• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.281-283
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• 2016

Recently, many industrial instruments face the problem of protocol compatibility with the external monitoring and control system. This paper is prepared in the main control board to support the industrial communication protocol conversion, control, and monitoring. The industrial communication gateway module is also designed to ensure that the protocol conversion of CAN bus and Ethernet. The main board processor is used the Atmega2560, and placed 4ea RS485 serial slots for sub-board. One of them is used for communication CAN bus and Ethernet. It provides analog and digital I / O through each of the slots is used for control and monitoring.

• The Transactions of the Korea Information Processing Society
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• v.5 no.10
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• pp.2654-2662
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• 1998

Maximum single bus throughput of standard IEEE 802.6 DQDB(Distributed Queue Dual Bus) is not obtained over 1. Therefore, lots of studies for improving bus throughput have done by QA slot preuse/reuse. We propose three calculation cethods for network's utilization with preuse/reuse scheme based on erasure nodes. One is calculation method by traffic density function, other is calculation method for obtaining maximum throughput. The other is calculation method using probability concept which follows real DQDB operation mechanisms. The calculated throughputs are compared with each others. The results shows some favorite phenomena. The proposed calculation methods can be casily expanded in mumber of nodes or in number of erasure nodes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.1
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• pp.75-80
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• 2009

Bum-in test is one for eliminating semiconductor devices that are subject to early failures and other operational problems; it is usually carried out on the devices by imposing severe test conditions such as elevated voltages, temperatures, and time. In order for such a test to be performed, each burn-in board having devices to be tested, needs to be inserted into a corresponding slot. A set of such slots is called a zone. The slots comprising a zone can only have the burn-in boards with the devices of the same type. In order to test many different types of semiconductor devices, it is desirable to build a burn-in test system to have as many zones as possible. A zone controller controlling a zone, is a device that performs a burn-in test and collects test results. In case of existing systems, each zone controller takes care of a zone that consists of a fixed number of slots. Since a zone controller is, in most cases, embedded into a workstation that controls the overall testing process, adding new zone controllers is restricted by the spaces for them. As a way to solve or alleviate these problems, a dynamic zone system in which the number of slots in a zone can be dynamically allocated, is presented. This system maximizes the efficiency of system utilization, by altering the number of slots and hence minimizing the idle slots of a zone. In addition, all the test operations being performed must be aborted for maintenance in existing systems. In dynamic zone systems, however, a separate and independent maintenance is allowed for each slot, as long as the main power supply system has no problem.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.96-103
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• 2000

The voice traffic is one of the most important real-time objects in WATM(Wireless Asynchronous Transfer Mode) networks. In this paper, we propose a new MAC(Medium Access'Control) protocol for the efficienttransmission of voice traffic over WATM networks in the multimedia environment and compare the performanceto existing similar protocols. The new protocol separates the reservation slot period for voice and that for data toguarantee some level of QoS(Quality of Service) in voice traffic. This is denoted by a slot assignment functiondepending on the frame size. According to the characteristics of voice traffic which is repeatedly in silent states,the protocol allocates voice reservation request slots dynamically with respect to the number of silent(off state)voice sources and also sends the first block of talkspurt restarted after silent period with a reservation requestslot to reduce the access delay.The simulation results show that the proposed protocol has better performance than Slotted Aloha in bandwidthefficiency, and can serve a certain level of QoS by the given slot assignment function even when the number ofvoice terminals varies dynamically. This means we can observe that the new MAC protocol is much better thanthe NC-PRMA(None Collision-Packet Reservation Multiple Access) protocol.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.4
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• pp.894-900
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• 2004

There are many types of circularly polarized(CP) microstrip antenna elements, which are used as a good unit radiator. Since an advantage of CP antenna is no strict alignment requirements between Rx and Tx system, the printed antennas with circular polarization are very often used in numerous satellite and mobile radio systems. In order to realize the broad bandwidth of 3 dB axial ratio and impedance of CP microstrip antenna, complex feed structure and tri-plate patch element have been researched. This paper describes a design of wideband microstrip cross slot array antennas with circular polarization. The proposed antenna is composed of an open-ended microstrip feed line as a feeder and a cross slot as a radiator for circular polarization. To realize the wide bandwidth, tri-plate structure are considered and cross slot is electromagnetically coupled with feed line. Optimum parameters of 1-element cross slot antenna are analyzed and designed by method of moments. These parameters are also applied to may antennas design considered the mutual coupling between radiating elements. Right hand circular polarization(RHCP) and left hand circular polarization(LHCP) of the proposed antenna are easily controlled by asymmetrical cross slot structure and slot position. In 1-element and 15-element cross slot array antenna, the good axial ratio of 1 dB below and the broad bandwidth characteristics of antenna are obtained.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.6
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• pp.1241-1246
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• 2005

This paper proposes an adaptive multislot allocation algorithm in order to achieve larger system capacity and higher throughput data transmissions. The proposed system is the combination of the slow adaptive modulation system, in which the base station dynamically assigns optimum modulation parameters measuring the SNR of each transmission terminal, and the multislot allocation scheme, in which the base station flexibly allocates an appropriate number of TDMA data slots according to the instantaneous load conditions. Computer simulations confirm that the proposed system can tremendously improve average message delay characteristics in comparison with the conventional fixed slot allocation method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.117-120
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• 2001

In this paper, a contention-based reservation MAC protocol is proposed for non-real-time bursty traffic services in the wireless ATM networks. In order to reduce the collisions of the reservation request packets, the base station scheduler calculates the transmission probability using the number of RAS minislots and the estimated load of the reservation request packets. And it broadcasts the calculated transmission probability through the downlink control channel. Mobile terminals, which have a traffic burst, select randomly a RAS minislot and transmit the reservation request packet with the received transmission probability. The reservation request packet contains the number of packets in the buffer. The base station allocates slots based on the buffer status of the received reservation request packets.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.6
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• pp.1435-1440
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• 2014

Nodes in WSNs must operate under limited energy resource. Controlling access to the channel in WSNs plays a key role in determining channel utilization and energy consumption. This paper introduces a priority-based time slot allocation protocol for hybrid TDMA/CSMA MAC in WSNs. This protocol combines both TDMA and CSMA techniques while introducing prioritization by (m,k)-firm constraint. The performance of this protocol is obtained through simulations for various number of nodes and show significant improvements in delay and packet delivery ratio compared to S-MAC.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.3
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• pp.140-149
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• 2002

This paper describes the characteristics of beam-tilting slot away waveguide antennas for mobile DBS reception. As a basic study of slotted waveguide array, design for 16 slot elements located on a broad-wall waveguide is considered. Design parameters such as slot length, space between each slot and cross slot angle of antennas with the beam-tilting characteristics are calculated by method of moments. Based on these results, the radiation waveguide antennas with 16-element $\times$16-array are designed and fabricated. The measured main beam direction angles of the fabricated antennas are 48$^{\circ}$to 50$^{\circ}$depending on the measured frequencies and it shows good agreement with prediction. The measured 3 dB beam width of elevation pattern is about 13$^{\circ}$, and the axial ratio and the gain measured at DBS band are observed 2.8 dB below and 24 dBi above, respectively. In order to evaluate a performance of the fabricated waveguide planar antenna, it is combined with the satellite tracking control system and the field performance test of antenna mounted on a mobile vehicle is carried out at highway. During the measurement, it was possible to watch television without a break signal in a driving vehicle and an excellent performance of the proposed antennas was demonstrated.

• Journal of Aerospace System Engineering
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• v.13 no.4
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• pp.50-59
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• 2019

The design of the main control valve, which is the main component of the flap control system, was based on actual manufacturing experience on the basis of trial and error method. In this paper, a model-based part design method is proosed. The flap control system consists of a main control valve, fail-safe valve, solenoid valve, LVDT and force motor. The main control valve consists mainly of a spool and slot. The important design parameters of the main control valve are the slot width, overlap and clearance. AMESim is linked to the model and it analyzes the flow path of the main control valve. Applying the proposed design procedure, it was confirmed that the required performance was satisfied within the allowable machining error range.