• Advances in aircraft and spacecraft science
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• 제9권1호
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• pp.39-57
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• 2022

Instead of developing new guided missiles, converting unguided missile into guided ones by adding guidance and controlkits hasbecome aglobaltrend.Ofthemost efficient andwidelyused thrust vector control(TVC) techniquesin rocketry isthe jet vanes placed inside the nozzle divergentsection. Upon deflecting them, lift created on the vanesistransferred to the rocket generating the desired control moment. The presentstudy examinesthe concept of using an add-on jet vaneTVC kit to a plain nozzle.The impact of adding the kit with different vaneslocations and deflectionanglesisnumericallyinvestigatedbysimulatingtheflowthroughthenozzlewiththekit.Twohingelocations are examined namely, at 24% and 36% of nozzle exit diameter. For each location, angles of deflection namely 0°, 5°, 10°, and 15° are examined. Focus is made on variation of control force, thrust losses, lift and drag on vanes, jet inclination, and jetflow structure withTVCkit design parameters.

• 한국가시화정보학회지
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• 제21권3호
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• pp.57-64
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• 2023

An open pulsating heat pipe operates continuously by inflow and outflow fluids through an open-type condenser. The open pulsating heat pipe is a device capable of obtaining the thrust due to the variation of internal pressure during phase change. Therefore, the open pulsating heat pipe is a suitable device to move fluids if the heat source such as waste heat exists. Many numerical studies have not been sufficiently conducted on the open pulsating heat pipe. In this study, the numerical analysis of the open pulsating heat pipe is performed according to the length of the condenser section. The OpenFOAM software is used to obtain the thrust and the flow visualization for the open pulsating heat pipe.

• 수산해양기술연구
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• 제23권1호
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• pp.30-38
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• 1987

좁은 틈새를 가진 원판밸브의 추력에 대한 이론적 해석 및 실험 결과로부터 다음과 같이 요약할 수 있다. 1. 원판 밸브의 틈새가 비교적 작은 경우(H/D sub(1)가 0.1 이하) 즉, 유량이 적을 때에는 점성류가 지배적이고 이론식으로부터 추력을 높게 예측할 수 있었다. 2. 압력의 영향에 대한 추력은 입구 압력이 낮을수록 이론결과와 실험결과가 잘 일치하고 높을수록 관성의 영향이 크게 나타나는 경향을 보였다. 3. 밸브 크기 변화에 대한 추력의 영향은 D sub(2)/D sub(1)=>4.6에서는 포물선적으로 감소하고 그 이하에서는 직선적으로 감소하였다.

• 한국추진공학회지
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• 제11권6호
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• pp.35-41
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• 2007

부하율은 모터구동 밸브에서 밸브 스템에 가해지는 부하(load) 변화에 따라 구동기 torque와 스템 thrust 사이의 상관관계가 변하는 현상이다. 본 논문에서는 게이트밸브의 열림행정에서 발생되는 부하율 특성을 분석하고 밸브 성능평가시 적용하는 부하율의 타당성에 대해 기술하였다. 또한, 총 40대의 게이트밸브에 대해 정적시험 및 동적시험을 수행하고 본 연구에서 개발한 열림행정에서의 부하율 평가 방법론을 적용하여 각 밸브의 열림행정 부하율을 평가한 결과를 수록하였다. 연구결과로서 열림행정의 부하율은 차압이 150 psi보다 높은 경우 (-)값으로 나타났으며, 이러한 현상은 유체 차압이 높을수록 크게 나타나는 결론을 얻었다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.213-217
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• 2011

고체 로켓 모터의 추력 제어를 위한 핀틀 노즐에 대한 비정상 수치해석을 수행하였다. 비정상 수치해석 기법을 이용하여 핀틀의 위치 변화를 고려하였으며, 다양한 핀틀 형상의 동적 특성에 대한 연구를 수행하였다. 시간에 따른 핀틀의 위치 변화를 고려하기 위해 이동격자기법을 적용하였다. 다양한 형상의 핀틀에 대하여 핀틀의 이동에 따른 노즐 목의 위치 및 크기를 예측하였고, 수치해석 결과와 비교하였다. 그리고 엔진성능의 동특성을 관찰하기 위하여 비정상 수치해석을 통해 연소실 압력, 추력 등을 분석하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.376-381
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• 2009

The increasing needs for higher cargo capacity in the container vessels' fleet has led to ship builder's demand for higher power output rating engine to meet the propulsion requirement, thus, leading to the development of super large two stroke low speed diesel engines. This large sized bore engines with more than 12 cylinders are capable of delivering power output up to more than 100,000 bhp at maximum continuous rating. The thrust variation force due to axial vibration occurring in propulsion shafting of these ships are transmitted to ship structure via thrust bearing. This force may vibrate the super structure of ship in the fore-aft direction and the fatigue strength of crank shaft can be decreased by additional bending stress increase in crank shaft pin and journal. In this paper, the axial vibration of propulsion shafting system on the 14RT-flex96C super large diesel engine with 14 cylinders is identified by theoretical analysis and vibration measurement.

• 대한기계학회논문집A
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• 제24권5호
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• pp.1305-1313
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• 2000

In a co-rotating scroll compressor, both scrolls rotate on their fixed axes contrary to the conventional orbiting type scroll machine. This implies fixed locations and directions of the gas pressure force and sealing force. Because the tilting moment is mainly caused by interplay between the resultant force of above forces and bearing reaction force, the variation during one cycle is relatively small. Under real operation, this moment is balanced by the restoring moment created by the reaction between the baseplate and thrust bearing or between the scroll tip and baseplate. If these reactions become too large, greater torque is required due to increased friction in addition to the wear of mating parts. Consequently, appropriate study and minimization of tilting moment is important in the design of scroll machines. In this study, taking into account of the small variation of tilting moment during one cycle, we minimize the moment and thrust bearing reaction force by a properly designed back pressure chamber. As a result, for both the driving and driven scrolls, the tilting moment and the reaction force of thrust bearing can be minimized. And the stability is improved for all cases.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.24-34
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• 2021

This paper predicts the speed-power-rpm relationship in regular head waves using various indirect methods: load variation, direct powering, resistance and thrust identity, torque and revolution, thrust and revolution, and Taylor expansion methods. The subject ship is KVLCC2. The wave conditions are the regular head waves of λ/LPP = 0.6 and 1.0 with three wave steepness ratios at three ship speeds of 13.5, 14.5 and 15.5 knots (design speed). In the case of λ/LPP = 0.6 at design speed, two more wave steepness ratios have been taken into consideration. The indirect methods have been evaluated through comparing the speed-power-rpm relationships with those obtained from the resistance and self-propulsion tests in calm water and in waves. The load variation method has been applied to predict propulsive performances in waves, and to derive overload factors (ITTC, 2018). The overload factors have been applied to obtain propulsive efficiency and propeller revolution. The thrust and revolution method (ITTC, 2014) has been modified.

• Journal of Pharmaceutical Investigation
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• 제36권6호
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• pp.421-435
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• 2006

The objective of this report is to introduce the European Union's variation rules governing medicinal products that are subject to post-approval changes. The EMEA outlines a variety of changes occurring to approved medicinal products. It also recommends a marketing authorisation holder to follow specific post-approval applications in various situations. For instance, the Commission Regulation(EC) No. 1085/2003 explains variation types and suggests post-authorisation procedures with which an applicant should comply. In all cases of minor and major variations the applicant has to investigate and validate whether or not the intended changes would have impact on the safety, efficacy and quality of a drug product. The applicant should then submit to the EMEA a variation application with adequate documentation in support of the notified changes. This procedure is implemented to ensure that changes to the approved medicinal product do not cause my public health concerns. In fact, the post-authorisation guidance categorizes post-approval changes into type IA/IB variations, type II variations, and extension applications. Such classifications determine administrative procedures to be followed in an efficient manner. Based on the type of a variation, the regulatory agency opts to reduce or extend the evaluation time-frame. The thrust of the EU's post-authorisation guidance is introduced in text with appropriate explanation. All these information will be likely to be helpful in updating a Korean regulatory guidance that could better deal with post-approval changes to generic drugs available in the market.

• 한국항공우주학회지
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• 제42권2호
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• pp.144-149
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• 2014

우주발사체 자세제어용 하이드라진 추력기의 추력실 특성길이($L^*$) 변화에 따른 연소성능을 확인하기 위해 개발모델 추력기에 대한 지상연소시험을 수행하였다. 각각의 추력기에 대한 성능특성이 추진제 주입압력 2.41 MPa (350 psia)에서의 정상상태 추력, 비추력, 응답특성 및 특성속도 등과 같은 성능변수로 분석되었다. 시험결과, 표준모델 대비 추력실 특성길이의 증가와 감소에 따라 특성속도 및 비추력성능이 공히 감소하였던 바, 표준모델의 추력실 형상이 요구성능에 대하여 가장 적합하게 설계되었다는 사실이 확인되었다.