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정적연소기에서 직접분사식 바이오 에탄올-가솔린 혼합연료의 연료온도에 따른 분무 및 연소 특성에 관한 실험적 연구
박기영 ( G Y Park ),김종민 ( J M Kim ),이성욱 ( S W Lee ) 한국액체미립화학회 2014 한국액체미립화학회 학술강연회 논문집 Vol.2014 No.-
As environment problem became a worldwide issue, countries are tightening regulations regarding greenhouse gas reduction and improvement of air pollution problems. With these circumstances, one of the renewable energies produced from biomass is getting attention. Bio-ethanol, which is applicable to SI engine, showed a positive effect on the PFI(Port Fuel Injection) type. However, Ethanol has a problem in homogeneous mixture formation because it has high latent heat of vaporization characteristic and in the GDI(Gasoline Direct Injection) type, mixture formation is required quickly after fuel injection. Particularly, South Korea is one of the countries with great temperature variation among seasons. With this reason, South Korea supply fuel additive for smooth engine operation during winter. Therefore, experimental study and investigation about application possibility of blending fuel is necessary. This paper demonstrates the spray and combustion characteristic by using the CVC direct injection and setting the bio-ethanol blending fuel temperature close to the temperature during each seasons: -7, 25, 35℃. The diameter and the width of the CVC are 86mm and 39mm. High-pressure fuel supply system was used for target injection pressure. High-speed camera was used for spray visualization and combustion visualization. Exhaust gas was measured by using the gas analyzer after combustion. Fig.1 represents the schematic diagram regarding the experimental apparatus. The experiment was conducted by setting the injection pressure and ambient pressure according to each temperature of bio-ethanol blending fuel as a parameter. The result of spray visualization experiment demonstrates that as the temperature of the fuel is lower, the atomization quality is lower, and this increase spray penetration and make mixture formation difficult. Injection strategy and combustion strategy according to fuel temperature and bio-ethanol blending rate is needed for improving characteristics.
대칭형 상지 운동기구를 이용한 손목 운동 시 뇌 활성도 패턴
태기식(K. S. Tae),김사엽(S. Y. Kim),송성재(S. J. Song),이소영(S. Y. Lee),박기영(G. Y. Park),손철호(C. H. Sohn),김영호(Y. H. Kim) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월
We developed a symmetrical upper limb motion trainer for chronic hemiparetic subjects. This trainer enabled the practice of a forearm pronation/supination and wrist flexion/extension. In this study, we have used functional magnetic resonance imaging(fMRI) with the developed symmetrical upper limb motion device, to compare brain activation patterns elicited by flexion/extension wrist movements of control and hemiparetic subject group. In control group, contralateral somatosensory cortex(SMC) and bilateral cerebellum were activated by dominant hand movement(Task 1), while bilateral movements by dominant hand(Task 2) activated the SMC in both cerebral hemispheres and ipsilateral cerebellum. However, in hemiparetic subject group, contralateral supplymentary motor area(SMA) was activated by unaffected hand movement(Task 1), while the activation of bilateral movements by unaffected hand(Task 2) showed only SMA in the undamaged hemisphere. This study, demonstrating the ability to accurately measure activation in both sensory and motor cortex, is currently being extended to patients in clinical applications such as the recovery of motor function after stroke.
Nd:YAG 레이저빔을 이용한 SCP 강판과 STS304강판 용접시 오프셋(off-set) 위치 결정에 관한 연구
윤부선(B. S. Yoon),김도훈(T. H. Kim),박기영(G. Y. Park),이경돈(G. D. Lee) 한국레이저가공학회 2004 한국레이저가공학회지 Vol.7 No.2
This work was attempted to join SCP sheet and STS304 sheet by using Nd:YAG laser beam. SCP sheet has good formability and low cost, while STS304 has excellent corrosion resistance and mechanical properties in high temp. In this experiment, butt joint type was used to develop the tailored blank welding for dissimilar steel. Sheets which have different thermal properties.<BR> Computer simulation was conducted to obtain the off-set position for efficient welding by considering laser power, scanning speed, focal length and basic properties. The result showed that the optimum thermal distribution was obtained when the laser beam was irradiated at 0.05 ~ 0.1 ㎜ off-set toward the SCP sheet side.<BR> The experiment was conducted based on the result of computer simulation to show the same optimum conditions. Optimum conditions were 3KW in laser beam power, 6m/min in scanning speed, -0.5㎜ in focal position, 0.1㎜ off-set toward SCP. Microhardness test, tensile test, bulge test, optical microscopy, EDS, and XRD were performed to observe the microstructure around fusion zone and to evaluate the mechanical properties of optimum conditions.<BR> The weld zone had high microhardness values by the formation of the martensitic structure. Tensile test measured the strength of welded region by vertical to strain direction and the elongation of welded region by parallel to strain direction.<BR> Bulge test showed 52% formability of the original materials. Bead shape, grain size, and martensitic structure were observed by the optical microscopy in the weld zone. Detailed results of EDS, XRD confirmed that the welded region was connected of martensitic structure.