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.

Thermal Resistant Properties of Concrete with PCM/SiC-based Composite Aggregate on the High Temperature

Ryou, Jae Suk(류재석),Kim, Hong Gi(김홍기),Jeon, In Kyu(전인규) 한국콘크리트학회 2020 한국콘크리트학회 학술대회 논문집 Vol.32 No.1

Molecular Cloning and Hyperexpression of a Bt Gene, cryIAc, in Escherichia coli DH5α : Production and Usage of Anti-CryIAc Antibody

RYOU, CHONGSUK,CHUNG, TAEYOUNG,KWON, MOOSIK 한국미생물 · 생명공학회 2001 Journal of microbiology and biotechnology Vol.11 No.6

The gene coding for a Lepidoptera-specific insecticidal crystalline (or control) protein (ICP), recognized as cryLAc, from Bacillus thuringiensis subsp. kurstaki HD-73, was cloned into the vector pBluscript Ⅱ SK-, and then transformed in Escherichia coli DH5α. The clone was named EBtIAc and the chimeric phagemid, as pEBtIAc. Hyperexpression of CrylAc protoxin was observed in the extract of the culture of E. coli harboring pEBtIAc. Crystalline protoxin was purified by differential solubility. It was dissolved in alkaline pH, and exposed to trypsin to be activated. The molecular weights of the pro- and activated toxins on SDS-PAGE were estimated to be ca. 130 kDa and 60 kDa, respectively. The toxicity was tested by force-feeding larvae of gypsi moth (Lymantria dispar) with trypsinized protoxin. Using the batch of biologically active form of the toxin as an immunogen, anti-CrylAc antiserum was raised in a New Zealand white rabbit. Immunoglobulin G was fractionated from the serum by Protein-A sepharose affinity chromatography. Immunoreactivity of the antibody was examined by dot and Western blottings. It has been found that the anti-CryLAc antibody recognized the purified toxin at a level below a nanogram in terms of quantity. Using the antibody some of Bt-corns were able to be differentiated from tons of corn kernels which were imported from America as forage crops.

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>

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.

The Effects of Water Mist on the Compartment Fire

Ryou, Hong-Sun,Kim, Sung-Chan The Society of Air-Conditioning and Refrigerating 2004 International Journal Of Air-Conditioning and Refr Vol.12 No.1

The present study investigates the fire suppression characteristics using a water mist fire suppression system. Numerical simulations of fire suppression with water mist are performed with considering the interaction of fire plume and water spray. The predicted temperature fields of smoke layer are compared with those of measured data. Numerical results agree with the experimental results within $10^{\circ}C$ in the case without water mist. In the case of fire suppression with water mist, numerical results do not predict well for temperature field in the gradual cooling region after water mist injection. But the predicted results of initial fire suppression are in good agreement with those of measured data. The reason for the discrepancy between predicted and measured data is due to the poor combustion modeling during the injection of water mist. More elaborate models for numerical simulation are required for better predictions of the fire suppression characteristics using water mist.

Effect of Protease Inhibitors on Degradation of Recombinant Human Epidermal Growth Factor in Skin Tissue

Ryou, Hae-Won,Lee, Jang-Won,Yoon, Kyung Ae,Park, Eun-Seok,Chi, Sang-Cheol 성균관대학교 약학연구소 1996 成均藥硏論文集 Vol.8 No.1

Recombinant human epidermal growth factor (rhEGF), a polypeptide of 53 amino acid residues, is subject to degradation by numerous enzymes, expecially proteases, when it is applied on the skin for the treatment of open wound. Amastatin, aprotinin, bestatin, EDTA, EGTA, gabexate, gentamicin, leupeptin, and TPCK were investigated for the possible protease inhibitors, which may use to protect rhEGF from degradation by the enzymes in the skin, Skin homogenates containing protease inhibitors and rhEGF were incubated at 37℃ for 30 minutes. After the reaction was stopped with trifluoroacetic acid, the amount of rhEGF remaining in the sample was determined with an HPLC method. The percentages of rhEGF degraded, at the skin/PBs ratio of 0.25, in the mouse, rat, and human skin homogenate were 85%, 70%, and 46%, respectively. the degree of degradation of rhEGF in the cytosolic fraction was higher than that in the membrane fraction and these enzyme reactions were completed in 30 minutes. Bestatin, EGTA, and TPCK showed significant inhibitory effects on the degradation of rhEGF in the two fractions (p<0.05), while the other protease inhibitors had no significant inhibitory effect or, even resulted in deleterious effects. Therefore, the formulation containing one or several inhibitors among these effective inhibitors would be a promising topical preparation of rhEGF for the treatment of open wound.

Feasibility Assessment of Municipal Solid Waste Incineration Bottom Ash as Fine Aggregate of Cement Mortar

Ryou, Jae Suk(류재석),Jeon, In Kyu(전인규),Kim, Hong Gi(김홍기) 한국콘크리트학회 2020 한국콘크리트학회 학술대회 논문집 Vol.32 No.1