• Journal of the Korean Society for Railway
• /
• v.7 no.3
• /
• pp.264-270
• /
• 2004

The hub-and-spoke strategy is widely used in the field of transportation. At the field of rail transportation, however, it is difficult that we find an application case of this strategy because of modal characteristics. According to the fast growth of containerization and the development of transshipment technology, presently, the hub-and-spoke strategy is introduced by operators on actual European rail freight transportation. However, it is hardly to find empirical studies evaluating the applicability of transportation strategy. In this context, this study analyzed the applicabilities of hub-and-spoke strategy in the actual network of European rail freight. For the application and evaluation of the characteristics of hub-and-spoke strategy, it utilized a service network design model for rail freight. Utilizing this model, it analyzed the efficiency of furnished rail freight services, the potential locations of hubs, the characteristics of O-D flows by the types of trains and service links, and the types of paths of O-D flows. Finally, it proposed some implications and the further study topics.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.717-718
• /
• 2015

전동기를 설계 시 자기등가회로법은 전동기의 세부 형상에 크게 구애를 받지 않기 때문에, 공간고조파법과 수치해석기법에 비해 유용하다. 이 논문에서는 Spoke type PMSM(Permanent Magnet Synchronous Motor)의 회전자 자기등가회로를 설계하였다. 회전자 자기등가회로를 통해, 마그네틱 토크 성분을 구성하는 공극자속밀도 수식을 이끌어 낼 수 있다. 이를 통해, Spoke type PMSM은 마그네틱 토크가 주 토크이기 때문에, 공극 자속밀도 및 형상치수비를 이용하여 전동기의 크기를 계산하였다.

• 한국연소학회:학술대회논문집
• /
• 2003.05a
• /
• pp.41-50
• /
• 2003

Numerical analysis was carried out to investigate performance and combustion characteristics of KSR-III liquid rocket engine with several types of baffle. To evaluate the change of performance and combustion characteristics with several types of baffle, the first numerical calculations were performed about baffle tab, radial blade baffle, and hub-and-spoke baffle. Then radial blade and hub-and-spoke baffle were determined to design two types of the KSR-III engine with baffles. Also to investigate the effect of injector arrangements and baffle positions, two types of radial blade baffle were calculated then numerical calculations were carried out with changing axial length of radial blade I, II and hub-and-spoke baffle. While axial length of baffle effected to performance very small, injector arrangement effected to performance largely through calculations of radial blade I, II. From the viewpoint of combustion instability, hub-and-spoke baffle controlled combustion instability effectively and there was the performance of hub-and-spoke baffle between radial blade I and II.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.53 no.3
• /
• pp.135-142
• /
• 2004

In this paper, the magnetic circuit characteristics and the current/torque analysis of a Spoke Type permanent magnet motor have been researched, compared with the SPM Type motor. In the magnetic circuit analysis, the characteristic of air-gap flux density has been analyzed according to the variation of the number of pole and the ratio of magnet height to arc length using finite element method and circuit equations. Moreover, the electromagnetic and the reluctance torque have been analyzed by the current profile, which is obtained from the variation of turn-on angle, and these informative data has been utilized for the overall characteristics of the Spoke Type BLDC motor.

• Korean Management Science Review
• /
• v.28 no.3
• /
• pp.1-13
• /
• 2011

Hub-and-spoke transportation network is a powerful and useful network structure that takes full advantage of economies of scale on routes between hubs. In recent studies, the network structure is extended to hybrid hub-andspoke that allows direct transportation between spokes. In this study, we considered more extended network structure which is called hybrid multiple hub-and-spoke that has multiple hubs and allows direct transportation between spokes. We developed a mathematical optimization model for automotive service parts transportation planning under hybrid multiple hub-and-spoke network structure. The model suggests a long-term transportation route planning and a short-term vehicle assignment planning. The model is verified by simulation and validated in real world application to Hyundai Mobis automotive service parts transportation planning. From the simulation result, the model reduced the transportation cost about 24.7%, the total distance about 6.8% and the CO2 emissions about 8.8%. In real world application for 6 months from July to December 2010, the model reduced the transportation cost about 9.1% by changing the long-term transportation route without daily vehicle assignment planning.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2006.05a
• /
• pp.1036-1041
• /
• 2006

본 연구에서는 허브와 스포크의 입지선정과 차량 경로가 통합된 hub-and-spoke 네트워크 설계문제를 다룬다. Hub-and-spoke 네트워크는 대량화와 공동화를 통해 물류효율화를 실현하기 위한 대표적인 구조로 물류시스템에서 흔히 사용되고 있다. 이러한 물류시스템에서 물류비용의 절감과 고객서비스 향상을 위한 효율적인 수송네트워크 설계는 매우 중요하다. 전통적인 hub-and-spoke 네트워크 설계문제에서 각 스포크의 위치와 화물량이 미리 주어진 상황에서 허브의 입지를 결정하였다. 하지만 스포크 역시 스포크가 담당하는 고객들의 위치와 담당 영역에 따라 그 위치와 수, 그리고 화물량이 변할 수 있다. 또한 정확한 비용산출을 위해서는 스포크에서 고객으로의 수집과 배달을 위한 차량경로가 함께 고려되어야 한다. 다루는 수송망 설계문제는 상호 관련성 있는 여러 부분문제가 결합된 통합문제로써 이를 해결하는 방법으로 기존의 발견적 방법에 의한 순차적 기법은 한계가 있다. 본 연구에서는 공생 진화알고리듬 기반의 방법론을 채용하여 다루는 수송망 설계문제를 동시에 통합적으로 해결할 수 있는 알고리듬을 개발한다. 실험을 통해 개발한 알고리듬의 우수성과 그 적용성을 보인다.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.31 no.2
• /
• pp.141-155
• /
• 2006

In this paper, we address an extended hub-and-spoke transportation network design problem (EHSNP). In the existing hub location problems, the location and number of spokes, and shipments on spokes are given as input data. These may, however, be viewed as the variables according to the areas which they cover. Also, the vehicle routing in each spoke needs to be considered to estimate the network cost more correctly. The EHSNP is a problem of finding the location of hubs and spokes, and pickup/delivery routes from each spoke, while minimizing the total related transportation cost in the network. The EHSNP is an integrated problem that consists of several interrelated sub-problems. To solve EHSNP, we present an approach based on a symbiotic evolutionary algorithm (symbiotic EA), which are known as an efficient tool to solve complex integrated optimization problems. First, we propose a framework of symbiotic EA for EHSNP and its genetic elements suitable for each sub-problem. To analyze the proposed algorithm, the extensive experiments are performed with various test-bed problems. The results show that the proposed algorithm is promising in solving the EHSNP.

• Journal of Korean Association for Spatial Structures
• /
• v.17 no.1
• /
• pp.31-40
• /
• 2017

The objective of this study is to analysis the mechanical characteristics and nonlinear behaviors on the geometric nonlinear behavior of a cable spoke wheel roof system for long span lightweight roof structures. The weight of a cable spoke wheel roof dramatically can reduce and the cable roof system can easily make the required rigidity and shape by the sag ratio and pretension forces. Determining the pretension and initial sag of cable roof system is essential in a design process and the shape of roof is changed by pretension. The nonlinear behavior of flexible cable system has greatly an affect on the sag and pretension. This paper will be carried out analyzing and comparing the tensile forces and deflection of a cable spoke wheel system for the large span retractable roof, and analyzed to deflections and tensile forces by the post height of center hub. The double arrangement of a spoke wheel system with reverse curvature works more effectively as a load bearing system, the pretension can easily increase the structural stiffness. The cable truss system can carry vertical load in up and downward direction, and act effectively as load bearing elements.

• Journal of Korean Society of Transportation
• /
• v.22 no.3 s.74
• /
• pp.167-177
• /
• 2004

The Hub-and-spoke strategy is widely used in the field of transportation. According to containerization and the development of transshipment technology, it is also introduced into European rail freight transportation. The objective of this article is to develop a service network design model for rail freight transportation based on the Hub-and-spoke strategy and efficient algorithms that can be applied to large-scale network. Although this model is for strategic decision, it includes not only general operational cost but also time-delay cost. The non-linearity of objective function due to time-delay factor is transformed into linearity by establishing train service variables by frequency. To solve large scale problem, this model used a heuristic method based on decomposition and three newly-developed algorithms. The new algorithms were examined with respect to four test problems base on the actual network of European rail freight and discussed the accuracy of solutions and the efficiency of proposed algorithms.

• Proceedings of the KIEE Conference
• /
• 2008.04c
• /
• pp.35-37
• /
• 2008

This paper deals with a design to improve operating characteristic of spoke type BLDC motor. The rotor and stator is redesigned as rounding teeth of stator and pole surface of rotor. Result, cogging torque is reduced greatly. The Finite Element Analysis(FEM) is used to characteristics. The Prototype has been manufacturing to confirmed the validity of the proposed technique.