• 한국응용과학기술학회지
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• 제24권2호
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• pp.190-195
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• 2007

The transesterifications of beef tallow and the mixture of beef tallow and rapeseed oil were conducted at $65^{\circ}C$ respectively using TMAH, NaOH and their mixed catalysts. The reactants were emulsified with 1vol% emulsifier and propylene glycol. The overall conversion of beef tallow was 95% at such optimum conditions as the 1:8 of molar ratio and 0.8 wt% TMAH. The overall conversion of mixed fat at the 1:8 of molar ratio and mixed catalyst of 70 wt% TMAH 30 wt% NaOH was close to 97% which appeared at 0.8 wt% TMAH in 80min. And the kinematic viscosity of biodiesel mixture using the mixed catalyst was $6.5mm^2/s$ at $40^{\circ}C$.

• Journal of Korean Society for Atmospheric Environment
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• 제18권E2호
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• pp.107-120
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• 2002

Dimethyl sulfide (DMS) is the major sulfur gas released from the ocean. The atmospheric DMS released from the ocean is oxidized mainly by hydroxyl (OH) radical during the day and nitrate (NO$_3$) radical at night to form sulfur dioxide (SO$_2$) as well as other stable products. The oxidation mechanism of DMS via OH has been known to proceed by two channels; abstraction and addition channels. The major intermediate product of the addition channel has been known to be dimethylsulfoxide (DMSO) based on laboratory chamber studies and field experiments. However, a branching ratio for DMSO formation is still uncertain. The reaction of DMSO with OH ultimately produces SO$_2$and dimethylsulfone. The major product of the abstraction channel has known to be SO$_2$from laboratory chamber studies. But overall conversion efficiency for DMS to SO$_2$from DMS oxidation is still inconsistent in the literature. Based on laboratory and field studies, the conversion efficiency from the abstraction channel is likely to be greater than 0.5, while that from the addition channel is likely to be greater than 0.6. Overall conversion efficiency from DMS to SO$_2$might be greater than 0.5 based on the above two values in the remote marine boundary layer (MBL). This high efficiency in the remote MBL is supported by strong coupling between DMS and SO$_2$measurements with high temporal resolution.

• 한국응용과학기술학회지
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• 제27권2호
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• pp.123-128
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• 2010

The continuous transesterification of mixed fat was done on the plug flow reactor packed with the static mixers. The transesterification using 0.5 wt% KOH, 0.8 wt% TMAH and mixed catalyst[40 v/v% KOH(0.5 wt%)+60 v/v% TMAH(0.8 wt%)] was conducted with the changes of molar ratios, weight percentage of beef, flow rates and number of static mixer's elements at $65^{\circ}C$. The overall conversion of mixed fat at 1:8 molar ratio, 50 wt% of beef and 24 of static mixer's elements increased until 0.7mL/min of flow rate. The overall conversion of mixed fat showed 96% at those conditions. So, the optimum operating conditions on tublar reactor were 1:8 molar ratio, 50 wt% of beef, 0.7 mL/min of flow rate and 24 of static mixer' s elements.

• 한국초지조사료학회지
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• 제17권4호
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• pp.399-406
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• 1997

This research was carried out to investigate the effect of zeranol injection on dry matter(DM) and nutrient intake requirement by growth stage of early castrated bull with 3 treatments(bul1, steer, steer+zeranol) with 28 Holstein bull at National Livestock Research Institute. The main results were as follows: DM intake at growing and fatting stage was the highest in steer groups, that the highest in bull groups at finishing stage and overall mean DM intake was 5% lower at steer+zeranol groups compared to bull and steer, respectively. Net energy intake at finishing stage was the highest as 35.49 Mcal at bull groups, while overall mean net energy intake was 101 - 109% of NRC requirement without significant difference. Concentrate intake to body weight was 1.68- 1.82, 1.91 -2.08 and 1.81 -2.05% at growing, fatting and finishing stage, respectively. Overall mean concentrate intake to body weight at steer groups was 1.94%, which is 1.8 and 1.81% higher compared to bull and steer+zeranol groups, respectively. Feed conversion ratio(DM) during overall period was the worst at steer groups as 9.321g, and also net energy conversion ratio was similar to DM conversion ratio.

• Asian-Australasian Journal of Animal Sciences
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• 제11권2호
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• pp.192-195
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• 1998

Biomass conversion efficiencies (B.C.E) of six fish species viz, Catla catla, Labeo, rohita, Cirrhina mrigala, Hypophthalmicthys molitrix, Ctenopharyngodon idella and Cyprinus carpio cultured under artificial feed (T1), broiler manure (T2), buffalo manure (T3), N:P:K (25:25:0) (T4) and control pond (T5) have been determined for the period of one year. The overall biomass conversion efficiencies under the influence of T2, T3, and T4 were statistically similar. However, the best (0.40) efficiency was determined under feed supplement-ation (T1).

• 한국응용과학기술학회지
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• 제23권4호
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• pp.300-306
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• 2006

The esterification of palmitic acid in rapeseed oil and methanol emulsified by propylene glycol with PTSA(p-toluene sulfonic acid) was followed by the transesterification of rapeseed oil into biodiesel with 1(w/v)% GMS(glycerol monostearate) as an emulsifier using TMAH(tetramethyl ammonium hydroxide) catalysts at $60^{\circ}C$. The former reaction was optimized at the 1:20 of molar ratio of oil to methanol and 5wt% PTSA, and the latter was optimized at the 1:8 of molar ratio of oil to methanol and 0.8wt% TMAH. The overall conversion into biodiesel was 98% after 60min of reaction time at the 1:8 of molar ratio, 0.8wt% TMAH and $60^{\circ}C$. TMAH was a good catalyst to control the viscosity of biodiesel mixture.

• 한국응용과학기술학회지
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• 제26권4호
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• pp.394-399
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• 2009

The esterification of palmitic acid in Jatropha Oil using 8wt% p-TSA catalyst was done at the 1:8 molar ratio of oil to methanol and $65^{\circ}C$. The conversion of palmitic acid appeared to be 95.3% in 60min. After that, the continuous transesterification of the oil using 0.5wt% KOH, 0.8wt% TMAH mixed catalyst[40vol% KOH(0.5wt%) + 60vol% TMAH(0.8wt%)] and 1.1wt% TMAH was conducted with the flow rates and the molar ratios at $65^{\circ}C$. The overall conversion of Jatropha Oil increased with the decrease of flow rate and showed 95.6% with 9ml/min of flow rate at the 1:8 molar ratio of oil to methanol and $65^{\circ}C$. But it showed 87% with 15ml/min of flow rate at the same conditions. The recovery of methanol(%) appeared to be 86% at the 1:8 molar ratio of oil to methanol, mixed catalyst and $65^{\circ}C$.

• 한국산학기술학회논문지
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• 제6권6호
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• pp.491-496
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• 2005

본 논문에서는 일명 델타변환 무정전전원장치(UPS)로서 알려져 있는 3상 라인 인터랙티브 UPS 시스템의 성능 시험에 대해서 다루고 있다. 델타변환 UPS는 종래의 단일 변환 라인 인터랙티브 UPS 시스템에서 직렬 인덕터를 제거하고 직렬 및 병렬 PWM(Pulse Width Modulation) 컨버터를 사용하는 새로운 라인 인터랙티브 UPS 시스템으로 전원 전류를 직접 제어함으로써 UPS 시스템의 입출력 특성들이 상당히 개선되는 것으로 알려져 있다. 여기서는 UPS 시스템의 성능 시험에서 중요한 내용들인 부하시험, 정전/복전시험, 동기절체 시험 등에 대한 결과들을 제시하고 델타변환 UPS 시스템에 대한 전반적인 평가를 한다.

• 전력전자학회논문지
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• 제17권1호
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• pp.34-40
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• 2012

In this paper, voltage clamped tapped-inductor boost converter with high voltage conversion ratio is proposed. The conventional tapped-inductor boost converter has a serious drawback such as high voltage stresses across all power semiconductors due to the high resonant voltage caused by the leakage inductor of tapped inductor. Therefore, the dissipative snubber is essential for absorbing this resonant voltage, which could degrade the overall power conversion efficiency. To overcome these drawbacks, the proposed converter employs a voltage clamping capacitor instead of the dissipative snubber. Therefore, the voltage stresses of all power semiconductors are not only clamped as the output voltage but the power conversion efficiency can also be considerably improved. Moreover, since the energy stored in the clamp capacitor is transferred to the output side together with the input energy, the proposed converter can achieve the higher voltage conversion ratio than the conventional tapped-inductor boost converter. Therefore, the proposed converter is expected to be well suited to various applications demanding the high efficiency and high voltage conversion ratio. To confirm the validity of the proposed circuit, the theoretical analysis and experimental results of the proposed converter are presented.

• 반도체디스플레이기술학회지
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• 제13권2호
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• pp.37-44
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• 2014

In this study, the performance of dye-sensitized solar cells with different thickness of the photelectrode film was simulated by using the electron-diffusion differential model. Through this simulation, the relationships between the thickness of the photoelectrode film and the performances (open-circuit voltage, short-circuit current density, and overall photoelectric-conversion efficiency) of cells were understood and the performances with different thickness of the photoelectrede film were also examined. For considering the refractive index in the liquid electrolyte and exploring the scattering effect of titanium dioxide particles with different sizes using the Mie light-scattering theory, the highest scattering effect of each particles was found out and the optimal size of the titanium dioxide particle was determined for light scattering in the photoelectrode film of dye-sensitized solar cell. Through experiment, the mixed titanium dioxide cell was better than the single titanium dioxide cell and generated a higher overall conversion efficiency because the optimal titanium dioxide particles in the phoelectrode film as light scattering.