• 한국산업융합학회 논문집
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• 제20권3호
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• pp.205-212
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• 2017

This paper focuses on worst-case delay analysis of the time-triggered IEEE 802.15.4 protocol to satisfy the industrial quality-of-service (QoS) performance. The IEEE 802.15.4 protocol is considered to be unsuitable for industrial networks because its medium access control method is contention-based CSMA/CA, which exhibits unstable performance with an unbounded delay distribution under heavy traffic. To avoid these limitations, this paper presents a time-triggered version of the nonbeacon-enabled network of IEEE 802.15.4 that relies on a time division multiplexing access (TDMA) method implemented in the application layer without any modification of specification. The timing analysis of this time-triggered IEEE 802.15.4 was executed, and the worst-case transmission delay was calculated. Based on this analysis, the time-triggered IEEE 802.15.4 is a promising alternative for wireless industrial networking.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.358-360
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• 1997

The train control and monitoring system(TCMS) is an on board computer system in railway vehicles performing the control, supervisory and diagnostic functions of the complete train. This system replaces a lot of hardwired relays and minimizes the necessaries vehicle wiring thus increasing the reliability of the train. In this paper, we proposed a software design technique of TCMS using CASE tool (SAO+). The TCMS functions are implemented in software easily programmed, using a functional block, graphic programming language. We applied the compressor air module to a case study.

• International Journal of Control, Automation, and Systems
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• 제6권6호
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• pp.845-858
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• 2008

In this paper, we consider a terminal, linear control system with delay, subject to unknown but bounded disturbances. For this system, we consider the problem of constructing a worst-case optimal feedback control policy, which can be corrected at fixed, intermediate time instants. The policy should guarantee that for all admissible uncertainties the system states are in prescribed neighborhoods of predefined system states, at all fixed, intermediate time instants, and in the neighborhood of a given state at a terminal time instant, and the value of the cost function is the best guaranteed value. Simple explicit rules(which can be easily implemented on-line) for constructing the optimal control policy in the original control problem are derived.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권4호
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• pp.374-378
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• 2014

PID control method usually has problems of overshoot and oscillation in high order control system, therefore, it is important to improve the control method so as to reduce the overshoot and oscillation. Based on MATLAB simulation, a permanent magnet (PM) DC servomotor control system is studied in this paper. The motor is modeled according to the universal motor theory, and with the help of the fourth order Ronge-Kutta method, its speed control is simulated and compared between two different dual closed-loops PWM control methods. This case study helps undergraduate students to better understand theories related to electrical engineering, such as electrical machinery, power electronics and control theory, as well as digital solution of state equations.

• 대한기계학회논문집A
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• 제28권8호
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• pp.1152-1158
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• 2004

In this study a MRAC(model reference adaptive control) for fluid power elevator model system was designed. The MRAC was compared with PI control in case of applying to the elevator model system with constant external load and changing external load. In this case external load was produced by a single fluid power cylinder combined with pressure control valve. In conclusion the MRAC control performance was better than PI control performance because overshoot and steady state error of the elevator model system controlled by the MRAC were not appeared for constant and changing external load.

• Smart Structures and Systems
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• 제12권2호
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• pp.157-179
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• 2013

We present an approach, based on the state dependent Riccati equation, for designing non-collocated seismic response control strategies for buildings accounting for physical constraints, with particular attention to force saturation. We consider both cases of active control using general actuators and semi-active control using magnetorheological dampers. The formulation includes multi control devices, acceleration feedback and time delay compensation. In the active case, the proposed approach is a generalization of the classic linear quadratic regulator, while, in the semi-active case, it represents a novel generalization of the well-established modified clipped optimal approach. As discussed in the paper, the main advantage of the proposed approach with respect to existing strategies is that it allows to naturally handle a broad class of non-linearities as well as different types of control constraints, not limited to force saturation but also including, for instance, displacement limitations. Numerical results on a typical building benchmark problem demonstrate that these additional features are achieved with essentially the same control effectiveness of existing saturation control strategies.

• Parasites, Hosts and Diseases
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• 제51권5호
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• pp.557-562
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• 2013

In contrast to the gradual reduction in the number of locally transmitted malaria cases in China, the number of imported malaria cases has been increasing since 2008. Here, we report a case of a 39-year-old Chinese man who acquired Plasmodium ovale wallikeri infection while staying in Ghana, West Africa for 6 months in 2012. Microscopic examinations of Giemsa-stained thin and thick blood smears indicated Plasmodium vivax infection. However, the results of rapid diagnostic tests, which were conducted 3 times, were not in agreement with P. vivax. To further check the diagnosis, standard PCR analysis of the small-subunit rRNA gene was conducted, based on which a phylogeny tree was constructed. The results of gene sequencing indicated that this malaria is a variant of P. ovale (P. ovale wallikeri). The infection in this patient was not a new infection, but a relapse of the infection from the one that he had contracted in West Africa.

• 동의생리병리학회지
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• 제22권4호
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• pp.968-974
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• 2008

This study was aimed to investigate the electrolytes and its relationship with acute stroke patients in each stroke type by case-control study. 217 patients with first-ever acute stroke within 2 weeks as the case group(Cases), 146 people without four major risk factors(hypertension, diabetes mellitus, hyperlipidema and ischemic heart disease) as the healthy control group(Normals), and 160 people as the general control group(Controls) were recruited at the Stroke Medical Center in Daejeon University Oriental Medicine Hospital from july 2005 to march 2007 for this case-control study. We analyzed the odds ratio of electrolytes in binary logistic analysis and evaluated each stroke type and general characteristics such as age, sex etc. The level of sodium(Na+) and potassium(K+) were significantly lower in LAA, SVO type of ischemic stroke and hemorrhagic stroke. But the level of chloride(Cl-) had no significant relation with stroke occurance. In this study we demonstrated that low sodium(Na+) and potassium(K+) have an influence on stoke occurance than chloride(Cl-). And we think that the electrolytes must be considered in risk factors of ischemic stroke in Korean and more prospective studies are needed.

• 한국자동차공학회논문집
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• 제19권6호
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• pp.30-36
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• 2011

The current test methods are insufficient to evaluate and ensure the safety and reliability of vehicle system for all possible dynamic situation including the worst case such as rollover, spin-out and so on. Although the known NHTSA Sine with dwell steering maneuvers are applied for the vehicle performance assessment, they aren't enough to estimate other possible worst case scenarios. Therefore, it is crucial for us to verify the various worst cases including the existing severe steering maneuvers. This paper includes useful worst case based upon the existing worst case scenarios mentioned above and worst case evaluation for vehicle dynamic controller in simulation basis and UCC HILS. The only human steering angle is selected as a design parameter here and optimized to maximize the index function to be expressed in terms of both yaw rate and side slip angle. The obtained scenarios were enough to generate the worst case to meet NHTSA worst case definition. It has been concluded that the new procedure in this paper is adequate to create other feasible worst case scenarios for a vehicle dynamic control system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권1호
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• pp.98-115
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• 2012

New trend called ubiquitous leads the recent business by standardization and integration. It should be the main issue how to guarantee the integration and accountability on each business, especially in mission critical system which is mainly supported by M2M (Machine to Machine) control mechanism. This study is from the analysis of digital forensics case study that is from the M2M Sensing Control Mechanism problem of the "Imjin River" case in 2009, where a group of family is swept away to death by water due to M2M control error. The ubiquitous surroundings bring the changes in the field of criminal investigation to real time controls such as M2M systems. The needs of digital forensics on M2M control are increasing on every crime scene but we suffer from the lack of control metrics to get this done efficiently. The court asks for more accurately analyzed results accounting high quality product development design. Investigators in the crime scene need real-time analysis against the crime caused by poor quality of mission critical systems. It seems to be every need of Real-Time-Enterprise, so called ubiquitous society on the case. We try to find the efficiency and productivity in discovering non-functional design defects in M2M convergence products focusing on three metrics in study model with quick implementation. Digital forensics system in present status depends on know-how of each investigator and is hard to expect professional analysis on every field. This study set up a hypothesis "Co-working of professional investigators on each field will qualify Performance and Integrity" especially in mission critical system such as M2M and suggests "Online co-work analysis model" to efficiently detect and prevent mission critical errors in advance. At the conclusion, this study proved the statistical research that was surveyed by digital forensics specialists around M2M crime scene cases with quick implementation of dash board.