• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.131-140
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• 2011

Proxy Mobile IPv6 (PMIPv6) is designed to provide a network-based localized mobility management protocol, but it does not handle the global mobility of hosts. In this paper, we propose a location management scheme based on Domain Name System (DNS) for PMIPv6. In this proposed scheme, DNS as a location manager provides PMIPv6 for global mobility. In addition, a paging extension scheme is introduced to PMIPv6 in order to support large numbers of mobile terminals and enhance network scalability. To evaluate the proposed location management scheme, we establish an analytical model, formulate the location update and the paging cost, and analyse the influence of the different factors on the total signalling cost. The performance results show how the total signal cost changes under various parameters.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.2
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• pp.800-813
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• 2021

With the advent of 5G communications, internet of vehicles technology has been widely used in vehicles. Then the dynamic spread of information between vehicles began to come into focus with more research. It is well known that the identification of nodes with great spread influence has always been a hot topic in the field of information spreading. Most of the existing work measures the propagation influence by degree centrality, betweenness centrality and closeness centrality. In this paper, we will identify influential vehicle nodes based on the mobility characteristics of vehicles to explore the information spreading between vehicles in VANETs. Different from the above methods, we mainly explore the influence of the radius of gyration and vehicle kilometers of travel on information spreading. We use a real vehicle trajectory data to simulate the information transmission process between vehicles based on the susceptible-infected-recovered SIR model. The experimental results show that the influence of information spreading does not enhance with increasing radius of gyration and vehicle kilometers of travel. The fact is that both the radius of gyration and the distance travelled have a significant influence on information spreading when they are close to the median. When the value of both is large or small, it has little influence on information spreading. In view of this results, we can use the radius of gyration and vehicle kilometers of travel to better facilitate the transmission of information between vehicles.

• Journal of Advanced Navigation Technology
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• v.26 no.5
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• pp.281-288
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• 2022

This study quantitatively analyzed the human casualties that can occur when a multicopter-type Urban Air Mobility (UAM) with a weight of about 1 ton and a speed of about 100 km/h falls in an urban area. Based on the population density and building database in Seoul, the population exposed to collisions in the event of a UAM crash was derived. Through the ballistic descent model, the accident impact radius of the UAM fall was calculated. In addition, the change in human casualties on the ground was analyzed when the accident impact radius increased. Finally, the ground risk map was created for Seoul, and it was confirmed that about 1 to 10 people could be injured when a UAM crash.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.2
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• pp.456-477
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• 2024

With information technology's rapid development, the Internet faces serious security problems. Studies have shown that malware has become a primary means of attacking the Internet. Therefore, adversarial samples have become a vital breakthrough point for studying malware. By studying adversarial samples, we can gain insights into the behavior and characteristics of malware, evaluate the performance of existing detectors in the face of deceptive samples, and help to discover vulnerabilities and improve detection methods for better performance. However, existing adversarial sample generation methods still need help regarding escape effectiveness and mobility. For instance, researchers have attempted to incorporate perturbation methods like Fast Gradient Sign Method (FGSM), Projected Gradient Descent (PGD), and others into adversarial samples to obfuscate detectors. However, these methods are only effective in specific environments and yield limited evasion effectiveness. To solve the above problems, this paper proposes a malware adversarial sample generation method (PixGAN) based on the pixel attention mechanism, which aims to improve adversarial samples' escape effect and mobility. The method transforms malware into grey-scale images and introduces the pixel attention mechanism in the Deep Convolution Generative Adversarial Networks (DCGAN) model to weigh the critical pixels in the grey-scale map, which improves the modeling ability of the generator and discriminator, thus enhancing the escape effect and mobility of the adversarial samples. The escape rate (ASR) is used as an evaluation index of the quality of the adversarial samples. The experimental results show that the adversarial samples generated by PixGAN achieve escape rates of 97%, 94%, 35%, 39%, and 43% on the Random Forest (RF), Support Vector Machine (SVM), Convolutional Neural Network (CNN), Convolutional Neural Network and Recurrent Neural Network (CNN_RNN), and Convolutional Neural Network and Long Short Term Memory (CNN_LSTM) algorithmic detectors, respectively.

• Journal of Korean Society for Quality Management
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• v.17 no.2
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• pp.81-92
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• 1989

A class of standard optimization techniques to estimate the stationary transition probabilities among states is discussed. With the use of aggregate time series data on employed labor in industrial sectors, the alternative restricted estimates including minimum absolute deviation, unweighted, weighted, generalized inverse, minimum chi-square and maximum likelihood are evaluated and compared. Analytic and numerical results are shown favorably with the viewpoint of the validity and predictive potentiality of model.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.847-849
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• 2004

애드혹 네트워크에서 그룹 이동성을 고려할 경우, 주요한 이슈 중 하나가 그룹의 파티션 문제이다. 파티션 시간의 예측을 위해서, 기존의 모델들은 파티션이 발생하는 두 그룹의 대칭적 이동을 가정한다. 그러나, 실제 상황에서 파티션은 다양한 방향으로 일어나므로 대칭적 방향만을 고려한다면, 정확한 파티션 시간을 예측할 수 없다. 본 논문은 대칭적 이동뿐만 아니라, 모든 방향을 고려한 네트워크 파티션 분석 모델을 제시하고 수학적인 분석을 통해 이를 증명한다. 따라서, 정확한 파티션 시간의 예측이 가능하다.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.457-460
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• 1998

단 채널 MOSFET 소자의 드레인 전압-드레인 전류 특성을 예측하기 위해서 caughey-thomas 이동도 모델을 수치적으로 구현하는 방법을 제안한다. 구현된 caughey-thomas 모델의 정확한 특성을 검증하기 위해서 0.5[.mu.m]의 설계규칙을 가즌 ASIC용 공정으로 n-MOSFET과 p-MOSFET을 제작하였다. 전자 및 정공의 포화속도 값이 각각 6.2*10/sup 6/[cm/sec] 과 1.034*10/sup 7/[cm/sec]인 경우에 채널길이가 0.5[.mu.m] 이상인 n-MOSFET과 p-MOSFET의 드레인 전압-드레인 전류특성의 모의실험 결과는 측정값에 비하여 10% 이내의 상대오차를 보였다.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.115.3-115
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• 2002

To improve the performance of the tracked vehicle system, we examined the feasibility of using the preview control for the tracked vehicles suspension system. We proposed a method to apply a linear optimal preview control to the tracked vehicle system. To avoid the complexity of modeling the track subsystem and kinematical nonlinearity in the trailing arm suspension, we classified these as unknown dynamics and disturbances. We used the Time Delay Control(TDC) method to make sprung mass dynamics follow that of linear preview controlled tracked vehicle model by compensating the uncertainties and disturbances. We have verified by the computer simulation that the proposed method shows good robus...

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.165-168
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• 2001

고 전계하에서 수직 및 수평 전계의 영향을 고려할 수 있는 Hewlett-Packard 이동도 모델을 구현하였다. HP 이동도 모델은 BANDIS에 구현되었다. 구현된 HP이동도 모델을 검증하기 위해 N-MOSFET과 P-MOSFET에 대해 모의실험을 수행하여 MEDICI와 비교한 결과, 드레인 전압-드레인 전류는 5% 이내의 최대 상대 오차를 보였고 전위 분포는 5% 이내의 최대 상대오차를 보였다. MEDICI에서는 1회 수렴을 하기위해 평균 4.6회 이하의 행렬 연산이 필요한 반면 BANDIS에서는 평균 4.3회 이하의 행렬 연산이 필요하다.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.899-902
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• 1999

본 논문에서는 다수 반송자에 의해 일어나는 산란현상을 고려한 반송자-반송자 산란(CCS) 이동도 모델을 구현하였다. 구현된 CCS 이동도 모델을 검증하기 위해 N/sup ＋/P 접합 다이오드에 대해 모의실험 한 후 MEDICI와 비교한 결과 장벽전위인 0.9〔V〕 미만과 이상에서 각각 2%와 6% 정도의 상대오차를 보였다. BJT의 콜렉터에 30〔V〕를 인가한 후 베이스 전압을 0.8〔V〕까지 증가시켜 모의실험 한 결과 베이스 전압베이스 전류 및 베이스 전압-컬렉터 전류 특성은 각각 4.41%, 6.10%의 최대 상대오차를 보였다.