• Fisheries and Aquatic Sciences
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• v.5 no.2
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• pp.114-121
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• 2002

A correction index of catchability (CIC) was derived using a 6 year research data set to examine the seasonal variation in catchability for the night time prawn fishery in Albatross Bay. CIC reflects the composite effect of the monthly variation in size selectivity, emergence­burying behaviour and population density variation of prawn populations. The values of CIC for four dominant species, Metapenaeus endeavouri, M. ensis, Penaeus semisulcatus and P. esculentus, were examined. The value of CIC for M. endeavouri varied substantially and was the highest in August. The values of CIC for M. ensis were high during November to March and the seasonality was weaker than that for M. endeavouri. The monthly variation in CIC for P. semisulcatus reflected the seasonal variation in population density, being high during November to February. These results suggest that the catch ability of P. esculentus is steady throughout the year but it varies greatly on a seasonal basis for M. endeavouri.

• Health Policy and Management
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• v.14 no.2
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• pp.138-162
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• 2004

This study was performed to investigate small area variation in rates of three common surgeries in general surgery department across 156 small areas. Three surgery rates were analyzed; Anal and/or stomal procedures, inguinal and/or femoral hernia procedures, appendectomy. Methods: We used health insurance claims data and the number of patients were 13,845, 2,154 and 7,151 persons respectively. Surgery rates were directly standardized with age and sex and logistic regression was used to analyze surgery rates. Results: Mapping of the surgery rates, there was small area variation in anal and/or stomal procedures. The clinic which was located in more competitive market and chose DRG payment system tends to do more anal and/or stomal procedures. There was no factor except DRG bed rates had effect on rate of inguinal and/or femoral hernia procedures. Conclusions: Findings of this study will contribute to developing investigation method on small area variation and policy to reduce the variation such as developing evidence based medical practice guideline.

• International Journal of Quality Innovation
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• v.4 no.1
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• pp.148-159
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• 2003

Variation is the archenemy of quality. To reduce or control the variation in a complex production unit, firstly we need to identify the location of the root cause of the variation. This paper discusses the detection of variability and the techniques used for reduction of variation for a production unit consisting of many processes. In the first part of this paper, the background of variability detection in production systems is introduced which is then followed by a weighted network corresponding to correlation matrix of all processes. Based on the network and clustering criterion of maximum spanning tree, a classification of all processes is derived. Furthermore, the variation of each process in a class is determined by residual analysis. In the last part, the use of methods of robust design for the processes with a larger variability is discussed.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1993.10a
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• pp.185-190
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• 1993

In this paper, we investigate the effect of production uncertainty - especially demand fluctuation and activity time variation, to production control policies. First, we examine three famous production control policies, namely, MRP, JIT, OPT, from shop floor control perspective and analyze the difference among them. Based on these, simulation studies are performed to draw out the effects of demand fluctuation which are classified into demand lumpiness and demand irregularity, and, the effects of activity time variation which are classified into standard time variation and non-standard time variation. Experimental investigation shows that, in terms of demand fluctuations, MRP is affected by demand lumpiness, but JIT by demand irregularity. And we also see that both MRP and JIT are influenced by standard time variation with respect to activity time variations.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1460-1466
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• 2011

This paper proposes the algorithm for discriminating faults from the variation due to the operation of non-linear components to prevent the mal-operation of protection relay in the distribution system. An IEEE 13 node test feeder is modeled to analyze the characteristics of the fault and each variation using EMTP-RV. Simulations with various operating conditions of transformers, non-linear loads, and unbalanced loads are performed using the test feeder model. Based on simulation results, the wavelet transform is adopted to analyze the current waveforms from the faults and variations to find out the differences between them and the algorithm for discriminating faults from the variation is proposed. The proposed algorithm is verified by using the current waveforms simulated in the KEPCO's distiribution system and IEEE 13 node test feeder.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.12
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• pp.2157-2165
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• 2006

In implementing GCRA, well known as the representative user traffic policing algorithm for constant-bit rate service, it is essential to set proper values for delay variation tolerance in order to prevent network overload and excessive user data loss due to delay variation incurred inevitably during transmission process. In this paper, we investigate the performance of GCRA algorithm for various values of delay variation tolerance and suggest a guideline for setting proper delay variation tolerance values.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1213-1218
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• 2007

The brake judder comes from non-uniformities in the tire/wheel assembly caused by mechanical effects such as a brake torque variation (BTV). A disc thickness variation (DTV) related with the kinematic behavior of the disc was investigated a main source of BTV. In this study, a dynamic model with brake corner assembly of full vehicle using MSC.ADAMS was correlated by experiment of judder phenomenon. Judder was generated and correlated systematically by judder experiment in chassis and brake dynamometer from variation in the thickness of the disc. Also it has been found a judder transfer path and variation of the braking pressure. Through analysis of transfer function and movement of subsystem caused by BTV generation, design parameters have been found. Based on the results obtained from parameter study of suspension module, the effective design process and developed model with brake corner assembly was suggested for vibration reduction of steering wheel caused by the judder phenomenon.

• Korean Institute of Interior Design Journal
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• v.14 no.1
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• pp.64-72
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• 2005

The purpose of this study was to analyze the flexible system in a typological way that develops and promotes the various methods of flexible system. The main method of this study was literature review and content analysis on various flexible systems and a case study of flexible housing. The flexible system in this typological analysis was classified into two categories: 'Elements of Flexibility' and 'Variation'. The category of Flexibility Elements was categorized into 'Primary Elements'(e.g., walls, floors, and ceilings),'Secondary Elements'(e.g., doors, windows, and furniture), and 'Tertiary Elements'(e.g., lighting, hues and finishing materials). Variation Effect was classified into 'Visual Variation', 'AppBicative Variation', and 'Layout Variation'. Also, Variation could be classified into 'Finish-centered', 'Application-centered', and 'Layout-centered' The flexible system developed in this study is a basis for further concrete flexible methods.

• Bulletin of the Korean Mathematical Society
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• v.45 no.1
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• pp.75-93
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• 2008

The rate of convergence of the distribution of order statistics to the corresponding extreme-value distribution may be characterized by the uniform and total variation metrics. de Haan and Resnick [4] derived the convergence rate when the second order generalized regularly varying function has second order derivatives. In this paper, based on the properties of the generalized regular variation and the second order generalized variation and characterized by uniform and total variation metrics, the convergence rates of the distribution of the largest order statistic are obtained under weaker conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.11
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• pp.2401-2408
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• 1997

The measured pulse shapes provided in the given data package demonstrated pulse distortions due to laser speckle. the distorted pulse shapes were carefully analyzed, modeled, and then applied to the DTTL(Digital-data Transition Tracking Loop)[1] bit synchronizer simulator to measure the mean time delay and its delay variation performance. The result showed that the maximum mean time delay variation with the modeled data was 12.5% when window size equals 1. All the data given were located within this modeled boundary and the maximum eman time delay variation was 7% in this case. The mean time delay variation was known to be smaller by reducing the window size [2][5][6]. The mitigated delay variation was 2.5% in the modeled case and 1.4% in the data set given when the windown size equals 0.1. With the digital DTTL insteal of analog DTTL, similar results was obtained.