• Wind and Structures
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• v.23 no.4
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• pp.367-383
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• 2016

The influence mechanism of mean value components, noted as $P_0$, on POD applications for complete random fields $P_C(t)$ and fluctuating random fields $P_F(t)$ are illustrated mathematically. The critical philosophy of the illustration is introduction of a new matrix, defined as the correlation function matrix of $P_0$, which connect the correlation function matrix of $P_C(t)$ and $P_F(t)$, and their POD results. Then, POD analyses for several different wind pressure fields were presented comparatively as validation. It's inevitable mathematically that the first eigenmode of $P_C(t)$ resembles the distribution of $P_0$ and the first eigenvalue of $P_C(t)$ is close to the energy of $P_0$, due to similarity of the correlation function matrixs of $P_C(t)$ and $P_0$. However, the viewpoint is not rigorous mathematically that the first mode represents the mean pressure and the following modes represent the fluctuating pressure when $P_C(t)$ are employed in POD application. When $P_C(t)$ are employed, POD results of all modes would be distorted by the mean value components, and it's impossible to identify $P_0$ and $P_F(t)$ separately. Consequently, characteristics of the fluctuating component, which is always the primary concern in wind pressure field analysis, can only be precisely identified with $P_0$ excluded in POD.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.4
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• pp.310-317
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• 2006

This study was conducted to investigate the influence of drought stress during the pod developing and seed filling stage on source-sink relationships of soybean (Glycine max). Drought treatments were imposed by withholding water at the full-pod stage, 19 days after flowering, and then limited watering was relieved at 15 days after the initiation of drought treatment. Soybean seed yield was reduced by 39% mainly due to decreased pod number under drought stress, but the 100-seed weight was relatively less reduced. In spite of the 15-day drought during the full-pod stage, soybean produced good seeds showing similar l00-seed weight, protein, starch and soluble sugar content to those from the well-watered. Although drought during the full-pod stage caused source limitations; i.e. accelerated leaf senescence and reduced leaf soluble sugars, it did not cause limitations of other source characteristics such as SGR and leaf starch level. This is because the reduction in size of sinks, such as pod and seed abortions compensated for source limitations, resulting in balanced source-sink as expressed by LAR and the ratio of leaf area to seed dry weight. Drought stress during the pod developing and seed filling stage did not disrupt the source-sink balance

• Korean Journal of Plant Resources
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• v.19 no.3
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• pp.397-400
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• 2006

The objectives of this experiment was to evaluate the effect of seeding and transplanting date on yield and quality of rapeseed experiment were conducted in the research field of Chungcheongnam Do(Taejun) Agricultural Research and Extension Services with Yudal, one of the rapeseed cultivar of different growth characteristics among the six treatments were examined and recorded. Results showed that yield components such as plant height, length of ear and pod, number of branches and pods and percentage of pod setting and seed set were highest at the plot with direct seeding in Sep. 10. In this treatment yield of seed, 1,000 grains weight and weight of $1{\ell}$ were highest. On the basis of vegetative and yield parameter of direct seeding in Sep. 10 was the best sowing date of rapeseed crop in Chungcheongnam Do region of Korea. Experiments were conducted in the research field of Chungcheongnam Do(Taejun) Agricultural Research and Extension Services with Yudal variety, which showed different growth characteristics. Yield components such as plant height, length of ear and pod, number of branches and pods and percentage of pod setting and seed set were highest at the plot with direct seeding in Sep. 10. Yield of seed, 1,000 grains weight and weight of $1{\ell}$ were highest at the direct seeding in Sep. 10. Judging from the results reported above, seemed to be direct seeding in Sep. 10.

• Journal of Industrial Technology
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• v.25 no.B
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• pp.89-97
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• 2005

Application of proper orthogonal decomposition (POD) and continuous wavelet transform (CWT) is introduced to study wind speed and building roof pressures of flow separation region. In this study, a detailed analysis of the approach wind flow, wind-induced building pressure and the relation between the two fields was carried out using the POD technique and CWT analysis. The results show potential of the application of POD and CWT in characterization of spatio-temporal and spectral properties of the approach wind and its induced dynamic pressure events. Some of findings resulting from the application of this analysis can be summarized as follows: (1) The POD first principal coordinate of the roof pressure in the separated shear layer is closely correlated with the longitudinal component of oncoming flow. (2) The CWT analysis suggests that the extreme peak pressure in the separated shear layer is due to condensed large-scale eddy motions.

• 한국가시화정보학회:학술대회논문집
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• 2007.11a
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• pp.97-100
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• 2007

A new evaluation method for the performance tests of the frozen air in a refrigerator using PIV(Particle Imaging Velocimetry) and POD(Proper Orthogonal Decomposition) techniques is introduced. A two-door refrigerator model was tested for the experiments. Actual temperature measurements were carried out for the drawer No.4 in refrigerator. By evaluating the characteristics of the interior flow of the refrigerator, an optimal shape of the drawer could be suggested through the PIV evaluation test. In this research, in order to find influences the turbulent kinetic energy contribution associated with the dynamic structures, we executed a POD analysis using the method of snapshots and the instantaneous fluctuating velocity field.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.3
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• pp.270-273
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• 1989

This study was carried out to know the physiological characteristics related to flooding tolerance of rice plants. Peroxidase specific activities and banding pattern of peroxidase isozyme of 24 days old seedlings were analyzed after 3 days of flooding treatment in the artificial flooding tank. Peroxidase activities of japonica rice varieties which were relatively susceptible to submergence were higher in comparison to those of Tongil and indica rice varieties. And a peculier band of peroxidase isozyme which was not shown in any part of rice plant if not flooded, was appeared at the around 9 of isoelectric point in the leaf blade of japonica rice varieties when flooded.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.3
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• pp.290-298
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• 2005

A study of design and analysis for the POD type waterjet is conducted. The analysis and design of waterjet system are more difficult than that of conventional propulsor because waterjet is complicatedly composed of many parts which are impeller, stator, inlet, nozzle, etc. The streamline method is traditionally used in the design of pump whose characteristics are similar to those of waterjet. This streamline method, however, has some limitation in analysis of a viscous flow as well as the interaction of inlet part of hull. In the present study, the developed CFD program is applied to the analysis of POD type waterjet. The developed program is first validated by comparing the existed experimental results. The designed waterjet system is also analyzed by the developed CFD program and analyzed results show that the performance of the present POD type waterjet is above the requirement.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.751-759
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• 2008

In this study, the effect of an unsteady flow field around a body of aerostatic/aerodynamic forces were investigated using rectangular cylinders (B/D = 2, 3, 4, 5). Proper orthogonal decomposition (POD) was introduced to the analysis of the fluctuating pressure field that was measured on the stationary/oscillatory B/D=4 rectangular cylinder, and the characteristics of the proper functions with flow patterns were identified. In addition, the physical decoupling and interactions in the different co-existing flow patterns were investigated through POD. The comparison with the identified proper function associated with a particular flow pattern revealed that the Karman vortex is almost not affected by the separation bubble, but that the Karman vortex considerably interferes in the development of the separation bubble around the trailing edge. It can be considered that the Karman vortex induces the increment of the curvature of the substantial separated flow.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.6
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• pp.567-575
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• 2013

A POD analysis based on time-resolved PIV measurements in a circulating water channel has been conducted to identify the skin friction reduction mechanism of outer-layer vertical blades. A recent PIV measurement indicated 2.73% and 7.95% drag reduction in the blade plane and the blade-in-between plane, respectively. In the present study, the influence of vertical blades array upon the characteristics of the turbulent coherent structures was analyzed by the POD method. It is observed that the vortical structures are cut and deformed by the blades array and that their temporal evolution is strongly associated with the skin-friction drag reduction mechanism in the turbulent boundary layer flow.

• Journal of Biosystems Engineering
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• v.27 no.2
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• pp.89-96
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• 2002

The trend of consumption of vegetable soybeans is increasing because they are recognized as the clean vegetable. The works requiring the most intensive labor are threshing and seperation ones, and they form about 80% of total labour for vegetable soybeans production. It is necessary to develop the vegetable soybeans-thresher for the sake of cost down of vegetable soybeans production. The purpose of this study is to acquire the basic informations to design of the vegetable soybeans-thresher. We make the experimental system which control the speed of threshing cylinder and the teeth gap and investigate the detachment forces. The result are as follows ; The ratio of un-threshed soybeans-pod to stem after threshing work is decreasing as the threshing cylinder speed increases: 0.0% and 2.8% at 55m/s and 18m/s of threshing cylinder speed respectively. Also the ratio of un-threshed soybeans-pod to stem is shown as 2.0% below in the condition of 64~160mm of teeth gap and over 28m/s of threshing cylinder speed. The damaged pod ratio of detached soybeans after threshing work is decreasing as the threshing cylinder speed increases: 4.8% and 1.3% at 55m/s and 18m/s of threshing cylinder speed respectively. The minimum damaged pod ratio of detached soybeans are shown as 1.0%, 1.5% and 1.9% at 18m/s, 28m/s and 37m/s of threshing cylinder speed respectively. The average detachment forces of pods are shown as 1.5kg$_{f}$ for 3 grains, 1.2kg$_{f}$ for 2 grains and 0.8kg$_{f}$ for 1 grain respectively. The maximum detachment force of pod is shown as 2.7kg$_{f}$ for 3 grains. grains.