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Search Results: 1 - 10 of 62421 matches for " Jun Yong Choi "
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Automatic Classification for Various Images Collections Using Two Stages Clustering Method  [PDF]
Wan Hyun Cho, In Seop Na, Jun Yong Choi, Tae Hoon Lee
Open Journal of Applied Sciences (OJAppS) , 2013, DOI: 10.4236/ojapps.2013.31B010
Abstract: In this paper, we propose an automatic classification for various images collections using two stage clustering method. Here, we have used global and local image features. First, we review about various types of feature vector that is suita-ble to represent local and global properties of images, and similarity measures that can be represented an affinity be-tween these images. Second, we consider a clustering method for image collection. Here, we first build a coarser clus-tering by partitioning various images into several clusters using the flexible Mean shift algorithm and K-mean cluster-ing algorithm. Second, we construct dense clustering of images collection by optimizing a Gaussian Dirichlet process mixture model taking initial clusters as given coarser clustering. Finally, we have conducted the comparative experi-ments between our method and existing methods on various images datasets. Our approach has significant advantage over existing techniques. Besides integrating temporal and image content information, our approach can cluster auto-matically photographs without some assumption about number of clusters or requiring a priori information about initial clusters and it can also generalize better to different image collections.
Role of surgical resection for multiple hepatocellular carcinomas
Sung Hoon Choi,Gi Hong Choi,Seung Up Kim,Jun Yong Park
World Journal of Gastroenterology , 2013, DOI: 10.3748/wjg.v19.i3.366
Abstract: AIM: To clarify the role of surgical resection for multiple hepatocellular carcinomas (HCCs) compared to transarterial chemoembolization (TACE) and liver transplantation (LT). METHODS: Among the HCC patients who were managed at Yonsei University Health System between January 2003 and December 2008, 160 patients who met the following criteria were retrospectively enrolled: (1) two or three radiologically diagnosed HCCs; (2) no radiologic vascular invasion; (3) Child-Pugh class A; (4) main tumor smaller than 5 cm in diameter; and (5) platelet count greater than 50 000/mm3. Long-term outcomes were compared among the following three treatment modalities: surgical resection or combined radiofrequency ablation (RFA) (n = 36), TACE (n = 107), and LT (n = 17). The survival curves were computed using the Kaplan-Meier method and compared with a log-rank test. To identify the patients who gained a survival benefit from surgical resection, we also investigated prognostic factors for survival following surgical resection. Multivariate analyses of the prognostic factors for survival were performed using the Cox proportional hazard model. RESULTS: The overall survival (OS) rate was significantly higher in the surgical resection group than in the TACE group (48.1% vs 28.9% at 5 years, P < 0.005). LT had the best OS rate, which was better than that of the surgical resection group, although the difference was not statistically significant (80.2% vs 48.1% at 5 years, P = 0.447). The disease-free survival rates were also significantly higher in the LT group than in the surgical resection group (88.2% vs 11.2% at 5 years, P < 0.001). Liver cirrhosis was the only significant prognostic factor for poor OS after surgical resection. Clinical liver cirrhosis rates were 55.6% (20/36) in the resection group and 93.5% (100/107) in the TACE group. There were 19 major and 17 minor resections. En bloc resection was performed in 23 patients, multi-site resection was performed in 5 patients, and combined resection with RFA was performed in 8 patients. In the TACE group, only 34 patients (31.8%) were recorded as having complete remission after primary TACE. Seventy-two patients (67.3%) were retreated with repeated TACE combined with other therapies. In patients who underwent surgical resection, the 16 patients who did not have cirrhosis had higher 5-year OS and disease-free survival rates than the 20 patients who had cirrhosis (80.8% vs 25.5% 5-year OS rate, P = 0.006; 22.2% vs 0% 5-year disease-free survival rate, P = 0.048). Surgical resection in the 20 patients who had cirrhosis did n
Formal Implementation of a Performance Evaluation Model for the Face Recognition System
Yong-Nyuo Shin,Jason Kim,Yong-Jun Lee,Woochang Shin,Jin-Young Choi
Journal of Biomedicine and Biotechnology , 2008, DOI: 10.1155/2008/742504
Abstract: Due to usability features, practical applications, and its lack of intrusiveness, face recognition technology, based on information, derived from individuals' facial features, has been attracting considerable attention recently. Reported recognition rates of commercialized face recognition systems cannot be admitted as official recognition rates, as they are based on assumptions that are beneficial to the specific system and face database. Therefore, performance evaluation methods and tools are necessary to objectively measure the accuracy and performance of any face recognition system. In this paper, we propose and formalize a performance evaluation model for the biometric recognition system, implementing an evaluation tool for face recognition systems based on the proposed model. Furthermore, we performed evaluations objectively by providing guidelines for the design and implementation of a performance evaluation system, formalizing the performance test process.
Acupuncture Treatment of a Patient with Persistent Allergic Rhinitis Complicated by Rhinosinusitis and Asthma
Ae-Ran Kim,Jun-Yong Choi,Jong-In Kim,So-Young Jung,Sun-Mi Choi
Evidence-Based Complementary and Alternative Medicine , 2011, DOI: 10.1093/ecam/nep240
Abstract: A pathophysiologic relationship between allergic rhinitis and rhinosinusitis and asthma has long been suggested. However, few clinical studies of acupuncture have been conducted on these comorbid conditions. A 48-year-old male suffering from persistent allergic rhinitis with comorbid chronic rhinosinusitis and asthma since the age of 18 years was studied. He complained of nasal obstruction, sneezing, cough, rhinorrhea and moderate dyspnea. He occasionally visited local ear-nose-throat clinics for his nasal symptoms, but gained only periodic symptom relief. The patient was treated with acupuncture, infrared radiation to the face and electro-acupuncture. Needles were inserted at bilateral LI20, GV23, LI4 and EX-1 sites with De-qi. Electro-acupuncture was performed simultaneously at both LI20 sites and additional traditional Korean acupuncture treatments were performed. Each session lasted for 10 min and the sessions were carried out twice a week for 5 weeks. The patient’s Mini-Rhinoconjunctivitis Quality-of-Life Questionnaire score decreased from 38, at the beginning of treatment, to 23, 3 weeks after the last treatment. The Total Nasal Symptom Score was reduced from six (baseline) to five, 3 weeks after the last treatment. There was significant clinical improvement in the forced expiratory volume in 1 s—from 3.01 to 3.50 l—with discontinuation of the inhaled corticosteroid, and no asthma-related complaints were reported. Further clinical studies investigating the effectiveness of acupuncture for the patients suffering from allergic rhinitis and/or rhinosinusitis with comorbid asthma are needed.
Doxorubicin Induces Cytotoxicity through Upregulation of pERK–Dependent ATF3
Eun-Jung Park, Hyuk-Kwon Kwon, Yong-Min Choi, Hyeon-Jun Shin, Sangdun Choi
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0044990
Abstract: Although doxorubicin is commonly used in the treatment of many cancer types, its use in chemotherapy has been limited, largely because of its severe side effects, including cardiotoxicity and nephrotoxicity. In this study, we aimed to identify the mechanism of doxorubicin-induced cytotoxicity by using the human kidney proximal tubule cell line HK-2. Furthermore, we investigated the role of activating transcription factor 3 (ATF3) as a mediator of doxorubicin-induced cytotoxicity by using wild-type mouse embryonic fibroblasts (MEF) cells and ATF3 knockout (KO) cells. In HK-2 cells, doxorubicin decreased cell viability in a dose-dependent manner and induced an increase in cells in the sub G1 and G2/M phases at all doses. Doxorubicin treatment showed the following dose-dependent effects: increase in the secretion of tumor necrosis factor alpha; decrease in the expression of phosphorylated protein kinase A and Bcl-2; and increase in the expression of phosphorylated signal transducer and activator of transcription 3, phosphorylated extracellular signal-regulated kinase (ERK), and ATF3. Based on these results, we suggest that doxorubicin induces cytotoxicity through an ERK-dependent pathway, and ATF3 plays a pivotal role as a transcriptional regulator in this process.
Acupuncture for the treatment of tinnitus: a systematic review of randomized clinical trials
Jong-In Kim, Jun-Yong Choi, Dong-Hyo Lee, Tae-Young Choi, Myeong Soo Lee, Edzard Ernst
BMC Complementary and Alternative Medicine , 2012, DOI: 10.1186/1472-6882-12-97
Abstract: Fourteen databases were searched from the dates of their creation to July 4th, 2012. Randomized clinical trials (RCTs) were included if acupuncture was used as the sole treatment. The Cochrane risk of bias tool was used to assess the risk of bias.A total of 9 RCTs met all the inclusion criteria. Their methodological quality was mostly poor. Five RCTs compared the effectiveness of acupuncture or electroacupuncture with sham acupuncture for treating tinnitus. The results failed to show statistically significant improvements. Two RCTs compared a short one-time scalp acupuncture treatment with the use of penetrating sham acupuncture at non-acupoints in achieving subjective symptom relief on a visual analog scale; these RCTs demonstrated significant positive effects with scalp acupuncture. Two RCTs compared acupuncture with conventional drug treatments. One of these RCTs demonstrated that acupuncture had statistically significant effects on the response rate in patients with nervous tinnitus, but the other RCT did not demonstrate significant effects in patients with senile tinnitus.The number, size and quality of the RCTs on the effectiveness of acupuncture for the treatment of tinnitus are not sufficient for drawing definitive conclusions. Further rigorous RCTs that overcome the many limitations of the current evidence are warranted.
Moxibustion for hypertension: a systematic review
Jong-In Kim, Jun-Yong Choi, Hyangsook Lee, Myeong Soo Lee, Edzard Ernst
BMC Cardiovascular Disorders , 2010, DOI: 10.1186/1471-2261-10-33
Abstract: We searched 15 databases without language restrictions from their respective dates of inception until March 2010. We included randomized controlled trials (RCTs) comparing moxibustion to either antihypertensive drugs or no treatment. The risk of bias was assessed for each RCT.During the course of our search, we identified 519 relevant articles. A total of 4 RCTs met all the inclusion criteria, two of which failed to report favorable effects of moxibustion on blood pressure (BP) compared to the control (antihypertensive drug treatment alone). However, a third RCT showed significant effects of moxibustion as an adjunct treatment to antihypertensive drug therapy for lowering BP compared to antihypertensive drug therapy alone. The fourth RCT included in this review addressed the immediate BP-lowering effects of moxibustion compared to no treatment. None of the included RCTs reported the sequence generation, allocation concealment and evaluator blinding.There is insufficient evidence to suggest that moxibustion is an effective treatment for hypertension. Rigorously designed trials are warranted to answer the many remaining questions.By 2025, the number of adults with hypertension is predicted to be 1.56 billion worldwide [1]. Despite the efforts of conventional healthcare, more than 50% of the patients with high blood pressure (BP) fail to satisfactorily control this condition [2]. One reason is the adverse effects of many antihypertensive drugs, which result in patient noncompliance [3]. Therefore, a substantial proportion of hypertensive patients resort to complementary and alternative medicines to reduce their BP [4,5].Moxibustion is a traditional East Asian medical intervention that involves the burning of moxa (i.e., Artemisia vulgaris or mugwort) directly or indirectly at the acupuncture points. The indications of moxibustion include breech presentation, dysmenorrhea, knee osteoarthritis, diarrhea, asthma, stroke, cancer and hypertension, and so on [6,7]. Unlike th
Comparative Study on Microphytobenthic Pigments and Total Microbial Biomass by ATP in Intertidal Sediments
Sun-Yong Ha,Bo-Hyung Choi,Jun-Oh Min,Su-A Jeon
Ocean and Polar Research , 2013, DOI: 10.4217/opr.2013.35.1.039
Abstract: Biomass and community composition of microphytobentos in tidal flats were studied by HPLC analysis and also investigated to examine the relationship between microphytobenthic pigments and Adenosine-5' triphosphate (ATP) as an index of total microbial biomass in intertidal environments (muddy and sandy sediment) of Gyeonggi Bay, west coast of Korea. Microphytobenthic pigments and ATP concentration in muddy sediment were the highest at the surface while the biomass of microphytobenthos in sandy sediment was the highest at the sub-surface (0.75 cm sediment depth). The detected pigments of microphytobenthos were chlorophyll a, b (euglenophytes), c3, peridinin (dinoflagellates), fucoxanthin (diatom or chrysophytes), diadinoxanthin, alloxanthin (cryptophytes), diatoxanthin, zeaxanthin (cyanobacteria), β-carotein, and pheophytin a (the degraded product of chlorophyll a). Among the pigments which were detected, the concentration of fucoxanthin was the highest, indicating that diatoms dominated in the microphytobenthic community of the tidal flats. There was little significant correlation between OC (Organic Carbon) and ATP in both sediments. However, a positive correlation between chlorophyll a concentration and ATP concentration was found in sandy sediment, suggesting that microbial biomass could be affected by labile OC derived from microphytobenthos. These results provide information that may help us understand the relationship between microphytobenthos and microbial biomass in different intertidal sediment environments.
Quantitative analysis of proximity effect in $Nb/Co_{60}Fe_{40}$, Nb/Ni, and $Nb/Cu_{40}Ni_{60}$ bilayers
Jinho Kim,Jun Hyung Kwon,K. Char,Hyeonjin Doh,Han-Yong Choi
Physics , 2005, DOI: 10.1103/PhysRevB.72.014518
Abstract: We have studied the behavior of the superconducting critical temperature Tc in $Nb/Co_{60}Fe_{40}$, Nb/Ni, and $Nb/Cu_{40}Ni_{60}$ bilayers as a function of the thickness of each ferromagnetic metal layer. The Tc s of three sets of bilayers exhibit non-monotonic behavior as a function of each ferromagnetic metal thickness. Employing the quantitative analysis based on Usadel formalism of the effect of the exchange energy, we observed that the Tc behavior of $Nb/Co_{60}Fe_{40}$ bilayers is in good agreement with the theoretical values over the entire range of the data. On the other hand, the Tc s of Nb/Ni and $Nb/Cu_{40}Ni_{60}$ bilayers show a higher value in the small thickness regime than the theoretical prediction obtained from the calculation, which matches the dip position and the saturation value of Tc in the large thickness limit. This discrepancy is probably due to the weakened magnetic properties of Ni and $Cu_{40}Ni_{60}$ when they are thin. We discuss the values of our fitting parameters and its implication on the validity of the current Usadel formalism of the effect of the exchange energy.
Intrinsic finite-size effects in the two-dimensional XY model with irrational frustration
Sung Yong Park,M. Y. Choi,Beom Jun Kim,Gun Sang Jeon,Jean S. Chung
Physics , 2000,
Abstract: This study investigates in detail the finite-size scaling of the two-dimensional irrationally frustrated XY model. By means of Monte Carlo simulations with entropic sampling, we examine the size dependence of the specific heat, and find remarkable deviation from the conventional finite-size scaling theory, which reveals novel intrinsic finite-size effects. Relaxation dynamics of the system is also considered, and correspondingly, finite-size scaling of the relaxation time is examined, again giving evidence for the intrinsic finite-size effects and suggesting a zero-temperature glass transition.
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