• 소성∙가공
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• 제14권6호
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• pp.502-508
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• 2005

Hypereutectic Al-Si alloys have been regarded attractive for automotive and aerospace application, due to high specific strength, good wear resistance, high thermal stability, low thermal expansion coefficient and good creep resistance. Spray casting of hypereutectic Al-Si alloy has been reported to provide distinct advantages over ingot metallurgy (IM) or rapid solidification/powder metallurgy (RS/PM) process in terms of microstructure refinement. In this study, hypereutectic Al-25Si-2.0Cu-1.0Mg alloy was prepared by OSPREY spray casting process. The change of strain rate sensitivity and Creep transition were analyzed by using the load relaxation test and constant creep test. High temperature deformation behavior of the hypereutectic Al-Si alloy has been investigated by applying the internal variable theory proposed by Chang et al. Especially, the creep resistance of spray casted hypereutectic Al-Si alloy can be enhanced considerably by the accumulation of prestrain.

• 한국정밀공학회지
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• 제33권7호
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• pp.601-606
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• 2016

In this paper, an energy harvester is developed that has advantages regarding piezoelectric noise minimization, mass production, and an easily available environmental energy source, electromagnetic induction, as well as low-frequency bandwidth and high amplitude. A process for fabricating a three-dimensional multilayered planar coil using micro-electro-mechanical systems (MEMS) on a flexible printed circuit board FPCB is introduced. Optimal shape and size were calculated via internal resistance and inductance, and a prototype was fabricated through the MEMS procedure while considering the possibility of mass production. Although the internal resistance matched the designed value, the electromotive force generated did not reach the intended amount. The main reason for the decrease in efficiency was the low area of coil outskirt exposed to the magnetic field while there was relative motion between the magnet and the coil.

• 대한한의학방제학회지
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• 제23권1호
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• pp.141-150
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• 2015

Objectives : This study is to report the effects of Bangkibokryeong-tang(Fanjifuling-tang(BBT)) on stroke patient with Urinary tract infection.(UTI) Methods : A stroke patient diagnosed as UTI was treated with BBT (防己茯笭湯) at one-month intervals. We observed body temperature, amount of urine and recorded photographs of any changes during the treatment period. Treatment efficacy was assessed using urinary analysis. Results : After the treatment, there was improvement in urine analysis. And the symptoms of UTI and her conditions got better. Conclusion : The report suggests that BBT is effective in controlling various symptoms related to UTI with antibiotic resistance on stroke patient.

• 전기학회논문지P
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• 제59권1호
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• pp.112-116
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• 2010

Fuel cell as a renewable energy source is clean and has a lot of advantages. The source can solve energy crisis and environmental problems such as greenhouse effect, air pollution and the ozone layer destruction. This paper introduces hybrid system(hydro-Genius Professional, heliocentris) of solar cell and fuel cell. Also, this paper shows the I-P, V-I characteristics of fuel cells which are connected in parallel and series. From these results, we also found the maximum power was transferred at 0.5[${\Omega}$]. The terminal voltage was also decreased according to the current because of the internal resistance. The power transfer in series was two times than that in parallel.

• 전기학회논문지P
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• 제58권4호
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• pp.546-551
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• 2009

In this paper, we studied insulation characteristics of LED lamps for load and street lighting. LED lamps can be divided into internal type and external type according to converter type. In this study, we analyzed technology standard, K(Electrical Appliances Safety Standards) and KS(Korean Industrial Standards) about insulation resistance for LED lamps for load and street lighting, and measured insulation resistances for each measured point. Mostly, insulation resistances were measured high more than regulation value but some measured points were measured badly. We expect that the results of these experiments would be helpful for electrical safety of LED lighting installation, manufacture, construction and maintenance.

• 한국주조공학회지
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• 제26권2호
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• pp.92-97
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• 2006

Contact material is widely used as electrical parts. Ag-Cd alloy has a good wear resistance and stable contact resistance. But the disadvantages of Ag-Cd alloy are coarse Cd oxides and harmful metal, Cd. To solve the disadvantages of that, Ag-Sn alloy that has stable and fine Sn oxide at high temperature has been developed. In order to optimize Sn amount that affects the formation of the oxide layer on the surface, we worked for the microstructures and properties of Ag-Sn material fabricated by rapid solidification process. The experimental procedure were melting using high frequency induction, melt spinning, and internal oxidation. We have shown that the optimized Sn amount for high hardness is 7.09 wt%Sn. Surface oxide layer forms when Sn amount is over 9.45 wt%. The size of Sn oxide is 20 nm.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.292-292
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• 2010

Bimodal Tram is driven by both engine and Lithium Polymer battery pack which consists with 168 cells of LPB(80Ah, 650Vdc). LPB pack is very frequently charged and discharged in driving. Temperature inside of LPB pack makes an great effect on both charging and discharging capacity which seem to be related with LPB internal resistance. LPB internal resistance is increasing or little decreasing with the decreased temperature under 10 - $20^{\circ}C$ and the increased temperature over $30^{\circ}C$ which is similar to the temperature characteristics of single LPB cell. This paper has analyzed the driving characteristics of LPB pack for bimodal tram is running with either battery mode or hybrid mode.

• KSBB Journal
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• 제8권3호
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• pp.243-255
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• 1993

In this study, it was observed that hydrogen Productivity varied with stirrer speed, bead radius, input glucose concentration and dilution rate in a continuous stirred tank reactor in which immobilized R. rubrum KS-301 was used as a hydrogen-producing bacterium The mass transfer resistance due to cell immobilization was also studied. In order to estimate an effectiveness factor, Des of glucose was first obtained, which was subsequently represented by the correlation equation between Dos and Xb, As a result external mass transfer resistance could be neglected for stirrer speeds greater than 400rpn With bead radius increasing, the hydrogen productivity and internal effectiveness factor decreased. With input 91ucose concentration increasing, the hydrogen productivity and interval and external effectiveness factor increased. Although an Internal effectiveness factor was not affected, hydrogen productivity Increased with dilution rate increasing. An overall effectiveness factor remained nearly constant for the dilution rates investigate4 but increased with input 91ucose concentration increasing.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.532-533
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• 2014

본 논문은 LiPB의 SOH (State of Health)를 판별하는 방법중 배터리용량 (Ah) 및 저항 등가모델의 장 단점을 비교한다. 그리고 정확한 SOH 추정을 위해 DCIR (Direct Current Internal Resistance)을 사용한 판별 방법을 제안한다. 정확한 DCIR 값을 추정하기 위하여 EKF (Extended Kalman Filter)를 적용하고, MATLAB 시뮬레이션을 통해 DCIR 값을 확인한다. 또한, 실제 LiPB의 각 SOC (State of Charge) 상태마다 DCIR 값을 측정하고, 추정 값과 비교를 통해 정확도를 판단한다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.176-179
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• 2005

Spray casting of hypereutectic Al-Si based alloy has been reported to provide distinct advantages over ingot metallurgy (IM) or rapid solidification/powder metallurgy (RS/PM) process in terms of microstructure refinement. Hypereutectic Al-Si based alloys have been regarded attractive for automotive and aerospace application, due to high specific strength, good wear resistance, low coefficient of thermal expansion, high thermal stability, and good creep resistance. In this study, hypereutectic Al-25Si-2.0Cu-1.0Mg alloy was prepared by OSPREY spray casting process. High temperature deformation behavior of the hypereutectic Al-Si based alloy has been investigated by applying the internal variable theory proposed by Chang et al. The change of strain rate sensitivity and Creep transition were analyzed by using the load relaxation test and constant creep test.