• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.717-720
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• 2000

Event-driven communication protocols such as CAN(Controller Area Network) have inherent packet delays due to the contention process for the use of network medium. These delays are stochastic in nature because most packets arrive at random time instants. The stochastic property of the delay adversely influences the control system's performance in terms of stability, responsiveness and steady-state error. Another problem for safety-critical application such as brake-by-wire systems is the reliability of the communication modules that can fail abruptly. This paper deals with two methods to overcome the above problems : (i) scheduling method that can maintain packet delays under some acceptable level, and (ii) redundancy management of communication modules that prescribes dual-redundancy modules' behavior when one of them fails.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.12
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• pp.872-878
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• 1988

During the past few years, a great deal of attention has been directed to the application of superconductivity to the electrical systems such as superconducting power transmission lines, superconducting magnet energy storage and so on. Yet in order to develop the practical model of these electrical equiqments utilizing suprconductivety and other phenomena at cryogenic temperautre, it is necessary to know the dielectric behaviour of insulating materials at cryogenic temperature in view of reliability, safety and economy of these machines. Investigation of dielectric properties of cryogenic liquids is very important due to the dual role of those as the dielectric and cooling medium. In this study, we investigated results measured over several kinds of dielectric characteristics of liquid nitrogen taking into consideration for application of high Tc superconductor. Dependence of breakdown voltage of gap width, polarity and pressure is reported in this paper and time delay characteristics of breakdown is also the subject of this discussion.

• Journal of Korea Multimedia Society
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• v.11 no.6
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• pp.816-827
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• 2008

In this paper, two-stage pipelined floating-point arithmetic unit (FP-AU) is designed. The FP-AU processor supports seventeen operations to apply 3D graphics processor and has area-efficient and low-latency architecture that makes use of modified dual-path computation scheme, new normalization circuit, and modified compound adder based on flagged prefix adder. The FP-AU has about 4-ns delay time at logic synthesis condition using $0.18{\mu}m$ CMOS standard cell library and consists of about 5,930 gates. Because it has 250 MFLOPS execution rate and supports saturated arithmetic including a number of graphics-oriented operations, it is applicable to mobile 3D graphics accelerator efficiently.

• Journal of Information Processing Systems
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• v.15 no.5
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• pp.1231-1242
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• 2019

This paper presents a two-dimensional attention-based long short-memory (2D-ALSTM) model for stock index prediction, incorporating input attention and temporal attention mechanisms for weighting of important stocks and important time steps, respectively. The proposed model is designed to overcome the long-term dependency, stock selection, and stock volatility delay problems that negatively affect existing models. The 2D-ALSTM model is validated in a comparative experiment involving the two attention-based models multi-input LSTM (MI-LSTM) and dual-stage attention-based recurrent neural network (DARNN), with real stock data being used for training and evaluation. The model achieves superior performance compared to MI-LSTM and DARNN for stock index prediction on a KOSPI100 dataset.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.7
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• pp.550-557
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• 2017

Ionospheric delay, which affect the accuracy of GNSS positioning, is generated by electrons in Ionosphere. Solar activity level, region and time could make change of this delay level. Dual frequency receiver could effectively eliminate the delay using difference of refractive index between L1 to L2 frequency. But, Single frequency receiver have to use limited correction such as ionospheric model in standalone GNSS or PRC(pseudorange correction) in Differential GNSS. Generally, these corrections is effective in normal condition. but, they might be useless, when TEC(total electron content) extremely increase in local area. In this paper, monitoring algorithm is proposed for local ionospheric anomaly using multiple reference stations. For verification, the algorithm was performed with specific measurement data in Ionospheric storm day (20. Nov. 2003). this algorithm would detect local ionospheric anomaly and improve reliability of ionospheric corrections for standalone receiver.

• Journal of Korean Society of Transportation
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• v.20 no.5
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• pp.23-31
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• 2002

The headway of vehicles entering an intersection is closely related with the saturation flow rate and is a basic parameter required for determining the saturation headway and the start-up lost delay. Since such headway value reflects the drivers' behaviors and features of the intersection, all intersections don't have an equal value, but are affected by number and location of their lanes, changing types, local characteristics and time zone. Accordingly, this study attempted to suggest proper values on the basis of data by investigating headway in lanes. Number of exclusive through lanes was divided into single lane, double lanes and triple lanes, the locations of lanes were divided into inside lane, central lane and outside lane. As a result of investigating the headway, single through lane, double through lanes-inside lane, and triple through lane-outside lane showed as 1.73 sec., 1.71 sec. and 1.93sec., respectively. The result of calculating the area factor of business areas by fixing 1.00 for the residental area and applying relation between headway and saturation flow rate was 0.96. In the case of start-up lost delay lead dual left turn and directional separation were 1.41 sec. and 3.27 sec., respectively, showing the great difference. Therefore, different start-up lost delay according to changing type should be applied.

• Journal of the Korea Society for Simulation
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• v.24 no.3
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• pp.17-26
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• 2015

A cluster tool used in many kinds of semiconductor processes for improving the performance and the quality of wafers has a simple configuration, but its schedule is not easy because of its parallel processing module, a lack of intermediate buffers, and time constraints. While there have been many studies on its schedule, most of them have focused on full cycles in which identical work cycles are repeated under constant task times. In this research, we suggest strategies of start-up transient scheduling which satisfies time constraints and converges into a desirable steady schedule for full work cycle. The proposed schedules are expected robust under the stationary stochastic task times. Finally, we show that the strategies make schedules enters the desirable steady schedule and robust using the simulation.

• Korean Journal of Applied Biomechanics
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• v.31 no.1
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• pp.37-43
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• 2021

Objective: The purpose of this study was to investigate the effect of mobile phone text messaging on the collision avoidance strategy for an approaching and stationary pedestrian. Method: Eighteen healthy young adults participated in this study. Each participant was asked to perform a task to walking with/without mobile phone text messaging and a task to avoid collisions with another pedestrian who was approaching or stationary during walking. Results: When text messaging with avoidance collision, it showed an early onset time, a larger mediolateral COM trajectory, trunk rotation angle and trunk rotation velocity (p<.05). Also, compared to an approaching pedestrian, when avoiding collision with a stationary pedestrian, it showed a later onset time, a lager avoidance displacement, mediolateral COM trajectory, trunk rotation angle (p<.05). Conclusion: Results suggest that mobile phone text messaging while collision avoidance leads to delay the perception stage and alters the adaptation stage. Consequently, pedestrian executed in an exaggerated avoidance action to create a greater safety margin when attending to mobile phone test messages while avoiding another pedestrian.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.6
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• pp.495-500
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• 2003

To establish the dual-purpose barley cultivation for forage by clipping before overwintering and grain next year, an experiment was conducted to clarify the effect of clipping times and cultivars haying different winter habits in rice-barley cropping system at paddy field in southern Korea. Barley showed more forage yield by clipping once only on December 10 than that of twice-clipping on November 10 and December 10. Among experimented cultivars, Saegangbori (winter habit II) and Keunalbori (winter habit IV) produced higher forage yield in one time clipping than the others. On the contrary, higher total digestive nutrients(TDN) was gained from twice-cut plants. Barley clipped once or twice headed and matured without serious delay as compared to the conventionally sown barley. In spite of clipping in November and/or December, barley produced grain yield similar to that of the conventional. Conclusively, it was regarded that cultivars having II-III winter habit were suitable for dual-purpose barley cultivation for forage in winter season and grain harvest next year.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.618-636
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• 1997

DQDB(Distributed Queue Dual Bus) protocol, the IEEE 802.6 standard protocol for metropolitan area networks, does not fully take advantage of the capabilities of dual bus architecture. Although fairness in bandwidth distribution among nodes is improved when using so called the bandwidth balancing mechanism, the protocol requires a considerable amount of time to adjust to changes in the network load. Additionally, the bandwidth balancing mechanism leaves a portion of the available bandwidth unused. In a high-speed backbone network, each node may act as a bridge/ router which connects several LANs as well as hosts. However, Because the existence of high speed LANs becomes commonplace, the congestionmay occur on a node because of the limitation on access rate to the backbone network and on available buffer spaces. to release the congestion, it is desirable to install some congestion control algorithm in the node. In this paper, we propose an efficient congestion control mechanism and fair and waster-free MAC protocol for dual bus network. In this protocol, all the buffers in the network can be shared in such a way that the transmission rate of each node can be set proportional to its load. In other words, a heavily loaded node obtains a larger bandwidth to send the sements so tht the congestion can be avoided while the uncongested nodes slow down their transmission rate and store the incoming segments into thier buffers. this implies that the buffers on the network can be shared dynamically. Simulation results show that the proposed probotol significantly reduces the segment queueing delay of a heavily loaded node and segment loss rate when compared with original DQDB. And it enables an attractive high throughput in the backbone network. Because in the proposed protocol, each node does not send a requet by the segment but send a request one time in the meaning of having segments, the frequency of sending requests is very low in the proposed protocol. so the proposed protocol signigificantly reduces the segment queuing dely. and In the proposed protocol, each node uses bandwidth in proportion to its load. so In case of limitation of available buffer spaces, the proposed protocol reduces segment loss rate of a heavily loaded node. Bandwidth balancing DQDB requires the wastage of bandwidth to be fair bandwidth allocation. But the proposed DQDB MAC protocol enables fair bandwidth without wasting bandwidth by using bandwidth one after another among active nodes.