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121 results on '"Kim, Yong W."'

1. Entropy production and fluctuation theorems on complex networks

Author

Jung, Jaewoo, Um, Jaegon, Lee, Deokjae, Kim, Yong W., Lee, D. Y., Pak, H. K., and Kahng, B.

Subjects
Condensed Matter - Statistical Mechanics
Abstract

Entropy production (EP) is known as a fundamental quantity for measuring the irreversibility of processes in thermal equilibrium and states far from equilibrium. In stochastic thermodynamics, the EP becomes more visible in terms of the probability density functions of the trajectories of a particle in the state space. Inspired by a previous result that complex networks can serve as state spaces, we consider a data packet transport problem on complex networks. Entropy is produced owing to the complexity of pathways as the packet travels back and forth between two nodes. The EPs are exactly enumerated along the shortest paths between every pair of nodes, and the functional form of the EP distribution is determined by extreme value analysis. The asymptote of the accumulated EP distribution is found to follow the Gumbel distribution.

Published
2019
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2. Numerical modeling of hot gas ingestion into the rotor-stator disk cavities of a subscale 1.5-stage axial gas turbine

Author

Ghasemian, Masoud, Princevac, Marko, Kim, Yong W, and Hamm, Hans D

Subjects
Computational Fluid Dynamic, Gas turbine, Ingestion, Turbulence modeling, Rotor-stator disk cavity, Mathematical Sciences, Physical Sciences, Engineering, Mechanical Engineering & Transports
Abstract

Both steady and unsteady Reynolds Averaged Navier-Stokes (RANS) techniques coupled with the k-ε and k-ω(SST) turbulence models are utilized to study the flow characteristics and hot gas ingestion through rim seal in a subscale 1.5-stage axial gas turbine. A scalar transport equation is solved for a tracer gas to represent the coolant flow interaction with the main stream flow. To validate the numerical methodology, radial pressure and sealing effectiveness distributions are compared with the experimental data. The k-ω(SST) turbulence model has the capability to predict secondary flow characteristics, reattachment and separation, thus leading to better agreement with the experimental data. Both radial and circumferential pressure distributions are analyzed to get deeper insight into rotationally and externally induced ingress mechanisms. The circumferential pressure peak-to-trough amplitude is significantly attenuated in the cavity region compared to annulus region. Finally, different purge flow rates and rotational speeds are examined. Results indicate that as purge flow rate increases, the static pressure in the disk cavity region raises remarkably and consequently the sealing effectiveness improves. Averaged sealing effectiveness in the rim cavity decreases linearly with the rotational speed. To visualize different mechanisms of ingestion, streamline and flow field are shown.

Published
2019

9. Structural Disorder as Control of Transport Properties in Metallic Alloys

Author

Kim, Yong W and Kaiser, Eric

Subjects
Technology & Engineering / Materials Science
Abstract

Structural disorder is ubiquitous for a large class of metallic alloys. Such an alloy’s transport properties are highly susceptible to change when the disorder is modified. A first-principle method has been developed for modeling of disorders in metallic alloys. In this approach, an alloy specimen is regarded as a randomly close-packed mixture of a population of nanocrystallites and constituent atoms in glassy state. The disorder is then represented by the size distribution function of the nanocrystallites. Under sustained exposure to thermal, stress, nuclear or chemical forcing at an elevated temperature, the distribution function becomes modified, and this process is predictable for a given forcing condition, and thus controllable. Transport of excitations is affected by the detail of the distribution function, making it possible to control transport properties, all at a fixed alloy composition. The modeling and experimental support will be presented.

Published
2022

28. Transdifferentiation-inducing HCCR-1 oncogene

Author

Kim Jin, Park Yong G, Kim Dong W, Jeun Shin S, Chung Yeun J, Kim Tae E, Kim Yong W, Hur Soo Y, Lee Youn S, Shin Seung M, Kim SangHee, Yoo JinAh, Kim Hyun K, Ha Seon-Ah, Shin Soon Y, Lee Young H, and Kim Jin W

Subjects
Cytology, QH573-671
Abstract

Abstract Background Cell transdifferentiation is characterized by loss of some phenotypes along with acquisition of new phenotypes in differentiated cells. The differentiated state of a given cell is not irreversible. It depends on the up- and downregulation exerted by specific molecules. Results We report here that HCCR-1, previously shown to play an oncogenic role in human cancers, induces epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) in human and mouse, respectively. The stem cell factor receptor CD117/c-Kit was induced in this transdifferentiated (EMT) sarcoma tissues. This MET occurring in HCCR-1 transfected cells is reminiscent of the transdifferentiation process during nephrogenesis. Indeed, expression of HCCR-1 was observed during the embryonic development of the kidney. This suggests that HCCR-1 might be involved in the transdifferentiation process of cancer stem cell. Conclusions Therefore, we propose that HCCR-1 may be a regulatory factor that stimulates morphogenesis of epithelia or mesenchyme during neoplastic transformation.

Published
2010
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31. Real-time measurement of materials properties at high temperatures by laser produced plasmas

Author

Kim, Yong W

Subjects
Materials Processing
Abstract

Determination of elemental composition and thermophysical properties of materials at high temperatures, as visualized in the context of containerless materials processing in a microgravity environment, presents a variety of unusual requirements owing to the thermal hazards and interferences from electromagnetic control fields. In addition, such information is intended for process control applications and thus the measurements must be real time in nature. A new technique is described which was developed for real time, in-situ determination of the elemental composition of molten metallic alloys such as specialty steel. The technique is based on time-resolved spectroscopy of a laser produced plasma (LPP) plume resulting from the interaction of a giant laser pulse with a material target. The sensitivity and precision were demonstrated to be comparable to, or better than, the conventional methods of analysis which are applicable only to post-mortem specimens sampled from a molten metal pool. The LPP technique can be applied widely to other materials composition analysis applications. The LPP technique is extremely information rich and therefore provides opportunities for extracting other physical properties in addition to the materials composition. The case in point is that it is possible to determine thermophysical properties of the target materials at high temperatures by monitoring generation and transport of acoustic pulses as well as a number of other fluid-dynamic processes triggered by the LPP event. By manipulation of the scaling properties of the laser-matter interaction, many different kinds of flow events, ranging from shock waves to surface waves to flow induced instabilities, can be generated in a controllable manner. Time-resolved detection of these events can lead to such thermophysical quantities as volume and shear viscosities, thermal conductivity, specific heat, mass density, and others.

Published
1990

32. Combined Analysis of AFP and HCCR-1 as an Useful Serological Marker for Small Hepatocellular Carcinoma: A Prospective Cohort Study

Author

Zhang, Guoxin, Ha, Seon-Ah, Kim, Hyun K., Yoo, Jinah, Kim, Sanghee, Lee, Youn S., Hur, Soo Y., Kim, Yong W., Kim, Tae E., Park, Yong G., Wang, Jing, Yang, Yang, Xu, Zekuan, Song, Eun Y., Huang, Zuhu, Jirun, Peng, Zhongtian, Jin, Shishi, Qiao, Zhuqingqing, Cui, Lei, Gong, and Kim, Jin W.

Subjects
Adult, Male, Carcinoma, Hepatocellular, Hepatocellular carcinoma, AFP, Clinical Biochemistry, Proto-Oncogene Mas, HCCR-1, Proto-Oncogene Proteins, Biomarkers, Tumor, Genetics, Humans, Prospective Studies, Molecular Biology, neoplasms, Early Detection of Cancer, Aged, lcsh:R5-920, Liver Neoplasms, Biochemistry (medical), General Medicine, Middle Aged, digestive system diseases, Tumor Burden, ROC Curve, biomarker, Female, Other, alpha-Fetoproteins, lcsh:Medicine (General)
Abstract

Hepatocellular carcinoma (HCC) is one of the most frequent malignant tumors in the world. The only serological marker widely used for the diagnosis of HCC is alpha-fetoprotein (AFP). Despite that AFP is widely used for the diagnosis of HCC, it has a limit as a serological marker due to its low sensitivity and specificity. The human cervical cancer proto-oncogene 1 (HCCR-1) was previously reported as a new biomarker for HCC. To further evaluate the HCCR-1 as a biomarker for HCC, we conducted the prospective cohort study. We evaluated the significance of simultaneous measurement of 2 tumor markers in the diagnosis of HCC in China, Japan and Korea. Two markers for HCC, AFP and HCCR-1, were measured in the sera obtained from 1,338 patients at the time of initial diagnosis of HCC. Of the 1338 HCC patients, 616 (46%) and 686 (51.3%) were sero-positive for AFP and HCCR-1, respectively. The positive rate for HCC was increased up to 74.1% in combined use of AFP and HCCR-1. Many cases (54%) for AFP-negative HCC were positive for HCCR-1 and vice versa. More importantly, the diagnostic rate for small HCC (< 2 cm) was significantly improved in the combined analysis of AFP and HCCR-1 to 56.9% although it was only 40.1% and 23.4% in the single analysis of HCCR-1 and AFP, respectively. Our result suggests that the HCCR-1 could be an useful biomarker for HCC while the diagnostic rate could be significantly improved in the combined use of HCCR-1 and AFP.

Published
2012

34. Daniel Chonghan Hong

Author

Kurtze, Douglas A., Choi, Moo Young, Kim, Yong W., and Gunton, James D.

Subjects
Hong, Daniel Chonghan -- Biography, Physics, College teachers -- Biography, Physics
Abstract

Daniel Chonghan Hong was a professor of physics at Lehigh University and was the originator of the diffusing void model of granular flow. He died of cardiac arrest, after a period of hospitalization , on 6 July 2002 in Hershey, Pennsylvania.

Published
2003

35. Turbine Vane Passage Cooling Experiments With a Close-Coupled Combustor-Turbine Interface Geometry—Part I: Describing the Flow

Author

Nawathe, Kedar P., Nath, Aaditya R., Kim, Yong W., and Simon, Terrence W.

Abstract

Due to the proximity of the first-stage gas turbine vanes to the combustor, coolant introduced to the combustor walls interacts with the endwall film coolant and changes the vane passage flow physics. Recent results show that combustor coolant contributes significantly to cooling the endwall and vane surfaces. In this paper, the traditional combustor-turbine interface was modified to improve overall cooling performance. The performance of this new injection cooling scheme on passage fluid dynamics and surface cooling is assessed. The first of this two-part paper reports detailed experimental tests that document secondary flows and coolant transport throughout the vane passage for four combustor coolant flowrates. The experimental facility imitates combustor coolant injection and engine-level turbulence and has a modified transition duct design, called the “close-coupled combustor-turbine interface.” The “impingement vortex” seen in previous studies with combustor cooling appears as the dominant secondary flow. It is observed in the present study over a wide range of flowrates, confirming its tie to the combustor coolant flowrate and not the combustor-turbine interface geometry. It was found, however, that the location and size of the impingement vortex are affected by coolant flowrate. Part II of this paper discusses the impact of the observed secondary flows on cooling vane passage surfaces.

Published
2023
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40. Transdifferentiation-inducing HCCR-1 oncogene

Author

Ha, Seon-Ah, primary, Kim, Hyun K, additional, Yoo, JinAh, additional, Kim, SangHee, additional, Shin, Seung M, additional, Lee, Youn S, additional, Hur, Soo Y, additional, Kim, Yong W, additional, Kim, Tae E, additional, Chung, Yeun J, additional, Jeun, Shin S, additional, Kim, Dong W, additional, Park, Yong G, additional, Kim, Jin, additional, Shin, Soon Y, additional, Lee, Young H, additional, and Kim, Jin W, additional

Published
2010
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