• 드라이브 ㆍ 컨트롤
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• 제12권3호
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• pp.11-17
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• 2015

An intelligent deburring control (IDC) device is used to control the constant force for a deburring tool mounted on the end-effector of a robotic arm. This device maintains a constant contact force between the deburring tool and the workpiece in order to provide a good deburring performance. In this paper, we build a mathematical model in Matlab/Simulink to estimate the force control mechanism of the pneumatic system for the IDC device. The Simulink blocks are built for each separate part and are linked into an integrated simulation system. Such a model also relies on the effects of the flow rate through the valve, air compressibility in the cylinder, and time delay in the pressure valve. The results of the simulation are compared to a simple experiment in which convenient math modeling is performed. These results are then used to optimize the mechanical design and to develop a force control algorithm for the pneumatic cylinder.

• International Journal of Computer Science & Network Security
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• 제21권3호
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• pp.229-234
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• 2021

The explosive growth of video-based services is considered as the dominant contributor to Internet traffic. Hence it is very important for video service providers to meet the quality expectations of end-users. In the past, the Quality of Service (QoS) was the key performance of networks but it considers only the network performances (e.g., bandwidth, delay, packet loss rate) which fail to give an indication of the satisfaction of users. Therefore, Quality of Experience (QoE) may allow content servers to be smarter and more efficient. This work is motivated by the inherent relationship between the QoE and the QoS. We present a no-reference (NR) prediction model based on Deep Neural Network (DNN) to predict video QoE. The DNN-based model shows a high correlation between the objective QoE measurement and QoE prediction. The performance of the proposed model was also evaluated and compared with other types of neural network architectures, and three known machine learning methodologies, the performance comparison shows that the proposed model appears as a promising way to solve the problems.

• 로봇학회논문지
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• 제16권2호
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• pp.147-154
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• 2021

One of the most challenging issues when robots interact with the environment is to establish contact quickly and avoid high impact force at the same time. The proposed method implements the passive suspension system using the redundancy of the torque-controlled robot. Instead of utilizing the actual mechanical compliance, the distal joints near the end-effector are controlled to act as a virtual spring-damper system with low feedback gains. The proximal joints are precisely controlled to push the mid-link, which is defined as the boundary link between the proximal and distal joints, towards the environment with high feedback gains. Compared to the active compliance methods, the contact force measurements or estimates are not required for contact establishment and the control time delay problems do not occur correspondingly. The proposed method was applied to the landing foot control of the 12-DoF biped robot DYROS-RED in the simulations. In the results, the impact force during landing was significantly reduced at the same collision speed.

• 산업경영시스템학회지
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• 제46권4호
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• pp.321-330
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• 2023

The Korean military has sought to build an all-round military force against the national and international security environment and future asymmetric threats as well as the military threats it faces. However, while raising the need for timely electrification, there are few cases of quantitatively evaluating the loss when electrification is delayed, making it difficult for our military to provide a logical basis to support the importance of the electrification period. Therefore, through this study, we tried to analyze the index of loss cost that can support the need for timely electrification with logical and quantitative data and present it as a logical basis. To this end, the loss cost was calculated in terms of combat efficiency, equipment utilization rate, and maintenance requirements, which can be quantitatively calculated based on "combat readiness," a general impact on the military in case of delayed timely electrification.

• 정보처리학회논문지A
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• 제11A권3호
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• pp.129-138
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• 2004

Even though the Internet applications such as e-mail and FTP are widely used, fax is still an important media for data communications till today. Many researches on security over the Internet data communication have been done over the years, on the other hand not many researches have been dedicated to the fax security issue which is as important as the Internet. In this paper, we describe the development of hardware and software of the embedded security fax server which increases the security in supporting existing fax. The developed system is designed and implemented to maintain security while minimizing the delay due to encryptionㆍdecryption. Since there's international or domestic tryptographic standard and each nation have their policy to restrict the use of cryptographic system, we adopt domestic standard cryptographic protocol admitted in Korea. And the system supports two modes： Security mode and Non-Security mode that user can choose from. The system can be applied directly which is the requirements of users at company ,End the government. We verify the performance and functioning of the system in various real environment.

• 융복합기술연구소 논문집
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• 제9권1호
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• pp.13-19
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• 2019

The purpose of this study is to suggest a new method to determine a combustion phase (start of combustion and end of combustion) using a combustion pressure data. Unlike previous research method that used heat release amount, the difference between the combustion pressure measured in the combustion chamber and the motoring pressure was used to determine the combustion phase. This research was conducted using a single-cylinder diesel engine with a compression ratio of 17.7. The test was conducted under various injection timing. The newly proposed method showed high accuracy in combustion mode with early injection, as well as the conventional combustion mode. It is expected that this method will be used to study new combustion strategies such as HCCI (homogeneous charge compression ignition) and RCCI (reactivity controlled compression ignition) that are applying early injection strategies as well as existing combustion modes.

• International Journal of Advanced Culture Technology
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• 제4권3호
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• pp.13-19
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• 2016

The growth of mobile devices in Internet of Things (IoT) leads to a number of remote and controlling system related IoT applications. For instance, home automation controlling system uses client system such web apps on smartphone or web service to access the home server by sending control commands. The home server receives the command, then controls for instance the light system. The web service gateway responsible for handling clients' requests attests an internet latency when an increasing number of end users requests submit toward it. Therefore, this web service gateway fails to detect several commands, slows down predefined actions which should be performed without human intervention. In this paper, we investigate the performance of a web server-side platgorm based event-driven, non-blocking approach called Node.js against traditional thread-based server side approach to handle a large number of client requests simultaneously for remote and controlling system in IoT remote monitoring applications. The Node.JS is 40% faster than the traditional web server side features thread-based approach. The use of Node.js server-side handles a large number of clients' requests, then therefore, reduces delay in performing predefined actions automatically in IoT environment.

• 한국컴퓨터정보학회논문지
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• 제4권4호
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• pp.101-112
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• 1999

NPEG은 ISO 산하의 표준화 위원회에서 동영상 압축 기술의 필요에 의해 표준화된 동영상 압축 기술로 통신상에서 더 높은 비트율의 고화질 동화상 실현의 요구에 의해 1995년에 MPEG 2가 개발되었다. 본 논문에서는 VBR MPEG의 코드화된 완전한 동화상 통신을 위해 비선형 시계열 방식으로 효율적이고도 정확한 TAR모델 설계 알고리즘을 제안하며 실질적인 동영상 비디오 추적에 대한 통계적 특성을 보여주는 시뮬레이션 결과를 제시하고자 한다.

• 한국정보통신학회논문지
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• 제14권2호
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• pp.329-334
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• 2010

무선 이동 통신망의 발전으로 단말의 현재 위치를 기반으로 한 다양한 위치 기반 서비스가 출현하고 있다. 와이브로 망과 같은 모바일 와이맥스 망에서도 LBS (Location Based Service) 서비스의 제공은 망 기술의 경쟁력을 제고하기 위해 매우 중요하다. 이를 위해, 와이맥스 포럼은 최근 LBS 서비스 제공을 위한 망 구조 및 프로토콜을 네트워크 워킹 그룹의 release 1.5 문서에 포함하여 표준화 하였다. 그동안 와이브로 망에서 측위에 관한 많은 연구가 있어 왔지만, 최근 확립된 와이맥스 포럼의 LBS 표준을 고려하여 표준에 적합한 위치 결정 방식에 관한 연구는 아직 없다. 본 논문에서는 와이맥스 포럼의 LBS 표준을 고려하여, 이에 부합하는 위치 결정 방식을 제안한다. 이 방식은, RTD (Round Trip Delay) 방식을 결합하여 기존 TDOA 방식을 개선하였다.

• Bulletin of the Korean Chemical Society
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• 제15권8호
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• pp.663-669
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• 1994

Decay kinetics of Ga(5s), Ga(5p) and Ga(4d) atoms in Ar were studied by laser induced fluorescence technique. Theground state gallium atoms in the gas phase were generated by pulsed dc discharge of trimethyl gallium and argon mixtures. Both pulsed discharge and YAG-DYE laser system were controlled by a dual channel pulse generator and the delay time between the end of discharge and laser pulses was set 3.0-6.0 ms. The Ga(5s) and Ga(4d) atoms were generated by single photon excitation from the ground state Ga atoms and radiative lifetimes as well as the total quenching rate constants in Ar were obtained from the pressure dependence of the fluorescence decay rates. The Ga(5p) atoms were populated by a two-photon excitation method and the cascade fluorescence from Ga(5s) atoms were analyzed to extract quenching rate constant of Ga(5p) atoms by Ar in addition to radiative lifetimes of Ga(5p) state. The magnitudes of the quenching rate constants by Ar for the low-lying excited states of Ga atoms are 1.6-3$ {\times}10^{-11}cm^3$ molecul$e^{-1}s^{-1}$, which are much larger than those for alkali, alkaline earth and Group 12 metals. Based on the measured rate constants, kinetic simulations were done to assign state-to-state rate constants.