• Journal of Fisheries and Marine Sciences Education
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• v.28 no.5
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• pp.1388-1394
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• 2016

This paper presents a experimental study of two-phase flow boiling of FC-72 in multi channels. Flow boiling heat transfer coefficients are obtained with mass flux ranging from 152.9 to $353.9kg/m^2s$ and heat flux from 5.6 to $46.1kW/m^2$. The experimental results show that the heat transfer is governed by nucleate boiling mechanism in the low heat flux region. However, it is found that the effects of nucleate boiling and forced convection boiling are combined as the heat flux increases. A new correlation to predict the heat transfer coefficient is developed by using the dimensionless number such as Reynolds number, Weber number, boiling number. This correlation shows good predictive accuracy against the measured data.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.01a
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• pp.281-283
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• 2020

본 연구는 2015년 교육과정에 명시된 정보교과의 운영방침과 중등학교 소프트웨어 교육 현황을 분석하고, 이에 대한 문제점을 해결 할 수 있는 방안으로 창의적 문제 해결력을 통한 소프트웨어 교육 모형을 제안한다. 창의적 문제 해결력은 확산적 사고와 수렴적 사고를 통해 학생들이 문제 해결에 필요한 사고를 키울 수 있는 모형이다. 이에 본 논문에서는 컴퓨팅 사고력을 가진 창의·융합 인재 육성이라는 소프트웨어의 교육 목표를 달성하기 위해 기존의 CPS모형과 CT의 요소간의 유사점을 확인하고 이를 바탕으로 새로운 CPS-SW 모형을 제안한다. CPS-SW 모형으로 컴퓨팅 사고력과 창의적 문제해결력을 키울 수 있으며, 이를 통해 미래 사회에 필요한 인재육성을 위한 소프트웨어 교육의 발전에 기여하고자 한다. 또한 CPS-SW 모형을 적용할 수 있는 프로그램과 학생들이 창의적 문제해결력을 키울 수 있는 학습에 대한 연구가 필요할 것으로 예상한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.45-52
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• 2016

The purpose of this study was to investigate the meaning of conflict experience in cooperative learning activities of pre-service early childhood teachers. The subjects were 85 pre-service early childhood teachers in W university. The data were collected through unstructured interviews and journal writings of the participants. The study results were as follow. First, pre-service early childhood teacher's conflict experiences in cooperative activity are team meeting, fair participation and evaluation, and conflict of the personal relations. Second, pre-service early childhood teacher's conflict resolution experiences in cooperative activity are autonomy of the team meeting time, reflective thinking, sentimental support, recognition of others, and solving problems by the time spending together. Third, the meanings of conflict experience in cooperative activity are formation of felt responsibility, self-growth through consideration of others, reciprocity, and recognition of the meaning of cooperation.

• The Korean Journal of Ecology
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• v.14 no.4
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• pp.379-398
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• 1991

In order to investigate the ecotypic variations of pulsatilla koreana nakai distributed in korea, 8 local populations of the plant were selected in accordance with latitude and compared on the differences of leaf shape, elongstion, stomatal distribution and dhlorophyll content. The incised angle of the plant is 38。32' in cheju, showing a great difference as compared with 23。77'-30。 32' of the other sites. as to the incised rate, mt. togyu and cheju representsed relatively high values of 49.04% and 48.21% the parted leaved individuals were only observed along the warm current coastal area including cheju, sokcho and sunchon and were 54(62.8%), 2(2.5%) and 3(3.3%) in the sites, respectively. Especially, the individuals consisting of only parted learves were 5(5.8%) in cheju alone and none of the other sites showed such individuals at all. So p. cernua distributed in cheju and p. koreana in inland area can be considered to beecotypic variations of the same species from the upper investigations. According to the elongations of leaf and rachis, the local populations could be classified into 3 types, such as warm current coastal area type(cheju,sunchon and sokcho),southern inland area type(andong, chungju and mt. togyu)and central inland ara type(mt. komdan and hongchon). The dentate numbera of 39.80-43.73 in the warm current area were also different from those of 87% in mt.togyu and 15% in hongchon, while opposite leaflets account for 100% in the other sites. The content of chlorophyll ranged from 0.609 mg/g. d.w.(cheju)to 0.924 mg/g.d.w.(hongchon), showing an increasing trends as the latitudes grow higher. The number of stomata on the low epidermis is much larger than that on the upper epidermis in the whole area. But both aspects showed an increasing tendency, too as the latitude becomes higher.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.444-448
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• 2005

This paper presents a developing procedure of the CAN-based real-time simulator for car body control, aiming at replacing the actual W/H (Wiring Harness) and J/B(Junction Box) couple eventually. The CAN protocol, as one kind of field-bus communication, defines the lowest 2 layers of the ISO/OSI standard, namely, the physical layer(PL) and the data link layer(DLL), for which the CSMA/NBA protocol is generally adopted. For CPU, two PIC18Fxx8x's are used because of their built-in integration of CAN controller, large internal FLASH memory (48K or 64K), and their costs. To control J/B's and actuators, 2 controller boards are separately implemented, between which CAN lines communicate through CAN transceivers MCP255. A power motor for washing windshield, 1 door lock motor, and 6 blink lamps are chosen for actuators of the simulator for the first stage. For the software architecture, a polling method is used for the fast global response time despite its slow individual response time. To improve the individual response time and to escape from some eventual trapped-function loops, High/Low ports of the CPU are simply used, which increases the stability of the actuator modules. The experimental test shows generally satisfactory results in normal transmitting / receiving function and message trace function. This simulator based on CAN shows a promising usefulness of lighter, more reliable and intelligent distributed body control approach than the conventional W/H and J/B couple. Another advantage of this approach lies in the distributed control itself, which gives better performance in hard real-time computing than centralized one, and in the ability of integrating different modules through CAN.

• Journal of the Korean Chemical Society
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• v.58 no.6
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• pp.649-657
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• 2014

The purpose of this study was to develop a teaching strategy focused on science writing and to investigate its effects on enhancing students' problem solving ability. A teaching strategy using science writing enhancing problem solving ability (REWS model) was designed. The REWE model consisted of four stages: 1) Sensing and Stating of Scientific Problem by Reading (R stage), 2) Exploring Problem (E stage) 3) Explaining by Writing (W stage), 4) Integrated problem-solving (S stage). 135 10th grade of students were assigned to one experimental group and one control group. Students in the experiment group were taught by REWE model. Students in control group were taught by traditional lecture-based instructions. The program was implemented over a semester. The results indicated that the experimental group presented statistically meaningful improvement in critical thinking necessary to solve problems (p<.05). This study suggests that science writing can be effective for improvement of problem solving ability.

• Bulletin of the Korean Mathematical Society
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• v.52 no.5
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• pp.1433-1443
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• 2015

Catenoid and Riemann's minimal surface are foliated by circles, that is, they are union of circles. In $\mathbb{R}^3$, there is no other nonplanar example of circle-foliated minimal surfaces. In $\mathbb{R}^4$, the graph $G_c$ of w = c/z for real constant c and ${\zeta}{\in}\mathbb{C}{\backslash}\{0}$ is also foliated by circles. In this paper, we show that every circle-foliated minimal surface in $\mathbb{R}$ is either a catenoid or Riemann's minimal surface in some 3-dimensional Affine subspace or a graph surface $G_c$ in some 4-dimensional Affine subspace. We use the property that $G_c$ is circle-foliated to construct circle-foliated minimal surfaces in $S^4$ and $H^4$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05d
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• pp.82-85
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• 2003

산업의 고도화 및 환경오염의 문제로 1970년대부터 실리콘고무를 이용한 애자의 사용이 시도되기 시작되었다. 그로 인해 실리콘 고무의 표면열화에 대한 수많은 연구가 현재까지 행해지고 있다. 그러나 고온성 형압즉방식으로 제작하는 유기애자의 경우 제조시 발생할 수 있는 내부보이드에 대한 연구는 미흡한 현실이다. 이에 본 연구에서는 실리콘고무의 내부보이드의 형태변화에 따른 전기적열화특성을 연구하기 위하여 3층으로 적층시킨 실리콘 고무의 중간층에 임의적으로 4가지형태의 내부보이드를 성형하여 전압을 변화시키면서 방전전류 및 방전전력을 측정하였다. 그 결과, 보이드의 존재로 방전전류 및 방전전력의 증가를 볼 수 있었으며, 보이드형상의 내부각이 좁을수록 방전전류 및 방전전력값이 커지는 것을 볼 수 있었다.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.3
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• pp.81-89
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• 2012

This paper presents a set of controlled simulated statical and engineering mechanical experiments accessible via the virtual world environment (VWE) and virtual physics lab S/W. Online courses of the university offering courses and/or programs online are growing and the number of students want education in ways which fit their personal places, e-learning is becoming more important and ubiquitous each year. In this study, first of all, question is rather 'How do we execute the learning effectiveness of e-learning courses?' than 'Why does they need e-learnig or VW-learning?'. In particular, is it possible to effectively teach mechanical engineering courses online? The answer was 'No'. So, there is little research on many of these questions. And another important question is 'Is e-learning cost effective?'. For the answer, This research provided that an instructional design model is used to 'How to think and apply the Newtonian forces' in the virtual physics lab S/W. Collected data from student are administered in the spring semester when students studied 'Introduction to Bio-resources and Systems Engineering'. Results show that a cadre of students can take highly interactively physical properties of mechanical engineering in the virtual laboratory environment. Those show that VWE is greater than that of a similar real world presentation or experimental lab, since most of students are delighted to modify and retry modeling works in the VWE.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.220-223
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• 2003

This paper is aimed at determining the e-field distribution by apply voltage of air void, which can be generate air void in the XLPE cable for ultra high voltage. E-field distribution had an effect in XLPE due to the type and position of void, compared and studied. This method of analysis is based on the quasi-static electromagnetic 3D simulation program by boundary element method (BEM): Applied AC 3[kV], discretization of 2000 elements, 4 angular periodicity, The result of experiment indicate that E-field distribution appeared the highest levels on the void position of electrode 2[nm] outer boundary and shape of the smallest inner angle in the void. This will serve to explain the XLPE cable degradation studied of possible, connected cable variation of position and shape of void effects to e-field concentration.