• ETRI Journal
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• v.40 no.1
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• pp.51-60
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• 2018

In Long Term Evolution (LTE) cellular networks, the transmit power control (TPC) mechanism consists of two parts: the open loop (OL) and closed loop. Most cellular networks consider OL/TPC because of its simple implementation and low operation cost. The analysis of OL/TPC parameters is essential for efficient resource management from the cellular operator's viewpoint. In this work, the impact of the OL/TPC parameters is investigated for homogeneous small cells and heterogeneous small-cell/macrocell network environments. A mathematical model is derived to compute the transmit power at the user equipment, the received power at the eNodeB, the interference in the network, and the received signal-to-interference ratio. Using the analytical platform, the effects of the OL/TPC parameters on the system performance in LTE networks are investigated. Numerical results show that, in order to achieve the best performance, it is appropriate to choose ${\alpha}_{small}=1$ and $P_{o-small}=-100dBm$ in a homogenous small-cell network. Further, the selections of ${\alpha}_{small}=1$ and $P_{o-small}=-100dBm$ in the small cells and ${\alpha}_{macro}=0.8$ and $P_{o-macro}=-100dBm$ in the macrocells seem to be suitable for heterogeneous network deployment.

• Journal of Drive and Control
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• v.12 no.3
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• pp.1-10
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• 2015

In this paper, the authors propose a method to easily recognize and reproduce the robot motion made by an operator. This method is targets for applications similar to painting and welding, and it is based on a process of that identifies a family of plants, by control design and by conducting an experimental evaluation. In this study, the models and controllers for all joints of 3DOF robot system are obtained individually. And a robust control system for motion control of the individual joints is designed based on $H_{\infty}$ control framework. An experimental comparison is made between the proposed control method and existing PID control method. And the results indicate that the proposed designing method is more efficient and useful than conventional method.

• International Journal of Computer Science & Network Security
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• v.22 no.7
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• pp.220-228
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• 2022

Image always carry useful information, detecting a text from scene images is imperative. The proposed work's purpose is to recognize scene text image, example boarding image kept on highways. Scene text detection on highways boarding's plays a vital role in road safety measures. At initial stage applying preprocessing techniques to the image is to sharpen and improve the features exist in the image. Likely, morphological operator were applied on images to remove the close gaps exists between objects. Here we proposed a two phase algorithm for extracting and recognizing text from scene images. In phase I text from scenery image is extracted by applying various image preprocessing techniques like blurring, erosion, tophat followed by applying thresholding, morphological gradient and by fixing kernel sizes, then canny edge detector is applied to detect the text contained in the scene images. In phase II text from scenery image recognized using MSER (Maximally Stable Extremal Region) and OCR; Proposed work aimed to detect the text contained in the scenery images from popular dataset repositories SVT, ICDAR 2003, MSRA-TD 500; these images were captured at various illumination and angles. Proposed algorithm produces higher accuracy in minimal execution time compared with state-of-the-art methodologies.

• Journal of Drive and Control
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• v.21 no.1
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• pp.31-37
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• 2024

In this study, to prevent accidents in underground facilities during excavation, we developed a Lv.3 automated control system that can be configured as an electronic control system without changing the existing hydraulic system in a general excavator and utilized digital map information of underground facilities. We aimed to develop a strategy to prevent accidents caused by operator error. To implement this, a real-time excavator bucket end position recognition and control system was developed through angle measurement of the boom, arm, and bucket using an electronic joystick, RTK-GPS, and angle sensors. In addition, excavators are large, machine-based equipment, and it is difficult to control overshoot due to inertia with feedback control using position recognition information of the bucket tip. Therefore, feed-forward control is used to calculate the moving speed of the bucket tip in real-time to determine the target position. We developed a technology that can converge and verified the performance of the developed system through actual vehicle installation and field tests.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.2
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• pp.267-272
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• 2007

This paper proposes a new approach fur the detection of facial feature regions using the characteristic of DCT(discrete cosine transformation) thatconcentrates the energy of an image into lower frequency coefficients. Since the facial features are pertained to relatively high frequency in a face image, the inverse DCT after removing the DCT's coefficients corresponding to the lower frequencies generates the image where the facial feature regions are emphasized. Thus the facial regions can be easily segmented from the inversed image using any differential operator. In the segmented region, facial features can be found using face template. The proposed algorithm has been tested with the image MIT's CBCL DB and the Yale facedatabase B. The experimental results have shown superior performance under the variations of image size and lighting condition.

• The Journal of Advanced Prosthodontics
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• v.10 no.3
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• pp.252-258
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• 2018

PURPOSE. The purpose of this study was to evaluate the repeatability and matching accuracy between two identical intraoral spectrophotometers. MATERIALS AND METHODS. The maxillary right central incisor, canine, and mandibular left central incisor of each of 30 patients were measured using 2 identical intraoral spectrophotometers with different serial numbers (EasyShade V). The color of each shade tab from 3 shade guides (VITA 3D-Master) was also determined with both devices. All measurements were performed by a single operator. Statistical analyses were performed to verify the repeatability, accuracy, and the differences between the devices with paired t-tests, one-way ANOVA, and intra-class correlation coefficients (ICCs) (${\alpha}=.05$). RESULTS. A high level of measurement repeatability (ICC>0.90) among $L^*$, $a^*$, and $b^*$ color components was observed within and between devices (P<.001). Intra-device matching agreement rates were 80.00% and 81.11%, respectively, while inter-device matching agreement rate was 51.85%. ANOVA revealed no significant different color values within each device, while paired t-test provided significant different color values between both devices. The CIEDE2000 color differences between both devices were $2.28{\pm}1.61$ ${\Delta}E_{00}$ for in-vivo readings. Regarding the clinical matching accuracy of both devices, ${\Delta}E_{00}$ values between teeth and matching shade tabs were $3.05{\pm}1.19$ and $2.86{\pm}1.02$, respectively. CONCLUSION. Although two EasyShade V devices with different serial numbers show high repeatability of CIE $L^*$, $a^*$, and $b^*$ measurements, they could provide different color values and shade for the same tooth.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1B
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• pp.51-59
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• 2011

It is the background that the provision of the mobile WiMAX femtocell trial service of a leading mobile telecommunication service operator using small base stations for indoor mobile broadband services and coverage expansion through eliminations of shadow areas in this paper. The paper presents an analysis result of trial subscribers' usage satisfaction for the mobile WiMAX femtocell service and suggests a market approach strategy of a mobile WiMAX femtocell service based on the analysis result. The interesting influence factors are extracted from wide influence factors suggested by existing research literature related with mobile service usage satisfaction and confined to a system quality, a service quality, and an account structure with consideration for attributes of mobile WiMAX femtocell service under exploring its early stages of service market. And then we analyze impacts of the factors to the mobile WiMAX femtocell service usage satisfaction. As a result, a system quality and an account structure have a tendency to provide considerable impacts to subscribers' usage satisfaction for mobile WiMAX femtocell service which is immature in both its technology and market. Therefore a market approach with the preferential consideration of the two factors will be valid.

• Journal of radiological science and technology
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• v.28 no.1
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• pp.19-24
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• 2005

The purpose of this study was to design and implement a useful annotation-based Radiological image retrieval system to accurately determine on education and image information for Radiological technologists. For better retrieval performance based on large image databases, we presented an indexing technique that integrated $B^+-tree$ proposed by Bayer for indexing simple attributes and inverted file structure for text medical keywords acquired from additional description information about Radiological images. In our results, we implemented proposed retrieval system with Delphi under Windows XP environment. End users, Radiological technologists, are able to store simple attributes information such as doctor name, operator name, body parts, disease and so on, additional text-based description information, and Radiological image itself as well as to retrieve wanted results by using simple attributes and text keywords from large image databases by graphic user interface. Consequently proposed system can be used for effective clinical decision on Radiological image, reduction of education time by organizing the knowledge, and well organized education in the clinical fields. In addition, It can be expected to develop as decision support system by constructing web-based integrated imaging system included general image and special contrast image for the future.

• Journal of the Korea Society of Computer and Information
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• v.27 no.9
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• pp.113-120
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• 2022

In this paper, we analyze the feasibility of the IP spoofing attack exploiting null security algorithms in 5G networks based on 3GPP standard specifications. According to 3GPP standard specifications, the initial Registration Request message is not protected by encryption and integrity. The IP spoofing attack exploits the vulnerability that allows a malicious gNB (next generation Node B) to modify the contents of the initial Registration Request message of a victim UE (User Equipment) before forwarding it to AMF (Access and Mobility Management Function). If the attack succeeds, the victim UE is disconnected from the 5G network and a malicious UE gets Internet services, while the 5G operator will charge the victim UE. In this paper, we analyze the feasibility of the IP spoofing attack by analyzing whether each signaling message composing the attack conforms to the 3GPP Rel-17 standard specifications. As a result of the analysis, it is determined that the IP spoofing attack is not feasible in the 5G system implemented according to the 3GPP Rel-17 standard specifications.

• Korean Journal of Agricultural Science
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• v.51 no.3
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• pp.295-305
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• 2024

Due to the environment of irregular soil characteristic for agricultural fields, dynamic characteristic occurs in the tractor cabin during agricultural operations. Operator's fatigue is increased, and operation performance is decreased by these irregular environment conditions. This study was conducted to measure and analyze the dynamic characteristic of a tractor cabin, a major agriculture machinery, during agricultural operations. The specification of tractor used in the study was a 95 kW class tractor. To analyze the dynamic characteristics of the tractor cabin, the main agricultural operations, plow tillage and rotary tillage, were selected. To measure data of dynamic characteristic of the cabin, which continuously changes during operations, an Ellipse Series INS (inertia navigation system) with a built-in IMU (inertia measurement unit) was attached to the center of gravity of the cabin. During field test, the gear stages of plow tillage were B4 (4.3 km·h^-1) and B5 (5.6 km·h^-1), and the gear stages of rotary tillage were A3 (3.3 km·h^-1) and A4 (4.2 km·h^-1), which are the most commonly used. To analyze dynamic characteristic such as roll and pitch during operations according to the gear stages. As a result, the dynamic characteristics of pitch increased more than the dynamic characteristics of roll as the travel speed increased, and the dynamic characteristics of both agricultural operations were in the range of 2 to 5°.