• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11a
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• pp.339-347
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• 2005

A type IP-2 transport package should prevent a loss or dispersal of the radioactive contents and a more than $20\%$ increase in the maximum radiation level at any external surface of the package when it were subjected to the drop test under the normal conditions of transport. If a shielding thickness of IP-2 transport package is thick, a bolted lid type may prevent a loss or dispersal of the radioactive contents than the door type of ISO containers which are generally used as a type IP-2 transport package. In this paper, to evaluate the effect of drop directions on the bolt tension and the coherence of a bolt, the drop tests of preliminary small model are tested and evaluated for seven directions before the drop test of a type IP-2 transport package with a bolted lid type under the normal conditions of transport. Seven drop directions which are a bottom-vertical drop, a lid-vortical drop. a horizontal drop and four corner drops have been carried out. Using a force sensor, the bolt tension during the drop impact is measured. The coherence of bolt is evaluated by the difference between the fastening torque of bolt before a drop test and the unfastening torque of bolt after a drop impact.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.3
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• pp.457-469
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• 1997

A nuclear spent fuel shipping cask is required by IAEA and domestic regulations to withstand a 9m free drop condition. In this paper, the structural analysis under the 9m side drop condition was performed to understand the dynamic impact behavior and to evaluate the safety of the cask for 7 PWR nuclear spent fuel assemblies. The analysis result was compared with the measured value of the 9m side drop test for the 1/3 scaled-down model and the accuracy of the 3D analysis was confirmed. Analysis in accordance with the diameter of impact limiters for the proto-type cask were performed. Through the analysis, the impact behaviors due to the side drop and the effects dependent on the diameter of impact limiters were grasped. Maximum stress intensities on each part of the cask were respectively calculated by using the stress evaluation program and the structural safety of the cask was finally evaluated in accordance with the regulations.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.3
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• pp.245-254
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• 2005

Radioactive material is used in the various fields. The numbers of transport for radioactive material have been gradually increased in both domestic and International regions. The safety of the cask should be secured to safely transport of radioactive material. The korean atomic law and the IAEA safety standards prescribe regulations lot the safe transport of radioactive material The cask for spent fuel is comprised of the body and the impact limiter. In this study, the empirical equation of the cask impact force is proposed based on the dimensional analysis. Using this empirical equation the characteristics of the impact limiter are analyzed. The results are also validated by comparing with the previous results of the impact area method and the finite element analysis. The present method can be used to predict the impact force of the cask.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.5
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• pp.472-481
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• 2008

In this study hydraulic experiment was carried out to investigate the flow characteristics in the submerged outlet structure of Boryeong power plant and the efficiency of bubble reduction by installing horizontal porous plate in the outlet structure. The cross-sectional mean velocity in the submerged outlet structure was smaller than 1 m/s, the target value at the design stage to prevent bubble outflow to the open sea area. In addition, it was found that the maximum depth of bubble penetration is reduced 30 to 50% by installing the horizontal porous plate at the second falling location in the submerged outlet structure. It is expected that the total bubble amount entrained in the water will be most efficiently reduced by installing square-hole-shape porous plate of 20 cm hole size and making its central section as non-porous structure to dissipate the energy of falling water.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.539-543
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• 2008

이 연구에서는 보령화력발전소 방수로 수중방류구조에 대한 수리모형실험을 수행하여 수중방류구조 내 흐름 양상을 고찰하고, 수평 유공판의 거품저감 효과를 검토하였다. 수중방류구조 내 유속은 설계시 거품의 부상 및 외해 유출 방지를 위해 고려한 목표값 1 m/s 이내에 분포하였다. 또한, 2차 낙하 위치에 수평 유공판을 설치함에 따라 거품 발생량이 크게 감소함을 확인하였다. 그러나, 수평 유공판 설치에 따라서 평균유속은 거의 변화가 없었으며, 다만 외해 조위가 운전정지수위에 해당할 경우에는 수평 유공판 아래에서 연직방향 흐름의 세기가 감소하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.7
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• pp.495-505
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• 2009

A two-dimensional circular cylinder freely falling in a channel has been simulated by using immersed boundary - lattice Boltzmann method (IB-LBM) in order to analyze the characteristics of motion originated by the interaction between the fluid flow and the cylinder. The wide range of the solid/fluid density ratio has been considered to identify the effect of the solid/fluid density ratio on the motion characteristics such as the falling time, the transverse force and the trajectory in the streamwise and transverse directions. In addition, the effect of the gap between the cylinder and the wall on the motion of a two-dimensional freely falling circular cylinder has been revealed by taking into account a various range of the gap size. As the cylinder is close to the wall at the initial dropping position, vortex shedding in the wake occurs early since the shear flow formed in the spacing between the cylinder and the wall drives flow instabilities from the initial stage of freely falling. In order to consider the characteristics of transverse motion of the cylinder in the initial stage of freely falling, quantitative information about the cylinder motion variables such as the transverse force, trajectory and settling time has been investigate.

• Magazine of the Korean Society of Agricultural Engineers
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• v.13 no.1
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• pp.2206-2217
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• 1971

Spillway and discharge channel of reservoirs require the Control of Large volume of water under high pressure. The energies at the downstream end of spillway or discharge channel are tremendous. Therefore, Some means of expending the energy of the high-velocity flow is required to prevent scour of the riverbed, minimize erosion, and prevent undermining structures or dam it self. This may be accomplished by Constructing an energy dissipator at the downstream end of spillway or discharge channel disigned to dissipated the excessive energy and establish safe flow Condition in the outlet channel. There are many types of energy dissipators, stilling basins are the most familar energy dissipator. In the stilling basin, most energies are dissipated by hydraulic jump. stilling basins have some length to cover hydraulic jump length. So stilling basins require much concrete works and high construction cost. Flip bucket type energy dissipators require less construction cost. If the streambed is composed of firm rock and it is certain that the scour will not progress upstream to the extent that the safety of the structure might be endangered, flip backet type energy dissipators are the most recommendable one. Following items are tested and studied with bucket radius, $R=7h_2$,(medium of $4h_2{\geqq}R{\geqq}10h_2$). 1. Allowable upstream channel slop of bucket. 2. Adequate bucket lip angle for good performance of flip bucket. Also followings are reviwed. 1. Scour by jet flow. 2. Negative pressure distribution and air movement below nappe flow. From the test and study, following results were obtained. 1. Upstream channel slope of bucket (S=H/L) should be 0.25<H/L<0.75 for good performance of flip bucket. 2. Adequated lip angle $30^{\circ}{\sim}40^{\circ}$ are more reliable than $20^{\circ}{\sim}30^{\circ}$ for the safety of structures.

• Journal of the Korean Society for Advanced Composite Structures
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• v.2 no.1
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• pp.1-7
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• 2011

In this study the optimal stacking section was selected by pendulum impact test for six different stacking sections of the composite safety barrier. The beam cross-section shape was determined through the poll on six different beam cross-section shapes. The six kinds of stacking design for the determined beam cross-section were suggested. CSM, DB, DBT and Roving fibers were used for stacking design. Horizontal beam and 3:1 sloped beam were modeled by using LS-DYNA. The fall impact simulation was carried out by using rectangular pendulum and cylinder pendulum. Optimal stacking section was determined by comparing and analyzing the impact simulation results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.3
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• pp.274-279
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• 2010

The present work is to analyze the longitudinal static stability and the drop trajectory of fighter aircraft's external fuel tank, of which horizontal fin is modified as the 20% scale down size compared with the original one. The analytical results to the pitching stability of external fuel tank using a thin airfoil's aerodynamic force data show the corresponding tendency to results of wind tunnel experiment. Results of trajectory simulation by the 6 degree of freedom equations of motion, comparing with drop trajectories of wind tunnel experiment, are shown that aircraft's attitude affects strongly on horizontal movement but not on the vertical movement. Those results give the reliability to aircraft safety when the external fuel tank with the 20% reduced horizontal fins is released from aircraft based on the flight manual.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.6
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• pp.947-958
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• 1986

물-증기 역류 성층이상유동에서의 평균 액체층 두께가 여러가지 경사각과 종횡비에 따라 측정되었다. 난류유동에 있어서 전단응력분포의 선형화와 von Karman의 혼합길이 이론을 근거로 평균 액체층의 두께에 대한 관계식이 제시되었으며 실험결과와 잘 일치하였음을 보였다. 접촉면에서의 조파저항이 고려되지 않은 해석결과는, 수평 성층유동의 경우에, 평균 액체층 두께보다는 오히려 파곡까지의 액체층 두께를 예측하고 있는 것으로 나타났다. 또한 평균 액체층 두께에 대한 실험 상관관계식이 계산시 편의를 위해 쉽게 인지할 수 있는 매개변수들의 항들롤 제시되었다.