• Proceedings of the KSR Conference
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• 2011.10a
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• pp.724-730
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• 2011

A turnout serves to switch train from one line to another. The turnout consists of a Point which is switchs the rail to induce direction, and a Crossing which is cross over two line on the plane surface, and a Lead where is middle section in Point to Crossing. Point machine, consists of a turnout, is important facilities in railway signal, that is safety issue relates in derailment of the train. Recently, train delay and accident frequently occurred because of the turnout include in a point machine trouble of electrical and mechanical. So in order to prevent train accident the research is advanced, install of normal and reverse indication lamp in a point machine, development of adherence detector for sensing the status of adhesion between the stock rails and tongue rails etc. In this paper investigates the problem which is connected with a turnout trouble, include in a point machine, occurrence at the time of train accident, and then proposed to the safety system model in order to prevent the train accident in turnout.

• The Korean Journal of Ecology
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• v.15 no.4
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• pp.345-354
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• 1992

Allocation patterns of energy and mineral elements were investigated with phaseolus multiflorus grown in the environmental gradients. The result showed different energy allocation patterns according to relative light intensities and nutrients. The optimal switching time of energy allocation from vegetative to resproductive growth was delated as decreasing relative light intensity. The switch of the shift to reproduction was timed earlier in phosphorus treatment and delayed in nitrogen treatment. Analyzing the mineral elements to various organs, patterns of energy allocation were different from those of mineral allocation. There was no significant difference for allocation patterns in relative light intensity gradients. it was shown that n and p were distributed over the reproductive organs, k mainly in stems, ca in leaves and na in roots. mg was evenly distributed in each organs.

• ETRI Journal
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• v.34 no.4
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• pp.553-563
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• 2012

Serial peripheral interface (SPI) has been identified as a bottleneck in many wireless sensing systems today. SPI is used almost universally as the physical connection between the microcontroller unit (MCU) and radios, storage devices, and many types of sensors. Virtually all wireless sensor nodes today perform up to twice as many bus transactions as necessary to transfer a given piece of data, as an MCU must serve as the bus master in all transactions. To eliminate this bottleneck, we propose the master-handoff protocol. After the MCU initiates reading from the source slave device and writing to the sink slave device, the MCU as a master becomes a slave, and either the source or the sink slave becomes the temporary master. Experiment results show that this master-handoff technique not only cuts the data transfer time in half, but, more importantly, also enables a superlinear energy reduction.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.60-65
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• 2012

This paper deals with an CAE analysis and optimization of injection molding for a mobile phone cover. Two design goals are established in the optimization; one is to switch over the feed system from cold runner to hot runner for the purpose of reducing material costs, and the other is to minimize the warpage in order to improve product quality. By the full-factorial experiments for design parameters, we showed that the cold runner design could be changed to the hot runner design by replacing the current resin with a new resin of higher fluidity. In addition, we could significantly reduce the warpage of the cover product under the hot runner system by optimizing packing pressure and packing time.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.8
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• pp.40-48
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• 2015

In this paper, battery charging and discharging circuit with a single voltage power supply is proposed. The proposed circuit has the separated current path and charging-monitoring sequence control scheme. In the charging sequence, the proposed 2-level comparator combined with control signal of the micro-processor can control the constant charging current to protect the over current of the battery. Furthermore, the proposed circuit uses a periodic main power switch control to detect the discharging characteristics to estimate the approximated battery life-time. In the experiments, the proposed emergency power supply for emergency call system has 89% efficiency with 98% power factor. And the proposed sequence control scheme is well operated in the designed emergency power system.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.52-53
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• 2015

This paper introduces a novel hybrid converter combining a full-bridge soft switching converter and a full-bridge LLC converter. In this topology all the primary switches can achieve ZVS and ZCS all over the operation range. An additional switch and a diode are added in the secondary side of full-bridge converter to eliminate the circulating current and to provide a separate freewheeling path. The hybrid structure makes it possible to deliver the power to the secondary all the time of operation, thereby improving the efficiency. The proposed topology is suitable for the applications such as on-board chargers for electric vehicles and high power dc-dc converters. A 6.6-kW prototype converter was implemented and 97.5% efficiency was obtained through the experiments.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1251-1256
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• 2008

Urban railway system has make rapid progress ever since Seoul metro line No.1 was opened in 1974. Now, it is time to prepare system maintenance scheme and procedure that can be available even after 30 years from now. Especially, signaling system must be chosen with considering its life cycle since the system is categorized into electronic equipments. As for current signaling system, mechanical components such as relays has decreased while communication and S/W has integrated in order to implement its correct function. Therefore, it is required to establish system review and switch-over scheme with considering operational environment, maintenance system and an operator. In this paper, therefore, we analyzed various factors - technical, operational and economic - that have effect on system improvement so as to prevent making any mistakes on system improvement.

• ETRI Journal
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• v.45 no.3
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• pp.433-447
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• 2023

Critical issues such as connection congestion, long transmission delay, and packet loss become even worse during epidemic, disaster, and so on. In this study, a link load balancing method is proposed to address these issues on the data plane, a plane of the software-defined network (SDN) architecture. These problems are NP-complete, so a meta-heuristic approach, discrete particle swarm optimization, is used with a novel hybrid cost function. The superiority of the proposed method over existing methods in the literature is that it provides link and switch load balancing simultaneously. The goal is to choose a path that minimizes the connection load between the source and destination in multipath SDNs. Furthermore, the proposed work is dynamic, so selected paths are regularly updated. Simulation results prove that with the proposed method, streams reach the target with minimum time, no loss, low power consumption, and low memory usage.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.5
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• pp.219-231
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• 2005

Many applications in cluster computing require QoS (Quality of Service) services. Since performance predictability is essential to provide QoS service, underlying systems must provide predictable performance guarantees. One way to ensure such guarantees from network subsystems is to generate global schedules from applications'network requests and to execute the local portion of the schedules at each network interface. To ensure accurate execution of the schedules, it is essential that a global time base must be maintained by local clocks at each network interface. The task of providing a single time base is called a synchronization problem and this paper addresses the problem for system area networks. To solve the synchronization problem, FM-QoS (1) proposed a simple synchronization mechanism called FBS(Feedback-Based Synchronization) which uses built-in How control signals. This paper extends the basic notion of FM-QoS to a theoretical framework and generalizes it: 1) to identify a set of built-in network flow control signals for synchrony and to formalize it as a synchronizing schedule, and 2) to analyze the synchronization precision of FBS in terms of flow control parameters. Based on generalization, two application classes are studied for a single switch network and a multiple switch network. For each class, a synchroniring schedule is proposed and its bounded skew is analyzed. Unlike FM-QoS, the synchronizing schedule is proven to minimize the bounded skew value for a single switch network. To understand the analysis results in practical networks, skew values are obtained with flow control parameters of Myrinet-1280/SAN. We observed that the maximum bounded skew of FBS is 9.2 Usec or less over all our experiments. Based on this result, we came to a conclusion that FBS was a feasible synchronization mechanism in system area networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.1
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• pp.34-39
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• 2005

In this paper, we propose a new prioritized Optical Burst Switching (OBS) protocol based on a hop count, which can provide an efficient utilization in optical Wireless networks. Under several legacy schemes, a switch drops the burst with a shorter time among ones regardless of its traversed hop count. As a result, the dropped burst that have been traversed more hops might cause to waste bandwidth than the one traversed a few hops. Noting that this problem, we propose the Just Enough Time(JET) with a hop count scheme which can reduce the wasted bandwidth by prioritizing the burst traversed more hops over others. From the simulation result, we show that the proposed scheme is advantageous over the legacy schemes in terms of the burst blocking probability and the link utilization.