• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.142-144
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• 2008

This paper is studied on the characteristic analyses of a high performance buck-boost converter added electric isolation by using a soft switching method. To be achieved of a high performance system, the proposed buck-boost converter is constructed by using a partial resonant circuit. The control switches using in the converter are operated with soft switching for a Partial resonant method. The controlling switches are operated without increasing their voltage and current stresses by the soft switching technology. The result is that the switching loss is very low and the converter efficiency is high. And the proposed converter is added in a electric isolation. When the power conversion system is required to electric isolation, the proposed converter is adopted with the system development of high efficiency. The soft switching operation and system efficiency of the proposed converter is verified by digital simulation and experimental results.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.15-16
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• 2010

This paper is study on a high efficiency DC-DC converter of discontinuous conduction mode (DCM) added electric isolation. The converters of high efficiency are generally made that the power losses of the used semiconductor switching devices is minimized. To achieve high efficiency system, the proposed converter is constructed by using a quasi resonant circuit. The control switches using in the converter are operated with soft switching by quasi resonant method. The control switches are operated without increasing their voltage and current stresses by the soft switching technology. The result is that the switching loss is very low and the efficiency of the system is high. The proposed converter is also added electric isolation which is used a pulse transformer. When the power conversion system is required electric isolation, the proposed converter is adopted with the converter system development of high efficiency. The soft switching operation and the system efficiency of the proposed converter are verified by digital simulation and experimental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.3
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• pp.81-89
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• 2002

The sensorless AC motor drive is a popular topic of study due to the cost and reliability of speed and position sensors. Most sensorless algorithms are based on the mathematical modeling of motors including electrical variables such as phase current and voltage. Therefore, the accuracy of such variables largely affects the performance of the sensorless AC motor drive. However, the output voltage of the SVPWM-VSI, which is widely used in sensorless AC motor drives, has considerable errors. In particular, the SVPWM-VSI is error-prone in the low speed range because the constant DC link voltage causes poor resolution in a low output voltage command and the output voltage is distorted due to dead time and voltage drop. This paper investigates a novel high-performance strategy for overcoming these problems in a sensorless ac motor drive. In this paper, a variation of the DC link voltage and a direct compensation for dead time and voltage drop are proposed. The variable DC link voltage leads to an improved resolution of the inverter output voltage, especially in the motor's low speed range. The direct compensation for dead time and voltage drop directly calculates the duration of the switching voltage vector without the modification of the reference voltage and needs no additional circuits. In addition, the proposed strategy reduces a current ripple, which deteriorates the accuracy of a monitored current and causes torque ripple and additional loss. Simulation and experimentation have been performed to verify the proposed strategy.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.215-217
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• 2002

In this paper, a new converter for utility interactive photovoltaic system is proposed, the conventional utility interactive photovoltaic system is composed of a PWM inverter and a DC converter. However, the increased switching loss and the high frequency switching noise become a problem. the control accuracy of the system is made to lower by the dead time of the switching devices. and it becomes a cause of the lower conversion efficiency. In order to resolve those problems, we applied a non- dissipative snubber circuit to a converter, which generates the single phase absolute value of sinusoidal current. the converter consists of two switching devices and one capacitor which constitute a non-dissipative snubber circuit. the proposed circuit is very useful to minimize and increase efficiency, when it is used to an utility interactive photovoltaic system. it is confirmed by simulation that the proposed converter for new photovoltaic system has stable operation and good output.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.131-135
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• 2005

Gallium nitride (GaN) powders and nanowires were prepared by using tris(N,N-dimethyldithiocarbamato)gallium(III) (Ga(DmDTC)$_3$) and tris(N,N-diethyldithiocarbamato)gallium(III) (Ga(DeDTC)$_3$) as new precursors. The GaN powders were obtained by reaction of the complexes with ammonia in the temperature ranging from 500 to 1100 ${^{\circ}C}$. The process of conversion of the complexes to GaN was monitored by their weight loss, XRD, and $^{71}$Ga magic-angle spinning (MAS) NMR spectroscopy. Most likely the complexes decompose to $\gamma$ -Ga$_2$S$_3$ and then turn into GaN via amorphous gallium thionitrides (GaS$_x$N$_y$). The reactivity of Ga(DmDTC)$_3$ with ammonia was a little higher than that of Ga(DeDTC)$_3$. Room-temperature photoluminescence spectra of asprepared GaN powders exhibited the band-edge emission of GaN at 363 nm. GaN nanowires were obtained by nitridation of as-ground $\gamma$ -Ga$_2$S$_3$ powders to GaN powders, followed by sublimation without using templates or catalysts.

• Journal of Chest Surgery
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• v.48 no.3
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• pp.220-224
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• 2015

A patient presented with loss of consciousness and conversion. During an exercise test, catecholaminergic polymorphic ventricular tachycardia (CPVT) resulted in cardiac arrest. He started taking medication (a beta-blocker and flecainide) and an implantable cardioverter defibrillator (ICD) was inserted, but the ventricular tachycardia did not resolve. Left cardiac sympathetic denervation (LCSD) was then performed under general anesthesia, and the patient was discharged on the second postoperative day without complications. One month after the operation, no shock had been administered by the ICD, and an exercise stress test did not induce ventricular tachycardia. Although beta- blockers are the gold standard of therapy in patients with CPVT, thoracoscopic LCSD is safe and can be an effective alternative treatment option for patients with intractable CPVT.

• Journal of Oriental Neuropsychiatry
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• v.14 no.2
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• pp.191-198
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• 2003

Dissociative amnesia is a psychiatric disorder charicterized by a sudden loss of memory, but which has no organic disease or explanation, It usually occurs after severe psychosocial stress or traumatic experience. As for medical treatment, medicine, psychotherapy and hypnosis are used. This case describes a 35-years-old woman who developed amnesia and depression following severe troublesome events. So she suited without expression and appealed against headache, dizziness, chest discomfort and weakness. Psychoanalytic psychotherapy was enforced for three days with hypnosis. She expressed the felling over the incident which she dose not like, and canceled in the past. She became reconciled with the family and left the husband by the heart. Then she recovered memory completely and body condition also improved. Recovery and growth of self were helped using supportive expression in order to prevent a recurrence. The prognosis is good with complete recovery, and there was no relapse.

• Mass Spectrometry Letters
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• v.1 no.1
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• pp.29-32
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• 2010

Cross reacting antibodies can cause an overestimation of the results of immunoassays. Therefore, alternative methods are needed for the accurate quantification of steroids. Gas chromatography combined with isotope-dilution mass spectrometry (GC-IDMS) is developed to quantify urinary active androgens, testosterone, epitestosterone and dihydrotestosterone, which are clinically relevant androgens to both hair-loss and prostate diseases. The method devised involves enzymatic hydrolysis with $\beta$-glucuronidase, solid-phase extraction, liquid-liquid extraction using methyl tert-butyl ether and subsequent conversion to pentafluorophenyldimethylsilyl-trimethylsilyl (flophemesyl-TMS) derivatives for sensitive and selective analysis in selected-ion monitoring mode. Flophemesyl-TMS derivatization not only eliminates matrix interference but also has a good peak resolution within a 6 min-run. A selective and sensitive GC technique with flophemesyl-TMS derivatives also allows accurate quantitative analysis of three active androgens when combined with IDMS. The limit of quantification of the three analytes was <50 pg/mL, and extraction recoveries ranged from 91.9 to 102.1%. The precision and accuracy were 1.2~6.5% and 89.0~106.7%, respectively. This GC-IDMS method can be useful for evaluating the drug efficacy and monitoring the biological processes responsible for male-pattern baldness and prostate diseases.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.21 no.1
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• pp.17-21
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• 2010

Dysphonia is a medical terminology for voice disorders characterized by hoarseness, harshness, weakness, or even loss of voice ; any impairment in ability to produce voice sounds using the vocal organs, larynx, The causes of dysphonia can be classified into two groups, organic and functional. Functional dysphonia includes spasmodic dysphonia, muscle tension dysphonia, mutational dysphonia and conversion dysphonia, etc, The findings of laryngoscopy in these dysphonia are almost normal. Therefore, physicians should diagnosis these diseases from careful history taking and abundant understandings about the phonation pattern, Organic dysphonia is caused by anatomical problems in the larynx, especially on the vocal fold, Some lesions, however, are not easily found because these lesions are too small, or located on the lower lip of vibrating vocal fold. Laryngopharyngeal reflux induced laryngitis, vascular lesions, sulcus vocalis, vocal atropy including presbylaryngis, and mucosal tears are common lesions easily missed in laryngoscopy, Therefore, a high index of suspicion is necessary to avoid missing vocal fold mucosal lesions, and the strobovideolaryngoscopy is indispensable in making the diagnosis,

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.8
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• pp.416-422
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• 2006

With the increasing demand for renewable energy, distributed power included in fuel cells have been studied and developed as a future energy source. For this system, a power conversion circuit is necessary to interface the generated power to the utility. In many cases, a high step-up dc/dc converter is needed to boost low input voltage to high voltage output. Conventional methods using cascade dc/dc converters cause extra complexity and higher cost. The conventional topologies to get high output voltage use flyback dc/dc converters. They have the leakage components that cause stress and loss of energy that results in low efficiency. This paper presents a high boost converter with a voltage multiplier and a coupled inductor. The secondary voltage of the coupled inductor is rectified using a voltage multiplier and series-connected with the boost voltage of primary voltage of the coupled inductor. Therefore, high boost voltage is obtained with low duty cycle. Theoretical analysis and experimental results verify the proposed solutions using a 300W prototype.