• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.477-478
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• 2009

• 수산해양교육연구
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• 제9권2호
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• pp.179-187
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• 1997

경상대학교 해양과학대학 실습선 경양호 기관의 회전수와 추진기의 핏치각을 전속(全速)(R.P.M. 680, P.A. $18^{\circ}$), 반속(半速)(R.P.M. 640, P.A. $16^{\circ}$), 미속(微速)(R.P.M. 580, P.A. $10^{\circ}$)의 상태로 하고, 이들 각각에 따른 시험선의 트림을 2.45m, 2.15m, 1.45m 선미 트림으로 조정하여 마일 포스트를 왕복하여 도플러 로그의 대지 속력과 실속력을 측정하여 비교 분석한 결과 도플러 로그 지시속력은 트림의 변화에 큰 영향을 받았으나 속력에는 그다지 큰 영향을 미치지 않음을 알 수 있었다. 한편 세 경우 모두 선의 트림이 2.15m 선미 트림 일때 속력 변화의 폭과 오차가 가장 적어 선체가 안정되고, 트림의 순간적 변화가 적으므로 최적의 상태라 할 수 있다. 그리고 미속 전진중 일때 속력 변화의 폭이 가장 크게 나타났는데 이것은 마일 포스트 사이를 통과 하는데 소요되는 시간이 전속, 반속 전진중 일때 보다 많이 소요되므로 그 간에 외력의 영향을 많이 받았기 때문이라 추정되었다. 특히 세 경우 모두 처음 마일 포스트를 통과한 후 약 30초 사이에는 도플러 로그의 지시속력이 저속임과 동시 속력 변화의 폭이 아주 크게 되었다가 그 후는 완만한 속력 변화를 보였는데 이러한 원인은 기관의 회전수와 핏치각을 변화시킨 후 최적의 상태가 되기 이전에 마일 포스트를 통과한 때문이라 생각된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권5호
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• pp.492-506
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• 2009

Index structures that are based on sequence matching for XPath processing such as ViST, PRIX and LCS-TRIM have recently been proposed to reduce the search time of XML documents. However, ViST can cause a lot of unnecessary computation and I/O when processing structural joint queries because its numbering scheme is not optimized. PRIX and LCS-TRIM require much processing time for matching XML data trees and queries. In this paper, we propose a novel index structure that solves the problems of ViST and improves the performance of PRIX and LCS-TRIM. Our index structure provides the minimum sequence matching scheme to efficiently process structural queries. Finally, to verify the superiority of the proposed index structure with the minimum sequence matching scheme, we compare our index structure with ViST, PRIX and LCS-TRIM in terms of query processing of a single path or of a branching path including wild-cards ('*' and '//' ).

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.464-473
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• 2006

This paper summarises theoretical and experimental work on the feedback control of sound radiation from honeycomb panels using piezoceramic actuators. It is motivated by the problem of sound transmission in aircraft, specifically the active control of trim panels. Trim panels are generally honeycomb structures designed to meet the design requirement of low weight and high stiffness. They are resiliently-mounted to the fuselage for the passive reduction of noise transmission. Local coupling of the closely-spaced sensor and actuator was observed experimentally and modelled using a single degree of freedom system. The effect of the local coupling was to roll-off the response between the actuator and sensor at high frequencies, so that a feedback control system can have high gain margins. Unfortunately, only relatively poor global performance is then achieved because of localisation of reduction around the actuator. This localisation prompts the investigation of a multichannel active control system. Globalised reduction was predicted using a model of 12 channel direct velocity feedback control. The multichannel system, however, does not appear to yield a significant improvement in the performance because of decreased gain margin.

• 한국정보통신학회논문지
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• 제15권12호
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• pp.2582-2589
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• 2011

본 논문에서는 차량 OBD-II 인터페이스를 통해 쉽게 확보할 수 있는 차량 진단 정보로부터 차량의 연료 소모량을 예측하는 방법을 제안하였다. 이를 위해 차량으로부터 제공되는 흡입 공기량(MAF), 단기 연료 보정(STFT), 장기 연료 보정 (LTFT) 값이 연료 소모량과 관계가 있다고 가정하고, 흡입 공기량, 단기 연료 보정, 장기 연료 보정을 입력 변수로 하며, 연료 소모량을 출력으로 구성하였다. 차량 OBD-II 인터페이스를 이용하여 획득한 값과 차량관련 전문업체로부터 지원받은 연료 소모량 값의 관계를 연소 반응식으로 구성하였다. 제안한 방식의 유용성을 확인하기 위해 도심 도로 5 Km를 실제 주행테스트를 수행하였고, 제안한 차량 데이터를 이용한 연료 소모량 예측 알고리즘의 성능을 확인하였다.

• 한국음향학회지
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• 제37권4호
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• pp.233-241
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• 2018

본 논문에서는 기존에 없었던 도어트림 그립핸들에서 반복된 하중으로 인해 발생하는 소음을 사전에 검증할 수 있는 내구 시험법을 개발하고자 하였다. 시험 방법은 그립 핸들이 받는 하중 모드, 내구 횟수를 고려하여 개발하였으며, 시험 방법의 유효성을 확인하기 위해, 양산 초기 제품에 시험 법을 적용하여 필드클레임에서 발생한 도어트림 그립 핸들 소음을 재현하였다. 최종적으로, 현재 개발된 시험법을 통해서 후속 개발 제품의 소음 검출 및 개선하는 데 활용하고 있다.

• 대한조선학회논문집
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• 제51권5호
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• pp.349-355
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• 2014

The resistance test of a high speed craft such as planing ship is performed with a high speed towing carriage instead of ordinary towing carriage because of the speed limitation. In the resistance test using high speed towing carriage, the model ship is fixed to the carriage to restrain the running attitude for enough measuring time. Such method is called fixed model test method. In the fixed model test method, to get the appropriate running attitude, the model test is iteratively repeated until the trim moment and lift force are close to zero. In this research, trim free model test method is investigated to reduce the number of iteration. And, the limitation of towing speed range in the trim free model test method is investigated.

• 대한조선학회논문집
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• 제57권4호
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• pp.230-240
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• 2020

The aim of this study was to investigate the manoeuvrability of a ship in different Center of Gravity (CG) conditions. Free Running Model Tests (FRMT), such as 35°turning circle tests, 20/20 zigzag manoeuvring tests, and 10/10 zigzag manoeuvring tests, were conducted in three GM and three trim conditions with 1/65.83 scaled KRISO Container Ship (KCS). The test results indicated that KCS in the lower GM condition and the trim by bow condition showed reduced advance and tactical diameter in turning circle tests and increased overshoot angles in zigzag tests, and those manoeuvring indices were strongly related with roll angle. In addition, sensitivity indices for three-axis CG position were suggested with prior research, and it showed that y-axis CG position significantly affected manoeuvrability of KCS due to the low GM. Therefore, in the case of KCS, it is evident that the roll angle during manoeuvre is closely related with manoeuvring indices.

• 대한조선학회논문집
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• 제46권4호
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• pp.391-397
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• 2009

In this paper, longitudinal static stability is investigated, which is an essential requirement for the safety and the performance of the human powered hydrofoil boat (HPHB). In case a disturbance changes the trim angle of the boat, the derivative of the moment about the center of gravity must be negative in order to make the boat to be stable. The equation to evaluate the longitudinal static stability of the EPISODE, a HPHB of Chungnam National University with a height controlling system(HCS) is derived. From the derivative it is confirmed that a longitudinal and vertical position of the center of gravity is important for a HPHB. The range of a trim angle while the boat is foil-born was found with a HCS under the condition of mechanical restraint. And it is confirmed that the longitudinal static stability is satisfied for EPISODE in certain range of a trim angle. It is also shown that the longitudinal static stability and a range of the trim angle can be determined from the principal dimensions of a HPHB, therefore, it can be applied from the stage of the conceptual design of HPHB.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.691-698
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• 2020

In this study, the effects of hydrodynamic interceptors on a high-speed vessel were investigated to identify the operating principle based on experiments. Model tests were performed using a high-speed towing carriage. The resistance, trim and rise of Center of Gravity (CG) of the high-speed vessel were measured for various ship speeds and interceptor heights. As the interceptor height increased, the trim and rise of CG were reduced. In order to quantitatively analyze these phenomena, the pressure at the stern bottom was measured using tactile sensors. The reliability of the measured results from the tactile sensors was verified through repeat tests. The pressure on the stern bottom increased in proportion to the interceptor height, as the interceptor partially blocked the flow there. Then, the trim was reduced. However, as the ship speed increases, the pressure at the location close to the interceptor decreases when the interceptor height is small, leading to increased trim. Therefore, the interceptor height for running attitude control should be carefully determined considering multiple factors in the operating condition of the high-speed planing hull.