• Korean Journal of Remote Sensing
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• v.26 no.1
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• pp.21-27
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• 2010

This paper presents a numerical simulation of the radar backscattering from oil spills on ocean surface. At first, a one-dimensionally rough sea surface is numerically generated for a given wind speed at HEBEI SPIRIT accident. Then, an oil-spilled sea surface is represented with a two-layered medium, which is generated by adding a thin low-dielectric oil layer on the randomly-rough highdielectric sea surface. The backscattering coefficients of various oil-spilled sea surfaces are obtained using the Method of Moments and Monte Carlo technique for various surface roughness, oil-layer thicknesses, frequencies, polarizations and incidence angles. The numerical method is verified with theoretical models for simple structures. The reduction of the backscattering coefficients due to the lowdielectric oil-layers on sea surfaces has been analyzed. These numerical results will help to detect any oil spills on sea surfaces, and consequently, to classify SAR images.

• The Korean Journal of Nuclear Medicine
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• v.35 no.2
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• pp.100-112
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• 2001

Purpose: The purpose of this study was to establish optimal imaging acquisition conditions for the GE $Advance^{TM}$ PET imaging system by performing the acceptance tests designed by National Electrical Manufacturers Association (NEMA) protocol and General Electric Medical Systems (GEMS) test procedures. Materials and Methods: Performance tests were carried out with $^{18}FDG$ radioactivity source and phantoms by using a standard acquisition mode. Transaxial resolution and scatter traction tests were performed with a line source and axial resolution with a point source, respectively. A cylindrical phantom made of polymethylmethacrylate (PMMA) was used to measure sensitivity, count rate losses and randoms, uniformity correction, and attenuation inserts were added to measure remaining tests. The test results were acquired in a diagnostic acquisition mode and analyzed mainly on high sensitivity mode. Results: Transaxial resolution and axial resolution were measured as average of 4.65 mm and 3.98 mm at 0 cm, and 6.02 mm and 6.71 mm at 20 cm on high sensitivity mode, respectively. Average scatter fraction was 9.87%, and sensitivity was $225.8kcps/{\mu}Ci/cc$ of trues. Activity at 50% deadtime was $4.6{\mu}Ci/cc$, and the error of count rate correction at that activity was from 1.49% to 3.83%. Average nonuniformity for total slice w3s 8.37%. The accuracy of scatter correction was -0.95%. The accuracies of attenuation correction were 5.68% for air, 0.04% for water and -6.51% for polytetrafluoroethylene (PTFE). Conclusion: The results satisfied most acceptance criteria, indicating that the GE $Advance^{TM}$ PET system can be optimally used for clinical applications.

• Korean Journal of Poultry Science
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• v.50 no.1
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• pp.15-22
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• 2023

This study was to investigate the relationship between chick weight in the growing period and the laying performance of Korean native chicken (KNC) breeders. We measured the body weights of 1,384 KNC breeders at 1-140 days of age at two-week intervals. The age at first egg laying, hen-day and hen-housed egg production, and the egg weights were investigated. Correlation coefficients between the body weight and egg production traits were analyzed. The results showed that the correlation coefficients between body weight and age at first egg laying were significantly positive before 4 weeks, but negative after 8 weeks of age. The correlation coefficients between body weight and egg production rate were estimated to be negative before 8 weeks and positive after 12 weeks of age. Coefficients of hen-day and hen-housed egg production were similar. There was little correlation between body weight and egg weight at 32 weeks of age, whereas a low positive correlation was with egg weight at 50 weeks. In conclusion, there was little correlation between body weight and laying performance before 8 weeks of age, whereas a significant positive correlation was with body weight after 12 weeks. The results suggest that as the chick's weight increases in the late growing stage, sexual maturity is faster, the egg production rate is higher, and the egg weight increases. Therefore, the weight management of KNC female breeders is very important in the late growing stage, and the body weight of chicks must be maintained above the standard weight.

• Korean Journal of Poultry Science
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• v.33 no.3
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• pp.217-224
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• 2006

This study was carried out to investigate the effect of food-waste(FW) between weeks(0, 1, 2, 3, 4 week) and additive levels(0, 1, 3, 5, 10, 20%) on egg production and egg qualify in laying hens. One hundred sixty two White Leghorn laying hens at fifty weeks of age were used for this work. There was no significant difference on feed intake, egg production, and egg weight among all treatments. But, 20% FW group was decreased at 1, 2, and 3 week on egg production and it was recovered at 4 weeks(p<0.05). There was no difference on the eggshell thickness and egg yolk index among all treatments. However, eggshell breaking strength were $4.13kg/cm^2\;and\;4.04kg/cm^2$ at 3 week and 4 week, individually, and there was difference on eggshell breaking strength(p<0.05). Haugh unit and egg yolk color were high at 20% FW group as 92.3 and 9.4, individually, and there was shown the significant increasing in weeks and additive levels(p<0.05). Conclusionally, 20% FW group was decreased on egg production, while 5% FW group was maintained on egg production, and haugh unit and egg yolk color were cleary developed. Therefore, if the nutrients balance of FW diets were controlled, FW diets will be used with one of the valuable feed sources.

• Journal of Aquaculture
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• v.5 no.2
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• pp.117-126
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• 1992

Induced breeding and indoor rearing of the catfish, Silurus asotus were performed. Ovulation was induced by injection of 5 mg dried carp pituitary per kg body weight. Fertilization rates were $81.5\~98.0{\%}$ and hatching success was $67.0\~82.0{\%}$. There were no significant differences of daily growth rate (DGR) and food conversion ratio (FCR) between the groups fed extruded eel pellet and extruded carp pellet. No significant differences in DGR and FCR were also found between $3{\%}$ and $4{\%}$ daily feeding rates. DGR and FCR of small fry were slightly affected by dissolved oxygen (DO) level in aquaria. When the DO level maintained at $4.5\;mg/{\ell}$, the best result was obtained and DGR and FCR were $5.7{\%}$ and 0.65, respectively. At the higher level of DO, $5.5\;mg/{\ell}$, DGR and FCR were $5.52{\%}$ and 0.77, respectively, whereas at the lower level of DO, $3.5\;mg/{\ell}$, the DGR was decreased to $3.45{\%}$ and FCR was increased up to 1.01.

• Journal of radiological science and technology
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• v.37 no.3
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• pp.187-193
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• 2014

The purpose of this study was to analyze the effect on the selectivity on of high-voltage rectification device that measured the performance of the grid, and the contrast improvement ability (K factor) by measuring the scattered radiation content of the transmitted X-rays. The scattered radiation generated when the X-ray flux comes from the diagnostic X-ray generator that passes through an object. Targeting four different rectifications of X-ray generators, the mean value of the tube voltage and the tube current was measured in order to maximize the accuracy of the generating power dose within the same exposure condition. Using fluorescence meter, the content of the scattered rays that are transmitted through the acrylic was measured depending on the grid usage. When grid is not used, the content of the scattered rays was the lowest (34.158%) with the single-phase rectifier, was increased with the inverter rectifier (37.043%) and the three-phase 24-peak rectification method (37.447%). The difference of the scattered radiation content of each device was significant from the lowest 0.404% to the highest 3.289% while using 8:1 grid, the content of the scattered ray was the lowest with the single content of the scattered ray was the lowest with the single-phase rectifier (18.258%), was increased with the rectifier (25.502%) and the 24-peaks rectification (24.217%). Furthermore, there was difference up to content 7.244% to the lowest content 1.285% within three-phase 24-peaks rectification, inverter rectifications, and single-phase rectifier depending on the selectivity of the grid. Drawn from the statistical analysis, there was a similar relationship between the contrast improvement factor and the K factor. As a result, the grid selectivity and the contrast were increased within the single-phase rectifier rather than the constant voltage rectifier.

• KOREAN POULTRY JOURNAL
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• v.5 no.10 s.48
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• pp.57-72
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• 1973

1. 육추율, 육성율, 성계생존율 육추율은 99.9$\%$로서 1회 98.5$\%$, 2회 99.2$\%$, 3회 99.8$\%$, 4회 98.3$\%$, 5회 98.7$\%$, 6회 99.7$\%$와 비슷하였다. 육성율은 평균 98.8$\%$로서 1회 97.5$\%$, 2회 97.2$\%$, 3회 96.6$\%$, 4회 97.9$\%$와는 큰차가 없었고 5회 89.7$\%$ 6회 87.1$\%$ 보다는 약 12$\%$가 높게 나타났다. 이는 MD 백신접종 때문인 것으로 생각되며 성계생존율은 평균 86.3$\%$로서 87.3$\%$ 보다는 약 1$\%$낮았고 1회 80.3$\%$ 2회 84.8$\%$보다는 약 4.6$\%$ 높고 3회 71.8$\%$, 5회 71.4$\%$, 6회 75.3$\%$에 비하면 19$\%$나 높았다. 2. 성성숙일령 전체평균은 157.3일로 가장 빠른 구는 4구의 146일이고 가장 늦은 구는 10구와 17구의 161일이였다. 3. 산란율, 산란지수 산란율은 평균 62.0$\%$이고 가장 높은 구는 15구의 68.9$\%$ 이였다. 산란지수는 평균 205.1개로 1회 190.8, 2회 198.3, 3회 184.2, 5회 186.5, 6회 189.7개에 비하여 높고 4회때와 근사하였다. 4. 사료요구율 전체평균 3.23으로 1회 3.54, 2회 3.1과는 근사하나 3회 2.98, 4회 2.87 5회 2.83에 비하여 낮은 것은 사양표준은 작년도와 같으나 원료사료 특히 단백질 사료의 품질저하에 원인이 있었다. 5. 난평균 중량 검정계군 전체의 평균난중은 61.2g으로 최상위구는 64.70g, 최하위구는 58.3g이였다. 6. 체중 검정계의 전체의 평균제중은 300일령 1925.1g, 500일 1938.4g이며 유색품종은 300일령 1986.7g, 500일령 1948.4g이였다. 7. 사료섭취량 사료섭취량 평균은 1일수당 육추기 32.1g 육성기 73.0g 산란기 115.6g이었다. 8. 경제성 총 수입은 7,269,072.34으로 전체수입의 85$\%$가 계란수입이고 15$\%$는 폐계수입이었다. 지출은 5049,690으로 전체 지출의 99.95$\%$가 사료비 0.05$\%$가 초생추대이었다. 9. 후기 검정수수미달은 참고구로 처리하였고 축산시험장과 대천종축장에서는 당초부터 참고구로 출품하였다. 대신의 개리슨, 신기의 하바드 코메트는 수정율이 낮아서 검정수수가 미달되었으며 영국의 Sykes International Co. 에서 출품한 Sykes Tinted(WL$\times$RIR BX)는 출품회사에서 직접 종란을 항공편에 보내 인수 부화하여 검정하였다. 7회 부터는 초생추에 MD(뎁타백) 백신을 하여 초산전후에 폐사율이 적었으며 72년 11월부터 국산어분에 의한 염도의 과다에 의하여 약 2주일 설사를 하여 상당히 스트레스를 받은 바 있었다.

• The Journal of the Acoustical Society of Korea
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• v.32 no.2
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• pp.116-123
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• 2013

This paper represents generation of time-varying underwater acoustic channels by performing scattering simulation with time-varying ocean surface and Kirchhoff approximation. In order to estimate the time-varying ocean surface, 1D Pierson-Moskowitz ocean power spectrum and Gaussian correlation function were used. The computed scattering coefficients are applied to the amplitudes of each impulse of BELLHOP simulation result. The scattering coefficients are then compared with measured doppler spectral density of signal components which were scattered from ocean surface and the correlation time used in the Gaussian correlation function was estimated by the comparison. Finally, bit-error-rate and channel correlation simulations were performed with the generated time-varying channel based on passive time-reversal communication scenario.

• Korean Journal of Agricultural Science
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• v.28 no.2
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• pp.70-77
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• 2001

A preliminary experiment was conducted to produce fowl-typhoid resistant egg type breeds, using three brown egg layer breeders (ISA, Hyline, and Lohman) and two white egg layer breeders (ISA and Lohman). Various economic parameters were measured from day-old to mature stages using parent stocks of each breed. No significant difference in viabilities of mature hens from 34 to 66 wk of ages was found between brown(93.3%) and white(93.5%) egg layer breeders (P>0.05). Also, there was no difference in viabilities of mature cockerels. Although not significant, the mature body weights of brown egg layer breeders tended to be heavier than those of the white egg layer breeders both in hens and cockerels. No difference in feed intakes of mature brown and white hens were detected. Ages of sexual maturity of white and brown egg layer hens were 147.7 and 140.5 d, respectively (P<0.05). Egg production of white egg layer hens during 23-66 weeks age was significantly higher than their counterpart (81.4% vs. 75.0%). Comparisons of Haugh Unit, egg shape index, yolk color, and egg weight between brown and white eggs were not significantly different; however, the brown eggshells were thicker and stronger than those of white eggs (P<0.05).

• Korean Journal of Poultry Science
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• v.33 no.2
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• pp.127-131
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• 2006

This study was conducted to investigate the effects of expanding feed processing technologies on the egg characteristics and nutrient digestibility in laying hens. A total of two hundred seventy laying hens were randomly allocated into three treatments with fifteen replications for six weeks. Dietary treatments include 1) MS(mash), 2) EC(expanded crumble) and 3) EP(expanded pellet). In the egg production, the EC and EP treatments were significantly higher than MS treatment(p<0.05). However, no significant difference was founded in egg weight(p>0.05). Egg shell breaking was increased in EC and EP treatments compared with MS treatment(p<0.05), however, egg shall thickness showed no significant difference(p>0.05). Egg production and egg shell breaking were significantly higher in EC and EP treatments than MS treatment(p<0.05), but egg weight and egg shell thickness were no significantly difference among treatment(p<0.05). Yolk color was increased in EC treatment compared with other treatments(p<0.05). Also, yolk index was significantly improved in EC and EP treatments compared with MS treatment(p<0.05). Haugh unit was increased in EC treatment compared with MS treatment(p<0.05). EC treatment had improved DM, Ca and P digestibility. In conclusion, Expanded crumble and pellet processing could improve the egg characteristic and nutrient digestibility in laying hens.