• The Journal of Natural Sciences
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• v.8 no.2
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• pp.5-7
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• 1996

Let {X,$X_n$,n$\geq$1} be i.i.d. random variables with mean zero and {$a_ni$, 1$\leq$i$\leq$n,n$\geq$1} a triangular array of constants. In this paper we give sufficient conditions on X and {$a_ni$} such that $sum_{i=1}^n$$a_{ni}$$X_i$ converges to zero almostly surely.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.1
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• pp.67-73
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• 2002

This paper presents a new design method of optimal continuous deadbeat controller by using second-order smoothing elements. The continuous deadbeat controller is made of a serial integral compensator and a local feedback compensator introduced into the state feedback loop. The decision method of the damping factor and the natural angular frequency of the smoothing element is described. A numerical example is given to show how well input-output characteristics are improved. Especially according to the variable input and disturbance, corresponding CDBC design method is suggested. By computer simulations, control inputs and system outputs are shown to have desirable property such as smoothness.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.2
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• pp.125-132
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• 2017

The slope of the road in the forest area has a characteristic of steep slope, so natural disasters such as slope collapse occur. The slope displacement observation technique according to landslide is being studied as a method to observe a wide area and a method to observe a small area. This is a study on high-precision digital map generation using ground LiDAR. It is possible to create a high - precision digital map by minimizing the US side using the 3D LiDAR in the steep slope area where the GPS and Total Station measurement are difficult in the maintenance of the danger slope area. It is difficult to objectively evaluate whether the contour lines generated by LiDAR are correct and it is considered necessary to construct a test bed for this purpose. Based on this study, if terrain changes such as landslides occur in the future, it will be useful for measuring slope displacement.

• Journal of Advanced Information Technology and Convergence
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• v.10 no.2
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• pp.139-151
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• 2020

Entity name recognition is a part of information extraction that extracts entity names from documents and classifies the types of extracted entity names. Entity name recognition technologies are widely used in natural language processing, such as information retrieval, machine translation, and query response systems. Various deep learning-based models exist to improve entity name recognition performance, but studies that compared and analyzed these models on Korean data are insufficient. In this paper, we compare and analyze the performance of CRF, LSTM-CRF, BiLSTM-CRF, and BERT, which are actively used to identify entity names using Korean data. Also, we compare and evaluate whether embedding models, which are variously used in recent natural language processing tasks, can affect the entity name recognition model's performance improvement. As a result of experiments on patent data and Korean corpus, it was confirmed that the BiLSTM-CRF using FastText method showed the highest performance.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.5
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• pp.1175-1180
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• 2024

The fuel supply pipe connected to the hydrogen fueled vehicle hydrogen tank is very complicated. Therefore, the fixed portion of the pipe should be determined according to the external vibration. In particular, in order to avoid the resonance frequency range of the hydrogen fueled vehicle, it is necessary to examine the vibration characteristics of the fuel supply pipe and the stress concentration generation part for each frequency. Therefore, the purpose of this study is to understand the resonance potential for the natural frequency of the fuel supply pipe for hydrogen fueled vehicles and the excitation force(vibration of the motor etc.) applied to the external excitation frequency range(1-40Hz). Vibration characteristics were analyzed using the finite element method(FEM) to secure basic data for future seismic vibration tests of fuel supply pipes and to evaluate the safety of fuel supply pipe system.

• Journal of Advanced Information Technology and Convergence
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• v.8 no.2
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• pp.89-99
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• 2018

Due to global warming, various natural disasters such as floods and droughts are increasing. If we can detect the possibility of natural disasters in advance, we can prevent massive damages caused by natural disasters. Recent advances in visual sensor technologies have enabled remote monitoring of a variety of natural environments, including lakes, rivers, and shores. In this paper, we propose a method to segment an image obtained from video sensor networks into regions in order to monitor the environment effectively. In the proposed method, we first partition the image into superpixels and model the connections between superpixels as a graph. Then, initial seeds for each region are set by using the prior information, and the initial seeds are expanded to form regions using agglomerative clustering. Experimental results show that the proposed method extracts the regions from natural environment images easily and accurately.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.2
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• pp.89-96
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• 2007

For the environment protection, carbon dioxide as a natural refrigerant has been studied to use in an automotive air conditioning system. Hence, a numerical model has been developed to describe the evaporation phenomena of carbon dioxide flowing through very small diameter tubes. The two dimensional low-Reynolds $k-{\varepsilon}$ model was used to predict the flow phenomena of carbon dioxide in the two phase during its evaporation. Furthermore, the results obtained from the model were compared with the experiments for the validation. The heat transfer coefficient is lower, as the tube inner diameter becomes smaller. However, the amount of heat absorbed by a unit mass of carbon dioxide is greater due to more surface area. Therefore, the small diameter tube has advantage in terms of compact design of evaporator. When the inlet condition of pressure and temperature is low, the heat transfer coefficient is slightly high at the same size of tube because of the thermal properties of carbon dioxide.

• Applied Science and Convergence Technology
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• v.26 no.4
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• pp.86-90
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• 2017

We have reported structural and optical properties of self-assembled InAs/GaAs quantum dot (QD) grown by molecular beam epitaxy with different arsenic to indium flux ratios (V/III ratios). By increasing the V/III ratio from 9 to 160, average diameter and height of the InAs QDs decreased, but areal density of them increased. The InAs QDs grown under V/III ratio of 30 had a highest-aspect-ratio of 0.134 among them grown with other conditions. Optical property of the InAs QD was investigated by the temperature-dependent photoluminescence (PL) and integrated PL. From the temperature dependence PL measurements of InAs QDs, the activation energies of $E_{a1}$ and $E_{a2}$ for the InAs QDs were obtained $48{\pm}3meV$ and $229{\pm}23meV$, respectively. It was considered that the values of $E_{a1}$ and $E_{a2}$ are corresponded to the energy difference between ground-state and first excited state, and the energy difference between ground-state and wetting layer, respectively.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.4_2
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• pp.443-451
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• 2021

It is essential to examine and analyze the power output and load responses together using real-world turbulent wind speeds. In this paper, the power controller and the drive train damper are simultaneously considered using the NREL 5MW wind turbine model, and the damage equivalent load(DEL) of the low speed shaft torque and power output responses according to the natural frequency of the second order low pass filter are simultaneously investigated. Numerical testing is carried out above rated wind speed using commercially available Bladed software. From the viewpoints of DEL reduction of the drive train shaft torque and power output responses, it is shown that the natural frequency of the low pass filter is appropriately about 6 to 10rad/s. And the reduction ratio of the DEL of the low-speed shaft torque decreases as the wind speed becomes higher, and it is confirmed that the reduction ratio is limited to about 20% at high wind speeds.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.3
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• pp.222-232
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• 2013

In recent years, 'technological fusion or convergence' has drawn a lot of attention of innovation researchers and governmental policy makers as the driving force of technological innovation and industrial growth. There are, however, few studies on the analysis of longitudinal trends of technological convergence and its comparison between global and national level. In this study, with the citation data of about 18 million articles, we analyzed 1) the growth of representative convergence research areas, 2) the convergence of citing patterns between research fields, and 3) the changing trend of diversity index of all research fields. We conclude that technological convergence in korea shows the relatively strong orientation to the combination of neighboring fields than that of heterogenous fields in comparison to global trend. In particular, the relatively weak activity of cognitive science and the low level of mutual exchange between arts/humanities/social sciences and natural/engineering sciences in Korea are emphasized.