• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권10호
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• pp.431-435
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• 2003

It is very difficult and dangerous to measure PD(Partial Discharges) from high voltage equipments in outdoor situation. But that is very important thing for preventing them from more serious accident by defects made by insulating degradation. This paper provides useful method to detect PD signals easily without any dangerous situation. Electric field sensor by the principle of capacitor can detect PD signals without direct connection between sensor and high voltage equipment and has very wide frequency range suitable for noise rejection. Electric field sensor and related circuit for processing PD signal show good performance as a PD sensor when it is applied to simulated high power equipment generating PD pulses.

• 한국농림기상학회지
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• 제2권4호
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• pp.183-189
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• 2000

한반도 낙엽활엽수림의 우점종으로 대표되는 졸참나무(Quercus serrata), 신갈나무(Q. mongolica), 굴참나무(Q. variabilis)의 종자 발아 및 성장관계 실험에서 다음과 같은 결론을 도출하였다. 도토리 중량이 무거운 굴참나무가 초기 성장력에서 다른 두 수종에 비해 왕성하였고, 이는 도토리 중량이 참나무류 초기 성장에 지대한 영향을 미치는 것으로 파악되었다. 참나무류의 하야지(夏芽枝, Lammas shoot)형성과 묘고(苗高)생장에서 세 수종 모두 RLI(relative light intensity) 20%에서 RLI 52%에서 보다 높은 하야지 형성을 및 탁월한 신장생장을 나타냄으로써 상당히 강한 내음성을 보여주었다. 본 실험광도의 조건에서 광도의 증가는 세 수종 모두에서 다른 성장인자 보다 근원경(根元經) 및 주근(主根) 측근(側根)의 발달을 더욱 더 촉진 시켰고, 개체당 엽면적 중량지수(mg/$cm^2$)의 증가로 나타나 음엽에서 점점 양엽의 특성을 보여주었으며, 개체당 엽면적 생산성지수(mg/$cm^2$)는 점점 높아져 단위 엽면적당 전 건중량이 더욱 증가함을 보여주었다. 엽(엽)의 성분분석에서는 광도의 증가로 잎의 질소(N), 인(P), 칼륨(K) 함량은 낮아지고, 토양수분의 증가는 잎의 인(P), 칼륨(K), 칼슘(Ca), 마그네슘(Mg)의 함량을 높여 주었다. 이상의 결과에서 참나무류의 천연갱신을 위한 작업법으로 초기에는 모수(母樹)의 보호아래 나지(裸地)의 20-30% 광도 수준으로 산벌갱신(傘伐更新)작업법이 추천되며, 소나무와 혼효림 조성을 위한 군상작업(群狀作業)에서도 내음성이 비교적 강한 참나무류를 음지쪽에, 소나무는 양지쪽을 택하여 천연 갱신을 유도한다면 좋은 결과를 얻으리라 사료된다.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권1호
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• pp.1-4
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• 2004

This paper presents an investigation of the phase-resolved partial discharge (PD) pattern of PET (Poly Ethylene Telephthalate) films with carbon black particles. The phase-resolved PD pattern and statistical parameter from PET samples according to the number of included semiconductor particles were measured. The measurement system consisted of a conventional PD detector using a digital signal processing technique. The partial discharge patterns of the PET films that include the semiconductor particles were investigated to simulate an actual situation that may exist in the cable. In addition, difference of PD patterns between semiconducting particles in PET films and artificial voids was studied. The relationship between the numbers of semiconductor particles in PET films was discussed through the difference of Ψ-q-n distribution and statistical analysis.

• 한국약용작물학회지
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• 제28권1호
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• pp.1-8
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• 2020

Background: This study was conducted to investigate the effects of NaCl concentration on the photosynthetic parameters, chlorophyll fluorescence and growth characteristics of Crepidiastrum sonchifolium. Methods and Results: As treatments, we subjected C. sonchifolium plants to four different concentrations of NaCl (0, 50, 100 and 200 mM). We found that the photosynthetic parameters maximum photosynthesis rate (P_{N max}), net apparent quantum yield (Φ), maximum carboxylation rate (V_cmax), and maximum electron transport rate (J_max) were significantly reduced at an NaCl concentration greater than 100 mM. In contrast, there was an increase in water-use efficiency with increasing NaCl concentration, although in terms of growth performances, leaf dry weight, root dry weight, stem length, and total dry weight all decreased with increasing NaCl concentration. Furthermore, leakage of electrolytes, as a consequence of cell membrane damage, clearly increased in response to an increase in NaCl concentration. Analysis of the polyphasic elevation of chlorophyll a fluorescence transients (OKJIP) revealed marked decrease in flux ratios (Φ_PO, Ψ_O and Φ_EO) and the PI_abs, performance index in response to treatment with 200 mM NaCl, thereby reflectings the relatively reduced state of photosystem II. This increase in fluorescence could be due to a reduction in electron transport beyond Q^-_A. We thus found that the photosynthetic parameters, chlorophyll fluorescence and growth characteristics of C. sonchifolium significantly increased in response to treatment with 200 mM NaCl. Conclusions: Collectively, the findings of this study indicate that C. sonchifolium shows relatively low sensitivity to NaCl stress, although photosynthetic activity was markedly reduced in plants exposed to 200 mM NaCl.