• Transactions on Electrical and Electronic Materials
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• v.18 no.4
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• pp.229-236
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• 2017

This paper deals with the design and implementation of an efficient topology for cascaded multilevel inverters with reduced part counts. In the proposed design, a well-established basic unit is first developed. The series extension of this unit results in the formation of the proposed multilevel inverter. The proposed design minimizes the number of power electronic components including insulated-gate bipolar transistors and gate driver circuits, which in turn cuts down the size of the inverter assembly and reduces the operating power losses. An explicit control strategy with enhanced device efficiency is also acquired. Thus, the part count reductions enhance not only the economical merits but also the technical features of the entire system. In order to accomplish the desired operational aspects, three algorithms are considered to determine the magnitudes of the dc voltage sources effectively. The proposed topology is compared with the conventional cascaded H-bridge multilevel inverter topology, to reflect the merits of the presented structure. In continue, both the analytical and experimental results of a cascaded 31-level structure are analyzed. The obtained results are discussed in depth, and the exemplary performance of the proposed structure is corroborated.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.365-370
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• 2004

The integration of intelligent devices, devices-level networks, and software into motor control systems can deliver improved diagnostics, fast warnings for increased system reliability, design flexibility, and simplified wiring. Remote access to motor-control information also affords an opportunity for reduced exposure to hazardous voltage and improved personnel safety during startup and trouble-shooting. This paper presents LonWorks fieldbus networked intelligent induction control system architecture. Experimental bed system with two inverter motor driving system for controlling 1.5kW induction motor is configured for LonWorks networked intelligent motor control. In recent years, MCCs have evolved to include component technologies, such as variable-speed drives, solid-state starters, and electronic overload relays. Integration was accomplished through hardwiring to a programmable logic controller (PLC) or distributed control system (DCS). Devicelevel communication networks brought new possibilities for advanced monitoring, control and diagnostics. This LonWorks network offered the opportunity for greatly simplified wiring, eliminating the bundles of control interwiring and corresponding complex interwiring diagrams. An intelligent MCC connected in device level control network proves users with significant new information for preventing or minimizing downtime. This information includes warnings of abnormal operation, identification of trip causes, automated logging of events, and electronic documentation. In order to show the application of the multi-motors control system, the prototype control system is implemented. This paper is the first step to drive multi-motors with serial communication which can satisfy the real time operation using LonWorks network.

• Journal of Korean society of Dental Hygiene
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• v.15 no.3
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• pp.363-369
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• 2015

Objectives: The purpose of this study is to investigate the cognition and practice of infection control in the dental hygienists. Methods: A self-reported questionnaire was completed by 220 dental hygienists in Busan and Gyeongnam from August 1 to 31, 2014. The questionnaire was adapted from Nam. The questionnaire consisted of four questions of the general characteristics of the subjects, two questions of infection control factors, four questions of clinic environment, 50 questions of awareness of infection control, and 50 questions of infection control practice. Cronbach's alpha in the awareness of infection control was 0.958 and that in infection control practice was 0.950. Results: The dental hygienists in the large scale hospitals tended to have higher score of cognition and practice of infection control thatn those in the small scale hospitals(p<0.001). Small scale hospitals tended to have lower infection rate than the large scale hospitals. The education for the infection control guideline reduced the infection prevalence rate. Conclusions: In order to reduce the infection prevalence rate, it is necessary to educate the dental hygienists continuously and to provide the infection control guideline to the dental clinics.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.1
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• pp.45-55
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• 1998

In this paper, a robust path tracker and depth controller of Autonomous Underwater Vehicle based on sliding mode control is presented. We have also designed augmented equivalent control inputs by analyzing the sliding mode with the reaching mode. This can enhance the reaching rate, and improve chattering problems, that is, noise caused by the control plane actuator of the vehicle, which is one of the problems that occur when sliding mode control is used. Also to resolve the steady state error generated in the path tracker under current effect, a modified sliding plane is constructed. Also a redesigned sliding plane and control input using transformation matrix is proposed to do easy design of MIMO depth controller. For state variables that cannot be measured directly, reduced order sliding mode control is used to design an observer. The performance of designed path tracker and depth controller is investigated by computer simulation. The results show that the proposed control system has robust performance to parameter variation, modelling error and disturbance.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1298-1307
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• 2017

The constant on-time current-mode controlled (COT-CMC) switching dc-dc converter is stable, with no subharmonic oscillation in its current loop when a voltage ripple in its outer voltage loop is ignored. However, when its output capacitance is small or its feedback gain is high, subharmonic oscillation may occur in a COT-CMC buck converter with a proportional-integral (PI) compensator. To investigate the subharmonic instability of COT-CMC buck converters with a PI compensator, an accurate reduced-order asynchronous-switching map model of a COT-CMC buck converter with a PI compensator is established. Based on this, the instability behaviors caused by output capacitance and feedback gain are investigated. Furthermore, an approximate instability condition is obtained and design-oriented stability boundaries in different circuit parameter spaces are yielded. The analysis results show that the instability of COT-CMC buck converters with a PI compensator is mainly affected by the output capacitance, output capacitor equivalent series resistance (ESR), feedback gain, current-sensing gain and constant on-time. The study results of this paper are helpful for the circuit parameter design of COT-CMC switching dc-dc converters. Experimental results are provided to verify the analysis results.

• Journal of Biosystems Engineering
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• v.37 no.3
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• pp.148-154
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• 2012

Purpose: In order to improve road-friendliness of heavy vehicles, a fuzzy hybrid control strategy consisting of a hybrid control strategy and a fuzzy logic control module is proposed. The performance of the proposed strategy should be effectively evaluated using a hardware-in-the-loop (HIL) simulation model of a semi-active suspension system based on the fuzzy hybrid control strategy prior to real vehicle implementations. Methods: A hardware-in-the-loop (HIL) simulation system was synthesized by utilizing a self-developed electronic control unit (ECU), a PCI-1711 multi-functional data acquisition board as well as the previously developed quarter-car simulation model. Road-friendliness of a semi-active suspension system controlled by the proposed control strategy was simulated via the HIL system using Dynamic Load Coefficient (DLC) and Dynamic Load Stress Factor (DLSF) criteria. Results: Compared to a passive suspension, a semi-active suspension system based on the fuzzy hybrid control strategy reduced the DLC and DLSF values. Conclusions: The proposed control strategy of semi-active suspension systems can be employed to improve road-friendliness of road vehicles.

• Earthquakes and Structures
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• v.10 no.5
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• pp.1067-1087
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• 2016

In this paper, a decoupled proportional-integral-derivative (PID) control approach for seismic control of smart structures is presented. First, the state space equation of a structure is transformed into modal coordinates and parameters of the modal PID control are separately designed in a reduced modal space. Then, the feedback gain matrix of the controller is obtained based on the contribution of modal responses to the structural responses. The performance of the controller is investigated to adjust control force of piezoelectric friction dampers (PFDs) in a benchmark base isolated building. In order to tune the modal feedback gain of the controller, a suitable trade-off among the conflicting objectives, i.e., the reduction of maximum modal base displacement and the maximum modal floor acceleration of the smart base isolated structure, as well as the maximum modal control force, is created using a multi-objective cuckoo search (MOCS) algorithm. In terms of reduction of maximum base displacement and story acceleration, numerical simulations show that the proposed method performs better than other reported controllers in the literature. Moreover, simulation results show that the PFDs are able to efficiently dissipate the input excitation energy and reduce the damage energy of the structure. Overall, the proposed control strategy provides a simple strategy to tune the control forces and reduces the number of sensors of the control system to the number of controlled stories.

• Quality Improvement in Health Care
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• v.19 no.1
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• pp.30-42
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• 2013

Objectives: This study was intended to check if the "Creating Clean Wards" project, which is an innovative reinforced campaign activity targeting infection control strategies and active surveillance cultures for VRE (vancomycin resistant enterococci) high-risk patients to be admitted in the NS (neuro-surgery) wards, would be reduced the incidence rates of VRE acquisition, transmission rates. Methods: 75 subjects of the VRE high-risk patients were surveyed by carrying out active surveillance cultures of VRE colonization 11 times from January to March, 2012. And the retrospective study was conducted dividing them into two groups. Results: The incidence rates of VRE acquisition was reduced to 3.67 cases per 1,000 patients day in the control group and to 2.88 cases in experimental group, which was not statistically significant (p = .753). VRE transmission rates of 0.0015 per day before the project tended to increase to 0.0019, although not statistically significant (p = .650). As a result of multivariate analysis with regard to using glycopeptide antibiotics in order to find out risk factors of VRE colonization, the patients who had been treated with glycopeptide until VRE colonization showed 274.41 times higher rate. Conclusion : For effective VRE infection control in NS wards, We should carry out active surveillance culture regularly, especially patient of using glycopeptide. And block the spread of VRE by strengthening infection control through the strict isolation and the changed mind-set of members motivated by the "Creating Clean Wards" campaign.

• Journal of Korean Academy of Nursing Administration
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• v.20 no.1
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• pp.117-127
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• 2014

Purpose: In order to provide a systematic and standardized treatment course for MVD patients, a critical pathway (CP) program was developed and the results of its long term application were analyzed. Methods: This was a methodological study. The CP was established and applied to 75 (step I) and 1,216 (step II). Another group of 56 with similar features was used as a control group. Results: The application of CP turned out to be useful in many regards: the rate of hearing loss was reduced from 1.8% to 0% (step I) and 0.5% (step II), and low cranial nerve palsy was reduced from 1.8% to 1.3% and 0.7%, respectively. The length of hospitalization decreased by 2.56 days (25.2%) for step I and 3.05 days (30.0%) for step II. Days of ICU stay were reduced by 7.9% and 1.8%. The total cost per patient was reduced by 14.8% (step I). The cost per day was increased by 13.7% and 52.4%. An increase in the patient satisfaction index was noted, as shown in the ICU information guide (p=.002). Conclusion: The development and application of CP was found to improve the quality of medical treatment and the efficacy of hospital management in MVD patients. Well organized and efficient system and multidisciplinary teamwork are the key component of the successful application of CP.

• Korean Journal of Health Education and Promotion
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• v.15 no.2
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• pp.119-142
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• 1998

The purpose of this article is to provide a method of losing weight and early managing risky factors of geriatric diseases by having male and female obese middle school students' participate in behavioral modification and aerobic exercise, foster their own desirable behavioral habit and confidence in solving obesity and continue their living pattern all their life. In order to do this, 64, subjects over 20% obese degree obtained using the standard weight, belonging within 50% range of weight percentage per height(male:32, female:32) were grouped to 4 categories of aerobic exercise therapy, behavioral modification therapy, both therapies combinedly applied and control ones by 8 male and female students allocated to each group respectively, and they were practiced to each program for 12 weeks, and the findings between group were obtained as follows. 1. The male and female middle school students' cholesterol amount of blood fat reduced most in the combinedly performed group of aerobic exercise and behavioral modification therapy. It indicated a statistically significant difference between groups (F(3,56) =9.50, p=.000) and the measurements according to the application period of program as well (F(3,168)=554.94, p=.000). The cholesterol amount per measurement period reduced most between 8 and 12 weeks. 2. The male and female middle school students' high density fat amount increased most in the combinedly performed group of aerobic exercise therapy and behavioral therapy, its descending order of next highest rate was aerobic exercise therapy, behavioral modification therapy and control group. It indicated a statistically significant difference between the distinction of male and female sexes (F(1.56)=13.82. p=.000) and the measurements according to the application period of program (F(3,168) =55.58, p=.000). The high density fatty Quality per measurement period increased most between 8 and 12 weeks. 3. The male and female middle school students' low density fat amount reduced most in the combinedly performed group of aerobic exercise therapy and behavioral modification therapy. It indicated a statistically significant difference between groups (F(3,56)=17.35, p=.000) and the measurements according to the application period of program (F(3,168)=891.14, p=.000. The low density fat amount reduced most between 8 and 12 weeks. 4. The male and female middle school students' neutral fat amount reduced most in the combinedly performed group of aerobic exercise therapy and behavioral modification therapy. It indicated a statistically significant difference between the distinction of sexes (F(1,56)=9.54, p=.003) and groups (F(3,56) =25.57, p=.000) and the measurements according to the application period of program (F(3,168) =566.03, p=.000). The male students indicated the most reduction between 4 and 8 weeks. while the female students between 8 and 12 weeks.