• 한국지능시스템학회논문지
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• 제22권6호
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• pp.754-760
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• 2012

본 논문은 MW 스케일의 배터리 에너지 저장 시스템 (BESS)을 위한 PMS (power management systems)의 장기간 스케쥴링 알고리즘의 하나로서 peak shaving 알고리즘에 대하여 설명한다. PMS의 목적은 기본적으로 배터리 모듈의 AC 입출력을 제어하는 데 있다. 1일전 부하 곡선이 제공된다는 가정 하에서, 오프라인 peak shaving 알고리즘이 적용될 수 있으나, 이 오프라인 알고리즘의 결과를 적용할 경우 부하 곡선에 존재하는 불확실성에 의하여 그 적용 결과가 실시간 운전에서는 다르게 나타날 수 있다. 본 논문에서는 PMS의 peak shaving 문제에서 부하 곡선의 불확실성을 고려하기 위하여 퍼지 LP 문제 형태로 정식화하고 그 해법과 실시간 운전 시 적용 방안에 대하여 논한다.

• Clinical and Experimental Pediatrics
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• 제62권6호
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• pp.206-212
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• 2019

Purpose: The present study aimed to determine the prevalence of childhood obesity and overweight in Iranian children under 5 years of age using a systematic review and meta-analysis. Methods: We searched MEDLINE (PubMed), Web of Science, Google Scholar, Scopus, CINHAL, and the Iranian databases, including Scientific Information Database (www.sid.ir), Iranian Research Institute for Information Science and Technology (Irandoc.ac.ir), Iranmedex (www.iranmedex.com), and Magiran (www.magiran.com), for all articles published between January 1989 and August 2017. Sources of heterogeneity were determined using subgroup analysis and meta-regression. Results: Six articles were ultimately included in the meta-analysis to estimate the pooled prevalence, based on which the prevalence of obesity and overweight were estimated to be 8% (95% confidence interval [CI], 6%-10%) and 9% (95% CI, 7%-11%), respectively. The results of the subgroup analysis showed that the prevalence of obesity in boys and girls was 9% (95% CI, 6%-13%) and 7% (95% CI, 4-10%), respectively, and the prevalence of overweight in boys and girls was 10% (95% CI, 5%-15%) and 9% (95% CI, 5%-13%), respectively. Conclusion: Despite high heterogeneity among the results of the articles included in the meta-analysis, the prevalence of obesity and overweight is higher in Iranian children under 5 years of age. Therefore, parents and the health system must pay more attention to the lifestyle, nutritional habits, and physical activity of these children.

• 한국재료학회지
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• 제29권8호
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• pp.469-476
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• 2019

A lead-free bulk ceramic having a chemical formula $Ba_{0.8}Ca_{0.2}(Ti_{0.8}Zr_{0.1}Ce_{0.1})O_3$ (further termed as BCTZCO) is synthesized using mixed oxide route. The structural, dielectric, impedance, and conductivity properties, as well as the modulus of the synthesized sample are discussed in the present work. Analysis of X-ray diffraction data obtained at room temperature reveals the existence of some impurity phases. The natural surface morphology shows close packing of grains with few voids. Attempts have been made to study the (a) effect of microstructures containing grains, grain boundaries, and electrodes on impedance and capacitive characteristics, (b) relationship between properties and crystal structure, and (c) nature of the relaxation mechanism of the prepared samples. The relationship between the structure and physical properties is established. The frequency and temperature dependence of the dielectric properties reveal that this complex system has a high dielectric constant and low tangent loss. An analysis of impedance and related parameters illuminates the contributions of grains. The activation energy is determined for only the high temperature region in the temperature dependent AC conductivity graph. Deviation from the Debye behavior is seen in the Nyquist plot at different temperatures. The relaxation mechanism and the electrical transport properties in the sample are investigated with the help of various spectroscopic (i.e., dielectric, modulus, and impedance) techniques. This lead free sample will serve as a base for device engineering.

• 전력전자학회논문지
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• 제26권3호
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• pp.192-198
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• 2021

The battery's State of Health (SOH) is a critical parameter in the process of battery use, as it represents the Remaining Useful Life (RUL) of the battery. Electrochemical Impedance Spectroscopy (EIS) is a widely used technique in observing the state of the battery. The measured impedance at certain frequencies can be used to evaluate the state of the battery, as it is intimately tied to the underlying chemical reactions. In this work, a low-cost portable EIS instrument is developed on the basis of the ARM Cortex-M4 Microcontroller Unit (MCU) for measuring the impedance spectrum of Li-ion battery packs. The MCU uses a built-in DAC module to generate the sinusoidal sweep perturbation signal. Moreover, it performs the dual-channel acquisition of voltage and current signals, calculates impedance using a Digital Lock-in Amplifier (DLA), and transmits the result to a PC. By using LabVIEW, an interface was developed with the real-time display of the EIS information. The developed instrument was suitable for measuring the impedance spectrum of the battery pack up to 1000 V. The measurement frequency range of the instrument was from 1 hz to 1 Khz. Then, to prove the performance of the developed system, the impedance of a Samsung SM3 battery pack and a Bexel pouch module were measured and compared with those obtained by the commercial instrument.

• 한국산업보건학회지
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• 제32권3호
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• pp.209-220
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• 2022

Objectives: This study was performed to suggest how to re-establish criterion for toxic substances under the Chemical Control Act (CCA) in South Korea by comparing the GHS (Globally Harmonized System of Classification and Labeling of Chemicals) score and toxic properties. Methods: Toxic substances were classified into seven groups (Acute toxicity (1A), Chronic toxicity (2C), Environmental hazards (3E), Acute toxicity & chronic toxicity (4AC), Chronic toxicity & environmental hazards (5CE), Acute toxicity & environmental hazards (6AE), and Acute toxicity & chronic toxicity & environmental hazards (7ACE)) according to their toxic properties. The GHS score was calculated to sum up five toxicity indicators (health acute toxicity, health repeated toxicity, carcinogenicity, health other chronic toxicity and environmental hazards). Results: The GHS score of 7ACE was higher by 7 times that of 1A. 1A is the only group which has lower than the total GHS score. The highest score was 47, for sodium chromate (CAS no. 7775-11-3), which belongs to group 7ACE. This is classified as acute toxicity, carcinogenicity, germ cell mutagenicity, reproductive toxicity, and acute and chronic environmental hazard. On the other hand, the lowest score was 2.75, which was assigned to 177 chemicals belonging to group 1A. When the health acute toxicity indicator was omitted from the toxic criterion, toxic substances could be divided into the sub-groups 'human chronic hazards group' (HCG) and 'environmental hazards group' (EG) according to their GHS score and properties. Conclusions: The proposed criterion for toxic substances is to establish sub-groups defined as HCG and EG for separate control and that the 1A group be moved to substances requiring preparation for accidents under the CCA.

• 한국전자통신학회논문지
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• 제17권2호
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• pp.279-290
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• 2022

초전도 한류기는 초전도 전이를 이용하여 전류를 제어하는 전력기기로, 수 msec 이내에 고장전류를 정상전류로 변환하여 전력계통의 유연성, 안정성 및 신뢰성을 높일 수 있는 기기이다. 고온초전도 선재는 상전이 속도가 빠르고 임계전류밀도가 높으며 교류손실이 적어 초전도 한류기에 적합한 소재이지만 최적화 연구가 부족함에 따라 고온초전도 선재 특성에 의존하는 기존 방식은 한류소자의 설계, 투입 선재의 양 등에 있어 비효율적이다. 따라서 초전도 한류기에 적합한 선재를 개발하기 위해 임계전류 균일도 향상, 최적의 안정화재 재료 선정 및 균일 적층 기술 개발 연구가 수행되었다. 본 연구를 통하여 개발된 고온 초전도 선재는 710m 길이에서 평균 804 A/12mm-w의 임계전류를 가지는 선재제조 기술을 확보함에 따라 효율성 향상, 비용 절감 및 크기 축소로 경제적 성과를 확보할 수 있었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.178-180
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• 2020

기존의 철도차량용 무선전력전송 시스템은 Medium-voltage (MV) 60 Hz 중전압 AC 계통 전압을 Low-voltage (LV) DC로 변환하기 위해 저주파 변압기와 정류기를 사용한다. 하지만 수 MW급의 대전력을 낮은 DC 전압으로 전송하려면 인버터는 수백 A - 수 천 A 이상의 전류용량을 가져야하므로 정류기의 출력 단에 직렬 또는 병렬로 연결된 여러 개의 고주파 변압기를 필요하게 된다 (그림 1참조). 이러한 저주파 변압기, 정류기 및 고주파 변압기는 크고 무거우므로 낮은 전력밀도 및 높은 시스템 가격의 원인이 된다. 본 논문에서는 이러한 저주파변압기, 정류기, 고주파 변압기를 사용하지 않는, 여자 코일을 이용한 새로운 멀티레벨 무선전력전송 시스템의 토폴로지를 제안한다. 제안된 멀티레벨 무선전력전송 시스템은 멀티레벨 인버터의 각 출력 단에 여자코일 (excitation coil) 이 연결되어 있다. 이 여자코일들은 급전코일 (transmitter coil) 에 전기적으로는 절연되었지만 자기적으로 강하게 결합된다. 여자코일들이 발생시킨 자기장은 급전코일에 유도전압을 발생시키고, 급전코일에서 수백 A 이상의 큰 전류를 흐르게 하여 급전코일에서 강한 자기장을 발생하도록 한다. 이 자기장은 급전코일과 수 cm 이상 떨어져 자기적으로 약하게 결합된 집전코일 (receiver coil) 에 다시 유도전압을 발생시켜 전력을 전달하게 된다. 제안한 새로운 멀티레벨 무선 전력 전송 시스템은 시뮬레이션을 통해 검증했다.

• 한국입자에어로졸학회지
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• 제19권3호
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• pp.63-76
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• 2023

An electrostatic precipitator (ESP) has a low pressure drop and a high collection efficiency but its collection efficiency can be reduced due to dust accumulation on the collection plates during long-term operations. In order to maintain the initial dust collection efficiency, it is necessary to periodically clean the collection plates. The common cleaning methods are using physical impacts or water sprays. These cleaning methods can lead to damage to the collection plate or generate wastewater. Herein, we implemented an electrodynamic screen (EDS) for ESP cleaning and evaluated its surface cleaning performance of particles. The EDS is an electrostatic system that can electrostatically repel particles on surfaces, allowing it to clean the ESP without causing damage and wastewater generation. Our evaluation included the analysis of the effects of AC voltage characteristics, electrode configuration and environmental conditions on the cleaning performance of the EDS with the aim of achieving effective surface cleaning. It has been demonstrated that activating the EDS cleans up to 65% of the particles on the surface, which indicates about 94% of our target cleaning zone.

• 수산해양기술연구
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• 제36권3호
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• pp.257-265
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• 2000

본 논문에서는 BLDC 서보모터의 속도 제어성 향상을 위해 속도제어계에 2자유도 적분형 최적 제어법을 적용하고 그 결과를 기존의 PI제어계 및 2자유도 PI제어계와 비교하였다. 2자유도 적분형 최적제어법은 PI제어법이 갖는 지령치 추종특성과 외란 억제특성간의 트레이드오프 문제를 해결하고, 제어계의 최적성을 확보하고자 도입되어졌으며, 시뮬레이션과 실험을 통해 그 유효성을 고찰하였다. 시뮬레이션을 통해 얻은 결과는 다음과 같다. (1) 2자유도 적분형 최적제어계는 PI제어계에 비해 양호한 지령치 추종성과 외란 및 모델링 오차제거 특성을 보였다. (2) 2자유도 적분형 최적제어계는 제어파라미터인 하중행렬 Q, R 및 W에 대한 제약요건이 없을 경우, 모터의 정격조건 하에서 이들을 적절히 설정함으로써 2자유도 PI제어계보다도 양호한 지령치 추종성과 외란 및 모델링 오차 제거 특성을 얻을 수 있다. (3) 2자유도 적분형 최적제어계는 인가전압 및 전류의 크기를 2자유도 PI제어계의 그것과 동일하게 제약할 경우 2자유도 PI제어계에 비해 지령치 추종에 관한 정정시간 외에는 그다지 우수한 성능을 보이지 않았다. 또한, 실험을 통해 고찰한 PI 및 2자유도 PI제어계의 속도추종성능은 시뮬레이션 결과와 거의 동일하였다. 2자유도 적분형 최적제어계에 대한 실험결과는 논문에 나타내지 못하였으나, PI및 2자유도 PI제어계의 실험결과에서 알 수 있듯이 2자유도 적분형 최적제어계도 시뮬레이션 결과와 같은 경향을 보일 것으로 사료된다. 따라서, 본 논문에서 검토된 방법은 기존의 PI 제어계가 갖는 지령치 추종과 외란억제의 트레이드오프 문제를 상당부분 해결 가능할 것으로 보인다. 또한, 일정의 부하외란 및 모델링 오차내에서는 2자유도 PI제어계 보다 나은 제어성능을 보여 BLDC 모터의 속도 제어성 향상에 기여할 수 있을 것으로 기대가 된다. 향후, 2자유도 적분형 최적제어계의 실험결과를 통한 엄밀한 제어성능검증과 스텝외란 외의 주기성 외란 인가시 2자유도 적분형 최적제어계의 외란제거 방안 등이 검토되어야 할 것으로 사료된다.

• 대한간호학회지
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• 제24권4호
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• pp.696-705
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• 1994

This study was done to provide a basis for home health care management for women following Cesarean delivery. Furthermore it was initiated as an possible application of home health care in the future. In this study, client selection criteria was developed by the researcher and assessment tools for home health care, recording system and problem oriented recording system were revised from Jun's(1993) methods. The selection criteria tool for home health care for women who had a Cesarean delivery was structured and consisted of five areas : physical status, functional status, psychological-emetional status, educational needs status and environmental status. The structured assessment tool consisted of general items, obstetric history, past medical history, methods of feeding, medications taken before ad-mission, laboratory results, discharge instructions, discharge medications, family tree, economic status, environmental status, a map, health assessment of women and their newborns. The visit note consisted of the date : nursing problems : nursing process including initial assessment : nursing goals : visit plan : health status of the postpartum women and their newborn : nursing diagnoses : nursing implementation evaluation : summary : next visit plan and revision. The problem oriented recording system consisted of the date, problem numbers, nursing diagnoses, problem appearance date, problem resolution date. The results of the research are as follows : The seven cases having had a Cesarean delivery were discharged on an average on the 5th day after the Cesarean birth. The total number of home visits was 13. According to Cordon's functional health patterns the total possible nursing diagnoses was 34 diagnoses for the methers and their newborns. Among the 34 diagnoses, there were 13 diagnoses in the health perception /management pattern, 7 in the psychosocial health perception / management pattern, 8 in the psychosocial self-perception, 2 in the nutrition / metabolism pattern of physical function, 2 in the knowledge deficit of newborn management, anxiety related to newborn management, knowledge deficit related to disease process of new-born, anxiety related to disease process of newborn anxiety related to prognosis of baby's condition, knowledge deficit related to newborn jaundice each appeared once. The changes in the number of nursing diagnoses was related to not the number of visits but to the number of nursing diagnoses decreasing. The con-tent of the home health care was categorized ac-cording to assessment, direct care, counseling, education, family care. The recommendation based on the results of this research are Home health care nurses for Cesarean postpartum women and their neonates requires comprehensive knowledge of pregnancy, delivery, and the postpartum period and of the neonate so that they can provide appropriate care and holistic views. Most of cases terminated after the second visit, this outcome may be related to the subjects being discharged on the 5th day after delivery. Therefore, study done with earlier discharge after delivery may have different outcome. It is very hard to assess psychological aspects that need follow-up and to develop communication channels.