• 한국가시화정보학회지
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• 제15권3호
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• pp.52-56
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• 2017

In this study, we investigate the flow characteristics of lift-type disk which behaves the up-down motion using the large eddy simulation (LES) and immersed boundary method (IBM). Also, we perform the noise analysis using pressure field at 1.35 m distance and reveal the cause of noise to observe the vortical structure analysis of flow result. It is observed that vortical structure and wind shear were generated at leading edge and tower with high velocity deficit and flow separation. High magnitude of flow noise was observed in low frequency range which is from 30 Hz to 60 Hz. It was observed that vortical structure at leading edge was generated in frequency range from 33.3 Hz to 41.6 Hz. Temporal characteristic in vortical structure at leading edge was similar to noise characteristics, having the similar frequency ranges.

• 설비공학논문집
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• 제21권12호
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• pp.695-702
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• 2009

Dynamic behavior of Libr-water absorption system using low-temperature hot water was investigated numerically. Thermal-hydraulic model of single-effect/double-lift 100 RT chiller was developed by applying transient conservation equations of total mass, Libr mass, energy and momentum to each component. Transient variations of system properties and transport variables were analysed during start-up operation. Numerical analysis were performed to quantify the effects of bulk concentration and part-load operation on the system performance in terms of cooling capacity, coefficient of performance, and time constant of system. For an absorption chiller considered in the present study, optimum bulk concentration was found to exist, which resulted in the minimum time constant with stable cooling capacity. COP and time constant increased as the load decreased down to 40%, below which the time constant increased abruptly and COP decreased as the load decreased further.

• 한국항공우주학회지
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• 제42권1호
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• pp.59-66
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• 2014

프로펠러 추진 항공기의 경우, 프로펠러 power-on 효과는 항공기의 비행성능 및 조종안 정성에 직간접적으로 커다란 영향을 미친다. 본 연구에서는 CFD 기반의 multiple reference frame과 sliding mesh model을 이용하여 power-on 효과가 항공기의 공력특성에 미치는 영향을 해석하였다. 프로펠러 power-on 효과에 의해 양력이 미소하게 증가하고 최대양력이 증가되며 실속이 지연된다. 반면, 프로펠러 power-on 효과에 의해 항력이 크게 증가하여 양항비가 감소된다. 또한, 프로펠러 power-on 효과에 의해 기수내림 피칭 모멘트가 감소하여 종방향 정안정성이 감소된다. 본 연구를 통해 획득한 프로펠러 power-on 해석결과는 항공기 성능 및 조종안정성 해석에 중요한 자료로 활용되어 추진식 프로펠러 항공기 개발에 기여할 수 있을 것으로 기대된다.

• 물과 미래
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• 제35권5호
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• pp.51-59
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• 2002

In recent years the human impact on the environment becomes increasing lift threatening, calls for the better management of resources. In field of water quality of river flow, the best way to conserve water quality is specific efforts to control the pollutant loadings and treat the loadings in the basin to reduce the discharge of pollutant loadings to river. But in general the water quality influenced by the dam discharge. Especially in dry season, it is more dominant way to improve the water quality which contaminated with the pollutant loadings from the basin. The dam discharge amounts of the 2 dams in the Keum River that maintain the down stream water quality were estimated for the year of 1999, 2001, 2006, 2011, in case of irrigation and non-irrigation seasons. The pollutant loadings for the basin are estimated with the planning of treatment plants construction schedule for every sub-basins. The river flow rates were considered low flow as 2.33 year low flow and 10 year low flow. The QUAL2E model was used as a tool of simulation.

• 한국항공우주학회지
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• 제34권7호
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• pp.12-17
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• 2006

채널 및 레일과 같은 비평면 지면 위를 비행하는 날개들의 정상상태 공력특성 및 종방향 정안정성을 경계요소법을 사용하여 연구하였다. 펜스의 높이가 날개의 위치보다 높을 경우, 펜스와 날개와의 거리가 작아질수록 양력이 증가하고 피칭다운 모멘트가 커졌다. 레일의 폭이 날개 스팬보다 넓을 때, 레일의 높이가 낮을수록 양력이 증가하고 유도항력이 감소하였다. 종방향 정안정성 측면에서 단일 날개의 경우 비평면 지면보다 평지에서 안정한 결과를 나타내었다. 종렬배치형 날개의 경우 채널내를 비행하는 날개가 평지보다 비평면 지면에서 안정적이었다. 본 연구결과는 초고속운송체의 설계에 적용될 수 있을 것으로 기대한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.525-530
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• 2013

With the increasing the importance of emotional quality of vehicle, the sound quality of systems with electric motor components has become increasingly important. Electric motors are used for windows, seats, sun roof, mirrors, steering columns, windshield wiper, climate control blowers, etc. In this paper, a study was conducted to identify sound quality factors that contribute to customer's satisfaction and preference of the window lift system. Jury test for subjective evaluation was carried out and sound quality index was developed. Averaged sound pressure level and sharpness were significant factors when glass moves down. Also, maximum loudness at stop section and averaged loudness were significant factor when glass moves up. Noise source identification was carried out for the reduced the loudness and sharpness during glass transferred section and impulsive noise at stop section, Using the source identification result, several improvement points were applied. And finally, the degree of sound quality improvement was judged using sound quality index.

• 항공우주기술
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• 제11권2호
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• pp.65-72
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• 2012

프로펠러와 고양력장치를 장착한 터보프롭 항공기에 대한 실속 특성 분석을 위해 수치 해석을 수행하였다. 항공기의 실속 특성은 프로펠러와 고양력 장치의 장착 조합에 따른 형상별 전산해석 결과를 통해 정성적으로 분석하였다. 실속 특성 해석은 Spalart-Allmaras 난류 모델을 기반으로 한 3차원 Navier-Stokes 방정식 해법을 이용하였으며 프로펠러의 회전은 슬라이딩 격자기법을 이용하여 모사하였다. 분석 결과 순항 형상의 경우 동체/날개 페어링에서 주요 유동박리가 발생하며 프로펠러 후류로 인해 점차 감소함을 알 수 있었다. 고양력장치를 장착한 경우 나셀 바깥쪽에서 주요 유동박리 현상이 발생하였고 프로펠러가 회전하는 경우에도 상대속도 감소와 유효 받음각 증가로 나셀 바깥쪽 날개 부분은 조기에 실속에 잠김을 알 수 있었다. 프로펠러는 날개의 inboard에서 하강하는 회전 방향이 프로펠러 후류로 인한 실속 지연 측면에서 유리함을 알 수 있었다.

• 한국콘텐츠학회논문지
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• 제15권5호
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• pp.18-26
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• 2015

본 논문에서는 다양한 무대연출이 가능한 전(Omni)방향 이동무대와 수직 상승 무대로 구성된 복합형 무대 시스템의 설계 및 제어 방법에 대해 제안하였다. 복합 무대 시스템은 전후/좌우/회전 등 3 자유도 모션의 이동무대와 1 자유도 상/하 모션의 상승 무대 등 총 4 자유도 동작이 가능하도록 개발 되었다. 이동무대는 2개의 구동 휠과 조향 휠 구조로 설계하여 기존 차동 방식의 이동무대에 비해 기동성을 높였으며, 상승무대는 전고대비 수식 상승비가 10배 이상 가능하도록 맞물림 방식의 구조로 설계하였다. 또한, 공연연출에 필요한 모션 구현을 위해 경로계획 방법과 계획된 경로를 추종하기 위한 제어방법에 대해서도 제안하였다. 그리고 복합형 무대 시스템의 수평 이동 및 수식 상승 등 복합 모션 실험을 통해 그 성능을 검증하였으며, 공연 공간 디자인 도록을 제시하여 개발된 시스템이 공연에서 다양한 연출에 활용이 가능함을 보였다.

• Ocean Systems Engineering
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• 제6권2호
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• pp.143-159
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• 2016

Cargo, such as a Tension Leg Platform (TLP), Semi-submersible platform (Semi), Spar or a circular Floating Production Storage and Offloading (FPSO), are frequently dry-transported on a Heavy Lift Vessel (HLV) from the point of construction to the point of installation. The voyage can span months and the overhanging portions of the hull can be subject to frequent wave slamming events in rough weather. Tie-downs or sea-fastening are usually provided to ensure the safety of the cargo during the voyage and to keep the extreme responses of the cargo, primarily for the installed equipment and facilities, within the design limits. The proper design of the tie-down is dependent on the accurate prediction of the wave slamming loads the cargo will experience during the voyage. This is a difficult task and model testing is a widely accepted and adopted method to obtain reliable sea-fastening loads and extreme accelerations. However, it is crucial to realize the difference in the inherent stiffness of the instrument that is used to measure the tri-axial sea fastening loads and the prototype design of the tie-downs. It is practically not possible to scale the tri-axial load measuring instrument stiffness to reflect the real tie-down stiffness during tests. A correlation method is required to systematically and consistently account for the stiffness differences and correct the measured results. Direct application of the measured load tends to be conservative and lead to over-design that can reflect on the overall cost and schedule of the project. The objective here is to employ the established correlation method to provide proper high-frequency responses to topsides and hull design teams. In addition, guidance for optimizing tie-down design to avoid damage to the installed equipment, facilities and structural members can be provided.

• 대한한의학원전학회지
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• 제3권
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• pp.151-217
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• 1989

In this thesis, I intend to study the translational and clinical interpretation through the theory of Ja-Yeol, and reached the following conclusions. 1. Liver-Heat-Disease due to absess of the function of expelling and lifting off, that Liver-Yang cannot lift up to upper-warmer, and stagnate liver. I think the symptoms of yellowish urine, abdominal pain, somnolence, fever belong to the syndrome of 'Gi-Bun(氣分)', and the symptoms of ravings with surprising, distending pain of hypochondrium, restless involuntary movement of the limbs, unable to lie flat belong to the syndrome of 'Hyeol-Bun(血分)'. 2. Heart-Heat-Disease due that 'Eum-Gi(陰氣)' in heart cannot lay down and reach to stagnate at heart, inner part. I think the symptoms of unjoy, acute cardiac pain, fidgetiness, well-nausea, headeche, reddish face, anhidrosis, etc. reveal with Heart-Heat-Disease. 3. Spleen-Beat-Disease due that 'Eum-Gi' in spleen cannot lay down and Yin of spleen changs heat. I think the symptoms of heaviness of head, cheek pain, fidgetiness, cyanosis, well-nausea, fever, not to let flex and reflex with back pain, diarrhea with abdominal pain, left and right cheek pain reveal with Spleen-Heat-Disease. I think symptoms of fever, diarrhea with abdominal pain belong to the syndrome of Yin-exhausion. 4. Lung-Heat-Disease due to that 'Eum-Gi' in lung cannot lay down. When 'Wi-Gi(衛氣)' stagnates at external part, I think, the symptoms of intolerance to wind and cold, yellowish fur, fever reveal. When Wi-Gi stagnates at lung, inner part, I think, the symptoms of dispnea with cough, pain on chest and back, unable to breath deeply, hydrosis and chilling reveal. 5. Kidney-Heat-Disease, in that the symptoms of back pain, leg aching, extreme thirst and frequently drink, fever, pain and stiffness of nape, cooling and aching leg, heat on plantar pedis, not trying to speak reveal is regarded external heat disease of 'Tai-Yang-Gyeong's(太陽經)' disease that asthenic fever open 'Tai-Yang-Gyeong' and lift by not enough of 'Yang-Gi(陽氣)' lifeing up from Kidney space, the water space of five elements.