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정재갑,김규태,류권상,정기수 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.1
This paper describes a method to determine absolutely the dissipation factor (DF) of a capacitor connected with resistor in series that doesn’t depend on any reference capacitor with a known DF. The principle of the absolute determination is based on “elimination” of the DF of a reference capacitor by subtracting DF readings from two successive measurements. This method was applied to the calibration of DF in the range 5x10-6 to 1x 10-2 at voltages up to 1 kV. Results obtained using this method were confirmed by comparing them with DF obtained using different methods
청소년 스마트폰 과의존에 미치는 영향과 보호에 관한 연구 -사회적지지, 대인존재감, 사회적 기술을 중심으로
정재갑,변상해 인문사회 21 2018 인문사회 21 Vol.9 No.6
The purpose of this study is to examine the factors which affect adolescents’ over-dependence on smartphones and analyze the causes. The study discusses the prevention and remedy of mobile dependence and practical ways to promote adolescents’ mental health. As a result, it is suggested that adolescents should strengthen their competencies. To increase and restore competencies, it is necessary to develop social support, social presence, and social skills. While there are psychological, behavioral, and physical problems caused by smartphone over-dependence as adverse effects of information-oriented society, this study provides implications to minimize damages by dependency on smartphone use and to prevent them. 본 연구는 청소년들의 스마트폰 과의존에 미치는 영향과 그 원인을 분석하는데 목적이 있다. 연구 내용으로, 청소년을 위한 스마트폰 과의존 예방 및 치료와 정신건강 증진과 이를 위한 실천적 개입 방안에 대해 논의하였다. 연구결과, 청소년들의 스마트폰 과의존과 관련하여 개인의 내적인 차원과 환경적인 차원에서의 역량을 강화하고, 회복역량의 항목으로 사회적 지지와 대인존재감, 사회적기술 등을 통한 개선방안이 필요함을 제시하였다. 이 연구는 스마트폰 과의존으로 인한 심리적, 행동적, 신체적 영향과 같은 다양한 문제가 초래되는 등 정보화 사회의 역기능적 현상을 바탕으로 과의존 피해를 최소화하고, 예방할 수 있는 방안을 도출하는데 있어 필요한 시사점을 제공할 것으로 기대된다.
전류변성기 비교기와 정밀션트저항을 이용한 전류변성기용 부담의 평가기술
정재갑,이상화,강전홍,김명수 대한전기학회 2006 전기학회논문지C Vol.55 No.5(C)
- Both ratio error and phase angle error in current transformer(CT) depend critically on values of CT burden. Thus, precise measurement of CT burden is very important for the evaluation of CT. A method for the measurement of CT burden has been developed by employing the portable shunt precise resistor with negligible AC-DC resistance difference less than 10-5. The burden value(value and power factor) can be calculated from resistance and reactance obtained by measuring the change of ratio error and phase angle error caused by the change of shunt resistor. The uncertainty for the method is evaluated and found to be about 2 %.
정재갑,김인규,김규태,백운봉,남승훈 한국물리학회 2021 Current Applied Physics Vol.26 No.-
We introduce a volumetric analysis technique to characterize the solubility of hydrogen dissolved in polymers and its diffusion coefficient by electrical capacitance measurement electrodes to determine the water level in graduated cylinders. This new and simple technique measures the volume of hydrogen released from rubber inside a graduated cylinder after a sample is exposed to high-pressure hydrogen and subsequent decompression. A diffusion analysis program is utilized to determine the total uptake (C0) and diffusivity (D) of hydrogen, which are used to calculate the solubility (S) and permeability (P). This method is applied to spherical rubber samples of nitrile butadiene rubber (NBR), ethylene propylene diene monomer (EPDM), and fluoroelastomer (FKM), which are potential sealing materials for H2 energy infrastructures. C0 follows Henry’s law for all samples. No sample size and pressure dependence is observed for S, whereas an appreciable size dependence for the three rubbers is detected for D. The uncertainty is evaluated by considering uncertainty factors that affect the measurement. The correlation between D and density of rubber is found. The developed method can be utilized as a standard test for the transport properties versus pressure of various polymer membranes regardless of the sample shapes and size.
대장균 트립토판 중합효소 α 소단위체의 응집 형성에 미치는 잔기 173 치환체의 억제 효과
정재갑,박후휘,임운기 한국생명과학회 2022 생명과학회지 Vol.32 No.9
Aggregation of normally soluble proteins can cause disease-related problems. Tryptophan synthase α-subunit (αTS) in E. coli adopts one of most popular structural scaffolds, the TIM barrel fold. Previous mutagenesis of the αTS gene resulted in many aggregation-prone mutant proteins. Here, Y173F (Tyr at residue 173 to Phe) substitution, which imparts increased stability, was tested for its ability to suppress aggregation of aggregation-prone mutant proteins (Y4C, S33L, P28L, P28S, G44S, D46N, P96L, and P96S). Aggregation was suppressed in all eight severe aggregate-forming mutants (all differing in their mutation positions), by the Y173F replacement. P28L αTS, which was available in pure form, was further analyzed and showed reduced secondary structure content, lower stability, and a looser structure with more exposed hydrophobic surface compared to the wild type protein. A double mutant P28L/Y173F protein showed almost no indication of these changes compared to the wild type protein. We hypothesized that Tyr at position 173 in αTS is positioned at the hydrophobic core and may serve to suppress the aggregation of this protein caused by other residues. Important residue (s) could be working widely in the prevention/suppression of protein aggregation.
정재갑,권성원,이상화,강전홍,김명수,한상길,김윤형,한상옥 대한전기학회 2008 전기학회논문지 P Vol.57 No.2
- National standard system for calibrating voltage transformer(VT) up to primary voltage of 240 kV have been established in 2005. The system consists of voltage source, regulating unit, VT testing unit, standard VT, VT under test and VT burden. To verify and validate the performance for 240 kV VT calibration system, the comparison with the National Measurement Institute of Australia(NMIA) has been performed using same VTs. The comparison results of the VTs mesured at the Korea Research Institute of Stansdards and Science(KRISS) are consistent with those measured at NMIA within 0.002 % for ratio error and 0.14 min for phase displacement in the primary voltage ranges of Vp = 3300 V - 22000 V with a secondary voltage of Vs = 110 V.
정재갑,문영일,정기수,김규태 한국고분자학회 2020 Macromolecular Research Vol.28 No.6
To characterize the dielectric relaxation embedded in polymers, we developed a program algorithm that analyzes the relaxation processes from dielectric permittivity versus frequency data based on governing functions such as the Havriliak-Negami function including the conductivity contribution. With the help of the developed simulation program, we have identified three processes: an α process due to rotational and segmental motions of the C-C bond, an α' process attributed to the fluctuation of the end-to-end dipole vector of the polymer chain, and the conduction contribution observed at high temperatures and low frequencies. The activation energy and glass transition temperature for the two main relaxations were independently determined from both the imaginary permittivity versus frequency and temperature by assuming Arrhenius dependence and the Vogel-Fulcher-Tamman law. The results obtained by the two methods for α and α' relaxations were compared with each other and with that obtained by differential scanning calorimetry.