• 한국도로학회:학술대회논문집
• /
• 2005.11a
• /
• pp.177-182
• /
• 2005

• Composites Research
• /
• v.32 no.1
• /
• pp.78-84
• /
• 2019

This study focused on the prediction of the long-term performance of carbon fiber/epoxy composites using Dynamic Mechanical Analysis (DMA) and Time-Temperature Superposition (TTS). Single-frequency test, multi-frequency test, and creep TTS test were performed. A sinusoidal load of $20{\mu}m$ amplitude was applied while increasing the temperature from $-30^{\circ}C$ to $240^{\circ}C$ at $2^{\circ}C/min$ for the single-frequency test and the multi-frequency test. The frequencies applied to the multi-frequency test were 0.316, 1, 3.16, 10 and 31.6 Hz. In the creep TTS test, a stress of 15 MPa was applied for 10 minutes at every $10^{\circ}C$ from $-30^{\circ}C$ to $230^{\circ}C$. The glass transition temperature was determined by single-frequency test. The activation energy and the storage modulus curve for each temperature were obtained from glass transition temperature for each frequency by the multi-frequency test. The master curve for the reference temperature was obtained by applying the shift factor using the Arrhenius equation. Also, TTS test was used to obtain the creep compliance curves for each temperature and the master curve for the reference temperature by applying the shift factors using the manual shift technique. The master curve obtained through this process can be applied to predict the long-term performance of carbon fiber/epoxy composites for a given environmental condition.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.49 no.4
• /
• pp.360-367
• /
• 2013

The mesh selectivity of the gillnet for Pacific herring (Clupea pallasii) was examined in field experiments with four different mesh sizes (63, 69, 75 and 81mm) from June to July, 2013 in the coastal areas of Imwon in Gangwon province. The fishing performance tests were conducted with a commercial Pacific herring gillnet and a biodegradable gillnet for Pacific herring together selectivity tests. The filed tests were carried out the total 11 times. The master curve of selectivity was estimated by the extended Kitahara's method. In the results, the catch number of Pacific herring was 9,409 (2,203kg) and occupied 84.2% in total catches weight. The optimal mesh size for 50% retention on first maturity size (female, 250mm) of Pacific herring was estimated as 64.5mm by master selectivity curves. The fishing performance of the biodegradable gillnet was showed to be equivalent with commercial gill for Pacific herring.

• Tribology and Lubricants
• /
• v.23 no.4
• /
• pp.149-155
• /
• 2007

The CAD model of a elliptical gear for wire cutting has been developed. The rolling contact of pitch ellipses whose rotation axes coincide with their focus has been analyzed, and the perimeter of the pitch ellipse has been divided into equal-length segments by the number of teeth. A master tooth profile, which is a composite curve of circular arcs that represents involute, has been introduced. The elliptical gear has been designed by imposing the master tooth on the divided points of the pitch ellipse, and a full fillet has been achieved between neighbour teeth. Thus, the whole profile of an elliptical gear is a composite curve of arcs only, and consequently NC codes for wire cutting can be easily generated. Furthermore, a computer simulation program is developed to verify the mesh of the elliptical gear.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.11 no.1
• /
• pp.39-44
• /
• 2015

The fracture toughness of 2.25Cr-1Mo cast steel (SA217-WC9) samples which were taken from the check valves of feed water piping of Korean Standard Nuclear Power Plant(KSNPP) was measured by Master Curve method. The measured $T_0$ reference temperature of SA217-WC9 steel was $-30^{\circ}C$. The obtained $T_0$ was compared to the derived value from Charpy impact test data following to SINTEP procedure. The heat-to-heat variation in fracture toughness of SA217-WC9 steel was observed. It was found that the low toughness of a heat of SA217-WC9 steel was attributed to the coarse MnS inclusion originated by high sulfur content as the results of microanalyses.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.2 s.173
• /
• pp.303-310
• /
• 2000

Fracture toughness of five different reactor pressure vessel steels was characterized in the transition temperature region by the ASTM E1921-97 standard method using Charpy-sized small specimens. T he predominant fracture mode of the tested steels was transgranular cleavage in the test conditions. A statistical analysis based on the Weibull distribution was applied to the interpretation of the scattered fracture toughness data. The size-dependence of the measured fracture toughness values was also well predicted by means of the Weibull probabilistic analysis. The measured fracture toughness transition curves followed the temperature-dependence of the ASTM master curve within the expected scatter bands. Therefore, the fracture toughness characteristics in the transition region could be described by a single parameter, so-called the reference temperature (T。), for a given steel. The determined reference temperatures of the tested materials could not be correlated with the conventional index temperatures from Charpy impact tests.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.59 no.2
• /
• pp.99-109
• /
• 2023

In this study, a comparative test operation was conducted through the alternate haul method to examine the selectivity of the four mesh sizes (60 mm, 90 mm, 110 mm, and 130 mm) of the trawl codend. The selectivity was analyzed using the SELECT model considering the fishing efficiency (split parameter) of each fishing gear in the comparative test fishing operation in the trawl and the maximum likelihood method for parameter estimation. A selectivity master curve was estimated for several mesh sizes using the extended-SELECT model. As a result of analyzing the selectivity for silver croaker based on the results of three times hauls for each experimental gear, it was found that the size of the fish caught increased as the size of the mesh size increased. When the selectivity for each mesh size analyzed by the SELECT model considering the split ratio was evaluated based on the size of the AIC value, the estimated split model was superior to the equal split model. Based on the master curve, the 50% selection length value was 2.893, which was estimated to be 136 mm based on the mesh size of 60 mm. In some selectivity models, there was a large deviance between observed and theoretical values due to the non-uniformity of the distribution of fished length classes. As a result, it is considered that appropriate sea trials and selectivity evaluation methods with high reliability should be applied to present trawl fishery resource management methods.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.40 no.1
• /
• pp.86-94
• /
• 2004

This study was conducted to mesh selectivity of Beam trawl for shrimps fishing experiment in the coastal waters around Geomundo, South sea of Korea, during from Oct. to Nov. 2002. The selectivity parameters of big head shrimp (Solenocera melantho) have been studied on the covered con-end method. with mesh of 8, 38, 51 and 61 mm. Selection curves and selection parameters were calculated by using a logistic function S=1/(1+exp-(aCL+b)). The mesh selection master curves were estimated by S=1/(1+exp$^{({\alpha}(CL/M)+{\beta}}$), and the optimum mesh size were calculated with (L/M)50 of master curve. Optimum mesh size and selectivity master curves for the southern rough shrimp (Yrachysalambria curvirostris) and smoothshell shrimp (Parapenaeopsis tenella) optimum mesh size and selectivity master curves were estimated by big head shrimp master curves. The results obtained are summarized as follows : Selection parameters '${\alpha}$' and '${\beta}$' of the master curve for big head shrimp were 8.84 and -5.89, and The selection factor of the master curve (L/M)$_{50}$ was 0.67. The optimum mesh size of minimum length for sexual maturity for big head shrimp was 30.7 mm. Estimated (L/M)$_{50}$ for southern rough shrimp and smoothshell shrimp by using the master curve of big head shrimp was 0.73 and the optimum mesh sizes were 25.5 mm for southern rough shrimp and 16.9 mm for smoothshell shrimp, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.29 no.4
• /
• pp.247-259
• /
• 1993

The fishing experiment was carried out by the training ship Saebada in order to analyse the mesh selectivity for trawl cod-end, in the Southern Korea Sea and the East China Sea from June. 1991 through August, 1992. The trawl cod-end used in this experiment has the trouser type of cod-end with cover net. and the mesh selectivity was examined for the five kinds of the opening of mesh in its cod-end part. A total of 163 hauls, of which having mesh size 51.2mm ; A 89, 70.2mm ; B 54, 77.6mm ; C 55, 88.0mm ; D 52 and 111.3mm ; E 20 were used respectively. Selection curves and selection parameters were calculated by using a logistic function, S=1/(1+exp super(-(aL+b)) ). The mesh election master curves were estimated by S=1/(1+exp super(-[a(L/M)+$\beta$]) ). and the optimum mesh size were calculated with (L/M) sub(50) of master curve. In these cases 'a' and '$\alpha$' are slope, 'b' and '$\beta$' are intercept. 'L' is body length of the target species of fishes, 'M' is the mesh size, and 'S' denotes mesh selectivity. In this report, the four species of compressed form fishes were taken analized according to fish shape, and 'S' denotes mesh selectivity. In this report, the four species of compressed form fishes were taken analized according to fish shape, and the results obtained are summarized as follows: 1. Red seabream Pagrus major(Temminct et Schlegel) and yellow porgy Dentex tumifrons(Temminct et Schlegel) ; Selection rate in each mesh size of A, B, C, D and E were 99.7%, 97.5%, 91.4%, 76.7% and 57.8% respectively. Selection parameters 'a' and 'b' of mesh sizes C, D and E were 2.65 and -28.62, 4.40 and -77.73, 2.31 and -46.99, and their selection factors were 1.39, 2.10, 1.83 respectively. Selection parameters of master curve '$\alpha$' and '$\beta$' were 3.05 and -5.65 respectively, and (L/M) sub(50) was 1.85. The optimum mesh size of Red seabream was 141mm. 2. Filefish Thamnaconus modestus (Gunther) ; Selection rate in each mesh size of A, B, C, D and E were 99.6%, 98.3%, 91.2%, 80.0% and 48.6% respectively. Selection parameters 'a' and 'b' of mesh sizes C, D and E were 5.82 and -55.10, 2.92 and -36.90, 3.91 and -63.09, and their selection factors were 1.35, 1.44, 1.45 respectively. Selection parameters of master curve '$\alpha$' and '$\beta$' were 3.02 and -4.32 respectively, and (L/M) sub(50) was 1.43. The optimum mesh size was 129mm. 3. Target dory Zeus faber Valenciennes ; Selection rate in each mesh size of A, B, C, D and E were 99.7%, 100%, 83.2%, 91.6% and 65.0% respectively. Selection parameters 'a' and 'b' of mesh sizes C, D and E were 3.85 and -32.46, 4.19 and -57.38, 2.45 and -40.03, and their selection factors were 1.09, 1.56, 1.47 respectively. Selection parameters of master curve '$\alpha$' and '$\beta$' were 2.64 and -3.53 respectively, and (L/M) sub(50) was 1.34. The optimum mesh size was 127mm. 4. Butterfish Psenopsis anomala (Temminct et Schlegel) ; Selection rate in each mesh size of A, B, C, D and E were 99.2%, 34.1%, 46.5%, 14.3% and 2.4% respectively. Selection parameters 'a' and 'b' of mesh sizes B, C and D were 5.35 and -71.70, 5.07 and -69.25, 3.31 and -62.06 and their selection factors were 1.91, 1.75, 2.13 respectively. Selection parameters of master curve '$\alpha$' and '$\beta$' were 3.16 and -6.24 respectively, and (L/M) sub(50) was 1.98. The optimum mesh size was 71mm.

• Proceedings of the KIEE Conference
• /
• 2005.05a
• /
• pp.269-271
• /
• 2005

EMV was formed in February 1999 by Europay International, MasterCard International and Visa International to manage, maintain and enhance the EMV Integrated Circuit Card Specifications for Payment Systems as technology advances and the implementation of chip card programs become more prevalent. The formation of EMV ensures that single terminal and card approval processes are developed at a level that will allow cross payment system interoperability through compliance with the EMV specifications. A credit card environment of the domestic market adopted the standard Local-EMV to have the compatibility with EMV international standard and the EMV migration have been carried out b,# the step-by-step process. It may be possible to adopt various kinds of cryptographic algorithms, however, RSA public key algorithm is currently used. In this paper, as a public key algorithm for the authentication process, Elliptic Curve Cryptographic algorithm is applied to the EMV process. Implementation results is shown. and the possible changes necessary to accommodate Elliptic Curve Cryrtography is proposed.