• International Journal of Contents
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• 제12권2호
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• pp.49-57
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• 2016

This paper aims to explore instructional design of a cyber classroom for secondary students' basic English language competence. A paucity of support for low or under achieving students' English learning exists particularly at the secondary level. In order to bridge the gap, there has been demand for online educational resources considered to be an effective tool in improving students' self-directed learning and motivation. This study employs a comprehensive approach to instructional design for the asynchronous cyber classroom with the underlying premise that different learning theories can be applied in a complementary manner to serve different pedagogical purposes best. Gagné's conditions of learning theory, Bruner's constructivist theory, Carroll's minimalist theory, and Vygotsky's social cognitive development theory serve as the basis for designing instruction and selecting appropriate media. The ADDIE model is used to develop online teaching and learning materials. Twenty-five key grammatical features were selected through the analysis of the national curriculum of English, being grouped into five units. Each feature is covered in one cyber asynchronous class. An Integration Class is given at the end of every five classes for synthesis, where students can practice grammatical features in a communicative context. Related theories, pedagogical practices, and practical web-design strategies for cyber Basic English classes are discussed with suggestions for research, practice and policy to support self-directed learning through a cyber class.

• 대한인간공학회지
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• 제34권2호
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• pp.85-101
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• 2015

Objective: The purpose of this study was to develop and evaluate smart secondary controls using iPad for the drivers with physical disabilities in the driving simulator. Background: The physically disabled drivers face problems in the operation of secondary control devices that accept a control input from a driver for the purpose of operating the subsystems of a motor vehicle. Many of conventional secondary controls consist of small knobs or switches that physically disabled drivers have difficulties in grasping, pulling or twisting. Therefore, their use while driving might increase distraction and workload because of longer operation time. Method: We examined the operation time of conventional and smart secondary controls, such as hazard warning, turn signal, window, windshield wiper, headlights, automatic transmission and horn. The hardware of smart secondary control system was composed of iPad, wireless router, digital input/output module and relay switch. We used the STISim Drive3 software for driving test, customized Labview and Xcode programs for interface control of smart secondary system. Nine subjects were involved in the study for measuring operation time of secondary controls. Results: When the driver was in the stationary condition, the average operation time of smart secondary devices decreased 32.5% in the normal subjects (p <0.01), 47.4% in the subjects with left hemiplegic disabilities (p <0.01) and 38.8% in the subjects with right hemiplegic disabilities (p <0.01) compared with conventional secondary devices. When the driver was driving for the test in the simulator, the average operation time of smart secondary devices decreased 36.1% in the normal subjects (p <0.01), 41.7% in the subjects with left hemiplegic disabilities (p <0.01) and 34.1% in the subjects with right hemiplegic disabilities (p <0.01) compared with conventional secondary devices. Conclusion: The smart secondary devices using iPad for people with hemiplegic disabilities showed significant reduction of operation time compared with conventional secondary controls. Application: This study can be used to design secondary controls for adaptive vehicles and to improve the quality of life of the people with disabilities.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.312-317
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• 2000

High efficient steam turbine stage has been developed with the help of the 3-dimensional design tool. In this stage design, the compound leaned stacking method has been adopted to reduce the secondary flow loss of a turbine passage and to increase the performance efficiency for the turbine nozzles. And the turbine buckets have been designed with the quasi-3-dimensional turbomachinery blade design method. To verify the stage design, therefore, the 3-dimensional numerical simulation of a steam turbine stage was conducted. In this design, CFX-TASCflow was employed to predict the turbulent flow of a steam turbine stage. The analysis was performed in parallel calculation using the HP N4000 8 CPUs machine. The result showed CFX-TASCflow could be used as the 3-dimensional flow analysis tool of steam turbine design.

• 한국자동차공학회논문집
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• 제7권8호
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• pp.132-142
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• 1999

In this paper, a new formula for primary and secondary thrust of metal belt CVT is proposed considering variation of band tension, block compression and active arc for each of the primary and secondary pulleys. For the secondary thrust, effective friction coefficient is introduced considering the effect of flange deflection. Nondimensional primary and secondary thrust of the metal belt CVT by the new formula agree well with the experimental results except for low torque range, $0\;<\;{\lambda}\;<\;0.2$ at speed ration i = 1.0. The new formula can be used in design of the primary and secondary thrusts control system for the metal belt CVT.

• 한국자동차공학회논문집
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• 제11권6호
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• pp.73-79
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• 2003

The characteristics of NOx emission in multi fuel/air staged combustor have been experimentally studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is act as a pilot flame for the secondary combustion stage combustion zone, where most of fuel burns. Experiments were performed on a semi-industrial scale (thermal input 0.233 ㎿) in a laboratory furnace and Liquefied Petroleum Gas(LPG) was used as primary and secondary fuels. The study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, primary/secondary air ratio, primary swirl intensity and secondary swirl intensity for reducing NOx emission. The test demonstrated that NOx emission can be reduced by >70% in accordance with operating conditions.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.163-171
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• 2001

The characteristics of NOx emission in multi fuel/air staged combustor have been experimentally studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is act as a pilot Dame for the secondary combustion stage combustion zone, where most of fuel bums. Experiments were performed on a semi-industrial scale (thermal input 0.233 MW) in a laboratory furnace and Liquefied Petroleum Gas(LPG) was used as primary and secondary fuels. The study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, primary/secondary air ratio, primary swirl intensity and secondary swirl intensity for reducing NOx emission. The test demonstrated that NOx emission can be reduced by ${>}$70% in accordance with operating conditions.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1997년도 봄 학술발표회 논문집
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• pp.147-151
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• 1997

The dynamic characteristics of Control Element Drive Mechanism (CEDM) in Korea standard Nuclear Power Plant was reviewed as a secondary mass in a simplified two degree of freedom system, while the reactor vessel as a primary mass. The design improvement stratege to minimize each displacement amplitude of these primary and secondary masses was proposed. According to this stratege the designs of CEDM components, the shroud and the pressure housing, respectively, were changed using optimization technique.

• 한국전자통신학회논문지
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• 제10권7호
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• pp.781-786
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• 2015

본 논문은 과전류 경고회로의 신호를 나타내는 변류기를 설계하기 위해 관통형 변류기의 특성을 분석하고 손실을 고려한 최적 설계를 수행하였다. 관통형 변류기 코어의 크기는 2차측의 코일 턴수에 따라 결정된다. 우리는 코어에 코일을 감는 턴수에 따라 다르게 나타나는 전류 파형을 분석하였으며, 변류기 코어의 자속포화에 의한 비정현적인 파형을 개선하고자 2차측 코일 턴수와 부하저항과의 관계를 확인하였다. 또 코어의 외경은 유지하면서 내경 및 적층을 변화시켜 정밀도 개선 및 최적설계를 하였고, 이를 통하여 과전류 경고회로의 동작에 필요한 전류 값을 도출하였다.

• 대한기계학회논문집B
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• 제20권11호
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• pp.3573-3588
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• 1996

The flow through a centrifugal compressor impeller was calculated using the 3-dimensional Navier-Stokes solution method. A control volume method based on a rotating curvilinear coordinate system was used to solve the time-averaged Navier-Stokes equations, and a standard k-.epsilon. model was used to obtain eddy viscosity. Numerical results and experimental data were compared for the overall performance of the impeller, the pressure distributions along the shroud wall and the detailed flowfields at the design and off-design conditions, which showed good coincidence. The flow through the impeller is complex with the curvature of the streamlines and rotation. The development of secondary flows and the jet-wake flow characteristics, which is the main source of flow loss, was discussed. Calculation results show quite different patterns as the flow rate changes.

• 한국항공우주학회지
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• 제37권9호
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• pp.829-836
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• 2009

말굽와류로 대표되는 3차원 유동현상은 필연적으로 주유동에 대한 2차 유동의 형태로 발생되며, 유동손실을 유발하게 된다. 본 논문에서는 2차유동 손실을 일으키는 주요 요인중의 하나인 말굽와류의 강도를 감쇄시키기 위해 일반적인 날개 앞전에 설치한 판에 대해, 판의 설치 높이, 길이, 폭 및 두께 등의 형상변수를 설계변수로 정하여 이를 최적화하였다. 근사최적설계 기법을 이용 최적화를 수행하였으며, $FLUENT^{TM}$와 $iSIGHT^{TM}$를 이용하였다. 최적화 수행결과, 기준 모델의 경우보다 전압력 계수가 약 7.5% 감소하였다.