• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.560-563
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• 1998

For the next generation railway brake system, a disc brake which can be operated directly and electrically is strongly expected. This paper deals with newly developed disc brake actuator using giant magnetostrictive materials(GMM) which can be integrated with disc brake. Regarding the brake system performance, a better delay time was also attained which can be integrated with disc brake. Regarding the brake system performance, a better delay time was also attained which will contribute to shorten a stopping distance.

• Journal of the Korea Society for Simulation
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• v.9 no.2
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• pp.89-102
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• 2000

In this paper, we consider an optimal allocation of constant service efforts in queueing network to maximize the system throughput. For this purpose, using the perturbation analysis, we apply a stochastic optimization algorithm to two types of queueing systems. Our simulation results indicate that the estimates obtained from a stochastic optimization algorithm for a two-tandem queuing network are very accurate, and those for closed loop manufacturing system are a little apart from the known optimal allocation. We find that as simulation time increases for obtaining a new gradient (performance measure with respect to decision variables) by perturbation algorithm, the estimates tend to be more stable. Thus, we consider that it would be more desirable to have more accurate sensitivity of performance measure by enlarging simulation time rather than more searching steps with less accurate sensitivity. We realize that more experiments on various types of systems are needed to identify such a relationship with regards to stopping rule, the size of moving step, and updating period for sensitivity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.1
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• pp.83-85
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• 2016

The OFDM with LS signal detection performs worse in fast time varying channels as the channel matrix has higher chance of becoming ill-conditioned. Various regularization methods are applied to avoid performance degradation in LS signal detection. In this paper, we proposed a CGLS method with the stopping criteria imposed by the characteristics of the modulation method, which shows performance comparable to that of the optimal LMMSE.

• Journal of the Korean Professional Engineers Association
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• v.45 no.6
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• pp.28-32
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• 2012

Namhae chemical is one of the largest fertilizer manufacturing company in Korea which company has operating 4 unit agitator gear boxes and producing variety kinds of fertilizer production. The gearbox operating temperature of agitator is approximated in $55^{\circ}C{\sim}90^{\circ}C$ and required to keep operating continuous without stopping. The system required high performance oil and longer oil drain interval as limited workforce in maintenance team. It was lubricated by mineral gear oil of ISO VG 320 and also need to change to new oil frequently. Namhae Chemical would expect to keep stable operating condition without shut down and consider, lower cost of operation and equipment protection.

• Journal of Korean Society for Quality Management
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• v.46 no.3
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• pp.411-424
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• 2018

Purpose: The purpose of this study is to improve submarine TACM launcher system safety device performance. Methods: In this study, EPLD(Electrically Programmable Logic Device) control and time sharing method to the safety device actuator motor and discrete signal processor in launch control panel were used to resolve unusual performance of safety system. Results: The result of this study are as follows; First, sporadic stopping of safety device actuator motor due to insufficient In-Rush current was resolved. Second, repeat of safety device condition as lock & release due to chattering for motor activating was resolved. Third, simultaneous release function for safety device actuator was available. Conclusion: The unusual performance of function for submarine TACM launcher system was overcame by applying EPLD control and time sharing method. The suggestions were proved by performance test in the pressure chamber. The results of this study enhanced survivability of ${\bigcirc}{\bigcirc}{\bigcirc}$ class submarine from enemy torpedo.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.10
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• pp.898-906
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• 2002

Antilock Brake System (ABS) is designed to prevent wheels from being locked-up under emergency braking of a vehicle. Therefore it improves directional stability of the vehicle, shortens stopping distance, and enhances maneuvering during braking, regardless of road conditions. Hardware In-the-Loop Simulation (HILS) is an effective tool for design Performance evaluation and test of vehicle subsystems such as ABS, active suspension, and steering systems. This paper describes a HILS model for ABS/ ASR(Acceleration Slip Regulation) system applications. A fourteen degrees-of-freedom vehicle dynamics model is simulated in an alpha-chip processor board. The proposed HILS system is tested with a basic ABS control algorithm. The design and implementation of HILS system for the ABS ECU(Electronic Control Unit) development of commercial vehicle are presented. The results show that the proposed HILS system can be used to test the performance, stability, and reliability of a vehicle under braking.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1161-1175
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• 2018

An unexpected event could be easily followed by a large secondary accident due to the limitation in sight of drivers in road tunnels. Therefore, a series of automated incident detection systems have been under operation, which, however, appear in very low detection rates due to very low image qualities on CCTVs in tunnels. In order to overcome that limit, deep learning based tunnel incident detection system was developed, which already showed high detection rates in November of 2017. However, since the object detection process could deal with only still images, moving direction and speed of moving vehicles could not be identified. Furthermore it was hard to detect stopping and reverse the status of moving vehicles. Therefore, apart from the object detection, an object tracking method has been introduced and combined with the detection algorithm to track the moving vehicles. Also, stopping-reverse discrimination algorithm was proposed, thereby implementing into the combined incident detection processes. Each performance on detection of stopping, reverse driving and fire incident state were evaluated with showing 100% detection rate. But the detection for 'person' object appears relatively low success rate to 78.5%. Nevertheless, it is believed that the enlarged richness of image big-data could dramatically enhance the detection capacity of the automatic incident detection system.

• Journal of Korean Society of Transportation
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• v.29 no.3
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• pp.115-122
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• 2011

This paper investigates the accuracy of the vehicle pre-braking speed estimated based upon measured skidding distance. Driver ordinarily takes sudden braking when urgent situation is developed in the front or when the driver is involved in an unexpected situation, and the driver may be inflicted upon an accident depending on the required stopping distance. Among factors influencing the stopping distance of vehicle such as recognition response time of driver, performance of vehicle's braking device, and state of road surface etc, pre-braking speed is seemingly the most important influencing factor. Currently, in the investigating section of traffic accidents, the state of overspeed is determined by the pre-skidding speed calculated based on the length of skid mark. In order to identify the accurate cause of the accident, it is strongly recommended that estimation of pre-braking speed should be estimated taking into account speed reduction during transient time. In this study, we propose a method for estimating more accurate exact speed information of vehicle at the time of traffic accident. The outcomes from this study potentially help better understanding of the characteristics of vehicle for traffic safety in the future.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.10
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• pp.67-74
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• 2007

Turbo code, a kind of channel coding technique, has ben used in the field of digital mobile communication system if the number of iterations is increased in the several channel environments, my further iteration results in very little improvement, and requires much delay and computation in proportion to the number of iterations. In this paper, it proposes an efficient stopping rules for the iteration process in turbo decoding. By using absolute mean values for the LLR difference values between the first and second decoder in the present decoding process, the proposed algorithm can largely reduce the average number of iterations without BER performance degradation in all SNR regions. As a result of simulation, the average number of iterations of proposed algorithm is reduced by about $18.25%{\sim}20.58%$ compared to SDR algerian in the lower SNR region, and is reduced by about $22.96%{\sim}28.74%$ compared to method using variance values of extrinsic information in the upper SNR region.

• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.71-78
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• 2008

This study aims to identity the age group where driving performance significantly decreases based on the data collected from the Korea Transportation Safety Authority's driver aptitude tests in 2006. The test includes following six driving simulator-based tests: estimation of moving objects' speed, estimation of stopping distance, three tests for drivers' multi-task ability, and kinetic depth perception. These six test results were utilized for the identification of the age threshold applying the CART technique, suggesting driving ability significantly be decreased over 50s. This finding was confirmed by two analyses using the accident history data containing the information of accident and non-accident drivers and the degree of accident severity. The results of this study imply that accident prevention efforts should be enhanced over a wider range of age group than the current practice where the age of 65 is generally applied for the threshold dividing senior and non-senior driver groups.