• Journal of Electrical Engineering and Technology
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• 제12권3호
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• pp.1007-1015
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• 2017

This paper proposes a new control technique of energy storage system (ESS) for smoothing the active power of renewable energy sources (RES) such as photovoltaic and wind turbine generation. As the penetration of RES into grid increases, it is difficult to maintain the permissible level of power quality, that is, voltage and frequency fluctuation in power systems. To solve this problem, ESS control methods using low pass filter (LPF) have been proposed for mitigating the fluctuation of RES output. However, those have a lot of drawbacks which need to be supplemented. Hence, this paper presents the improved active power control with additional reactive power control for maintaining power quality properly. The proposed method minimizes the capacity of ESS to be required for smoothing RES output fluctuation through mitigation of phase delay problem in LPF. In addition, the voltage regulation improves by using additional reactive power control. The proposed method was verified through simulation analysis using PSCAD/EMTDC.

• 한국재난정보학회 논문집
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• 제19권4호
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• pp.984-992
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• 2023

연구목적: 본 연구의 핵심 문제는 국내 발파 작업에 대한 구체적인 소음규제 기준이 없다는 점이다. 현재 국내의 발파작업 소음규제 기준이 별도로 제정되지 않고 일일생활소음 기준인 70데시벨에 10데시벨 보정하여 80데시벨의 소음규제 기준을 갖고 있다. 대조적으로 많은 외국에서는 발파작업에 특별히 맞춰진 별도의 소음규제 기준을 갖고 있다. 이에 국내외 발파작업 소음규제 기준을 비교하여 국제적인 합리적 발파소음 기준을 제시하고자 한다. 연구방법: 국내외 소음규제 기준을 비교 분석한 것으로 유추할 수 있다. 현행 국내의 발파작업시 소음규제 기준과 미국, 영국, 호주, 일본 및 중국 등의 발파작업시 소음규제 기준에 관한 데이터 수집 및 분석을 한다. 연구결과: 국내 건설현장의 발파작업시 소음규제 값은 별도로 제정되지 않아 발파소음의 특정, 특성에 적절하게 맞춰져 있지 않은 것으로 나타났다. 해외의 경우 발파작업시 소음규제 값에 대해 생활소음 규정 등을 일률적으로 적용하는 것은 보다 안전하고 효율적이며 친환경적인 발파공법을 적용할 수 있도록 현실적인 소음규제 값을 제정 하였다. 결론: 국내외 비교 연구한 내용과 같이 합리적인 발파작업시 소음규제 값을 제정하여 발파안전 기준을 잘 준수하여 효율적이며 경제적이고 친환경적인 발파공법의 도입을 방해하지 않고 널리 채택되기를 바란다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.637-644
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• 2006

Acceleration time history used in the seismic analysis of nuclear porter plant structure should envelop a target power spectral density (PSD) function in addition to design response spectrum. Current regulation guide defines the target PSD function only for the U.S. URC RG 1.60 Design Response Spectrum. This paper proposes a technical scheme to obtain the target PSD function compatible with generally defined design response spectrum. The scheme includes the methodology for design-spectrum compatible motion history in order to minimize the variation of the derived target PSD function. The PSD calculation procedure follows simple and practical methods allowed within regulation. Effectiveness of the proposed scheme is identified through an example problem. The design response spectrum In the example is based on U.S. NRC RG 1.60 but amplifies the spectral acceleration amplitudes above 9Hz. The target PSD function with little variation can be constructed with the reduced time history ensemble.

• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1261-1268
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• 2013

This study proposes a voltage and reactive coordinative control strategy with distributed generator (DG) in a distribution power system. The aim is to determine the optimum dispatch schedules for an on-load tap changer (OLTC), distributed generator settings and all shunt capacitor switching on the load and DG generation profile in a day. The proposed method minimizes the real power losses and improves the voltage profile using squared deviations of bus voltages. The results indicate that the proposed method reduces the real losses and voltage fluctuations and improve receiving power factor. This paper proposes coordinated voltage and reactive power control methods that adjust optimal control values of capacitor banks, OLTC, and the AVR of DGs by using a voltage sensitivity factor (VSF) and dynamic programming (DP) with branch-and-bound (B&B) method. To avoid the computational burden, we try to limit the possible states to 24 stages by using a flexible searching space at each stage. Finally, we will show the effectiveness of the proposed method by using operational cost of real power losses and voltage deviation factor as evaluation index for a whole day in a power system with distributed generators.

• 조명전기설비학회논문지
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• 제29권7호
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• pp.28-37
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• 2015

Owing to the variability of large-scaled wind power system, the development of wind farm management technologies and related compensation methods have been receiving attention. To provide an accurate and reliable output power, certain wind farm adopts a specified management system including a wind prediction model and grid expectation solutions for considering grid condition. Those technologies are focused on improving the reliability and stability issues of wind farms, which can affect not only nearby system devices but also a voltage condition of utility grid. Therefore, to adapt the develop management system, an expectation process about voltage condition of Point of Common Coupling should be integrated in operating system for responding system requirements in real-time basis. This paper introduce a grid imposing method for a real-time based wind farm management system. The expected power can be transferred to the power flow section and the required quantity about reactive power can be calculated through the proposed system. For the verification process, the gauss-seidel method is introduced in the Matlab/Simulink for analysing power flow condition. The entire simulation process was designed to interwork with PSCAD for verifying real power system condition.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.246-247
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• 2010

This paper deals with the water treatment of the leachate from sewage filled ground by a pulsed power technology. Leachate from sewage filled ground should be treated below regulation level of COD in order to prevent environmental pollution and usually treated by a chemical method. Among the pollutants mixed in the leachate, chemical compounds of benzene series are known to be difficult to break down, and need to use high cost treat methods. The treatment of the benzene compounds by high power pulsed power supply was studied. For the high-rate, cost-effective treatment of leachate, pulsed power supply should have high repetition rates and require switching devices of long lifetime. In order to meet the demands of the above condition, pulsed power generator based on semiconductor switches using IGBTs as primary switches were developed. The experimental results verified that benzene compounds can be treated effectively by high voltage electric pulses, and this fact indicates that the treatment method by pulsed power source is a promising substitute.

• 전기전자학회논문지
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• 제5권2호
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• pp.146-152
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• 2001

본 논문에서는 배전 계통에서 전압 파형 개선을 위하여 배전용 정지형 보상기(DSTATCOM)의 제어 기법 2가지를 보였다. 1선 지락 사고 시에 제시한 방법을 이용한 시뮬레이션을 통해 선로 전압 파형이 개선됨을 알 수 있다. 또한 비제어 및 PI 제어와 LQR 제어를 비교하였다. 요구되는 응답 특성 및 제어 효과에서 LQR 제어가 우수함을 보이고 PSCAD/EMTDC을 이용하여 검증하였다.

• Physical Therapy Rehabilitation Science
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• 제11권3호
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• pp.376-383
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• 2022

Objective: This study investigated how social support and self-efficacy affect the quality of life of elderly people with chronic diseases. Design: The study consisted of descriptive survey research. Methods: A questionnaire covering social support, self-efficacy, and quality of life was distributed to 320 elderly people with chronic diseases. Pearson's correlation analysis was performed to examine the correlation between the respondents' social support (family support, friend support, medical support), self-efficacy (confidence, self-regulation efficacy, preference for task difficulty), and quality of life. Multiple regression analysis was also performed to identify the factors affecting the respondents'quality of life. Results: "Friend support" and "quality of life" (r=-636, p<0.001), had a negative correlation, "confidence" and "quality of life" (r=0.827, p<0.001), "self-regulating efficacy" and "quality of life" (r=0.736, p<0.001), and "preference for task difficulty" and "quality of life" (r=0.295, p<0.001)-had positive correlations. Friend support (𝛽=-0.164, p<0.001), confidence (𝛽=0.592, p<0.001), and self-regulation efficacy (𝛽=0.160, p<0.001) were found to affect quality of life. The independent variables showed the following degrees of influence, in order: confidence, friend support, and self-regulation efficacy. Their explanatory power was 73.3% (F=146.844, p<0.001). Conclusions: The quality of life of elderly people with chronic diseases can be improved by formulating health-promotion programs that foster a sense of community.

• 한국보육지원학회지
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• 제18권4호
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• pp.1-16
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• 2022

Objective: The purpose of this study is to test the psychometric properties of the Maternal Emotion Coaching Questionnaire (MECQ, Lim et al., 2018) in order to measure emotion coaching in mothers of preschoolers. Methods: A total of 316 preschoolers and their mothers participated in this study. Maternal emotion coaching was assessed by self-report and child emotion regulation ability was evaluated by the teacher. Data were analyzed with chi-square tests, reliability analysis, confirmatory factor analysis, latent profile analysis, and F-test. Results: Each item of the MECQ showed proper discriminative power. The MECQ and each subscale demonstrated adequate internal consistency and split-half reliability. Evidence of construct validity was provided by confirmatory factor analysis. The five-factor model including maternal attention, awareness, acceptance, empathy, and guidance showed a good fit. Results of the latent profile analysis revealed three profiles of emotion coaching: excellent, good, and poor. Preschoolers with mothers in the poor coaching profile showed significantly lower emotion regulation ability compared to those in the excellent or good coaching profiles, which suggested discriminative validity of the MECQ. Conclusion/Implications: The MECQ presents a reliable and valid tool to assess emotion coaching in mothers of preschool children and can thus be effectively used for mothers of preschoolers.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1024-1026
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• 2002

The active power filter(APF) is a good solution for elimination of harmonics, which is produced by the nonlinear loads such as static power converter, computer and so on. Our trademark of APF is a POSAPF-series, which was applied to Samsung Electronics corp, in January 2002, and which lines up from 50A to 500A. This equipment reduces total demanded distortion (TDD) by 2${\sim}$3%, which originally 11${\sim}$13%. This paper discusses the harmonic regulation, measurement and analysis, and describes control theories and design methods of POSAPF-series, and, finally, shows the experimental results of a real system.