• Korean Journal of Ichthyology
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• v.33 no.2
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• pp.64-73
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• 2021

We examined the growth and age structure for chub mackerel caught by a large purseseine in the Korean waters from January to December 2015. A total of 459 specimens were used for otolith analysis, ranging from 19.6 cm to 46.0 cm in fork length. Translucent zone was regarded as an annual mark, and age was counted using the information of the number of translucent zone, capture date, edge type of the otolith and nominal birthdate of 1 January. Annuli in otoliths were mainly formed in May, coinciding with the spawning season. Estimated ages were 0~6 years, and the von Bertalanffy growth models were not significantly different between male and female. Sex-combined growth model was obtained as FL_t=39.3×{1-exp[-0.90×(t+0.033)]}. Among the chub mackerel caught in 2015, the age 2 group had the highest proportion (30.9%), and the age 0 to 2 group accounted for 88.5% of the total catch.

• 한국문화재보존과학회:학술대회논문집
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• 2007.05a
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• pp.39-40
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• 2007

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.199-204
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• 1998

To analysis the failure character of Low-Heat concrete which is used to prevent the thermal crack caused by hydration heat, static loading test was performed by this test method, "Determination of the Fracture Energy of Motar and Concrete by Means of Three-Point Band Tests on Notched Beam" (suggested by RILEM 50-FMC Committe). This study compared and analysised the fracture energy of Mode I (opening mode), the most general pattern in the view of water-cemente ratio(W/C), compressive strength and age of Ordinary Portland Concrete and Low-Heat Concrete under the same mixture. The test results show that the case of Ordinary Portland Concrete and Low-Heat Concrete, low Water-Cemente ratio(W/C) cause the increase of fracture energy, and high failure-strength decrease failure-deflection, and the fracture energy of Low-Heat Concrete is similar to Ordinary Portland Concrete as the age increase. increase.

• Journal of Forest and Environmental Science
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• v.31 no.3
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• pp.202-206
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• 2015

Site index curves were developed for Larix kaempferi and Pinus koraiensis in Gangwon and North Gyeongsang provinces in Korea. For the development of site index, Schumacher and Chapman-Richards model were applied using the data collected from 2012 to 2014. Base age was set to 40 years for Larix kaempferi and Pinus koraiensis in site index of this study. Coefficient of determination and root mean square error of site index models were provided by species, and the models were compared with the previous studies to check the suitability. Overall, site index models developed in this study fitted in the current data well. Thus, the site indexes are considered to be properly used in Gangwon and North Gyeongsang provinces.

• Analytical Science and Technology
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• v.17 no.3
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• pp.271-277
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• 2004

The aim of this study was to investigate questioned documents written with blue or black ballpoint pen on paper by nondestructive technique. In this work, 21 blue and 22 black ballpoint pen inks which were purchased on different brands were analyzed by using Microspectrophotometry (MSP). The reflectance spectra were obtained from these ink samples and their shapes and the wavelength of the maximum intensity were compared. In the blue and black ballpoint pen inks, the discriminating powers (DP) were 0.85 and 0.61, respectively. The changes of the reflectance intensity at their wavelength of maximum intensity and their shapes appeared according to the exposure time to sunshine in a laboratory, especially in the blue ballpoint pen inks. Therefore it is possible to distinguish ink entries on the same paper with the relative age in case of questioned letters written with blue ballpoint pen.

• Journal of the Korean Society for Railway
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• v.6 no.4
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• pp.265-272
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• 2003

The computer program for the accelerated life testing technique of a machine part under the service conditions is developed under the GUI environment so that the user can easily obtain the results by selecting the program module. Also, the theoretical backgrounds for the computer program and the procedures of the accelerated testing method are introduced by testing the specimens made of the stainless steel 316L under the high temperature and random loading. The reliability of the program is discussed by the experimental results of the fatigue life, age degradation and accelerated testing conditions.

• Korean Journal of Veterinary Research
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• v.23 no.1
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• pp.1-8
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• 1983

The purpose of the present study is to determine variations in synthesis of DNA in the nuclei of various elements of the golden hamster (Mesocricetus auratus) placenta with increasing gestational age from the eighth day post coitus to parturition. The method employed for such determination was autoradiography following injection of pregnant animals with tritiated thymidine. From the results reported, the following points are concluded. The mitotic activities of the endodermal cells of the visceral yolk sac and of the parietal yolk sac, the trophoblastic cells of the labyrinth and the trophospongium and the giant cells were decreased with increasing gestational age, The placentation was nearly completed by day 13 of pregnancy and the increase in size of labyrinth was by appositional growth from the trophospongial cells. It was considered that the inner trophoblastic cells in the vicinity of the fetal blood vessels were originated from the pure chorion. The interrelation among the various cells and the polyploidal giant cells in the placenta were discussed.

• Journal of Applied Reliability
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• v.17 no.4
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• pp.316-324
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• 2017

Purpose: The purpose of this study is to determine the replacement cycle applied age replacement policy by reliability analysis based on railway vehicle contactor's failure history data. Method: We performed reliability analysis based on railway vehicle contactor's failure history data. We found a suitable distribution by goodness of fit test and predicted the reliability through estimation of scale & shape parameter. Considering cost information we determined the replacement cycle that minimize the opportunity cost. Result: Suitable distribution was the Weibull and scale parameter & shape parameter are estimated by reliability analysis. The replacement cycle was predicted and MTTF, $B_6$ percentile life were suggested additionally. Conclusion: We confirmed that failure rate type of railway vehicle contactor is degradation model having a time dependent characteristic and examined the replacement cycle in our country's operating environment. We expect that this study result contribute to railway operation agency for maintenance policy decision.

• Korean Journal of Poultry Science
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• v.21 no.3
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• pp.175-182
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• 1994

An experiment was conducted to establish a large scale production method of anti-serum against chicken IgM and to profile the developmental changes of serum IgM levels during the feeding period(from hatching to 7 weeks of age) in broiler chicks. Blood samples were taken from Hubbard chicken at the age of hatching, three days of age, and weekly thereafter till to 7 weeks of age. The pure IgM was isolated from ammonium sulfate treated chicken serum by both sephadex G-200 and sepharose CL-6B chromatography. The breaking-through peak containing IgM appeared from the fraction 26 to 28. These fractions consisted mainly of IgM when tested by anti-chicken IgM(Nordic, Netherlands). Immunized with the heavy chain of this purified IgM, the rabbit immune sera(anti-chicken IgM) were formed a reaction only with the purified chicken IgM. The quantitative assay of serum IgM were carried by RID method. The optimal time for diffusion was 14 hours and the coefficient of determination($R^{2}$) for regression equation of standard curve was 0.992. It was observed that IgM concentrations were the highest at hatching(3.23 mg /mL), after that decreased gradually. From 2 to 5 weeks of age the levels unchanged(2.0 ~ 2.3mg /mL), and gradually decreased to 7 weeks of age(1.3 mg /mL).

• Korean Journal of Ichthyology
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• v.5 no.2
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• pp.177-183
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• 1993

Results comparing the scale and otolith ages for walleye pollock from the Donut Hole of the Bering Sea showed a significant discrepancy for fish older than 8 years old. For walleye pollock from the Shelikof Strait of the Gulf of Alaska, comparison between ages determined from the scale and otolith readings indicated that there were no differences for younger age groups, but for the ages 6 and older, discrepancies squeezed in somewhat amid the same age groups.