• 한국소음진동공학회논문집
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• 제23권9호
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• pp.806-813
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• 2013

For the past years, higher power rating 2 stroke super long stroke diesel engines having more than 8 cylinders and larger cylinder bore are installed mainly on very large containerships to save on fuel consumption. However, these engines are prone to X-mode vibration due to 2nd node torsional vibration or the X-type moment, particularly because of the increase in total length and height. Recently, cases of excessive X-mode vibration often occurred on engine's major components. This vibration is manifested also as secondary vibration causing failure in engine-mount large structures. This study investigated the excitations caused by the 2nd node propulsion shafting torsional vibration that influence X-mode vibration of the main engine and practical countermeasures are proposed. An 8RT-flex82T 8 cylinder engine and 11S90ME-C 11 cylinder engine for a container ship was used as research model.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.411-416
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• 2005

Nowadays, diesel power plant using low speed two stroke diesel engine is widely used in islands and restricted areas. Considerations were given to its benefit of high thermal efficiency, reliability and durability compared to the other prime movers. However, various types of engine vibration affect neighboring buildings to their structural vibration. For this, diesel power plant are held liable for the troubles caused by these vibration. These are mainly due to the X- and H-type engine vibrations which we excited by the X- and H- guide force moment. Authors have identified a structural vibration of new pattern called ‘T-mode vibration’ due to the torsional vibration of shafting system. In this paper, T-mode vibration is analyzed through an experimental method based on the global vibration measurement.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.549-554
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• 2013

For the past years, higher power rating 2 stroke super long stroke diesel engines having more than 8 cylinders and larger cylinder bore are installed mainly on very large containerships to save on fuel consumption. However, these engines are prone to X-mode vibration due to $2^{nd}$ node torsional vibration or the X-type moment, particularly because of the increase in total length and height. Recently, cases of excessive X-mode vibration often occurred on engine's major components. This vibration is manifested also as secondary vibration causing failure in engine-mount large structures. This study investigated the excitations caused by the $2^{nd}$ node propulsion shafting torsional vibration that influence X-mode vibration of the main engine and practical countermeasures are proposed. An 8RT-82RT-flex 8 cylinder engine and 11S90S-ME 11 cylinder engine for a container ship was used as research model.

• 소음진동
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• 제6권6호
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• pp.701-708
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• 1996

Diesel power plants are frequently used as a power supplier on the island and the isolated places where electric power is required. The heat efficiency of the low speed 2 stroke diesel engines is higher than those of 4 stroke diesel engines or other heat engines and further its mobility and durability is also better than other engines. They can be also easily repaired and maintained. With these advantages, demand for the use of the low speed 2 stroke diesel engine as a power source is increasing. However, there are some disadvantages with these diesel engines such as the bigger vibrating excitation forces generated by higher combustion pressure in cylinder and by the inertia force of the reciprocating parts. Further, engine vibrations are transfered into their adjacent buildings and manufacturing factories and eventually produces local vibrations. In order to reduce X-mode vibration of engine body, several methods have been introduced in the recent researches. In this paper, accordingly, a new vibrationcontrol method applying a synchrophaser and a top bracing between two diesel engines is adopted in order to reduce these structural vibrations of diesel power plant. It was experimentally verified that the structural vibrations were greatly reduced by the phase adjustment for the 6th order X-mode vibration with the synchrophaser and the top bracing.

• 한국항공우주학회지
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• 제35권11호
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• pp.1028-1035
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• 2007

논문에서는 시험선인 소형 위그선의 주날개 구조를 엔진 및 프로펠러에 의해 유발되는 진동을 가진력으로 하여 강제진동 해석을 수행하였다. 대상 위그선은 2행정의 왕복엔진을 날개에 장착하여 프로펠러에 의한 추력으로 비행하며, 미는 형식(Pusher Type)의 엔진 배열을 취하고 있다. 유한요소해석을 위해서 구조해석 상용프로그램인 MSC/NASTRAN을 사용하였으며, 엔진의 주요 진동 특성인 H-mode 와 V-mode 그리고 X-mode를 특정 가진 주파수로 하여 주파수 응답 해석을 수행하였고, 엔진의 횡방향 진동 모드인 L-mode를 프로펠러의 회전에 의해 진동을 수반하는 가진 추력으로 가정하여 과도응답 해석을 수행한 후 날개의 진동 특성을 살펴보았다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제28회 춘계학술대회논문집
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• pp.217-221
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• 2007

본 연구에서는 대상체인 소형 위그선의 주날개 구조를 엔진 및 프로펠러의 기진에 의한 강제진동 해석을 수행하였다. 대상 위그선은 2행정의 왕복엔진을 날개의 좌 우에 각각 장착하여 프로펠러에 의한 추력으로 비행하며, 미는 형식(Pusher Type)의 엔진 배열을 취하고 있다. 엔진의 주요 진동 특성인 H-mode 와 X-mode 를 특정 가진 주파수로 하여 주파수 응답 해석을 수행하였고, 엔진의 횡방향 진동 모드인 L-mode를 프로펠러에 회전에 의해 진동을 수반하는 기진 추력으로 가정하여 과도응답 해석을 수행하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
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• pp.221-226
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• 1996

Structural vibrations of adjacent buildings, manufacturing factories and engines on the stationary diesel power plant were increased by the variation of phase angle between two engines sometimes. In this paper, top bracings and synchrophaser have been introduced in order to reduce these vibrations. As a result, all of structural vibrations were greatly improved by the phase adjustment of 6th order X-mode vibration with these.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제29회 추계학술대회논문집
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• pp.7-12
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• 2007

본 연구에서는 선행연구에 의해 설계되어진 20인승급 소형 위그선의 주날개 구조를 엔진 및 프로펠러에 의해 유발되는 진동을 가진력으로 하여 강제진동 해석을 수행하였다. 대상 위그선은 왕복엔 진을 날개에 장착하여 프로펠러에 의한 추력으로 비행하며， 미는 형식(Pusher Type)의 엔진 배열을 취하고 있다. 유한요소해석을 위해서 구조해석 상용프로그랩인 MSC/NASTRAN을 사용하였으며， 엔진의 주요 진동 특성인 X-mode 와 Y-mode 그리고 Z-mode를 특정 가진 주파수로 하여 주파수 응답 해석을 수행하였고, 엔진의 추력방향 진동 모드인 X-mode를 프로펠러의 회전에 의해 진동을 수반하는 가진 추력으로 가정하여 과도응답 해석을 수행한 후 날개의 진동 특성을 살펴보았다.

• Journal of Advanced Marine Engineering and Technology
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• 제26권6호
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• pp.631-637
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• 2002

Two stroke low speed diesel engines are used as a power supplier not only for marine vessel but also diesel power plant with a benefit of its higher mobility and durability than the other thermal engines. However, there are some disadvantages such as the bigger vibrating excitation forces generated by high combustion pressure in cylinders which various kinds of vibrations are caused. In this paper, it is theoretically studied to control engine body vibration using dynamic vibration absorber. As an actual case, dynamic absorbers are designed for controlling X-mode vibration of 9K80MC-S engine on the diesel power plant and its performance is identified by the vibration test both in shop and site

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.881-884
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• 2000

Recently mobile communication fields need piezoelectric ceramic resonators and filters as possible as small. The length-extensional vibration mode of a rectangular piezoelectric cesamic plate has the advantage of the small size, but the mode has not been studied sufficiently because it was not used extensively until now. In this paper, PZT + x[wt%l $Cr_20_3$ ceramics with rhombohedra1 phase were fabricated. And temperature stability for the mode of the ceramic specimen was investigated. Contrary to our expectations, addition of the stabilizer, $Cr_20_3$ did not promote the temperature stability for the mode in the PZT ceramic specimen with rhombohedra1 phase.