• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.159-164
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• 2010

We experiment to analyze on current limiting and recovery characteristics of trigger type SFCL as the composition of the contact. Generally, some superconductor of SFCL is relatively largely loaded due to limit the fault current by oneself and recovery time is affected until the fault cleared. However, in the fault, the proposal trigger type SFCL transfer the fault current to current limiting reactor(CLR) using power switch so it could reduce the recovery time and load of the superconductor. However, because of applying the additional power switches, that could generate some power loss. Therefore, to solve this problem, we proposed the composition method of the double contact for a trigger type SFCL and analyzed on current limiting and recovery characteristics for ones.

• Structural Engineering and Mechanics
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• v.74 no.1
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• pp.69-82
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• 2020

A significant defect of space structures is the progressive collapse issue which may restrict their applicability. Force limiting devices (FLDs) have been designed to overcome this deficiency, though they don't operate efficiently in controlling the force displacement characteristics. To overcome this flaw, a new type of FLD is introduced in the present study. The "all steel accordion force limiting device" (AFLD) which consists of three main parts including cylindrical accordion solid core, tubular encasing and joint system is constructed and its behavior has been studied experimentally. To improve AFLD's behavior, Finite element analysis has been carried out by developing models in ABAQUS software. A comprehensive parametric study is done by considering the effective design parameters such as core material, accordion wave length and accordion inner diameter. From the results, it is found that AFLD can obtain a perfect control on the force-displacement characteristics as well as attaining the elastic-perfect plastic behavior. Obtaining higher levels of ultimate load carrying capacity, dissipated energy and ductility ratio can be encountered as the main privileges of this device. Ease of construction and erection are found to be further advantages of AFLD. Based on the obtained results, a procedure for predicting AFLD's behavior is offered.

• Journal of Biosystems Engineering
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• v.2 no.1
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• pp.33-48
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• 1977

Transporting agricultural products and the other material by the two-wheel-tractor (power-tiler)and trailer system may be one of its most widely used farming functions.The safety and hitching load for all the previaling performing conditions may be the general concern over the operation of the tiller-trailer system. In this study, a mathematical model to determine the static and dynamic forces excerting on the hitch point were developed . Based on the analysis of the model and the field measurements. the limiting hitching load and critical slope were analyzed. The results of the study are summarized as follows ; 1) The limit angle of slope land for the safety steering that two-wheel tractor-single axle trailer system was able to transport agricultural products was the direct angle (${\gamma}$) = 8 ; the cross angle$\beta$) 15 ; and it was decreased in accordance with the increase of carrying load ($W_4). 2) The critical velocity for safe operation in case of running on downward hill road was about 1.08m/sec. 3) The limiting carrying load for the safe steering was W$_4$=600kg. The degree of the safe steering for different braking methods was given in order as follows ; Simulataneous braking the tractor and trailer , braking the trailer only, and braking tractor only. 4) Among the three components of impact loads excerting on the hitch point, the component in the lateral direction ($P_{Vy}$) was near zero in spite of increase of hitching load ($W_4) , while the components in the other two mutually perpedicular directions ($P_{Vx}$ and ($P_{Vz}$) ) had larger values in horizontal plane than those in the slope lands. 5) Moment of forces on the lateral direction (M$y$) had the largest value among the three components of impact moment acting on the hitch point, however all the components were sharply increased in accordance with the increase of hitching loads ($W_4. Three components of the moment were the negative values.

• Geotechnical Engineering
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• v.13 no.6
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• pp.61-70
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• 1997

Although the load -settlement curve characteristics of embedded piles are different from those of driven piles, for the determination of their allowable loads the same analysis method has been adopted without any considerations. According to the related domestic chi teria, the analysis methods of load-settlement curve have some conflicts among themselves and have several vague points in obtaining the allowable capacity from ultimate or yield capacity. In order to solve those problems, the relevant literatures were reviewed. And also the result of 106 pile load tests was analysed. Analysis result indicates that analysis met hods of the load-settlement curve based on single mathematical curve are not suitable for the general analysis method of load-settlement curves due to their various characteristics. As a result, the appropriate analysis methods and safety factors for the determination of allowable capacity of pile are suggested in this paper.

• Journal of Auto-vehicle Safety Association
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• v.3 no.2
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• pp.5-10
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• 2011

Under the full frontal crash event, seatbelt system is the most typical and primary restraint device that prevents the second impact between an occupant and vehicle interior parts by limiting the forward motion of an occupant in the vehicle occupant packaging space. Today's restraint systems typically include the three-point seat belt with the pretensioner and the load limiter. A pretensioner preemptively tightens the seat belts removing any slack between a passenger and belt webbing which leads to early restraint of a passenger. After that a load limiter controls level of belt load by releasing the belt webbing to reduce occupant injurys. In this study, load characteristics of load limiters are optimized by the computer simulation with a MADYMO model for a frontal impact against the rigid wall at 56kph and then we suggest performance requirements. We derived optimum load characteristic from the results using four vehicle simulation models represented by the vehicle. Based on the results, we suggest the performance from the results of the second optimization using the simulation considering the design and the standardization. Finally, the performance requirements is verified by the sled tests including the load limiter device for the full vehicle condition.

• Journal of Korean Society of Steel Construction
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• v.12 no.3 s.46
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• pp.329-337
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• 2000

The Load and Resistance Factor Design(LRFD) Specification defines two sets of limiting width-to-thickness ratios. On the basis of these limiting values, steel sections are subdivided into three categories: compact, noncompact, and slender sections. In this paper, I-Type girders of a 2 span continuous steel bridge are divided into compact and non-compact sections and analyzed. In the design process, an optimization formulation was adopted and ADS, a Fortran program for Automated Design Synthesis, was used. In this study, we studied about change of the section between compact and non-compact using optimization formulation.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.242-246
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• 1999

For the fabrication of fault current limiting device using HTSC thick film, YBa$_2Cu_3O_x$ superconducting thick film was formed by surface diffusion process of the Y$_2BaCUO_5$ and the mixed compound of (3BaCuO$_2$+2CuO) expected to be liquid phase above the peritectic temperature of YBa$_2Cu_3O_x$. For the surface diffusion, the compounds of 3BaCuO$_2$+2CuO mixed with binder material was patterned on Y$_2BaCUO_5$ substrate by the screen printing method. After proper sintering, the characteristics of current limit on thick film fabricated was measured. The thick film was able to limit the current from 2.8213 mA$_{rms}$nu to 4.2034 mA$_{rms}$ with 500${\omega}$ load resistance, and from 4.1831 mA$_{rms}$ to 4.2150 mA$_{rms}$ with 10${\omega}$ load resistance.

• Transactions of Materials Processing
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• v.9 no.6
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• pp.670-680
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• 2000

The purpose of this study is to provide the database of forming limit diagram applicable to the warm forming of oil pan. The test materials are SCP1 and SCP3C with the thickness of 1.4mm which is used for the oil pan of automobile. The testing temperature is 5$^{\circ}C$~15$0^{\circ}C$ which is In the range of practical usage. The results are the forming limit diagram limiting dome height and the maximum punch load at each temperature such as 5$^{\circ}C$, $25^{\circ}C$, 6$0^{\circ}C$, 9$0^{\circ}C$, 12$0^{\circ}C$ and 15$0^{\circ}C$. From these results, we can see that the forming limit curves are translated depending upon the temperature and that FLC at low temperature is higher than at high temperature. Both of limiting dome height and maximum punch load also decrease as the temperature increases. Present results can be useful for die trial and forming analysis as a tool of evaluating the forming severity for the sheet metal forming processes at the warm working condition by comparing the practical strains with FLC.

• Journal of Korean Society of Steel Construction
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• v.25 no.3
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• pp.279-287
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• 2013

The steel members are applied to high rise building since they have high strength compare to the concrete member. On the other hand, the elastic buckling is likely to occur in steel member because of their small section. When the elastic buckling occur, the steel structure lose a load carrying capacity. The steel frame would be unstable due to a rapid decline in strength by buckling. The purpose of this study is the development of FLD(Force Limiting Device) to prevent a elastic buckling for a slender member. Further, the behavior of steel structures with FLD would be stable by high energy absorption capacity. The proposed type of FLD is the type of out-of-plane resistance. In this study, member test and FEM analysis for proposed type were performed. The test parameters are thickness and gradient angle of out-of-plane plate. The proposed type may be effective method for FLD.

• Journal of Korean Association for Spatial Structures
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• v.6 no.3 s.21
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• pp.87-92
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• 2006

This paper is a study on the experiment and elasto-plastic discrete limit analysis of reinforced concrete circular cylindrical shell by the rigid-bodies spring model. In the rigid bodies-spring model, each collapsed part or piece of structures at the limiting state of loading is assumed to behave like rigid bodies. The present author propose new discrete elements for elasto-plastic analysis of cylindrical shell structures, that is, a rectangular-shaped cylindrical element and a rhombus-shaped cylindrical element for the improvement and expansion of this rigid-bodies spring model. In this study, it is proposed how this rigid element-bodies spring model can be applied to the elasto-plastic discrete limit analysis of cylindrical shell structures. Some numerical results of elasto-plastic discrete limit analysis and experimental results such as the curve of load-displacement and the yielding and fracturing pattern of circular cylindrical shell under horizontal load are shown.