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디이젤 엔진에서 排氣管의 屈曲度가 排氣 騷音에 미치는 影響
문병수,김옥현,서정윤 대한기계학회 1986 대한기계학회논문집 Vol.10 No.3
본 연구에서는 실험적 방법을 통하여 엔진 배기관의 굴곡 형상이 배기 소음에 미치는 영향에 대해서 고찰하였다. 엔진으로는 4기통, 배기량 2164cc의 디이젤 엔진 을 사용하였으며 엔진의 보통 사용 범위인 1200∼3200rpm, 드로틀밸브의 개방도 25∼를 100% 구간에서 실험을 수행하였다. 굴곡부의 형상으로는 대부분의 배기관 굴곡이 원 호 형태임을 고헌하여 원호형의 굴곡관과 관의 꺽임부의 영향을 고찰하기 위한 직각형 굴곡관의 두가지 형태를 택하였따. 각 엔진의 운전 조건에서 굴곡관의 형상 치수를 바꾸어 가며 배기 소음의 음압(sound pressure level, SPL)과 스펙트럼을 얻었으며 이 들을 상호 비교 검토하여 배기관 굴곡 형상의 주요 설계 변수에 의한 배기 소음의 영 향을 고찰하였다. It is often occurred that exhaust pipe of an internal combustion engine should be bent due to some geometrical constraints. Especially for automobiles most of exhaust pipes of engines have curvature to avoid rear axles. In this paper effects of pipe curvature on the exhaust noise of a diesel engine have been studied experimentally. Experiments were carried out on a 4-cycle, 2164cc diesel engine. Two types of curvature, circular arc and retangle, were tested. Sound pressure level (SPL) and power spectrum of the exhaust noise were measured by inserting bent pipes of different curvature dimensions into the exhaust pipe at various engine operating conditions. The following results were obtained from this study. Among the engine operating conditions the exhaust noise was affected mainly by engine revolution speed. The noise was reduced by the circular arc bent pipe. The effectiveness of an arc bent pipe on the noise reduction was dominated by its arc angle and the maximum noise reduction was obtained by the angle of 180.deg.. But the noise reduction could not be obtained by the rectangular bent pipe, and at high engine speed the noise was rather increased due to turbulence of exhaust gas.
Traveling Wave solutions to the hyperelastic rod equation
문병수 한국전산응용수학회 2015 Journal of applied mathematics & informatics Vol.33 No.3
We consider the hyperelastic rod equation describing nonlinear dispersive waves in compressible hyperelastic rods. We investigate the existence of certain traveling wave solutions to this equation. We also determine whether two other equations(the $b$-family equation and the modified Camassa-Holm equation) have our solution type.
문병수,서정윤 대한기계학회 1986 대한기계학회논문집 Vol.10 No.5
An experimental study on the effects of exhaust pipe curvature on the performance of a diesel engine is presented. The experiments were carried out on a 4-cycle, 216 c.c diesel engine and two types of pipe curvature, circular arc and rectangle, were tested. The shaft output, shaft torque and specific fuel consumption were obtained by inserting bent pipes of different dimensions into the exhaust pipe at various engine operation conditions. It was found that the engine performance was decreased by the circular arc bent pipe and the effects were dominated by its arc angle. The decrease of engine performance was minimized by the arc angle of 180.deg.. By the rectangle pipes the performance was more decreased and the effects were little influenced by its dimensions. 본 논문은 참고문헌 (13)의 "디이젤 엔진에서 배기관의 굴곡도가 배기소음에 미치는 영향"에 대한 연구에 있어서 배기관의 굴곡성이 엔진성능에 미치는 영향에 대해서 실험적 방법을 통하여 구명하는데 있다. 따라서 4기통, 배기량 2,164cc의 디이젤 엔진을 사용하였으며, 굴곡의 형태는 원호형과 직각형의 두 경우에 대해서 실험하였다. 엔진의 운전조건은 일반적 사용 범위인 회전속도 1,200~3,200rpm드로 틀 밸브 개도25-100% 구간으로 잡고 곡관부의 형상치수를 변화시키며 부하, 흡기압력, 연료소비량, 배기온도 및 압력등을 측정하고 이것으로 부터 축출력, 축토오크, 연료소 비율을 계산하여 이를 상호비교 검토함으로써 곡관부의 형상치수가 엔진성능에 미치는 영향을 고찰하였다.영향을 고찰하였다.
MMC 기반 VSC-HVDC의 사고 위치에 따른 저항형 초전도 한류기와 암 인덕터의
문병수,최효상 대한전기학회 2024 전기학회논문지 Vol.73 No.2
High voltage direct current (HVDC) has gained prominence as a method for connecting renewable energy sources and interconnecting electric power systems between countries. Recently, the modular multilevel converter (MMC) has been developed and is undergoing construction worldwide. MMC-HVDC represents a new conversion technology that can address the issues of switching loss and harmonics. During a fault in the MMC-HVDC system, the fault current rises rapidly due to the discharging of the SM capacitor, making it difficult to interrupt with continuous AC side current feed. This phenomenon leads to the destruction of semiconductor devices. To resolve this issue, superconducting fault current limiters with fast response characteristics have been applied to the MMC. The SM capacitor discharge continues until all IGBTs are blocked. Generally, the IGBT block delay is about 3 ms. However, the response time of the Resistive SFCL (R-SFCL) is faster than 3 ms. In this study, the characteristics of R-SFCL and the arm inductor under multiple fault locations in a long cable of the MMC system are confirmed using PSCAD. The R-SFCL is modeled based on actual experimental data. As a result, as the inductor’s capacity increases, the peak current decreases, and the farther the fault location is, the faster the DC current reaches zero-point. Conversely, in the case of R-SFCL, as the resistance increases, the peak current decreases, and the closer the fault location is, the faster the DC current reaches zero-point.
超音波 硏削에 依한 화인 세라믹스의 加工性能에 關한 硏究
文秉秀,金聖淸,南丞炫 충북대학교 산업과학기술연구소 2002 산업과학기술연구 논문집 Vol.16 No.1
The fine ceramics are very difficult to grind to get high efficiency because they have not only high strength and brittleness but also high hardness. In this study, the ultrasonic grinding set-up that is operating by milling machine with attaching special device has been developed to get efficient machining of fine ceramics having wear resistance and brittle material. The following results through the experiment for various grinding conditions by the ultrasonic grinding are obtained. 1. Both the ultrasonic and the conventional grinding have 4 times better the grinding resistance value in horizontal direction than the vertical direction. 2. In case of table speed is low and grain size of diamond wheel is fine, the surface roughness is improved. But in case of grinding depth is increasing, the surface roughness is not improved because of increasing of grinding resistance and wornout of diamond wheel. 3. It could get high efficiency grinding effect by increasing grain size of diamond wheel. Also, it showed that tool wornout appears to be decreased than in case of conventional grinding under same condition.