• 제목/요약/키워드: Negative added mass

검색결과 20건 처리시간 0.021초

감쇠판이 부착된 원기둥의 동유체력 특성 (Hydrodynamic Forces Characteristics of a Circular Cylinder with a Damping Plate)

  • 조일형
    • 한국해양공학회지
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    • 제25권1호
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    • pp.1-7
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    • 2011
  • The radiation of water waves by a heaving truncated circular cylinder with damping plate is solved in the frame of the three-dimensional linear potential theory. The damping plate has a distinct advantage in reducing the motion response of a floating circular cylinder by increasing the added mass and the damping coefficient. Using the matched eigenfunction expansion method, the characteristics of hydrodynamic added mass and the damping coefficient are investigated with various system parameters, such as the radius and submergence depth of the damping plate. It is found that both added mass and the damping coefficient are significantly increased due to the arranged features of the larger damping plate with shallow submergence, which are positive factors as a motion reduction device of the floating offshore platform. Also the numerical results for an oscillating submerged disk show that the added mass is negative and that the damping coefficient has a peak value at resonant frequency when submergence depth is sufficiently small.

투과성 내부재가 설치된 사각형 탱크내의 슬로싱 해석 (Sloshing Analysis in Rectangular Tank with Porous Baffle)

  • 조일형
    • 한국해양공학회지
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    • 제29권1호
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    • pp.1-8
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    • 2015
  • An analytical model of liquid sloshing is developed to consider the energy-loss effect through a partially submerged porous baffle in a horizontally oscillating rectangular tank. The nonlinear boundary condition at the porous baffle is derived to accurately capture both the added inertia effects and the energy-loss effects from an equivalent non-linear drag law. Using the eigenfunction expansion method, the horizontal hydrodynamic force (added mass, damping coefficient) on both the wall and baffle induced by the fluid motion is assessed for various combinations of porosity, submergence depth, and the tank's motion amplitude. It is found that a negative value for the added mass and a sharp peak in the damping curve occur near the resonant frequencies. In particular, the hydrodynamic force and free surface amplitude can be largely reduced by installing the proper porous baffle in a tank. The optimal porosity of a porous baffle is near P=0.1.

Second Order Effect Induced by a Forced Heaving

  • Kim, Won-Joong;Kwon, Sun-Hong
    • Journal of Advanced Research in Ocean Engineering
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    • 제2권1호
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    • pp.12-21
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    • 2016
  • In this paper, the $2^{nd}$ order hydrodynamic force effect of heaving submerged circular cylinder is considered, with the linear potential theory. Boundary value problem (BVP) is expanded up to the $2^{nd}$ order by using of the perturbation method and the $2^{nd}$ order velocity potential is calculated by means of integral equation technique using the classical Green's function expressed in cylindrical coordinates. The method of solving BVP is based on eigenfunction expansions. With different cylinder heights and heaving frequencies, graphical results are presented. As a result of the study, the cause of oscillatory force pattern is analyzed with the occurrence of negative added mass when a top of the cylinder gets closer to the free surface.

Determination of Niflumic Acid in Human Urine by Gas Chromatography/Negative Chemical lonization Mass Spectrometry

  • Myung, Seung-Woon;Kim, Myung-Soo;Cho, Hyun-Woo;Park, Jong-Sei
    • Archives of Pharmacal Research
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    • 제19권6호
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    • pp.566-569
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    • 1996
  • A sensitivity method has been developed for the detection and determination of niflmic acid(NA) in human urine. Samples were extracted with diethylether. Flunixin (FN) was added to the sample prior to extraction as an internal standard. Niflumic acid was converted to its methyl derivative and analyzed by capillary gas chromatography/negative chemical isonization mass spectrometry. Using selected ion monitoring (SIM), the levels of NA down to 5 pg/ml could be detected in 5 ml spiked urine sample. Calibration curve was linear over the range of 0.5 ppm-50 ppm. The recovery of niflumic acid from urine at 40 pg/ml was to be $91.7{\pm}3.8(n=3)$ and the coefficient of variation was 4.1%.

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닭 전염성 기관지염에 관한 연구: II. 간접 enzyme-linked immunosorbent assay(ELISA)에 의한 항체가 측정 (Studies on avian infectious bronchitis: II. Standardization of an indirect enzyme-linked immunosorbent assay (ELISA) for antibody measurement)

  • 장정호;김선중
    • 대한수의학회지
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    • 제29권4호
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    • pp.503-515
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    • 1989
  • Critical parameters affecting sensitivity and specificity of an enzyme-linked immunosorbent assay(ELISA) for detection of antibodies to avian infections bronchitis virus(IBV) were standardized. By adopting the optimized conditions an equation calculating ELISA antibody titers from the observations at single serum dilution was formulated. The purified antigen of IBV Mass-41 strain was dispensed into polystyrene microplate wells at a concentration of 300ng per well($100{\mu}l$) and the plates were coated by completey drying at $37^{\circ}C$. Diluted chicken serum and horseradish peroxidase conjugated goat anti-chicken IgG were added in order in $100{\mu}l$ volumes per well and allowed to react for 30 minutes each at room temperature. Just before use and after each reaction the plates were washed three times with distilled water. Finally o-phenylenediamine solution was added as an enzyme substrate. After incubation for another 15 minutes at room temperature absorbances were read at 492nm. Hyperimmune serum against Mass-41 strain was used as internal reference positive(IRP) serum. After repeated titration of IRP and negative serum, a constant titer of IRP was determined. Serum titrations were carried out for various sample sera together with IRP and negative sera and the observed titers of sample sera were corrected by reflecting the ratio between observed and constant titers of IRP serum. These corrected titers of the sample sera were plotted against sample/positive(S/P) OD ratios. All the OD's measured in the serum titrations were also corrected by substracting negative serum OD. The following equation was formulated from the above data; $Log_{10}$ ELISA titer=$5.568({\log}_{10}S/P)+4.161$ Thus it was possible to calculate ELISA titer by measuring absorbance at 1/400 single serum dilution. Titer measured by cross ELISA tests employing Mass-41 strain and three local IBV isolates were similar. These results suggest that the ELISA tests standardized in this study can be used for evaluating not only vaccinal immunity but also for infection status against fields IBV's.

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한국의 대중문화에 Animation Character가 미치는 부정적인 영향 (A Negative Effect of Animation Character in Mass Culture of Korea)

  • 김홍산;신정숙
    • 디자인학연구
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    • 제14권2호
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    • pp.147-154
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    • 2001
  • 애니메이션 캐릭터는 아이디어 지향의 고 부가가치 산업으로 다양한 시너지 효과를 창출하기 때문에 경제적인 측면만으로도 그 가치가 높다. 무엇보다도 애니메이션 캐릭터의 가치는 대중문화 커뮤니케이터로서의 역할에 있다. 애니메이션 캐릭터의 범람속에서 생활하는 대중들은 캐릭터에 의해 표현되는 다양한 성격과 행동에 영향받고 있다. 그러나 범람이라고 할만큼 대중의 생활을 둘러싸고 있는 애니메이션 캐릭터들의 성격과 행동들은 주로 극단적인 성향을 나타내고 있어, 대중사회의 유지와 존속에 필요한 역할모델의 제시에 부정적인 기능을 하고 있다.

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Rapid Detection of Ovarian Cancer from Immunized Serum Using a Quartz Crystal Microbalance Immunosensor

  • Chen, Yan;Huang, Xian-He;Shi, Hua-Shan;Mu, Bo;Lv, Qun
    • Asian Pacific Journal of Cancer Prevention
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    • 제13권7호
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    • pp.3423-3426
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    • 2012
  • Background: The objective of this study was to measure the antibody content of NuTu-19 ovarian cancer cells in serum samples using a quartz crystal microbalance (QCM) immunosensor. Materials and Methods: NuTu-19 cells were first cultured onto the electrode surfaces of crystals in Dulbecco's modified Eagle medium, and then specified amounts of immunized serum samples of immunized rabbit were also added. The change in mass caused by specific adsorbtion of antibodies of NuTu-19 to the surfaces of the crystals was detected. Results: The change in resonance frequency of crystals caused by immobilization of NuTu-19 cells was from 83 to 429Hz. The antibody content of NuTu-19 detected was 341ng/ul. The frequency shifts were linearly dependent on the amount of antibody mass in the range of 69 to 340ng. The positive detection rate and the negative detection rate were 80% and 100%, respectively. Conclusion: This immunoassay provides a viable alternative to other early ovarian cancer detection methods and is particularly suited for health screening of the general population.

Wave Response and Ship Motion in a Harbor Excited by Long Waves

  • Cho, Il-Hyoung;Choi, Hang-S.
    • Selected Papers of The Society of Naval Architects of Korea
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    • 제2권1호
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    • pp.47-62
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    • 1994
  • Herein the surge-heave-pitch motion of a ship in harbor has been analyzed within the framework of linear potential theory. The ship is assumed to be slender and moored at an arbitrary position in a rectangular harbor with a constant depth. The coast line is assumed to be straight. The ship and harbor responses to incident long waves are represented in terms of Green's function, which is the solution of tole Helmholtz equation satisfying necessary boundary conditions. An integral equation is obtained from matching condition between harbor and ocean solutions, and it is replaced by an equivalent variational form. Numerical results sallow that the ship motion can be highly amplified at the frequencies, where the harbor is resonated by the incident wave. At the resonant frequencies, the added mass for vertical motions becomes negative and the damping forte changes abruptly.

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제한수역에서의 동유체력에 대한 고찰 (On the Characteristics of Hydrodynamic Forces in a Restricted Water)

  • 조일형;최항순
    • 대한조선학회논문집
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    • 제29권1호
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    • pp.55-60
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    • 1992
  • 본 논문에서는 선형포턴셜이론을 이용하여 제한수로에 놓인 2차원 주상체에 작용하는 동유체력과 운동응답의 특성을 고찰하였다. 유체영역을, 수로입구영역 그리고 수로영역으로 구분하여 우선 각 영역에서 해를 독립적으로 구한 다음 이를 인접영역의 해와 정합시켜 완전해를 구하였다. 수로의 길이보다 대략 4배가 긴 파장의 입사파는 수로내 유동을 공진시킨다. 이때 주상체에 작용하는 부가질량은 음의 값을 갖게 되며 동유체감쇠력은 급격한 변화를 보이고 주상체의 수평운동은 최대가 됨을 밝혔다.

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Effect of superdosing phytase on productive performance and egg quality in laying hens

  • Kim, Jong Hyuk;Pitargue, Franco Martinez;Jung, Hyunjung;Han, Gi Ppeum;Choi, Hyeon Seok;Kil, Dong Yong
    • Asian-Australasian Journal of Animal Sciences
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    • 제30권7호
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    • pp.994-998
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    • 2017
  • Objective: An experiment was conducted to determine the effect of superdosing phytase on productive performance and egg quality in laying hens. Methods: A total of 200 42-wk-old Hy-Line Brown laying hens were allotted into 1 of 5 dietary treatments with 5 replicates consisting of 8 hens per replicate. The positive control (PC) and negative control diets (NC) were prepared based on the recommended P levels in layer diets. Supplemental phytase was added to the negative control diet at 10,000 (SD10), 20,000 (SD20), or 30,000 (SD30) fytase units (FTU)/kg. Productive performance was summarized for 6 weeks from 42 weeks to 47 weeks of age. Egg quality was assessed from 4 eggs per replicate randomly collected at the conclusion of the experiment. Results: The SD20 treatment had greater (p<0.05) hen-day egg production than PC, NC, and SD10 treatment groups. There was no difference in hen-day egg production between SD20 and SD30 treatment groups. However, SD30 treatment had greater (p<0.05) hen-day egg production than PC treatment, but showed no difference in hen-day egg production as compared to NC and SD10 treatment groups. However, egg weight, egg mass, feed intake, and feed conversion ratio were not affected by dietary treatments. Egg quality including eggshell strength, eggshell color, egg yolk color, and haugh unit was not influenced by dietary treatments. Conclusion: Superdosing level of 20,000 FTU/kg phytase in diets has a positive effect on egg production rate, but no beneficial effect on egg quality in laying hens.