• The Korean Journal of Malacology
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• v.16 no.1_2
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• pp.31-34
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• 2000

A series of rearing experiments have been conducted to determine the growth and survival rate in accordance with body size in closed recirculating sea water system. The abalone, Sulculus aquatilis, spat of 10.24${\pm}$0.85 mm, 0.36${\pm}$0.l g and 24.9${\pm}$1.07 mm 2.07${\pm}$0.57 g in shell length and body weight were used in this study Ranges of water temperature and pH during the rearing period of 90 days were 10.0-24.2$^{\circ}C$ and 7.8-8.2, respectively. Dissolved oxygen during the experiment period was 6.13-7.21 ml/l and inorganic nitrate was 0.68-3.72 $\mu\textrm{m}$ in NH$_4$$\^$+/-N, 0.17-7.79 fm in NO$_2$-N and 0.4-11.52 $\mu\textrm{m}$ in NO $_2$-N, Growth in shell length and body weight of the spat in large group and small group at the end of the experiment were 30.80${\pm}$3.14 mm, 17.98${\pm}$2.61 mm and 3.20${\pm}$0.8 g, 0.36${\pm}$0.1 g, and survival rate of spat in large group and small group at the end of the rearing experiment were 96.0% and 90.0% , respectively.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.6
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• pp.12-20
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• 2008

Recent wireless communication technologies are envisioned as an innovative alternative to solve transportation problems. On ad hoc networks, as a wireless communication technology, nodes can communicate data without any infrastructure. In particular, vehicular ad hoc networks (VANETs), a specific ad hoc network applied to vehicles, enable vehicles equipped with a communication device to form decentralized traffic information systems in which vehicles share traffic information they experienced. This study investigated traffic information dissemination in a VANET-based traffic information system. For this study, an integrated transportation and communications simulation framework was developed, and experiments were conducted with real highway networks and traffic demands. The results showed that it took 3 minutes in the low traffic density situations (10 vehicle/lane.km) and 43 seconds in the high traffic density condition (40 vehicle/lane.km) to deliver traffic information of 5km away with 10% market penetration rate. In uncongested traffic conditions, information seems to be disseminated via equipped vehicles in the opposite direction. In congested traffic conditions, the sufficient availability of equipped vehicles traveling in the same direction reduces the chance to use vehicles in the opposing direction even though it is still possible.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4573-4579
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• 2014

In the 21st century, university education is changing from an objective knowledge and information to critical thinking and problem-solving ability. Moreover, university education should change rapidly towards a learner-centered educational environment because it has an educational goal to have college students experience authentic tasks they will be in charge of after graduation, and improves self-directed learning ability and cooperative learning ability. PBL is a pedagogical strategy for posing significant, contextualized, real world situations, and providing resources, guidance, and instruction to learners as they develop content knowledge and problem-solving skills. In problem based learning, the students collaborate to study the issues of a problem as they strive to create viable solution. For these advantages of PBL, the application of PBL in school has been enlarged. On the other hand, the application of PBL in engineering education has not been enlarged. To improve these instruction methods, the development or applications of new instructional methods will be needed. This study examined the PBL instructional design of a creative engineering design subject, which aims to foster talent. The PBL model developed in this study consists of Analysis, Design, Development, Implementation, and Evaluation. A plan of creative engineering design subject was developed based on PBL, and focused on the process of PBL. To determine the effects of this model, studies applying this instructional design to many lecturers should be implemented.

• The Journal of the Acoustical Society of Korea
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• v.35 no.3
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• pp.167-174
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• 2016

Underwater communication is difficult to increase the communication capacity because the carrier frequency is lower than that of radio communications on land. This is limited to the bandwidth of the signal under the influence of the characteristics of an ocean medium. As the high transmission speed and large transmission capacity have become necessary in the limited frequency range, the studies on MIMO (Multiple Input Multiple Output) communication have been actively carried out. The performance of the MIMO communication is lower than that of the SIMO (Single Input Multiple Output) communication because cross-talk occurs due to multiusers along with inter symbol interference resulting from the channel characteristics such as delay spread and doppler spread. Although the adaptive equalizer considering multi-channels is used to mitigate the influence of the cross-talk, the algorithm is normally complicated. In this paper, time reversal mirror technique with the characteristic of a self-equalization will be applied to simplify the compensation algorithm and relieve the cross-talk in order to improve the communication performance when the signal transmitted from two channels is received over interference on one channel in the same time. In addition, the performance of the MIMO communication based on the time reversal mirror is verified using data from the SAVEX15(Shallow-water Acoustic Variability Experiment 2015) conducted at the northern area of East China Sea in May 2015.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.83-92
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• 2013

An emerging learning method, flipped learning, has gained much interest lately due to its process involving prior study followed by the students' classroom involvement, which direction matches that of the current educational policy that emphasizes self-directed learning. This study investigated the concept of flipped learning and explored ways to develop instructional design models that utilize it. Flipped learning is not a model that has been recently developed, as it uses the format of blended learning with the introduction of a new concept of prior learning that allows students to learn in advance through online lessons and video clips related with the classroom content to be covered. During class time, individualized supplementary or in-depth study is conducted on the basis of the students' prior learning. The main considerations for designing flipped learning are a flexible classroom environment, a shift in learning culture, intentional classroom content, and educators equipped with professional capability. The research proposes the development of instructional design models for flipped learning pursuant to such concept and considerations. Through this research, the concept of flipped learning can be comprehended; furthermore, flipped learning can be utilized more effectively in the teaching and learning environment.

• Journal of the Korea Concrete Institute
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• v.26 no.1
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• pp.23-34
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• 2014

This study investigates the relationship between the performance of fresh and hardened Ultra-High Performance Concrete (UHPC) without heat treatment. The performance of fresh UHPC is determined by the slump flow test related to the fluidity of concrete mixtures, and the air content test. The variables of these tests are the water to binder ratio, superplasticizer dosages and volume fractions of steel fiber. Generally, insufficient fluidity and excessive air contents in concrete mixtures lead to the insufficient packing density related to the performance of harden concrete. The performance of hardened UHPC is determined by the compressive and flexural tensile tests. The results of the fresh UHPC tests show that there is the linear correlation between each variable and the slump flow diameter, and that the slump flow diameter is linearly decreased as the air content ratio increase. Using these results, the formula is developed to predict the fresh performance before mixing UHPC. The results of the hardened UHPC tests show that the hardened performance is not influenced by the air content ratio in the range of 3.2 to 4.2 per cent. However, the flexural tensile strength dominantly influenced by the volume fractions of steel fiber.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.3
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• pp.132-145
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• 2020

By coming of the 4th industrial revolution era, HD map have became a key infrastructure for determining precise location of autonomous driving in areas of futuristic cars, logistics and robots. Autonomous vehicles have became more dependent on HD map to determine the exact location of objects detected by various sensors such as LiDAR, GNSS, Radar, and stereo cameras as well as self-location decisions. By actualizing autonomous driving and C-ITS technologies, the demand for precise information on HD map have increased. And also the demand for the creation of new information based on the convergence of various changes and real-time information have increased. In this study, domestic and international HD map standards and related environments have analyzed. Based on this, usability has researched which comparison with standard HD map established by various institutions. Additionally, usability of standard HD map have studied for applying actual autonomous vehicles by reworking HD map. By the result of study, standard HD map have well established to use by various institutions. If further research about layer classification and definition by institutions will carried out based on this study, it has expected that and efficient establishment and renewal of HD map will take place.

• Journal of Elementary Mathematics Education in Korea
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• v.20 no.4
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• pp.737-760
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• 2016

This study analyzed the 2009 revised curriculum 6th grade math geometric domain and developed virtual operation tool contents based RME theory. These materials were examine to find out how to effect on the spatial sense and mathematical attitudes by applying it to teach the 6th grade students. The results were as follows. First, it is more effective for improving spatial sense to study mathematics based RME theory with virtual operation tool contents than normal one. This means that mathematics study based RME theory with virtual operation contents overcomes the limitations of flat learning environment. And it is great educational and effective method for students to improve their spatial sense. Second, it is more effective for improving mathematical attitudes to study mathematics based RME theory with virtual operation tool contents than normal one. This means that Mathematics study based RME theory with virtual operation contents makes student more participate learning actively. It helps the students who have passive learning habits to have self-directed learning habits, ability to cooperation and communicate. The results of this study suggest that mathematics study based RME theory is very helpful for student to improve their spatial sense and have positive effect on self-concept in mathematics, attitudes toward mathematics and improving study habits in mathematical attitudes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.12
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• pp.1071-1086
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• 2016

The safety of aircraft can be threatened by environmental factors, such as icing, turbulence, and lightning strike. Due to its adverse effects on aircraft structure and electronic components of aircraft, lightning strike is one of the biggest hazards on aircraft safety. Lightning strike can inject high voltage electric current to the aircraft, which may generate strong magnetic field and extreme hot spots, leading to severe damage of structure or other equipment in aircraft. In this work, mechanism of lightning strike and associated direct and indirect effects of lightning on aircraft were studied. First, on the basis of aircraft lightning regulations provided by Aerospace Recommended Practice (ARP), we considered different lightning waveform and zones of an aircraft. A coupled thermal-electrical computational model of ABAQUS was then used for simulating flow of heat and electric current caused by a lightning strike. A study on fuel tank, with and without lightning protection system, was also conducted using the computational model. Finally, electric current flow on two full scale airframes was analyzed using the EMA3D code.

• Journal of Digital Convergence
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• v.15 no.11
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• pp.591-601
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• 2017

The purpose of this study was to investigate the relationship between psychomotorik and brain function in domestic and foreign literature, and to clarify the mechanism of psychomotorik from the viewpoint of brain science, and to provide the teachers, therapists, The purpose of this study is to provide basic data which can enhance the understanding of the mechanism of psychomotorik. From the viewpoint of brain science, the study of domestic and foreign literature related to the mechanism of psychomotorik and the positive learning environment and various physical experiences in early life through the movement of psychomotorik are very important from the brain physiological point of view. The results of this study showed that the more the children move, the more the learning is improved and the healthy emotional control ability is improved and the brain is more likely to be optimized. Therefore, it is considered that this study, which has been studied through the brain science approach, provided very important basic information to understand the relation between movement of psychomotorik and brain function. In particular, understanding the possibility of optimizing the brain by cultivating a healthy emotional control ability and improving learning as children move more and more is considered to be a necessary process for educating our children well in the future. Until now, research on psychomotorik and brain function was lacking. Through this study, I hope that more people will have an opportunity to expand their understanding of the psychomotorik.