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.

A State Table Design for Load Balancing in distributed Computing System

Ryou, Jea-Cheol 충남대학교 자연과학연구소 1992 忠南科學硏究誌 Vol.19 No.1

분산시스템에서 부하균형이란 과부하상태인 프로세서로부터 부하가 적은 프로세서에게로 테스크들을 이동시킴으로써 평균응답시간을 줄일 수 있는 하나의 테스크 스케쥴링 방법이다. 테스크의 이동을 위해서는 각 프로세서의 부하상태에 대한 정보가 필요한데 분산시스템에서 정보를 얻는데 많은 메세지가 필요하게된다. 본 논문에서는 각 프로세서에게 송신집합을 부여하고 이 집합에 속해있는 프로세서에게만 부하정보를 보내는 방법을 사용한 결과, 부하정보를 얻는데 필요한 메세지 수가 줄어들게 되었다. 그러나 송신집합이 적절하게 선택되어야 하는데, 그렇지 않을 경우에는 일부의 프로세서간에는 서로의 부하정보를 알지못하여 부하균형이 이루어지지 않을 수가 있다. 또한 부적절한 송신집합은 특정 프로세서에게 부하균형 제어권을 주게되는 결과를 초래한다. 이에 본 논문에서는 어떤 프로세서간에도 부하균형이 이루어지며, 부하균형 제어권이 모든 프로세서에게 균등히 배분될 수 있는 송신집합을 구하여, 프로세서의 갯수가 N일때 메세지 수가 √N으로 줄어들 수 있음을 보였다. Load balancing is a task scheduling scheme for distributed computing system that transfers tasks from heavily-loaded processors to lightly-loaded or idle processors to balance workload so that average response time can be reduced. Maintaining workload information is needed in making task migration decisions. However, it may incur large message overhead. In this paper, we adapt a strategy that assigns a sending set to each processor so that load information of a processor is sent only to the processors in the sending set. Symmetrically, each processor receives load information only from a set of processors called receiving set. As a result, the size of load table can be reduced substantially. Maintaining a reduced load table requies fewer messages and less local processing time. However, sending set have to be chosen properly, otherwise load balancing may not occur between some pair of processors due to lack of load information in their load tables. Also, improper sending sets may put extra burden on some processors and leads to an uneven distribution of load balancing control. We propose an algorithm based on balanced sending sets with which load balancing can occur between any pair of processors and load balancing control is evenly distributed among participating processors. With balanced sending sets, number of messages required for each update can be reduced to the square root of the number of processors in the system. Evaluation of load balancing schemes with balanced sending sets is also presented in this paper.

Inhibition of xenograft tumor growth in mice by gold nanoparticle-assisted delivery of short hairpin RNAs against Mcl-1L

Ryou, S.M.,Park, M.,Kim, J.M.,Jeon, C.O.,Yun, C.H.,Han, S.H.,Kim, S.W.,Lee, Y.,Kim, S.,Han, M.S.,Bae, J.,Lee, K. Elsevier Science Publishers 2011 Journal of biotechnology Vol.156 No.2

A prerequisite for the therapeutic use of small RNAs is the development of a method that can deliver them into animals. Previous studies have shown the capability of functionalized gold nanoparticles to serve as a general platform for loading and delivering DNA oligonucleotides and short hairpin RNAs (shRNAs) into cultured human cells. Here, we report the ability of the gold nanoparticle-assisted gene delivery system (AuNP-GDS) to deliver shRNA to a xenograft tumor in a mouse model. AuNP-GDS delivery of in vitro synthesized shRNA targeted to the Mcl-1L gene knocked down levels of Mcl-1L mRNA and protein by ∼36% and ∼26%, respectively, which were sufficient to induce apoptosis of the xenograft tumor cells and consequently inhibited the development of the tumor. We demonstrated that our lego-like AuNP-GDS, which can easily load and deliver shRNAs targeted to any gene of interest into living systems, can deliver shRNAs into xenograft tumors, leading to antitumor activity in an animal model.

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

Ryou, Hae-Won,Lee, Jang-Won,Kyung, Kyung-Ae,Park, Eun-Seok,Chi, Sang-Cheol The Pharmaceutical Society of Korea 1997 Archives of Pharmacal Research Vol.20 No.1

Recombinant human epidermal growth factor (rhEGF), a polypeptide of 53 amino acid residues, is subject to degradation by numerous enzymes, especially 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 $37^{\circ}C$ 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 effects 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.

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>

Task Allocation in an N-Cube Multiprocessor System

Ryou, Jea-Cheol 충남대학교 자연과학연구소 1992 忠南科學硏究誌 Vol.19 No.2

하이퍼큐브 다중프로세서는 그들의 상호연결특징에 의하여 이상적인 병렬구조로 알려지고있다. 하이퍼큐브에서 하나의 테스크를 수행하기 위해서는 다중프로세서들 중에서 한 서브큐브에 테스크를 할당해야 하는데, 이러한 할당문제는 시스템성능에 중요한 영향을 미치고 있다. 본 논문에서는 테스크를 할당하기 위하여 하나의 서브큐브를 탐색하는 알고리즘을 제시하고자 한다. 전체 하이퍼큐브가 어느 테스크에게도 할당되지 않은 자유로운 상태라면, 어떤 크기의 서브큐브라도 쉽게 탐색할수 있지만, 일부의 프로세서가 어느 테스크에 할당이 되어 있으면 이러한 문제는 NP-Complete이다. 제시하고자하는 알고리즘의 기본방향은 일단 하이퍼큐브를 2차원의 격자구조로 변환하여 서브큐브를 이루는 프로세서들을 결정론적으로 탐색하는 것이다. 이 알고리즘이 지금까지 알려진 방법들보다 향상된 서브큐브 인지능력이 있음을 보였다. The n-dimensional hypercube multiprocessor is considered as ideal parallel architectures for their powerful interconnection features. A task arriving at a hypercube must be assigned to a subcube in the multiprocessor for execution. Efficient allocation of processors in a hypercube is a key to its performance and utilization. The purpose of this paper is to study how to find a free subcube to allocate an incoming task. When the entire hypercube is free, subcubes of arbitrary dimension can be imbedded in it. But if some processors have been assigned to other tasks, then the general mapping problem is NP-complete. The idea of the proposed algorithm is to map a hypercube to a two-dimensional grid structure and then deterministically find a set of free processor which form a subcube. We show that the proposed algorithm has enhanced subcube recognition capability than any existing algorithms.

Pulmonary Pneumatocele in a Pneumonia Patient Infected with Extended-Spectrum β-Lactamase Producing Proteus mirabilis

Ryou, Sung Hyeok,Bae, Jong Wook,Baek, Hyun Jin,Lee, Doo Hyuk,Lee, Sang Won,Choi, Gyu Ho,Han, Kyu Hyung,Kim, Se Weon,Kim, Hyunbeom,Hong, Goohyeon The Korean Academy of Tuberculosis and Respiratory 2015 Tuberculosis and Respiratory Diseases Vol.78 No.4

Pulmonary pneumatoceles are air-filled thin-walled spaces within the lung and are rare in adult cases of pneumonia. We report the case of a 74-year-old male who was admitted with a cough and sputum production. He had been treated with oral dexamethasone since a brain tumorectomy 6 months prior. Contrast-enhanced computed tomography (CT) of the chest revealed a large pneumatocele in the right middle lobe and peripheral pneumonic consolidation. Bronchoalveolar lavage was performed; cultures identified extended-spectrum ${\beta}$-lactamase (ESBL) producing Proteus mirabilis. A 4-week course of intravenous ertapenem was administered, and the pneumatocele with pneumonia resolved on follow-up chest CT. To the best of our knowledge, this is the first reported case of pulmonary pneumatocele caused by ESBL-producing P. mirabilis associated with pneumonia.

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>