• Ocean Systems Engineering
• /
• v.10 no.2
• /
• pp.163-179
• /
• 2020

Considering the huge demand of several types of subsea equipment, as Christmas Trees, PLEMs (Pipeline End Manifolds), PLETs (Pipeline End Terminations) and manifolds for instance, a critical phase is its installation, especially when the equipment goes down through the water, crossing the splash zone. In this phase, the equipment is subject to slamming loads, which can induce impulsive loads in the installation wires and lead to their rupture. Slamming loads assessment formulation can be found in many references, like the Recommended Practice RP-N103 from DNV-GL (2011), a useful guide to evaluate installation loads. Regarding to the slamming loads, RP-N103 adopt some simplifying assumptions, as considering small dimensions for the equipment in relation to wave length, in order to estimate the slamming coefficient C_S used in load estimation. In this article, an experimental investigation based on typical subsea structure dimensions was performed to assess the slamming coefficient evaluation, considering a more specific scenario in terms of application, and some reduction of the slamming coefficient is achieved for higher velocities, with positive impact on operability.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.1209-1214
• /
• 2010

In these days, rail container service is being more important because it has relatively simple network. In addition, small lot sizes of shipment, frequent shipment, and demand for flexible service are important characteristics in rail container transportation. Efficient container operation at terminals is important in reducing transportation costs and load/unload time. This paper describes the assigning track of freight trains in the railway freight terminal. The paper addresses the operational requirements and facility restrictions to construct a mathematical model for track assignment. In addition, it suggests several types of objectives for the model.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.32 no.5
• /
• pp.469-483
• /
• 2012

The propagation characteristics of a mechanical wave in human soft tissue depend on its elastic properties. Investigation of these propagation characteristics is of paramount importance because it may enable us to diagnose cancer or tumor from the vibration response of the tissue. This paper investigates and compares displacement patterns generated in soft tissue due to several forms of low-frequency vibration sources placed on a surface. Among vibration sources considered are a normal load, tangential load, and antiplane shear load. We derive analytical expressions for displacements in viscoelastic single layers, and calculate displacement patterns in half space and infinite plate type tissue. Also, we simulate the vibration response of a finite-sized tissue using finite element method. The effects of the type of stress, the size and frequency of vibration sources, and medium boundaries on displacement patterns are discussed.

• Journal of Preventive Medicine and Public Health
• /
• v.24 no.4 s.36
• /
• pp.485-495
• /
• 1991

This study examined the effects of referral requirements for insurance patients which have been enforced since July 1, 1989 when medical insurance coverage was extended to the whole population except beneficiaries of medical assistance program. The requirements are mainly aimed at discouraging the use of tertiary care hospitals by imposing restrictions on the patient's choice of a medical service facility. The expectation is that such change in the pattern of medical care utilization would produce several desirable effects including increased efficiency in patient care and balanced development of various types of medical service facilities. In this study, these effects were assessed by the change in the number of out-patient visits and bed-days per illness episode and the share of each type of facility in the volume of services and the amount of expenditures after the implementation of the new referral system. The data for analysis were obtained from the claims to the insurance for government and school employees. The sample was drawn from the claims for the patients treated during the first six months of 1989, prior to the enforcement of referral requirements, and those of the patients treated during the first six months of 1990, after the enforcement. The 1989 sample included 299,824 claims (3.6% of total) and the 1990 sample included 332,131 (3.7% of total). The data were processed to make the unit of analysis an illness episode instead of an insurance claim. The facilities and types of care utilized for a given illness episode are defined to make up the pathway of medical care utilization. This pathway was conceived of as a Markov Chain process for further analysis. The conclusion emerged from the analysis is that the enforcement of referral requirements resulted in less use of tertiary care hospitals, and thereby decreased the volume of services and the amount of insurance expenses per illness episode. However, there are a few points that have to be taken into account in relation to the conclusion. The new referral system is likely to increase the use of medical services not covered by insurance, so that its impact on national health expenditures would be different from that on insurance expenditures. The extension of insurance coverage must have inereased patient load for all types of medical service organizations, and this increase may be partly responsible for producing the effects attributed to the new referral system. For example, excessive patient load for tertiary care hospitals may lead to the transfer of their patients to other types of facilities. Another point is that the data for this study correspond to very early phase of the new system. But both patients and medical care providers would adapt themselves to the new system to avoid or overcome its disadvantages for them, so as that its effects could change over time. Therefore, it is still necessary to closely monitor the impact of the referral requirements.

• Advances in aircraft and spacecraft science
• /
• v.11 no.1
• /
• pp.83-103
• /
• 2024

Adhesive bonding is currently widely used in many industrial fields, particularly in the aeronautics sector. Despite its advantages over mechanical joints such as riveting and welding, adhesive bonding is mostly used for secondary structures due to its low peel strength; especially if it is simultaneously exposed to temperature and humidity; and often presence of bonding defects. In fact, during joint preparation, several types of defects can be introduced into the adhesive layer such as air bubbles, cavities, or cracks, which induce stress concentrations potentially leading to premature failure. Indeed, the presence of defects in the adhesive joint has a significant effect on adhesive stresses, which emphasizes the need for a good surface treatment. The research in this field is aimed at minimizing the stresses in the adhesive joint at its free edges by geometric modifications of the ovelapping part and/or by changing the nature of the substrates. In this study, the finite element method is used to describe the mechanical behavior of bonded joints. Thus, a three-dimensional model is made to analyze the effect of defects in the adhesive joint at areas of high stress concentrations. The analysis consists of estimating the different stresses in an adhesive joint between two 2024-T3 aluminum plates. Two types of single lap joints(SLJ) were analyzed: a standard SLJ and another modified by removing 0.2 mm of material from the thickness of one plate along the overlap length, taking into account several factors such as the applied load, shape, size and position of the defect. The obtained results clearly show that the presence of a bonding defect significantly affects stresses in the adhesive joint, which become important if the joint is subjected to a higher applied load. On the other hand, the geometric modification made to the plate considerably reduces the various stresses in the adhesive joint even in the presence of a bonding defect.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.20 no.5
• /
• pp.285-293
• /
• 2016

Soil-foundation-structure interaction (SFSI) is one of the important issues in the seismic design for evaluating the exact behavior of the system. A seismic design of a structure can be more precise and economical, provided that the effect of SFSI is properly taken into account. In this study, a series of the dynamic centrifuge tests were performed to compare the seismic response of the single degree of freedom(SDOF) structure on the various types of the foundation. The shallow and pile foundations were made up of diverse mass and different conjunctive condition, respectively. The test specimen consisted of dry sand deposit, foundation, and SDOF structure in a centrifuge box. Several types of earthquake motions were sequentially applied to the test specimen from weak to strong intensity of them, which is known as a stage test. Results from the centrifuge tests showed that the seismic responses of the SDOF structure on the shallow foundation and disconnected pile foundation decreased by the foundation rocking. On the other hand, those on the connected pile foundation gradually increased with intensity of input motion. The allowable displacement of the foundation under the strong earthquake, the shallow and the disconnected pile foundation, have an advantage in dissipating the earthquake energy for the seismic design.

• Journal of Navigation and Port Research
• /
• v.33 no.8
• /
• pp.583-588
• /
• 2009

Generally, the container road transportation can be divided into three types; short distance, long distance and shuttle transportation. Specially, the shuttle service occurs several amounts of container which is same as O/D pairs. Also container vehicle can be divided into three types according to the chassis types of vehicle; only 20-feet container, only 40-feet container and combined chassis trailer. Combined chassis trailers can load two 20-feet containers or one 40-feet container. This paper deals with Vehicle Routing Problem (VRP) for delivering containers considering shuttle service. This problem is similar to the previously studied Shin and Oh (2008), but the characteristics of shuttle service must be considered additionally. We formulate the container shuttle transportation planning problem using combined chassis trailers based on VRP with pick-up and delivery which can visit each node more than one time, and propose an efficient solution procedure.

• Korean Journal of Heritage: History & Science
• /
• v.33
• /
• pp.210-255
• /
• 2000

This study aims to classify the framework and arrangement of interior columns (Naeju) which are used in single-story Buddhist halls into several types, and to develop a theory on the process of changes among those types. Since interior columns are building materials which hold up the roof structure and make partitions in the interior space of halls, their framework and arrangement is closely linked to the development of building technology and is expected to reflect new architectural needs. The kinds of interior columns classified by the shape of framework are goju, chaduju, oepyonju, naepyonju. The arrangement of interior columns can he classified by two methods: One which counts the number of the interior column arrangements in a hall, and the other whose classification relates with the side wall columns - Jeongchibup and yijubup. With the combination of these classifications, we can divide the framework and arrangement of interior columns into 8 types From the remains of Korean and Chinese Architecture, we can presume that before the late-Goryo period, jeongchibup had always been applied in the construction of Buddhist halls, and gamju(column reducing) had only been used in examples of small scale. After the founding of Choseon Kingdom, however, national policy had weakened the economic power of Buddhist temples. Because of that, large-scale outdoor Buddhist mass was replaced by small-scale indoor mass, and for this reason, though the scale of Buddhist halls became smaller, the need for a broad interior space became stronger. Thus in early-Choseon period, reduction of interior columns became widely spread. Those types of framework and arrangement of interior columns where yijubup was applied were developed because the rear interior columns arrangements, in order to expand the interior space, have moved backward. Among these types, yiju-goju and yiju-chaduju were developed for the Buddhist halls with paljak roof(hipped-gabled roof), where the load of their side eaves caused structural problems at the side walls. And oepyonju type was for the small-scale and middle-scale Buddhist halls which needed more interior space but didn't want the extension of roof structure. From the local and periodic distribution of each types, we can conclude that the types jeongchi-goju, jeongchi-chaduju and yiju-chaduju have been settled as typical technique of local carpenters. Oepyonju was developed later than the other types, but for its merit of low cost, it became a popular type across the nation.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.43 no.2
• /
• pp.1-13
• /
• 2020

There are several methods of peak-shaving, which reduces grid power demand, electricity bought from electricity utility, through lowering "demand spike" during On-Peak period. An optimization method using linear programming is proposed, which can be used to perform peak-shaving of grid power demand for grid-connected PV+ system. Proposed peak shaving method is based on the forecast data for electricity load and photovoltaic power generation. Results from proposed method are compared with those from On-Off and Real Time methods which do not need forecast data. The results also compared to those from ideal case, an optimization method which use measured data for forecast data, that is, error-free forecast data. To see the effects of forecast error 36 error scenarios are developed, which consider error types of forecast, nMAE (normalizes Mean Absolute Error) for photovoltaic power forecast and MAPE (Mean Absolute Percentage Error) for load demand forecast. And the effects of forecast error are investigated including critical error scenarios which provide worse results compared to those of other scenarios. It is shown that proposed peak shaving method are much better than On-Off and Real Time methods under almost all the scenario of forecast error. And it is also shown that the results from our method are not so bad compared to the ideal case using error-free forecast.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.12 no.2
• /
• pp.142-149
• /
• 2019

The coils to transmit the electric energy are necessary to charge an electric vehicle wirelessly. There are several types of coils, from basic circular coils to DD-type coils for enhancing the coupling effect between two coils. However, DD-type coils with a good coupling effect between coils have a disadvantage in use because of the structure complexity of the power conversion device of transmitting and receiving side. In this paper, we propose a method to calculate the inductance value and to design the size of the spiral inductor which is convenient to fabricate when the power is transmitted wirelessly by using two coils in free space. Since the bifurcation phenomenon occurs when the XLm value is similar to the load resistance value in the resonator the XLm value was selected to be equal to the minimum load resistance value to minimize this phenomenon, and the inductance value required for the resonator was calculated. In order to realize the calculated inductance value by the spiral inductor, the relationship between the inductance value and the size, the number of turns, the total coil length of a spiral inductor was investigated. In addition, the change of coupling coefficient k according to the horizontal separation of two coils was examined and an appropriate inductor was selected.