• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.211-214
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• 2003

This paper presents the microscopic observation results from the picture frame test using five-harness satin weave fabric composite. Aligned and misaligned specimens are observed to verify the exact tow deformation pattern such as tow interval and change in tow amplitude. To observe the micro-deformation of the fabric structure, appropriate specimens from picture frame test are sectioned and observed under the microscope. From the observation results, it is found that a picture frame test with a misaligned fibre orientation angle shows large differences in deformation between tensile and compressive tow directions.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.154-157
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• 2005

This paper aims to investigate the tow deformation pattern with respect to shear angle and mold property during draping of plain weave carbon/epoxy prepreg. Aluminum and PVC foams with different foam density are used for the draping hemisphere molds with 250 mm diameters. Microscopic observation reveals that tow parameters like crimp angle and Y-directional tow intervals are influenced by shear angle and mold density at the same time. The correlation between crimp angle and Y-directional tow interval is also found out.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.99-102
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• 2003

This paper aims to observe the micro-mechanical behaviour of tow geometry during deformation of dry woven carbon-fiber fabric. With the increment of shear angle fabric experiences 'lock-up'phenomenon. In this paper, deformation of micro-mechanical parameters such as tow interval, change in tow amplitude and wavelength are investigated. To observe the micro-deformation of the fabric structure, appropriate specimens from bias extension and biaxial tests are sectioned and observed under the microscope. It was found that different loading conditions cause geometric deferences in the tow architecture.

• Composites Research
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• v.17 no.1
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• pp.38-46
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• 2004

This paper aims to correlate the micro-mechanical behaviour of tow geometry with applied in-plane forces during deformation of dry woven carbon-fibre fabric. These in-plane forces lead to differences in tow reorganisation during deformation and so changes in the way in which 'lock-up' occurs. In this paper, deformation of micro-mechanical parameters such as tow interval, crimp angle, change in tow amplitude and wavelength are investigated. To observe the micro-deformation of the fabric structure, appropriate specimens from bias extension and biaxial tests are sectioned and observed under the microscope. It was found that different loading conditions cause geometric deferences in the tow architecture. The variation in deformed tow geometry with shear angle is fitted using a simple parametric model.

• Composites Research
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• v.18 no.2
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• pp.13-19
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• 2005

In this paper deformation of micro-mechanical parameters such as tow interval, tow thickness and change in tow amplitude are investigated by using dry fabrics (Five-harness satin weave) under shear deformation. To evaluate the observation results according to the generated in-plane forces in the material, bias extension, biaxial test results are compared with. It was found that a picture frame test with a misaligned fibre orientation angle shows large differences in deformation between tensile and compressive tow directions.

• Composites Research
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• v.16 no.4
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• pp.29-35
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• 2003

In this paper. various tow parameters such as equivalent tow thickness, amplitude of longitudinal tow and tow intervals were investigated and compared with each other by using microscopic observation to find out the exact deformation patterns between both directions of the fabric structure(Longitudinal and Transverse Directions). And those observation results were compared with bias extension. biaxial tests results with dry fabric which has the same tow structure as the draped helmet materials and also compared with prepreg specimen which is cured by autoclave moulding without vacuum and pressure condition. Specimens for the observation were taken from draped helmet which is made of fabric composite(Five Harness Satin Weave). From the observation results, it was found that there are different deformation pattern between tow directions and effect of geometric condition on the deformation of the fabric materials during draping process was verified.

• Communications for Statistical Applications and Methods
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• v.7 no.3
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• pp.859-869
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• 2000

In this paper, various methods for finding confidence intervals for p of binomial parameter are reviewed. Also we introduce tow bootstrap confidence intervals for p. We compare the performance of bootstrap methods with other methods in terms of average coverage probability by Monte Carlo simulation. Advantages of these bootstrap methods are discussed.

• The Korean Journal of Applied Statistics
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• v.19 no.2
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• pp.217-230
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• 2006

e discuss proper confidence intervals for interval estimation of a low binomial proportion. A large sample surveys are practically executed to find rates of rare diseases, specified industrial disaster, and parasitic infection. Under the conditions of 0 < p ${\leq}$ 0.1 and large n, we compared 6 confidence intervals with mean coverage probability, root mean square error and mean expected widths to search a good one for interval estimation of population proportion p. As a result of comparisons, Mid-p confidence interval is best and AC, score and Jeffreys confidence intervals are next.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.299-308
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• 2001

We examined the growth variation with water depth, interval between suspended lines and locality of seedling production of sea squirt. Halocpthia roretzi, measuring approximately $10.1\~15.3$ mm in tunic height, was cultured at the farm near Guryongpo, Pohang city from 7 January to 6 December 1998 (333 days). Growth condition depending on culture depth was most favourable at the depth of $10\~12$m, It was concluded that nutritional conditions were better at the depth since there was a greater mount of phytoplankton than at any other depth in the water column. Growth condition depending on distance between suspended lines was most favourable at the interval of 2 m and 2.5 m than at the interval of t m and 1.5 m, There was no significance difference in growth variation with locality of seedling. The seasonal variations in growth of tunic height, meat and total weight were correlated with temperature and chlorophyll a, In the depth of $10\~12m$ the rate of increase in tunic height was generally greatest in the growth period II ($244{\mu}m/day$) and IV ($338{\mu}m/day$), lower in the period I ($108{\mu}m/day$), and slightly increased during the period III ($185{\mu}m/day$). The water column have showed a typical seasonal pattern with temperature ranged between $12.07{\sim}24.14^{\circ}C$ and over $20^{\circ}C$ between July and September.

• The Journal of Fisheries Business Administration
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• v.45 no.1
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• pp.63-77
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• 2014

This study is to estimate the recent changes in total factor productivity of 15 Korean adjacent water fisheries based on Malmquist productivity indices. The study adopted both input and output oriented productivity measures utilizing a hyperbola distance function. In addition to this point, the study also calculated the 95% confidence interval for the various components of the productivities in order to access the statistical significance of estimates using 2000 times of re-sampling process through the smoothed bootstraping. The results of the study showed us that there was 18% reduction in the overall total factor productivity during the study period from 2007 to 2011, which turned out to be 5% of annual decrease in productivity. The study found that the main reason of this decrease in total productivity is about 22% downward shift of a fisheries production function due to recent conditions of a devastated fishing ground. When we evaluated the statistical significance of changes in technical efficiency combining both pure technical and scale efficiency based on the 95% confidence intervals, we could not find any evidence of changes in those components of total factor productivity. When we accessed the productivity of the each of 15 adjacent water fisheries methods, only the large danish seine fisheries showed us about 7% increase in productivity. Even though the large trawling and the large tow-boat trawling revealed no changes in productivity, all of the other 12 fisheries suffered the decreases in productivities.