• 전력전자학회논문지
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• 제19권1호
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• pp.31-40
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• 2014

This paper describes an optimal configuration for multi-central inverters in a medium-voltage (MV) grid, which is suitable for large-scale photovoltaic (PV) power plants. We theoretically analyze a proposed common-mode equivalent model for problems associated with multi-central transformerless-type three-phase full bridge(3-FB) PV inverters employing two-winding MV transformers. We propose a synchronized PWM control strategy to effectively reduce the common-mode voltages that may simultaneously occur. In addition, we propose that the existing 3-FB topology may also have the configuration of a multi-central inverter with a two-winding MV transformer by making a simple circuit modification. Simulation and experimental results of three 350kW PV inverters in a multi-central configuration verify the effectiveness of the proposed synchronization control strategy. The modified transformerless-type 3-FB topology for a multi-central PV inverter configuration is verified using an experimental prototype of a 100kW PV inverter.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.427-432
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• 2012

This paper proposes efficient operation method of PV system consisted of multi-central which is suitable for large scale system. The multi-central system used switch at a DC-link and applied proposed algorithm can improve the efficiency and the reliability on the existing system. This algorithm, with advantage of Multi-Central system can minimize the effect of different characteristic of each PV array due to a shadow or damaged PV cell. Each system is analysed and maximum power point tracking control, DC-link voltage control and output current control is used commonly. The validity is verified after comparing of the existing system and proposed system by simulation.

• International Journal of Industrial Entomology and Biomaterials
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• 제14권2호
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• pp.81-85
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• 2007

White Muscardine is the most common fungal disease of silkworm, Bombyx mori L. caused by the pathogenic fungus, Beauveria bassiana (Balsamo) Vuillemin. In the present investigation, an attempt has been made to screen locally available medicinal/ weed plants against Beauveria bassiana. Among the plant extracts (PE) tested, 5% aqueous crude extract of the bulb of Allium sativum (Garlic) has been found to be most effective against Beauveria bassiana. The radial growth of Beauveria bassiana in vitro was inhibited to the tune of 54.9% in aqueous extract and 54.4% in ethanolic extract of Allium sativum and correspondingly mycelial dry weight gave rise to 110.7 mg and 108.7 mg against 201.7 mg in control 15 days post treatment. Similarly, silkworm larvae topically inoculated with the Beauveria bassiana conidia ($1.8{\times}10^6/ml$) registered survival up to 53.0% against 0.0% in control after treatment with aqueous extract of Allium sativum. Simultaneously, as a preventive measure, silkworm larvae were put to rear in conidia contaminated seat paper instantly treated with aqueous extract of Allium sativum that also increased survival up to 61.0% against 4.6% in control. It is also observed that the plant extract is absolutely innocuous to silkworm.

• 한국환경보건학회지
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• 제46권5호
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• pp.599-609
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• 2020

Objectives: Coronavirus disease 2019 (COVID-19) first emerged in December 2019 in Wuhan, China, and has rapidly become a global pandemic with over 26.4 million confirmed cases and approximately 871,000 fatalities worldwide as of this writing. In the Republic of Korea, disease clusters frequently occurred in long-term care hospitals where the majority of residents are elderly with underlying medical conditions. Despite the fact that public health authorities and local community health centers have put tremendous efforts into preventing the spread of disease, positive cases have continued to occur. Thus, the Korea Centers for Disease Control & Prevention rapid response team decided to conduct an environmental investigation of a long-term care hospital to identify whether environmental contamination has remained and contributed to the spread of COVID-19. Methods: An environmental investigation was conducted at Hospital A. The characteristics of the facility and its HVAC system were assessed by checking the layout and interviewing the people in charge. A total of 64 surface samples were collected from areas of concern, including patient rooms, toilets, elevators, and nurses' station. These samples were tested by a regional health and environmental research institute using real-time reverse transcription polymerase chain reaction. Results: All samples from Hospital A were confirmed to be negative. Through interviews with high-level personnel at the regional community health center, we found that extensive disinfection is frequently performed on potentially contaminated areas in Hospital A in accordance with government guidelines. Conclusion: The environmental control measures implemented in Hospital A had been sufficient for mitigating the risk of further infection, suggesting that such measures may also be effective for other long-term health care facilities.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.314-316
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• 2005

Light flicker is a notorious phenomenon influencing light quality. The flicker of the light flux outputs from the light sources perceived by human eyes depends upon the lamp brightness fluctuations for projector display. This paper describes a ballast ignition control system, which makes the lamp strike frequency phase lock the blanking time period to minimize the flicker effect

• 한국산학기술학회논문지
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• 제17권6호
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• pp.113-120
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• 2016

본 연구의 목적은 유치도뇨관, 중심정맥관 및 인공호흡기 감염관리지침에 대한 중환자실 간호사의 지식과 수행도 정도를 파악하고자 하였다. 대상자는 2개의 상급종합병원과 3개의 종합병원의 중환자실에서 근무하는 간호사 175명이다. 자료수집은 2013년 7월 1일부터 7월 31일까지로, 수집된 자료는 SPSS 18.0 통계 프로그램을 사용하여 기술통계, t-test, ANOVA로 분석하였다. 각 지식수준은 유치도뇨 관리관(평균 0.87점), 중심정맥관(0.82점), 인공호흡기(0.82점)순으로 나타났으며, 수행도는 유치도뇨 관리관(평균 4.18점), 인공호흡기(4.04점)중심정맥관(4.07점)순이었다. 지식과 수행도에서는 유치도뇨관(r=.72, p<.00), 중심정맥관(r=.54, p<.001), 및 인공호흡기(r=.30, p<.001) 감염관리간 순 상관관계를 나타냈다. 유치도뇨관 감염관리지침에 대한 지식과 수행도는 성별, 최종학력, 근무경력, 담당환자 수, 병원규모, 세미나 참석 여부에 따라 통계적으로 유의한 차이가 있었다. 중심정맥관 감염관리지침에 대한 지식과 수행도는 최종학력, 근무경력, 담당환자 수, 병원규모, 세미나 참석 여부에 따라 통계적으로 유의한 차이가 있었다. 인공호흡기 감염관리지침에 대한 지식은 근무경력에 따라 통계적으로 유의한 차이가 있었다. 본 연구결과를 기초로 감염관리지침에 대한 지식과 수행을 향상 시킬 수 있는 교육 및 훈련 프로그램이 개발되어야 할 것이다.

• 한국산업융합학회 논문집
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• 제7권2호
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• pp.207-213
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• 2004

This paper describes the development of Behind-Tape-Reader (BTR) type DNC system using CYBER 180-830 as a central computer and IBM PC-AT cell control computer and NC lathe with FANUC 5T NC controller. In this system, the connection between central computer and cell control computer is done via RS-232C serial interface board, and that between cell control computer and FANUC 5T controller is done via parallel interface board. The software consists of two module, central computer communication module for NC program downloading and status uploading, NC machine running module for NC operating.

• 대한기계학회논문집
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• 제18권4호
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• pp.805-815
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• 1994

The development of automatic production systems has a trend toward Computer Integrated Manufacturing System(CIMS) in recent years. In hardware configuration, CIMS are composed of intelligent CAD/CAM work stations, multifunction CNC machining centers including material handling systems. The DNC systems present the key element of automation hierarchy in a FMS. A DNC system is one which connects a number of numerically-controlled machines to a common memory in a digital computer for part program storage with provision for on-demand distribution of part program data to machines using communication in hierarchical structure of central computer, control computer and cell controller. This paper describes the development of Behind-the-Tape-Reader(BTR) type DNC system using CYBER 180-830 as a central computer and IBM PC-386 cell control computer and NC lathe with FANUC 5T NC controller. In this system, the connection between central computer and cell control computer is done via RS-232C serial interface board, and the connection between cell control computer and FANUC 5T controller is done via parallel interface board. The software consists of two module, central computer communication module for NC program downloading and status uploading, NC machine running module for NC operating.

• Journal of Acupuncture Research
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• 제15권2호
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• pp.301-310
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• 1998

Infrared thermographic imaging visualizes noninvasively various abnormal condition by detecting the skin temperature. As the imaging represents the objective condition by the changes in blood flow under the control of autonomic nervous system, it is used to diagnosis and monitor the lumboscral radiculopathy. And asymmetry is important in the diagnosis of disc herniation. The most common type of disc herniation occurs psoterolaterally. This frequently causes nerve root compression leading to a radiculopathy in the distribution of the involved nerve root, most of which also provoke the asymmetric changes in thermography. Central disc herniation, which accounts for 5% to 35% of disc herniation, is typically associated with low back pain. But radiculopathy is usually abscent unless central disc heriniaton is large enough to cause compression of the cauda equina. To evalute the diagnostic value of the thermographic imaging in the diagnosis of central disc herniation, the imaging of 15 normal subjects and 48 patients with central disc herniation documented by CT scan were analyzed. The patients had either bilateral radiculophathy or no radiculopathy. The imaging of patient group with non rediculopathy did not show any significant thermal difference to control. While bilateral radiculopathy group reveled hypothermic pattern compared twith control. Thermal difference between left and right side did not present any significance in non radiculopathy group but hypothermia in bilateral radiculopathy group. Large herniation group demonstrated hyperthemic pattern while the others showed no significant change. Cranial caudal thermal difference did not show any difference between experiment groups. These results shows that infrared thermographic imaging can be used central disc herniation with bilateral radiculopathy, while it seems to little useful on the diagnosis of non radiculopathic disc herniation.

• Journal of Power Electronics
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• 제9권2호
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• pp.320-333
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• 2009

A Photovoltaic (PV) system's power output varies with the change of climate. Frequency deviations, tie line voltage swings are caused by the varying PV power when large PV power from several PV systems is fed in the utility. In this paper, to overcome these problems, a simple coordinated control method for smoothing the variations of combined PV power from multiple PV systems is proposed. Here, output power command is formed in two steps: central and local. Fuzzy control is used to produce the central smoothing output power command considering insolation, variance of insolation and absolute average of frequency deviation. In local step, a simple coordination is kept between the central power command and the local power commands by producing a common tuning factor. Power converters are used to achieve the same output power as local command power employing PI control law for each of the PV generation systems. The proposed method is compared with the method where conventional Maximum Power Point Tracking (MPPT) control is used for each of the PV systems. Simulation results show that the proposed method is effective for smoothing the output power variations and feasible to reduce the frequency deviations of the power utility.