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Search Results: 1 - 10 of 27679 matches for " Ki-Ho Chang "
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On the Dynamical Analysis in Aftershock Networks  [PDF]
Woon-Hak Baek, Kyungsik Kim, Ki-Ho Chang, Seung-Kyu Seo, Jun-Ho Lee, Dong-In Lee
Open Journal of Earthquake Research (OJER) , 2018, DOI: 10.4236/ojer.2018.71002
We investigate the dynamical behavior of aftershocks in earthquake networks, and the earthquake network calculated from a time series is constructed by contemplating cell resolution and temporal causality. We attempt to connect an earthquake network using relationship between one main earthquake and its aftershocks from seismic data of California. We mainly examine some topological properties of the earthquake such as the degree distribution, the characteristic path length, the clustering coefficient, and the global efficiency. Our result cannot presently determine the universal scaling exponents in statistical quantities, but the topological properties may be inferred to advance and improve by implementing the method and its technique of networks. Particularly, it may be dealt with a network issue of convenience and of importance in the case how large networks construct in time to proceed on earthquake systems.
Dynamical Structures of High-Frequency Financial Data
Kyungsik Kim,Seong-Min Yoon,Soo Yong Kim,Ki-Ho Chang,Yup Kim
Physics , 2005,
Abstract: We study the dynamical behavior of high-frequency data from the Korean Stock Price Index (KOSPI) using the movement of returns in Korean financial markets. The dynamical behavior for a binarized series of our models is not completely random. The conditional probability is numerically estimated from a return series of KOSPI tick data. Non-trivial probability structures can be constituted from binary time series of autoregressive (AR), logit, and probit models, for which the Akaike Information Criterion shows a minimum value at the 15th order. From our results, we find that the value of the correct match ratio for the AR model is slightly larger than the findings of other models.
New View on the Initial Development Site and Radiographic Classification System of Osteoarthritis of the Knee Based on Radiographic Analysis
Ki-Ho Moon
International Journal of Biomedical Science , 2012,
Abstract: Introduction: Radiographic pathology of severe osteoarthritis of the knee (OAK) such as severe osteophyte at tibial spine (TS), compartment narrowing, marginal osteophyte, and subchondral sclerosis is well known. Kellgren-Lawrence grading system, which is widely used to diagnose OAK, describes narrowing-marginal osteophyte in 4-grades but uses osteophyte at TS only as evidence of OAK without detailed-grading. However, kinematically the knee employs medial TS as an axis while medial and lateral compartments carry the load, suggesting that early OAK would occur sooner at TS than at compartment. Then, Kellgren-Lawrence system may be inadequate to diagnose early-stage OAK manifested as a subtle osteophyte at TS without narrowing-marginal osteophyte. This undiagnosed-OAK will deteriorate becoming a contributing factor in an increasing incidence of OAK. Methods: This study developed a radiographic OAK-marker based on both osteophyte at TS and compartment narrowing-marginal osteophyte and graded as normal, mild, moderate, and severe. With this marker, both knee radiographs of 1,728 patients with knee pain were analyzed.Results: Among 611 early-stage mild OAK, 562 or 92% started at TS and 49 or 8% at compartment. It suggests the initial development site of OAK, helping develop new site-specific radiographic classification system of OAK accurately to diagnose all severity of OAK at early, intermediate, or late-stage. It showed that Kellgren-Lawrence system missed 92.0% of early-stage mild OAK from diagnosis. Conclusions: A subtle osteophyte at TS is the earliest radiographic sign of OAK. A new radiographic classification system of OAK was suggested for accurate diagnosis of all OAK in severity and at stage.
Comparison of the bright band characteristics measured by Micro Rain Radar (MRR) at a mountain and a coastal site in South Korea
Comparison of the Bright Band Characteristics Measured by Micro Rain Radar (MRR) at a Mountain and a Coastal Site in South Korea

Joo-Wan Cha,Ki-Ho Chang,Seong Soo Yum,Young-Jean Choi,
Joo-Wan CHA
,Ki-Ho CHANG,Seong Soo YUM,Young-Jean CHOI

大气科学进展 , 2009,
Abstract: Data from a long term measurement of Micro Rain Radar (MRR) at a mountain site (Daegwallyeong, DG, one year period of 2005) and a coastal site (Haenam, HN, three years 2004--2006) in South Korea were analyzed to compare the MRR measured bright band characteristics of stratiform precipitation at the two sites. On average, the bright band was somewhat thicker and the sharpness (average gradient of reflectivity above and below the reflectivity peak) was slightly weaker at DG, compared to those values at HN. The peak reflectivity itself was twice as strong and the relative location of the peak reflectivity within the bright band was higher at HN than at DG. Importantly, the variability of these values was much larger at HN than at DG. The key parameter to cause these differences is suggested to be the difference of the snow particle densities at the two sites, which is related to the degree of riming. Therefore, it is speculated that the cloud microphysical processes at HN may have varied significantly from un-rimed snow growth, producing low density snow particles, to the riming of higher density particles, while snow particle growth at DG was more consistently affected by the riming process, and therefore high density snow particles. Forced uplifting of cloudy air over the mountain area around DG might have resulted in an orographic supercooling effect that led to the enhanced riming of supercooled cloud drops.
Preliminary Results of the Ground-Based Orographic Snow Enhancement Experiment for the Easterly Cold Fog (Cloud) at Daegwallyeong during the 2006 Winter
Preliminary Results of the Ground-Based Orographic Snow Enhancement Experiment for the Easterly Cold Fog (Cloud) at Daegwallyeong during the 2006 Winter

Myoung-Joo LEE,Ki-Ho CHANG,Gyun-Myoung PARK,Jin-Yim JEONG,Ha-Young YANG,Ki-Deok JEONG,Joo-Wan CHA,Sung-Soo YUM,Jae-Cheol NAM,Kyungsik KIM,Byung-Chul CHOI,
Myoung-Joo LEE
,Ki-Ho CHANG,Gyun-Myoung PARK,Jin-Yim JEONG,Ha-Young YANG,Ki-Deok JEONG,Joo-Wan CHA,Sung-Soo YUM,Jae-Cheol NAM,Kyungsik KIM,Byung-Chul CHOI

大气科学进展 , 2009,
Abstract: The snow enhancement experiments, carried out by injecting AgI and water vapor into orographically enhanced clouds (fog), have been conducted to confirm Li and Pitter's forced condensation process in a natural situation. Nine ground-based experiments have been conducted at Daegwallyeong in the Taebaek Mountains for the easterly foggy days from January--February 2006. We then obtained the optimized conditions for the Daegwallyeong region as follows: the small seeding rate (1.04 g min-1) of AgI for the easterly cold fog with the high humidity of Gangneung. Additional experiments are needed to statistically estimate the snowfall increment caused by the small AgI seeding into the orographical fog (cloud) over the Taebaek Mountains.
Herbal Medicines for Parkinson's Disease: A Systematic Review of Randomized Controlled Trials
Tae-Hun Kim, Ki-Ho Cho, Woo-Sang Jung, Myeong Soo Lee
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0035695
Abstract: Objective We conducted systematic review to evaluate current evidence of herbal medicines (HMs) for Parkinson's disease (PD). Methods Along with hand searches, relevant literatures were located from the electronic databases including CENTRAL, MEDLINE, EMBASE, CINAHL, AMED, PsycInfo, CNKI, 7 Korean Medical Databases and J-East until August, 2010 without language and publication status. Randomized controlled trials (RCTs), quasi-randomized controlled trials and randomized crossover trials, which evaluate HMs for idiopathic PD were selected for this review. Two independent authors extracted data from the relevant literatures and any disagreement was solved by discussion. Results From the 3432 of relevant literatures, 64 were included. We failed to suggest overall estimates of treatment effects on PD because of the wide heterogeneity of used herbal recipes and study designs in the included studies. When compared with placebo, specific effects were not observed in favor of HMs definitely. Direct comparison with conventional drugs suggested that there was no evidence of better effect for HMs. Many studies compared combination therapy with single active drugs and combination therapy showed significant improvement in PD related outcomes and decrease in the dose of anti-Parkinson's drugs with low adverse events rate. Conclusion Currently, there is no conclusive evidence about the effectiveness and efficacy of HMs on PD. For establishing clinical evidence of HMs on PD, rigorous RCTs with sufficient statistical power should be promoted in future.
Impact of adequate empirical combination therapy on mortality from bacteremic Pseudomonas aeruginosa pneumonia
Park So-Youn,Park Hyun,Moon Song,Park Ki-Ho
BMC Infectious Diseases , 2012, DOI: 10.1186/1471-2334-12-308
Abstract: Background Pseudomonas aeruginosa has gained an increasing amount of attention in the treatment of patients with pneumonia. However, the benefit of empirical combination therapy for pneumonia remains unclear. We evaluated the effects of adequate empirical combination therapy and multidrug-resistance in bacteremic Pseudomonas pneumonia on the mortality. Methods A retrospective cohort study was performed at the 2,700-bed tertiary care university hospital. We reviewed the medical records of patients with bacteremic pneumonia between January 1997 and February 2011. Patients who received either inappropriate or appropriate empirical therapy were compared by using marginal structural model. Furthermore, we investigated the direct impact of combination therapy on clinical outcomes in patients with monomicrobial bacteremic pneumonia. Results Among 100 consecutive patients with bacteremic Pseudomonas pneumonia, 65 patients were classified in the adequate empirical therapy group, 32 of whom received monotherapy and 33 combination therapy. In the marginal structural model, only inadequate therapy was significantly associated with 28-day mortality (p = 0.02), and multidrug-resistance was not a significant risk factor. To examine further the direct impact of combination therapy, we performed a subgroup analysis of the 65 patients who received adequate therapy. Multivariate logistic regression analysis identified absence of septic shock at the time of bacteremia (OR, 0.07; 95% CI, 0.01-0.49; p = 0.008), and adequate combination therapy (OR, 0.05; 95% CI, 0.01-0.34; p = 0.002) as variables independently associated with decreased all-cause 28-day mortality. Conclusions Our study suggests that adequate empirical combination therapy can decrease mortality in patients with bacteremic Pseudomonas pneumonia.
Anti-Cancer Activity of a Novel Small Molecule Compound That Simultaneously Activates p53 and Inhibits NF-κB Signaling
Sun Gwan Hwang, Jinah Park, Joo Young Park, Cheol Hyoung Park, Ki-Ho Lee, Jeong Woo Cho, Jong-Ik Hwang, Jae Young Seong
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0044259
Abstract: The p53 and NF-κB pathways play important roles in diverse cellular functions, including cell growth, apoptosis, and tumorigenesis. Mutations that inactivate the p53 gene and constitutive NF-κB pathway activation are common occurrences in human cancers. Although many drugs are being developed that selectively activate p53 or inhibit NF-κB, there are few drug candidates that can do both. Simultaneous activation of p53 and inhibition of the NF-κB pathway is therefore a prime target for new cancer drug development. This study is the first report of a high-throughput approach with mass compounds that concurrently target both pathways. Using a cell-based screening assay and a library of 200,000 synthetic compounds, we identified 9 small molecules that simultaneously inhibit NF-κB and activate p53. One of these compounds, N-2, increased the expression of p53 target genes, including p21 and GADD45a. In addition, N-2 inhibited the transcriptional activity of NF-κB, concomitantly repressing interleukin-6 and monocyte chemotactic protein-1 (MCP-1) expression. When cell lines derived from a diverse range of cancers were treated in vitro with N-2, we observed increased cell death. N-2 also significantly inhibited allograft growth in murine models of melanoma and lung carcinoma. Our findings suggest that N-2 may act as a bivalent anti-cancer agent through simultaneous modulation of NF-κB and p53 activities.
Changes in Serum Levels of Bone Morphogenic Protein 4 and Inflammatory Cytokines after Bariatric Surgery in Severely Obese Korean Patients with Type 2 Diabetes
Mee Kyoung Kim,Eun-Hee Jang,Oak-Kee Hong,Hyun-Ji Chun,Soon-Jib Yoo,Ki-Hyun Baek,Wook Kim,Eung Kook Kim,Ki-Ho Song,Hyuk-Sang Kwon
International Journal of Endocrinology , 2013, DOI: 10.1155/2013/681205
Abstract: Serum bone morphogenic protein- (BMP-) 4 levels are associated with human adiposity. The aim of this study was to investigate changes in serum levels of BMP-4 and inflammatory cytokines after Roux-en-Y gastric bypass (RYGB). Fifty-seven patients with type 2 diabetes underwent RYGB. Serum levels of BMP-4 and various inflammatory markers, including high-sensitivity C-reactive protein (hsCRP), free fatty acids (FFAs), and plasminogen activator inhibitor- (PAI-) 1, were measured before and 12 months after RYGB. Remission was defined as glycated hemoglobin <6.5% for at least 1 year in the absence of medications. Levels of PAI-1, hsCRP, and FFAs were significantly decreased at 1 year after RYGB. BMP-4 levels were also significantly lower at 1 year after RYGB than at baseline ( ). Of the 57 patients, 40 (70%) had diabetes remission at 1 year after surgery (remission group). Compared with patients in the nonremission group, patients in the remission group had lower PAI-1 levels and smaller visceral fat areas at baseline. There was a difference in the change in the BMP-4 level according to remission status. Our data demonstrate a significant beneficial effect of bariatric surgery on established cardiovascular risk factors and a reduction in chronic nonspecific inflammation after surgery. 1. Introduction Bone morphogenic proteins (BMPs) are members of the transforming growth factor-β superfamily. Although they were originally identified as bone-inducing proteins, the activities of BMPs are not restricted to bone formation [1]. Recent data indicate that BMP-4 induces the differentiation of white fat, the predominant type of adipose tissue [2]. Exposing pluripotent 10T1/2 cells to exogenous BMP-4 induces adipocyte lineage commitment [3]. Adipocyte precursor cells (APCs) derived from subcutaneous fat differentiate well in the presence of classical induction cocktail, whereas those from visceral fat differentiate poorly but can be induced to differentiate by addition of BMP-4 [4]. Activation of BMP-4 signaling may be associated with increased adiposity in humans [3]. It is still unclear whether BMP-4 acts via an endocrine mechanism or an autocrine pathway and whether cellular expression of BMP-4 reflects circulating blood levels of BMP-4 [5]. Recently, we showed that serum BMP-4 levels are associated with human adiposity, insulin resistance, and metabolic syndrome in nondiabetic subjects [6]. However, no studies have investigated the changes in BMP-4 levels in severely obese patients with type 2 diabetes after bariatric surgery. Adipose tissue is suggested to
Chronic Resveratrol Treatment Protects Pancreatic Islets against Oxidative Stress in db/db Mice
Young-Eun Lee, Ji-Won Kim, Eun-Mi Lee, Yu-Bae Ahn, Ki-Ho Song, Kun-Ho Yoon, Hyung-Wook Kim, Cheol-Whee Park, Guolian Li, Zhenqi Liu, Seung-Hyun Ko
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0050412
Abstract: Resveratrol (RSV) has anti-inflammatory and anti-oxidant actions which may contribute to its cardiovascular protective effects. We examined whether RSV has any beneficial effects on pancreatic islets in db/db mice, an animal model of type 2 diabetes. The db/db and db/dm mice (non-diabetic control) were treated with (db-RSV) or without RSV (db-control) (20 mg/kg daily) for 12 weeks. After performing an intraperitoneal glucose tolerance test and insulin tolerance test, mice were sacrificed, the pancreas was weighed, pancreatic β-cell mass was quantified by point count method, and the amount of islet fibrosis was determined. 8-Hydroxydeoxyguanosine (8-OHdG), an oxidative stress marker, was determined in 24 h urine and pancreatic islets. RSV treatment significantly improved glucose tolerance at 2 hrs in db/db mice (P = 0.036), but not in db/dm mice (P = 0.623). This was associated with a significant increase in both pancreas weight (P = 0.011) and β-cell mass (P = 0.016). Islet fibrosis was much less in RSV-treated mice (P = 0.048). RSV treatment also decreased urinary 8-OHdG levels (P = 0.03) and the percentage of islet nuclei that were positive for 8-OHdG immunostaining (P = 0.019). We conclude that RSV treatment improves glucose tolerance, attenuates β-cell loss, and reduces oxidative stress in type 2 diabetes. These findings suggest that RSV may have a therapeutic implication in the prevention and management of diabetes.
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