• E2M - 전기 전자와 첨단 소재
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• 제10권4호
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• pp.334-341
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• 1997

Streaming electrification on insulating paper and pressboard under D.C. and A.C. electric field was investigated by using paper tubes and oil circulation apparatus. At first, flowing of static charges as measured with no electric field. As the temperature of oil increased, the measured current curve hows peak. As the velocity increased, it shows increasing exponential curve. Then, we applied A.C. and D.C. electric field on paper tube and the current from relaxation tank to earth was measured, which other factors such as temperature and velocity were varied like case of no electric field. The ions in oil carry the charges. So electric field makes asymmetry effect, and electrophoretic effect on ions in oil. We find that as the electric field intensity increased, the charges which were made by electric double layer were increased. The charge vs. velocity curve made peak point at a velocity.

• Journal of Electrical Engineering and Technology
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• 제1권4호
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• pp.528-533
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• 2006

Electrical discharges may occur in gas, liquid as well as solid insulating materials. This paper describes the investigation results on the discharges in air, silicone oil and low density polyethylene (LDPE) using needle plane electrode system under AC voltage of 50 Hz. The experimental results showed that for discharge in air (corona), discharge pulses were concentrated around the peak of applied voltage at negative half cycle. For silicone oil positive as well as negative discharges were observed which concentrated around the peak of applied voltage. The positive pulse number was smaller but the magnitude was higher than that of negative discharge. Discharges in void took place at wider range of phase of applied voltage. The unbalance in pulse number and magnitude similar to that of oil discharges were observed. For electrical treeing in LDPE, the discharges were spread before the zero cross of the applied voltage up to the peak at both positive and negative half cycles. The discharge pulse sequence analysis indicated that the PD occurrence in air, oil and void were strongly affected by the magnitude of applied voltage. However, for electrical treeing it was observed that the discharge occurrence was strongly affected by the time derivative of the applied voltage (dv/dt).

• 한국전기전자재료학회논문지
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• 제25권9호
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• pp.727-731
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• 2012

This paper dealt with the measurement and analysis of electromagnetic waves radiated from a partial discharge (PD) source in insulation oil to apply condition monitoring of oil-immersed transformers. Two types of narrow-band monopole antennas with the resonant frequency of a 500 MHz and a 1 GHz were designed and fabricated. Also, a needle-plane electrode system was manufactured to simulate PDs and the curvature radius of the needle is 10 ${\mu}m$ and the diameter of the plane is 60 mm. Electromagnetic wave was measured by the PD measurement system with the monopole antennas. Detection sensitivity of the fabricated antenna was compared for the same PD magnitude; 620 $mV_{peak}$ for the 500 MHz antenna and 960 $mV_{peak}$ for the 1 GHz antenna to the PD magnitude of 74 pC. Consequently, the 1 GHz monopole antenna is more effective to detect PDs in oil-immersed transformers.

• 한국조명전기설비학회지:조명전기설비
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• 제6권5호
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• pp.50-56
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• 1992

This paper presents the effect of moisture and dust on streaming electrification in transformer oil, in order to investigate the electrification tendency of oil adding moisture an dust. Authors designed series electrification device to analyse streaming electrification phenomena easily. Experimental results show that the streaming current is linearly increased with oil velocity and it has a peak value at about a 50 [%]. Adding of moisture and dust in oil decreased charging level and it was dominant in case of moisture.

• Natural Product Sciences
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• 제7권4호
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• pp.120-123
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• 2001

To develop systems for economic production of useful essential oil compounds, callus was induced from the seedlings of Agastache rugosa and cultured on MS medium. The volatile oil fraction was extracted from the callus and investigated by mean of GC-MS. The composition of the oil was compared with that of the mother plant. As a result, sixty five compounds including ferruginol were identified in the essential oil fraction. The main component of the oil from the leaves of Agastache rugosa was methyl chavichol (53.6%). Methyl jasmonate and jasmonic acid were added to the culturing cell suspension, separately and the composition of induced oil were compared. The oils from cultured cells treated with jasmonates showed considerably different patterns. Especially, the peak of estragole was found in callus oil after treatment with methyl jasmonate as though the amount was limited to 0.58%. In general, the TIC pattern of GC-MS of the callus oil became more similar to the oil from the leaves after elicitation.

• 한국식품영양과학회지
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• 제33권7호
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• pp.1175-1179
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• 2004

Scale-up하기 위하여 24시간동안 1：2：2의 몰 비율로 stirred-batch type reactor에서 합성된 재구성지질은 capric acid와 CLA를 각각 4.9 mol%와 4.1 mot% 함유하였다. 기능성 지방산인 capric acid와 CLA는 주로 TAG의 sn-1,3 position에 분포하였고, sn-2 position에는 linoleic acid가 대부분을 차지하였다. 재구성지질과 대두유의 요오드가는 각각 126와 114이었고, 비누화가는 각각 190과 194로 측정됨으로써, 재구성 지질의 TAG에서 capric acid의 함유를 확인할 수 있었다. 대두유와 재구성지질의 tocopherol함량은 각각 74.6 mg/100 g과 18.2 mg/100 g으로, 재구성지질의 tocopherol 함량은 대두유보다 약 76% 감소하였다. 색도분석 결과, 재구성 지질과 대두유간에 백색도(L＊)와 적색도(a＊)에서는 유의적 차이가 없었으나(p＜0.05),황색도(b＊)에서 재구성지질이 대두유보다 좀더 yellowness를 보이며 유의적 차이를 보였다. (p＜0.05). Reversed-phase HPLC 분석 결과, 재구성지 질에서 capric acid를 함유하고 있는 TAG형태의 partition number (PN)는 25∼37로 약 12.57 area%이었음을 확인하였다. 대두유의 주된 crystallization peak는 -57.86$^{\circ}C$C이었으나, capric acid를 4.9 mol% 함유하고 있는 재구성지질의 crystallization peak는 -52.78$^{\circ}C$로 대두유보다 결정화가 좀더 고온에서 일어났다.

• Tribology and Lubricants
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• 제33권1호
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• pp.23-30
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• 2017

The electric controlled marine diesel engine has fuel pump generating the high pressurized fuel for fuel injection to combustion chamber via a common rail. Fuel pump consists of a cam-roller system. Journal bearing installed between a roller and a cam-roller pin is subjected to fluctuating heavy and instant loads by cam lift. First, Kinematic analysis is carried out to predict bearing loads during one cycle acting on the journal bearing. Second, flexible multi-body dynamic analysis and transient elasto-hydrodynamic(EHD) lubrication analysis for journal bearing considering elastic deformation of cam-roller pin, roller and bearing are conducted using AVL EXCITE/PU software to predict lubrication performance. The clearance ratio and journal groove shape providing lubrication oil are important parameter in bearing design having good performance and can be changed easier than other design parameters such as diameter, width, oil supply pressure and bearing material grade. Generally, journal bearing performance is represented by the minimum oil film thickness(MOFT) and peak oil film pressure(POFP). As well as the traditional design parameters(MOFT, POFP), in this study, temperature rise of lubrication oil is also evaluated through the side leakage flow of supplied oil. By the evaluating MOFT, POFP and temperature rise, the optimum bearing clearance ratio is decided.

• KSBB Journal
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• 제11권6호
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• pp.654-662
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• 1996

원유에 대한 분해능이 있는 균주를 분리하고, 이들 균주의 균체생육과 유화활성 및 원유 전환율을 검토하여 4균주 즉, A54, H17, H17-1 그리고 F6 를 선멸하였다. 이들 균주중 H17-1 균주를 최종선멸하여 형태학적 빛 생화학적 그리고 생리학적 특성 을 조사한 후 Nocardia sp. H 17-1로 명명하였다. Nocardia sp. H17-1의 배양 시간에 따른 균체생육, 유화도 그리고 원유 전환율을 측정한 결과, 균체수 는 $9.1\times109 CFU/mL$었고, 유화활성과 원유 전환율 은 각각 480 unit/mL와 약 83%로서 최대치에 도달하였다. 또한, 다양한 탄화수소를 탄소원으로 이용 하였다. 원유분해를 위한 배양조건 및 환경인자의 영향을 조사한 결과 배양온도는 $^30{\circ}C$, 초발 pH는 7.0, 염분농도는 2.0%이며, 5% 이상에서는 유화활 성이 현저히 감소하였다. 원유농도는 3%, 무기염류 의 농도는 12.5 mM $NH_4N0_3$, 0.057 mM $K_2HPO_4$로 나타났다. 또한, 잔류 원유의 GC 분석 결과 CI6(n­ hexadecane) 이상의 n-alkane peak가 현저히 감소하였다.

• 한국화재소방학회논문지
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• 제28권4호
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• pp.14-20
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• 2014

본 연구는 인화성 액체를 특정 용기에 담유하고 구획된 공간에서 연소 실험을 실시하여 연소 패턴을 분석하는 데 있다. 담유 실험에 사용된 용기는 깊이 20 mm, 넓이 150 mm의 플라스틱이다. 화염이 착화되어 연소되는 과정은 디지털카메라(digital camera) 및 비디오카메라(video camera)를 이용하여 확보하였다. 화염이 최성기에 도달하는 속도는 벤젠이 가장 빠르고 약 60 s이다. 반면 가장 늦게 것은 알코올이었으며 약 360.0 s로 6배 정도 차이가 있었다. 화염이 최성기에 도달하였을 때 플라스틱 용기와 인화성 액체가 동시에 연소됨에 따라 연기는 대부분 검정색이었다. 연소가 완료된 후유증 검지관(crime investigation tube)을 이용하여 유증을 조사한 결과 대두유를 제외한 모든 인화성 물질에서 유증 채취가 가능했다. 즉, 연소 물질의 종류에 따라 화재의 확산 속도 및 패턴 등에 큰 차이가 있다는 것을 알 수 있었다.

• 한국철도학회지
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• 제9권2호
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• pp.19-24
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• 2006

Green gas emissions Trading System(ETS) came into effect in the Europe last year 2005. All transport modes have tried to reduce green gas emission and EU member countries are promoting the use of environmental friendly transport mode to avoid economic loss due to green gas emission. Besides ETS, rapidly rising of oil price and peak oil urge to invest more in the environmental friendly public transport mode and to discourage the use of private cars. The operation of KTX is estimated to bring external cost reduction up to 570 bil. won in 2004 based on European external unit costs of transport modes. This result implies that the expansion of high speed rail network and reconsideration of East-West high speed rail network which is not considered because of weak economic validity is required.