• 전기학회논문지
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• 제59권9호
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• pp.1644-1651
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• 2010

VLF $tan{\delta}$ diagnosis technology is introduced in IEEE Std 400 and proposed as evaluation criterion in an effective way of detecting water tree which mainly causes the failure of XLPE insulated cables. In order to inspect the accuracy of the VLF $tan{\delta}$ method for XLPE insulated power cables in Korean distribution system, diagnosis for 41 cables which were being serviced in the fields has been carried out and they were removed for AC breakdown voltage test after. Regarding the 41 cables, it was hard to confirm any relation between the VLF $tan{\delta}$ values and AC breakdown voltages and also water tree in the insulation was not detected. However, the other cables were failed several days after the diagnosis of the 41 cables. Water trees were found and their VLF $tan{\delta}$ values were also much higher than the criterion of IEEE standard. It has been ascertained that we need to change the IEEE criteria in order to improve the accuracy of detecting water trees by additional analyzing of field examples of failure and case studies from overseas countries and therefore amended VLF $tan{\delta}$ test voltage and evaluation criteria have been proposed.

• 감성과학
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• 제21권3호
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• pp.73-82
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• 2018

경쟁과 협력을 인식하는 것은 일하는 공간에서 상호작용 디자인을 하는 데에 필요한 요소이다. 본 연구는 타인과의 상호작용에서 유발되는 경쟁과 협력의 사회 감성을 심장의 생리 반응 패턴으로 객관적이고 정량적으로 인식하는 방법을 개발하는 것이 목적이다. 피험자 60명은 패턴 게임으로 구성된 과제로 경쟁-협력 실험에 참여하였고 심전도를 측정하였다. 심전도로부터 시간 영역 지표인 RRI와 SDNN, pNN50, rMSSD를 추출하였고, 주파수 영역 지표인 VLF와 LF, HF, VLF/HF, LF/HF, lnVLF, lnLF, lnHF, lnVLF/lnHF를 추출하였다. 독립 표본 t검정으로 사회 감성에 따라 추출한 지표들의 통계적 유의성을 확인하였다. 통계적으로 유의한 지표들로 단계적 판별 분석을 진행하여 선정된 SDNN, VLF, lnVLF/lnHF 지표로 경쟁-협력 규칙을 정의하고 검증하였다. 검증 결과 85%의 인식 정확도를 보였다. 본 연구에서 제안한 감성 인식 방법은 다양한 분야에 접목되어 사용자 맞춤형 서비스 제공에 활용될 수 있을 것이라 생각된다.

• 동의신경정신과학회지
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• 제23권3호
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• pp.47-62
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• 2012

Objectives : This study is to figure the relations of the heart rate variability, body component analysis and accompanying symptoms of 350 insomnia patients. Methods : For this study we evaluated Heart Rate Variability(HRV) and body component analysis on 350 insomnia patients who visited Dongeui oriental hospital of Dongeui university from January 2008 to March 2012. The accompanying symptoms was collected based on each patient's progress note. Results : 1. There was no difference between PR, LF and VLF of male and female groups. HF was higher in the patients' of female group and LF/HF ratio was higher in the male group. The patients' group of age under 39 had higher HF, LF, VLF and LF/HF ratio than the group over 39. 2. The average of LF was the smallest, and the average of VLF was in the middle, while the average of HF was the largest. 3. Regarding patients' age and gender, as the patients' age increased, their HF, LF, VLF and LF/HF ratio decreased significantly. HF, LF, VLF, and LF/HF ratios were, however, independent on the patients' gender. As the patients' age increased, their BMI increased, while the patients' gender did not affect on their BMI. The amount of visceral fat increased with the patients' age, but wasn't dependent on the patients' gender. 4. As the patients' BMI increased, PR and LF decreased. As the patients' amount of visceral fat increased, PR, HF, LF and VLF decreased. 5. The most frequent accompanying symptoms of the insomnia patients was headache. Neither HF nor LF/HF ratio was dependant on any of the accompanying symptoms. Patients with anxiety showed significantly higher LF than those without anxiety. Patients with fatigue and physical pain showed significantly higher VLF than those without either of them. Conclusions : The study showed that as the insomnia patients age increased, the HF, LF, VLF, LF/HF ratio significantly decreased, but the BMI and visceral fat increased. The HF, LF, VLF, LF/HF ratio BMI, or the visceral fat was independent on the gender. As BMI increased, PR and LF decreased. As visceral fat increased, PR HF, LF and VLF decreased. Patients presenting anxiety had higher LF. Patients either with fatigue or physical pain had higher VLF. Neither HF nor LF/HF ratio had any significant correlation with any of the accompanying symptoms.

• 지질공학
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• 제9권1호
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• pp.59-68
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• 1999

단층의 존재 가능성과 파쇄대에 대한 지전기적 구조를 밝히기 위하여 양산단층 남부 상천리 지역에 대하여 전기 비저항 탐사(쌍극자 탐사)와 VLF 탐사를 수행하였다. 양산탄층 추정선을 가로질러 4개의 측선에 걸쳐 실시한 전기 비저항 탐사 결과 단층선을 경계로 주로 동측에는 고비저항대가 서측에는 저비저항대가 나타난다. 이는 수직운동성분이 포함된 주향이동 단층운동에 의해 동측 기반암 블록이 상대적으로 상승한 결과로 사료된다. 파쇄대와 밀접하게 관련되어 나타나는 VLF 자료의 0점 통과점과 지전기적 저-고 비저항대 경계부는 양산단층의 제 4기 단층운동 추정선과 거의 일치하게 나타난다. 저비저항대가 지표에서 거의 수직으로 나타나는 것으로 보아 본 연구 지역의 예상 단층선을 통과하는 양산단층은 단층 양측이 10m 이상의 기반암의 깊이 차이를 나타내며 고각의 경사를 지닌 단층으로 추정된다.

• 지구물리와물리탐사
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• 제8권2호
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• pp.184-190
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• 2005

VLF 주파수 평면파에 대한 지하의 반응을 지배하는 요소들을 물리적으로 간단히 설명하고자 하였다. VLF 법은 비록 탐사심도나 사용 주파수의 제한과 같은 심각한 단점들도 있지만, 지금까지 가장 흔하게 사용되어 온 전자탐사법으로 장점 또한 대단히 많다. 자기장 측정 모드의 경우 가볍고 값싼 장비 덕분에 넓은 영역에서 지하의 전도체를 신속하게 탐사하는데 유용하다. VLF 법을 전기장 모드에서 적용하면 비록 단순하지만 정략적 해석이 가능하며, 저렴한 장비와 신속한 현장작업이라는 장점 덕분에 개략탐사용으로 탐사 초기에 적합하다.

• 자원환경지질
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• 제29권5호
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• pp.623-627
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• 1996

Combined SP/VLF surveys were carried out at tide embankment, Changgi-ri, Anmyeon-up, Chungcheongnamdo in order to confirm the seawater seepage zone of the embankment using the 128 Channels SP monitor system and VLF/Magnetometer system. These methods were successful in the detection of the seawater seepage zone. The self-potential method can give better resolution of the seepage zone than do VLF method.

• 한국전기전자재료학회논문지
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• 제33권1호
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• pp.1-5
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• 2020

In this study, the objective is to improve the criteria used for statistical comparison of the VLF tanδ (TD) database and failure rate according to water-tree degradation in underground distribution power cables. The aging condition of the KEPCO criteria is divided into 6 levels using the Weibull distribution, and the "failure imminent" condition is quantified by using the statistical end-point of the lifetime parameter of the VLF big-data group obtained from KEPCO. Moreover, new criteria with a 2-dimensional combination of TD, DTD, and a statistical normalized factor are suggested. These criteria exhibit high reproducibility for the detection of cables in an imminent failure state. Consequently, it is expected that the adoption of the extended VLF-2019 criteria will reduce the asset management cost of cable replacement compared to the VLF-2012 criteria of KEPCO.

• International Journal of Industrial Entomology and Biomaterials
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• 제1권1호
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• pp.29-33
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• 2000

We cloned and characterized a very late expression factor 1 gene, vlf-1, which regulates the level of very late gene transcripts, from Bombyx mori nuclear polyhedrosis virus (BmNPV) K1 strain. The 1,140 bp vlf-1 has an open reading frame of 379 amino acid and a MW of 44 kDa. The vlf-1 nucleotide sequence of BmNPV-Kl showed high homology with Autographa californica nuclear polyhedrosis virus and BmNPV T3 strain so far known, and its deduced amino acid residues were identical to those of BmNPV T3. The location of vlf-1 in the BmNPV-Kl genome was confirmed by Southern blot analysis and its expression patterns at the transcriptional level were confirmed by Northern hybridization analysis.

• 한국산학기술학회논문지
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• 제21권8호
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• pp.593-602
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• 2020

국내 공장이나 지중에 설치되어 있는 전력 케이블은 제조과정, 설치, 사용 중의 환경여건에 따라 사고가 발생할 수 있는 필연성을 갖고 있다. 전력 케이블에서 사고가 일어났을 때 막대한 경제적 손실과 사회적 혼란을 야기할 수 있어 이를 미연에 방지하고자 진단을 통한 케이블의 예방관리의 중요성이 증대되고 있다. 이에 본 논문에서는 현장에서 발생 될 수 있는 케이블의 설치나 제조결함, 경년열화로 문제가 될 수 있는 부분을 모의하여 진단시료 케이블을 제작하였고, 최근 도입되어 적용되고 있는 VLF(Very Low Frequency)장비를 사용하여 유전정접(tan 𝛿 ; TD), 부분방전(Partial Discharge ; PD)시험을 실시하였고, 0.1Hz 주파수를 갖는 VLF전원을 가압을 한 후 HFCT(High Frequency Current Transformer)를 이용한 부분방전과 AC(상용주파)내압 장비를 이용하여 가압한 후 PD측정을 수행하였다. 그 결과, VLF를 통한 2.0U₀ 전압에서 B, C상 결함시료에서는 내부 부분방전을 측정할 수 있었으며 A상 정상시료에서는 0.5~2.0U₀ 전압에서 모두 노이즈로 측정되었다. 또한, 상용주파수의 AC(60Hz) 내압장비를 통한 1.5U₀전압에서 측정하여 그 실효성을 검증하였다. 활선상태에서의 부분방전은 1.0U₀의 사용전압에서 측정 되어지며, 장비를 설치할 때 위험성이 있고, AC내압장비는 부피나 무게 등에 의해 이동의 어려움이 있어 사선상태의 VLF를 통한 진단방법이 안전과 실효성이 있음을 알 수 있었다.

• International Journal of Industrial Entomology and Biomaterials
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• 제2권1호
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• pp.19-26
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• 2001

Transformed Spodoptera frugiperda (Sf9) cells expressing baculovirus very late factor (VLF-1) were constructed by using Autograha nuclear polyhedrosis virus (AcNPV) immediate earthy gene (ie1). Neomycin-resistance gene as a selectable marker was introduced under the control of AcNPV ie1 promoter, and Bombyx mori nuclear polyhedrosis (BmNPV-K1) vlf-1 gene was introduced under the control of the Drosophila heat shock protein gene (hspr70) promoter to yield dual expression plasmid with two independent transcription units. It was transfected into Sf9 cells and cell clones expressing vlf-1 were selected by G4l8 treatment. Genomic DNA from transformed cells was isolated and integration of AcNPV iel harboring vlf-1 was confirmed by PCR using AcNPV iel-specific primers and Southern blot analysis. The transformed cells expressing VLF-1 in an infection-independent manner expressed foreign gene product of recombinant baculovirus in the earlier stage of infection compared with control Sf9 cells. These results suggest the possible to develop highly efficient transformed insect cells for baculovirus expression vector system.