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        검색결과 1,728

        1103.
        2004.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Since the teaching of English was introduced into the primary school as a required subject in 1997, no achievement test has been administered for the purpose of comparing English achievement of primary school students who are receiving private instruction with that of those who are not. The purpose of this study was to investigate what impact private instruction had on English achievement of third- and fourth-year students in the primary school. For this purpose, an English achievement test was developed based on the 7th national curriculum and two questionnaires were administered: one questionnaire among 743 third- and fourth-year primary school students and the other among 22 primary school teachers. The results showed that students who were receiving private instruction outperformed those who were not on the English achievement test and that teachers had difficulty in handling English class due to the discrepancy of overall English proficiency between tutored students and non-tutored students. The findings suggest that teacher training needs to be intensified to ensure quality English language teaching in the primary school.
        6,900원
        1105.
        2004.06 구독 인증기관 무료, 개인회원 유료
        The following paragraph is extracted from an email message written by a German medical doctor working in Papua New Guinea (PNG) since 1999. I was impressed the most by a 15-year-old boy who arrived out of the bush in a health center complaining about lower-right abdominal pain. Due to the possibility of an appendix infection, he had to be transferred to the hospital. But the sea was rough, and he had to wait for two days at the health center. Then a so-called banana boat, a boat with an outboard motor, brought him in a 6-hour trip to Vunapope [a town in PNG]. Even for healthy people such a trip with all the up and down is not a pleasure. As it turned out, the appendix had broken through and quite some pus had collected in his abdomen. In spite of the pain medication, the trip on the boat must have been hell for the boy, but he endured it courageously. The doctor regularly reports about her life and adventures in PNG to her friends and sponsors viaemail. The stories in her e-mail messages are often fascinating and sometimes heartbreaking. Life m PNG is far beyond what some of us can imagine. This article reports on information technology (IT) in PNG, particularly as it affects education and cultural development. The findings are based on data collected from the medical doctor and a school principal, both currently working in PNG. The purpose of the article is not to present sophisticated research results but to offer a glimpse of IT culture in PNG. It starts with a brief overview of IT in developing countries and then focuses on PNG.
        4,000원
        1110.
        2004.05 구독 인증기관 무료, 개인회원 유료
        The Charpy and Izod impact tests are the most prevalent techniques used to characterize the effects of high impulse loads on polymeric materials. An analysis method for rubber toughened PVC is suggested to evaluated critical dynamic strain energy release rates(Gc) from the Charpy impact tester was used to extract ancillary information concerning fracture parameters in additional to total fracture energies and maximum critical loads. The dynamic stress intensity factor KID was computed for varying amounts of rubber contents from the obtain maximum critical loads and also toughening effects were investigated as well. The fracture surfaces produced under low velocity impact for PVC/MBS composites were investigated by SEM. The results show that MBS rubber is very effective reinforcement material for toughening PVC.
        4,500원
        1111.
        2004.05 구독 인증기관 무료, 개인회원 유료
        The vertical impact crusher is the machine which could produce artifical sand similar to natural aggregates in the site of guarry and pits. FEM was used to analyse the stress and strength of the machine at high rotational speed. The test specimen was made from the same material as the shaft and tension tests were conducted. The Shaft under extreme conditions was analysed to determine maximum stress level and its location from the results. The maximum level of stress and its location could be predicted.
        4,000원
        1112.
        2004.04 구독 인증기관 무료, 개인회원 유료
        We developed the logical methods to analyze economic impacts of standardization and applied these analytical ways into performing this studies in micro and macro aspects. This study is performed through analysing foreign studies and results from surveys. The advanced methods performing standardization as a form of "korean standards" are suggested here. which are based on results of this study. The major consequences of this study are followings. The economic micro impact is that each company gets 604.5 millions won a year through performing KS A, F(discount rate 4.5%) and 1.46 trillions won is the macro economic impact through performing total KS A, F, which comes to 0.245% of GDP.
        4,300원
        1113.
        2004.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        랜덤동요된 조화가진력을 받는 임팩트시스템의 비선형거동을 개발된 반해석적절차에 의해 확률영역에서 분석하였다. 반해석적절차는 path-integral solution을 이용하여 임팩트시스템의 추계론적 미분방정식으로부터 구함으로 얻어진다. 결합확률밀도함수의 전개를 구하고 시스템의 비선형거동 특성인 혼돈거동에 대하여 분석하고 노이즈의 영향을 시간영역과 확률영역에서 알아보았다. 결과로부터 반해석적절차는 결합확률밀도함수를 통하여 임팩트시스템의 거동에 대한 정보를 제공하는 것을 알 수 있었다. 노이즈의 영향은 혼돈거동의 특성을 약화시키며 궁극적으로 사라지게 함을 알 수 있었으며 또한 혼돈거동의 특성이 상대적으로 높은 노이즈아래에서도 남아있는 것을 밝혔다. 결합확률밀도함수는 응답앙상블이 약정상과정임을 확인시켜 주었다.
        4,000원
        1114.
        2004.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper is to study the energy absorption characteristics of CF/Epoxy(Carbon Fiber/Epoxy Resin) laminated shell with the various curvatures subjected to transverse impact loadings under the low impact velocity in consideration of design of structural members for use of transportation machine, which are consisted of the characteristics of high stiffness, strength and lightweight. The curvature radius are associated with the energy absorption characteristics of CF/Epoxy laminated shell which is brittleness material. In all tests, maximum load of CF/Epoxy laminated plate is higher than that of laminated shell with curvature, but maximum deflection is lower. And then absorbed energy of laminated shell with curvature is higher than laminated plate(curvature radius is unlimited), As curvature radius is increased, the absorbed energy is increased in laminated shell with curvature.
        4,500원
        1118.
        2003.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 지수형 함수로 표현된 비선형 충격력을 받는 시스템의 동적 응답 정밀도를 향상시키고자 선형 충격력의 경우와 비교ㆍ검토하였다. Newmark 계열의 중앙법 알고리듬이 사다리꼴법과 같이 충격력이 없는 경우 모멘텀과 에너지 보존을 성립하도록 유도되었다. 중앙법, 사다리꼴법, 시간구간 종점 평가법((n+1)점 방법)을 선형 충격력에 적용하면 적분간격의 크기에 상관없이 보존성질을 만족하나, 비선형 충격력의 경우 모멘텀과 에너지 보존 상수값이 과소 또는 과대평가 되어졌다. 이러한 오차를 제거하고자 시간간격을 늘리면서 평가함수의 개수를 최소로 하는 다단계 방법중의 하나인 Simpson 1/3법을 사용하여 보존상수값의 정밀도를 향상시켰다. 아울러 유한회전을 포함한 유한운동을 해석할 때에도 제안된 알고리듬이 확정ㆍ적용될 가능성을 보여주고 있다.
        4,000원
        1119.
        2003.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Many of researches regarding mechanical properties of composite materials are associated with humid environment and temperature. Especially the temperature is a very important factor influencing the design of thermoplastic composites. However, the effect of temperature on impact behavior of reinforced composites have not yet been fully explored. An approach which predicts critical fracture toughness GIC was performed by the impact test in this work. The main goal of this work is to study the effect of temperature and span of specimen supports on the results of Charpy impact test for GF/PE composite. The critical fracture energy and failure mechanism of GF/PE composites were investigated in the temperature range of 60℃;to;-50℃ by the Charpy impact test. The critical fracture energy showed the maximum at the ambient temperature, and it tended to decrease as the temperature increased or decreased from the ambient temperature. The major failure mechanisms are the fiber matrix debonding, the fiber pull-out and/or delamination and the matrix deformation.n.
        4,000원