• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1052-1053
• /
• 2008

도로 과적 차량은 일반 승용차보다 도로를 많이 훼손하여 도로, 교량의 사용 수명을 단축시키고, 유지보수 비용을 상승시키는 원인으로 분석되고 있다. 또한 과적 화물차량은 정상차량에 비해 도로 주행 흐름을 상대적으로 떨어뜨려, 도로 용량을 저하시키며, 소음과 진동의 발생, 배기가스 배출 등 여러 가지 문제를 발생시키는 원인이다. 특히, 도심지에서의 화물차 운행은 선진적인 단속체계가 더욱 필요하다. 현재의 단속시스템은 단속인력과 계측장비를 설치한 고정식의 과적 검문소를 운영하거나 이동식의 단속 검문을 병행하는 방식이다. 그러나 도심지의 경우, 교통정체, 고정식 검문소의 부지 확보 등 현실적으로 단속업무를 실시하기 어려운 환경이다. 본 논문에서는 현재 운영하는 고정식의 단속시스템을 자동 단속시스템으로 전환시키기 위한 기술적 구성 방안에 대해서 검토하였다.

• Journal of the Korean Society of Safety
• /
• v.12 no.4
• /
• pp.191-200
• /
• 1997

This paper discusses prediction of the sound pressure level produced by simple engine exhaust systems(plain pipe, plain expansion chamber pipe, plain expansion chamber with internally extended inlet and outlet pipe, perforated pipe enclosed in a plain expansion chamber) and a computer program has been developed which predicts the sound pressure level and the frequency spectrum. The program utilizes unsteady flow gas dynamic theory and acoustic theory to predict the pressure-time history in the exhaust system and the mass flow rate-time history at the open end of the system and the sound pressure levels(1/3 Octave band levels) and the frequency spectrum in semi-anechoic room. The predictions are compared with measured levels and show a high degree of correlation.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.7 s.94
• /
• pp.1833-1840
• /
• 1993

An efficient vibration analysis method, Component Mode Synthesis(CMS), for an exhaust system with bellows is presented. Analyses are performed for two types of bellows, where characteristics of vibration modes affecting idle shake and interior noise of a vehicle are examined. Also analyzed are the contributions of an exhaust and engine mounting system to the idle shake and interios noise. Comparison between the analysis and test is in good agreement, hence the CMS method is shown to be efficient and valid.

• Journal of Advanced Marine Engineering and Technology
• /
• v.22 no.5
• /
• pp.693-701
• /
• 1998

This study presents result of comparison between two other numerical method method of char-acteristics(MOC) and Lax-Wendroff method(LWM) applied at wave action analysis of intake and exhaust pipe in terms of calculated pressure velocity and emitted noise in the time and the fre-quency domain by means of fast Fourier transform analysis. Particularly FCT(Flux Corrected Transport)scheme is appended to LWM to protest unaceptable overshoots occurring near discon-tinuity. The final conclusion of this study is that MOC should be replaced by a second order finite difference approach because of larger contributions due to high frequency components than the results from the method of characteristics. Clear benefits we can get by change are faster calcula-tion higher accuracy conservation of mass and consistent calculation method.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.157-162
• /
• 2003

This study is analysis on the heat transfer of exhaust gas into the muffler at passenger Car. Numerical analysis with Computational fluid Dynamics(CFD) was carried out to investigate exhaust gas flow. The STAR-CD S/W used for the three dimensional steady state CFD analysis in a muffler. The Navier-Stokes Equation is solved with the SIMPLE method in a general cartesian coordinates system. Result of numerical simulation; Inlet and outlet temperature shown about ${\Delta}T=239K$, 216K, 202K at in the muffler. Heat transfer was progressed quickly by atmospheric temperature of muffler external at in the near wall.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.4 no.4
• /
• pp.179-189
• /
• 1996

An unstructured grid finite-volume method has been applied to predict the linear and nonlinear attenuation characteristics of the expansion chamber silencer system. In order to achieve a grid flexibility and a solution adaptation for geometrically silencer system. In order to achieve a grid flexibility and a solution adaptation for geometrically complex flow regions associated with the actual silencers, the unstructured mesh algorithm in context with the node-centered finite volume method has been employed. The present numerical model has been validated by comparison with the analytical solutions and the experimental data for the acoustic field of the concentric expansion chamber with and without pulsating flows, as well as the axisymmetric blast flowfield with open end. Effects of the chamber geometry on the nonlinear wave attenuation characteristics is discussed in detail.

• The Journal of the Acoustical Society of Korea
• /
• v.1 no.1
• /
• pp.82-91
• /
• 1982

To analyze the characteristics of engine exhaust mufflers by the acoustic theory is necessary for understanding the action of mufflers and for designing the mufflers. In many cases, the " Transmission Loss" is used in the analysis, but TL is not suitable for above purposes. In this paper the characteristics of the mufflers is analyzed by means of the four terminal constants of whole muffler system. After some approximation, the characteristics of engine exhaust mufflers is shown by the "D" in the four terminal constants. 20log│D│ can be easily constructed with the characteristics of each element of the muffler system. The analysis is done under the conditions of no loss and no gas-flow, so the result is approximate. But it is very useful for understanding the characteristics of the muffler system or each element of the system and for designing the muffler system.

• Proceedings of the KSR Conference
• /
• 1998.05a
• /
• pp.280-286
• /
• 1998

In recent years, the interest in noise increases gradually and the low noise level becomes one of the important performances in electrical equipment for railway vehicle. In the auxiliary power supply, most of the noise is made by the current ripple of alternating current reactor(ACL) which filters the output voltage. And this current ripple results from the voltage harmonics across the ACL. So the noise can be reduced by eliminating the voltage harmonics across the ACL. This paper shows harmonic eliminating technique which is making gating signals of upper and lower inverter have a phase difference in the 12-step inverter type auxiliary power supply. This technique was proved by testing on the developed 180KVA auxiliary power supply using IGBT.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.10a
• /
• pp.1065-1066
• /
• 2015

자동차의 수요가 폭발적으로 늘어났으며, 늘어난 자동차 대수를 고려하여 자동차 검사소 또한 많이 늘어났다. 그러나 최근에는 낮은 유지비용과 이동의 편의성으로 인하여 이륜자동차의 수요가 지속적으로 증가하고 있다. 이륜자동차의 경우 검사제도의 미비로 인하여 대기환경오염 및 불법개조로 인한 여러 가지 사회적 문제가 발생하고 있다. 이러한 이유로 최근에는 이륜자동차의 체계적 관리를 통하여 불법개조를 단속하고, 배기가스 오염물질에 의한 대기오염 및 이륜자동차 소음관리를 위하여 이륜자동차에 대한 검사 제도가 더욱 강화되고 있다. 본 논문에서는 중고차 성능점검 시스템 및 기능종합진단 시스템의 아키텍처를 통하여 이륜자동차에 적용되는 종합관리시스템 적용될 수 있는 통신 프로토콜을 분석하고 개발에 필요한 중요한 설계요소를 제시하고자 한다.

• Journal of Convergence for Information Technology
• /
• v.9 no.5
• /
• pp.158-164
• /
• 2019

Recently many studies to reduce the noise of dental hand piece which generate inevitably mechanical sound to offend to the ear of a patient have been spotlighted. Generally, methods of adding a sound absorbing material inside the exhaust valve, air pump of machine or automobile are widely reported as optimal way to reduce the mechanical noise. In this paper we studied a new UV laser aided manufacturing of micro-porous structure of EPP substrate and applied dental hand piece to improve the efficiency of sound absorption. A lot of micro-sized pores were fabricated with UV laser processing on the surface of sliced EPP substrate. From fundamental experiments, more high-performance of micro-porous EPP substrate has finally demonstrated for sound-absorbing structure of the micro muffler inside dental hand piece, which actually has the excellent potential to apply a lot of potable machine.