• 한국철도학회논문집
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• 제8권6호
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• pp.513-519
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• 2005

The Korean Tilting Train eXpress may produced a strong micro-pressure wave in tunnel exit because of large train/tunnel area ration of conventional railways. This micro-pressure wave causes an impulsive noise which is a serious environmental noise pollution near tunnel exit. Tunnel hood can be the method of reducing the micro-pressure wave in tunnel exit. Therefore, parametric studies for tunnel hood are performed with respect to the hood length and size to investigate the effects of the tunnel hood. Also, axi-symmetric unsteady compressible flow solver was used to analyze train-tunnel relative motion. According to the result of numerical analysis, the maximum micro-pressure wave in tunnel exit is reduced by 56% throughout the hood establishment on conventional railways.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.355-358
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• 2005

This study aims at comparing the noise characteristics of conventional and functional hood. Measurement and analysis was carried out in anechoic room and actual environment. In case of anechoic room, intensity and sound pressure level were measured. In case of actual environment sound pressure level under different apartment size and distances. Sound pressure level of actual environment was higher than that of anechoic room. It is concluded that noise characteristics were different from each other in case of anechoic room and actual environment.

• 한국생산제조학회지
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• 제22권2호
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• pp.304-309
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• 2013

In chemical, medical or biology laboratories Fume Hoods are basic facilities which can protect researchers from dangerous gas as blowing the contaminated air outside. After the air inside the laboratory room is sucked into the hume hood, then, it is blew out by a fan rotated by an AC induction motor. In addition, a damper controls the inside opening of a duct, which the air flows through. The face velocity, air velocity through the front door, have to be kept constant as the set value even though the opening of the door is varied. However, conventional fume hood used to be operated by operator's manual switches. So that, in this paper an automatic control system is developed which controls the face velocity by adjusting the rotating speed of the blow motor and the opening of the damper. Experiments show that this developed system can be used at such laboratories.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.154-158
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• 2009

The vortex ventilation system (VV) which uses a rotating finned swirler installed coaxially with the exhaust duct is a very effective local ventilator. VV can enhance the capture depth by a factor of 3-5 compared to the conventional exhaust hood, in the absence of any solid walls nearby. In real situations there may exist ceiling, side wall and floor, all of which can affect the flow field and suction performance by way of the no-slip condition on the walls. 3D CFD simulation was performed in order to see the effect of the floor on the capture performance of the VV. The presence of floor reduced suction flow velocity, and increased the critical rotational speed which is the rotational speed required for stable vortex formation. Flow velocity profile along the axis could be well approximated by a universal functional form when the distance from the exhaust inlet is non-dimensionalized by the distance to the floor. Capture depth, define by the distance from the exhaust inlet to a point of velocity decreased to 10% of that at the inlet, is reduced by about 10% when the floor distance is 6 times the exhaust hood diameter.

• 한국자동차공학회논문집
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• 제19권6호
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• pp.61-67
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• 2011

The cooling module needs enough space (or distance) from hood to absorb the energy from any pedestrian collision. Downsized cooling module for pedestrian protection is important to reduce the severity of pedestrian injury. When a vehicle collision happens, the downsized cooling module is required to reduce the risk of injury to the upper legs of adults and the heads of children. In this study, the performance of cooling module to cool the engine was investigated under 25% height reduction. The heat dissipation and pressure drop characteristics have been experimentally studied with the variation of coolant flow rate, air inlet velocity and A/C operation ON/OFF for the downsized cooling module. The results indicated that the cooling performance was about 94% level compared to that of the conventional cooling module. Therefore, we checked that the cooling module had good performance, and expected that the cooling module could meet the same cooling performance as conventional cooling module through optimization of components efficiency.

• 한국표면공학회지
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• 제27권4호
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• pp.207-214
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• 1994

In consideration of global environmental protection and fuel saving, aluminum alloy sheets for auto body panels such as hood, fender etc., are expected one of the most promising materials for weight saving of cars. The chemical conversion coating is required to prevent the filiform corrosion occurring on painted aluminum. However the conventional process for the composited material mixed with aluminum and steel is complexs; aluminum part is chromated and assembled to the body, and then the steel body undergoes Zn phosphating. In order to overcome the low productivity due to the complex process and the environmental problem with a conventional process, a simultaneous zinc phosphating process for alsuminum and steel in an assembled condition is demanded. Newly developed phosphate solution has been investigated to characterize the phosphating behavior under various conditions. The optimum conditions of the phosphating solution for the application of the paint treatment derived as follows : about 0.3 for the ratio of Zn to $PO_4$, , 200~500 ppm for the concentration of fluoride ion, and 2.5~4.0 for pH. The concentration of dissolved aluminum ion must be kept below 2--ppm and suitable accelerator is found to be a mixture of 1g/$\ell$ $NO_2\;^-$, and 6g/$\ell$ $NO_3\;^-$.

• 한국자동차공학회논문집
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• 제20권6호
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• pp.67-72
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• 2012

Novel Front End Module(FEM) with improved pedestrian protection is very important to reduce the severity of pedestrian injury. The FEM needs to have enough space from hood to absorb the energy from any pedestrian collision. In this study, the cooling performance of the FEM to cool the engine was investigated under 25% height reduction. The results indicated that the cooling performance analysis was about 86% level compared to that of the conventional FEM. Also, good qualitative agreement between CFD predictions and experimental measurements was found. This FEM needs the cooling performance enhancement for changed air flow path at the frontal part of vehicle. Therefore, we showed an improved performance using air guide setup and shape modification under the high load condition.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1312-1316
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• 2007

Strip casted and rolled magnesium sheet is become exiting material for car manufacturer, due to its better formability and specific strength compare with conventional extruded sheet. TWB technology was attractive for car body designer, because it saves the weight of the car without strength loss. In this study, the laser welding performance of magnesium sheet was investigated for Mg TWB panel manufacturing. The material was strip casted and rolled magnesium alloy sheet contains 3 wt% Al and 1 wt% Zn (AZ31). Lamp pumped Nd:YAG laser of 2kW was used and its laser light was delivered by optical fiber of 0.6mm core diameter to material surface with focusing optics of 200mm focal length for TWB welding. The microstructure of weld bead was investigated to check internal defects such as inclusion, porosity and cracks. Also mechanical properties and formability were evaluated for press forming of car body. For the results, there was no crack but inclusion or porosity on weld at some conditions.The tensile strength of weld was over 95% of base metal. Inner and outer panel of engine hood were press formed and assembled at elevated temperature.

• 한국초지조사료학회지
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• 제28권3호
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• pp.193-202
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• 2008

국내 보리 소비가 급격히 감소하면서 재배 면적도 줄어들어 겨울철 논을 이용한 보리 재배 농가의 대체 소득원이 보리를 활용한 조사료 생산이다. 경지이용률 제고와 양질의 조사료 공급은 국내 축산 농가의 국제경쟁력을 올릴 수 있어 최근 청보리의 생산은 현저히 증가하고 있는 추세이다. 총체사료용 청보리는 식용보리에 비하여 전체적인 건물수량성이 높아야 하고 가축이 먹기에 좋도록 형태적으로도 개선되어야 한다. 그 동안 개발된 총체사료용 청보리는 벼와의 작부체계에 알맞도록 조숙이면서 건물수량이 ha당 10$\sim$12톤 (생체수량 평균 33톤/ha)을 보이는 영양, 선우, 상원, 소만 등을 개발하였으며, 가축의 기호성이 좋도록 거친 까락을 매끈망으로 개선한 우호, 까락이 퇴화한 삼차망 보리 유연과 줄기에 잎귀를 없애서 부드럽게 만든 다미 등 초형을 개선하였다. 이러한 사료 전용 청보리 품종들은 사료가치도 우수한 것으로 평가되어 육종적으로 개선한 각 품종들의 고유 생육특성을 중심으로 보고하는 바이다.

• 한국산업보건학회지
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• 제15권3호
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• pp.166-175
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• 2005

Health effects associated with metal working fluid (MWF) exposures include dermatitis, respiratory disease, hypersensitive pneumonitis, and asthma. Frequently, occupational exposures to MWFs are controlled by ventilating an enclosure with an air cleaning unit that includes a fan preceded by various kinds of filtration. There are several kinds of air cleaning units used in machining centers. But the associated troubles have hindered from efficiently using these devices. The main problem is the relatively short period of filter replacement. The reason is that the air cleaning units usually do not have the de-oiling systems, thus leading the earlier clogging of filters and reducing the flow rate of hood. Thus, the first stage of study was conducted to overcome this problem by developing the new oil mist collector equipped with the easy de-oiling system. The principle of de-oiling is that the centrifugal force generated by spinning the drum covered by filter fabric separates oils from the filter fabric. It would be very similar to the spin-dry laundry. By adopting this de-oiling technique, the problems associated with the conventional oil mist collectors could be solved. Several tests/analyses were performed to make the lab-scale oil mist collector. The collection efficiencies and the de-oiling efficiencies of commercially available filter fabrics were tested. Subsequently, the endurance test were conducted by observing SEM photos of filter fabrics and measuring tensile strength/expansion coefficient after spinning the filter drum for 20 minutes at the different rotation speeds. By doing these experiments, the most appropriate filter fabric and rotation speed/duration were selected. Finally, the new oil mist collector was designed. In the near future, this device must be tested in the real machining center.