• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.504-508
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• 2010

The development of high voltage Insulated Gate Bipolar Transistor (IGBT) have given new device advantage in the areas where they compete with conventional GTO (Gate Turnoff Thyristor) technology. The IGBT combines the advantages of a power MOSFET (Metal-Oxide Semiconductor Field-Effect Transistor) and a bipolar power transistor. The change of electrical characteristics for IGBT is mainly coming from the change of characteristics of MOSFET at the input gate and the PNP transistors at the output. The change of threshold voltage, which is one of the important design parameters, is brought by charge trapping at the gate oxide under the environment that radiation exists. The energy loss will be also studied as the inductance values are changed. In this paper, the electrical characteristics are simulated by SPICE, and compared for variation of inductance and threshold voltage based on IGBT.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.3
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• pp.213-223
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• 2015

The helicopter initial design model was established by using the latest weight estimation equations based on the Tishchenko's methodology through the study existing initial design tools. The sequential decomposition method is used to reduce analysis time in the sizing. Empirical parameters of the weight estimation equation were also extracted from numerical and regression analysis for a helicopter database. Design input and output values were compared with the RISPECT design tool. Finally, comparison of the re-design resulting for several existing helicopters was presented and showed the good agreement within less than 5% in the weight estimation and main rotor sizing. Established initial design model was proved to be effectively used as initial design tool.

• The KIPS Transactions:PartD
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• v.18D no.3
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• pp.205-214
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• 2011

Client based web mashups have become one of the most important architecture in web application development. Although there are well known methods to generate presentation view codes for web services, navigations between views and service requests are still developed manually in most web mashups. In this paper, we propose the concept of deterministic data binding from output data to input parameters of another method. Using binding relations, we can model navigation menus for service method requests. For a given set of data mappings between services, we investigate context dependent binding conditions and discuss the generation of views and navigation menus. The proposed approach provides UI for users to navigate services of client mashup page using simple and convenient interface even when the number of services and the size of the mashup page grows. In order to show the usability of the proposed approach, we present a historic tourism service.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.5
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• pp.855-863
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• 2024

The use of Deep Neural Network (DNN) is gradually increasing in various fields due to their high efficiency in data analysis and prediction. However, as the use of deep neural networks becomes more frequent, the security threats associated with them are also increasing. In particular, if a fault occurs in the forward propagation process and activation function that can directly affect the prediction of deep neural network, it can have a fatal damage on the prediction accuracy of the model. In this paper, we performed some fault injection attacks on the forward propagation process of each layer except the input layer in a deep neural network and the Softmax function used in the output layer, and analyzed the experimental results. As a result of fault injection on the MNIST dataset using a glitch clock, we confirmed that faut injection on into the iteration statements can conduct deterministic misclassification depending on the network parameters.

• Korean Journal of Environmental Agriculture
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• v.24 no.3
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• pp.270-279
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• 2005

It is important to understand and evaluate the environmental impacts of rice cultivation for developing environmentally-friendly agriculture because rice is main crop in Korea and rice cultivation have both functions of water pollution and purification with environmental and cultivation conditions. This paper presents the evaluation of nitrogen impact by rice cultivation on water system. A simple protocol was proposed to assess the potential amount of nitrogen outflow from paddy field and most of parameters affect on the nitrogen outflow from paddy field such as the amount of fertilizer application, water balance, the quality and quantity of irrigation water, soil properties, nitrogen turnover in the soil and cultivation method were considered. To develop the protocol, coefficients for parameters affected nitrogen turnover and outflow were gotten and summarized by comparison and analysis of all possible references related, and by additional experiments at field and laboratory. And potential amount of nitrogen input and output by water in paddy field were estimated with the protocol at the conditions of the nitrogen contents of irrigation water, amount of fertilizer application, and irrigation methods. Where irrigation water was clean, below 1.0 mg $L^{-1}$ of nitrogen concentration, rice cultivation polluted nearby watershed. At the conditions of 2.0 mg $L^{-1}$ of nitrogen concentration, 110 kg $ha^{-1}$ of nitrogen fertilizer application and flooding irrigation, rice cultivation had water pollution function, but it had water purification function with intermittent irrigation. At the conditions of 3.0 mg $L^{-1}$ of nitrogen concentration and 110 kg $ha^{-1}$ of nitrogen fertilizer application, rice cultivation had water purification function, but that had water pollution function with 120 kg $ha^{-1}$ of nitrogen application. Where irrigation water was polluted over 6.0 mg $L^{-1}$ of nitrogen, it was evaluated that rice cultivation had water purifying effect, even though the amount of nitrogen application was 120 kg $ha^{-1}$.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.102-108
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• 2010

The T-S fuzzy model of a ship is made from the nonlinear extension of Nomoto's 2nd-order model as the previous step before designing of the fuzzy type autopilot to consider the design specifications and the economic efficiency. The T-S fuzzy model is considered as a design variable of the heading angular velocity of ship. The linear models will be combined as "IF-THEN" fuzzy rules after get in this one area of the linear model(sub-system) by change of the heading angular velocity of a ship. The dynamic characteristic of a ship with the parameters of linear models and fuzzy membership functions are estimated to match by using the model adjustment technic with input/output data and a RCGA.

• Journal of Navigation and Port Research
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• v.31 no.8
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• pp.697-703
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• 2007

In this paper, we focuses on the development of Takagi-Sugeno (T-S) fuzzy modeling in a nonlinear container crane system. A T-S fuzzy model is characterized by fuzzy "if-then" rules which represent the locally input-output relationship whose consequence part is described by a state space equation as subsystem. The T-S fuzzy model in container cranes first obtains a few number of linear models according to operation conditions and blends these conditions using fuzzy membership functions. Parameters of the membership functions are adjusted by a RCGA to have same dynamic characteristics with nonlinear system of a container crane. Simulations are given to illustrate the performance of T-S fuzzy model.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.3
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• pp.214-221
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• 1998

A new control approach using neural network for the robust position control of a BRUSHLESS direct drive(BLDD) motor is presented. The linear quadratic controller plus feedforward neural network is employed to obtain the robust BLDD motor system approximately linearized using field-orientation method for an AC servo. The neural network is trained in on-line phases and this neural network is composed by a feedforward recall and error back-propagation training. Since the total number of nodes are only eight, this system will be easily realized by the general microprocessor. During the normal operation, the input-output response is sampled and the weighting value is trained by error back-propagation at each sample period to accommodate the possible variations in the parameters or load torque. And the state space analysis is performed to obtain the state feedback gains systematically. In addition, the robustness is also obtained without affecting overall system response.

• The KIPS Transactions:PartB
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• v.13B no.1 s.104
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• pp.15-20
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• 2006

This paper describes research on intelligent game character through performance enhancements of physics engine in computer games. The algorithm that recognizes the physics situation uses momentum back-propagation neural networks. Also, we present an experiment and its results, integration methods that display optimum performance based on the physics situation. In this experiment on integration methods, the Euler method was shown to produce the best results in terms of fps in a simulation environment with collision detection. Simulation with collision detection was shown similar fps for all three methods and the Runge-kutta method was shown the greatest accuracy. In the experiment on physics situation recognition, a physics situation recognition algorithm where the number of input layers (number of physical parameters) and output layers (destruction value for the master car) is fixed has shown the best performance when the number of hidden layers is 3 and the learning count number is 30,000. Since we tested with rigid bodies only, we are currently studying efficient physics situation recognition for soft body objects.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.1
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• pp.70-76
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• 2011

LTE Re1-10 aims at peak. data rates of 1Gbits/s for the downlink and 500 Mbits/s for the uplink, which can be accomplished by not only wide spectrum but also advanced MIMO techniques such as precoded MIMO and cooperative relays. Considering some relays can have more direct signal paths than mobile stations do, LoS components are examined to build more efficient codebooks for Rician channels. The proposed codebooks perform better than the existing LTE codebooks as the criterium of LoS, K-factor increases. Conserving the advantages and max-min chordal distance of the existing LTE codebooks, the proposed ones also maximize the minimum chordal distances between codewords over Rician fading channels. Link-level simulation with LTE system parameters confirm the performance improvements as the value of K increases.