• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.6
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• pp.472-477
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• 2023

In this paper, we proposes the use of Model Predictive Control (MPC) techniques to enable quadcopter drones to effectively follow paths and maintain flight safety even under dynamic external environments and disturbances. Through simulations conducted in MATLAB/Simulink, the performance of two controllers, PID and MPC, is compared in flight scenarios with disturbances. The proposed design method shows that the MPC controller, when compared to the PID controller, exhibits a difference in the Mean Squared Error between the intended flight path and the actual path of the quadcopter drone. This difference is 0.2 in performance under no disturbance, and it increases to 0.8 under disturbance, demonstrating the improved path following accuracy of the MPC controller.

• Journal of Radiation Protection and Research
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• v.16 no.2
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• pp.67-74
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• 1991

Parameter uncertainty and sensitivity of KFOOD model for calculating the ingestion dose via terrestrial food-chain pathway was analyzed with using Monte-Carlo approach. For the rice ingestion pathway, estimated values from KFOOD code were very conservative. Most sensitive input parameters in model were deposition velocities and soil-to-plant transfer coefficient of radionuclides.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.12
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• pp.989-996
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• 2021

In the case of an unmanned aerial vehicle using a battery as a power source, there are restrictions in performing the mission because the battery capacity is limited. To extend the mission capability, it is important to minimize battery usage while the flight to the mission area. In addition, by using the battery usage prediction model, the possibility of mission completeness can be determined and it can be a criterion for selecting an emergent landing point in the mission planning stage. In this paper, we propose a battery usage prediction model considering as one of the environmental factors in the three-dimensional space. The required power is calculated according to the flight geometry of an unmanned aerial vehicle. True battery usage which is predicted from the required power is verified through the comparison with the battery usage prediction model. The optimal flight trajectory that minimizes battery usage is produced and compared with the shortest travel distance.

• Journal of Navigation and Port Research
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• v.36 no.5
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• pp.395-400
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• 2012

The stress-strain relationship of soil is dependent on a number of factors such as soil type, density, stress level and stress path. Th accurate stress-stain relationship can be predict using a constitutive model incorporated all influencing factors. In this study, an isotropic compression-expansion test and a series of drained conventional triaxial tests with several stress paths were performed on Baekma river sand to investigate parameters characteristics of Lade's single work hardening model depending on the stress path.. Based on test results, the parameters of yield function (h, ${\alpha}$) are not much influenced by stress level and stress path, the these parameters do affect a little bit of stress-strain behavior. The parameters h and ${\alpha}$ are closely related to failure criterion ${\eta}_1$, they can be replaced by failure criterion parament. We also observed that predicted values from the Lade's single hardening constitutive model are well matched with the observed data.

• Journal of the Korean Society for Marine Environment & Energy
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• v.2 no.2
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• pp.78-85
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• 1999

Tracking model of a drifted ship lot the search and rescue mission in southern sea of Korea is studied. In this model, search area is determined by considering standard deviation of position around reference point. The reference point is estimated for a given type of ship when marine environmental conditions such as wind and current are given. A database for environmental data, which is necessary for the real-lime tracking of drilled ship, is gel)elated on southern sea and western sea of Korea. Using this database, the real-time prediction of wind and current is possible. The simulated trajectories and search area of our model ate validated by comparing with reported real data.

• Journal of IKEEE
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• v.24 no.4
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• pp.1176-1179
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• 2020

Vessel path prediction methods generally predict the latitude and longitude of a future location directly. However, in the case of direct prediction, errors could be large since the possible output range is too broad. In addition, error accumulation could occur since recurrent neural networks-based methods employ previous predicted data to forecast future data. In this paper, we propose a vessel path prediction method that does not directly predict the longitude and latitude. Instead, the proposed method predicts the acceleration of the vessel. Then the acceleration is employed to generate the velocity and direction, and the values decide the longitude and latitude of the future location. In the experiment, we show that the proposed method makes smaller errors than the direct prediction method, while both methods employ the same model.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.726-731
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• 2002

The purpose of this paper is to analyze the path loss for the mobile cellular system. The maximum distance is 150 km and the area is about 6,000 $\textrm{km}^2$ and the field test was performed for the total 5 base stations. The path loss was calculated by Hata and Okumura models, respectively. As a result, it was shown that a proper model for the field test data is the middle one between the rural model and suburban/rural Hata model.

• The Journal of the Acoustical Society of Korea
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• v.21 no.8
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• pp.679-685
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• 2002

Low-frequency mono-static reverberation model for shallow-water environment is presented. It is necessary to develop the transmission loss model to calculate the sub-bottom interaction because the ray-based transmission loss model is difficult to compute the pressure accurately which penetrates the bottom medium. In this paper reverberation level is calculated using the RAM (Range dependent Acoustic Model) to augment the multi-path expansion model because it does not estimate transmission loss accurately in shallow water. The signals generated by the L-HYREV and the GSM are compared with the observed signals and it is showed that the L-HYREV model provides a closer fit to the observed signals than those obtained using the GSM.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.355-357
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• 2022

In this paper, as a positioning technology for predicting the movement path of a moving object using a recurrent neural network (RNN) model, which is a deep learning network, in an indoor environment, continuous location information is used to predict the path of a moving vehicle within a local path. We propose a movement path generation technique that can reduce decision errors. In the case of an indoor environment where GPS information is not available, the data set must be continuous and sequential in order to apply the RNN model. However, Wi-Fi radio fingerprint data cannot be used as RNN data because continuity is not guaranteed as characteristic information about a specific location at the time of collection. Therefore, we propose a movement path generation technique for a vehicle moving a local path in an indoor environment by giving the necessary sequential location continuity to the RNN model.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.3
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• pp.11-21
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• 2000

을 합하여 얻을 수 있다. 이와 같은 광선 추적법을 적용한 해석적 방법은 디지털 방송의 수신 영역을 결정하는 중요한 두 요소인 수신 전계강도 및 다중 경로 간섭을 비교적 정확히 예측할 수 있다. 개발된 모델을 이용하여 디지털 방송 환경에서 동일채널 중계기로 인한 방송 수신 영역의 확대 또는 축소를 예측할 수 있으며, 중계기의 최적화 위치를 찾는 데 활용할 수 있다.