• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.4
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• pp.12-22
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• 1999

본 논문에서는 PCS의 확장개념으로 최근 관심이 높아지고 있는 In-Building PCS에서 가입자 이동성향과 이동 트래픽 특성을 이용해서 시스템의 트래픽 성능을 분석하였다. 이를 위해 빌딩내 적절한 셀 모양을 설정하고 가입자 이동성을 수학적으로 모델링하였으며 모델링된 셀에서의 가입자 이동률을 다양한 이동 파라메터로서 정의하고 이로부터 2차원 Morkov 생성-소멸 상태도를 유도하였다. 마지막으로 모델링된 가입자 이동성과 트랙픽 상태도를 통해 셀 내에서의 트래픽 성능을 분석하고 평가하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.9A
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• pp.1609-1613
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• 2001

본 논문에서는 실시간 자기 상관 관계를 이용하여 주파수 도약 시점을 찾아내는 epoch 추정기를 소개하고 이것의 성능을 tone jamming 환경 하에서 분석해 보았다. 주파수 도약 방법을 이용하는 시스템은 주로 군 관련 시스템이므로 jamming 환경 하에서의 성능이 매우 중요하다. Jamming이 있을 경우 epoch 추정기는 실제 값보다 작은 값을 나타내는 것을 알 수 있었다. 분석 과정을 수학적으로 유도하였고, 컴퓨터 실험으로 결과를 확인하였다.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.37-40
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• 2000

This paper deal with a movable boundary multiple access scheme and frame format for ATM over satellite. By mathematical modeling and simulation, we can see that suggested frame format is suitable for non-realtime traffic users.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.1
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• pp.153-160
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• 2022

A greedy algorithm is proposed to select a subset of nodes of a graph for bandlimited graph signals in which each signal value is generated with its weight. Since graph signals are weighted, we seek to minimize the weighted reconstruction error which is formulated by using the QR factorization and derive an analytic result to find iteratively the node minimizing the weighted reconstruction error, leading to a simplified iterative selection process. Experiments show that the proposed method achieves a significant performance gain for graph signals with weights on various graphs as compared with the previous novel selection techniques.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.6
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• pp.71-81
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• 2011

Unlike a typical internal combustion engine vehicle, the powertrain system of the pure electric vehicle, consisting of battery, inverter and motor, has direct effects on the vehicle performance and dynamics. Then, the specific modeling of such complex electro-mechanical components enables the insight into the longitudinal dynamic outputs of the vehicle and analysis of entire powertrain systems. This paper presents the dynamic model of electric vehicle powertrain systems based on theoretical approaches to predict and analyze the final output performance of electric vehicles. Additionally, the correlations between electric input signals and the final output of the mechanical system are mathematically derived. The proposed model for powertrain dynamics of electric vehicle systems are validated with a reference electric vehicle model using generic simulation platform based on Matlab/Simulink software. Consequently, the dynamic analysis results are compared with electric vehicle simulation model in some parameters such as vehicle speed/acceleration, and propulsion forces.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.564-568
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• 2008

In this paper, MAC(Medium Access Control) algorithm for the IEEE 802.11 DCF(Distributed Coordination Function) improving the performance is proposed and analyzed mathematically. The MAC of IEEE 802.11 WLAN to control data transmission uses two control methods called DCF and PCF(Point Coordination Function). The DCF controls the transmission based on CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance). The DCF shows excellent performance relatively in situation that competition station is less but has a problem that performance is fallen from throughput and delay viewpoint in situation that competition station is increased. This paper proposes an enhanced DCF algorithm that increases the CW to maximal CW after collision and decreases the CW smoothly after successful transmission in order to reduce the collision probability by utilizing the current status information of WLAN. To prove efficiency of proposed algorithm, a lots of simulations are conducted and analyzed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.41-48
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• 2006

An anti-collision algorithm is very important in the RFID system because it decides tag identification time and tag identification accuracy. We propose improved anti-collision algorithms using Bin slot in RFID system. In the proposed algorithms, if the reader memorizes the Bin slot information, it can reduce the repetition of unnecessary PingID command and the time to identify tags. If we also use ScrollA11ID command in the proposed algorithm, the reader knows the sequence of collided E bits. Using this sequence, the reader can reduce the repetition of PingID command and tag identification time. We analyze the performance of the proposed anti-collision algorithms and compare the performance of the proposed algorithms with that of the conventional algorithm. We also validate analytic results using simulation. According to the analysis, for the random tag n, comparing the proposed algorithms with the conventional algorithm, the performance of the proposed algorithms is about $130\%$ higher when the number of the tags is 200. And for the sequential tag ID, the performance of the conventional algorithm decreases. On the contrary, the performance of the proposed algerian using ScrollA11ID command is about $16\%$ higher than the case of using random tag ID.

• Communications of Mathematical Education
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• v.37 no.2
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• pp.233-256
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• 2023

This study conducted foundational research to derive ways to use ChatGPT in mathematics education by analyzing ChatGPT's responses to questions from the National Assessment of Educational Achievement (NAEA) and the College Scholastic Ability Test (CSAT). ChatGPT, a generative artificial intelligence model, has gained attention in various fields, and there is a growing demand for its use in education as the number of users rapidly increases. To the best of our knowledge, there are very few reported cases of educational studies utilizing ChatGPT. In this study, we analyzed ChatGPT 3.5 responses to questions from the three-year National Assessment of Educational Achievement and the College Scholastic Ability Test, categorizing them based on the percentage of correct answers, the accuracy of the solution process, and types of errors. The correct answer rates for ChatGPT in the National Assessment of Educational Achievement and the College Scholastic Ability Test questions were 37.1% and 15.97%, respectively. The accuracy of ChatGPT's solution process was calculated as 3.44 for the National Assessment of Educational Achievement and 2.49 for the College Scholastic Ability Test. Errors in solving math problems with ChatGPT were classified into procedural and functional errors. Procedural errors referred to mistakes in connecting expressions to the next step or in calculations, while functional errors were related to how ChatGPT recognized, judged, and outputted text. This analysis suggests that relying solely on the percentage of correct answers should not be the criterion for assessing ChatGPT's mathematical performance, but rather a combination of the accuracy of the solution process and types of errors should be considered.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.253-260
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• 2009

This paper, mathematically analyzes the performance of newly proposed TR-UWB system which the frequency components of a UWB pulse were processed so that the system could be implemented with ADCs of a few MHz sampling rate, and presents the comparison with an existing frequency-domain based TR-UWB system. The comparison is mainly based on the SNR ratio which depends on the mean and the variance of the frequency components. We also shows that the simulation results to support the theoretical analysis where the comparison is made under the IEEE 802.15.3a channel model as well as AWGN channel.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.568-571
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• 2022

본 논문에서는 서술형 수학 문제의 자동 풀이 기술 개발을 위한 데이터 증강 기법인 MOO 를 제안한다. 서술형 수학 문제는 일상에서의 상황을 수학적으로 기술한 자연어 문제로, 인공지능 모델로 이 문제를 풀이하는 기술은 활용 가능성이 높아 국내외에서 다양하게 연구되고 있으나 데이터의 부족으로 인해 성능 향상에서의 한계가 늘 존재해 왔다. 본 논문은 이를 해결하기 위해 시중의 수학 문제들을 수집하여 템플릿을 구축하고, 템플릿에 적합한 풀이계획을 생성할 수 있는 중간 언어인 MOOLang 을 통해 생성된 문제에 대응하는 Python 코드 형태의 풀이와 정답을 생성할 수 있는 데이터 증강 방법을 고안하였다. 이 기법을 통해 생성된 데이터로 기존의 최고 성능 모델인 KoEPT를 통해 학습을 시도해본 결과, 생성된 데이터셋을 통해 모델이 원활하게 데이터셋의 분포를 학습할 수 있다는 것을 확인하였다.