• Proceedings of the KSR Conference
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• 2006.05b
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• pp.786-792
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• 2006

• Proceedings of the KIEE Conference
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• 1982.07a
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• pp.70-72
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• 1982

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.4
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• pp.148-156
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• 2009

This paper presents a new image rejection algorithm based on the analysis of the distortion of a single-frequency continuous-wave (CW) signal due to the I/Q mismatch. Existing methods estimated the gain mismatch and phase mismatch on RF receivers and compensated them However, this paper shows that the circular trajectory of a single-frequency CW signal is distorted elliptic-type trajectory due to the I/Q mismatch. Utilizing the analysis, we propose a I/Q mismatch compensation method. It has two processing steps. In the first processing step, the generated signal is rotated to align the major axis of the elliptic-type trajectory diagram with the x-axis. In the second processing step, the Q-channel signal in the regenerated signal is scaled to align the regenerated signal with the transmitted single-frequency CW signal. Simulation results show that a receiver using the proposed image rejection algorithm can achieve an image rejection ratio of more than 70dB. And, simulation results show that the bit error rate performances of receivers using the proposed image rejection algorithm are almost the same as those of conventional coherent demodulators, even in fading channels.

• 한국벤처창업학회:학술대회논문집
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• 2021.11a
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• pp.135-142
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• 2021

20년 3월부터 본격화된 코로나 팬데믹은 전세계경제에 큰 충격으로 불확실성은 더욱 커져 경제생태계 대변혁의 시대를 맞이하고 있는 가운데 고령 인구의 증가, 생산인구의 감소와 더불어 20년 12월 기준 직장의 폐업과 정리해고, 경영부진 등 비자발적인 일자리를 떠난 사람이 19년 대비 48.9%(2020 통계청) 증가, 직장인의 퇴직 평균연령도 51.7세로 직장인 의지와 관계없이 조기 은퇴가 불가피한 상황이다. 한편 직장 근로자 10명중 8명은 창업할 의지가 있는 것으로 나타나 이제는 직장인의 창업은 선택이 아닌 필수로 인식하고 있다. 본 연구의 목적은 직장인의 기업가정신과 지속학습, 보상만족, 고용가능성이 창업의지와 어떠한 상관관계를 가지고 있는가를 조사하고 혁신행동이 매개역할을 하는지에 대해 분석하는데 있다. 본 연구에서는 직장 재직자의 기업가정신과 직장생활 과정에서 지속학습, 보상만족, 고용가능성이 창업의지에 미치는 영향에 관한 연구를 혁신행동의 매개효과를 중심으로 진행하였다. 따라서 본 연구에서는 재직자의 기업가정신과 지속학습, 보상만족, 고용가능성이 혁신활동을 증가시키고, 증가된 혁신활동이 창업의지에 영향을 미칠 것이라는 인과적 경로를 검증하고자 한다. With Corona의 불확실한 경제여건에서 조직은 생존을 위한 끊임없는 변화를 추구함에 따른 재직자의 고용불안은 가중될 것이며, 100세 시대를 준비해야 하기에 창업은 필수적 상황으로 창업의지를 종속변수로 설정하여 본 연구를 진행하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.135-138
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• 2002

본 논문은 반향경로의 순지연 시간 추정 및 보상을 이용한 네트워크 반향 제거기의 실시간 구현에 관한 연구이다. VoIP 게이트웨이와 연결된 복잡한 교환기망(PSTN)에서 발생되는 건 반향은 통화품질의 저하를 초래한다. 긴 순지연 시간을 포함하는 반향을 실시간 구현에 적합한 연산량으로 제거하기 위해, 간축 영역에서 반향 경로를 추정하여 순지연 시간을 추정후 보상하는 반향제거기를 구현하였다. 순지연 시간의 안정적인 추정을 위해 문턱치 보다 큰 유효 계수를 이용하여 순지연 시간을 추정하는 기법을 제안하였으며, 실시간 구현시 순간 최대 연산량을 줄이기 위해 추정된 반향 경로를 분할하여 순지연 시간을 추정하는 기법을 제안하였다. 제안된 시스템을 Texas Instruments사의 16비트 고정소수점 DSP TMS320C5409를 사용하여 구현하였고, 시뮬레이터를 통하여 성능을 검증하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.42-49
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• 2016

In this paper, we design and fabricate an instantaneous frequency measurement receiver with a frequency resolution of 125 MHz which detects and measures continuous signals in 4~6 GHz using path difference of delay lines. The receiver has a 4-bit configuration and consists of power dividers, delay lines, power combiners, power detectors, voltage comparator circuits and so on. The accuracy of the instantaneous frequency measurement is improved by applying offset voltage compensation to the comparator circuits to compensate the frequency-dependent path loss of the delay line and the frequency dependence of power detection.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.9
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• pp.47-54
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• 2004

The previous works for WLAN system based on OFDM is mainly individual study for independent frequency offset or symbol synchronization. In this paper, the performance of IEEE 802.11a WLAN(Wireless Local Area Network) system in the realistic indoor multipath channel models is analyzed with frequency offset compensation and channel estimation methods. For the performance analysis of the WLAN system indoor Rayleigh multipath channels are adopted, and the BER(Bit Error Rate) of WLAN system is calculated with y2 code-rate 16-QAM based on standard specification. From the simulation results, the difference of required Eb/No for BER of 10-3 is 1-2dB between the channel estimation and frequency offset compensation, and perfect channel estimation and no frequency offset.

• Journal of Advanced Navigation Technology
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• v.26 no.2
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• pp.72-77
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• 2022

Among the techniques of reinforcement learning, Q-Learning means learning optimal policies by learning Q functions that perform actionsin a given state and predict future efficient expectations. Q-Learning is widely used as a basic algorithm for reinforcement learning. In this paper, we studied the effectiveness of selecting and learning efficient paths by designing policies and rewards based on Q-Learning. In addition, the results of the existing algorithm and punishment compensation policy and the proposed punishment reinforcement policy were compared by applying the same number of times of learning to the 8x8 grid environment of the Frozen Lake game. Through this comparison, it was analyzed that the Q-Learning punishment reinforcement policy proposed in this paper can significantly increase the learning speed compared to the application of conventional algorithms.

• Korean Journal of Optics and Photonics
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• v.32 no.6
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• pp.259-265
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• 2021

Recently, lens manufacturing and assembly technology has greatly improved. However, tight requirements of manufacturing and assembly lead to an increase in cost and manufacturing time, and in some cases the performance of an optical system may deteriorate depending on the operating environment's conditions, such as temperature or vibration. In addition, the use of a compensator is an effective method to reduce sensitivity in an ultra-precision optical system, but in the case of a small lens, such as that in an endoscope, it is difficult to use a compensator due to the size limitation of the lens barrel. Therefore, minimizing lens sensitivity is the most important technology in lens design. For this reason, there have been various attempts to reduce the lens sensitivity, and there is a trend to add functions to reduce the sensitivity in the lens design S/W. In this paper, we introduce a design technology that minimizes lens sensitivity. We first design a lens with quite good performance, then analyze the sensitivity of this lens, make a multi-configuration with high-sensitivity element error, and then reoptimize it. We prove with an example that this design technique is very effective.

• Journal of Korea Society of Industrial Information Systems
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• v.28 no.2
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• pp.31-45
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• 2023

This study deals with exploring qualitative steps and paths that appear as YouTube users' usage time increases quantitatively. For the study, I applied theories from psychology and neuroscience, subdivided the interval between the personalization algorithm of the recommendation system, and active use and analyzed the relationship between variables in this process. According to the theory behavioral model theory (FBM), variable reward, and dopamine addiction were applied. Personalization algorithms easy clicks as triggers according to associated content presentation functions in behavioral model theory (FBM). Variable rewards increase motivational effectiveness with unpredictability of the content you search, and dopamine nation is summarized as stimulating the dopaminergic nerve to continuously and actively consume content. This study is expected to make an academic and practical contribution in that it divides the purpose of use of content in the personalization algorithm and active use section into four stages from a psychological perspective: first use, reuse, continuous use, and active use, and analyzes the path.