• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1118-1130
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• 1999

In this paper, error performance of DS/FH CDMA system has been analyzed in a radio channel which is characterized by near-far problem and multi-path fading. The DS/FH CDMA system adopts Maximum Ratio Combining(MRC) diversity and BCH(Bose-Chau dhuri-Hocquenghem) coding techniques to enhance system performance. Using the derived error probability equation, the error performance of DS/FH CDMA system has been evaluated and shown in figures to discuss as a function of PN code length(N), hopping rate(q), number of diversity branch(M), coding rate($\gamma$) and bit energy per noise power ratio ${E_b/N_o}$. The results show that DS/FH system is more effective to restrain the affection of near-far problem and multi-path fading than DS system. And there is a substantial enhancement in performance by employing an MRC diversity or BCH coding techniques. Consequently, we expected that proposed system structure is reliable to the voice communication system in near-far problem and multi-path fading channel.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.1
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• pp.124-133
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• 2021

Smart factory is a future factory that collects, analyzes, and monitors various data in real time by attaching sensors to equipment in the factory. In a smart factory, it is very important to inquire and generate the status and history of equipment in real time, and the emergence of various smart devices enables this to be performed more efficiently. This paper proposes a multi device-based system that can create, search, and delete equipment status and history in real time. The proposed system uses the Android system and the smart glass system at the same time in consideration of the special environment of the factory. The smart glass system uses a QR code for equipment recognition and provides a more efficient work environment by using a voice recognition function. We designed a system structure for real time equipment monitoring based on multi devices, and we show practicality by implementing and Android system, a smart glass system, and a web application server.

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.735-745
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• 2023

The purpose of this study is to examine how the control of an agent according to a driver's social status affects user experience factors in a multi-user environment of self-driving vehicles. We conducted a user study where participants viewed four scenarios (route changing/parking x accepting/declining a fellow passenger's command) and answered a survey, followed by a post-hoc interview. Results showed that either the routing scenario or accepting a passenger's command scenario had higher usefulness (convenience, effectiveness, efficiency) than their counterparts. Regardless of the car owner's social status, participants rated AI agents more positively when they met their goals effectively. They also stressed that vehicle owners should always be in control of their agents. This study can provide guidelines for designing future autonomous driving scenarios where an agent interacts with a driver, and passengers.

• The Journal of the Acoustical Society of Korea
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• v.28 no.5
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• pp.432-440
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• 2009

Recently, the necessity of underwater acoustic communication and demand for transmitting and receiving various data such as voice or high resolution image data are increasing as well. The performance of underwater acoustic communication system is influenced by underwater channel characteristic. Especially, a delay spread caused by reverberation and multi-path induces the ISI (Inter-Symbol-Interference) and reduces the communication performance. In this paper, we study the OFDM (Orthogonal Frequency Division Multiplexing) technique for robust the delay spread in underwater channel. We also use the clipping method to overcome the performance degradation in high PAPR (Peak-to-Average Power Ratio). We confirm the performances of underwater communication system by the underwater channel model simulation model and experiment in small water tank. As a result, the multi-carrier modulation with clipping method presented low BER and the previous single carrier modulation had high BER.

• The Journal of the Korea Contents Association
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• v.12 no.4
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• pp.60-68
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• 2012

In recent years, the requirements on the high quality environment monitoring by using the sensor nodes which can handle the multimedia data in WSN have been increased. However, because the volume of multimedia data is tremendous, the limited bandwidth of a wireless channel may incur the bottleneck of a system. To solve such a problem, most of the existing distributed multi-path routing protocols based on multimedia data just focused on overcoming the limited bandwidth in order to enhance the energy efficiency and the transmission rate. However, because the existing methods can not apply a key-based technique to encrypt the multimedia data, they are very weak for the security. In this paper, we propose a secure disjointed multipath routing scheme for multimedia data transmission. Since our proposed scheme divides multimedia data(eg. image) into pixels and sends them through disjointed multipath routing, it can provide security to the whole network without using the key-based method. Our experimental results show that our proposed scheme reduces about 10% the amount of the energy consumption and about 65% the amount of the missed data packets caused by malicious nodes over the existing methods on average.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.11B
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• pp.1864-1871
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• 2000

본 논문에서는 차세대 무선 통신 시스템에 적용이 가능한 새로운 FEC(Forward Error Correction) 부호화 방법으로 MLC(Multi-Level Convolutional) 부호화 방식을 제안한다. 차세대 무선통신서비스는 음성, 데이터, 영상 등 많은 종류의 서비스를 함으로써 데이터의 처리속도가 빠른 시스템이 요구된다. 데이터 처리시간을 단축시키기 위한 방법으로 다중 레벨을 이용하여 부호어를 만들어 내는 방식의 부호화 시스템을 설계하였다. MLC는 부호 처리시간을 단축시킬 뿐만 아니라 다양한 알고리즘을 이용해 부호어를 만들어 낼 수 있다는 특징을 가지게 된다. 모의실험은 MLC 코드의 두 가지 방법, Modulo- operation 방식과 Galois Field-Operation 방식을 이용하여 수행하였다. 또한 모의실험을 통하여 (s=2, T=2)인 경우가 MLC 부호기의 최적 연결다항식임을 알았다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06c
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• pp.80-85
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• 1994

자동통역에서의 대화체 기계번역은 일반적인 문어체 문장 번여고가는 다른 몇가지 특징을 고려하여야 한다. 첫째, 자동통역에서의 기계번역은 음성인식의 결과를 번역하는 부분으로, 하나의 문장이 아닌 다중 입력을 받아 이 중 가장 올바른 문장을 번역하여야 한다. 둘째, 대화체 문장에서는 일반적으로 생략을 포함하는 단편적인 발화나 대용어의 사용빈도가 많다. 그러나, 이러한 현상은 언어마다 다소 다르게 사용되기 때문에 이들에 대한 올바른 해석을 한 후 번역하는 것이 필요하다. 대화체 기계번역이 이러한 문제점들을 해결하기 위해서는 문맥정보를 필요로 한다. 대화는 상호간 밀접한 관련성을 가지고 진행되기 때문이다. 이에 본 논문에서는 담화분석을 통해 올바르게 구축하고, 이 정보를 이용하여 앞에서 언급한 문제점들을 해결하기 위한 방법론에 대해 논하고자 한다.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1219-1222
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• 1998

This paper analyzes the dynamic spars algebraic codebook used to model a residual signal and proposes a new algebraic codebook structure as well as a searching process with improved performance. The proposed algorithm improves the disadvantage of algebraic codebook without increased computation. First, this paper makes it possibel to select various pulse amplitudes differently from the conventional method which looks up the sign bit simply. In addition, two pulses are made to be selected on the same track. For speech quality on the telephone line 5.6kbps speech coder using the proposed algorithm was equivalent to the 6.3kbps MP-MLQ in the viewpoint of subjective speech quality. However, speech degradation was caused a little compared to the MP-MLQ where MNRU 1=15dB.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.04a
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• pp.367-371
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• 2007

최근 여러 지역에서 발생되는 지하철 참사 및 대형화재 또는 지하철 역사, 대형 지하상가, 백화점, 지하공간, 대형쇼핑센터, 숙박업소, 공공건물등 대형 다중이용시설 등에서 발생될 수 있는 예측 불가능한 인재, 천재지변에 안전하게 대피하기 위한 수단으로 비상등 및 여러 감지기들이 소방법 개정으로 의무설치 하고 있다. 비상등 및 감지기들은 비상시 위험 감지 및 경고 전파를 위해 사용되는데 방음벽이나 격벽, 경고 거리의 제한으로 인해 경고 전달의 어려움이 있다. 본 논문에서는 무선 데이터 전송기능 및 경고등, 음성전파 기능을 갖는 무선 지능형 화재 감지/경고시스템을 설계하고자 한다.

• The Journal of the Acoustical Society of Korea
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• v.18 no.4
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• pp.47-52
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• 1999

In this paper, we proposed a new approach to weight each feature parameter by considering the dispersion of feature parameters and its degree of contribution to recognition rate. We determined the total distribution factor that is proportional to recognition rate of each feature parameter and the dispersion factor according to the dispersion of each feature parameter. Then. we determined state-dependent weighting using the total distribution factor and dispersion factor. To verify the validity of the proposed approach, recognition experiments were performed using the PLU(Phoneme-Like Unit)-based HMM. Experimental results showed the improvement of 7.7% at the recognition rate using the proposed method.