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Search Results: 1 - 10 of 15529 matches for " Il Yun "
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An Analysis of Variable-Speed Wind Turbine Power-Control Methods with Fluctuating Wind Speed
Yun-Su Kim,Il-Yop Chung,Seung-Il Moon
Energies , 2013, DOI: 10.3390/en6073323
Abstract: Variable-speed wind turbines (VSWTs) typically use a maximum power-point tracking (MPPT) method to optimize wind-energy acquisition. MPPT can be implemented by regulating the rotor speed or by adjusting the active power. The former, termed speed-control mode (SCM), employs a speed controller to regulate the rotor, while the latter, termed power-control mode (PCM), uses an active power controller to optimize the power. They are fundamentally equivalent; however, since they use a different controller at the outer control loop of the machine-side converter (MSC) controller, the time dependence of the control system differs depending on whether SCM or PCM is used. We have compared and analyzed the power quality and the power coefficient when these two different control modes were used in fluctuating wind speeds through computer simulations. The contrast between the two methods was larger when the wind-speed fluctuations were greater. Furthermore, we found that SCM was preferable to PCM in terms of the power coefficient, but PCM was superior in terms of power quality and system stability.
The Relation Between Diagrams of a Knot and Its Unknotting Number
Kang-Il Ri,Yun-Ho An,Chang-Il Rim
Mathematics , 2013,
Abstract: The unknotting number is the classical invariant of a knot. However, its determination is difficult in general. To obtain the unknotting number from definition one has to investigate all possible diagrams of the knot. We tried to show the unknotting number can be obtained from any one diagram of the knot. To do this we tried to prove the unknotting number is not changed under Riedemiester moves, but such a proposition is not correct. Reidemeister II move can change unknotting number. See Nakanishi-Bleiler example. So this article is withdrawn.
Three-Armed Trials Including Placebo and No-Treatment Groups May Be Subject to Publication Bias: Systematic Review
Yun Hyung Koog, Seo Ryang We, Byung-Il Min
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0020679
Abstract: Background It has been argued that placebos may not have important clinical impacts in general. However, there is increasing evidence of a publication bias among trials published in journals. Therefore, we explored the potential for publication bias in randomized trials with active treatment, placebo, and no-treatment groups. Methods Three-armed randomized trials of acupuncture, acupoint stimulation, and transcutaneous electrical stimulation were obtained from electronic databases. Effect sizes between treatment and placebo groups were calculated for treatment effect, and effect sizes between placebo and no-treatment groups were calculated for placebo effect. All data were then analyzed for publication bias. Results For the treatment effect, small trials with fewer than 100 patients per arm showed more benefits than large trials with at least 100 patients per arm in acupuncture and acupoint stimulation. For the placebo effect, no differences were found between large and small trials. Further analyses showed that the treatment effect in acupuncture and acupoint stimulation may be subject to publication bias because study design and any known factors of heterogeneity were not associated with the small study effects. In the simulation, the magnitude of the placebo effect was smaller than that calculated after considering publication bias. Conclusions Randomized three-armed trials, which are necessary for estimating the placebo effect, may be subject to publication bias. If the magnitude of the placebo effect is assessed in an intervention, the potential for publication bias should be investigated using data related to the treatment effect.
Fabrication of Biochips with Micro Fluidic Channels by Micro End-milling and Powder Blasting
Dae Jin Yun,Tae Il Seo,Dong Sam Park
Sensors , 2008, DOI: 10.3390/s8021308
Abstract: For microfabrications of biochips with micro fluidic channels, a large number of microfabrication techniques based on silicon or glass-based Micro-Electro-Mechanical System (MEMS) technologies were proposed in the last decade. In recent years, for low cost and mass production, polymer-based microfabrication techniques by microinjection molding and micro hot embossing have been proposed. These techniques, which require a proper photoresist, mask, UV light exposure, developing, and electroplating as a preprocess, are considered to have some problems. In this study, we propose a new microfabrication technology which consists of micro end-milling and powder blasting. This technique could be directly applied to fabricate the metal mold without any preprocesses. The metal mold with micro-channels is machined by micro end-milling, and then, burrs generated in the end-milling process are removed by powder blasting. From the experimental results, micro end-milling combined with powder blasting could be applied effectively for fabrication of the injection mold of biochips with micro fluidic channels.
Fabrication of Biochips with Micro Fluidic Channels by Micro End-milling and Powder Blasting
Dae Jin Yun,Tae Il Seo,Dong Sam Park
Sensors , 2008,
Abstract: For microfabrications of biochips with micro fluidic channels, a large number of microfabrication techniques based on silicon or glass-based Micro-Electro-Mechanical System (MEMS) technologies were proposed in the last decade. In recent years, for low cost and mass production, polymer-based microfabrication techniques by microinjection molding and micro hot embossing have been proposed. These techniques, which require a proper photoresist, mask, UV light exposure, developing, and electroplating as a preprocess, are considered to have some problems. In this study, we propose a new microfabrication technology which consists of micro end-milling and powder blasting. This technique could be directly applied to fabricate the metal mold without any preprocesses. The metal mold with micro-channels is machined by micro end-milling, and then, burrs generated in the end-milling process are removed by powder blasting. From the experimental results, micro end-milling combined with powder blasting could be applied effectively for fabrication of the injection mold of biochips with micro fluidic channels.
Mesh Simplification Using the Edge Attributes
Yun Il Dong,Choo Kyowoong,Lee Sang Uk
EURASIP Journal on Advances in Signal Processing , 2002,
Abstract: This paper presents a novel technique for simplifying a triangulated surface at different levels of resolution. While most existing algorithms, based on iterative vertex decimation, employ the distance for error metric, the proposed algorithm utilizes an edge criterion for removing a vertex. An interior angle of a vertex is defined as the maximum value of all possible angles formed by combinations of edges connected to a vertex. Since the surface curvature examined with the interior angle provides more information for decision of vertex removal than the conventional distance measure, the proposed algorithm can approximate the surface with less computation. The height of a triangle, which is formed by the pair of edges, is also used for an additional constraint. The computational complexity can thus be greatly alleviated to logarithmic scale from the exponential scale required for the conventional algorithms, while yielding the comparable error level.
Content Authoring and Cloud System Implementation for Smart Learning  [PDF]
Hyun-Seo Hwang, Jin-Tae Park, Kyeong-Taek Seo, Jun-Soo Yun, Il-Young Moon, Oh-Young Kwon, Byeong-Jun Kim
Journal of Computer and Communications (JCC) , 2015, DOI: 10.4236/jcc.2015.35017
Abstract:

In this paper, we implement a content authoring and cloud system for cloud-based smart cloud learning. With the advent of the smartphone and mobile devices such as tablets, the educational paradigm is also changing. Was using the computer to aid in the learning e-learning started in ICT education are evolving Over the variety, in recent years, combines smart learning and social learning, cloud-based smart devices in e-learning the concept of Smart Cloud Smart Education Services Learning was gives rise to the term. Smart Cloud and free running is always the knowledge content uploaded by anyone, anywhere, can also be shared with other users. A terminal and location, without limitations on time, are continuously available to the environment of a high- quality knowledge content was coming through a variety of smart media, open educational content platform is built over the level of the possible conditions than e-learning. In this paper, we develop applications and Web sites that can provide authored content for smart cloud learning. In addition, we have built the cloud for content management and the website that can share content with other users. In the future, should wish to study a way that can provide customized services over the learner analysis based on big data technology.

Inhibition of Endoplasmic Reticulum Stress Improves Mouse Embryo Development
Jin Yu Zhang, Yun Fei Diao, Hong Rye Kim, Dong Il Jin
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040433
Abstract: X-box binding protein-1 (XBP-1) is an important regulator of a subset of genes during endoplasmic reticulum (ER) stress. In the current study, we analyzed endogenous XBP-1 expression and localization, with a view to determining the effects of ER stress on the developmental competency of preimplantation embryos in mice. Fluorescence staining revealed that functional XBP-1 is localized on mature oocyte spindles and abundant in the nucleus at the germinal vesicle (GV) stage. However, in preimplantation embryos, XBP-1 was solely detected in the cytoplasm at the one-cell stage. The density of XBP-1 was higher in the nucleus than the cytoplasm at the two-cell, four-cell, eight-cell, morula, and blastocyst stages. Furthermore, RT-PCR analysis confirmed active XBP-1 mRNA splicing at all preimplantation embryo stages, except the one-cell stage. Tunicamycin (TM), an ER stress inducer used as a positive control, promoted an increase in the density of nuclear XBP-1 at the one-cell and two-cell stages. Similarly, culture medium supplemented with 25 mM sorbitol displayed a remarkable increase active XBP-1 expression in the nuclei of 1-cell and 2-cell embryos. Conversely, high concentrations of TM or sorbitol led to reduced nuclear XBP-1 density and significant ER stress-induced apoptosis. Tauroursodeoxycholic acid (TUDCA), a known inhibitor of ER stress, improved the rate of two-cell embryo development to blastocysts by attenuating the expression of active XBP-1 protein in the nucleus at the two-cell stage. Our data collectively suggest that endogenous XBP-1 plays a role in normal preimplantation embryonic development. Moreover, XBP-1 splicing is activated to generate a functional form in mouse preimplantation embryos during culture stress. TUDCA inhibits hyperosmolar-induced ER stress as well as ER stress-induced apoptosis during mouse preimplantation embryo development.
The first Irish genome and ways of improving sequence accuracy
Young Seok Ju, Yun Joo Yoo, Jong-Il Kim, Jeong-Sun Seo
Genome Biology , 2010, DOI: 10.1186/gb-2010-11-9-132
Abstract: See research article: http://genomebiology.com/2010/11/9/R91 webciteIn the past 10 years, numerous human genomic variants have been discovered and catalogued, mostly through the efforts of the International HapMap project and personal genome studies [1]. Information on human genomic variants may serve as a valuable resource for developing personalized medicine because some of these variants could potentially predispose humans to complex diseases. The 2009 version (version 130) of the dbSNP database included approximately 13.9 million (13.9 M) single nucleotide polymorphisms (SNPs) and 4.5 M small insertions and deletions (indels). However, many issues need to be addressed before personalized medicine becomes a reality. These include an understanding of: the kind and number of variants that exist in the entire human genome; the number of populations and individuals needed to detect most, if not all, human genomic variants with efficiency and accuracy; the frequency of common and rare variants in an individual genome; and finally the number of variants that influence human diseases.Recent advancements in next-generation sequencing technology have dramatically decreased both the cost and the time required for sequencing [1]. Consequently, in the past few years, sequencing of individual genomes (personal genomes) has gained in popularity. Currently, whole-genome sequencing is thought to be the best way to detect human genomic variations because it could detect novel variants [2]. Excluding cancer genomes, so far at least 15 personal genomes have been sequenced and analyzed using various platforms (Figure 1). In this issue of Genome Biology, Tong and colleagues [3] present data on the first whole-genome sequence of an Irish person using the Illumina Genome Analyzer platform. As the authors [3] suggest, the Irish population could be a good candidate for genomic studies as it is isolated and located in the western fringes of Europe, and thus may possess many polymorphisms
Formation of ZnO Micro-Flowers Prepared via Solution Process and their Antibacterial Activity
Wahab Rizwan,Kim Young-Soon,Mishra Amrita,Yun Soon-Il
Nanoscale Research Letters , 2010,
Abstract: This paper presents the fabrication and characterization of zinc oxide micro-flowers and their antibacterial activity. The micro-flowers of zinc oxide composed of hexagonal nanorods have been prepared via solution process using precursor zinc acetate di-hydrate and sodium hydroxide in 3 h of refluxing time at ~90°C. The antibacterial activities of grown micro-flowers were investigated against four pathogenic bacteria namely S. aureus, E. coli, S. typhimurium and K. pneumoniae by taking five different concentrations (5–45 μg/ml) of ZnO micro-flowers (ZnO-MFs). Our investigation reveals that at lowest concentration of ZnO-MFs solution inhibiting the growth of microbial strain which was found to be 5 μg/ml for all the tested pathogens. Additionally, on the basis of morphological and chemical observations, a chemical reaction mechanism of ZnO-MFs composed of hexagonal nanorods was also proposed.
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