• 한국수학교육학회지시리즈D:수학교육연구
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• 제17권2호
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• pp.79-97
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• 2013

This paper reports findings from a survey of senior secondary school students' epistemological conceptions of mathematics with the adaption of the instrument of the "Conceptions of Mathematics" - Inventory in China. The survey included a sample of 414 Grade 10 students, 441 Grade 11 students, and 400 Grade 12 students from three provinces. Descriptive statistics, one-way ANOVA, and T-test were employed to analyze data in this study. It was found that senior secondary school students mainly focused on objectivity and reality of mathematics, without highlighting the characteristics of sociality, subjectivity, and creativity of mathematics. In addition, besides gender differences, differences were identified among students from different grades, different areas, taught by teachers with different teaching experience and experience in using reformed curriculum.

• 한국전산유체공학회지
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• 제8권2호
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• pp.8-15
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• 2003

Three nonlinear κ-ε models with the wall function method are applied to the fully developed turbulent flow in a triangular subchannel of a bare rod bundle. Typical predicted quantities such as axial and secondary velocities, turbulent kinetic energy and wall shear stress are compared in details both qualitatively and quantitatively with both each other and experimental data. The nonlinear κ-ε models by Speziale[1] and Myong and Kasagi[2] are found to be capable of predicting accurately noncircular duct flows involving turbulence-driven secondary motion. The nonlinear κ-ε model by Shih et aL.[3] adopted in a commercial code is found to be unable to predict accurately noncircular flows with the prediction level of secondary flows one order less than that of the experiment.

• 한국항공운항학회지
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• 제16권4호
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• pp.12-19
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• 2008

GIOVE-B is the second experimental Galileo satellite for the Galileo In-Orbit Validation, which was launched by a Soyuz/Fregat rocket departing from the Baikonur cosmodrome in Kazakhstan on 27 April and now operated successfully. This paper presents the results obtained from processing of the E5a signal transmitted from the GIOVE-B. The acquisition and tracking of the data and pilot channels are performed by the E5a software receiver implemented by ETRI. Moreover, the paper suggests the GIOVE-B E5a-I/E5a-Q secondary code, which is determined by analyzing the correlation output of the primary correlator using the primary code.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제20회 춘계학술대회 논문집
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• pp.23-26
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• 2003

2차 유동을 이용한 추력제어법은 추진노즐 벽면에 설치된 injection hole을 통해 유동을 초음속유동장으로 분산하여 추력을 제어하는 방법으로, 최근 추진시스템의 응용에서 많은 주목을 받고 있다. 본 연구에서는 수치해석 방법을 이용하여 SITVC 유동장을 상세히 연구한다. 수치계산에는 3차원, 압축성 Navier-Stokes방정식이 적용되었으며, 그 결과는 이전의 유용한 실험결과와 비교한다. 본 수치해석 결과로부터 2차 유동의 유입에 의해 야기되는 충격파와 추진노즐로부터 방출된 제트구조를 상세하게 가시화한다.

• 생약학회지
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• 제47권3호
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• pp.217-221
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• 2016

Endophytic fungi have yielded a variety of secondary metabolites so far. In the course of the project to find bioactive secondary metabolites from cultures of endophytic fungi, an isolate of Arthrinium phaeospermum (JS 0567) was selected for chemical investigation. A large scale culture of this strain in rice media was extracted with an organic solvent and the extract was subjected to a serious of chromatography, which led to six metabolites. Their chemical structures were elucidated as 2,3,6,8-tetrahydroxy-1-methylxanthone(1), 2,3,4,6,8-pentahydroxy-1-methylxanthone(2), 3,4,6,8-tetrahydroxy-1-methylxanthone(3), 3,6,8-trihydroxy-1-methylxanthone(4), 2,4,2',4',6'-pentahydroxy-6-methylbenzophenone(5), and 5,7-di hydroxy-3-methylphthalide(6) on the basis of spectroscopic data. To the best of our knowledge, this is the first study on the secondary metabolites from Arthrinium phaeospermum.

• 한국수학교육학회지시리즈A:수학교육
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• 제46권4호
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• pp.357-369
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• 2007

Teachers and students' knowledge of zero was investigated through data collected from 16 preservice secondary mathematics teachers and 20 gifted secondary school students. Results showed that these teachers and students had an inadequate knowledge about zero. They exhibited a reluctance to accept zero as an attribute for classification, confusion as to whether or not zero is a number, and stable patterns of computational error. Although leachers and researchers have long recognized the value of analyzing student errors for diagnosis and remediation, students have not been encouraged to take advantage of errors as learning opportunities in mathematics instruction. The article suggests using errors as springboards for inquiry in action, discusses its potential contributions to mathematics instruction by analyzing students and preservice teachers errors related to zero.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.919-924
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• 2005

Fretting-wear caused by turbulence excitation for KSNP(Korea standard nuclear power plant) steam generator is investigated numerically. Secondary sides density and normal velocity are obtained by the thermal-hydraulic data of the steam generator. Because nonlinear finite element analysis is complex and time consuming, work rate is estimated by using linear analysis for simple straight 2-span tube. Wear volume and depth by using work rate calculation are estimated. Span length, secondary side fluid density and normal velocity are adopted to study the effects on the fretting-wear by turbulence excitation. When secondary sides density and normal velocity is increased, It turns out that secondary side density and normal gap velocity are very important paramater for fretting-wear phenomena of the steam generator.

• ETRI Journal
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• 제39권4호
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• pp.558-569
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• 2017

In this study, a non-preemptive M/G/1 queueing model of a spectrum handoff scheme for cognitive wireless networks is proposed. Because spectrum handoff gives secondary users an opportunity to carry on their transmissions, it is crucially important to determine the actions of primary users. In our queueing model, prioritized data traffic is utilized to meet the requirements of the secondary users. These users' packets are categorized into three different priority classes: urgent, real-time, and non-real time. Urgent data packets have the highest priority, while non-real time data packets have the lowest priority. Riverbed (OPNET) Modeler simulation software was used to simulate both reactive and proactive decision spectrum handoff schemes. The simulation results were consistent with the analytical results obtained under different load and traffic conditions. This study also revealed that the cumulative number of handoffs can be drastically decreased by exploiting priority classes and utilizing a decent spectrum handoff strategy, such as a reactive or proactive decision-based strategy.

• Transactions on Electrical and Electronic Materials
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• 제14권2호
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• pp.94-100
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• 2013

The elements B, P and As can each be implanted in silicon; for the fabrication of integrated semiconductor devices and the wells in CMOS (complementary metal oxide semiconductor). The implanted range due to different implanted species calculated using TRIM (Transport of Ions in Matter) simulation results was considered. The profiles of implanted samples could be measured using SIMS (secondary ion mass spectrometry). In the comparison between the measured and simulated data, some deviations were shown in the profiles of MeV implanted silicon. The Moliere, C-Kr, and ZBL potentials were used for the range calculations, and the results showed almost no change in the MeV energy region. However, the calculations showed remarkably improved results through the modification of the electronic stopping power. The results also matched very well with SIMS data. The calculated tolerances of $R_p$ and ${\Delta}R_p$ between the modified $S_e$ of TRIM and SIMS data were remarkably better than the tolerances between the TRIM and SIMS data.

• 재활복지
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• 제22권4호
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• pp.83-102
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• 2018

본 연구는 척수손상이 고령이 됨에 따라 만성질환과 2차 합병증에 미치는 요인을 알아봄으로써 효율적으로 관리와 예방에 관한 기초적인 자료를 제공하고자 한다. 대상자는 2013년 4월부터 2018년 4월까지 S병원에 입원한 척수손상 200명 대상으로 하였다. 의무기록 조사를 통해 만성질환인 고혈압, 당뇨, 간염, 결핵과 2차 합병증으로 폐렴, 기립성저혈압, 욕창, 부종, 자율신경반사항진, 심부정맥 혈전증, 이소성골화증, 중추성통증, 경직(상지/하지), 근 골격계 통증, 변비, 구축, 우울증, 골절, 고칼슘혈증, 불면증, 신장결석, 신경인성 방광 및 장, 비요로감염, 비만, 골다공증, 폐혈증, 수면무호흡, 요로감염의 발생유무를 조사하였다. 연구 결과 50세 미만보다 50세 이상 척수손상이 만성질환 및 2차합병증에 영향을 미치는 요인들로 나타났다. 50세 이상의 만성질환 유병 오즈비는 고혈압 11.8배, 당뇨 6.7배이며, 2차합병증 유병 오즈비는 골다공증 7.5배, 폐렴 5.2배, 신경인성통증 0.4배로 나타났다. 고령척수손상의 만성질환 및 2차합병증의 지속적인 관리와 서비스의 필요성을 시사하고, 향후 대상자의 확대와 다양한 특성을 포함한 연구가 이루어줘야 할 것이다.