• 대한조선학회지
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• 제23권4호
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• pp.1-10
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• 1986

A container ship, due to wide hatch openings, has characteristics of poor torsional rigidity, strong coupling of horizontal-torsional modes and significant discontinuity in the longitudinal variation of hull sections. In the mathematical formulation of the problem the hull is modeled as a beam and the transfer matrix method is utilized. The cross decks between cargo hatch opening are separated from the main hull and regarded as equivalent springs restraining torsion of hull. The effect of shear deformation of ship-side plating on torsion is taken into account in addition to St. Venant's and bending torsional rigidities. Compatibility requirements at cross section discontinuity are approximately considered. Developing the practical calculation procedure and the computer programs for application to an actual ship, some parametric studies on modeling methods of the cross deck, the compatibility condition, added-mass center etc. are out for the purpose of comparison.

• Journal of Welding and Joining
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• 제34권4호
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• pp.28-33
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• 2016

The purpose of this study is to evaluate the redistribution of transverse residual stress in the multi-pass FCA butt weld of YP47 in the hatch coaming top plate of ultra large size containership under the tensile cyclic load. In order to do it, the configuration of modified H type specimen including restraint length was first designed to simulate the restraint condition of the butt weld in hatch coaming top plate. FE analysis procedure for evaluating the transverse residual stress was verified by comparing the calculated mean and surface residual stresses with the measured results in the test specimen. After that, the effect of the cyclic load on the redistribution of transverse residual stress was evaluated by comprehensive FEA. From the results, it was found that although the maximum transverse residual stress decreased with an increase in the applied maximum load, the effect of the cyclic load on the mean residual stress is small enough to be negligible. It is because the maximum stress of the ship corresponding to the probability of 10E-8 is less than 70% of yield stress of the weld.

• International Journal of Industrial Entomology and Biomaterials
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• 제33권1호
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• pp.15-23
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• 2016

One major constraint in the development and implementation of a successful and cost-effective area-wide integrated pest management (AW-IPM) programme with a SIT component for Bactrocera oleae (Diptera: Tephritidae) is the ability to produce a large number of high quality mass-reared individuals. The aim of this study was to develop a more efficient and practical egg collection system in an attempt to improve the mass-rearing of this species. The following basic parameters were examined: egg production per female, egg hatch, pupal recovery, pupal weight, adult emergence and percentage of fliers. Three different strains (Israel wild-type, France wild-type, and Greece laboratory) were tested and each strain was evaluated for six generations. Female flies of the Israel strain produced significantly more eggs per female than the other two strains, but egg hatch was significantly lower. Egg hatch of the France wild type and the Greece laboratory strain was similar. For all other parameters, there was no significant difference between strains; however, there was a significant generational effect for all parameters observed. As a result of this study, a protocol was developed for the mass-rearing of this species that included the use of large adult holding cages that could house up to 96,000 flies per cage. The newly developed method of egg collection using a flat wax panel as one of the sides of an adult holding cage proved to be cost-effective, efficient, making colony growth easier for industrial mass-rearing.

• Asian-Australasian Journal of Animal Sciences
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• 제33권2호
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• pp.305-312
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• 2020

Objective: The present trial was conducted to determine the influence of different dietary fatty acid (omega-3 and omega-6) sources on reproductive performance of female broiler breeders and growth performance and carcass traits of their progeny. Methods: Two hundred and twenty, 25 weeks old Ross-308 male (20) and female (200) broiler breeders were used in the experiment for the period of 6 weeks. All birds were randomly divided into four dietary treatments (containing 2% soybean oil, 2% sunflower oil, 2% flaxseed oil, and 2% fish oil) each with five replicates of one male and ten females. Throughout this experiment hatching performance of broiler breeders, progeny growth performance and carcass parameters were recorded. Results: The results showed that the inclusion of different fatty acid sources in female broiler breeders diet had no significant effects (p>0.05) on number of fertile eggs, post-hatch mortality, and fertility rate. The soybean oil supplemented group had significantly (p<0.05) higher late embryonic mortality compared to other three treatments. Conclusion: It was concluded that inclusion of 2% of different sources of omega-3 and omega-6 fatty acids (especially 2% flax seed oil) in broiler breeders' diet can reduce late embryonic mortality. The other reproductive characteristics of parents and growth and carcass characteristics of progeny remained unaltered by dietary sources of omega-3 and omega-6 fatty acids.

• Animal cells and systems
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• 제12권4호
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• pp.287-295
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• 2008

Variations of larval abundance and hatch timing of Dungeness crabs, Cancer magister Dana 1852, were investigated. Dungeness crab larvae were monthly collected at 16 stations arrayed in four transects, Upper Chatham, Icy Strait, Cross Sound, and Icy Point, in southeastern Alaska from May to September 1997-2004. Larval abundance at all transects was the highest in June except in the Icy Point transect. Larval abundance was the highest in the Icy Strait transect, moderate in the Upper Chatham and Cross Sound transects, and the lowest in the Icy Point transect. Zoeae I(ZI) was predominated in May; thereafter ZI decreased and late zoeal stages occurred. In May and June, small numbers of late stage larvae unusually co-occurred with ZI in three transects. These late stage larvae may have been transported from where hatching occurs earlier. The timing of ZI occurrence varied interannually and was related to degreedays during the egg incubation period of Dungeness crabs: later larval hatching in 1997 and 2002 when temperatures were colder, while earlier larval hatching in 1998 when temperatures were warmer. The distribution patterns of Dungeness crab larvae in southeastern Alaska were markedly different from those reported from other areas of the species distribution ranges: larvae occurring much later in the year, and late stage larvae occurring in inland waters.

• 한국어류학회지
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• 제32권2호
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• pp.78-83
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• 2020

수온은 양식 대상어의 종자생산에 영향을 미치는 중요한 환경 요인이다. 본 연구는 최근 급격한 자원 감소를 보이고 있는 한해성 어종인 명태의 안정적인 종자생산을 위한 기초자료로 활용하기 위해 수온이 명태의 부화 및 초기 자어 성장에 미치는 영향을 조사하였다. 수정란의 생존율은 5℃가 8℃와 11℃에 비하여 높게 나타났으며, 부화율은 8℃에서 가장 우수하게 나타났다. 그러나 첫 부화, 50% 부화 및 완전 부화까지의 소요 시간은 11℃가 5℃와 8℃에 비하여 빠르게 나타났다. 12주간의 사육기간 동안 자어의 생존율은 5℃가 8℃와 11℃에 비하여 높게 나타났으나, 성장은 11℃가 5℃와 8℃에 비하여 높게 나타났다.

• Asian-Australasian Journal of Animal Sciences
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• 제18권4호
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• pp.524-531
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• 2005

Two experiments were conducted to standardize in ovo injection of amino acids (AA) and to evaluate the effect of in ovo injection of limiting AA(s) on pre and post hatch growth performance, immune response and development of digestive organs. Combinations of essential and non-essential amino acids (Lys+Arg, Lys+Met+Cys, Thr+Gly+Ser, Ile+Leu+Val and Gly+Pro) were injected into 50 eggs in each treatment group at 14 d of embryonic age. Standardization of injection site, needle length and embryonic age revealed that when AA were injected in to the broad end of the egg with a 11 mm needle and at the narrow end with a 24 mm needle both at the 7$^{th}$ and 14$^{th}$ d of incubation there was poor hatchability. However, better hatchability was recorded when the AA were injected in the narrow end of the egg with a 11 mm needle and in the broad end with a 24 mm needle on the 14$^{th}$ d of incubation. The chick to egg weight ratio was higher (p<0.018) when AA were injected on the 14$^{th}$ d of incubation. When a combination of amino acids were injected a 63.6 or 63.2 g difference in body weight of bird at 21 d was recorded between uninjected control and Ile+Leu+Val or Gly+Pro group, respectively. Higher feed intake (p<0.047) was recorded in the AA injected groups and feed conversion ratio (FCR) was numerically better in Gly+Pro, Lys+Met+Cys AA injected groups than in the uninjected control. Significantly higher immune response to cell mediated (p<0.033) and humoral (p<0.002) immunity was observed in in ovo amino acid injected birds, especially in Lys+Met+Cys, Thr+Gly+Ser or Ile+leu+Val groups. The digestive organ weights at 21 d did not differ between specific AA injected groups and the uninjected control. In ovo injected amino acids may act as immunomodulators and their role in gastrointestinal development needs further research.

• 한국패류학회지
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• 제19권2호
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• pp.107-110
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• 2003

The effect of broodstock age on the spawning performance of cultured abalone, Haliotis discus hannai, was assessed for five age groups (3, 4, 5, 6, 7 years old). Spawning performance of the five age groups was assessed in terms of the percentage of spawning abalone, eggs per spawning female, fertilization rates, hatch rates and attachment rates per spawning. The percentage of spawning abalone increased along with broodstock age, reached maximum in female groups of 5- and 6-year age (60%), and in male group of 6-year age (100%), subsequently decreased in 7-year age group. The number of eggs produced per spawning also increased with broodstock age, and the maximum was found in 6-year age. Although the number of spawned eggs for the oldest abalone declined, it still spawned much more eggs than 3, 4, and 5 years old females. The fertilization and hatch rates were obviously larger for 4-6 years old group than the younger and older abalones. The maxima were found in 5-year age group (96.0% and 84.5%), and the minimum were appeared in 7-year age group (79.3% and 58.2%). The attachment rate increased with broodstock age, reached maximum in 6-year age group (33.6%), although the increment gradually declined. The attachment rate for 7-year age group rapidly decreased (16.6%). These results suggested that broodstock age affected the spawning performance of H. discus hannai, which peaked between 5 and 6 years old, and broodstock should be bred during this period for hatchery production.

• 한국해양공학회지
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• 제34권2호
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• pp.120-127
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• 2020

Evaluation of fatigue strength considering the springing effect of very large container ships is crucial in the design stage. In this study, we established a fatigue strength evaluation method considering a linear springing component in the frequency domain. Based on a three-dimensional global model, a fluid-structure interaction analysis was performed and the modal superposition method was applied to determine the hot spot stress at the hatch corner of very large container ships. Fatigue damage was directly estimated using the stress transfer function with a linear springing response. Furthermore, we proposed a new methodology to apply the springing effect to fatigue damage using hull girder loads. Subsequently, we estimated the fatigue damage contribution due to linear springing components along the ship length. Finally, we discussed the practical application of the proposed methods.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.165-166
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• 2006

Surface pattern of tribological applications is an attractive technology of engineered surface. Therefore, friction reduction is considered to be necessary for improved efficiency of machines. This study investigated the effect of friction property fur angles of micro-scale crosshatch grooved surface pattern on bearing steel flat mated with pin-on-disk. We obtain sample which can be fabricated by photolithography process. We discuss friction property depend on an angle of cross-hatch grooved pattern. We can verify the lubrication mechanism as a Stribeck curve, which has a relationship between the friction coefficient and a dimensionless parameter under the lubrication condition. It was found that the friction coefficient was related to angle of crosshatch on surface, even when surface pattern was the same density.