• Progress in Superconductivity and Cryogenics
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• v.24 no.4
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• pp.59-64
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• 2022

The cryogenic system of RAON which is Korea's first heavy ion accelerator was numerically modeled and simulated. EcosimPro which is widely used off-the-shelf numerical software for a large scale cryogenic system was used for the simulation. The model of SRF TF cryogenic system, which is the testbed of cryomodule, was firstly established. The integrity of system of SRF TF was confirmed by comparison of simulation and experimental results. The cool-down strategy to minimize the thermal stress of the cavity was simulated and an optimal strategy was established. In addition, the influence of valve and pump control parameters on the cooling time was investigated, and optimal control parameters were also derived. The cryogenic system of SCL3 that is a low-energy acceleration section including 55 cryomodules, valve boxes, and helium supply lines was also modeled. The soundness of the thermal shield system and interlock system of SCL3 was investigated.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.15-18
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• 2006

The test result of mat concrete applying both hydration heat difference and insulation curing method on new construction of Cheongju university educational building are summarized as following. Both fresh concrete and compressive strength properties were satisfied In aimed value. Setting time of concrete incorporating 15% of fly ash(FA) retarded 1.2 hour than control concrete. Temperature history of mali concrete indicated that the highest temperature of center was exhibited at $126^{\circ}C$ after 51 hours while the highest temperature of upper section was $10.6^{\circ}C$ after 46 hours. Temperature Difference between center and surface was managed at less than $6^{\circ}C$ during whole curing period. In addition the temperature of upper section secured more than $3.3^{\circ}C$ while the temperature of outside was indicated at less than $-10^{\circ}C$. Maturity by parts of construction secured more than $30^{\circ}C$ DD higher than outside at 3 days. The more number of times, applying insulation curing method by double bubble sheets, increased, the higher economic effect was secured. Overall it was clear that applying both double bubble sheets and hydration heat difference method on this new construction can resist hydration heat crack, early frost demage and strength decrease. It also significantly contributed quality improvement of cold weather concreting

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.485-490
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• 2007

The purpose in having a control rod on a buoy system is to control the motion of it. The system may be composed entirely of a single circular cylinder and a long mooring anchor cable. A control rod has one function to perform in meeting its purpose, and that is to develop a control force in consequence of its orientation and movement relative to the water. The forces and moments generated as a result of the effects of mutual interference. then determine the stability characteristics of the body. In this paper, the study of control-rod-attached buoy's 2-dimensional section was accomplished. model tests and numerical simulations had been carried out with different diameters of control rods. and varying the Reynolds number $Re=5,000{\sim}25,000$ based on the cylinder diameter(D=50mm) to predict the performance of the body and the 2 frame particle tracking method Iud been used to obtain the velocity distribution in the flow field. 50mm circular cylinder Iud been used during the whole experiments and measured results had been compared with each other.

• Computers and Concrete
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• v.1 no.3
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• pp.355-369
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• 2004

This paper presents a study of four finite element techniques that can be used to model slabon-beam highway bridges. The feasibility and correctness of each modeling technique are examined by applying them to a prestressed concrete I-beam bridge and a prestressed concrete box-beam bridge. Other issues related to bridge modeling such as torsional constant, support conditions, and quality control check are studied in detail and discussed in the paper. It is found that, under truck loading, the bending stress distribution in a beam section depends on the modeling technique being utilized. It is observed that the behavior of the bridge superstructure can be better represented when accounting for composite behavior between the supporting beams and slab.

• Steel and Composite Structures
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• v.21 no.3
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• pp.661-677
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• 2016

The quasi static test of the steel reinforced concrete (SRC) bridge piers and rigid frame arch bridge structure with SRC piers was conducted in the laboratory, and the seismic performance of SRC piers was compared with that of reinforced concrete (RC) bridge piers. In the test, the failure process, the failure mechanism, hysteretic curves, skeleton curves, ductility coefficient, stiffness degradation curves and the energy dissipation curves were analyzed. According to the $M-{\Phi}$ relationship of fiber section, the three-wire type theoretical skeleton curve of the lateral force and the pier top displacement was proposed, and the theoretical skeleton curves are well consistent with the experimental curves. Based on the theoretical model, the effects of the concrete strength, axial compression ratio, slenderness ratio, reinforcement ratio, and the stiffness ratio of arch to pier on the skeleton curve were analyzed.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.3
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• pp.407-417
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• 2015

Recently, piezo-aeroelastic energy harvesting has received greater attention. In the present study, a piezo-aeroelastic energy harvester using a nonlinear trailing-edge flap is proposed, and its nonlinear aeroelastic behaviors are investigated. The energy harvester is modeled using a piezo-aeroelastic model of a two-dimensional typical section airfoil with a trailing-edge flap (TEF). A piezo-aeroelastic analysis is carried out using RL and time-integration methods, and the results are verified with the experimental data. The linearizing method using a describing function is used for the frequency domain analysis of the nonlinear piezo-aeroelastic system. From the linear and nonlinear piezo-aeroelastic analysis, the limit cycle oscillation (LCO) characteristics of the proposed energy harvester with the nonlinear TEF are investigated in both the frequency and time domains. Finally, the authors discuss the air speed range for effective piezo-aeroelastic energy harvesting.

• 한국전산유체공학회:학술대회논문집
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• 2002.05a
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• pp.94-101
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• 2002

The steam turbine rotor blade is designed using the Turbine Rotor Design Package developed by the authors. It can quickly accomplish blade shape design in the power plant industry. The quasi-3d code is employed for analysis of passage flow in the blade sections. Iterative change of each blade shape is made by moving position of control points in the Bezier curve under GUI(graphic user interface) environment. The full 3-D blade shape is obtained by stacking of the section blades.

• Toxicological Research
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• v.9 no.1
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• pp.83-98
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• 1993

LBD-007, a newly developed recombinant human interferon alpha A, was at dose levels of 0, 3 $\times$ $10^6$, 6 $\times$ $10^6$ and 12 $\times$ $10^6$ IU/kg/day administered subctaneously to pregnant Sprague-Dawley rats during the organogenetic period. Ethylenethiourea was used as a positive control. 2/3 of dams per group were subjected to caesarean section on day 20 of pregnancy and the remaining 10 dams per group were allowed to deliver. Effects of test substance on dams, embryonal development development of F1 fetuses, as well as growth, behaviour and mating performance of F1 offspring were examined. 1. No treatment-related changes in clinical signs, food consumption, body weight and necropsy findings of dams were observed.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.115-121
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• 1996

Recently, the Z-Map model has been used widely to represent the three dimensional geometric shape and to achieve the cross-section and point evaluation of the shape. In this paper, the CNC cutting planning and simulation modules for product with three dimensional geometric shape are realized based on the Z-Map model. The realized system has the various capabilities related to the automatic generation of tool path for the rough and finish cutting processes, the automatic elimination of overcut, the automatic generation of CNC program for a machining center and the cutting simulation. Especially, the overcut-free tool path is obtained by using the CL Z-Map models which are composed of the offset surfaces of the geometric shape of product.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.694-701
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• 2018

Larger crack widths can be observed more in FRP-reinforced concrete members than in steel-reinforced concrete members as a result of the lower elastic modulus and bond strength of FRP reinforcement. The ACI 440.1R-15 design guide provides equations derived as the maximum bar spacing to control the crack widths indirectly. On the other hand, it is not concerned with long-term effects on the crack control design provisions. This study provides suggestions for how to incorporate time-dependent effects into the crack width equation. The work presented herein includes the results from 8 beams composed of four rectangular and T-shaped FRP-reinforced concrete beams tested for one year under four-point bending. Over a one year period, the crack widths increased as much as 2.6~3.0 times in GFRP and AFRP-reinforced specimens and 1.1~1.4 times in the CFRP-reinforced specimens compared to steel-reinforced specimens. In addition, the average multiple for crack width at one year relative to the instantaneous crack width upon the application of the sustained load was 2.4 in the specimens with a rectangular section and 3.1 in the specimens with a T-shaped section. As a result, it is recommended conservatively that the time-dependent coefficient be taken as 2.5 for the rectangular beams and 3.5 for T-beams.