• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11B
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• pp.972-984
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• 2003

In this paper, new on-line routing algorithms with a bandwidth constraint are proposed. The proposed algorithms may be used for a dynamic LSP setup in MPLS network. We extend the WSP algorithm, the SWP algorithm and a utilization-based routing algorithm into the proposed algorithms by slightly modified K-shortest loopless path algorithms. The performances such as accepted bandwidth, accepted request number and average path length of the proposed and the previous algorithms are evaluated through extensive simulations. All simulations are conducted under the condition that any node can be an ingress or egress node for a LSP setup. The simulation results show that the proposed algorithms have the good performances in most cases in comparison to the previous algorithms. Under the heavy load condition, the algorithms based on the minimum hop path perform better than any other algorithms.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.310-312
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• 2005

An out-of-step condition results from the loss of the synchronism of the generators. A disturbance in a power system causes the generator angle to oscillate. When there is a severe disturbance such as a heavy current fault loss of major generation or loss of a large block of load the oscillation can be severe and even increase largely and finally the out-of-step condition may occur During the power swing and out-of-step conditions, the a apparent impedance at a relay location changes, and the power flow also changes as the angle difference is varied. This paper presents a method to analyze the trajectory of complex power during a power swing and out-of-step condition. The trajectory of the complex power is analyzed when a power swings and a fault occurs. Moreover, the complex power is analyzed when the ratios between the voltages at both sides and the line impedances are changed. These methods are verified through simulation using the ATP/EMTP MODELS.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.321-327
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• 1998

This paper presented a case study on the application of on-line wear monitoring technique to a high duty air-turbo-compressor system. Main objects monitored were a gear unit and metal bearings, both shown frequent troubles due to the severe operation conditions at heavy dynamic load. The air-turbo-compressor system needs secure condition monitoring because it is one of the main utilities in steel making industry. Temperature and vibration characteristics have been mainly on-line monitored in this system for a predictive maintenance; however, it has been shown that they are not fairly good enough to give an early warning prior to the machine failure. In this work, an on-line Opto Magnetic Detector(OMD) was implemented for an on-line wear monitoring, which quantitatively measured the contamination level of both ferrous and non-ferrous wear particles by detecting the change in optical density of used oil. Results showed that the application of on-line OMD system was satisfactory in diagnosis of the machine system.

• English Language & Literature Teaching
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• v.16 no.4
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• pp.239-265
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• 2010

This study investigates the effects of corpus-based vocabulary tasks on the acquisition of English vocabulary in an attempt to explore the influence of corpus use on EFL pedagogy. For this to be realized, a total of 40 Korean high school students participated in the study over a 4-week period. An experimental group used a set of corpus-based tasks for vocabulary learning, whereas a control group carried out a traditional task (i.e., the L1-L2 translation) for vocabulary learning. To assess learning gains, the students were asked to complete the pre- and post-treatment tests measuring the word form, meaning, and use aspects of target lexical items. Results of the study indicate that in the experimental group the corpus-based vocabulary tasks were beneficial for the learning of word forms and use. In particular, corpus-based benefits were greatest in the low-proficiency EFL learners' collocational aspects of vocabulary use. On the other hand, in the control group, the traditional vocabulary tasks benefited the meaning aspects of target vocabulary items the most. In addition, survey results revealed that most students were positive about the corpus-based learning experience although some expressed reservations about the heavy cognitive load and the time-consuming nature of the analysis of corpus data primarily due to learners' lack of language proficiency.

• Spatial Information Research
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• v.11 no.4
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• pp.509-518
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• 2003

Impervious surface affects urban climate, flood, and water pollution. With a higher paved rate, expanded heat containing capacity of buildings and roads raises atmospheric temperature, and increased quantity of the outflowed water brings flood during a heavy downpour. Moreover, increased non-point source pollutant load is accountable for water pollution. In this regard, it is definitely important to research and keep monitoring the current situation of paved surface, which influences urban ecosystem, disaster and pollution. In fact, collecting information on urban paved surface, which requires the time and expense, is very difficult due to its complicate structure. In order to solve the problem, this study suggested a method to utilize satellite image data for efficient survey on the current condition of paved surface. It analyzed the paved surface condition of Anyang-si by using IKONOS image and discussed the usefulness and limitation of this method.

• Journal of IKEEE
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• v.21 no.2
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• pp.115-122
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• 2017

In vehicular safety service, every vehicle broadcasts Basic Safety Message (BSM) periodically to inform neighbor vehicles of host vehicle information. However, this can cause network congestion in a region that is crowded with vehicles resulting in a reduction in the message delivery ratio and an increase in the end-to-end delay. Therefore, it could destabilize the vehicular safety service system. In this paper, in order to improve the congestion control and to consider the hidden node problem, we propose a congestion control scheme using entire network congestion level estimation combined with transmission power control, data rate control and time slot based transmission control algorithm. The performance of this scheme is evaluated using a Qualnet network simulator. The simulation result shows that our scheme mitigates network congestion in heavy traffic cases and enhances network capacity in light traffic cases, so that packet error rate is perfectly within 10% and entire network load level is maintained within 60~70%. Thus, it can be concluded that the proposed congestion control scheme has quite good performance.

• Journal of Korean Association for Spatial Structures
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• v.15 no.3
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• pp.51-60
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• 2015

Recently, the concept of damped outrigger system has been proposed for tall buildings. But, structural characteristics and design method of this system were not sufficiently investigated to date. In this study, the dynamic response control performance of outrigger damper has been analyzed. To this end, a simplified analysis model with outrigger damper system has been developed. An artificial wind of 1000 seconds with 0.1 second time steps was generated by using a Kaimal spectrum. Analysis results show that outrigger damper system is more effective up to 20-23% in the control of dynamic response compared to conventional outrigger system. The increase of outrigger damper capacity usually results in the improved control performance. However, it is necessary to select that proper stiffness and damping values of the outrigger damper system because, the outrigger damper having large capacity is result in heavy financial burden.

• Journal of Korean Association for Spatial Structures
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• v.16 no.1
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• pp.95-104
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• 2016

Recently, the concept of damped outrigger system has been proposed for tall buildings. But, structural characteristics and design method of this system were not sufficiently investigated to date. In this study, the dynamic response control performance of outrigger damper has been analyzed. To this end, a simplified analysis model with outrigger damper system has been developed. Use the El Centro seismic(1940, NS) analysis was performed. Analysis results, on the top floor displacement response to the earthquake response, did not have a big effect. However, acceleration response control effect was found to be excellent. The increase of outrigger damper capacity usually results in the improved control performance. However, it is necessary to select that proper stiffness and damping values of the outrigger damper system because, the outrigger damper having large capacity is result in heavy financial burden.

• Journal of Korean Association for Spatial Structures
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• v.8 no.6
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• pp.75-83
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• 2008

The R.C Building will be superannuated as time passes by heavy load and serviceability. Methods of damage detection are used a visual angle of human or non-destructive test in the R.C Building. In case of the latter, Problems of damage detection are occurred to directions of steel bar. Elastic waves are difficult to assaying test using 1 axial type of accelerometer in reinforced concrete. In this study, fundamental studies for estimations using 3 axial type of accelerometer are discussed oscillator of elastic waves when embedded glass tube pipe or steel bar in flexible concrete specimens.

• The Journal of Korean Association of Computer Education
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• v.13 no.3
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• pp.13-23
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• 2010

The revised 7th education course of information implies that students use variety of information devices to solve the common problems and it also includes the programming education for improving problem-solving abilities. Not only improving problem-solving abilities but also developing thinking skill is expected in programming education. However, traditional programming education is teacher-oriented and focused on language syntax. Accordingly, students have heavy cognitive load and it decrease students' interest of programming. Therefore, in this paper, a instructional method of programming using educational robot is proposed to improve interest of elementary students in concretive operation stage for effectiveness of programming education. Additionally, results of experiments show that proposed robot programming instructional method can be applied in elementary education.