• 한국초등과학교육학회지:초등과학교육
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• 제27권1호
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• pp.83-92
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• 2008

In this study, we developed elementary science education modules for facilitating students' understanding of the connected nature of Science-Technology-Society. For these modules, we particularly used news articles to make connections among science, technology, and society. We set up the development criteria as followings: connecting science-technology-society, aligning with national science curriculum, respecting students' interest, and appropriating the difficulty levels in terms and concepts. We also studied 4th grade students' perception of using these modules in science lessons. Most students perceived that using the modules in their science classes helped them link science-technology-society intimately and enhance their interest and motivation, as well as their self-esteem for studying science.

• International Journal of Automotive Technology
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• 제6권1호
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• pp.71-77
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• 2005

This paper presents a systematic approach which determines the optimal period to minimize performance measure subject to the schedulability constraints of a real-time control system by formulating the scheduling problem as an optimal problem. The performance measure is derived from the summation of end-to-end response times of processed I/Os scheduled by the static cyclic method. The schedulability constraint is specified in terms of allowable resource utilization. At first, a uniprocessor case is considered and then it is extended to a distributed system connected through a communication link, local-inter network, UN. This approach is applied to the design of an automotive body control system in order to validate the feasibility through a real example. By using the approach, a set of optimal periods can easily be obtained without complex and advanced methods such as branch and bound (B&B) or simulated annealing.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권1호
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• pp.26-51
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• 2009

In this paper, we propose an empirical framework for modeling and emulating interference in multi-hop wireless ad-hoc networks. Wireless interference causes wide variation in the frame delivery rate at a link, and thus we cannot represent the state of the link with only two states, connected state and disconnected state, as in wired networks. We first investigate wireless interference in detail, in order to accurately calibrate the interference and identify its underlying attributes, and then we simulate the diverse occurrences and effects of interference, after incorporating the scheme into a simulation tool. Based on these observations, we devise a modeling and simulation framework with several control parameters, and perform an extensive set of simulation studies. The simulation results indicate that the proposed framework enables us to examine various attributes of wireless interferences and their effects on wireless network protocols and systems.

• Structural Engineering and Mechanics
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• 제11권2호
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• pp.133-149
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• 2001

A high-fidelity model of a tracked vehicle traversing a flexible ground terrain with a varying profile is presented here. In this work, we employed a recursive formulation to model the track subsystem. This method yields a minimal set of coordinates and hence, computationally more efficient than conventional approaches. Also, in the vehicle subsystem, the undercarriage frame is assumed to be connected to the chassis by a revolute joint and a spring-damper unit. This increase in system mobility makes the model more realistic. To capture the vehicle-ground interaction, a Winkler-type foundation with springs-dampers is used. Simulation runs of the integrated tracked vehicle system for vibrations for four varying ground profiles are provided.

• 한국컴퓨터정보학회논문지
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• 제21권5호
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• pp.73-77
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• 2016

This paper deals with the network reliability problem that decides the communication line between main two districts while the k districts were destroyed in military communication network that the n communication lines are connected in m districts. For this problem, there is only in used the mathematical approach as linear programming (LP) software package and has been unknown the polynomial time algorithm. In this paper we suggest the heuristic algorithm with O(n) linear time complexity to solve the optimal solution for this problem. This paper suggests the flow path algorithm (FPA) and level path algorithm (LPA). The FPA is to search the maximum number of distinct paths between two districts. The LPA is to construct the levels and delete the unnecessary nodes and edges. The proposed algorithm can be get the same optimal solution as LP for experimental data.

• 전기학회논문지
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• 제63권4호
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• pp.445-450
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• 2014

Jeju power system is connected to the mainland power system through HVDC, and receives about half of required electricity through the HVDC lines. Jeju power system already experienced black out when a generator tripped at the moment of the HVDC line faults. But, UFR operated as was expected when HVDC line fault occurred at that time. As the penetration level of wind turbines increases, it is required to set UFR again considering intermittent wind turbin outputs. In this paper, we address a new way of UFR setting through computer simulation.

• Progress in Superconductivity
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• 제14권2호
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• pp.87-91
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• 2012

Metallic magnetic calorimeters (MMCs) are one of the most competitive low temperature detector (LTD) readout sensors. They have the advantages of high time resolution, no heat dissipation, and a wide range of operating temperature. We apply MMCs to our neutrinoless double beta decay ($0v{\beta}{\beta}$) search experiment. A $CaMoO_4$ crystal was employed as both a source of $0v{\beta}{\beta}$ and an energy absorber. The crystal was thermally connected to a MMC sensor. We set a simple thermal model for this detector and measured pulse shapes are compared with a numerical solution of the thermal model.

• 제어로봇시스템학회논문지
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• 제10권7호
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• pp.590-596
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• 2004

A passivity-based dynamic output feedback controller design is considered for a finite collection of non-square linear systems. Design of a single controller for a set of plants i.e. simultaneous stabilization is an important issue in the area of robust control design. We first determine a squaring gain matrix and an additional dynamics that is connected to the systems in a feedforward way, then a static passivating control law is designed. Consequently, the actual feedback controller will be the static control law combined with the feedforward dynamics. A necessary and sufficient condition for the existence of the parallel feedforward compensator is given by the static output feedback formulation. In contrast to the previous result [1], a technical condition for constructing the parallel feedforward compensator is removed by proposing a new type of the parallel compensator.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.867-871
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• 2004

In this paper, a new analytic approach for shape preserving contrast enhancement is presented. Contrast enhancement is achieved by means of segmental histogram stretching modification which preserves the given image shape, not distorting the original shape. After global stretching, the image is partitioned into several level-sets according to threshold condition. The image information of each level-set is represented as typical value based on grouped differential values. The basic property is modified into common local schemes, thereby introducing the enhanced effect through extreme discrimination between subsets. The scheme is based on stretching the histogram of subsets in which the intensity gray levels between connected pixels are approximately same In spite of histogram widening, stretched by local image information, it neither creates nor destroys the original image, thereby preserving image shape and enhancing the contrast. By designing local histogram stretching operations, we can preserve the original shape of level-sets of the image, and also enhance the global intensity. Thus it can hold the main properties of both global and local image schemes, which leads to versatile applications in the field of digital epigraphy.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.311-314
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• 2000

Multicasting is the delivery of a packet simultaneously to one or more destinations using a single, local transmit operation. Typically the set of destinations is referred to as a multicast group. sources transmit to these group addresses without knowing the group's actual membership. We have studied an implementation of one model of supporting IP multicast over ATM, the Multicast over ATM model developed by the IETF(Internet Engineering Task Force). MCOA(Multicast over ATM) that includes both these modes of operation and the behavior of each in a testbed where the ATM host were connected in a WAN and LAN. WAN topology was to gain insight into the effects of larger propagation delays on the MC over ATM model.