• Journal of Advanced Marine Engineering and Technology
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• 제24권5호
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• pp.42-51
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• 2000

The performances of the simple expansion, perforated tube, and conical-connector type as an exhaust muffler are shown in this study. Applying a model in which the method of four-pole parameter is used makes theoretical estimation of the insertion loss. Experiment is performed for the measurement of the insertion loss under four cases according to the variation of the tail pipe length. By comparing the theoretical prediction with the experimental results, the validity of the modeling using the method of four-pole parameter is verified. The personal computer simulation programs for the above mentioned theory on the muffler design have been developed and exhaust sound level measurements have been carried out for simple expansion muffler, conical-connector muffler, perforated tube mufflers and the combined type of conical-connector and simple expansion muffler. The measured results for attenuation characteristics of noise for each muffler are compared with the computed theoretical results to verity the confidence and applicable limits of the theoretical equation derived.

• 대한기계학회논문집B
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• 제34권8호
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• pp.755-760
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• 2010

본 연구는 승용 디젤엔진의 입자상 물질 배출특성에 관한 것으로써, 엔진에서 배출된 입자상 물질이 배기관 및 후처리장치인 디젤산화촉매와 매연여과장치를 통과할 때의 특성 변화를 파악하기 위하여 후처리장치 각각 전 후단 및 배기관에서 직접 측정하였다. 또한 다양한 엔진회전속도 및 부하조건에서 측정함으로써 입자상 물질 배출 맵을 구축하였으며, 디젤산화촉매 및 매연여과장치의 입자상 물질 저감효과에 대해 평가하였다. 뿐만 아니라 배기재순환율과 연료분사시기를 변경시켜 입자상 물질의 배출특성 변화를 파악하였다. 모든 시험에서 입자상 물질을 5~1000nm 크기까지 측정할 수 있는 DMS500을 이용하였다.

• 한국군사과학기술학회지
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• 제21권2호
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• pp.195-203
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• 2018

Among the techniques of reducing the drag to increase the speed of underwater moving bodies, we studied on the drag reduction method by gas injection. Researches on gas injection method have been paid much attention to reduce the drag of vessels or pipe inner walls. In this study, we used a sintered metal mesh that can uniformly distribute fine bubbles by gas injection method, and applied it to a cylindrical underwater moving body. Using the KRISO medium-sized cavitation tunnel, we measured both the bubble size on the surface of the sintered mesh and the bubble distribution in the boundary layer. Then, drag reduction tests were performed on the cylinder type underwater moving models with cylindrical or round type tail shape. Experiments were carried out based on the presence or absence of tail jet injection. In the experiments, we changed the gas injection amount using the sintered mesh gas injector, and changed flow rate accordingly. As a result of the test, we observed increased bubbles around the body and confirmed the drag reduction as air injection flow rate increased.

• 한국화재소방학회논문지
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• 제26권4호
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• pp.70-76
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• 2012

본 논문에서는 디젤 승용차량에서 매연저감장치 손상에 기인한 차량화재에 대하여 기술하였다. 디젤 차량에서는 배출가스에 포함되는 입자상 물질을 저감하기 위하여 매연저감장치를 배기계통에 설치하고 있다. 매연저감장치는 입자상 물질의 과다 포집, 재상과정에서의 오류 및 흡기계통 불량 등에 의해 재생과정에서 파손에 이르게 되며, 매연저감장치가 파손되는 경우, 고온의 배출가스가 분출되고, 차량 하부 배기계통의 주변 가연물을 통해 화재로 진전된다. 매연저감장치 손상에 의해 화재가 발생되는 경우, 배기계통 배관 및 머플러 부분에 규산염계 무기화합물이 부착되는 특징을 나타내며, 이 규산염계 무기화합물은 매연저감장치 내부 필터 재료인 세라믹 부분이 손상되는 과정에서 발생된다. 따라서 화재가 발생된 디젤 차량의 경우, 머플러 주변에서 규산염계 무기화합물이 식별되는 경우, 매연저감장치 손상에 기인한 화재로 추정할 수 있다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.199.2-199.2
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• 2010

Biodiesels are well-known as alternative fuels. also we know that biodiesels increase NOx and reduce PM(Particulate Matter) by previous many studies. But PM in most these studies was considered about the mass. In this study, We have performed experimental test for PM and exhaust emission by mixed ratio of biodiesel in heavy duty diesel engine. PM was investigated by The nano particle number and the mass. The mass of PM was evaluated by using the standard gravimetric method, The number of PM was evaluated by using the EEPS(Engine Exhaust Particle Sizer), on the ESC(European Steady Cycle) mode. Sampled gas through dilutor was directly extracted from tail pipe and EEPS measured diluted exhaust gas. Biodiesel is made up of used cooking oil. Diesel as base fuel was sold on market and contains 2% biodiesel. The mass of PM was reduced 10% and the nano particle number was increased 5%. The particle number less than 40nm was increased, but the particle number more than 40nm is decreased.

• Journal of Advanced Marine Engineering and Technology
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• 제35권3호
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• pp.317-322
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• 2011

This work has investigated the exhaust emissions such as Total Hydrocarbon (THC), Nitrogen Oxides(NOx), and Particulate Matter (PM) characteristics emitted from the tail-pipe of a continuously variable valve timing (CVVT) gasoline-fueled engine with different intake valve opening timings and injection pressures at the part load condition. Valve overlap period was varied from $40^{\circ}CA$ to $10^{\circ}CA$ and fuel injection pressure was increased from 3.5 bar to 5.0 bar. THC and NOx emissions decreased as intake valve opening timing was advanced regardless of fuel injection pressure. When the fuel was injected with the condition of 5.0 bar at all of valve overlap ranges, THC levels were reduced by 55%. NOx concentrations were diminished about 75% as valve overlap increased. PM size distributions were analyzed as bi-modal type of the nucleation and accumulation mode. Comparing with fuel injection pressures, PM emission levels were decreased at high pressure injection of 5.0 bar condition.

• 대한기계학회논문집A
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• 제21권11호
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• pp.1837-1843
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• 1997

This study experimentally demonstrates the use of active muffler attached to the automotive exhaust system to reduce exhaust noise. For improving the signal to noise ratio in the process of estimation of secondary path transfer functions, the on-line algorithm that conventional inverse modeling is combined with adaptive line enhancer is used as the control algorithm. Active muffler is designed that the primary noise and the control sound are propagated as a plane wave in the outlet. Therefore, the error microphone could be placed out of the tail pipe center of a high temperature and the radiation noise to the outside could be reduced in the whole area around the outlet. The control experiment for reducing exhaust noise with active muffler is implemented during run-up at no load. From the experimental results presented, compared with the conventional off-line method, the proposed on-line method is capable to acquire a reduction of exhaust noise above 5 dB in overall sound power level.

• 한국자동차공학회논문집
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• 제8권6호
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• pp.87-100
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• 2000

HC and CO emissions during the cold start contribute the majority of the total emissions in the legislated driving cycles. Therefore, in order to minimize the cold-start emissions, the fast light-off techniques have been developed and presented in the literature. One of the most encouraging strategies for reducing start-up emissions is to place the light-off catalyst, in addition to the main under-body catalyst, near the engine exhaust manifold. This study numerically consider three-dimensional, unsteady compressible reacting flow in the light-off and under body catalyst to examine the impact of a light-off catalyst on thermal response of the under body catalyst and tail pipe emission. The effect of flow distribution on the temperature distribution and emission performance have also been examined. The present results show that flow distribution has a great influence on the temperature distribution in the monolith at the early stage of warm-up process and the ultimate conversion efficiency of light-off catalyst is severly deteriorated when the space velocity is above $100,000hr^{-1}$.

• 로봇학회논문지
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• 제8권4호
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• pp.247-255
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• 2013

This paper shows the development of a snake robot (KAEROT-snake V) which consists of 16 1-DOF actuator modules and head module. The modules are connected serially and the joint axis of each module is rotated by $90^{\circ}$ with respect to the previous joint so that the snake robot can move in the 3D space. A tail actuator module includes slip-ring and metal connector. KAEROT-snake IV developed in prior research could move in the 3D space and climb up in a narrow pipe. But its design was not appropriate to the unstructured tough environment and its speed was somewhat slow. A new actuator module is designed to enclose all parts of the module so that any wire is not exposed. The size and weight of the new module was slightly reduced. And the rotation speed and torque of the joint was increased by about twice when compared with pre-module. An embedded controller was developed so small that it can be mounted inside the module. The performance of the developed robot was demonstrated through various locomotion experiments.

• 한국소음진동공학회논문집
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• 제25권2호
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• pp.90-100
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• 2015

Recently, creating a signature sound for a brand has become more important in the automotive industry. It is important to remember that the people inside a vehicle are not the only one, who assess the signature sound, exhaust sound has become a more important factor. Most research has used psycho-acoustic parameter to objectively measure the aesthetic qualities of exhaust sound. However, these results do not parallel the results from subjective analysis. Therefore, this research focused on developing a method for objective quantification to assess the aesthetic qualities of exhaust sound in order to help develop a more appealing signature sound. To do so, the actual exhaust sound was synthesized and subjectively assessed at varied frequencies samples of 30 individuals employed at sejong R&D center. The results were analyzed using the science of harmony scale.