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고조파 전류 주입을 통한 견인전동기의 소음 진동 저감연구
정재덕(Jae-Deok Jung),정경태(KyungTae Jung),송경태(KyungTae Song) 한국자동차공학회 2023 한국자동차공학회 부문종합 학술대회 Vol.2023 No.5
As the electric vehicle market expands, the developing engineers have been putting lots of efforts into the electromagnetic noise reduction of the traction motors. The fundamental source of electromagnetic noise stems from the torque ripple and electromagnetic radial force reacting between rotor and stator of motors. Many approaches have been introducing a lot of methods to reduce the torque ripple, the research has studied the harmonic current injection method which is reducing torque ripple by adding a specific current value and phase into the input current. It was evaluated that the torque ripple is lowered from 3.43% to 0.68% under base rpm, and from 14.63% to 2.88% at high speed. And the radiated power level was also lowered at 2000 and 10,000 rpm by 2 dB and 1 dB respectively, and the radiated power in watt was reduced by 37% and 21% respectively. However, it is expected that it can be applied limitedly only below a certain speed because precise control is required.
정재덕(Jae-Deok Jung),고동신(Dong Shin Ko),허덕재(Deog Jae Hur),이원기(Won Gi Lee) 한국자동차공학회 2021 한국자동차공학회 부문종합 학술대회 Vol.2021 No.6
차량의 전동화로 인해 실내공간이 확장되고 이를 활용하기 위한 차량용 시트의 연구개발이 진행되고 있다. 기존 레일에 비해 3~4배 긴 레일을 설치하여 앞뒤의 이동 자유도를 높일 수 있다. 길어진 레일로 인해 강성이 낮아지고 구동 속도가 증가함에 따라 진동과 소음이 상대적으로 증가하게 된다. 진동 기여도 분석은 OTPA(Operational Transfer Path Analysis)를 사용하여 분석을 진행하였다. OTPA는 PCA와 SVD 과정을 거쳐 구동 중 여러 전달경로에 대한 기여도를 한 번에 도출한다. 또한 전통적인 방법과 달리 소음원 분리에 의한 경계 조건이 변하지 않는 장점을 갖는다. 센서 부착위치는 Photo.1과 같으며 S7위치의 가속도계를 대상(target)으로 설정하였으며 시트가 전진방향으로 구동할 때 각 부위의 기여도를 분석하였다. 시트 소음기여도 분석은 OTPA 분석 절차를 프로그램화 하여 데이터 처리를 수행하였다. S7의 앞뒤방향(x방향)에 대한 각 전달 경로 별 기여도 결과는 Photo.2와 같고 주파수에 따른 전체 진동레벨(overall)을 RMS로 나타내었다. S7의 앞뒤방향에 대한 기여도를 순위별로 나열하면 U2, W3, U1 순으로 나타나 어퍼레일과 스위블의 영향이 가장 지배적인 것으로 나타났다. 특히 어퍼레일의 경우 좌우방향(y방향) 진동에 의한 기여도가 가장 크게 나타났으며 스위블의 경우 위아래방향(z방향)의 기여도가 크게 나타남을 확인하였다.
[응용논문] OTPA 방법을 이용한 롱레일이 적용된 차량용 시트의 구동소음 기여도 분석 연구
정재덕(Jae-Deok Jung),고동신(Dong-Shin Ko),허덕재(Deog-Jae Hur),이원기(Won-Gi Lee) 한국자동차공학회 2021 한국 자동차공학회논문집 Vol.29 No.4
Indoor noise of a vehicle is becoming more important as indoor space increases due to the electrification of vehicles and autonomous driving. In order to utilize the wider indoor space, a vehicle seat with long-rail is required. A noise evaluation of the longer structure and increased operating speed is required. In this paper, OTPA was used to evaluate noise contribution. Responses were measured by accelerometers and microphone at points determined as noise points, and the contribution of each noise source was analyzed by using the SVD and PCA methods. In addition, sound pressure was measured directly at the headrest position and compared with the value calculated via response synthesis in order to increase the reliability of signal processing. The contribution of the structure-borne noise was greater than the motor noise, and the contribution of the lower rail was the highest. Furthermore, it was confirmed that the main frequency for noise contribution was 400 Hz.
인적서비스 품질이 호텔기업의 경영성과에 미치는 영향에 관한 연구
정재덕(Jae Duck Jung) 한국호텔관광학회 2001 호텔관광연구 Vol.3 No.1
A survey on the service quality of the 10 hotels was done find out position of hotel service level. Customers, travel agencies, and hotel employes of the hotels were involved in the survey and the survey result was analyzed by multidimensional scaling method(MDS) to identify service quality of the hotels. The result indicated that service quality is considered as an important service level was highly appreciated and very competitive but that of Renaissance and Plaza need to be improved for better hotel image. As shown in the survey result, Lotte and Shilla Hotels are not getting positive impression from the potential clients such as hotel employees and travel agencies. Considering this fact, such first class hotels need to put more effort in improving hotel image perceived by hotel employees and travel agencies.
정재덕(Jung, Jae-Deok),홍석윤(Hong, Suk-Yoon),길현권(Kil, Hyun-Gwon),송지훈(Song, Jee-Hun),권현웅(Kwon, Hyun-Wung),전재진(Jeon, Jae-Jin),서영수(Seo, Youngsoo) 한국소음진동공학회 2013 한국소음진동공학회 논문집 Vol.23 No.7
Underwater acoustic sensors are significantly damaged from underwater explosion. The damage that affects sensor should be evaluated for its smooth operations and safety. For satisfying these objectives, it is necessary to obtain more accurate values of the pressure and the energy flux density by distance. This paper is divided into two part. First, to obtain more accurate value of the pressure and the energy flux density at each point, the simulation results and the reference values were compared. For fitting to the reference pressure and the reference energy flux density, the sizes of fluid and TNT model are corrected, and the comparison results show good agreements. Second, based on these results, the structural integrity of underwater sensor structure was analyzed when TNT located in 10 meters from underwater sensors structure. This simulation used the commercial software MSC/DYTRAN.
OTPA방법을 이용한 철도차량 실내 소음 기여도 분석 연구
정재덕(Jae-Deok Jung),홍석윤(Suk-Yoon Hong),송지훈(Jee-Hun Song),권현웅(Hyun-Woung Kwon),노희민(Hee-Min Noh),김준곤(Jun-Kon Kim) 한국소음진동공학회 2016 한국소음진동공학회 논문집 Vol.26 No.1
The sensitivity of interior noise that the passengers perceive is comparatively high in the train, and structure-borne and air-borne types of noises come into the train. In this paper, to analyze contributions of these noise sources operational transfer path analysis(OTPA) is used. OTPA has some advantages of executing the contribution rates of several sources simultaneously, and in this work, 29 points are measured while running. Transfer functions between reference measurement points and response measurement points are calculated by the singular value decomposition(SVD) and Principal component analysis(PCA) method, and the frequency characteristics of the noise source are successfully derived. Also the interior noise is predicted and compared with measurement data to show the reliability.