• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.377-382
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• 2005

This paper deals with productivity improvement of stevedoring system by pooling opertaions of transport vehicle at automated container terminal. Usually, in traditional container terminals, grouping operations of transport vehicle are applied for container crane because vehicle routing path is simple and vehicle assignment is easy. But this static assignment(SA) operation that arrsign vehicles to container crane ar apron reduces flexibility of vehicles. Therefore, This paper presented 4 dynamic assignment(DA) method to improve efficiency of vehicles. These 4 dynamic assignment method consider present situations of container crane such as sequence(Se), queue time(Qt), productivity(Pr), numeric of vehicle assignment(Nv), numeric of buffer(Nb) at vehicles assignment. At the results, dynamic assignment operation to consider Qt, Nv, Nb is most efficient and by next time, dynamic assignment operation to consider Se is superior more than static assignment operation. but, dynamic assignment operation to consider Pr or Qt of container crane only is inefficient than static assignment operation.

• Journal of Korean Port Research
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• v.10 no.2
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• pp.91-101
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• 1996

Today transportation problems are severer with the increase of the vehicles and travel demand in urban areas, but could not be completely solved with only the expansion of the new transportation facilities. Because the expansion of the new transportation facilities are limited in urban areas. As one of the Transportation System Management(TSM) techniques in this study, the simulation results of the existing signal systems which were operated based upon the peak time periods for increasing the efficiency on the pretimed signalized intersections(PSI) during the different time periods : the AM on-Peak, the AM off-Peak, the PM off-Peak, and the PM on-Peak, were as follows : i) There was no distinct difference in the total traffic volumes concentrated on the signalized intersections during the different time periods, but a considerably big difference in the directional traffic volumes for those time periods. ii) There were about 53% reduction of the average delay and 51% reduction of the fuel consumption when applying the different signal systems to the different time periods regardless of the CBD and Non-CBD. iii) There were about 36% increase of the average delay and 33% increase of the fuel consumption when applying the same signal systems during the peak time periods to the different time periods regardless of the CBD and Non-CBD. Based on the above results, it was concluded that constructing the different signal systems for the different time periods would be better than construction the same ones for those periods on the pretimed signalized intersections in urban areas.

• Journal of Korean Society of Transportation
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• v.20 no.1
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• pp.7-18
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• 2002

To activate public transportation service, Bucheon City built Bus Information System based on Beacon type, and operates it for no.22 line. This research analyzes an effect of BIS operations, and mainly it analyzes far reliability evaluation of bus arrival time information and passenger satisfaction about BIS. As results of reliability evaluation of arrival time information service, it is proven to be practically inappropriate to use as arrival time data because it is not only travel time between each bus stop but also previous travel time history data. In order to improve this matter, neural network model was evaluated as the most outstanding one as result of experiment in applying current arrival time Prediction model. This research cannot help limiting for evaluation of operation effect in Bucheon City because there is no Bus Information System based on GPS type in Korea. For the future ITS model city, in the case of building ITS model city based on GPS type, it is possible to compare two systems relatively. In addition to that, fur the consideration of reliability of bus arrival time information, it is required to develop Predictable model and research factors that affect to bus operation.

• Journal of Information Technology Applications and Management
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• v.16 no.2
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• pp.1-21
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• 2009

The balanced scorecard(BSC) framework is a tool for strategic decision making and task support that aims for efficiency in performance management and strategy execution. BSC evolved from an old performance management practice, which tended to be limited to a finance-only perspective, to a new system of corporate management looking at corporate tasks from a multi-dimensional, future-inclined value perspective. This form of BSC amounts to a framework capable of driving management innovation and renewing the ways in which companies conceive their strategy and perform their operations. Since BSC draws integrally on user participation, it can be expected that users' satisfaction with BSC systems is an important factor in systems' success or failure. However, previous studies of the BSC system have not yet considered it as a theoretical model, specifically examining BSC system and task characteristics. To date, only a few studies have put forward plans for the implementation and use of BSC systems, and these studies have the common limitation of failing to consider the circumstances or theoretical structure of the companies for which a BSC system is being proposed. This paper then begins to fill some of this gap by characterizing the BSC system from the perspective of contingency theories. Contingency theories can be particularly useful in the Korean context in exploring how different companies use the BSC system in ways determined by their unique environmental characteristics, which may also determine the performance factors behind the application of a company's particular BSC system. In order to provide concrete suggestions for implanting and using the BSC system from a contingency theory perspective, this study sets out to determine the relationships between the contingency variables affecting BSC system performance and BSC system property variables(in given cases) through an empirical analysis. The study takes into account the perspective from which contingency theory is to be applied in individual cases, sets contingency and BSC property variables with reference to the BSC system user's environment and BSC system's character, and frames initial hypotheses concerning corporate structure and environmental variables and BSC system performance variables with reference to previous studies. A survey was then conducted on users in Korean companies that have implemented the BSC system in order to verify the research model and understand results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.12
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• pp.42-48
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• 2008

Next generation wireless communication systems require RF transceivers that enable multiband/multimode operations. Polar transmitters are known as good candidates for high data rate systems such as EDGE (Enhanced Data Rates for GSM Evolution), WCDMA (Wideband Code Division Multiple Access), and WLAN (Wireless Local Area Network) because they can obtain high efficiency by using efficient switched-mode RF power amplifiers. In this paper, we investigate the performance of a simple peak windowing scheme for the OFDM (Orthogonal frequency Division Multiplexing) polar transmitter, which requires no change of a receiver structure or no additional information transmission. The approach we employed is to apply the peak windowing scheme to the amplitude modulated signals of the polar transmitter to reduce the PAPR (Peak-to-Average Power Ratio). The BER (Bit Error Rate) and EVM (Error Vector Magnitude) performances are measured for various window types and lengths. The simulation results demonstrate that the proposed algorithm mitigates out-of-band distortion introduced by clipping along with PAPR reduction.

• Journal of Korean Society of Transportation
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• v.21 no.4
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• pp.17-27
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• 2003

In general, an airport access system has influenced on airport terminal operation. The congestion and delay in service facilities at an airport are definitely depended on the patterns of passenger arrival behavior and time spent in a terminal. Therefore, it is necessary to analyze the passenger arrival behavior at an airport to improve the operations at passenger terminal. Passenger arrival patterns to an airport are mainly depended on factors such as the length of access time. reliability of access time. and provision of transport modes, etc. The focus of this paper is to estimate the relationship between the length of access time and passenger's total time spent to board aeroplane. For this, passenger surveys were conducted at the Gimpo International Airport for a large airport and Sacheon Airport for a small size airport. The mathematical relationship between arrival time at an airport prior to the scheduled time of departure(STD) and access time spent was then estimated. It is considered that the results of this study can be used to reduce congestion and delays, thereby to improve the efficiency of the passenger services at the airports.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.9 no.3
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• pp.261-270
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• 2019

With the advent of the Fourth Industrial Revolution, multi-variety production in the up-to-date manufacturing environment is proceeding more rapidly whereby production planning and management have been getting more complicated. Moreover, the need to improve production efficiency through effective operation sequencing is further heightened. Fundamentally, the effective operation sequencing can reduce the set-up of the equipment, efficiently utilize the equipment, shorten the set-up time, and ultimately contribute to productivity improvement. This study deals with the problem of efficient operation sequencing in a situation where a single machine performs multiple operations. The complexity of the problem is very high when compared to the case where only one operation is performed on one machine, which is covered in most existing studies. In this paper, we propose an integer programming model to minimize the number of setups. This study aims at minimizing the number of mold replacement times in the process of processing a given production order for the wiring harness manufacturing process, which is one of the components of automobile electric field. In addition, brief case studies are presented to verify the validity of the proposed mathematical model.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.6
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• pp.127-138
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• 2019

The data response speed is a critical issue of cloud services because it directly related to the user experience. As such, the in-memory database is widely adopted in many cloud-based applications for achieving fast data response. However, the current implementation of the in-memory database is mostly based on the linked list-based hash table which cannot guarantee the constant data response time. Thus, cuckoo hashing was introduced as an alternative solution, however, there is a disadvantage that only half of the allocated memory can be used for storing data. Subsequently, bucketized cuckoo hashing (BCH) improved the performance of cuckoo hashing in terms of memory efficiency but still cannot overcome the limitation that the insert overhead. In this paper, we propose a data management solution called Wall Cuckoo which aims to improve not only the insert performance but also lookup performance of BCH. The key idea of Wall Cuckoo is that separates the data among a bucket according to the different hash function be used. By doing so, the searching range among the bucket is narrowed down, thereby the amount of slot accesses required for the data lookup can be reduced. At the same time, the insert performance will be improved because the insert is following up the operation of the lookup. According to analysis, the expected value of slot access required for our Wall Cuckoo is less than that of BCH. We conducted experiments to show that Wall Cuckoo outperforms the BCH and Sorting Cuckoo in terms of the amount of slot access in lookup and insert operations and in different load factor (i.e., 10%-95%).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.6
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• pp.475-482
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• 2014

This paper presents the results of an experimental feasibility study on low-temperature differential Stirling engines with water spray heat transfer. The water spray enhances the efficiency of the heat transfer from heat sources to the engine and reduces the performance degeneration due to the dead volumes of conventional heat exchangers. A test Stirling engine was developed and an experiment was conducted to determine the characteristics for the initial start-up, steady-state operation, and power output for various flow rates and temperatures of hot supply water. The test results showed that larger flow rates led to reductions in the minimum working temperature of the hot water at start-up. During a series of steady-state operations, higher flow rates and temperatures increased the working speed. Furthermore, the work per cycle and power output were also increased. Eventually, the test Stirling engine had a power level of 0.05 W. Based on this, further research will be conducted to obtain a higher power output and investigate various applications.

• KIISE Transactions on Computing Practices
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• v.23 no.12
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• pp.651-659
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• 2017

IT(Information Technology) has focused on infrastructure-technologies in the past but now focuses on IT service. Many companies strive to save costs and improve IT services. For this reason, they strive to implement a good internalization of ITSM (IT Service Management) by developing ITSM systems based on ITIL (Information Technology Infrastructure Library) from the late 2000s. In particular, IT service operations are one of the structure elements of ITIL version 3 and are highly related to the internalization of ITSM. However, in spite-of-the successful implementation of ITSM, the efficiency of IT service management has not improved due to iterative issues. Therefore, this study developed a user-centered training system by defining the iterative issue guidelines and implementing a database. The implemented user-centered training system provided IT service users with regular training services to produce a good solution for iterative issues after connecting the operation part of the ITSM system. Based on the results of this study, we expect that the proposed ITSM system will contribute to efficiently managing IT services by improving the limitations of IT service operation in the ITSM system.