• Korean Journal of Poultry Science
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• v.46 no.3
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• pp.193-204
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• 2019

This study aimed to investigate the changes in production performance of five strains of Korean native chickens (KNCs), which have been collected and established at the National Institute of Animal Science, Korea, since 1992. A total of 38,026 KNCs were tested and survival rate, body weight, age at first egg-laying, hen-housed egg production, and egg weight was analyzed. The mean survival rates of KNCs were $87.9{\pm}0.8%$, but no significant difference in survival rate between strains and in the annual survival rates of KNCs was observed. The average body weight of KNCs was $1,609.7{\pm}21.3g$ at 150 d. The average body weight of KNC-Black was the highest, whereas KNC-White had the lowest weight. A gradual increase in the annual weight change has been observed in almost all strains after 2004. The average age at first egg-laying was $146.9{\pm}1.1d$ in KNCs where KNC-White was the earliest and KNC-Black was the latest. The age at first egg-laying has increased after 2003, but has gradually decreased after 2008. The average hen-housed egg production at 270 d was $77.3{\pm}1.7$ in KNCs, wherein KNC-Yellowish brown was the highest and KNC-Black was the lowest. The average egg weight at 270 d was $51.2{\pm}0.3g$ in KNCs, indicating that KNC-Black was the heaviest, whereas KNC-White was the lightest. A significant increase in annual egg weight has been observed since 2008. To conclude, the appearance and feather colors of KNCs have improved uniformly, and the body weight has also improved slightly since 2002.

• Progress in Medical Physics
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• v.25 no.1
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• pp.37-45
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• 2014

The accuracy and uniformity of CT numbers are the main causes of radiation dose calculation error. Especially, for the dose calculation based on kV-Cone Beam Computed Tomography (CBCT) image, the scatter affecting the CT number is known to be quite different by the object sizes, densities, exposure conditions, and so on. In this study, the scatter impact on the CBCT based dose calculation was evaluated to provide the optimal condition minimizing the error. The CBCT images was acquired under three scatter conditions ("Under-scatter", "Over-scatter", and "Full-scatter") by adjusting amount of scatter materials around a electron density phantom (CIRS062, Tissue Simulation Technology, Norfolk, VA, USA). The CT number uniformities of CBCT images for water-equivalent materials of the phantom were assessed, and the location dependency, either "inner" or "outer" parts of the phantom, was also evaluated. The electron density correction curves were derived from CBCT images of the electron density phantom in each scatter condition. The electron density correction curves were applied to calculate the CBCT based doses, which were compared with the dose based on Fan Beam Computed Tomography (FBCT). Also, 5 prostate IMRT cases were enrolled to assess the accuracy of dose based on CBCT images using gamma index analysis and relative dose differences. As the CT number histogram of phantom CBCT images for water equivalent materials was fitted with a gaussian function, the FHWM (146 HU) for "Full-scatter" condition was the smallest among the FHWM for the three conditions (685 HU for "under scatter" and 264 HU for "over scatter"). Also, the variance of CT numbers was the smallest for the same ingredients located in the center and periphery of the phantom in the "Full-scatter" condition. The dose distributions calculated with FBCT and CBCT images compared in a gamma index evaluation of 1%/3 mm criteria and in the dose difference. With the electron density correction acquired in the same scatter condition, the CBCT based dose calculations tended to be the most accurate. In 5 prostate cases in which the mean equivalent diameter was 27.2 cm, the averaged gamma pass rate was 98% and the dose difference confirmed to be less than 2% (average 0.2%, ranged from -1.3% to 1.6%) with the electron density correction of the "Full-scatter" condition. The accuracy of CBCT based dose calculation could be confirmed that closely related to the CT number uniformity and to the similarity of the scatter conditions for the electron density correction curve and CBCT image. In pelvic cases, the most accurate dose calculation was achievable in the application of the electron density curves of the "Full-scatter" condition.

• Journal of Sericultural and Entomological Science
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• v.13 no.2
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• pp.119-122
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• 1971

The following results were obtained through the experiments and study of fertility for silkworm eggs in vagina, oviduct, and ovarial base. The sample eggs were collected after leaving silkworm moth for one week from the date of treatment was given to oviporm orifice of the silkworm moth by heated needle in order to discontinue laying eggs. Those sample silkworm moths were divided into two groups. The first group was under the condition of immediately after the couplation and the second group was under the condition of after the laying eggs in some extend, and both of them were completed couplation. The sample eggs were screened in order to confirm the degree of color which normally be observed as very characteristic during hibernating. 1. About 5% of silkworm out of the total sample were identified as having 1-2 eggs. (See table 1). But, the charasteristic colour of hibernating egg was not observed. The colour was not much different as that of eggs in ovarian duct. 2. Immediately after the couplation, the eggs were not found in vagina under the condition of immediately after the couplation. 3. About 10% of the sample under the condition of after laying eggs in some extend were found having eggs in vagina or oviduct. 4. About 2% of the sample silkworm moth under the condition of immediately after the couplation were found having I fertilized egg in oviduct. 5. No fertilized egg was found in ovarian tube. It seemed that sperm did not enter ovarian tube. 6. Almost the entire eggs were found in ovarian tube under the condition of immediately after the couplation. But, eggs under the condition of after laying eggs in some extend were found around oviduct and vagina due to the continuous movement of silkworm eggs towards oviporus orifice. 7. Sperm is mainly found around seminal receptacle and vagina, and sperm goes into micropyle together with silkworm eggs which were moving towards oviduct.

• Korean Journal of Poultry Science
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• v.36 no.4
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• pp.293-300
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• 2009

The rate of fetus with abnormal chromosomes increase with maternal age. Nondisjunction of aging oocyte chromosome is a major reason for the increased rate of abnormalities. Telomeres are the ends of eukaryotic chromosome, which are essential for chromosome stability and are related in cell senescence. This study was carried out to analyze the chromosome aberration rate and amount of telomeric DNA in chick embryo along with maternal age. Fertilized eggs and blood were sampled from White Leghorn layers starting at 20 weeks through to 70 weeks age at 10 weeks interval. Chromosome aberration rate was analyzed by karyotyping. The amounts of telomeric DNA in embryonic cells and lymphocytes were quantified by Quantitative Fluorescence in situ Hybridization method. The chromosome aberration rate in chick embryos significantly differed with maternal age. The chromosome aberration rate increased at early laying period and beyond 70 weeks of maternal age. Therefore, chromosome aberration rate was affected by maternal age due to ovulated oocytes state. However, the amount of telomeric DNA on embryonic cells did not differ significantly with maternal age. Thus, maternal age does not affects telomere quantity in their embryos due to cellular reprograming at early embryonic stage after fertilization.

• Korean Journal of Poultry Science
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• v.51 no.2
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• pp.83-95
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• 2024

This study aimed to assess the performance of laying hens across twelve crossbreed strains (i.e., CFCK, CFYC, CFYD, CKCF, CKYC, CKYD, YCYD, YCCF, YCCK, YDCF, YDCK, and YDYC) of Korean native chicken (KNC) and compare them with Hy-Line Brown layers. A total of 287 18-week-old laying hens were placed in battery cages by strains (2-5 birds per pen). Results indicated that the YCYD and YDYC strains exhibited numerically heavier body weights than Hy-Line Brown at week 18-64. CKYC and YDYC strains demonstrated more than 94% viability by week 64. The CFYC strain had an age of first egg laying of 127 days, and the YDCF strain reached an age of 50% egg production at 140 days, both earlier than their parent stock. The YDCF strain showed over 70% egg production for up to 60 weeks. Regarding egg quality, the CKCF and YCCF strains had numerically higher egg weights among the KNC groups at week 24-64, with the YDYC strain showing a darker (P<0.05) eggshell color compared to CKCF at week 40. Moreover, KNC crossbreeds showed a higher (P<0.05) egg yolk ratio than Hy-Line Brown. In conclusion, the YDCF and YCCF crossbreeds exhibited the most desirable new synthetic Korean native commercial layer based on egg production and quality parameters. Therefore, these strains could be a viable substitute for Hy-Line Brown layers.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.483-484
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• 2001

갯벌 생태계는 우리나라의 가장 중요한 습지생태계의 일부분으로 많은 해양생물에게 있어서 중요한 서식처이다. 한반도 서ㆍ남해안에 광활하게 펼쳐진 갯벌은 해양생물의 산란장으로서,다양한 생물들이 생활사중 일부, 특히 어린시기에 보육장으로 그리고 성육장으로 이용하고 있다. 그럼에도 불구하고 지금까지 갯벌에 대한 관심은 저서동물의 군집구조, 시ㆍ공간 및 우점종의 분포양상에 치중한 면이 우세하고, 비교적 최근에 들어 다양한 기능들에 대한 연구들이 수행중에 있다. (중략)

• Korean Journal of Poultry Science
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• v.12 no.1
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• pp.1-6
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• 1985

To secure a higher percentage of fertility in hatching eggs and a higher percentage of hatchability of the fertile eggs should be of direct benefit to poultry breeder ana hatchery operators. This study was carried out to estimate the relationships of egg production and fertility in broiler breeder. The data analysed were the record of pullets (5 strains) of broiler breeder raised at Poultry Breeding Farm, Seoul National Univ. from 1982 to 1983. Since the purpose of the study was only to find out the relationships between egg Production and fertility, many other factors thought to be included in fertility were fixed as much as possible. The results were summarized as follows. 1. Mean figure of egg production rate and fertility from 30 weeks age to 60 Weeks of age to 60 weeks of age were 60.5-65.2 percent and 82.7-87.9 percent. 2. Correlation coefficients between egg Production rate and fertility were high and positive, except line K, and the coefficients have highly significant differences. 3. Regression coefficients of fertility on egg Production rate were 0.54-0.97, except line K. 4. Maximum fertility age estimated from the polynomial regression equation were 44-47 weeks. The results obtained in this study suggested that the selection of high performance strain in egg Production should improve the fertility.

• Korean Journal of Ichthyology
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• v.12 no.1
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• pp.62-70
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• 2000

Annual reproductive cycle of the file fish, Stephanolepis cirrhifer (Temminck et Schlegel), was histologically investigated. Samples were collected monthly in the coastal waters of Chungmun, south of Cheju Island, Korea from July 1997 to June 1999. In males and females of S. cirrhifer, the values of GSI (gonadosomatic index) were similar to the changes of water temperature and day length. GSI values in males and females were reached the maximum in June. Reproductive cycle could be divided into the following successive stages: in females, growing stage (February to May), mature stage (May to June), spawning stage (June to August), degenerative and resting stage (September to December), and in males, growing stage (February to April), mature stage (May to June), spent stage (June to August), degenerative and resting stage (September to January), respectively. Throughout histological observation of the ovary in the spawning period, the species belong to an asynchronous and multiple spawner.

• Korean Journal of Ichthyology
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• v.23 no.4
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• pp.300-304
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• 2011

The reproductive characteristics of Chaenogobius gulosus was examined using 333 specimens collected monthly between October 2008 and September 2009 in the coastal waters of Tongyoung, Korea. Specimens ranged from 2.0 to 12.6 cm in standard length (SL). The gonadosomatic index (GSI) of females was highest in February and decreased until April, with the spawning season lasting from December to April. The monthly ratio of female to male did not significantly differ (${\chi}^2$-test, p>0.05). The size at 50% maturity for females was 7.9 cm SL. Fecundity ranged from 1,112 to 6,059 eggs, with a mean of 3,011 eggs.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.2
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• pp.140-148
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• 2002

The primary goal of this study is to determine the distribution characteristics using a scientific echo sounder in the Yellow Sea west of South Korea. The survey was carried out between 33$^{\circ}$00'N~37$^{\circ}$00'N latitude and 124$^{\circ}$00'E~126$^{\circ}$00'E longitude during the months of May and August, 1999 and April, 2000. The ships used in this survey were the R/V Chung-kyeong(G/T 300) and R/V Dong-baek(G/T 1,050) of Yeosu National University. The results obtained are as follows : 1. From the oceanographic data the Yellow Sea were divided into three sea areas which were the western waters of Chejudo, Mokpo and Kunsan. The oceanographic conditions were different in each of these three areas and the western waters of Chejudo were higher about 1~5$^{\circ}C$ more than the western waters of Gunsan. Generally, thermoclines were presented clearly in all three areas, but more so in August than in May according to seasons. 2. The horizontal distribution of S$_{A}$(area backscattering coefficient per unit area) value is that the western sea waters of Chejudo area are higher than that of the western sea waters of Mokpo and Gunsan. 3. The vortical distribution of S$_{A}$ value varies with thermocline that the harder thermocline is, the higher the S$_{A}$ value is. 4. The S$_{A}$ values on the types of biomass distribution are different with frequency. At the 38kHz, the demersal schools have higher values than the pelagic schools. At the 120kHz, the pelagic schools have higher values than the demersal schools.