• The Journal of the Acoustical Society of Korea
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• v.32 no.5
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• pp.369-376
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• 2013

Using Lowson's acoustic analogy, low frequency noise of a wind turbine (WT) is predicted in time domain and the noise sources contributing to the low frequency noise is analyzed. To compute averaged pressure distribution on blades of the WT as noise source, XFOIL is utilized. The blade source domain is divided into several segments along the span direction to compute force exerted on air surrounding the blade segments, which is used as input for noise prediction. The noise sources are decomposed into three terms of force fluctuation, acceleration and velocity terms and are analyzed to investigate each spectral contribution. Finally, predicted spectra are compared with measured low frequency noise spectrum of a wind turbine in operation. It is found that the force fluctuation component contributes strongly in low frequency range with increasing wind speed.

• Current Industrial and Technological Trends in Aerospace
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• v.9 no.1
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• pp.37-42
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• 2011

Korea's space activity is expected more vital in the next decade. 14 Korean government satellites, with 10 satellites more over the last decade, are planned for launch between 2011 and 2020 according to the national space long-term plan. And Korean Space Launch Vehicle 2 has been developing aiming to launch in 2021. Forecasting and supply planning for the Korea Aerospace Research Institute's manpower could be essential to successfully fulfill the Korea's next decadal task in the aerospace field. In this paper, KARI's manpower is forecasted using the relations between KARI's budget and total personnel. KARI is expected to has 1,000~1,400 personnel in 2020 which is at least 400 personnels more than present.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.1094-1095
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• 2023

우리나라는 지리적 여건 상 대외무역에 대한 의존도가 높기 때문에, 해상운송에서의 물동량을 예측하여 항만시설을 개발하는 것이 매우 중요하다. 한편 우리나라 컨테이너 운송의 75%는 부산항을 통해 운송되고 있기 때문에 경기 회복을 위해서는 부산항의 경쟁력 강화가 급선무이다. [1] 물동량은 경제적 수입 뿐만 아니라, 지속가능성을 예측하는 측면에서도 가치가 있다. 본 연구에서는 물동량, 경제지수, 기후정보 등 다양한 입력변수와 LSTM 모델을 이용하여 보다 정확한 부산항 컨테이너 물동량 딥러닝 예측모델을 구현하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1447-1454
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• 2013

In this study, we developed the equation of ship wave crests in intermediate as well as deep waters by extending Kelvin's (1887) theory using the recursive relation for the dispersion relation. The present equation can be applied for varying water depth as well as constant water depth. Using FLOW-3D we conducted numerical experiments to verify analytical prediction. The ship wave crest patterns became asymmetric on a plane slope when the ship propagates alongshore direction. That is, in shallower side, wave crests tend to be parallel to the coastline due to refraction and, in deeper side, wave crests tend to be orthogonal due to reverse refraction.

• The Journal of Bigdata
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• v.6 no.2
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• pp.85-98
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• 2021

The pandemic of COVID-19 further promoted the imbalance in the volume of imports and exports among countries using containers, which worsened the shortage of empty containers. Since it is important to secure as many empty containers as the appropriate demand for stable and efficient port operation, measures to predict demand for empty containers using various techniques have been studied so far. However, it was based on long-term forecasts on a monthly or annual basis rather than demand forecasts that could be used directly by ports and shipping companies. In this study, a daily and weekly prediction method using an actual artificial neural network is presented. In details, the demand forecasting model has been developed using multi-layer perceptron and multiple linear regression model. In order to overcome the limitation from the lack of data, it was manipulated considering the business process between the loaded container and empty container, which the fully-loaded container is converted to the empty container. From the result of numerical experiment, it has been developed the practically applicable forecasting model, even though it could not show the perfect accuracy.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.287-289
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• 2014

선박의 선위 추측(DR, Dead Reckoning)은 수신되거나 측정된 위치 데이터와 속력, 침로 데이터만을 반영하여 계산하므로 대양의 항해나 연근해의 해역에서는 유효할 수 있으나 침로의 변경과 선속의 변화가 잦은 항계 내의 조선에 있어서는 적용이 어렵다는 문제점이 있다. 본 논문에서 제안하는 선박의 추측위치(DRP, Dead Reckoning Position)는 선박의 운항 패턴에 따라 항계 내의 항적 데이터를 수집하고, 수신된 위치 데이터와 속력, 침로 데이터를 점장위도항법(Mercator Sailing)을 통하여 계획항로(Planned Route)의 각 변침점(WP, Waypoint)간 침로(Course)와 항정(Ship's Passage)에 반영하였다. 제안된 추측위치 산출방법을 통하여 항계 내의 조선과정에서 계획항로를 선박의 추측위치와 결합하여 특정 시간 후의 상황패턴을 미리 예측하고 관제사의 의사결정에 기여하고자 한다.

• Journal of Navigation and Port Research
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• v.38 no.6
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• pp.701-708
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• 2014

This study is aimed to obtain the influence of port hinterlands on container cargo volumes of Incheon port using System Dynamics(SD). Also, macro economic index such as exchange rates(US dollar), balance of current account, capital balance, Japan trade, China trade, export unit value index, import unit value index, total turnover of Incheon port were used as the factors that influence container cargo volumes of Incheon port. Moreover micro index regarding port hinterlands' operating companies such as total sales, rental fee, number of employees were introduced in the simulation model. In order to measure accuracy of the simulation, this study implemented MAPE analysis. And after the implementation, the simulation was decided as a much more accurate model because MAPE value was calculated to be within 10%. This study respectively examined factors using the sensitivity analysis. As a result, in terms of the effects on cargo volume in Incheon Port, the factor named 'cargo volumes of port hinterlands' operating companies' is most significant. And increasing the rental fee of hinterland was resulted in decreasing the cargo volumes of Incheon port.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.6
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• pp.663-670
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• 2014

The Pyeongtaek port is expected lack of waiting anchorage due to increase of incoming ships whit increasing of trading volume in the near future. In case of an anchorage facility's structural alternations and expansion, it should be considered comprehensively how it affects other anchorage facilities. In addition, the volume of ship traffic to relevant area should be estimated accurately and then the facility's scale is calculated. In this paper, researchers calculated cargo per unit ship with the throughput for every ship and predicted the number of ships which had entered Pyeongtaek port. As a result, the port's ability to be docked was predicted to be not enough in 2030. It will exceed the number of ships able to cast anchor at specific two parts simultaneously 12.6 and 1.6 respectively consequently, the necessity to expand the ports was suggested. Hence, the best expansion plan was examined with analysis of marine transportation environment at each ports and the improvements suggested are anchoring ships at Ippado anchorage is 19.7 and the one at Janganseo anchorage is 12.6.

• Nuclear Engineering and Technology
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• v.22 no.4
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• pp.315-325
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• 1990

The analytical repository source term (REPS) computer code is developed for the safety assessment of radioactive waste geologic repository. For reliable prediction of the leach rates for various radionuclides, degradation of concrete structures, corrosion rate of waste container, degree of corrosion on the container surface, and the characteristics of radionuclides are considered in this REPS code. For the validation of the radionuclide leach rates predicted by the REPS model, the calculated leach rates of Cs-137, Sr-85, and Co-60 are compared with two reported leaching test results. Cesium and strontium leach congruently, and the leaching test results of these species can be reproduced by the congruent leaching model included in the REPS model. In case of cobalt, the solid diffusion model is in good agreement with the leaching test results.

• Proceedings of the KGS Conference
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• 2003.11a
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• pp.24-28
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• 2003

장기간에 걸친 지형변화를 예측하는 것은 기초과학뿐만 아니라 응용과학 및 해양 공학적인 측면에서 볼 때 매우 중요하다. 퇴적물 이동과 지형변화의 예측은 항만의 수로를 유지하고, 폭풍에 의한 침식을 방제 할 뿐 아니라 지질학적 time-scale에서 퇴적층 형성을 이해함으로서 경제적으로 유용한 석유자원 매장을 밝히는데 도움을 준다. 그렇지만 퇴적역학에 대한 이해가 불충분하고 지형환경 system이 복잡하기 때문에 퇴적물 이동 및 지형변화에 대한3차원 모델을 통한 지형 변화 예측을 실용적으로 사용하기에는 불충분하다. (중략)