• 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 Music and Human Behavior
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• v.11 no.1
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• pp.1-19
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• 2014

The purpose of this study was to investigate the immediate effect of Patterned Sensory Enhancement (PSE) technique on the motor function of the affected upper limb in hemiplegic stroke patients by comparing the use of PSE and simple rhythmic cue. A total of 16 stroke patients were recruited from rehabilitative hospitals. The participants were assigned to the experimental group (n = 8) and control group (n = 8). While performing six different upper limb motions, musical stimuli applying the PSE technique was presented for the experimental group and simple rhythmic cue using the metronome was applied for the control group. The results showed that while the significantly increased range of motion (ROM) was found in the experimental group with the immediate use of PSE (p < .05), the control group did not show no significant change. This study implies that the use of musical elements in cueing for upper limb motion immediately leads to significant improvement in ROM by providing sufficient temporal, spatial, and dynamic information for expected motor performance.

• Journal of the Korean association of regional geographers
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• v.7 no.3
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• pp.107-120
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• 2001

This study is concerned with providing a reliable procedure of calibrating a set of places specific distance parameters and with applying it to U.S. inter-State migration flows between 1985 and 1900. It attempts to conform to recent advances in quantitative geography that are characterized by an integration of ESDA(exploratory spatial data analysis) and local statistics. ESDA aims to detect the spatial clustering and heterogeneity by visualizing and exploring spatial patterns. A local statistic is defined as a statistically processed value given to each location as opposed to a global statistic that only captures an average trend across a whole study region. Whereas a global distance parameter estimates an averaged level of the friction of distance, place-specific distance parameters calibrate spatially varying effects of distance. It is presented that a poisson regression with an adequately specified design matrix yields a set of either origin-or destination-specific distance parameters. A case study demonstrates that the proposed model is a reliable device of measuring a spatial dimension of migration, and that place-specific distance parameters are spatially heterogeneous as well as spatially clustered.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.103-113
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• 2020

Jack-up drilling rigs are widely used in the offshore oil and gas exploration industry. Although originally designed for use in shallow waters, trends in the energy industry have led to a growing demand for their use in deep sea and harsh environmental conditions. To extend the operating range of jack-up units, their design must be based on reliable analysis while eliminating excessive conservatism. In current industrial practice, jack-up drilling rigs are designed using the working(or allowable) stress design (WSD) method. Recently, classifications have been developed for specific regulations based on the load and resistance factor design (LRFD) method, which emphasises the reliability of the methods. This statistical method utilises the concept of limit state design and uses factored loads and resistance factors to account for uncertainly in the loads and computed strength of the leg components in a jack-up drilling rig. The key differences between the LRFD method and the WSD method must be identified to enable appropriate use of the LRFD method for designing jack-up rigs. Therefore, the aim of this study is to compare and quantitatively investigate the differences between actual jack-up lattice leg structures, which are designed by the WSD and LRFD methods, and subject to different environmental load-to-dead-load ratios, thereby delineating the load-to-capacity ratios of rigs designed using theses methods under these different enviromental conditions. The comparative results are significantly advantageous in the leg design of jack-up rigs, and determine that the jack-up rigs designed using the WSD and LRFD methods with UC values differ by approximately 31 % with respect to the API-RP code basis. It can be observed that the LRFD design method is more advantageous to structure optimization compared to the WSD method.