• Journal of Korean Elementary Science Education
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• v.33 no.4
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• pp.784-794
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• 2014

In this study, we operated science teacher learning community to enhance professionality of elementary science teachers. 8 participants with various background, which include their science content knowledge, teaching experience and beliefs about teaching, were involved in this study. Bales(1950)'s social interaction process framework was mainly used to understand the members' interaction, focusing particularly on process aspects not on contents aspects. The data analysis shows that the members in the science teacher learning community tried their best to maintain the positive reaction to other members in most occasions in the community meetings. On the other hand, there were also negative reaction process due to their different ideas and views, causing their emotional conflicts in some social relations and dialogical situations. Nevertheless, the results also imply that the dual reaction processes, which are positive and negative processes, are equally important to facilitate science teachers' professional knowledge and experience. The educational meanings are discussed in the aspects of science teacher education.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.631-636
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• 2007

An efficient obstacle avoidance algorithm is proposed in this paper to avoid dynamic obstacles using a collision vector while a tele-operated mobile robot is moving. For the verification of the algorithm, an operator watches through a monitor and controls the mobile robot with a force-reflection joystick. The force-reflection joystick transmits a virtual force to the operator through the Inter-net, which is generated by an adaptive impedance algorithm. To keep the mobile robot safe from collisions in an uncertain environment, the adaptive impedance algorithm generates the virtual force which changes the command of the operator by pushing the operator's hand to a direction to avoid the obstacle. In the conventional virtual force algorithm, the avoidance of moving obstacles was not solved since the operator cannot recognize the environment realistically by the limited communication bandwidth and the narrow view-angle of the camera. To achieve the dynamic obstacle avoidance, the adaptive virtual force algorithm is proposed based on the collision vector that is a normal vector from the obstacle to the mobile robot. To verify the effectiveness of the proposed algorithm, mobile robot navigation experiments with multiple moving obstacles have been performed, and the results are demonstrated.

• Proceedings of the Korean Reliability Society Conference
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• 2011.06a
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• pp.107-113
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• 2011

The windshield wiper consists of 4 parts: a blade, an arm, a linkage and a motor. The wiper blade makes contact with the windshield and is designed to be operated normally at an angle of 30~50 degrees to the front glass. If the contact pressure between the wiper blade and windshield surface is too high, noise and wear of the rubber will result. On the other hand, if the contact pressure is too low, the performance will do badly, since foreign substances such as dust and stains will not be removed well. The pressure and friction of the wiper blade has a great influence on its effectiveness in cleaning the front window. This is due to the contact of the rubber with the window. This paper presents the dynamic analysis method to estimate the performance of the flat type blade of the wiper system. The blade has a nonlinear characteristic since the rubber is an incompressible hyper-elastic and visco-elastic material. Thus, Structural dynamic analysis using a complex contact model for the blade is performed to find the characteristics of the blade. The flexible multi-body dynamic model is verified by the comparison between test and analysis result. Also, the optimization using the central composite design table is performed.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.165-170
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• 2000

Port State Control (PSC) is the inspection of foreign ships in national ports for the purpose of verifying th\ulcorner the condition of the ships and its equipments comply with the requirement of international conventions and the ship is manned and operated in compliance with applicable international laws. On the other hand, check items in PSC are nearly similar to periodical survey of Classification Societies, because they have the same background regarding safety and maritime pollution prevention. The purpose of this study is to develope computer-aided information systems for ship inspection item which is useful for effective implementation of Port State Control. For this work, the status of PSC is reviewed, and the related scheme of ship survey system in Classification Societies is investigated. On these bases, a computer software integrated database system and object-oriented technique is developed. The developed system is expected helpful to establish and maintain an effective system of Port State Control.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.3
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• pp.308-314
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• 2017

Jet pump in automotive fuel tank module is used to deliver fuel to fuel pump so that the pump is operated without aeration in suction side. In this study, three dimensional simulation model of jet pump is developed to understand performance variation over design parameters. Performance of jet pump is also investigated experimentally in terms of operating pressures. The experimental data is used to verify the three dimensional simulation model of jet pump. Verification results show that the three dimensional simulation model of jet pump is about 1% error with experiment. The simulations are conducted in terms of throat ratio and primary flow induction angle. As the throat ratio is increased, the flux ratio is trade-off at 3 times of throat diameter. On the other hand, as primary flow induction angle is increased, vapor pressure inside the nozzle is decreased. In summary, the results show that liquid jet pump has to be optimized over design parameters. Additionally, high velocity of induced flow is able to evolve cavitation phenomena inside the jet pump.

• Journal of Practical Engineering Education
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• v.12 no.1
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• pp.101-108
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• 2020

KOREATECH has operated a Co-op program called 'Industry Professional Practice (IPP)' that allows students to work full-time in relevant industries for at least four months since 2012, and also developed a systematic performance evaluation model on the basis of Kirkpatrick's four-stage assessment model. This study aims to share KOREATECH's Levels 3 and 4 evaluation results which are clearly what practitioners and academic investigators of cooperative education want to know the most. For this purpose, a questionnaire survey was conducted for KOREATECH graduates and their superiors to examine influence of IPP experiences on employment and job performance. A total of 730 alumni who graduated within last 5 years participated in the survey, with 213 (29.2%) having IPP experiences, and 162 superiors rated their subordinates on seven performance criteria. The analysis results were mixed. On the one hand, employment rate of IPP participants was 89.7%, compared to 86.8% of alumni without field experiences. Participants of the IPP program were more satisfied with their salary and felt less unfair about their career and promotion opportunities than alumni without field experiences. On the other, superiors rated their subordinates without IPP experiences slightly more positively than IPP participants in terms of job performance. These contrasting results are judged to show strengths and weaknesses of the IPP program at the same time. The limitations of the study and future research directions are discussed at the last part.

• Environmental Engineering Research
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• v.25 no.4
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• pp.554-560
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• 2020

This study focuses on nitrification through a biological aerated filter (BAF) that is filled with a zeolite medium at low concentrations of ammonia. The zeolite medium consists of natural zeolite powder. The BAF is operated under two types of media, which are a ball-type zeolite medium and expanded poly propylene (EPP) medium. Nitrification occurred in the zeolite BAF (ZBAF) when the influent concentration of ammonia nitrogen was 3 mg L-1, but the BAF that was filled with an EPP medium did not experience nitrification. The ammonia nitrogen removal efficiency of ZBAF was 63.38% and the average nitrate nitrogen concentration was 1.746 mg/L. The ZBAF was tested again after a comparison experiment to treat pond water, and municipal wastewater mixed pond water. The ZBAF showed remarkable ammonia-nitrogen treatment at low concentration and low temperature. During this period, the average ammonia nitrogen removal efficiency was 64.56%. Especially, when water temperature decreased to 4.7℃, ammonia nitrogen removal efficiency remained 79%. On the other hand, the chemical-oxygen demand (COD) and phosphorus-removal trends were different. The COD and phosphorus did not show as efficient treatment as the ammonia-nitrogen treatment.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.2
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• pp.1-10
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• 2003

The purpose of this study was to survey the status of the operation of site-based environmental education(EE) programs. This study surveyed 165 schools and organizations that operated site-based EE program in 2000 using a mail questionnaire and interviews. The response rate was 43%. The result indicated that awareness, participation, and attitude were considerably addressed, while knowledge and skills were addressed to a lesser degree. There were some difficulties in motivating students and in considering the developmental stage of participants. For programing the site-based EE, financial support and expert knowledge of EE were needed most of all. Learning materials for various and hand-on activities were also needed. The affective domain, such as awareness and attitude, showed marked improvement in the outcomes of the programs. Direct experience and sensitivity, connection with school education, regional characteristics were sufficiently addressed in the programs, while cultural aspects, fairness, originality, and accuracy were not. Flexibility in performing the programs and less rigidity of report on operations were needed. Through the discussion of the results, some improvements for the operation of site-based EE program were suggested.

• Journal of Korean Society on Water Environment
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• v.26 no.1
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• pp.140-147
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• 2010

In existing design method for aeration tank water temperature was considered as governing variable for applying safety factor. This study tried a few new approach of aeration tank design using SOUR at various temperature conditions. Specific substrate utilization rate (U) and specific oxygen uptake rate (SOUR) both were analyzed at various temperature and SRT. The laboratory scale reactor was operated on various temperature ($10^{\circ}C$, $20^{\circ}C$, $25^{\circ}C$) and SRT (5day, 10day, 20day, 30day). In this study, SOUR tended to increase with the temperature increased. On the other hand, SOUR tended to decrease when SRT increased from 5 days to 30 days. Empirical equations were obtained SOUR=a/SRT+b and $SOUR=(a/m){\cdot}U+(b-a(n/m))$ from the relationship between SRT, U and SOUR. Empirical equations shows the possibility as a new design method for the aeration basin.

• Journal of the Korean Society of Food Culture
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• v.15 no.3
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• pp.155-162
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• 2000

The purpose of this study was to analyse serving size, plate waste, and sensory evaluation on menu of university foodservice. This study was conducted in three restaurant of one university for 14 days, 1995. The serving size of food was measured by weighing machine. The plate waste of food was calculated by the aggregative selective plate waste measurement technique. Questionnaires of sensory evaluation were developed and hand-delivered at three restaurants. Rating criteria of sensory evaluation were appearance, taste, temperature, color, flavor, texture and overall quality. The plate waste of side dish were 35.5%, 42.5%, and 39.2% in A, B, and C restaurants. The plate waste of kimchi were 46.8%, 36.3%, and 55.9% in A, B, and C restaurants. So, university foodservice manager should concern quality of side dish and kimchi. The score of fried food in sensory evaluation was low. So, batch cooking was needed. The score of rice in sensory evaluation of C restaurants was very low. Therefore, steam ice cooker in C restaurants should be changed by gas automatic rice cooker.