• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.300-309
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• 2017

A spacecraft obtains a reaction momentum required for an orbit correction and an attitude control by exhausting a combustion gas through a small thruster in space. If the exhaust plume collides with spacecraft surfaces, it is very important to predict the exhaust plume behavior of the thruster when designing a satellite, because a generated disturbance force/torque, a heat load and a surface contamination can yield a life shortening and a reduction of the spacecraft function. The purpose of the present study is to ensure the core technology required for the spacecraft design by analyzing numerically the exhaust gas behavior of the 10 N class bipropellant thruster for an attitude control of the spacecraft. To do this, calculation results of chemical equilibrium reaction between a MMH for fuel and a NTO for oxidizer, and continuum region of the nozzle inside are implemented as inlet conditions of the DSMC method for the exhaust plume analysis. From these results, it is possible to predict a nonequilibrium expansion such as a species separation and a backflow in the vicinity of the bipropellant thruster nozzle.

• School Mathematics
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• v.6 no.1
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• pp.1-19
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• 2004

Recently, we have been listening such a words, that is, the crisis of public education through the mass communication such as newspaper or broadcasting. This means that we didn't have an enough opportunity to think it over about good education programme which the education of school can be normalized or the design of curriculum in the current problems such as overcrowded class, teacher and poor finance which is not still solved. As we know, it is true that the older generation is familiar with the rote learning which was under the control of behaviorism for about three hundred years. Fortunately, The 7th curriculum which had made public by the ministry of education on 30 Dec. 1997 have changed so many things such as real life based or activity based and so on. But it still leaves something to be desired in reflecting the demand of teachers of field. Taking into account this real situation, I have wondered how they run curriculum and how math learning programme of lower grade is different with ours in New Zealand, etc and so I had tried to find some suggestive points through the comparison of curriculum and text between Korea and New Zealand. But, if we want to compare all the strands of curriculum between two countries, it is too global and so in this paper, we deal with only number and operations(number), measurement, figure(geometry), equation and patter(algebra), probability and statistics(statistics) which are dealt with more comparatively in the lower grade of primary school. Because the main purpose of this paper is a comparison and analysis of the curriculum and math learning program of the lower grade in the primary school between two countries and so we compare global characteristics of education system and curriculum between two countries, at first and then we dealt with the very core part of the content of New Zealand curriculum within the ranges of level 1, 2 and 3 and global characteristics of learning program simultaneously.

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.75-89
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• 2005

D. K. LEE, J. S. LEE, B. J. LEE, H. S. LEE, Y. J. KIM, S. B. PARK, J. P. JOO. Plantar foot pressure analysis during golf swing motion using plantar foot pressure measurement system. Korean Journal of Sport Biomechanics, Vol. 15, No. 1, pp. 75-89, 2005. In this study, weight carrying pattern analysis and comparison method of four foot region were suggested. We used three types of club(driver, iron7, pitching wedge). This analysis method can compare between top class golfer and beginner. And the comparison data can be used to correct the swing pose of trainee. If motion analysis system, which can measure the swing speed and instantaneous acceleration at the point of hitting a ball, is combined with this plantar foot force analysis method, new design development of golf shoes to increase comfort and ball flight distance will be available. 1. Address acting, forces concentrated in rare foot regions and lateral foot of right foot. Back swing top acting, relatively high force occurred in medial forefoot region of left foot and forefoot region of right foot. Impact acting, high force value observed in the lateral rarefoot region of left foot and medial forefoot region of right foot. Finish acting, force concentration observed on the lateral region and rarefoot region of left foot. 2. Forces were increased in address of right foot with clubs length increased. All clubs, back swing top acting, high force value observed in the lateral forefoot region of right foot. All clubs, in impact, high force value observed in the lateral rarefoot region of left foot and medial forefoot region of right foot. Finish acting, force concentration observed on the rarefoot region in driver and lateral foot region in iron on left foot. 3. Right foot forces distribution were increased in address, back swing top and left foot force distribution were increased in impact, finnish

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1621-1621
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• 2001

The quality of sugarcane grown on the NE Australian tropical coast ($16^{\circ}$15'- $18^{\circ}$15' S Lat.) has declined markedly in the past seven years. This has been linked to dilution of mill-supply cane with increasing levels of non mature-stalk material consisting of leaves and sucker culms. The prime research objective was to examine the transition from the pre-harvest, in-field crop to harvested material sent for processing, in terms of quality and crop fraction proportions. A secondary objective was to quantify the effects of preharvest-season crop habit and culm condition on crop quality. Ten quadrat samples from each of 54 random crop sites (17 in 1999 and 37 in 2000), covering a wide range of variables (cultivar, crop class, and edaphic, topographic, climatic, and temporal factors) were collected immediately before harvest. Samples were partitioned into four fractions:- sound and unsound mature stalks (culms), sucker culms, and extraneous matter (leaves). Material harvested from each site was sampled and partitioned into four fractions:- sound and unsound billets (culm pieces), culm-spindle pieces, and leaf. In 2000, before harvest, 14 additional sites were sampled monthly, on three occasions, from March - June. Erect and non-erect culms were divided into sound and unsound classes. All samples were disintegrated and presented to a remote reflectance module of a scanning spectrophotometer using the BSES large cassette module. Near infra-red spectroscopic (NIS) analyses were developed for the rapid determination of quality components (Brix, commercial cane sugar (CCS), fibre, moisture, and polariscope reading). Calibrations for three material groups (culm (n = 639), non-culm (n = 496), and combined) were developed for all components using the 1999 data set. Two sub-sets (n = 178, and 190) of about 10% of the preharvest-season and harvest populations scanned in 2000 also were subjected to full routine laboratory analyses. The 1999 combined calibrations were excellent, but the culm calibrations produced consistently lower standard errors. Non-culm calibrations were marginally better than the combined for only CCS and pol. reading. Analysis of the 2000 culm data with calibrations using all 1999 and 2000 culm data resulted in better predictions relative to the 1999 culm calibrations. This also was true for the combined calibrations. Assessment of quality components in pre- and post-harvest sugarcane using NIS calibrations was more cost effective than using routine laboratory techniques. Outcomes from this NIS-facilitated research will have important economic consequences for the Australian sugarcane industry. Potential CCS present in mature culms is being discounted by dilution with leaves and sucker culms, threatening farm viability. The results question the efficacy of current harvesting technology. The CCS of harvested cane is improved only marginally over that of the in-field crop. Current harvesting technology requires either supplementary, innovative pre-mill processing or a design revolution to improve mill-supply cane quality, and therefore whole of industry economics. NIS-facilitated analyses, before the harvest season, highlighted the benefits of growing erect, sound crops. Loss of CCS then, can be minimized only by a combination of crop improvement and agronomic solutions, applied as part of sound on-farm management.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2007.05a
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• pp.55-68
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• 2007

디자인 패턴은 새롭게 만들어 지는 것이 아니라 기존의 검증된 지식, 관용법, 원칙들을 체계화한 것이다. 다시 말하면 디자인 패턴은 특정한 문제를 해결하기 위한, 검증된 설계 방법에 이름을 붙인 것이다. 그러므로 적절한 디자인 패턴 사용은 1) 개발자들간의 원활한 의사소통에 도움을 주며, 2) 하급자가 고급기술을 쉽게 익힐 수 있도록 할 수 있다. 3) 또한 사용된 디자인이나 아키텍처를 재사용할 수 있도록 하고, 4) 만들어진 시스템의 유지 보수를 보다 쉽게 할 수 있는 등의 장점을 얻을 수 있다. 반면에 필요하지 않은 곳에 까지 디자인패턴을 사용하게 되면 소프트웨어를 복잡하고, 유지보수도 어렵게 만들 수 있다. 디자인 패턴의 분류는 수 많은 패턴을 비슷한 속성을 지닌 그룹들로 조직화 하는 것이다. 이는 개발자가 특정 문제에 맞는 디자인 패턴을 쉽게 선택 할 수 있도록 도와 줄 뿐만 아니라, 디자인 패턴의 주요특성을 빠르게 이해하고 간파 할 수 있게 한다. 그래서 Beck 이 디자인패턴을 소개한 이후 GoF, Buschmann, Grand, Antoy 등은 디자인 패턴을 단순히 열거를 통해 소개하지 않고, 각자의 기준에 따라 체계적으로 분류하여 패턴을 설명 하고 있다. 본 연구는 객체지향 설계의 근본 개념인 Polymorphism (Inclusion Polymorphism) 과 '객체 지향 소프트웨어 설계 원칙' 그리고 이 근본 원칙들이 UML 클래스 다이어그램에 나타나는 구조적 특정에 의거해 디자인 패 턴 해석을 수행 하였다. 본 연구의 목적은 1) 객체지향의 근본 원칙으로 표현 되는 패턴과 2) 설계자의 전문적 인 Art를 포함하고 있는 패턴으로 분류하는데 있다.3: 재미는 용이성을 통해 채택의도에 정의 영향을 미친다. 가설4: 유용성은 채택의도에 정의 영향을 미친다. 가설5: 용이성은 채택의도에 정의 영향을 미친다. 가설6: 용이성은 유용성에 정의 영향을 미친다. 본 연구의 대상은 자발적으로 이러닝을 채택할 수 있는 대학생을 대상으로 하였고, 설문 데이터 분석을 통한 실증연구를 수행하였다. 분석방법으로는 PLS 분석도구를 사용하였다. 분석결과 가설6을 제외하고는 모두 유용한 것으로 입증되었다.97)은 배움의 용이성, 기억의 용이성, 오류, 효율성, 만족성으로 분류하고 있고(Nielsen, 1997), Shneiderman(1998)는 효과성(직무시간, 배움의 시간), 효율성(기억의 지속시간, 오류), 만족도를 품질의 특성으로 분류하였다. 이와 같은 소프트웨어의 품질은 소프트웨어 계획, 개발, 성장과 쇠퇴의 모든 과정에 적용되며, 환경적 변화에 따라 사용자들의 정보욕구를 적절하게 반영하여 만족도를 높이 는 것이라고 요약할 수 있다. 그러나 현재까지 소프트웨어 품질 평가에 대한 연구들 은 보편적인 평가 항목들을 대상으로 측정하여 일반적인 품질기준을 제시하고 있고, 유사한 측정 내용들이 중복되어 있다. 이러한 경향은 산업별 특수성이 강한 소프트웨어에 대해서는 정확한 품질측정이 어려웠고, 품질측정에 대한 신뢰성을 떨어뜨리는 계기가 되었다. 이러한 한계를 극복하고자 나타난 방법론이 최종사용자들의 요구사항을 얼마나 적절하게 시스템에 반영했는지에 대한 사용성(Usability) 측정이다. 사용성에 대한 정의는 사용자들이 실질적으로 일하는 장소에서 직접 사용자들의 시스템 운용실태를 파악하여 문제점을 개선하는 것으로 요약할 수 있다. ISO9124-1

• KEPCO Journal on Electric Power and Energy
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• v.2 no.4
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• pp.531-536
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• 2016

The worldwide research and development for high-efficiency power generation system is progressing steadily because of the growing demand for reducing greenhouse gas emissions. Many countries have spurred the research and development of supercritical $CO_2$ power generation technology since 2000 because it has the advantage of compactness, efficiency, and diversity. Supercritical $CO_2$ power generation system can be classified into an indirect heating type and a direct heating type. As of now, most studies have concentrated on the development of indirect type supercritical $CO_2$ power generation system. In the United States, NREL(National Renewable Energy Lab.) is developing supercritical $CO_2$ power generation system for Concentrating Solar Power. In addition, U.S. DOE(Department of Energy) also plans to start investing in the development of the supercritical $CO_2$ power generation system for coal-fired thermal power plant this year. GE is developing not only 10MW supercritical $CO_2$ power generation turbomachinery but also the conceptual design of 50MW and 450MW supercritical $CO_2$ power generation turbomachinery. In Korea, the Korean Atomic Energy Research Institute has constructed the supercritical $CO_2$ power generation test facility. Moreover, KEPRI(Korea Electric Power Research Institute) is developing a 2MW-class supercritical $CO_2$ power generation system using diesel and gas engine waste heat with Hyundai Heavy Industries.

• 대한공업교육학회지
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• v.32 no.1
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• pp.93-116
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• 2007

The purpose of this study was to improve the academic achievement at the public practical center of technical high school in Busan. For this study, 1 class(31 students) in the second grade at "B"technical high school were selected and these students were divided into two groups. One is the experiment group which blended learning was applied to and the other is control group which traditional lecture method was applied to. Each group was divided into three sub-groups by the level of learning ability. Non-randomized control-group pretest-posttest design was applied for this experiment planning. The subject of experiment was the unit of "3D Modeling and Making NC code" in the textbook of "Application of Automatic System" applied by the public practical center of technical high school in Busan. On-line contents were developed and applied to the blended learning to control group. In order to analyze the test result, t-test with a significance level of 0.05 was carried out using SPSS 10.0. The results of this study was summarized as follows; First, as a result of the post test performed on the experiment and the control group, there was a significant difference between two groups, that was, the blended learning was more effective than the traditional lecture method in improving academic achievement. Second, blended learning was more effective than the traditional lecture method in the group of high-leveled and middle-leveled, but was little effective on the low-leveled group. Third, blended learning was more effective than the traditional lecture method in the functional domain, but was little effective in the cognitive domain and psychomotor domain.

• Journal of Korea Multimedia Society
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• v.2 no.2
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• pp.217-229
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• 1999

Framework is the set of interrelated classes, constructing reusable design in specific domain or set of abstracted classes, and defines common architecture among applications included in domain. Developers can reuse not only class code but also wide range of knowledge on domain by reusing framework. In this papers, we present COM(Component-Oriented Methodology) for the reuse of framework, and develop construction environment for framework and domain development. That is, domain is analyzed by input of domain knowledge on real world to create software based on component, and hotspot is identified through analyzed information, and redesigned(refactoring) by putting additional information on users and developers. After that, I will create domain framework and application framework depending on domain. In this Component-oriented methodology, information is searched, understood and extracted or composite through component-pattern library storage internally. Then this information is classified into the information on component and pattern respectively, and used as additional information in redesigning. With this, developer can obtain reusability, easiness and portability by constructing infrastructure environment that allow to register, update and delete component through Component Pattern Management System(CPMS) under the development environment which can be easily applied to his own application using multimedia component, in this thesis, CORBA(Common Object Request Broker Architecture) environment.

• Journal of Broadcast Engineering
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• v.12 no.2
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• pp.80-92
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• 2007

IPTV Services that is representative union service of broadcasting and telecommunication need guarantee of QoS, efficiency of multicasting, and hish bandwidth on the network. Because typical TDM based metro transport network was designed by transporting fixed voice traffic with stable and recovering method, it has a defect of bottleneck and a waste of bandwidth for acceptance of data traffic with burst feature and then all of data are treated equally at the transport network because it cannot classify between advanced high end service and best effort low end service. for completely resolving this kind of problem about increasing burst traffic and QoS issues, firstly we need to new design for transport network. This paper presents transformation method from TDM based metro transport network to packet based transport network and advantage and effectiveness of packet based transport network and also indicates technical factor and characters about method of packet transport system. As a result of research, the Packet Transport System, which is a transmission network for packet delivery, take in not only a specific character of legacy TDM but QoS, Multicast and high bandwidth, then, it is able to keep an effective bandwidth and a stabilized performance of packet transmissions. Additionally, if a fault be occurred on an optical link, the system is able to guarantee a differential QoS by an each service class using an algorithm to make certain of a traffic existence and contain a protective mechanism.

• Journal of Science Education
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• v.34 no.2
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• pp.193-202
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• 2010

This study investigated the impact of student-centered instructions on students' academic achievement in science and on their attitudes toward science. Participants included 208 middle school students. The pre- and post-test control group design was employed. The control group was designed to have traditional instructions while experimental group 1 was applied both student-centered instructions and traditional instructions, and experimental group 2 was applied student-centered instructions only. The chaper of "Stimulus and Response" was selected for this study, and students were treated for 15 hours. Data were analysed using ANOVA. Results indicated that student-centered instruction had a significant effect on students' academic achievement(p<.01). The improvement of achievement through student-centered lesson is neither depending on genders nor previous academic achievement levels. Student-centered instruction also had a significant effect on students' attitudes toward science(p< .01). Only half of the class if a student-centered lessons and improve attitudes toward science could be. The improvement of the attitudes toward science through student-centered instruction is not depending on genders. But, student-centered instruction was more effective on the average student and the lower level students than the upper level students.