based catalysts. </LI> <LI> Pd improves NO adsorption ability of CeO<SUB>2</SUB> by promoting oxidation of NO<SUB>x</SUB> on CeO<SUB>2</SUB>. </LI> <LI> Pd on CeO<SUB>2</SUB> activates new NO adsorption sites which desorb NO at around 300°C. </LI> <LI> Pd/CeO<SUB>2</SUB> has highest NO adsorption capacity and desirable desorption temperature. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Numerical Evaluation of Crashworthiness of Automotive Sheets

Ryou, Han Sun,Lee, Myoung Gyu,Kim, Chong Min,Chung, Kwan Soo Trans Tech Publications, Ltd. 2007 Key Engineering Materials Vol.345-346 No.-

<P>Crash simulations were performed for automotive sheets. To understand the influence of crystal structures in sheet materials on crashworthiness, the effect of the yield function shape was studied by adopting the recently developed non-quadratic anisotropic yield surface, Yld2004-18p. The effect of the back-stress was also investigated by comparing simulation results obtained for the isotropic, kinematic and combined isotropic-kinematic hardening laws based on the modified Chaboche model. In addition, the effects of anisotropy and sheet thickness on crashworthiness were evaluated.</P>

A Gene Mutation of Human Dihydrolipoamide Dehydrogenase cDNA

Ryou, Chongsuk,Kwon, Moosik 성균관대학교 생명공학연구소 1999 生命工學硏究 Vol.5 No.1

Mammalian pyruvate dehydrogenase complex (PDC) catalyzes oxidative decarboxylation of pyruvate to produce Co2, acetyl-CoA, and NADH. Dihydrolipoamide Dehydrogenase (E3) is a component of the complex, and the enzymatic deficiency leads to lactic acidosis, increased concentrations of branched-chain amino acids in the plasma and increased urinary excretion of alpha-keto acids. The E3 deficiency also causes neurological degeneration due to the sensitivity of the central nervous system to defects in oxidative metabolism. In this study, an E3 mutant cDNA was generated from a patient showing some pyruvate metabolic defect. The mutant cDNA was subcloned into pBluescript SK-, and nested deletion set of the clone were prepared for the analysis of the whole nucleotide sequence. A silent mutation found in the clone meaning that there was no changes in amino acid sequence.

Enhancement of Cycle Performance of Lithium Secondary Batteries Based on Nano-Composite Coated PVdF Membrane

Ryou, Myung-Hyun,Han, Young-Dal,Lee, Je-Nam,Lee, Dong-Jin,Park, Jung-Ki The Korean Electrochemical Society 2008 한국전기화학회지 Vol.11 No.3

The multilayered membrane for lithium rechargeable batteries based on poly (vinylidene fluoride) (PVdF) is prepared with the coated layer containing nano-sized filler. The prepared membranes were subjected to studies of mechanical strength, morphology, interfacial stability, impedance spectroscopy, ionic conductivity, and cycle performance. The localized inorganic filler in the PVdF composite membrane rendered mechanical strength much reduced because of its low stretching ratio and it results in around half value of the mechanical strength of highly stretched PVdF membrane. In order to achieve high ionic conductivity and interfacial stability without sacrificing high mechanical strength, coating layer with nano-filler was newly introduced to PVdF membrane. The ionic conductivity of the coated membrane was 1.03 mS/cm, and the interface between the coating layer and PVdF membrane was stable when the membrane was immersed into liquid electrolyte. The discharge capacity of the cell based on nano-filler coated PVdF membrane was around 91% of the initial discharge capacity after 250 cycles, which is an improvement in cycle performance compared to the case for the non-coated PVdF membrane.

Shiga-like toxin-based high-efficiency and receptor-specific intracellular delivery system for a protein

Ryou, Jeong-Hyun,Sohn, Yoo-Kyoung,Hwang, Da-Eun,Kim, Hak-Sung Elsevier 2015 Biochemical and biophysical research communication Vol.464 No.4

<P><B>Abstract</B></P> <P>The cell-specific cytosolic delivery of functional macromolecules with high efficiency is of great significance in molecular medicine and biotechnology. Herein, we present a Shiga-like toxin II-based high-efficiency and receptor-specific intracellular delivery system. We designed and constructed the Shiga-like toxin-based carrier (STC) to comprise the targeting and translocation domains, and used it for delivering a protein cargo. The STC was shown to deliver a protein cargo into the cytosol with high efficiency in a receptor-specific manner, exhibiting much higher efficiency than the most widely used cell-penetrating peptide. The general utility of the STC was demonstrated by modulating the targeting domain. The present delivery platform can be widely used for the intracellular delivery of diverse biomolecules in a receptor-specific and genetically encodable manner.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We present a highly efficient and cell-specific intracellular delivery system. </LI> <LI> Shiga-like toxin-based carrier comprises the targeting and translocation domain. </LI> <LI> EGFP was successfully delivered into the cytoplasm of mammalian cells. </LI> <LI> The receptor-specificity was changed by modulating the targeting domain. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Lithium-Ion Batteries: Excellent Cycle Life of Lithium-Metal Anodes in Lithium-Ion Batteries with Mussel-Inspired Polydopamine-Coated Separators (Adv. Energy Mater. 6/2012)

Ryou, Myung-Hyun,Lee, Dong Jin,Lee, Je-Nam,Lee, Yong Min,Park, Jung-Ki,Choi, Jang Wook Wiley (John WileySons) 2012 ADVANCED ENERGY MATERIALS Vol.2 No.6

Drawing the Line

Ryou Kyongjoo H. 숙명여자대학교 아세아여성문제연구소 1999 Asian Women Vol.8 No.-

Characters S: An artist/illustrator, around 30, shortish, well-mannered M: S's separated wife, near 40 Ss: S's sister, in her late 20s, a writer An unidentified Voice Willard: S's agent (never appears on the scene) Guapa: S's Golden retriever kay: Willard's secretary