• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권6호
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• pp.274-278
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• 2005

Voltage transformer(VT) comparison measurement system is usually used for measurements of ratio error and phase angle error of VT made in industry. Both ratio error and phase angle error in VT are critically influenced by values of burden of VT used. External burden effects on both ratio error and phase angle error in VT are theoretically calculated. From the theoretical calculation, a method of evaluation for linearity of ratio error and phase angle error in VT measurement system have been developed using the standard capacitive burdens, with negligible dissipation factor less than 10$^{-4}$. These burden consists of five standard capacitors, with nominal capacitance of 1.1 $\mu$F, 1 $\mu$F, 0.1 $\mu$F, 0.01 $\mu$F, 0.001 $\mu$F. The developed method has been applied in VT measurement system of industry, showing in good consistency and linearity within 0.001 $\%$ between theoretical and measured values.

• 한국발생생물학회지:발생과생식
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• 제22권1호
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• pp.1-8
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• 2018

The annual reproductive cycle of the Korean endemic slender catfish, Silurus microdorsalis, was examined histologically regarding water temperature and day length of habitat, gonadosomatic index (GSI), and development characteristics of female and male gonads. The maximum GSI value was found in May, $1.23{\pm}0.33$ and $11.77{\pm}3.23$ for male and female respectively (habitat water temperature $21.5^{\circ}C/13.59hr$ day length). On the other hand, the minimal level was $0.63{\pm}0.10$ in July ($26.5^{\circ}C/14.17$) for male and $1.36{\pm}0.08$ in October ($20^{\circ}C/11.2hr$) for female. We compared and calculated the stages of testis and ovary development process in order to determine the germ cell development characteristics and the reproductive cycle. According to results, we classified the annual reproductive cycle of the slender catfish into five stages: Growing phase (December-February), Mature phase (March-April), Ripe and spawning phase / Releasing phase in male (May-June), Degenerative phase (July-August), and Resting phase (September-November).

• 설비공학논문집
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• 제25권9호
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• pp.477-483
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• 2013

A numerical analysis of solid-liquid phase change was performed on a heat transfer module which consisted of circulating water path (BRINE), heat transfer plate (HTP) and phase change material (PCM) layers, such as high temperature PCM (HPCM, $78{\sim}79^{\circ}C$) and low temperature PCM (LPCM, $28{\sim}29^{\circ}C$). There were five arrangements, consisting of BRINE, HTP, LPCM and HPCM layers in the heat transfer module. The time and heat transfer rate for melting/solidification was compared to their arrangements, against each other. As results, the numerical time without convection was longer than the experimental one for melting/solidification. Moreover, the melting/solidification with the BRINE I-LPCM-BRINE II-HPCM arrangement was faster(10 hours) than the others; HPCM-BRINE-LPCM, BRINE I-HPCM-LPCM-BRINE II one.

• 한국대기환경학회지
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• 제34권4호
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• pp.616-624
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• 2018

In this study, a previous DNPH (2,4-dinitrophenylhydrazine) coupled with high performance liquid chromatography (HPLC) method to measure the concentration of formaldehyde in ambient and source environments has been improved. To improve the disadvantage of the previous HPLC method, an appropriate composition ratio of mobile phase (water: acetonitrile (ACN)) was determined and an isocratic analysis was conducted. Furthermore, limit of detection (LOD), limit of quantitation(LOQ), accuracy, and precision were investigated to verify the reliability of the analytical conditions determined. Finally, samples of exhaust gases from five different industrial facilities were applied to HPLC analytial method proposed to determine their formaldehyde concentrations. The appropriate composition ratio of the mobile phase under the isocratic condition was a mixture of water(40%) and ACN(60%). As the volume fraction of the organic solvent ACN increases, retention time of the formaldehyde peak was reduced. Detection time of formaldehyde peak determined using the proposed isocratic method was reduced from 7 minutes(previous HPLC method) to approximately 3 minutes. LOD, LOQ, accuracy, and precision of the formaldehyde determined using standard solutions were 0.787 ppm, 2.507 ppm, 93.1%, and 0.33%, respectively, all of which are within their recommended ranges. Average concentrations of the formaldehyde in five exhaust gases ranged from 0.054 ppm to 1.159 ppm. The lowest concentration (0.054 ppm) was found at samples from waste gas incinerator in a bisphenol-A manufacturing plant. The highest was observed at samples from the absorption process in manufacturing facilities of chemicals including formaldehyde and hexamine. The analytical time of the formaldehyde in ambient air can be shortened by using the isocratic analytical method under appropriate mobile phase conditions.

• 대한간호학회지
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• 제50권4호
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• pp.583-598
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• 2020

Purpose: This study was to investigate the operational status of the midwifery birthing centers (MBCs) and midwives' job status (Phase 1) and to develop midwifery practice guidelines (MPG) (Phase 2) in Korea. Methods: In the first phase, the subjects were 15 midwives who operated 11 of 14 MBCs that were opened as of August 2018. The questionnaire consisted of items to measure the operational status of the MBC and midwives' job status. In the second phase, the MPG was developed from literature review, interviews with five midwives opening their MBCs, surveys with 74 midwives, and a validity evaluation conducted by seven experts. Results: The distribution of operating MBCs was five in Gyunggi-do, two each in Seoul and Incheon, one each in Busan, Chungcheongbuk-do, Gyeongsangbuk-do, Gyeongsangnam-do and Jeju-do. The mean age of midwives was 54.3 and all were female. In 2017, a total of 762 births including 81 homebirths were performed by midwives. The job performance was highest in the order of neonatal care 3.81, childbirth care 3.56, and postpartal care 3.53, respectively. The MPG included seven areas of prenatal care, childbirth care, postpartal care, neonatal care, primary health care, law/ethics, and administration, with 56 tasks and 166 task elements. Conclusion: This study provides the valid basic data for the operational status of the MBC and the midwives' job status. The MPG describes the midwife's job and may be used as basic data for preparing policies for the development of midwifery practice in Korea.

• 정보처리학회논문지B
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• 제18B권4호
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• pp.213-220
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• 2011

본 논문은 조기 화재 경보 시스템에서 예측하지 못한 위험요소들의 이벤트에 즉각 응답하는 비디오 기반의 효과적인 4단계 연기 감지 방법을 제안한다. 첫 번째 단계에서는 근사 미디언(approximate median) 방법을 사용하여 비디오의 현재 프레임에서 움직이는 영역들을 분리한다. 두 번째 단계에서는 연기의 칼라 기반 분리 기법을 사용하여 이러한 움직이는 영역들로부터 후보 연기 영역을 선택한다. 세 번째 단계에서는 특징추출 알고리즘을 사용하여 연기의 움직임이나 지역 불규칙성과 같은 후보 연기 영역들의 특징을 분석하여 연기의 다섯 가지 특징 파라미터를 추출한다. 네 번째 단계에서는 추출된 다섯 가지 특징 파라미터를 K-nearest neighbor (KNN) 알고리즘의 입력으로 사용하여 후보 연기 영역이 연기인지 아닌지를 구분한다. 모의실험 결과, 제안하는 4 단계 연기 감지 방법은 기존의 연기 감지 알고리즘들과 비교하여 연기감지의 정확도에서 우수한 성능을 보였고, 또한 오픈된 넓은 공간에서도 높은 신뢰성과 낮은 오류 경보율을 보였다.

• 융합정보논문지
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• 제7권5호
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• pp.83-88
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• 2017

본 논문은 F-16 전투기 축소모델을 사용한 위상비교 방향 탐지 장치의 방위각 정확도 시험에 대해서 기술하였다. 전투기 하부면에 안테나를 배치하면 항공기 구조물에 의한 전파 반사가 일어나서 방위각 측정오차가 발생한다. 본 연구에서는 F-16 전투기를 5:1로 축소 모델링하고 전투기 하부면에 5개 안테나를 원형으로 설치한 다음 $0-360^{\circ}$ 방위각에서 $1^{\circ}$ 간격으로 전파를 수신하였다. 이 때 5개 안테나에 수신되는 전파의 위상을 수치해석으로 계산하여 방향 탐지정확도 시험을 실시하였다. 축소모델을 사용해서 시험한 위상비교 방향 탐지 방식의 방위각 오차는 신호잡음세기가 0dB 이상인 경우 평균 $0.5^{\circ}$ 이하로 측정되어서 전투기의 위상비교 방향 탐지 장치 설계에 유용하게 활용할 수 있을 것으로 판단된다.

• 동의생리병리학회지
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• 제22권6호
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• pp.1374-1377
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• 2008

The aim of this study is to explore the principle that the joints of the limbs belong to Five Phases in Korean medicine. According to the principle of I-Ching, Ha-Do provides the logic which could attach everything to Five Phases. Ha-Do is composed of the numbers from one through ten, and in order to explain the logic of Universe formation, it furnishes the method of transforming 'immateriality' into 'materiality'. If we apply formation theory of Ha-Do to the joints of the limbs, however, it could be understood that the trunk of body develops the appendages, which means Ha-Do suggests a logic that 'materiality' generates 'materiality' in this case. Therefore, it is not the Water but the Earth that occurs first in the appendages development in this theory, and the shoulder joints belong to the Earth. Following development should occur in order of Five Phases formation of Ha-Do ; that is to say, the elbow joints belong to the Water, the wrist joints belong to the Fire, the finger joints belong to the Wood, and the ends of fingers belong to the Metal.

• Journal of Power Electronics
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• 제17권1호
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• pp.161-171
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• 2017

To enhance the reliability of two-motor drive systems, this paper proposes an improved direct torque control (DTC) scheme (P-DTC) for five-leg dual-PMSM drive systems. First, the topology of a five-leg dual-PMSM drive system is illustrated. To clarify the analysis of the P-DTC, the standard DTC scheme for three-phase drive systems is presented. The operation of a five-leg dual-PMSM drive system is classified into three situations according to the definitions of the switching-vector unions. Compared with the existing DTC scheme (R-DTC), the P-DTC can minimize the replacement of active switching-vectors to zero switching-vectors. When this replacement cannot be avoided, the P-DTC uses a proposed master-slave selection principle to minimize the system error. Comparing with the R-DTC, the P-DTC has lower torque ripples, a wider speed range and a faster torque increasing response. Experiments have been carried out in the coupling and independent modes, and the effectiveness of the P-DTC is verified by the obtained results.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권5호
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• pp.650-656
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• 2016

Voltage controlled oscillator (VCO) is widely used circuit component in high-performance microprocessors and modern communication systems as a frequency source. In present work, VCO designs using the different combination of NAND gates with three transistors and CMOS inverter are reported. Three, five and seven stages ring VCO circuits are designed. Coarse and fine tuning have been done using two different supply sources. The frequency with coarse tuning varies from 3.31 GHz to 5.60 GHz in three stages, 1.77 GHz to 3.26 GHz in five stages and 1.27 GHz to 2.32 GHz in seven stages VCO respectively. Moreover, for fine tuning frequency varies from 3.70 GHz to 3.94 GHz in three stages, 2.04 GHz to 2.18 GHz in five stages and 1.43 GHz to 1.58 GHz in seven stages VCO respectively. Results of power consumption and phase noise for the VCO circuits are also been reported. Results of proposed VCO circuits have been compared with previously reported circuits and present circuit approach show significant improvement.