• 한국지진공학회논문집
• /
• 제21권4호
• /
• pp.153-161
• /
• 2017

Liquid storage tank is one of the major infrastructures and generally used to store gases, drinking and utilizing water, dangerous fluids, fire water and so on. According to the recent reports and experiences, the tank structures are damaged in many earthquakes due to their low energy dissipating capacity. Therefore, many researchers have been tried to know the dynamic properties of the tanks including liquids. However, vary limited experimental studies are carried out using relatively small tank models. In this study, a series of shaking table tests are performed with maximum 2 m cubic rectangular liquid storage tanks made of steel to measure the natural frequency and estimate damping coefficient of impulsive and convective mode of the tanks. Especially, the damping values under different shapes and excitation methods are estimated by logarithmic decrement method and half power band-pass method and compared with current design code and standards such as ASCE 7, Eurocode 8 and NZS. Test results show that the impulsive mode damping is around 2% which is proposed by general standards and codes but the impulsive mode damping is 0.13% average that is slightly lower than the code recommendation.

• Fisheries and Aquatic Sciences
• /
• 제16권4호
• /
• pp.279-283
• /
• 2013

We tested the effects of various distillers dried grains (DDGs) in a formulated diet on growth and body composition of juvenile sea cucumber Apostichopus japonicus. DDG is a solid residue obtained by filtering an aqueous mixture of fermented rice with Aspergillus oryzae and yeasts. Six isonitrogenous and isocaloric diets (DDG0, DDG-G, DDG-C, DDG-K, DDG-W, and DDG-P) were formulated to contain 20% DDG obtained from different Makgeolli factories. Juvenile sea cucumber (average weight, $2.1{\pm}0.02$ g) were randomly distributed in eighteen 50-L rectangular plastic tanks (40 L of water each) in a seawater flow-through system at a density of 50 juveniles/tank. Three replicate groups of sea cucumber were fed each of the six experimental diets at a feeding rate of 5% body weight per day for 22 weeks. At the end of the feeding experiment, survival and weight gain of the juvenile sea cucumber were not affected by the type of dietary DDG (P > 0.05), and the proximate and amino acid compositions of the whole body were not affected by dietary DDG diets (P > 0.05). These results indicate that rice-based DDG is a potential dietary ingredient that could be used at dietary concentrations of up to 20% for growth of juvenile sea cucumber.

• Advances in concrete construction
• /
• 제13권3호
• /
• pp.243-254
• /
• 2022

Reinforced concrete (RC) deep beams are critical structural elements used in offshore pile caps, rectangular cross-section water tanks, silo structures, transfer beams in high-rise buildings, and bent caps. As a result of the low shear span ratio to effective depth (a/d) in deep beams, arch action occurs, which leads to shear failure. Several studies have been carried out to improve the shear resistance of RC deep beams and avoid brittle fracture behavior in recent years. This study was performed to investigate the behavior of RC deep beams numerically and experimentally with different reinforcement arrangements. Deep beams with four different reinforcement arrangements were produced and tested under monotonic static loading in the study's scope. The horizontal and vertical shear reinforcement members were changed in the test specimens to obtain the effects of different reinforcement arrangements. However, the rebars used for tension and the vertical shear reinforcement ratio were constant. In addition, the behavior of each deep beam was obtained numerically with commercial finite element analysis (FEA) software ABAQUS, and the findings were compared with the experimental results. The results showed that the reinforcements placed diagonally significantly increased the load-carrying and energy absorption capacities of RC deep beams. Moreover, an apparent plastic plateau was seen in the load-displacement curves of these test specimens in question (DE-2 and DE-3). This finding also indicated that diagonally located reinforcements improve displacement ductility. Also, the numerical results showed that the FEM method could be used to accurately predict RC deep beams'behavior with different reinforcement arrangements.

• 대한조선학회논문집
• /
• 제35권4호
• /
• pp.27-37
• /
• 1998

선박이 대형화되고, LNG선의 건조가 활발해지면서 액체화물탱크의 내부유동을 뜻하는 슬로싱에 대한 연구가 중요해지고 있다. 슬로싱에 의한 충격압력의 크기와 특성을 파악하기 위하여 직사각형 모델에 대한 체계적인 실험을 수행하여 회전각, 동요주파수, 적재수심에 따른 내부유동의 특성을 분석하였고, 충격압력이 가해지는 탱크벽면의 구조응답을 계측하여 유탄성효과를 고찰하였다. 탱크의 내부유동은 고차경계요소법을 이용하여 해석하였고, 평판의 진동에 의해 유기되는 유체력은 고유함수 전개법을 이용하여 부가질량과 감쇠력으로 표현하였다. 충격하중이 작용하는 경우 유탄성 효과를 고려한 탱크 벽면은 부가질량의 영향으로 그 때의 수심에 해당하는 접수진동수로 진동하였고, 벽면에서 압력은 유탄성효과를 고려하지 않은 경우에 비해 두 배 이상 크게 나타났다. 이를 실험과 계산에서 모두 확인하였고, 충격하중에 의한 평판의 거동에서 유탄성효과를 규명하였다

• 한국수산과학회지
• /
• 제42권6호
• /
• pp.621-627
• /
• 2009

In order to standardize the juvenile abalone rearing technique, we selected sample farms by region in East, West and South coasts of Korea and Jeju island. We also have reviewed previous literature and visited farms to survey on the management of abalone juvenile production, spawning, hatching and so forth. Results of investigation are as follows: The light colors of tanks for larvae breeding are good for a frequent examination of larvae behaviour changes during the breeding period. The tank for the abalone juvenile production is a rectangular form in general and its size should amount to 3.5 m in length and 1.2 m width. It also should be built with proper drainage. The best age and size of adult for juvenile production are 3-6 years old individuals, with 9-12 cm separate burial and 125-150 g average weight. To induce spawning, the use of the exposure on air and ultraviolet ray together was the most effective. The density of larvae by plate should be 150-300 individuals and the proper stocking density was est imated and amount to 10-30 individuals. It has been shown that a correlation between water surface size($X_1$) and number of plates ($Y_1$), when producing abalone juveniles, is quite high and it is described by equation $Y_1=138.88X_1-5,736.8\;(R^2=0.9028)$. In addition, it has also been shown that a correlation between production of abalone juveniles ($Y_2$) and number of plates ($X_2$) is high and it is described by equation $Y_2=4.554X_2+12,493\;(R^2=0.8818)$. In Jindo region where a mass production of juveniles abalone has been done, it was shown, that a correlation between rearing water surface size ($X_3$) and production of juveniles abalone ($Y_3$) is very high and this relationship was described by the equation $Y_3=747.03X_2+94,359(R^2=0.9809)$. It has also been shown that a correlation between water surface size ($X_4$) and production of abalone juveniles ($Y_4$) in nationwide is high and the relationship between this variables was described by equation $Y_4=635.85X_4+99,923\;(R^2=0.9020)$.