• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.26.2-26.2
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• 2008

YLPODS (Yonsei Laser-ranging Precise Orbit Determination System) is POD system using SLR (Satellite Laser Ranging) data. YLPODS is developed for two main purposes. The first purpose is to verify the result of POD using GPS data. The second purpose is to perform POD using only SLR data. In this study, YLPODS performance test is presented for checking the reliability of POD using only SLR data. To perform POD, the information of CHAMP and TOPEX mission is applied and SLR NP (Normal Point) data is used. The test is performed by checking both range precision and 3D accuracy (radial, along, cross direction). To confirm of 3D accuracy, CHAMP GENESIS orbit and TOPEX JPL orbit of NASA are used.

• 산업기술연구
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• 제28권B호
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• pp.135-141
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• 2008

In this paper, the Proper Orthogonal Decomposition (POD) method, which is a statistical analysis technique to find the modal characteristics of a structure, is adapted to identify the modal parameters of a tall chimney structure. A wind force time history, which is applied to the structure, is obtained by a wind tunnel test of a scale down model. The POD method is applied on the wind force induced responses of the structure, and the true normal modes of the structure can be obtained. The modal parameters including, natural frequency, mode shape, damping ratio and kinetic energy of the structure can be estimated accurately. With these results, it may be concluded that the POD method can be applied to obtain accurate modal parameters from the wind-induced building responses.

• 산업기술연구
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• 제24권B호
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• pp.29-36
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• 2004

The wind and wind-induced dynamic wind pressures fluctuate irregularly according to time and space. In this study, the proper orthogonal decomposition(POD) technique is applied to wind pressures acting on a tall tower model, and the following results are found: the along-wind and across-wind forces can be reconstructed by only four dominant POD modes, and the reconstructed errors are 4.71% and 22%, respectively for across-wind and along-wind directions. The physical meanings for dominant modes are also presented in the paper. The POD analysis can compress complex wind pressure data only by a few dominant modes and interpret spatio-temporal characteristics of wind pressure by novel way while existing statistical methods do not have such benefits.

• 한국군사과학기술학회지
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• 제13권1호
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• pp.164-169
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• 2010

Proper Orthogonal Decomposition (POD) is applied to the analysis of 2-dimensional cylinder wake flow. Time histories of flow variables were obtained by the incompressible CFD analysis. By using the method of snapshots the correlation matrix was constructed, and then eigenvalues, POD modes and time coefficients were calculated. Finally the flow field was reconstructed by using a few of the lower POD modes, and compared to the original ones.

• Wind and Structures
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• 제10권2호
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• pp.153-176
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• 2007

The Proper Orthogonal Decomposition (POD) is a statistical method particularly suitable and versatile for dealing with many problems concerning wind engineering and several other scientific and humanist fields. POD represents a random process as a linear combination of deterministic functions, the POD modes, modulated by uncorrelated random coefficients, the principal components. It owes its popularity to the property that only few terms of the series are usually needed to capture the most energetic coherent structures of the process, and a link often exists between each dominant mode and the main mechanisms of the phenomenon. For this reason, POD modes are normally used to identify low-dimensional subspaces appropriate for the construction of reduced models. This paper provides a state-of-the-art and some prospects on POD, with special regard to its framework and applications in wind engineering. A wide bibliography is also reported.

• Journal of Chest Surgery
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• 제13권4호
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• pp.356-363
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• 1980

Even now, the hemorrhagic syndrome after cardiac surgery with the aid or a pump oxygenator constitutes a significant problem. The purpose of this study is to postulate the possible causes of the bleeding after open hear surgery [OHS]. Fifteen consecutive OHS patients with various heart diseases were selected and platelet count, plasma fibrinogen, serum calcium level were observed pre-, intra- and post- operatively until 21 th postoperative day [POD]. The platelet count was significantly decreased with initiation of extracorporeal circulation [ECC] and continued to decrease slowly until cessation of ECC. Within 10 minutes after ECC the platelet count stared to increase. But it was significantly less than preoperative count until 5th POD. The peak count was found on 14th POD and the platelet count was gradually decreased. Plasma fibrinogen also decreased significantly during operation, but it recovered up to preoperative amount within 5 hours after termination of ECC. Thereafter it rapidly increased until 3rd POD when it reached its peak. From 3rd POD it showed slow downward slope until 21st POD, but it remained in significantly higher level than preoperative amount. Serum calcium levels showed minimum fluctuations during the whole course of study. Conclusively, the decrease in platelet count and fibrinogen amount may play a considerable role for the postoperative hemorrhage. But numerous other effects of ECC must be accounted for.

• Journal of Chest Surgery
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• 제27권9호
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• pp.738-745
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• 1994

In order to evaluate the myocardial injury in cardiac valvular and coronary surgery, variables of creatine kinase[CK], myocardial band of CK[CK-MB], lactate dehydrogenase[LDH], aspartate aminotrasferase[AST] were measured in the preoperative[Preop], the operation day[POD0], and the first[POD1], third[POD3], fifth[POD5], seventh[POD7], ninth[POD9] day after operation in 29 patients. The subjects were divided into two groups according to the diseases: group V [valvular disease, n=16] and group C[coronary artery disease, n=13]. Each group was subdivided into two subgroups according to the duration of aortic crossclamping time[ACT]; group VI[ACT 120min, n=7] and group VII[ACT>120min, n=9]; group CI[ACT 120min, n=6] and group CII[ACT>120min, n=7]. The results were as followed 1. The values of CK between group V and group C had no significant difference. The values of CK in group CII were significantly greater than those in group CI and the values of CK in group VII were significantly greater than those in group VI. 2. Percentages of CK-MB between groups had no significant difference. 3. The serum levels of LDH in group V were significantly greater than those in group C. The serum levels of LDH in group VII were significantly greater than those in group VI. 4. The serum levels of AST in group VII were significantly greater than that in group VI. We were concluded that myocardial injury was more related with the duration of aortic cross clamping time rather than the type of diseases.

• 한국항공우주학회지
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• 제38권9호
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• pp.907-913
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• 2010

본 논문에서는 공군에서 운용중인 전투기를 활용한 비행시험 수행 시 비행자료를 얻기 위한 외장형 계측시스템 개발에 대하여 서술하였다. 전투기의 외장형 계측시스템은 계측 포드와 영상 포드로 구성된다. 계측 포드는 GPS/AHRS 센서를 이용하여 전투기 비행자세, 속도 및 고도 등의 비행자료를 측정하며, 영상 포드는 2대의 고속카메라와 1대의 일반카메라를 사용하여 비행영상을 획득한다. 개발한 외장형 계측시스템은 환경시험과 지상시험, 그리고 전투기에 장착하여 비행시험을 수행함으로서 성능을 입증하였다.

• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2365-2377
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• 2017

This paper addresses two interrelated problems concerning the tracking control of pod propulsion unmanned surface vessel (USV), namely, the modeling of pod propulsion USV, and tracking controller design. First, based on MMG modeling theory, the model of pod propulsion USV is derived. Furthermore, a practical adaptive neural tracking controller is proposed by backstepping technique, neural network approximation and adaptive method. Meanwhile, unlike some existing tracking methods for surface vessel whose control algorithms suffer from "explosion of complexity", a novel neural shunting model is introduced to solve the problem. Using a Lyapunov functional, it is proven that all error signals in the system are uniformly ultimately bounded. The advantages of the paper are that first, the underactuated characteristic of pod propulsion USV is proved; second, the neural shunting model is used to solve the problem of "explosion of complexity", and this is a combination of knowledge in the field of biology and engineering; third, the developed controller is able to capture the uncertainties without the exact information of hydrodynamic damping structure and the sea disturbances. Numerical examples have been given to illustrate the performance and effectiveness of the proposed scheme.

• 한국생산제조학회지
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• 제24권3호
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• pp.342-347
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• 2015

The launcher pod for missiles capable of carrying a range of different warheads has been designed to be mounted on the tracked vehicle of the hybrid weapon system (HWS). In the development of this launcher pod, its structure was designed to be resilient to damage caused by shock and vibration, as well as preventing assembly errors due to the spring-back of the main composite cover and interfacing parts. This study investigated the design of the newly developed launcher pod, with its hybrid composite-metal structure, through simulation and experiment. Both simulation and actual experiments showed that the structure of the launcher is resilient to vibration and shock. The launcher pod was also subjected to vibration and shock tests to verify its performance.