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Numerical and Experimental Investigations of Dynamic Stall

  • Geissler, Wolfgang;Raffel, Markus;Dietz, Guido;Mai, Holger
    • 한국전산유체공학회:학술대회논문집
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    • 2009.04a
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    • pp.19-19
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    • 2009
  • Dynamic Stall is a flow phenomenon which occurs on the retreating side of helicopter rotor blades during forward flight. It also occurs on blades of stall regulated wind turbines under yawing conditions as well as during gust loads. Time scales occurring during this process are comparable on both helicopter and wind turbine blades. Dynamic Stall limits the speed of the helicopter and its manoeuvrability and limits the amount of power production of wind turbines. Extensive numerical as well as experimental investigations have been carried out recently to get detailed insight into the very complex flow structures of the Dynamic Stall process. Numerical codes have to be based on the full equations, i.e. the Navier-Stokes equations to cover the scope of the problems involved: Time dependent flow, unsteady flow separation, vortex development and shedding, compressibility effects, turbulence, transition and 3D-effects, etc. have to be taken into account. In addition to the numerical treatment of the Dynamic Stall problem suitable wind tunnel experiments are inevitable. Comparisons of experimental data with calculated results show us the state of the art and validity of the CFD-codes and the necessity to further improve calculation procedures. In the present paper the phenomenon of Dynamic Stall will be discussed first. This discussion is followed by comparisons of some recently obtained experimental and numerical results for an oscillating helicopter airfoil under Dynamic Stall conditions. From the knowledge base of the Dynamic Stall Problems, the next step can be envisaged: to control Dynamic Stall. The present discussion will address two different Dynamic Stall control methodologies: the Nose-Droop concept and the application of Leading Edge Vortex Generators (LEVoG's) as examples of active and passive control devices. It will be shown that experimental results are available but CFD-data are only of limited comparison. A lot of future work has to be done in CFD-code development to fill this gap. Here mainly 3D-effects as well as improvements of both turbulence and transition modelling are of major concern.

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Water vapor in high-mass star-forming regions and PDRs: the Herschel/HIFI view

  • Choi, Yunhee;van der Tak, Floris F.S.;van Dishoeck, Ewine F.;Bergin, Edwin A.
    • The Bulletin of The Korean Astronomical Society
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    • v.40 no.2
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    • pp.42.2-43
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    • 2015
  • Massive stars play a major role in the interstellar energy budget and the shaping of the galactic environment. The water molecule is thought to be a sensitive tracer of physical conditions and dynamics in star-forming regions because of its large abundance variations between hot and cold regions. Herschel/HIFI allows us to observe the multiple rotational transitions of H2O including the ground-state levels, and its isotopologues toward high-mass star-forming regions in different evolutionary stages. Photodissociation regions (PDRs) are also targeted to investigate the distribution of water and its chemistry. We present line profiles and maps of H2O using data from two guaranteed-time key programs "Water In Star-forming regions with Herschel" and "Herschel observations of EXtra-Ordinary Sources". We analyze the temperature and density structures using LTE and non-LTE methods. We also estimate turbulent and expansion velocities, and abundance of water in the inner and outer envelopes using the 1D radiative transfer code. Around high-mass protostars we find H2O abundances of ~10-8-10-9 for the outer envelope and ~10-4-10-5 for the inner envelope, and expansion and turbulent velocities range from 1.0 km s-1 to 2.0 km s-1. The abundances and kinematic parameters of the sources do not show clear trends with evolutionary indicators. The Herschel/HIFI mapping observations of H2O toward the Orion Bar PDR show that H2O emission peaks between the shielded dense gas and the radicals position, in agreement with the theoretical and the observational PDR structure. The derived H2O abundance is ~10-7 and peaks at the depth of AV ~8 mag from the ionization front. Together with the low ortho-to-para ratio of H2O (~1) presented by Choi et al. (2014), our results show that the chemistry of water in the Orion Bar is dominated by photodesorption and photodissociation.

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The Literature Review of Music Therapy in the United States (음악요법에 관한 연구)

  • Lee, Won-Yu
    • Research in Community and Public Health Nursing
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    • v.11 no.1
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    • pp.245-261
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    • 2000
  • Based on the literature, status and role the music therapist in America was reviewed for this study. The process of developing a music therapy program in America suggests to us many things: In America, music therapists have sustained a mutually beneficial status with their clients for, over fifty years. Excellence in academic education and clinical training enable music therapists to continue to provide quality music therapy. The magnitude of change in to music therapy in the United States, however creates the challenge of providing real access to music therapy continues in the future. Music therapy is the use of music in the accomplishment of therapeutic aims: the restoration, maintenance, and improvement of mental and physical health. Music therapists work with individuals of all ages who require special services due to behavioral. social. learning, or physical disabilities. Employment may be in hospitals, clinics, day care facilities, schools, community mental health centers, substance abuse facilities, nursing homes, hospices, rehabilitation centers, correctional facilities, or private practices. The American Music Therapy Association (AMTA) was founded in 1998 as a result of a union between the American Association for Music Therapy (founded in 1971) and the National Association for Music Therapy(founded in 1950). Music therapists are highly qualified professionals who have completed approved degree programs and had clinical training in order to receive Board Certification(MT-BC), with the designation of Registered, Certified, or Advanced Certified Music Therapist(RMT. CMT - or ACMT). AMTA provides several mechanism for monitoring the quality of music therapy programs: Standards of Practice. a Code of Ethics, a system for Peer Review, a Judical Review Board, and an Ethics Board. According to the results of this study, the suggestions were as follows: 1. It is concluded that music therapy as a nursing intervention can be effective for the clients. 2. It is a great challenge to develope a music therapy program for nursing intervention however, it is also task and responsibility to further the development of nursing.

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The Design and Implementation of Restructuring Tool with Logical Analysis of Object-Oriented Architecture and Design Information Recovery (설계 정보 복구와 객체 지향 구조의 논리적 분석을 통한 재구성 툴 설계 및 구현)

  • Kim, Haeng-Gon;Choe, Ha-Jeong;Byeon, Sang-Yong;Jeong, Yeon-Gi
    • The Transactions of the Korea Information Processing Society
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    • v.3 no.7
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    • pp.1739-1752
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    • 1996
  • Software reengineering involves improving the software maintenance process and improving existing systems by applying new technologies and software tools. Software reengineering can help us understand existing systems and discover software components that are common across systems. In the paper, we discuss the program analysis and environment to assist reengineering. Program analysis takesan existing program as input and generates information about structured part and object-oriented part. It is used to restructure the information by extracting code through reengineering methodology. These restructuring informations with object-oriented archilccture are mapping prolog form to query by using direct reation and summary relation.

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Simplified Load Distribution Factor Equation for the Design of Composite Steel Girder Bridges (강합성교 설계를 위한 하중분배계수 간략식)

  • Chung, Wonseok
    • Journal of Korean Society of Steel Construction
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    • v.17 no.2 s.75
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    • pp.131-138
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    • 2005
  • The AASHTO wheel load distribution factor (LDF) equation has been with us since 1931 and has undergone minor modifications. In 1994, an entirely new procedure was introduced in the AASHTO LRFD code based on parametric studies and finite element analyses. However, this LDF equation involves a longitudinal stiffness parameter, the design of which is not initially known. Thus, an iterative procedure is required to correctly determine the LDF value. The increased level of complexity puts undue burden on the designer resulting in a higher likelihood for misinterpretation and error. In this study, based on current AASHTO LRFD framework, a new simplified equation is developed that does not require an iterative procedure. A total of 43 representative composite steel girder bridges are selected and analyzed using a finite element model.The new simplified equation produces LDF values that are always conservative when compared to those obtained from the finite element analyses and are generally greater than the LDF obtained using AASHTO LRFD specification. Therefore, the proposed simplified equation is expected to streamline the determination of LDF for bridge design without sacrificing safety.

Effective Safety Management by the Classification of Safety Standard (안전기준 분류에 따른 효과적 안전관리)

  • Lee, Hyun Woo;Lee, Young Jai
    • Journal of Korean Society of Disaster and Security
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    • v.6 no.3
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    • pp.35-42
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    • 2013
  • The purpose of this research is to systematize safety management for practical application through analysis and review of several safety standards currently in force among the statutes and rules regarding various safety accidents. Accordingly, the safety standard systems of Japan, US, and Germany were examined and a KOSAM entity relationship diagram (ERD) was drawn based on the ontology system. The ERD consists of the safety standard scope, safety management statute, safety management standard, safety management subjects, causes of safety accidents, and safety management organization entities. Next, each entity was assigned a code and finally a KOSAM safety management condition search screen was designed based on the ERD. This research is expected to bring an overall improvement in safety standard management and operation through safety standard DB construction and the execution of safety management system development.

A Research into Deconstructive Features in Visual Communication Design

  • Hong Dong-Sik
    • Archives of design research
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    • v.19 no.3 s.65
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    • pp.207-218
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    • 2006
  • 21st century is called digital and information era. The visual communication becomes more important than any other centuries. Visual communication design has been represented in varied images from ancient society up until the present time. Especially graphic design, which has experienced artistic upheaval from modernism and postmodernism, has been enabled to deliver messages in a more developed and sensuous appearances. Deconstructionist design wasn't well received by modernism, an advocate of practicality and effectiveness; however, as the beginning of subsequent postmodernism, it started to earn a warm welcome from a number of designers. Postmodernism made it possible for deconstruction to be a new paradigm appreciating neutral respect for varied expressions and designers' idiosyncrasy. Corresponding to this new trend, Edward Fella published his artwork 'Letters on America', which introduced a variety of vernacular design works in America. It was the result of years of research, and included materials which were not something completely new to field of communication design but rather symbolic, deconstructive images available everywhere around us. Deconstruction broke away from the previous modernism's unity and standards, and sought to achieve a new tensional deliverance. As a consequence, images were created in destructive and incomplete forms. Graphic design also complied with this new code and its advent fascinated the artists in the fields of advertising, editorial and poster designs. This paper contends that contemporary graphic design still maintains a deconstructive representation, examines its locality in design works from an aesthetic viewpoint, and researches theoretical approaches to deconstructionist and case studies conducted domestically. There has been incessant critical contradiction in terms of the heritage of deconstruction. I would like to present you with a moment in which you can struggle to decide whether it is a result of an effort to get away from modernism or an offspring of postmodernism.

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Generation of Hot Patent and it's Statistical Analysis (Hot Patent생성과 통계적 분석)

  • Kwon, Oh-Jin;Noh, Kyung-Ran;Lee, Bang-Rae;Hong, Sung-Hwa
    • Proceedings of the Korea Contents Association Conference
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    • 2009.05a
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    • pp.294-299
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    • 2009
  • The studies were conducted constantly to detect emerging technology, in order to make sustainable growth of business and to make development of future nations. But there were many controversies because definition of emerging technology might be dependent of the subject's viewpoint and because it might be different to a point of time that emerging technology is applied to the present or the future. This paper sets times of emerging technology to the present and defines emerging technology as patents significantly used in developing current technology. US Patents and patent citation data were gathered from 1976 to 2007. We constructed hot patents pools that were utilized actively in developing new technologies regardless of times. We built a mapping table from IPC classification code to WIPO 32 technology category and analysed a half-life cycle according to specific technology groups.

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Design and Implementation of RFID-based Airway Logistics System for Ubiquitous Environments (유비쿼터스 환경을 위한 RFID 기반의 항공 물류 시스템의 설계 및 구현)

  • Jang, Sung-Ho;Ma, Yong-Beom;Noh, Chang-Hyeon;Park, Yang-Jae;Kim, Kyo-Hyeon;Cha, Heung-Suk;Lee, Jong-Sik;Kim, Jea-Moung
    • Journal of the Korea Society of Computer and Information
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    • v.12 no.6
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    • pp.297-306
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    • 2007
  • Bar-code based airway logistics systems have many problems like freight loss and data management error due to semiskilled air-cargo process and individual information system. To solve these problems, this paper analyzed how to process an air-cargo practically and designed and implemented the RFID-based airway logistics system. This system has an information service system which manages data from RFID systems in realtime and provides a communication interface for data sharing. And, this system precesses data queries from capture applications and access applications to provide various services to users such as the freight track and trace service. Also, this system includes a H/H reader agent to integrate existing bar-cord systems. It allows us to realize automation and information-oriented air-cargo process and achieve improvement of air-cargo services with reduction of freight loss and management error.

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DEVELOPMENT AND EVALUATION OF THE MUON TRIGGER DETECTOR USING A RESISTIVE PLATE CHAMBER

  • Park, Byeong-Hyeon;Kim, Yong-Kyun;Kang, Jeong-Soo;Kim, Young-Jin;Choi, Ihn-Jea;Kim, Chong;Hong, Byung-Sik
    • Journal of Radiation Protection and Research
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    • v.36 no.1
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    • pp.35-43
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    • 2011
  • The PHENIX Experiment is the largest of the four experiments that have taken data at the Relativistic Heavy Ion Collider. PHENIX, the Pioneering High Energy Nuclear Interaction eXperiment, is designed specifically to measure direct probes of the collisions such as electrons, muons, and photons. The primary goal of PHENIX is to discover and study a new state of matter called the Quark-Gluon Plasma. Among many particles, muons coming from W-boson decay gives us key information to analyze the spin of proton. Resistive plate chambers are proposed as a suitable solution as a muon trigger because of their fast response and good time resolution, flexibility in signal readout, robustness and the relatively low cost of production. The RPC detectors for upgrade were assembled and their performances were evaluated. The procedure to make the detectors better was optimized and described in detail in this thesis. The code based on ROOT was written and by using this the performance of the detectors made was evaluated, and all of the modules for north muon arm met the criteria and installation at PHENIX completed in November 2009. As RPC detectors that we made showed fast response, capacity of covering wide area with a resonable price and good spatial resolution, this will give the opportunity for applications, such as diagnosis and customs inspection system.