• Title/Summary/Keyword: RHA

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Simulation study on the nonlinear evolution of EMIC instability

  • Rha, Kicheol;Ryu, Chang-Mo;Yoon, Peter H.
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.2
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    • pp.119.2-119.2
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    • 2012
  • Charged particle energization is an outstanding problem in space physics. This paper investigates the nonlinear dynamics of Alfve'n-cyclotron waves accompanying particle heating processes and the drift Alfv'en-cyclotron (or EMIC) instability associated with a current disruption event on 29 January 2008 observed with THEMIS satellite by means of a particle-in-cell simulation. The simulation shows that the drift Alfv'en-cyclotron instabilities are excited in two regimes, a relatively low frequency mode propagating in a quasi-perpendicular direction while the second high-frequency branch propagating in a predominantly parallel propagation direction, which is consistent with observation as well as earlier theories. It is shown that parametric decay processes lead to an inverse cascade of Alfv'en-cyclotron waves and the generation of ion-acoustic waves by decay instability. It is also shown that the nonlinear decay processes are accompanied by small perpendicular heating and parallel cooling of the protons, and a pronounced parallel heating of the electrons.

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철갑소이탄에 의한 전투시스템 내 적재포탄의 순간화재에 관한 전산해석

  • Lee, Seung-Cheol;Jeon, U-Cheol;Lee, Hae-Pyeong;Lee, Heon-Ju
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 2013.11a
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    • pp.208-209
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    • 2013
  • 본 연구에서는 철갑소이탄이 장갑을 관통한 후 전투시스템 내의 적재포탄(고폭탄 또는 추진제)에 피탄되었을 때 순간화재 발생확률에 대해 전산해석을 수행하였다. 장갑은 RHA 재질로 설정하였고, 장갑 두께를 5~30 mm까지 5 mm씩 증가시키며 전산해석을 실시하였다. 고폭탄은 COMPB, TNT, PBX가 사용되었으며 추진제는 ANB가 사용되었다. 본 해석은 Autodyn 프로그램을 사용하였으며, 순간화재 발생 여부를 해석하기 위해 Lee-Tarver ignition and growth model을 사용하였다. 해석 결과, 철갑소이탄이 고폭탄 TNT와 PBX에 피탄되었을 때, 순간화재 발생확률이 모두 100%를 나타내었으며, 고폭탄 COMPB의 경우, 0.8~0.08%로 나타났다. 추진제 ANB의 순간화재 발생확률은 3.8~3.6%로 나타났다.

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Free Play Activities in the Curricula of Childcare Centers and Teachers' Perceptions of Play (보육과정에서의 자유놀이 현황과 교사의 놀이인식)

  • Rim, Hyo-Shin;Rha, Jong-Hay
    • Journal of the Korean Home Economics Association
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    • v.49 no.2
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    • pp.27-36
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    • 2011
  • This study dealt with free play activities in the curricula of childcare centers in Daejeon area. 29 teachers from 21 day care centers were interviewed individually to obtain an understanding of teachers perceptions and conflicting views about play activity in the context of different day care curricula. The data were analysed qualitatively, using categorization and key word classification, frequency analyses and chi-squared tests. The results were as follows: (1) play-oriented curricula included sufficient play time and planned play activities in terms of the children's development. Children's freedom in play, optimum intercession by teachers, and interrelating activities between activity areas were included. In mixed curricula, children's freedoms were limited in many cases, and interrelating play between activity areas was hardly found. Formal lesson-oriented curricula resulted unplanned play activities and teachers' passive intercession of play. (2) Most teachers believed that play activities were more important to a child's development than formal lessons.

Movement Play Program of for the Child with Mental Retardation (정신지체아의 운동놀이 프로그램)

  • Rha Ki-Yong
    • The Journal of Korean Physical Therapy
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    • v.14 no.2
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    • pp.116-132
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    • 2002
  • In the management of the child with mental retardation, the physical therapist is challenged to use various skills. The many complex and persistent difficulties encountered by retarded children often require innovative methods physical therapy. These methods must incorporate not only he basic principles of physical therapy, but also an understanding of the teaching and learning as they relate to the mentally retarded person. Movement Play needs to parents and other professionals requires not only technical expertise on the part of the therapist, but also psychosocial skills and the ability to be a sensitive listener and teacher. We can help the mentally retarded child strive to attain goals in life.

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A Case Report of Idiopathic Precocious Puberty in Two Children (특발성 성조숙증으로 진단받은 환아 2례에 대한 증례보고)

  • Lee, Hye Lim;Yoo, Hwa Seung;Park, Seung Chan
    • The Journal of Pediatrics of Korean Medicine
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    • v.31 no.1
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    • pp.74-81
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    • 2017
  • Objectives The purpose of this study is to report the case of precocious puberty in two children treated by taking herbal medicine. Methods Two patients diagnosed with precocious puberty were prescribed Jogyeongseongjang-tang and were observed the effect of treatment on height, body weight, body composition, sex hormone test. Results During the treatment period, rapid progression of puberty was inhibited, and slow changes in sex hormones and steady growth were achieved. Conclusions This study showed the long-term effects of herbal medicine in treating precocious puberty, but further studies should be conducted for scientific validation.

A Study of Decreasing Noise and Vibration for a Light Rail Transit (경량철도 소음.진동의 저감 대책에 관한 연구)

  • Kim, Dong-Gi;Park, Jong-Bok;Park, Kwang-Hyun;Rha, Sang-Ju
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.53-56
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    • 2004
  • A light rail transit would be one of effective means to solve a traffic problem of the city. Noise and vibration originated from light railway, however, would be another problem. This study focuses on the method of decreasing noise and vibration for a light railway, and comprises track condition, driving condition, linear condition, vehicle condition and civil engineering structure condition. For decreasing noise and vibration in an track, long rail laying and low vibration track laying would be good methods. The result of this study proves that improving the track wold be the most economical and valid method for decreasing noise and vibration for light railway.

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INDUSTRIAL STATUS OF DRY PLATING AS AN ALTERNATIVE TO WET PLATING PROCESS IN KOREAN SURFACE FINISHING INDUSTRY

  • Kwon, Sik-Chol;Baek, Woon-Sung;Lee, Gun-Hwan;Rha, Jong-Joo
    • Journal of the Korean institute of surface engineering
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    • v.32 no.3
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    • pp.253-256
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    • 1999
  • Wet plating has been initiated and developed as a major surface finishing technology as of the long customized and highly productive process until now. As the external compression by virtue of the environmental preservation becomes stricter, there has been new move to adapt dry plating line instead of conventional wet plating one in domestic surface finishing industry. Dry plating, so-called, plasma surface technology has been developed in semiconducting industry and becomes a key technology to be useful as an alternative to wet plating in surface finishing industry. The historical progress of domestic surface finishing industry was outlined with the background on the adaptation of three dry plating processes-plasma spraying, plasma nitriding and ion plating. The present status of domestic industrial activity was covered on major alternative to wet plating.

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The Long-Term Outcome and Rehabilitative Approach of Intraventricular Hemorrhage at Preterm Birth

  • Juntaek Hong;Dong-wook Rha
    • Journal of Korean Neurosurgical Society
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    • v.66 no.3
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    • pp.289-297
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    • 2023
  • Technological advances in neonatology led to the improvement of the survival rate in preterm babies with very low birth weights. However, intraventricular hemorrhage (IVH) has been one of the major complications of prematurity. IVH is relevant to neurodevelopmental disorders, such as cerebral palsy, language and cognitive impairments, and neurosensory and psychiatric problems, especially when combined with brain parenchymal injuries. Additionally, severe IVH requiring shunt insertion is associated with a higher risk of adverse neurodevelopmental outcomes. Multidisciplinary and longitudinal rehabilitation should be provided for these children based on the patients' life cycles. During the infantile period, it is essential to detect high-risk infants based on neuromotor examinations and provide early intervention as soon as possible. As babies grow up, close monitoring of language and cognitive development is needed. Moreover, providing continuous rehabilitation with task-specific and intensive repetitive training could improve functional outcomes in children with mild-to-moderate disabilities. After school age, maintaining the level of physical activity and managing complications are also needed.

Human Visual Intelligence and the New Territory of Educational Technology Research

  • RHA, Ilju
    • Educational Technology International
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    • v.8 no.1
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    • pp.1-16
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    • 2007
  • The general aim of this article is to explicate what can be researched in our field based on the new understanding on the ability of human visual intelligence. To follow this aim, three key discussions were followed. The first is to explain why the human visual intelligence research is so important in our field and how it was neglected. The basic orientations of the research questions used in its framing and in answering are reviewed. After reviewing traditional research orientations, as the second discussion, alternative, more useful perspective for thinking about human visual intelligence is suggested. And the possibility of contribution for the future research in general is discussed. In doing so, human visual intelligence was defined in rather practically oriented ways rather than theoretically oriented ones. More practical perspectives were suggested. The third discussion is to show how to use the alternative perspectives of human visual intelligence in the areas of educational technology research. It was hoped that the article lays out conceptual groundwork for generation of educational technology research frameworks which can be used for the research conduct, reproduction and sharing by adopting practically oriented views on human visual intelligence as a new territory of educational technology research.