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Search Results: 1 - 10 of 29092 matches for " Won Yong Cho "
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Load-Measuring Pot Bearing with Built-In Load Cell —Part II: Fatigue Performance and Experimental Temperature Correction  [PDF]
Jeong-Rae Cho, Young Jin Kim, Jong-Won Kwark, Sung Yong Park, Won Jong Chin, Byung-Suk Kim
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.511108
Abstract:

This paper presents the results of fatigue performance tests performed up to 10 million cycles on a load-measuring pot bearing with built-in load cell to verify its field applicability and proposes an empirical temperature correction formula. In Part I of this work, various measurement performances of the load-measuring pot bearing were evaluated through static and dynamic loading tests. Bridge bearings are subjected to the effect of fatigue caused by the repeated application of moving loads and exposed to harsh site conditions including cold and hot weathers differently to laboratory conditions. Accordingly, the durability of the load-measuring pot bearing with built-in load cell shall be secured and the environmental effects like temperature shall be minimized for its application on field. This study conducted fatigue tests up to 10 million cycles on a load-measuring pot bearing with the capacity of 1000 kN to examine eventual degradation of the measurement accuracy with respect to the number of fatigue loading cycles. In addition, the experimental temperature correction procedure is proposed to obtain the temperature correction formula enabling to correct the effect of temperature on the load measurement.

Load-Measuring Pot Bearing with Built-In Load Cell —Part I: Design and Performance  [PDF]
Jeong-Rae Cho, Young Jin Kim, Jong-Won Kwark, Sung Yong Park, Won Jong Chin, Byung-Suk Kim
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.511104
Abstract:

This paper presents the underlying principle and the results of various performance evaluations for a load-measuring pot bearing with built-in load cell. The pot bearing composed of a pot made of steel in which an elastomer disk is inserted is a bearing supporting larger loads than the elastomeric bearing and accommodating rotational movement. Owing to a Poisson’s ratio close to 0.5, elastomer withstands hydrostatic pressure when confined in a rigid body. Accounting for this principle, the vertical load applied on the pot bearing can be obtained by converting the pressure acting on the elastomer. Therefore, a load-measuring pot bearing is developed in this study by embedding a load cell exhibiting remarkable durability in the base plate of the bearing. The details for the insertion of the load cell in the base plate of the pot were improved through finite element analysis to secure sufficient measurement accuracy. The evaluation of the static performance of the pot bearing applying these improved details verified that the bearing exhibited sufficient accuracy for the intended measurement purpose. The dynamic performance evaluation results indicated that accurate measurement of the dynamic load was also achieved without time lag.

Evaluation of the Surface of Nitinol after MR Polishing Process  [PDF]
Byung-Chan Kim, Jung-Won Lee, Seok-Jae Ha, Yong-Kyu Cho, Dong-Sung Kang, Myeong-Woo Cho
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.32031
Abstract:

Nitinol is used in various industries, especially for biomaterials. Generally, the surface integrity of sub-micron level and non-surface flaw is required in nitinol for biomaterial. However, surface flaws, such as scratches, pits, and residual stress, can occur on the polished surface, and it is difficult to remove these surface flaws. The corrosion is accelerated continuously and causes bad influence in the body. Therefore, in this study, conventional polishing and MR polishing were used to minimize the corrosion and residual stress when the nitinol is used as biomaterial. X-ray diffraction and Tafel extrapolation were used to investigate the residual stress and the corrosion, and the strain hardening was investigated by nanoindentation. Surface integrities were also evaluated by SEM image and surface roughness results. As a result, the increased residual stress in conventional polishing was decreased by MR polishing. The result of corrosion test was improved from ?301 mV to ?280 mV. The residual stress was improved from ?38.18 MPa to ?31.17 MPa. Finally, it is certified that MR polishing can be used to minimize surface flaws and to improve the corrosion properties.

Clarifying the Role of Distance in Friendships on Twitter: Discovery of a Double Power-Law Relationship
Won-Yong Shin,Jaehee Cho,André M. Everett
Computer Science , 2015,
Abstract: This study analyzes friendships in online social networks involving geographic distance with a geo-referenced Twitter dataset, which provides the exact distance between corresponding users. We start by introducing a strong definition of "friend" on Twitter, requiring bidirectional communication. Next, by utilizing geo-tagged mentions delivered by users to determine their locations, we introduce a two-stage distance estimation algorithm. As our main contribution, our study provides the following newly-discovered friendship degree related to the issue of space: The number of friends according to distance follows a double power-law (i.e., a double Pareto law) distribution, indicating that the probability of befriending a particular Twitter user is significantly reduced beyond a certain geographic distance between users, termed the separation point. Our analysis provides much more fine-grained social ties in space, compared to the conventional results showing a homogeneous power-law with distance.
Carotid Endarterectomy for Symptomatic Complete Occlusion of the Internal Carotid Artery
Cho,Yong-Pil,Kwon,Tae-Won,Kwon,Sun U.,Chae,Won-Young
Acta Medica Okayama , 2011,
Abstract: We described 9 consecutive patients who underwent operative carotid artery exploration with attempted carotid endarterectomy (CEA) for symptomatic internal carotid artery (ICA) occlusion. Indications for this surgery based on vascular imaging included segmental occlusion of the proximal ICA and also extensive occlusion of the distal ICA in selected patients in whom color-flow duplex ultrasound showed a poorly echogenic or anechoic thrombus with a flow void, suggestive of an acute thrombus. CEA was performed successfully to restore blood flow in all 9 patients:CEA in 5 and CEA with Fogarty thrombectomy in 4. Postoperative magnetic resonance (MR) angiography confirmed that revascularization had been successful in all 9 patients, and MR imaging displayed improved perfusion in 4 patients. Despite the lack of a generalized efficacy of surgical revascularization for symptomatic ICA occlusion, our study demonstrated that preoperative vascular imaging allows the selection of patients who may benefit from CEA.
Effects of the combination of P3-based GKT and reality monitoring on deceptive classification
Ki-Won Jang,Deok-Yong Kim,Sungkun Cho,Jang-Han Lee
Frontiers in Human Neuroscience , 2013, DOI: 10.3389/fnhum.2013.00018
Abstract: The study aimed to investigate whether a combination of the P3-based Guilty Knowledge Test (GKT) and reality monitoring (RM) distinguished between individuals who are guilty, witnesses, or informed, and using both tests provided more accurate information than did the use of either measure alone. Participants consisted of 45 males that were randomly and evenly assigned to three groups (i.e., guilty, witness, and informed). The guilty group conducted a mock crime where they intentionally crashed their vehicle into another vehicle in a virtual environment (VE). As those in the witness group drove their own vehicles, they observed the guilty groups' vehicle crash into another vehicle. The informed group read an account and saw screenshots of the accident. All participants were instructed to insist that they were innocent. Subsequently, they performed the P3-based GKT and wrote an account of the accident for the RM analysis. A higher P3 amplitude corresponded to how well the participants recognized the presented stimulus, and a higher RM score corresponded to how well the participants reported vivid sensory information and how much less they reported uncertain information. Findings for the P3-based GKT indicated that the informed group showed lower P3 amplitude when presented with the probe stimulus than did the guilty and witness groups. Regarding the RM analysis, the informed group obtained higher RM scores on visual, temporal, and spatial details and lower scores on cognitive operations than the guilty and witness groups. Finally, discriminant analysis revealed that the combination of the P3-based GKT and RM more accurately distinguished between the three groups than the use of either measure alone. The findings suggest that RM may build upon a weakness of the P3-based GKT's. More specifically, it may build upon its susceptibility to the leakage of information about the crime, therefore helping protect innocent individuals who have information about a crime from being perceived as guilty.
A New Understanding of Friendships in Space: Complex Networks Meet Twitter
Won-Yong Shin,Bikash C. Singh,Jaehee Cho,André M. Everett
Computer Science , 2015,
Abstract: Studies on friendships in online social networks involving geographic distance have so far relied on the city location provided in users' profiles. Consequently, most of the research on friendships have provided accuracy at the city level, at best, to designate a user's location. This study analyzes a Twitter dataset because it provides the exact geographic distance between corresponding users. We start by introducing a strong definition of "friend" on Twitter (i.e., a definition of bidirectional friendship), requiring bidirectional communication. Next, we utilize geo-tagged mentions delivered by users to determine their locations, where "@username" is contained anywhere in the body of tweets. To provide analysis results, we first introduce a friend counting algorithm. From the fact that Twitter users are likely to post consecutive tweets in the static mode, we also introduce a two-stage distance estimation algorithm. As the first of our main contributions, we verify that the number of friends of a particular Twitter user follows a well-known power-law distribution (i.e., a Zipf's distribution or a Pareto distribution). Our study also provides the following newly-discovered friendship degree related to the issue of space: The number of friends according to distance follows a double power-law (i.e., a double Pareto law) distribution, indicating that the probability of befriending a particular Twitter user is significantly reduced beyond a certain geographic distance between users, termed the separation point. Our analysis provides concrete evidence that Twitter can be a useful platform for assigning a more accurate scalar value to the degree of friendship between two users.
Comparison of Extraction Methods to Detect Porcine Circovirus-2 and Porcine Reproductive and Respiratory Syndrome Virus in Semen Samples
Yong-Il Cho,Ho-Seong Cho,Gee-Wook Shin,Jung-Kee Kwon,Chul Park,Won-Il Kim
Journal of Animal and Veterinary Advances , 2012, DOI: 10.3923/javaa.2012.3175.3178
Abstract: Since, Porcine Circo Virus-2 (PCV2) and Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) are shed in semen for a long period of time after infection and artificial insemination is a common practice in pig farms, semen is an important source of spreading these viruses to naive populations. Therefore, rapid and accurate detection of PCV2 or PRRSV in semen could be critical at the standpoint of disease prevention and control. In this study, the performance of three different extraction methods on semen samples was compared to determine an optimal extraction method for semen samples to detect PCV2 or PRRSV. Seven or 115 semen samples were collected from the boars experimentally challenged with PRRSV or PCV2, respectively. These two sets of the semen samples were processed by three different extraction methods: High-Throughput Total Nucleic Acids Isolation kit (HT-TNA), High-Throughput Viral RNA Isolation kit with modified procedure (mHT-VR) and DNeasy kit or RNeasy kit for PCV2 or PRRSV, respectively. Then, the efficiency of the extraction methods were compared by conducting the same real-time PCR for each virus. HT-TNA and mHT-VR kits were faster and more convenient to process semen samples and HT-TNA kit showed higher or compatible sensitivity as compared to the other two methods while all three methods demonstrated 100% specificity. In conclusion, the HT-TNA Extraction Method could significantly reduce testing time and effort to process semen samples and showed better sensitivity for detection of PCV2 and PRRSV in semen.
The Genome Sequence of ‘Mycobacterium massiliense’ Strain CIP 108297 Suggests the Independent Taxonomic Status of the Mycobacterium abscessus Complex at the Subspecies Level
Yong-Joon Cho, Hana Yi, Jongsik Chun, Sang-Nae Cho, Charles L. Daley, Won-Jung Koh, Sung Jae Shin
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0081560
Abstract: Members of the Mycobacterium abscessus complex are rapidly growing mycobacteria that are emerging as human pathogens. The M. abscessus complex was previously composed of three species, namely M. abscessus sensu stricto, ‘M. massiliense’, and ‘M. bolletii’. In 2011, ‘M. massiliense’ and ‘M. bolletii’ were united and reclassified as a single subspecies within M. abscessus: M. abscessus subsp. bolletii. However, the placement of ‘M. massiliense’ within the boundary of M. abscessus subsp. bolletii remains highly controversial with regard to clinical aspects. In this study, we revisited the taxonomic status of members of the M. abscessus complex based on comparative analysis of the whole-genome sequences of 53 strains. The genome sequence of the previous type strain of ‘Mycobacterium massiliense’ (CIP 108297) was determined using next-generation sequencing. The genome tree based on average nucleotide identity (ANI) values supported the differentiation of ‘M. bolletii’ and ‘M. massiliense’ at the subspecies level. The genome tree also clearly illustrated that ‘M. bolletii’ and ‘M. massiliense’ form a distinct phylogenetic clade within the radiation of the M. abscessus complex. The genomic distances observed in this study suggest that the current M. abscessus subsp. bolletii taxon should be divided into two subspecies, M. abscessus subsp. massiliense subsp. nov. and M. abscessus subsp. bolletii, to correspondingly accommodate the previously known ‘M. massiliense’ and ‘M. bolletii’ strains.
Outcome of laparoscopic cholecystectomy is not influenced by chronological age in the elderly
Hyung Ook Kim, Jung Won Yun, Jun Ho Shin, Sang Il Hwang, Yong Kyun Cho, Byung Ho Son, Chang Hak Yoo, Yong Lai Park, Hungdai Kim
World Journal of Gastroenterology , 2009,
Abstract: AIM: To evaluate the outcome of laparoscopic cholecystectomy (LC) in patients aged 80 years and older.METHODS: A total of 353 patients aged 65 to 79 years (group 1) and 35 patients aged 80 years and older (group 2) underwent LC. Patients were further classified into two other groups: those with uncomplicated gallbladder disease (group A) or those with complicated gallbladder disease (group B).RESULTS: There were no significant differences between the age groups (groups 1 and 2) with respect to clinical characteristics such as age, gender, comorbid disease, or disease presentation. Mean operative time, conversion rate, and the incidence of major postoperative complications were similar in groups 1 and 2. However, the percentage of high-risk patients was significantly higher in group 2 than in group 1 (20.0% vs 5.7%, P < 0.01). Group A comprised 322 patients with a mean age of 71.0 ± 5.3 years, and group B comprised 51 patients with a mean age of 69.9 ± 4.8 years. In group B, mean operative time (78.4 ± 49.3 min vs 58.3 ± 35.8 min, P < 0.01), mean postoperative hospital stay (7.9 ± 6.5 d vs 5.0 ± 3.7 d, P < 0.01), and the incidence of major postoperative complications (9.8% vs 3.1%, P < 0.05) were significantly greater than in group A. The conversion rate tended to be higher in group B, but this difference was not significant.CONCLUSION: Perioperative outcomes in elderly patients who underwent LC seem to be influenced by the severity of gallbladder disease, and not by chronologic age. In octogenarians, LC should be performed at an earlier, uncomplicated stage of the disease whenever possible to improve perioperative outcomes.
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