• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2030-2032
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• 1998

It is always necessary to high performance power supplies for the magnet system in the accelerator, especially when the number of power supplies are large. When have developed the compact power supply using switching technology instead of SCR phase control. We adopt the pulse width modulation(PWM) method with a half bridge DC/DC converter. In this way, we can make a compact system with light weight and small volume. Actual system we developed is 1.2kW, 35V/35A bipolar DC power supply current precision of +/-0.02%. It is possible to mount 10 unit in a conventional 19 rack. The built in controller has an RS422 protocol to drive 10 unit by one serial port up to 1.2km distance. If we adopt RS485 protocol, one serial port can control 32 power supplies. In this paper, we will report the design and performance of the prototype power supply.

• Journal of ILASS-Korea
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• v.5 no.3
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• pp.9-16
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• 2000

In a SI engine, three-way catalyst converter has the best efficiency when A/F ratio is near the stoichiometry. The feedback control using oxygen sensors in the commercial engine has limits caused by the system delays. So it is necessary to control fuel quantity in accordance with intake air amount in order to reduce exhaust emission and improve the specific fuel consumption. Precise A/F ratio control requires measurement of air amount with respect to the cylinder and injection fuel according to the air amount In this paper, we applied nonlinear fuel injection model and developed the algorithm of A/F ratio control. This algorithm includes the methods of measurement of transient air mass flowing into each cylinder, of calculation of injection pulse width for measured air mass, and the method of feedback and engine control by using lambda sensor. Also we developed control program for IBM-PC by using C++ Builder, and tested it in the commercial engine.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.615-619
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• 2009

There are many increasing demands for efficient high power density of auxiliary power unit(APU) for high speed traction application. Many techniques have been proposed to measure the voltage flicker on the traditional pulse width modulation(PWM) inverter. This paper proposes a novel functionality of the static inverter on the APU to mitigate the voltage flicker and regulate the output voltage. A new control algorithm for the inverter based on the Hilbert transform(HT) is presented. The HT is employed as an effective technique for tracking the voltage flicker levels in APU systems. Simulation results are provided to verify the tracking capabilities of the HT and to evaluate the performance of the proposed DG interface for multi-function operation.

• The Journal of the Korea Contents Association
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• v.11 no.8
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• pp.475-487
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• 2011

In this paper, we present a systematic method to derive spectrum of high-order pulse and a novel design of e-Learning system that deals with deriving the spectrum using concept-based branching method. Spectrum of high-order pulse can be derived using conventional methods including 'Consecutive Differentiations' or 'Convolutions', however, their complexity of calculation should be too high to be used as the order of the pulse increase. We develop a recursive algorithm according to the order of pulse, and then derive the formula of spectrum connected to the order with a newly designed look-up table. Moving along, we design an e-Learning content for studying the procedure of deriving high-order pulse spectrum described above. In this authoring, we use the concept-based object branching method including conventional page or title-type branching in sequential playing. We design all four Content-pages divided into 'Modeling', 'Impulse Response and Transfer Function', 'Parameters' and 'Look-up Table' by these conceptual objects. And modules and sub-modules are constructed hierarchically as conceptual elements from the Content-pages. Students can easily approach to the core concepts of the analysis because of the effects of our new teaching method. We offer step-by-step processes of the e-Learning content through unit-based branching scheme for difficult modules and sub-modules in our system. In addition we can offer repetitive learning processes for necessary block of given learning objects. Moreover, this method of constructing content will be considered as an advanced effectiveness of content itself.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.2 no.1
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• pp.153-169
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• 2007

It is as result that study to apply mini magnet nerve curer in peripheral nervous system disease treatment. Design and embodied action power and Control Unit in cylinder form of magnet roof object firstly. Yielded service area about special quality of probe of roof object cylinder style and treatment area dimension and distance of treatment pulse secondly. Embody pulse forming course energy value by Probe's form by third, could embody treatment pulse by disease. Specially, through a special quality experiment, saved Damping pulse form and treatment pulse form etc. variously. Lately, embodied this to aid a little in disease treatment that follow that there is no invasion that there is no stimulation by medicine development. Go amplitude treatment pulse (traditional magneto-therapy of greatly great that strong) does curative effect greatest at short time and becomes thought that demand is magnified greatly at the future in this research.

• Journal of Korean Critical Care Nursing
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• v.3 no.1
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• pp.41-51
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• 2010

Purpose: The purpose of this study was to identify the effects of family visits upon the stress response of patients and their families, Methods: This study was the interrupted time series design, The subjects consisted of 197 patients and 197 family members in the cardiac intensive care unit of S Hospital in Bucheon. Physiological stress responses such as blood pressure, heart rates, respiration rates, and oxygen saturation were measured using HP monitors. VAS was used to measure the emotional stress. Collected data was analyzed using repeated measure ANOVA, t-test by SPSS 17.0 statistical program. Results: The family visits did not change patients' blood pressure, pulse rate, respiration rate and oxygen saturation, However the anxiety level of patients and their family members were decreased significantly during family visits. Furthermore, 30-minute family visit reduced more effectively patient's anxiety than 15-minute family visit. Conclusion: Family visits need to be used as a means of nursing intervention to ease the emotional stress of patients and their families. In addition, increasing of visiting time should be considered.

• Child Health Nursing Research
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• v.18 no.4
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• pp.177-183
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• 2012

Purpose: This study was done to examine the incidence of pressure ulcers and associated factors, by inspecting the skin of newborn babies in a newborn unit or newborn intensive care unit (NICU). Methods: The participants were 101 newborn babies in either a newborn unit or NICU in D general hospital. The incidence of pressure ulcer was measured using the skin inspection tool for pressure ulcer, suggested by Agency for Health Care Policy and Research. Results: Incidence rate of pressure ulcer was 19.8%, and 80% of the newborns with pressure ulcers were premature babies. The commonest region of onset was the ear (36.8%), followed by the foot (31.6%), occipital region (15.8%) and knee (15.8%). Those are the regions related to external medical devices like nasal Continuous Positive Airway Pressure and Pulse Oximetry. Factors related to pressure ulcers were gestational period of 37 weeks or less, hospitalization for 7 days or more, birth weight under 2,500 g and a low level of serum albumin. Conclusion: The results of the study show that the skin and underlying tissues of premature infants is at risk for pressure-related skin breakdown. As most pressure ulcers are caused by medical devices, nursing interventions are required to prevent further aggravation of the lesions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.12
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• pp.3182-3196
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• 2012

In this paper, we present a new LED (Light Emitting Diode) mood lighting system interacting with smartphones based on the generation of different light sequences. In the proposed system, one light sequence is considered to be one unit of the service contents, which is then transmitted through a network and played in an LED lighting system. To this end, we propose a novel generation scheme using a smartphone, and a decoding/playing mechanism in an LED lighting system. The lighting sequences have a fixed period divided into predefined time units. Two modes - basic and interpolation - are supported in each time unit when playing a color sequence. In the basic mode, the color is maintained for the entire time unit, whereas in the interpolation mode the color is interpolated. The sequence is decoded and played in the lighting circuit by changing the duty cycle of a PWM (Pulse Width Modulation) signal. A demonstration system of the overall proposed method was using smartphones, a server and an LED lighting system. The results from this experiment show the validity and applicability of the proposed scheme.

• Korean Journal of Radiology
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• v.24 no.12
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• pp.1260-1283
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• 2023

Magnetic resonance imaging (MRI) has been extensively applied in the study of multiple sclerosis (MS), substantially contributing to diagnosis, differential diagnosis, and disease monitoring. MRI studies have significantly contributed to the understanding of MS through the characterization of typical radiological features and their clinical or prognostic implications using conventional MRI pulse sequences and further with the application of advanced imaging techniques sensitive to microstructural damage. Interpretation of results has often been validated by MRI-pathology studies. However, the application of MRI techniques in the study of neuromyelitis optica spectrum disorders (NMOSD) remains an emerging field, and MRI studies have focused on radiological correlates of NMOSD and its pathophysiology to aid in diagnosis, improve monitoring, and identify relevant prognostic factors. In this review, we discuss the main contributions of MRI to the understanding of MS and NMOSD, focusing on the most novel discoveries to clarify differences in the pathophysiology of focal inflammation initiation and perpetuation, involvement of normal-appearing tissue, potential entry routes of pathogenic elements into the CNS, and existence of primary or secondary mechanisms of neurodegeneration.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.1957-1964
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• 1994

In this thesis, a Synthetic Aperture Rarar Processor that is possible real-time handling is implemented using CW(Continuose Wave) laser as a light source, CCD(charge Coupled Device) as a time integrator, and AOD(Acousto-Optic Device) as the space integrator. One of the advantages of the proposed system is that it does not require driving circuits of the light source. To implement the system, the linear frequency modulation(chirp) technique has been used for radar signal. The received data for the unit target was processed using 7.80 board and accompanying electronic circuits. In order to reduce the smear effect of the focused chirp signal which occurs Bragg diffrection angle of the AOD has been utilized to make sharp pulses of the laser source, and the pulse made synchronized with the chirp signal. Experiment and analysis results of the data and images detected from CCD of the proposed SAR system demonstrated that detection effect is degrated as the unit target distance increases, and the resolving power is improved as the bandwidth of the chirp signal increases. Also, as the pulse width of the light source decreases, the smear effect has been reduced. The experimental results assured that the proposed system in this papre can be used as a real time SAR processor.