• Wind and Structures
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• 제23권4호
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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.

• 한국작물학회지
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• 제51권4호
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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

• 한국자원식물학회지
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• 제19권3호
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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.

• 산업기술연구
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• 제25권B호
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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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• 한국가시화정보학회 2007년도 추계학술대회
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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.

• 한국작물학회지
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• 제34권3호
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• pp.270-273
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• 1989

벼 품종의 관수저항성 관련 특성을 검토코자 24일묘를 3일간 관수처리하여 뿌리와 엽신의 POD 비활성도 및 POD 동위효소들을 PAGIF법으로 전기영동하여 본 결과 관수저항성이 상대적으로 약한 일본형품종들은 통일형이나 인도형품종들보다 POD 비활성도가 높았으며 또한 관수처리로 일본형품종들의 엽신부에서는 무관수시 어느 부위에서도 나타나지 않았던 POD 동위효소의 특이 band가 등전점 9부근에서 출현하였다.

• 대한조선학회논문집
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• 제42권3호
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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.

• 한국강구조학회 논문집
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• 제20권6호
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• pp.751-759
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• 2008

본 연구에서는 구조적 기본단면인 사각단면중에서 B/D=2,3,4,5 단면을 대상으로 단면주위 흐름상태가 단면의 공기력 특성에 미치는 영향을 살펴보고, 정지/진동하는 B/D=4 사각실린더 주위의 비정상압력장에 POD해석을 도입함으로써 흐름패턴에 따른 POD해석의 고유벡터를 규정하고 실린더 주위 흐름장 안에 공존하는 서로 다른 흐름패턴의 상호간섭과 물리적 모드분해에 관하여 검토하였다. POD해석의 고유벡터 비교를 통해서 칼만와류는 박리버블에 의해서 거의 영향받지 않지만 칼만와류는 단면후류부에서 박리버블의 발달에 상당히 간섭하고 있음을 확인하 였다. 변장비(B/D=2,34,5) 변화에 따른 ${dC_L/d\alpha}$, ${H_1^{*}}$의 정(+)부(-)의 차이, 즉 갤로핑현상에 대한 안정/불안정성은 박리전단층의 재부착에 깊은 관련이 있는 것으로 판단되며 B/D=3,4에서 시간평균적으로 재부착하던 주위흐름장이 칼만와류의 방출을 제어하면 재부착하지 않는 것으로 생각된다. 즉, 칼만와류의 억제는 후류부에서 박리전단층의 곡률이 작아지도록 간섭하고 단면에 있어서 elongation효과를 나타낸다.

• 대한기계학회논문집B
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• 제37권6호
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• pp.567-575
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• 2013

외부경계층 수직 날의 마찰저항 저감 기구를 규명하기 위하여 회류수조에서 시간분해 입자영상유속계로 측정된 비정상 유동장에 POD 분석을 실시하였다. 최근의 PIV 결과에서는 수직날 평면 및 수직날 사이 평면에서 각각 2.73%, 7.95%의 마찰저항 저감효과가 발견되었다. 본 연구에서는 수직날 배열이 난류조직구조에 미치는 영향을 POD 방법을 통하여 분석하였다. 난류유동의 조직적인 와구조가 수직날에 의하여 절단, 변형되고 비정상 거동이 난류경계층에서의 마찰저항 저감 기구와 밀접하게 관련된 것으로 관찰되었다.

• Journal of Biosystems Engineering
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• 제27권2호
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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.