• Journal of Korean Elementary Science Education
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• v.29 no.4
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• pp.552-566
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• 2010

This paper is an in-depth case study to analyze integrated elementary science lesson planning and practical teaching by two teachers at an urban elementary schools. One is an experienced teacher and the other is a beginning teacher. For this study, researchers asked teachers to design 5 stages of lesson planning after sharing basic theories about the integrated science education. The first of the 5 lesson planning stages is curriculum analysis and choice of integrated science topic. The second stage is constructing the frame of integrated science lesson contents, and the third is drawing a diagram of the integrated science lesson development. The fourth stage is making a table of lesson plans, and the last stage is writing integrated science lesson plans. Then, the teachers implemented the lessons they created. They taught students one unit of science which is composed of 8 lessons. Difficulties that teachers meet during designing plans and integrated science class were analyzed. 5 staged lesson planning, video transcriptions, teacher interview about lesson planning and teaching, researchers' checklists, reports of inspection classes, teachers' self evaluation, and students interviews were used for this study. One of the significant results of this study is that both experienced and beginning teachers had many difficulties in deciding on time to teach and contents of science and other subjects, as well as selection and organization of whole topics of integrated science teaching. The beginning teacher especially had greater issues with developing definite teaching-learning strategy to conduct thoughts and views for integrated science at the whole unit and each lesson. However, the experienced teacher was using various teaching-learning strategies by utilizing integrated science teaching professionalism to develop students' integrated thinking ability during the instruction of other subjects. The outcomes of this study are that both teachers could deeply understand the need and value of integrated science education at the elementary school through planning and teaching 8 lessons, and that they could have self-confidence with development of teaching professionalism for integrated science teaching. It may be possible that this study could help the development of pre- and in-service program for improvement of integrated science teaching professionalism for elementary school teacher.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2B
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• pp.117-128
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• 2006

For the legacy IEEE 802.15.3 WPAN protocol, an unpredictable piconet coordinator(PNC) leaving from a piconet without a proper handoff procedure causes an absence of PNC, and thus the piconet gets collapsed. In addition, several beacons from PNCs in adjacent piconets may be collided on a device(DEV) located between those piconets. This beacon collision eventually makes the DEV leave from the piconet. To remedy these two problems, we here propose an Active Seamless Coordinator Switching(ASCS) scheme and a PNC HB based Beacon Alignment(PHBA) one. In the ASCS scheme, a PNC assigns a number of DEVs as next possible PNCs in sequence for provisioning against the abrupt breakdown of the current active PNC. Each nominated DEV proactively sends a probe frame to confirm the operation status of the active PNC. For the case of no response from the PNC, the nominated DEV tries to become a new PNC immediately. In the second PHBA scheme, each PNC is allow to broadcast a special Heart Beat(HB) frame randomly during a superframe period. When a DEV receives a HB frame from other PNC, it promptly sends the related PNCs a special Hiccup Beat(HCB) frame with the superframe information of its associated PNC. As a result, the HCB frame makes both PNCs align their superframe beginning time in order to yield no more beacon collisions. For these two proposed schemes, we show the performance by simulations. We can confirm the enhancement of throughput for each superframe and average frame transfer delay, since each scheme can reduce the duration of piconet collapse. Finally, it is worth while to note that the proposed schemes can be operated with frames those are permitted in the legacy WPAN standard.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1115-1120
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• 2004

In this paper, a CSSMA/AI MAC protocol for data services in packet CDMA network is presented. The main features of this protocol are the code status sensing and code reservation for reducing the packet collision. The base station broadcasts the code status on a frame-by-frame basis just before the beginning of each preamble transmission, and the mobile station transmits a preamble for reserving a randomly selected code based on the received code status. After having transmitted the preamble, the mobile station listens to the downlink of the selected code and waits for the base station reply. If this reply indicates that the code has been correctly acquired, it continues the packet transmission for the rest of the frame. If there are other packets waiting for transmission, the base station broadcasts the status of the code as reserved, and the mobile station transmits a packet on a reserved code for the successive frames.

• Structural Engineering and Mechanics
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• v.86 no.6
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• pp.739-750
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• 2023

This study examines the two-level behavior of the toggle brace damper within a steel frame having a yielding pipe damper and rotational friction damper. The proposed system has two kinds of fuse for energy dissipation in two stages. In this mechanism, rotational friction damper rather than hinged connection is used in toggle brace system, connected to a pipe damper with a limited gap. In order to create a gap, bolted connection with the slotted hole is used, such that first a specific movement of the rotational friction damper solely is engaged but with an increase in movement, the yielding damper is also involved. The performance of the system is such that at the beginning of loading the rotational friction damper, as the first fuse, absorbs energy and with increasing the input load and further movement of the frame, yielding damper as the second fuse, along with rotational friction damper would dissipate the input energy. The models created by ABAQUS are subjected to cyclic and seismic loading. Considering the results obtained, the flexibility of the hybrid two-level system is more comparable to the conventional toggle brace damper. Moreover, this system sustains longer lateral displacements. The energy dissipation of these two systems is modeled in multi-story frames in SAP2000 software and their performance is analyzed using time-history analysis. According to the results, permanent relocations of the roof in the two-level system, in comparison with toggle brace damper system in 2, 5, and 8-story building frames, in average, decrease by 15, 55, and 37% respectively. This amount in a 5-story building frame under the earthquakes with one-third scale decreases by 64%.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.2
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• pp.32-43
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• 1997

Abstract A series of permeability tests was performed on the mixtures with specific mixing rates of sand and bentonite using modified rigid-wall permeameter. Sand-bentonite mixtures were permeated by organics, ethanol and TCE. Permeability of bentonite with several mixing rates had a tendency to decrease up to initial one pore volume and permeability was thereafter converged to a constant value. When sand-bentonite mixtures was permeated by water, permeability was decreased at the beginning but it was thereafter converged to a constant. Among several mixing rates, permeability was greatly decreased at 15% of mixing rate. When sand-bentonite mixtures with 15% mixing rate was permeated by ethanol, permeability was about 10 times larger value than permeability of water. Peameability was shown greater values when permeated by TCE (TrichloroEthylene) followed by ethanol. Suitable mixing rate of sand-bentonite for a liner of waste landfills was detected.

• Journal of the Korean Society of Systems Engineering
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• v.5 no.1
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• pp.43-48
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• 2009

Korean Tilting trains have been tested on conventional lines since the beginning of 2007 for evaluating its reliability. We achieved some major performance tests which are the maximum operation speed, 180km/h test and the maximum curves increasing speed, over 30 percentage comparing with non-tilling operation train. In order to analysis reliability data of tilting train, we have used the special system engineering frame with interfacing between component suppliers effectively. And also we have developed the data aquisition system which consists of monitor, sensors and depot computer etc. As a results of calculation, until now we realized that the reliability are getting more increasing than starting point of running field test.

• International Journal of High-Rise Buildings
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• v.5 no.4
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• pp.305-318
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• 2016

In the design of super-tall towers, engineers often find the conventional frame systems used in countless buildings in the past decades incapable of providing the required form, performance and constructability demanded by super-tall heights. The strength of the diagrid as a structural system in high-rise towers is the total flexibility it affords the designer as an adaptable, efficient and buildable scheme. Using fundamental engineering principles combined with modern computational tools, designers can take minimum load path forms to create rationalized diagrid geometries to create optimized, highly efficient towers. The use of diagrid frames at SOM has evolved as a structural typology beginning with the large braced frames on the John Hancock Center and continued in modern applications proving to be a powerful system in meeting the demands of supertall buildings.

• Journal of architectural history
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• v.2 no.2 s.4
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• pp.107-118
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• 1993

For attempting to wright a history of Modern Architecture in Korea the first task might be to establish the beginning of the period and to search for the orign of Modernity in Korean Architecture. As a member of the third world Modernism and Modernity in Korean Modern architecture has to be different from that of the West. The main purpose of this study is to define Modernity and to find out the characteristics of Modernism in Korean architecture. Above all this study suggests to note the peculiarity and the differance in the history of Modern architecture within the large frame of modernization. Then maintains that the search for the new cultural identity and rationality instead of lost tradition and convention can be defined as a modernity in Korean architecture.

• Journal of Ubiquitous Convergence Technology
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• v.1 no.1
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• pp.42-46
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• 2007

In this paper, we proposed an efficient short address allocation mechanism for WiBEEM devices using NAA(Next Address Available) algorithm. The proposed addressing mechanism is based upon the NAA information that is delivered over the beacons every time it is transmitted at the beginning of each super-frame. The NAA-based addressing mechanism is not a systematic way of allocating short addresses to newly joining devices and thus tree-routing cannot be supported. However, it has great advantages when U-City core services including U-Parking Lot System or ATIS(Advanced Traveler Information System) services that require high-speed mobility are considered. Moreover, the proposed addressing mechanism can provide significant expandability of the wireless network to various applications and fast device discovery.

• Journal of the Korean Institute of Landscape Architecture
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• v.20 no.3
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• pp.44-44
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• 1992

The existing urban open space system of the German cities has an exellent frame, which is a result of the long history of its developing. The beginning time of that goes back to the end of the 18th century, as pri-vate gardens of feudal lords and the nobility became more and more public and public open space plannedwas appearing. Through the change from the feudal age to the civil society, the people's values on the urbanopenspace were growing. so that it had more social meanings. Since the Industrial Revolution in the secondhalf of the 19th century the environment of cities was getting miserable, what was the important cause ofthe birth of ideas and concepts of the urban open space type and its system.The fo1lowing concepts are they. which have influenced modern open space concepts of the cities InGermany decisively :'Garden Cities'.'Neighborhood'. 'The Model of Mohring, Eberstadt and Petersen','The Model of Langen'. "The Classified City','The Classified and Loosened City'etc.