공회전시 배기계 이음에 대한 수학적 계산 및 예측기법에 대한 연구

장진만(Jinman Jang),김기동(Kidong Kim),김준완(Junewan Kim),김증희(Joonghee Kim) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11

In general, the main source of vehicle noise is the ignition of engine and to diminish the degree of the noise, exhaust system is used as complicated filters for attenuating the noise more or less. But, even these kinds of filters are playing their roles at their expected frequencies bands, some noises still can be detected by passengers. They are so called ‘abnormal noises’ ,which are discovered when their anti-filters are working well, and it is very difficult to find what is the real problem and what is the basis of this phenomenon. Usually, frequency analysis is the most useful method for studying noise phenomena, but main effect of abnormal noise comes from listener’s feeling, therefore only frequency analysis process is not enough to clarify not only the cause but also the phenomenon itself. In this study, one of the abnormal noise, which can be detected very easily at the tail pipe, has been examined by mathematical way to define the cause of feeling of abnormal noise more effectively and precisely, furthermore also noise filter development process has been developed as a result in order to design proper filter system for exhaust system. For the validation of this calculation and design process, virtual noise has been exerted to calculated filters which had been designed properly by the calculation of former step and then, the noise has been accessed as a listener’s feeling by sound feeling matrices of octave band modulation.

점성-대류 음향 방정식과 비 도플러 알고리즘을 이용한 배기계의 소음 성능 예측에 관한 연구

장진만(Jinman Jang),강영춘(Youngchun Kang),김기동(Kidong Kim),김준완(Junewan Kim),김영수(Youngsoo Kim),김중희(Joonghee Kim) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

Recently, the noise of vehicle is the one of the key factors for customers to purchase a vehicle and the most important part which is related to the noise is the exhaust system. Thus, car makers have their own ways to assess this exhaust noise not only to decrease the level of noise but to enhance the feeling of it. Typically, to do these things in the early stage of development, the tuning code of the exhaust system has to be made by CAE tool, which is very reliable but expensive, and the prototype parts of this code would be made for the validation test. Then this process can be iterated to meet the target of the performance. In this study, a new algorithm which adapts the ‘convective sound wave theory’ and ‘anti-Doppler effect’ has been introduced and with this algorithm, a calculation code for sound field estimation has been developed. And for the validation of the calculation code, various comparisons and validations were carried out with the result of wind tunnel test. Also the comparison with other CAE tool has been performed for the validity and the improvement of the new calculation code could be achieved.

3차원 대류 파동 방정식과 도플러 알고리즘을 이용한 배기계의 소음 성능 예측에 관한 연구

장진만(Jinman Jang),김준완(Junewan Kim),김중희(Joonghee Kim) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.10

Recently, the noise of vehicle is the one of the key factors for customers to purchase a vehicle and the most important part which is related to the noise is the exhaust system. Thus, car makers have their own ways to assess this exhaust noise not only to decrease the level of noise but to enhance the feeling of it. Typically, to do these things in the early stage of development, the tuning code of the exhaust system has to be made by CAE tool, which is very reliable but expensive, and the prototype parts of this code would be made for the validation test. Then this process can be iterated to meet the target of the performance. In this study, a new algorithm which adapts the ‘3 dimensional convective sound wave theory ‘and ‘Doppler effect’ has been developed. With this new algorithm, a brand new system for the calculation of tail pipe noise has been developed and validated by acoustic wind tunnel test. As a result of this study, various comparisons and have been carried out, for example, the comparison with other CAE tool has been performed for the validity and the improvement of the new calculation code could be achieved.

엔진 마운팅 및 배기 시스템의 동역학적 특성계발을 위한 시스템 벤치의 연구

장진만(Jinman Jang),강영춘(Youngchun Kang),김준완(Junewan Kim),김영수(Youngsoo Kim),김중희(Joonghee Kim) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5

It is very important to understand the dynamic characteristics of a vehicle like idle vibration, key on-off, and engine shake in the early stage of the projects before the prototype could not be prepared yet. Also, if there is no enough validation on the design of these performances, this can cause large changes in the engineering later on. Therefore, it is worthwhile to study a new method to validate the dynamic performances in early stage of engineering before advancing to the next stages. In this study, a system bench for the low frequency vibration simulation is introduced for the prediction and validation of power train and exhaust system dynamic performances. The system bench was built to have equivalent dynamic characteristics of the vehicle and power train system, and various comparisons and validations were carried out with CAE and vehicle test results so that validity and improvement points of the bench could be achieved.

아이들 진동 해석을 위한 CAE 모델에 관한 연구

강영춘(Youngchun Kang),장진만(Jinman Jang),김준완(Junewan Kim),김영수(Youngsoo Kim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11

Idle vibration, hot issue of the NVH problem has been studied for a long time. Engine excitation is the source of the idle vibration and Engine mount system, drive line and suspension system are main force transfer paths to the body. To predict the idle vibration performance in the beginning or prototype of a car developing program is very important process and therefore building the CAE model for idle vibration analysis became one of the most important works of car maker. The CAE model must have the force transfer systems that are mentioned before such as engine mounting system, drive line and exhaust system for the real situation. In this paper, CAE model for idle vibration analysis is validated by comparing test results from the bench made for the experiment testing a specific character of transfer systems in particular. Also, this CAE model is very useful in order to improve idle vibration performance in the level of chassis system.

C-대역 위성 통신용 20 W급 주파수 상향 변환기의 소형화

장병준(Byung-Jun Jang),문준호(Junho Moon),장진만(Jinman Jang) 한국전자파학회 2010 한국전자파학회논문지 Vol.21 No.4

본 논문에서는 C-대역 위성 통신용 20 W급 주파수 상향 변환기(BUC: Block Up Converter)를 소형화하기 위한 설계 방안을 제안하고, 이에 따른 제작 및 측정 결과를 제시하였다. 개발된 주파수 상향 변환기는 모뎀의 신호를 입력받아 적절한 주파수 필터링과 신호 세기 조절 및 전력 증폭 기능을 수행하며, 중간 주파수 회로, 국부 발진기 및 주파수 혼합기, 구동 증폭기, 전력 증폭기, 도파관 회로 및 전원 모듈의 6개 블럭으로 구성된다. 본 논문에서는 BUC를 소형화하기 위하여 개별 블럭을 각각 제작하여 케이블 등으로 연결하는 대신, 하나의 하우징 내에서 집적화하여 제작함으로써, 21×14×11 ㎤의 크기만을 가지도록 하였다. 특히 가장 큰 면적을 차지하는 도파관 필터 및 마이크로스트립-도파관 변환기를 하우징에 직접 제작하여 크기를 축소시켰다. 또한 Elliptic 필터를 포함한 다양한 마이크로스트립 필터를 설계하여 스퓨리어스 및 하모닉 규격을 만족시켰다. 제작된 주파수 상향 변환기는 43.7 ㏈m의 출력, 65 ㏈ 이상의 이득, ±1.84 ㏈의 이득 평탄도, -35.7 ㏈c의 IMD3, -105 ㏈c의 하모닉 값을 가지는 우수한 특성을 나타내었다. In this paper, a compact 20 W block-up-converter for C-band satellite communication is designed and implemented. The designed block up-converter consists of an intermediate frequency circuit, a mixer and local oscillator, a driver amplifier, a solid-state power amplifier, waveguide circuits, and a power supply module. To reduce the size of the block-up-converter, all circuits are assembled within an housing, so its dimension is just 21×14×11 ㎤. Especially, the waveguide filter and microstirp-to-waveguide transition are easily implemented using an housing. Also, to meet spurious and harmonics specification, various compact microstrip filters including an elliptic filter are integrated. Measurement results show that the developed block up-converter has good electrical performances: the output power of 43.7 ㏈m, the minimum gain of 65 ㏈, the gain flatness of ±1.84, the IMD3 of -35 ㏈c, and the harmonic level of -105 ㏈c.

아연합금 부품의 고장발생에 미치는 사용 환경의 영향

서금희(Kum-Hee Seo),이원식(Wonsik Lee),고세현(Se-Hyun Ko),장진만(Jinman Jang) 한국신뢰성학회 2006 한국신뢰성학회 학술대회논문집 Vol.2006 No.5