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Search Results: 1 - 10 of 25267 matches for " Jinhyuk Lee "
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A Photometric Study of Five Open Clusters in the SDSS
Jinhyuk Ryu,Myung Gyoon Lee
Physics , 2011, DOI: 10.5303/JKAS.2011.44.5.177
Abstract: We present a photometric study of five open clusters (Czernik 5, Alessi 53, Berkeley 49, Berkeley 84, and Pfleiderer 3) in the Sloan Digital Sky Survey. The position and size of these clusters are determined using the radial number density profiles of the stars, and the member stars of the clusters are selected using the proper motion data in the literature. We estimate the reddening, distance, and age of the clusters based on the isochrone fitting in the color-magnitude diagram. The foreground reddenings for these clusters are estimated to be E(B-V) = 0.71 - 1.55 mag. The distances to these clusters are derived to be 2.0 - 4.4 kpc, and their distances from the Galactic center range from 7.57 kpc to 12.35 kpc. Their ages are in the range from 250 Myr to 1 Gyr. Berkeley 49 and Berkeley 84 are located in the Orion spur, Czernik 5 is in the Perseus arm, and Pfleiderer 3 and Alessi 53 are at beyond the Perseus arm.
Intellectual Interchanges in the History of Massive Online Open-editing Encyclopedia, Wikipedia
Jinhyuk Yun,Sang Hoon Lee,Hawoong Jeong
Computer Science , 2015,
Abstract: Wikipedia is a free Internet encyclopedia with enormous amount of contents. This encyclopedia is written by volunteers with various backgrounds in a collective fashion; anyone can access and edit most of the articles. This open editing nature may give us prejudice that Wikipedia is unstable and unreliable sources; yet many studies suggest that Wikipedia is even more accurate and self-consistent than traditional encyclopedias. Scholars have attempted to understand such extraordinary credibility, but usually used the edit number without consideration of real-time. In this work, we probe the formation of such collective intelligence through the systematic analysis using the entire history of 34,534,110 English Wikipedia articles, between 2001 and 2014. From this massive data set, we observe the universality of both timewise and lengthwise editing scales, which suggests that it is essential to consider the real-time dynamics. By considering real-time, we find the existence of various growth patterns that are unobserved in terms of the number of edits as the time step. To account these results, we present a mechanistic model that adopts both the article editing dynamics based on editor-editor and editor-article interactions. The model successfully generates some key properties of the real Wikipedia articles such as distinct types of articles for the editing patterns characterized by the interrelationship between the numbers of edits and editors, and the article size. In addition, the model indicates that infrequently referred articles tend to grow faster than frequently referred one, and articles attracting high motivation of edit counterintuitively reduce the number of participants. We suggest that this decay of participants eventually brings inequality among the editors, which will be more severe with time.
Computational Prediction of Protein-Protein Interactions of Human Tyrosinase
Su-Fang Wang,Sangho Oh,Yue-Xiu Si,Zhi-Jiang Wang,Hong-Yan Han,Jinhyuk Lee,Guo-Ying Qian
Enzyme Research , 2012, DOI: 10.1155/2012/192867
Abstract: The various studies on tyrosinase have recently gained the attention of researchers due to their potential application values and the biological functions. In this study, we predicted the 3D structure of human tyrosinase and simulated the protein-protein interactions between tyrosinase and three binding partners, four and half LIM domains 2 (FHL2), cytochrome b-245 alpha polypeptide (CYBA), and RNA-binding motif protein 9 (RBM9). Our interaction simulations showed significant binding energy scores of ?595.3?kcal/mol for FHL2, ?859.1?kcal/mol for CYBA, and ?821.3?kcal/mol for RBM9. We also investigated the residues of each protein facing toward the predicted site of interaction with tyrosinase. Our computational predictions will be useful for elucidating the protein-protein interactions of tyrosinase and studying its binding mechanisms. 1. Introduction Tyrosinase (EC is ubiquitously distributed in organisms and is a critical enzyme involved in melanin production, with multiple catalytic functions in pigment production [1–3]. Tyrosinase mutations are directly linked to pigmentation disorders in mammals [4, 5] and can cause a browning effect in vegetables [6, 7]. In addition, tyrosinase participates in cuticle formation in insects [8, 9]. In mammals, tyrosinase is a bifunctional enzyme that first converts tyrosine to DOPA and then to DOPA quinone, which is further cyclized and oxidized to produce melanin pigments [10]. The human tyrosinase protein contains two Cu2+-binding sites, two cysteine rich regions, a signal peptide region, a transmembrane anchor domain, and an EGF motif [11]. Two Cu2+ ions in the active site of tyrosinase are coordinated by three histidine residues each and are essential for the enzyme’s catalytic activity [12]. Furthermore, the presence of Cu2+ in the active site of tyrosinase is observed across numerous organisms [13]. Therefore, chelation of tyrosinase Cu2+ by synthetic compounds or agents from natural sources has been targeted as a way to block tyrosinase catalysis for medicinal purposes, darkening problems in agricultural products, and cosmetic interests [14, 15]. As the crystallographic structure of tyrosinase has been gradually elucidated, insights into its catalytic mechanisms and active site have also been revealed [16–18]. However, while the catalytic mechanism of tyrosinase-mediated melanin pigment production has been well studied, the relationship between tyrosinase enzyme activity and protein interactions has not been fully elucidated, despite several reports of interacting proteins for tyrosinase [19–22].
The Effect of D-(?)-arabinose on Tyrosinase: An Integrated Study Using Computational Simulation and Inhibition Kinetics
Hong-Jian Liu,Sunyoung Ji,Yong-Qiang Fan,Li Yan,Jun-Mo Yang,Hai-Meng Zhou,Jinhyuk Lee,Yu-Long Wang
Enzyme Research , 2012, DOI: 10.1155/2012/731427
Abstract: Tyrosinase is a ubiquitous enzyme with diverse physiologic roles related to pigment production. Tyrosinase inhibition has been well studied for cosmetic, medicinal, and agricultural purposes. We simulated the docking of tyrosinase and D-(?)-arabinose and found a binding energy of ?4.5?kcal/mol for theup-formof D-(?)-arabinose and ?4.4?kcal/mol for thedown-form of D-(?)-arabinose. The results of molecular dynamics simulation suggested that D-(?)-arabinose interacts mostly with HIS85, HIS259, and HIS263, which are believed to be in the active site. Our kinetic study showed that D-(?)-arabinose is a reversible, mixed-type inhibitor of tyrosinase ( -value? , ?M). Measurements of intrinsic fluorescence showed that D-(?)-arabinose induced obvious tertiary changes to tyrosinase (binding constant ?M?1, binding number ). This strategy of predicting tyrosinase inhibition based on specific interactions of aldehyde and hydroxyl groups with the enzyme may prove useful for screening potential tyrosinase inhibitors. 1. Introduction Tyrosinase (EC is a ubiquitous enzyme with diverse physiologic roles related to pigment production. It plays a central role in melanin synthesis in skin [1, 2], the browning of vegetables [3, 4], wound healing [5], and cuticle formation in insects [6, 7]. Structurally, tyrosinase belongs to the type 3 copper protein family [8, 9], which consists of two copper ions individually coordinated with three histidine residues at the active site. Tyrosinases are directly involved in several reactions and carry out catalytic steps such as the hydroxylation of tyrosine to 3,4-dihydroxyphenylalanine (DOPA), the oxidation of DOPA to DOPA quinone, and the oxidation of 5,6-dihydroxyindole to 5,6-dihydroxuquinone [10, 11]. In addition to its catalytic features, tyrosinase is distinctive from other enzymes because it displays various inhibition patterns. Tyrosinase inhibition has been extensively studied for cosmetic, medicinal, and agricultural purposes [12]. The tyrosinase mechanism is complex, and this enzyme can catalyze multiple reactions. Despite several reported crystallographic structures of tyrosinase, the 3D structure and architecture of the active site are not well understood [22, 23]. Mechanistic studies must involve a variety of computational methods and kinetic analysis to derive the structure-function relationship between substrates and ligands. The inhibitory effect of compounds with sugar backbones on tyrosinase are of great interest [20, 24, 25]. D-(–)-arabinose, a potential tyrosinase inhibitor, is an aldopentose with one
Co-Variation of Depressive Mood and Locomotor Dynamics Evaluated by Ecological Momentary Assessment in Healthy Humans
Jinhyuk Kim, Toru Nakamura, Hiroe Kikuchi, Tsukasa Sasaki, Yoshiharu Yamamoto
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0074979
Abstract: Computerized ecological momentary assessment (EMA) is widely accepted as a “gold standard” method for capturing momentary symptoms repeatedly experienced in daily life. Although many studies have addressed the within-individual temporal variations in momentary symptoms compared with simultaneously measured external criteria, their concurrent associations, specifically with continuous physiological measures, have not been rigorously examined. Therefore, in the present study, we first examined the variations in momentary symptoms by validating the associations among self-reported symptoms measured simultaneously (depressive mood, anxious mood, and fatigue) and then investigated covariant properties between the symptoms (especially, depressive mood) and local statistics of locomotor activity as the external objective criteria obtained continuously. Healthy subjects (N = 85) from three different populations (adolescents, undergraduates, and office workers) wore a watch-type computer device equipped with EMA software for recording the momentary symptoms experienced by the subjects. Locomotor activity data were also continuously obtained by using an actigraph built into the device. Multilevel modeling analysis confirmed convergent associations by showing positive correlations among momentary symptoms. The increased intermittency of locomotor activity, characterized by a combination of reduced activity with occasional bursts, appeared concurrently with the worsening of depressive mood. Further, this association remained statistically unchanged across groups regardless of group differences in age, lifestyle, and occupation. These results indicate that the temporal variations in the momentary symptoms are not random but reflect the underlying changes in psychophysiological variables in daily life. In addition, our findings on the concurrent changes in depressive mood and locomotor activity may contribute to the continuous estimation of changes in depressive mood and early detection of depressive disorders.
Anatomy of Scientific Evolution
Jinhyuk Yun,Pan-Jun Kim,Hawoong Jeong
Computer Science , 2014, DOI: 10.1371/journal.pone.0117388
Abstract: The quest for historically impactful science and technology provides invaluable insight into the innovation dynamics of human society, yet many studies are limited to qualitative and small-scale approaches. Here, we investigate scientific evolution through systematic analysis of a massive corpus of digitized English texts between 1800 and 2008. Our analysis reveals great predictability for long-prevailing scientific concepts based on the levels of their prior usage. Interestingly, once a threshold of early adoption rates is passed even slightly, scientific concepts can exhibit sudden leaps in their eventual lifetimes. We developed a mechanistic model to account for such results, indicating that slowly-but-commonly adopted science and technology surprisingly tend to have higher innate strength than fast-and-commonly adopted ones. The model prediction for disciplines other than science was also well verified. Our approach sheds light on unbiased and quantitative analysis of scientific evolution in society, and may provide a useful basis for policy-making.
The Relationship between Visual Satisfaction and Water Clarity and Quality Management in Tourism Fishing Ports  [PDF]
Lee-Hsueh Lee
Journal of Water Resource and Protection (JWARP) , 2016, DOI: 10.4236/jwarp.2016.88064
Abstract: Visual satisfaction of the tourists with a water body is strongly influenced by water clarity, which is in turn influenced by a number of water quality parameters. Visual satisfaction thus stands to benefit from having a water quality management tool that results in better water clarity. A Clarity Suitability Index of Water Quality (CSIWQ), derived from clarity suitability curves of selected water quality parameters, can allow estimation of optimal values for these parameters, while ensuring high visual satisfaction among tourists. The present study used sampling and survey methodologies to investigate water clarity and quality at five tourism fishing ports; simultaneously, tourists’ visual satisfaction with a water body was assessed through a questionnaire based on their perceptions. The relationship between tourists’ visual satisfaction and water clarity was found to be positive and strong, with water clarity having predictive power of 74.2%. The study showed that DO, BOD, TP, and SS were the most critical parameters for water clarity. A continued product approach of CSIWQ was found to be most appropriate for describing the relationship between water clarity and these four parameters. This enabled a CSIWQ Index value to be calculated. With a CSIWQ value of 0.6, water clarity would be more than 2.08 m, and tourists would experience very high satisfaction. CSI curves showed that DO would preferably be 9.0 mg/L, and BOD, TP, and SS less than 0.5 mg/L, 0.12 mg/L, and 45.0 mg/L, respectively. The model thus produced valuable insights for assessing and improving water quality and ensuring high levels of visual satisfaction among tourists in tourism fishing ports. This model identified only four parameters but could be improved by ensuring that other water quality parameters were included, to encourage an increase in the number of tourists and to include monitoring of more pollutant sources.
Appearance’s Aesthetic Appreciation to Inform Water Quality Management of Waterscapes  [PDF]
Lee-Hsueh Lee
Journal of Water Resource and Protection (JWARP) , 2017, DOI: 10.4236/jwarp.2017.913103
The appearance of the water is just one aspect of a waterscape that can be appreciated aesthetically. Water appearance is affected by water clarity and water colour. Here, an aesthetic assessment model of waterscape was suggested. In the model, water clarity and colour have direct effects, whereas water quality and phytoplankton biomass have indirect effects, on tourists’ aesthetic assessment of water bodies. The preferred water colour is aquamarine to blue, regardless of depth of clarity. Water colour ranges from pastel yellow to yellow-green are not favoured by tourists. Four water-quality parameters were correlated with water clarity and phytoplankton biomass. The coefficient of indirect effect of river pollution index on tourists’ aesthetic valuation of aquamarine to blue water colour was -0.457, and for pastel yellow to yellowgreen, it was -0.209. The research results showed observation of water colour could not only reflect waterscape aesthetic value, but also serve as a guide of judging water quality, and the status of phytoplankton benefited to simplify the process of water-quality management for waterscape.
Abdominal Fat Reduction through Cryolipolysis  [PDF]
Doyeop Lee, Kyurae Lee
Journal of Biosciences and Medicines (JBM) , 2018, DOI: 10.4236/jbm.2018.69005
Abstract: Although several studies showed the efficacy and safety from this procedure, the comparative assessment of adipose tissue by cryolipolysis has not been studied until now. Therefore we investigated the quantitative change of cross sectional areas of abdominal SAT (subcutaneous adipose tissue) and VAT (visceral adipose tissue) following cryolipolysis. A prospective study for twelve subjects with a single session of cryolipolysis on abdomen was performed. We assessed for their height, weight, and waist circumferences, body contours by photographs, and the cross sectional areas of visceral and subcutaneous adipose tissues were measured at umbilicus level by computerized tomography for 2 months. The cross sectional areas in SAT reduced from 243.3 ± 24.7 to 238.5 ± 40.7 cm2 at 2 months post-treatment. Those of VAT reduced from 141.3 ± 46.4 to 125.1 ± 42.8 cm2 at 2 months post-treatment. Cross sectional areas of VAT, and waist circumferences were significantly reduced by 16.2 cm2, 4.1 cm respectively. Additionally visual improvement without unexpected adverse events was noted. In conclusion a single session cryolipolysis demonstrated to reduce visceral adipose tissue as well as waist circumferences tissue for 2 months. Further controlled study would be needed to evaluate for reduction of visceral adipose tissue by cryolipolysis.
Exponential Ergodicity and β-Mixing Property for Generalized Ornstein-Uhlenbeck Processes  [PDF]
Oesook Lee
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.21004
Abstract: The generalized Ornstein-Uhlenbeck process is derived from a bivariate Lévy process and is suggested as a continuous time version of a stochastic recurrence equation [1]. In this paper we consider the generalized Ornstein-Uhlenbeck process and provide sufficient conditions under which the process is exponentially ergodic and hence holds the expo-nentially β-mixing property. Our results can cover a wide variety of areas by selecting suitable Lévy processes and be used as fundamental tools for statistical analysis concerning the processes. Well known stochastic volatility models in finance such as Lévy-driven Ornstein-Uhlenbeck process is examined as a special case.
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