• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.10
• /
• pp.135-143
• /
• 1998

Several equalizers are applied to the DVD-ROM(Digital Versatile Disc-Read Only Memory) system. Because imperfect writing process may cause nonlinear distortion in the reply signal, neural equalizers which have strong nonlinear mapping capability are applied to the system to compensate the nonlinear distortion. Experimental results to verify that the combination of decision-feedback type equalizers and modulation code is formidable are also given. The experimental results shwo that the SNR gain of the neural equalizers over the conventional equalizers becomes much as the nonlinearity in the channel increases. Furthermore, the decision-feedback type equalizers outperform the equalizers which have no decision-feedback in eliminating ISI(Intersymbol Interference) of random data sequence but there is no performance gain of the decision-feedback type equalizers over the equalizers without decision-feedback when these are applied to compensate the ISI of modulation-encoded data sequence.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.10a
• /
• pp.1079-1082
• /
• 2015

In Article 23 of Technical regulations for Telecommunication Line and Facilities, we have criteria of separation distance between telecommunication lines and power lines, and its related exceptional conditions. However, this is a conflicts condition with Article 32 that provides the type of indoor telecommunication cables such as twisted-pair cables and optical fiber cables. Also, it is frequently raised that exceptional condition related the PoE cables with up to 15.4W is improved to accept PoE cables with up to 30W. In this paper, we have proposed improvement plans of Technical regulations for separation distance between telecommunication lines and power lines by analyzing the variety of standard specifications at home and abroad.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2019.10a
• /
• pp.176-179
• /
• 2019

최근 세계적으로 한국에 대한 인식이 좋아짐으로써 한국으로 유학이나 여행을 오는 외국인이 많아지고 있다. 외국은 다양한 문화와 언어를 가지고 있고 그 외국의 문화와 언어에 익숙하지 않은 많은 식당에서 그들은 식사함에 어려움을 겪고 있다. 우리 학교의 경우에서도 마찬가지로 유학 와 있는 한국어가 서툰 학생들이 한국에서 가장 불편한 일 중 하나가 식당에서 음식을 시키는 것이라고 할 정도로 식사가 제한되어 있다. 이를 해결하기 위해 본 논문에서는 QR 코드를 메뉴판에 부착하여 그 QR 코드를 찍기만 하면 바로 원하는 언어를 선택할 수 있고, 그들의 언어로 음식에 대한 설명이 나타나는 시스템을 제안하고 개발하였다. 제안한 시스템은 종교에 따라 먹지 못하거나, 식습관에 따라 먹지 않는 음식이 있는 외국인들 역시 전자 메뉴판을 이용함으로 어려움을 해결 할 수 있다. 제안한 시스템은 그들 주변에 어떤 식당이 있고 어떤 음식이 있는지 쉽게 알 수 있고 그 어플을 사용하는 사람들과 소통할 수 있는 어플리케이션을 제작함으로써 유학생뿐만 아닌 일반 관광객들을 대상으로도 적극적으로 활용 할 수 있을 것으로 기대가 된다.

• Journal of Korean Society for Quality Management
• /
• v.49 no.4
• /
• pp.483-503
• /
• 2021

Purpose: The purpose of this study is to investigate the service quality factors in terms of customer trust, satisfaction and loyalty of the Korean telecommunication companies(SKT, KT, LG U+). Specifically, this study presents new business strategies of the each company, thereby pursuing the innovation for mature stage. Methods: To analyze the telecommunication service quality factors that contribute to customer trust, satisfaction and loyalty, this study conducted a survey targeting customers of each company. Using the data collected, the research model was built, and empirical analysis was performed through statistical processing to verify the model. Furthermore, the clarification of each hypothesis were held including the comparison analysis of each company data. Results: The results of this study are as follows; (1) When it comes to total dataset, all quality factors including trust, satisfaction and loyalty showed significant relationship, accepting every hypothesis. (2) However, for SKT and LG U+, empathy showed no significant impact on trust while the others showed significant effect. (3) Finally for KT, all service quality factors such as responsiveness, empathy, security, and customer enablement had a significant effect on trust. Conclusion: As the development of platform industry are intensified, telecommunication companies are required to manage service quality factors thoroughly, especially focusing on customer privacy and security.

• Journal of Broadcast Engineering
• /
• v.25 no.6
• /
• pp.836-844
• /
• 2020

A very large number of pixels is required to generate a computer generated hologram (CGH) with a large-size and wide viewing angle equivalent to that of an analog hologram, which incurs a very large amount of computation. For this reason, a high-performance computing device and long computation time were required to generate high-definition CGH. To solve these problems, in this paper, we propose a technique for generating high-definition CGH by arraying the pre-calculated low-definition CGH and multiplying the appropriately-shifted concave lens function. Using the proposed technique, 0.1 Gigapixel CGH recorded by the point cloud method can be used to calculate 2.5 Gigapixels CGH at a very high speed, and the recorded hologram image was successfully reconstructed through the experiment.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2020.11a
• /
• pp.556-559
• /
• 2020

최근 태풍, 지진, 산불, 산사태, 전쟁 등 다양한 재난 상황으로 인한 인명피해와 자금 손실이 꾸준히 발생하고 있고 현재 이를 예방하고 복구하기 위해 많은 인력과 자금이 소요되고 있는 실정이다. 이러한 여러 재난 상황을 미리 감시하고 재난 발생의 빠른 인지 및 대처를 위해 본 논문에서는 인공지능 기반의 재난 드론 시스템을 설계 및 개발하였다. 본 연구에서는 사람이 감시하기 힘든 지역에 여러 대의 재난 드론을 이용하며 딥러닝 기반의 최단 경로 알고리즘을 적용해 각각의 드론이 최적의 경로로 효율적 탐색을 실시한다. 또한 드론의 근본적 문제인 배터리 용량 부족에 대한 문제점을 해결하기 위해 Ant Colony Optimization (ACO) 기술을 이용하여 각 드론의 최적 경로를 결정하게 된다. 제안한 시스템 구현을 위해 여러 재난 상황 중 산불 상황에 적용하였으며 전송된 데이터를 기반으로 산불지도를 만들고, 빔프로젝터를 탑재한 드론이 출동한 소방관에게 산불지도를 시각적으로 보여주었다. 제안한 시스템에서는 여러 대의 드론이 최적 경로 탐색 및 객체인식을 동시에 수행함으로써 빠른 시간 내에 재난 상황을 인지할 수 있다. 본 연구를 바탕으로 재난 드론 인프라를 구축하고 조난자 탐색(바다, 산, 밀림), 드론을 이용한 자체적인 화재진압, 방범 드론 등에 활용할 수 있다.

• Journal of the Optical Society of Korea
• /
• v.8 no.2
• /
• pp.90-95
• /
• 2004

The structure of Ti:LiNbO$_3$optical waveguide with a mode size far different from that of single mode optical fiber has been optimized by tapering the waveguide ends. This work was focused on determining the optimized sets of parameters for the fabrication of low-loss Ti indiffused optical waveguides in LiNbO$_3$. Numerical and analytical modeling were applied to simulate the guiding quality and to determine the mode sizes. Based on these modeling results, new waveguide structures with tapered ends have been defined, fabricated and characterized in the respect of the coupling of fiber to Ti-indiffused LiNbO$_3$waveguide.

• ETRI Journal
• /
• v.26 no.6
• /
• pp.605-614
• /
• 2004

In this paper, we investigate array calibration algorithms to derive a further improved version for correcting antenna array errors and RF transceiver errors in CDMA smart antenna systems. The structure of a multi-channel RF transceiver with a digital calibration apparatus and its calibration techniques are presented, where we propose a new RF receiver calibration scheme to minimize interference of the calibration signal on the user signals. The calibration signal is injected into a multi-channel receiver through a calibration signal injector whose array response vector is controlled in order to have a low correlation with the antenna response vector of the receive signals. We suggest a model-based antenna array calibration to remove the antenna array errors including mutual coupling errors or to predict the element patterns from the array manifold measured at a small number of angles. Computer simulations and experiment results are shown to verify the calibration algorithms.

• ETRI Journal
• /
• v.29 no.3
• /
• pp.305-310
• /
• 2007

If a virtual object in a virtual environment represented by a stereo vision system could be touched by a user with some tactile feeling on his/her fingertip, the sense of reality would be heightened. To create a visual impression as if the user were directly pointing to a desired point on a virtual object with his/her own finger, we need to align virtual space coordinates and physical space coordinates. Also, if there is no tactile feeling when the user touches a virtual object, the virtual object would seem to be a ghost. Therefore, a haptic interface device is required to give some tactile sensation to the user. We have constructed such a human-computer interaction system in the form of a simple virtual reality game using a stereo vision system, a vibro-tactile device module, and two position/orientation sensors.

• ETRI Journal
• /
• v.29 no.2
• /
• pp.231-233
• /
• 2007

One of the drawbacks in an OFDM system is the high peak-to-average power ratio (PAPR). Among a number of techniques to reduce the high PAPR, simple amplitude predistortion (SAP), a form of active constellation extension, has been proposed to effectively achieve the desired PAPR. In this letter, a novel scheme, simple amplitude and phase predistortion (SAPP), is proposed. In SAP the carriers' amplitude is utilized to combat the peak signal. Each amplitude is amplified according to its degree of contribution as a metric. In addition to amplitude, SAPP also utilizes the phase. Simulation results indicate that the proposed scheme provides better PAPR reduction than SAP.