• 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 the Korea Institute of Military Science and Technology
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• v.22 no.4
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• pp.501-508
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• 2019

In this paper, a study on a wireless check-up method of test equipment for captive flight test(CFT) was conducted. For CFT, test equipment is mounted on a POD, and check-up is carried on the test equipment's. For check-up the POD wirelessly, battery, power distribution unit, wireless communication devices were designed within the POD, and a check-up device is designed outside of the POD. Once the external check-up device sends a 'start signal' to the POD, it performs the overall check-up procedures and transmits the 'end signal' to the external check-up device. Detailed check-up results are stored in an internal storage device, and are possible to read from external check-up device if necessary, thereby improving the reliability of the wireless check-up. By implementing and applying these wireless check-up system, the reliability of the check-up was enhanced by dynamical and movable check-up, and safety is guaranteed as the check-up was carried without access to the aircraft.

• Journal of Astronomy and Space Sciences
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• v.35 no.4
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• pp.243-252
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• 2018

In a satellite gravimetry mission similar to GRACE, the precision of inter-satellite ranging is one of the key factors affecting the quality of gravity field recovery. In this paper, the impact of ranging precision on the accuracy of recovered geopotential coefficients is analyzed. Simulated precise orbit determination (POD) data and inter-satellite range data of formation-flying satellites containing white noise were generated, and geopotential coefficients were recovered from these simulated data sets using the crude acceleration approach. The accuracy of the recovered coefficients was quantitatively compared between data sets encompassing different ranging precisions. From this analysis, a rough prediction of the accuracy of geopotential coefficients could be obtained from the hypothetical mission. For a given POD precision, a ranging measurement precision that matches the POD precision was determined. Since the purpose of adopting inter-satellite ranging in a gravimetry mission is to overcome the imprecision of determining orbits, ranging measurements should be more precise than POD. For that reason, it can be concluded that this critical ranging precision matching the POD precision can serve as the minimum precision requirement for an on-board ranging device. Although the result obtained herein is about a very particular case, this methodology can also be applied in cases where different parameters are used.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.918-927
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• 2020

Flows induced by hybrid CRP pod propulsion systems (CRP-POD) are fundamentally characterized by unsteadiness. This work presents a numerical study on the unsteady flow of a CRP-POD at behind-hull condition based on CFD (Computational Fluid Dynamics). Unsteady RANS method is adopted, coupled with SST k-u turbulence model and sliding mesh method. The propeller thrusts and torques obtained by CFD is validated by model tests and acceptable agreements are obtained. The time histories of shingle-blade loads and pressures near the hull surface are recorded for the analysis of unsteady flow features. The cases of forward propeller alone and aft propeller alone are also computed to distinguish the hull-propeller interaction and propeller-propeller interaction. The results show the blade loads of both forward and aft propellers strongly fluctuate with phase angles. For the forward propeller, the blade load fluctuation is mainly governed by the hull-propeller interaction, while the aft blade load is remarkably affected by the propeller-propeller interaction in terms of the load average and fluctuation pattern. The fields of pressure, vorticity and velocity are also analyzed to reveal the unsteady flow features.

• Wind and Structures
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• v.34 no.1
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• pp.29-42
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• 2022

Following the BARC initiative, wind tunnel measurements have been performed on a 5:1 rectangular cylinder. Pressure distribution has been measured in several sections, checking the two-dimensionality of the flow around the model. Mean values compare well with previous data. These measurements have been processed using the standard Proper Orthogonal Decomposition (POD) and the snapshot POD to obtain phase-resolved cycles. This decomposition has been used to analyze the characteristics of the flow around the cylinder, in particular, the behavior of the recirculation bubble in the upper/lower surfaces. The effect of the angle of attack, the turbulence intensity and the Reynolds number has been studied. First and second modes extracted from POD have been found to be related to the reattachment of the flow in the upper surface. Increasing the angle of attack is related to a delay in the reattachment position, while an increase in turbulence intensity makes the reattachment point to move towards the windward face.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.22 no.2
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• pp.93-97
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• 1977

The rate of damaged soybean seeds by pod borer averaged 7.4% with the range of 1.2%-21.3% and tended to be higher in the lines with hairy pods comparing to those with hairless pods. The susceptibility of pod borer was negatively correlated with the pod setting date. while was not significantly affected by the weather conditions during the pod setting period.

• 프린팅코리아
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• v.11 no.2
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• pp.106-109
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• 2012

한국출판협동조합(이사장 김중영), 출판유통진흥원(회장 김종수)은 구랍 1일 서울 마포구 서강동 주민센터에서 <출판 경영에 있어서 POD의 활용성>에 대한세미나를 열었다. 이날 행사에는 100여 인쇄, 출판업계 관계자들이 참석해 최근들어 높아진 POD출판에 대한 관심을 보여주었다. 이번 세미나에서 신구대 그래픽아츠미디어과 오성상 교수가 발표한 <디지털인쇄로 인한 출판의 미래>의 주요 내용을 소개한다.

• 프린팅코리아
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• v.8 no.3
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• pp.84-85
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• 2009

IT기술과 인쇄기계가 결합되는 사례가 적지 않은 요즘이지만 패키지나 번들 수준을 벗어나서 1:1 맞춤형으로 제공되는 사례나 아예 전적으로 집중하는 사례는 그리 흔하지 않은 것이 사실이다. 지난 1987년 출범한 대신정보통신(대표 이재원, www.dsic.co.kr)은 IT기술을 기반으로 하는 전형적인 정보통신분야의 회사이지만 IT기술과 시스템프린터를 융합한 고객맞춤형 디지털프린팅사업을 하는 POD사업본부(본부장 김종배이사)는 많은 고객을 확보, 활발한 사업을 전개하고 있다. POD사업본부는 특화 및 차별화된 상품 및 서비스 개발에 역점을 기울여 왔으며 오세코리아, 다이니폰스 크린코리아, 리코 등 유력한 프린터 제조사들과 협력관계를 맺고 다양하고 생산성 높은 작업을 지원하는 시스템 프린터와 토탈 Out_put 솔루션을 제공해 왔다.

• International Journal of High-Rise Buildings
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• v.11 no.4
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• pp.277-286
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• 2022

In this study, The POD technique was applied to the fluctuating wind pressure of high aspect ratio circular cylinder to consider about its organizational structure, and considered about the characteristics of the fluctuating wind force obtained by synthesized the POD modes.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.4
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• pp.327-332
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• 2012

International Towing Tank Conference (ITTC) recommended verifying a ship's ability to move transversely at zero forward speed without altering heading by a crabbing test. In sea trial, all available propellers/rudders/thrusters should be used to find the maximum possible transverse speed. For estimating crabbing ability in the design stage, tests to estimate possible swaying force and yawing moment range using all available propellers/rudders/thrusters are conducted. By butterfly diagram, which compares possible swaying force and yawing moment range with external swaying force and yawing moment by wind, a ship's crabbing ability can be estimated. In this study, model tests of a cruise vessel equipped with bow thrusters and POD system were conducted to find out her crabbing ability in the design stage. To mimic quay condition, a model quay-wall was set in the towing tank.