• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.5
• /
• pp.102-107
• /
• 2014

Because of high oil prices and emission gas problems, many governments tighten regulation of fuel economy and emission gas. For Passenger car, there are many researches for plug-in hybrid electric vehicles and they are being manufactured. On the other hand, there are few researches for plug-in hybrid electric bus that is heavy commercial vehicle. In this study, analysis of fuel economy for series plug-in hybrid electric bus according to engine operation strategy based on simulation is conducted. Forward simulator is developed using Autonomie. Engine operation strategies consist on constant engine operation strategy and engine on/off operation strategy. Considering the engine operation strategy, results of vehicle speed, engine operating points and fuel economy are obtained and analyzed. As a result, engine on/off operation strategy has more advantage than constant engine operation strategy in terms of fuel economy.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.12 no.2
• /
• pp.140-149
• /
• 2000

A comparative analysis was peformed on the operation cost at partial loads between ice storage systems with the two conventional control strategies, i.e., storage priority and chiller priority. The storage priority control is shown to be more economic for small cooling loads, while the chiller priority control is superior when the cooling load is as large as the design value. Based on this finding, a new control strategy is devised for an ice-storage system to minimize the operation cost at any cooling load. The new control strategy is found to be comparable to the chiller priority for large cooling loads, while it is more economic for small loads compared to the conventional control strategies. The practicality of the new control strategy is also confirmed through a performance test applying the new control strategy to an existing ice-storage system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.16 no.6
• /
• pp.574-583
• /
• 2004

In this study, the operation strategy of the radiant floor cooling is evaluated in terms of indoor environmental conditions and energy consumption through simulations using the TRNSYS comparing the existing cooling operation. The operation strategy during continuously operated for cooling is proposed that a representative room had additional equipments and other rooms were operated with only a radiant floor cooling system and that system and control method for cooling are varied with period while intermittently operated for cooling. Specifically, when there are no people in the room, rooms were operated by only radiant floor cooling system using cooling storage and when people are occupied, rooms were operated by dehumidification and supplementary cooling device with radiant floor cooling system. The results of this study show that proposed operation strategy can stably maintain the set room air temperature and can reduce the energy consumption compared to the existing cooling method during continuously operated for cooling. While intermittently operated for cooling, the difference of set room air temperature by proposed operation strategy does not happen, satisfying comfort standards and the radiant floor cooling can expect to supply stable electric power because of decreasing demand for peak electric power of energy consumption.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.11 no.3
• /
• pp.401-413
• /
• 1999

An ice storage cooling facility with cooling capacity of 150㎾ has been constructed for the purpose of developing optimal design and control strategy for an ice storage system. As the first step to this purpose, a computer program has been developed to simulate the operation of the ice storage system and examined precisely by comparing the results with those measured from the test facility. With the simulation program verified from the comparison, a design procedure has been developed to determine the minimum capacity required for each operation strategy available commercially. It is shown that the minimum sizes of the chiller and the storage tank are strongly dependent on the control strategy, i.e., chiller priority or storage priority, but less affected by the arrangement method, i.e., chiller upstream or chiller downstream.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.6
• /
• pp.653-661
• /
• 2017

This study compares and analyzes the operation costs of traditional and direct delivery strategies considering carbon emissions. For the determination of minimum operation costs and order quantity, we use the Economic Order Quantity (EOQ) model, which is the proper method for calculate the operation costs by logistics strategy. Using the classical EOQ model, we expand the EOQ model considering carbon emissions and domestic logistics environment. We conduct an empirical study on two agri-food logistics strategies under limitation of the carbon emissions using the expanded EOQ model. From the results of the empirical study, we find that the operation costs of direct delivery strategy are about 50% lower than those of the traditional strategy. Economic order quantity is also smaller than that of the traditional strategy. These results indicate that agri-food products can be transported quickly and freshly under direct delivery strategy. Consequently, considering carbon emissions, direct delivery logistics strategy are analyzed to have more positive effect on economic and environmental issues than existing logistics strategy. It is judged that direct strategy will also increase the freshness of agricultural products.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.17 no.2
• /
• pp.156-164
• /
• 2005

A comparative analysis of an ice storage system has been performed on the operation cost for the four control strategies, i.e., chiller priority and chiller downstream, chiller priority and chiller upstream, storage priority and chiller upstream, storage priority and chiller downstream. Main components of the ice storage system are an ice-on-coil storage tank and a screw compressor chiller. With the simulation program, the operation cost has been evaluated from the economics of an ice storage system. It is found that the operation cost of the ice storage system is strongly dependent on the control strategy, i.e., chiller priority or storage priority, but less affected by the arrangement method, i.e., chiller upstream or chiller downstream. In case of the maximum load day, the control strategy with chiller priority and chiller upstream is supposed to obtain the reduction of operation cost. However, it is found that the control strategy with storage priority and chiller downstream is the best economical operation for most summer seasons except the maximum load day.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.6 no.1
• /
• pp.71-98
• /
• 1998

The study proved the fitness between competitive strategy and service operation strategy of service companies. The competitive strategy of a corporation is a major strategy playing the role of bridge linking both corporate strategy and functional strategy. And it is a choice of method how to win competitors in given area. There have been such a specific methodologies for acquiring competitive advantage as Porters competitive strategy, Miles and Snows adaptive strategy, and Life cycle strategy. But, many scholars have pointed that its more important for high corporate performance to determine the competitive strategy of a corporation fitting the external environment and internal structure. So its needed for successful cost-leadership or differentiation strategy to differentiate organizational function, resources, and various organizational factors. But there have been no methodologies or practical guidelines fitting competitive strategy, corporate structure, and external environment in sprite do service corporations growth. So, the study proved the fitness between competitive strategy and service operation structure in Airlines after selecting service structural elements necessary for strategic management.

• Journal of the Korean Data and Information Science Society
• /
• v.15 no.1
• /
• pp.11-20
• /
• 2004

The purpose of this paper was to reveal Service Operation Strategy for the Internet shopping mall based on the types of internet users' market segmentation focus on the internet shopping behavior and e-service quality. In this paper, we examined internet shopping behavior and internet service quality factor depend on the types of internet users' group empirically. The empirical study result identifies the main decision factor depend on the types of internet users' group. On the basis of these result, Service Operation Strategy for the internet shopping mall has been suggested.

• KIEE International Transactions on Power Engineering
• /
• v.5A no.2
• /
• pp.144-151
• /
• 2005

This paper presents a framework for determining control strategies against unwanted tripping actions during relay operation that plays a very important role in cascading events leading to voltage collapse. The framework includes an algorithm for quick identification of possible zone 3 relay operation during voltage instability. Furthermore, it comes up with the control strategy of load shedding at the selected location with active power and relay margin criteria. In addition, Quasi Steady-State (QSS) simulation is employed to obtain time-related information that is valuable in the determination of control strategy. As a case study, an example applying the framework is shown with the modified New England 39-bus system.

• Proceedings of the KIPE Conference
• /
• 2005.07a
• /
• pp.30-32
• /
• 2005

In this paper, voltage control strategy for maximum torque operation of stator flux-oriented induction machine drive in the field-weakening region is proposed. In a conventional stator flux-oriented (SFO) induction machine drive system of the maximum torque capability cannot be obtained. The field-weakening method is used to vary the stator-flux reference in proportion to the inverse of the rotor speed. The proposed algorithm, based on the voltage control strategy, ensures the maximum torque operation over the field-weakening region. The proposed algorithm, voltage control strategy for maximum torque operation of capability, which is insensitive to the variation of machine parameters In the field-weakening region. The proposed algorithm is verified by simulation.