• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.288-291
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• 1999

The PID (Proportional-Integral-Derivative) controller is widely used in the industries for more than fifty years with the well known Ziegler-Nichols tuning method and others varieties. However, most of the PID controller being used in the real practice still require trial and error adjustment for each process after the tuning method is done, which is consuming of time and needs the operator experiences to obtain the best results for the controller parameter. In order to reduce the inconvenience in the controller tuning, this paper presents a design of an automatic PID controller parameter analyzer being used as a support instrument in the industrial process control. This analyzer is designed based on the tuning formula of Dahlin to synthesize the PID controller parameter. Using this analyzer, the time to be spent in the trial and error procedures and its complexity can be neglected. Experimental results using PID controller parameter synthesized from this analyzer to the liquid level control plant model and the fluid flow control plant model show that the responses of the controlled systems can be efficiently controlled without any difficulty in mathemathical computation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4A
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• pp.380-387
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• 2011

While mobile IPTV services are supported through the mobile WiMAX networks, there must need some guaranteed bandwidth for the IPTV services especially if IPTV and non-IPTV services are simultaneously supported by the mobile WiMAX networks. The quality of an IPTV service definitely depends on the allocated bandwidth for that channel. However, due to the high quality IPTV services and to support of huge non-IPTV traffic over mobile WiMAX networks, it is not possible to guarantee the sufficient amount of the limited mobile WiMAX bandwidth for the mobile IPTV services every time. A Service Level Agreement (SLA) between the mobile IPTV service provider and mobile WiMAX network operator to reserve sufficient bandwidth for the IPTV calls can increase the satisfaction level of the mobile IPTV users. In this paper, we propose a SLA negotiation procedure for mobile IPTV users over mobile WiMAX networks. The Bandwidth Broker controls the allocated bandwidth for IPTV and non-IPTV users. The proposed dynamically reserved bandwidth for the IPTV services increases the IPTV user's satisfaction level. The simulation results state that, our proposed scheme is able to provide better user satisfaction level for the IPTV users.

• Journal of the Korea Society of Computer and Information
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• v.22 no.10
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• pp.109-119
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• 2017

In recent through development of IOT owing to that mass stream data is being generated in variety of application complex event processing technology is being watched with keen interest as a technology to analyze this kind of real-time continuous data. However, the existing study related with complex event processing only comes to an end at simple event processing based on low-level event or comes to an end at service defect discovery with providing limited operator and so on. Accordingly, there would be limitation to provide useful analysis information. In this paper in consideration of complex event along with aspect-oriented programming an extended complex event model is provided, which is possible to provide more valuable and useful information. Specifically, we extend the model to support hierarchical event structures and let the model recognize point-cuts of aspect-oriented programming as events. We provide the event operators designed to specify the events on instances and handle temporal relations of the instances. It is presented that syntax and semantics of constructs in our event processing language including various and progressive event operators, complex event pattern, etc. In addition, an event context mechanism is proposed to analyze more delicate events. Finally, through application studies application possibility of this study would be shown and merits of this event model would be present through comparison with other event model.

• Hwankyungkyoyuk
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• v.12 no.1
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• pp.335-347
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• 1999

Restricted by time and space, formal environmental education has a limit in accommodating fast changing socal phenomena and quickly spreading environmental problems. Therefore, to carry out more efficiently the environmental education for middle and high school students, this study is intended to search for a way to establish a network of formal and nonformal environmental education. More than 80% of civil environmental organizations replied they agree to establish a network of environmental education. As for the establishment of a network, they preferred the establishment in which middle and high school, civil environmental organizations, government, the environment-related departments of the universities. They preferred ‘civil environmental organizations’ for the operator, ‘local municipal or provincial level for the scale, ‘direct personal relations’ for the interchange method. To establish a network, they replied that ‘funding’, ‘specialists in environmental education’, ‘staff to proceed educations’, ‘reform of law and systems’ are required. They also preferred ‘funding from government budget’ for a way to fund a network. We can draw the following conclusions from the survey, We need a training program for environmental education staff not to make those educational programs by civil environmental organizations temporary Also, more studies should be done to establish more organized network of environmental education and nonformal environmental education by civil environmental organizations. Environmental problem varies depending on the local characteristics, and thus environmental education should be carried out locally at the network center for environmental education. Besides, local self-governing bodies should support it administratively and financially.

• Journal of the Ergonomics Society of Korea
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• v.32 no.4
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• pp.371-380
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• 2013

Objective: The aim of this study is to investigate the effects of design parameters of vibrotactile signals on semantic association with transmitted information conveying different meanings. Background: As information communication relying on human visual channel becomes excessive, the utility of vibrotactile signals is being interested as a substitute measure of delivering information. Properly designed hapticons may relieve burden of visual communication by rendering distinct and meaningfully compatible haptic sensations. Method: A typical Kansei engineering approach was adopted in this study. Ten most distinctive hapticons were selected among those having different frequencies and amplitudes. Associations between the hapticons and twenty four pairs of adjectives used to describe the state of automobile in control were gathered from thirty subjects using semantic differential scales. Results: The selected pairs of adjectives were summarized by factor analysis into two semantic dimensions named 'Awareness' and 'Directionality'. The experimental hapticons matched with the semantic dimensions were presented as a haptic emotion map. Conclusion: The results from this study support that frequencies and amplitudes of haptic signals play important roles in arousing different human perceptions regarding the two haptic emotional dimensions. Application: Properly designed hapticons with respect to the contents of transmitted information will increase human operator's situation awareness as well as system performance. The result from this study can be used to develop standardized hapticons for active haptic communication.

• Transactions on Control, Automation and Systems Engineering
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• v.3 no.1
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• pp.10-14
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• 2001

We studied the use of time-related information, with and without prediction, to support human operators performing moni-toring and control tasks in the process. Based on monitoring and control techniques used for Project Management we developed a display design for the process industries. A simulated power plant was used to test the hypothesis that availability of predictions along with information on past trends can improve the performances of the human operator handling faults. Several designs of dis-plays were tested in the experiment in which human operators had to detect and handle two types of faults(local and systems wide) in the simulated electricity generation process. Analysis of the results revealed that temporal data, with and without prediction, signifi-cantly reduced response time. Our results encourage the integration of temporal information and prediction in displays used for the control processes to enhance the capabilities of the human operators. Based on the analysis we proposed some guidelines for the de-signer of the human interface of a process control system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.142-143
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• 2017

As weapons systems are fused with advanced technologies, many of the expenses for research and development are favorites, and that group demands high reliability of weapons systems before the lifecycle. However, empirical studies on the reliability of defense weapons systems are restricted to lack of attention and limitation of data. In this research, we proposed the process of collecting field operation specifications based on the experience gathered by visiting directly to the weapons system operator's trap, strategy and maintenance support force (COMROKFLT, Naval Logistics Command, Naval Shipyard, production company). We used this to derive the operation MTBF of the solubility inducing bullet shooting system and compared it with the target value at the time of development.

• Journal of Communications and Networks
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• v.6 no.1
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• pp.68-77
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• 2004

In the near future packet networks should support applications which can not predict their traffic requirements in advance, but still have tight quality of service requirements, e.g., guaranteed bandwidth, jitter, and packet loss. These dynamic characteristics mean that the sources can be made to modify their data transfer rates according to network conditions. Depending on the customer&; needs, network operator can differentiate incoming connections and handle those in the buffers and the interfaces in different ways. In this paper, dynamic QoS-aware scheduling algorithm is presented and investigated in the single node case. The purpose of the algorithm is in addition to fair resource sharing to different types of traffic classes with different priorities ?to maximize revenue of the service provider. It is derived from the linear type of revenue target function, and closed form globally optimal formula is presented. The method is computationally inexpensive, while still producing maximal revenue. Due to the simplicity of the algorithm, it can operate in the highly nonstationary environments. In addition, it is nonparametric and deterministic in the sense that it uses only the information about the number of users and their traffic classes, not about call density functions or duration distributions. Also, Call Admission Control (CAC) mechanism is used by hypothesis testing.

• Journal of the Korean Society of Safety
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• v.29 no.1
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• pp.86-92
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• 2014

This paper provides an integrated view on human and system interaction in advanced and automated systems, which adopting computerized multi-functional artifacts and complicated organizations, such as nuclear power plants, chemical plants, steel and semi-conduct manufacturing system. As current systems have advanced with various automated equipments but human operators from various organizations are involved in the systems, system safety still remains uncertain. Especially, a human operator plays an important role at the time of critical conditions that can lead to catastrophic accidents. The knowledge on human error helps a risk manager as well as a designer to create and control a more credible system. Several human error theories were reviewed and adopted for forming the integrated perspective: gulf of execution and evaluation; risk homeostasis; the ironies of automation; trust in automation; design affordance; distributed cognition; situation awareness; and plan delegation theory. The integrated perspective embraces human error theories within three levels of human-system interactions such as affordance level, psychological logic level and trust level. This paper argued that risk management process should dealt with human errors by providing (1) reasoning improvement; (2) support to situation awareness of operators; and (3) continuous monitoring on harmonization of human system interaction. This approach may help people to understand risk of human-system interaction failure characteristics and their countermeasures.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.237-241
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• 2008

Femtocells are cellular access points that connect to a mobile operator's network using residential DSL or cable broadband connections. They have been developed to work with a range of different cellular standards including CDMA, GSM and UMTS. Like legacy base station, the frequency accuracy and phase alignment is necessary for ensuring the quality of service (QoS) for applications such as voice, real-time video, wireless hand-off, and data over a converged access medium at the femtocell. But, the GPS has some problem to be used at the femtocell, because it is difficult to set-up, depends on the satellite condition, and very expensive. So, some techniques are discussed to alternate with the legacy GPS system. NTP, PTP, Synchronous Ethernet use the ethernet to synchronize distributed clocks in packet networks. AGPS support reliable position information than the legacy GPS in poor signal conditions. But, These method also have some problems. So, hybrid timing method like A-GPS+PTP and TV+GPS was developed to make up the weak point of GPS. This paper introduces the each method and compare each other and y propose much better solution for timing synchronization at the Femtocell