• The Mathematical Education
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• v.41 no.3
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• pp.341-360
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• 2002

The purpose of the study was to investigate the effectiveness of dynamic software in solving high school analytic geometry problems compared with traditional algebraic approach. Three high school students who have revealed high performance in mathematics were involved in this study. It was considered that they mastered the basic concepts of equations of plane figure and curves of secondary degree. The research questions for the study were the followings: 1) In what degree students understand relationship between geometric approach and algebraic approach in solving geometry problems? 2) What are the difficulties students encounter in the process of using the dynamic software? 3) In what degree the constructions of geometric figures help students to understand the mathematical concepts? 4) What are the effects of dynamic software in constructing analytic geometry concepts? 5) In what degree students have developed the images of algebraic concepts? According to the results of the study, it was revealed that mathematical connections between geometric approach and algebraic approach was complementary. And the students revealed more rely on the algebraic expression over geometric figures in the process of solving geometry problems. The conceptual images of algebraic expression were not developed fully, and they blamed it upon the current college entrance examination system.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.3 no.3
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• pp.149-153
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• 2022

The degree distribution of the plant-pollinator network was identified by analyzing the data in the ecosystem and reproduced by a model of the growing bipartite mutualistic networks. The degree distribution of pollinator shows power law or stretched exponential distribution, while plant usually shows stretched exponential distribution. In the growth model, the plant and the pollinator are selected with probability P_p and P_A=1-P_p, respectively. The number of incoming links for the plant and the pollinator is l_p and l_A, respectively. The probability that the link of the plant selects the pollinator of the existing network given as $A_{k_i}=k^{{\lambda}_A}_i/{\sum}_i\;k^{{\lambda}_A}_i$, and the probability that the pollinator selects the plant is $P_{k_i}=k^{{\lambda}_p}_i/{\sum}_i\;k^{{\lambda}_p}_i$. When the nonlinear growth index is 𝛌_X=1 (X=A or P), the degree distribution follows a power law, and if 0≤𝛌_X<1, the degree distribution follows a stretched exponential distribution. The cumulative degree distributions of plants and pollinators of 14 empirical plant-pollinators included in Interaction Web Database were calculated. A set of parameters (P_A,P_P,l_A,l_P) that reproduces these cumulative degree distributions and a growth index 𝛌_X (X=A or P) were obtained. We found that animal takes very heterogenous connections, whereas plant takes a more flexible connection network.

• The Transactions of the Korea Information Processing Society
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• v.5 no.5
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• pp.1311-1319
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• 1998

The methods of providing available bandwidth adaptively using feedback to maximize the utilization of network as well as the quality of service have been the focus of recent research activities for ATM(Asynchronous Transfer Mode). This study has been extended from the point-to-point connection to a point-to-multipoint environment as the number of applications requiring multicast service increases. It is known that the effectiveness of feedback based congestion control scheme diminishes as propagation delay increases. Especially for a multicast connection consisting of various paths and destinations with different performance and congestion status, the problem of unfairness due to different propagation delays may occur. The degree of such unfairness may change depending on various aspects of congestion control schemes. These has been, however, relatively little study on these problems. In this paper, we present how various aspects of control schemes-length of the interval between feedback generations, point of time to coalesce feedback cells from child paths, decreasing factor of source rate in case of congestion-affect the degree of unfairness. Simulation results show that degree of unfairness changes according to when the feedback coalescing happens. Expecially it is shown that the effect of feedback coalescing time to the degree of unfairness is more significant for the smaller feedback interval. It is also found that as the source rate decreasing factor becomes larger the average ACR(Allowed Cell Rate) at the source gets lower and the degree of unfairness grow larger.

• Journal of Korean Society of Steel Construction
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• v.16 no.2 s.69
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• pp.235-245
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• 2004

The advantages of composite construction are now well understood in terms of structural economy, good performance in service, and ease of construction. However, these conventional composite construction systems have some problems in application to steel framed buildings due to their large depth. So, in this study we executed an experimental test with the "Slim Floor"system which could reduce the overall depth of composite beam. Slim Floor system is a method of steel frame multi-story building construction in which the structural depth of each floor is minimized by incorporating the steel floor beams within the depth of the concrete floor slab. Presented herein is an experimental study that focuses on the flexural behaviour of the partially connected slim floor system with asymmetric steel beams encased in composite concrete slabs. Eight full-scale specimens were constructed and tested in this study with different steel beam height, slab width, with or without shear connection and concrete topping thickness. Observations from experiments indicated that the degree of shear connection without additional shear connection was $0.53{\sim}0.95$ times that of the full shear connection due to inherent mechnical and chemical bond stress.

• Journal of Korean Society of Steel Construction
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• v.16 no.4 s.71
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• pp.425-432
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• 2004

Large studs were suggested not only for the design of steel-concrete composite bridges with simplified sections but also for the shear connection in precast decks requiring uniform distribution of shear pockets. Based on the push-out test results on studs with diameters of more than 25 mm, partial composite beams with 40%-degree shear connection were fabricated, and static tests were performed. The ultimate strength and horizontal shear load redistribution of partial composite beams, which have parameters of stud shank diameters and distribution, were evaluated, and group failure in the shear span was observed. Since the flexural strength of composite beams are dependent on the strength of their shear connection, the strength of the stud connection was estimated and it showed considerably higher shear strength. From the load-slip curves, the sufficient ductility and load redistribution of large studs were confirmed. Uniformly distributed large studs can provide proper ultimate behavior of composite beams.

• Steel and Composite Structures
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• v.34 no.5
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• pp.625-641
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• 2020

The realistic modeling of the beam-column semi-rigid connection in steel frames attracted the attention of many researchers in the past for the seismic analysis of semi-rigid frames. Comparatively less studies have been made to investigate the behavior of steel frames with semi-rigid connections under different types of earthquake. Herein, the seismic behavior of semi-rigid steel frames is investigated under both far and near-field earthquakes. The semi-rigid connection is modeled by the multilinear plastic link element consisting of rotational springs. The kinematic hysteresis model is used to define the dynamic behavior of the rotational spring, describing the nonlinearity of the semi-rigid connection as defined in SAP2000. The nonlinear time history analysis (NTHA) is performed to obtain response time histories of the frame under scaled earthquakes at three PGA levels denoting the low, medium and high-level earthquakes. The other important parameters varied are the stiffness and strength parameters of the connections, defining the degree of semi-rigidity. For studying the behavior of the semi-rigid frame, a large number of seismic demand parameters are considered. The benchmark for comparison is taken as those of the corresponding rigid frame. Two different frames, namely, a five-story frame and a ten-story frame are considered as the numerical examples. It is shown that semi-rigid frames prove to be effective and beneficial in resisting the seismic forces for near-field earthquakes (PGA ≈ 0.2g), especially in reducing the base shear to a considerable extent for the moderate level of earthquake. Further, the semi-rigid frame with a relatively weaker beam and less connection stiffness may withstand a moderately strong earthquake without having much damage in the beams.

• Journal of Korean Elementary Science Education
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• v.33 no.2
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• pp.335-351
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• 2014

The 96 elementary school teachers' the degrees of understandings about the characteristics of the currents according to the connection methods of batteries in simple electric circuits were investigated. In this study, the concepts on the characteristics of currents according to the connection methods of batteries were divided 'the learned concepts' and 'the differentiated concepts'. The characteristics of the currents in the region of the larger resistance of load than the internal resistance of a battery were called the learned concepts, they are taught in the science curriculum. While the characteristics of the currents in the region of the smaller resistance of load than the internal resistance of a battery were called the differentiated concepts, they are not exposed clearly in the science curriculum. The results obtained in this study are as follows: The average score related to the learned concepts was relatively high, while the degree of the teachers' cognitions of the internal resistance of a battery and the resistance of wires were low. Also the average score related to the differentiated concepts was very low because it seems so new to the elementary school teachers. It strongly suggests that the elementary school teachers did not understand meaningfully the characteristics of the currents related to the connections of batteries on the ground of the cognitions of the internal resistances of batteries and the resistances of loads in simple electric circuits. Hence, they might experience difficulties due to the problems occurred in relation to the connections of batteries in the elementary school science lessons.

• Journal of the Korean GEO-environmental Society
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• v.8 no.1
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• pp.49-55
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• 2007

In order to utilize treads of waste tire as reinforcement material it is necessary to know the interface friction angle between tread surfaces and soil and tensile strength of connection joint of tire treads. In this research large direct shear tests were performed to get the interface friction angle between the inner and outer surfaces of treads and soil for different degree of compaction. From the large direct shear tests, the ratio of interface friction angle to the shear friction angle of sand, ${\delta}/{\phi}$, were 1.06 in outside surface of tire tread and 0.93 in inside surface of tire tread. For weathered granite soil the ratio of interface friction angle was 0.98 and 0.92 for outside and inside of tread, respectively. Also tensile tests were performed using universal testing machine for the connection joint of treads and Tirecell units using bolts. The tensile strength of connection joint increased with the number of bolts and with the sizes of washers. Connection by polypropylene ropes showed lower strength than those of bolts.

• Journal of Distribution Research
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• v.4 no.1
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• pp.31-49
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• 1999

The present paper discusses the current status of outsourcing of service encounter in department stores. We attempt to find if there is any significant relationship between outsourcing motive and business performance. The 30 department stores under analysis show that they vary in the degree to which they appreciate the necessity of outsourcing and also the which they employ outsourcing. It is also found that firm size influences the portion of outsourcing. The two main motives of outsourcing seem to be (i) cost saving and (ⅱ) better customer satisfaction. We find that the latter plays a more important role. However, there seems to be no significant connection between outsourcing and performance and between motives of outsourcing and performance.

• Journal of Korean Port Research
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• v.12 no.1
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• pp.47-53
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• 1998

Presently, it was faced with serious social problems as traffic accident, parking violation & traffic congestion due to change of industrial structure, expansion of economic volume, elevation of national life level and rapid motorization. Accordingly, the study is research to improve immidiate transportation problems which could be establish the rating model about consideration degree of evaluation factor based on MDPREF's method in connection with Intelligent Transportation System(ITS)