• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.2
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• pp.29-40
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• 2010

Car simulation by TRANSIMS is able to rapidly analyze the broad area based on CA(Cellular Automata) theory, which is the great advantage compared to other existing programs. As the source code of TRANSIMS is open, it may be modified by incorporating the network and traffic characteristics. This study uses the traffic thematic map built in the Korean National Traffic DB(KTDB) center among input date used for building network data of TRANSIMS. However, because the traffic thematic map is not composed as the type required by TRANSIMS, it was corrected and complemented to build a network, and the traffic volume at arterial roads and the traffic volume at each direction of the intersection was calculated through simulation for the area of Suseong-Gu, Daegu Metro. This was compared to the actual traffic volume. As a result of the simulation, it shows error from 14% to 42% at intersection, and from 3% to 8% at arterial roads. This result is very satisfactory because the entire traffic volume of Daegu Metro was not considered, and the tendency of drivers avoiding path due to construction on certain section, the status of road surface and chronic congestion was not reflected.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6D
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• pp.785-791
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• 2011

Two-lane and two-way traffic flow shows various dynamic relationships according to the behaviors of low-speed vehicle and overtaking. And it is essential to develop a vehicle model which simultaneously explains the behaviors of low-speed vehicle and overtaking using opposite lane in order to microscopically analyze various two-lane and two-way traffic flows by traffic flow simulation. In Korea, some studies for car-following and lane-changing models for freeway or signalized road have been reported, but few researches for the development of vehicle model for two-lane and two-way highway have been done. Hence, a microscopic two-lane and two-way vehicle model was, in this study, developed with the consideration of overtaking process and is based on CA (Cellular Automata) which is one of discrete time-space models. The developed model is parallel combined with an adjusted CA car-following model and an overtaking model. The results of experimental simulation showed that the car-following model explained the various macroscopic relationships of traffic flow and overtaking model reasonably generated the various behaviors of macroscopic traffic flows under the conditions of both opposite traffic flow and stochastic parameter to consider overtaking. The vehicle model presented in this study is expected to be used for the simulation of more various two-lane, two-way traffic flows.

• Journal of Korean Society of Transportation
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• v.22 no.4 s.75
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• pp.147-158
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• 2004

A class of SWP(Stochastic Wane Propagation) models microscopically mimics individual vehicles' stochastic behavior and traffic jam propagation with simplified car-following models based on CA(Cellular Automata) theory and macroscopically captures dynamic traffic flow relationships based on statistical physics. SWP model, a program-oriented model using both discrete time-space and integer data structure, can simulate a huge road network with high-speed computing time. However, the model has shortcomings to both the capturing of low speed within a jam microscopically and that of the density and back propagation speed of traffic congestion macroscopically because of the generation of spontaneous jam through unrealistic collision avoidance. In this paper, two additional rules are integrated into the NaSch model. The one is SMR(Stopping Maneuver Rule) to mimic vehicles' stopping process more realistically in the tail of traffic jams. the other is LAR(Low Acceleration Rule) for the explanation of low speed characteristics within traffic jams. Therefore, the CA car-following model with the two rules prevents the lockup condition within a heavily traffic density capturing both the stopping maneuver behavior in the tail of traffic jam and the low acceleration behavior within jam microscopically, and generates more various macroscopic traffic flow mechanism than NaSch model's with the explanation of propagation speed and density of traffic jam.

• Spatial Information Research
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• v.22 no.2
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• pp.53-62
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• 2014

The floor field model is the micro pedestrian model based on a cellular automata for modeling pedestrian movement in the interior space using the static and dynamic floor field. It regards a form of pedestrian as square but the actual pedestrian's shape and size are similar to ellipsoid or rectangle. Because of this, we are difficult to give a rotation effect to pedestrians and there is a limit to reflect an impact of clogging and jamming. Also, this model is not able to reflect an impact of a posture and visibility effectively in the pedestrian movement. In this study, we suggest the improved pedestrian model incorporating the actual shape and size of pedestrian. The pedestrian's shape is defined not square but rectangle which is close to the actual body size of Korean. Also, we define the model which is able to represent the impact of clogging and jamming between pedestrians by adding the pedestrian's posture. We develop the simulator for testing the suggested model and study the difference between two models by comparing a number of effects. As a result, we could confirm solving the problem with dynamic value in the existed model and reflecting the panic effect in evacuation situation.

• Journal of Korean Society of Transportation
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• v.21 no.1
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• pp.91-102
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• 2003

There are two goals in this paper. The one is development of existing CA(Cellular Automata) model to explain more realistic deceleration process to stop. The other is the application of the updated CA model to forecasting simulation to predict short term link travel time that takes a key rule in finding the shortest path of route guidance system of ITS. Car following theory of CA models don't makes not response to leading vehicle's velocity but gap or distance between leading vehicles and following vehicles. So a following vehicle running at free flow speed must meet steeply sudden deceleration to avoid back collision within unrealistic braking distance. To tackle above unrealistic deceleration rule, “Slow-to-stop” rule is integrated into NaSch model. For application to interrupted traffic flow, this paper applies “Slow-to-stop” rule to both normal traffic light and random traffic light. And vehicle packet method is used to simulate a large-scale network on the desktop. Generally, time series data analysis methods such as neural network, ARIMA, and Kalman filtering are used for short term link travel time prediction that is crucial to find an optimal dynamic shortest path. But those methods have time-lag problems and are hard to capture traffic flow mechanism such as spill over and spill back etc. To address above problems. the CA model built in this study is used for forecasting simulation to predict short term link travel time in Kangnam district network And it's turned out that short term prediction simulation method generates novel results, taking a crack of time lag problems and considering interrupted traffic flow mechanism.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.2
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• pp.1-13
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• 2016

In an effort to establish adaptive measures for low carbon use and climate change, this study developed storylines for shared socio-economic reference pathways(SSP) and simulated change in land use for each storyline. First, cellular automata modeling was performed using past data, and a transition rule for the local characteristics of each planning area under study was derived by comparing with the results of the base year. Second, three storylines were formulated based on the hypothesized change in land use for the SSP. SSP1, the scenario for sustainability, assumed that the land was developed into a compact city, SSP2 assumed the development of a road through the middle of the land while maintaining the current situation, and SSP3 assumed unsustainable development into a fragmented world. Third, change in land use depending on planning area was predicted by integrating the SSP scenarios with cellular automata(CA) modeling. According to the results of analysis using the SSP scenarios, the urban area ratio increased slightly up to 2020 in SSP1 and up to 2030 in SSP2 and did not change any more subsequently, but it increased continuously until 2050 in SSP3 that assumed low level urban planning. These results on change in land use are expected to contribute towards making reasonable decisions and policies on climate change, and the outcomes of simulation derived from spatial downscaling, if applied to vulnerability assessment, will be useful to set the priority of policies on climate change adaptation.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.2
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• pp.319-326
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• 2020

PRNGs(Pseudorandom number generators) are essential for generating encryption keys for to secure online communication. A bitstream generated by the PRNG must be generated at high speed to encrypt the big data effectively in a symmetric key cryptosystem and should ensure the randomness of the level to pass through the several statistical tests. CA(Cellular Automata) based PRNGs are known to be easy to implement in hardware and to have better randomness than LFSR based PRNGs. In this paper, we design PRNGs based on PMLCA(Programable Maximum Length CA) that can generate effective key sequences in symmetric key cryptosystem. The proposed PRNGs generate bit streams through nonlinear control method. First, we design a PRNG based on an (m,n)-cell PMLCA ℙ with a single complement vector that produces linear sequences with the long period and analyze the period and the generating polynomial of ℙ. Next, we design an (m,n)-cell PC-MLCA based PRNG with two complement vectors that have the same period as ℙ and generate nonlinear sequences, and analyze the location of outputting the nonlinear sequence.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.4
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• pp.819-826
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• 2018

The generalized Hamming weight is one of the important parameters of the linear code. It determines the performance of the code when the linear codes are applied to a cryptographic system. In addition, when the block code is decoded by soft decision using the lattice diagram, it becomes a measure for evaluating the state complexity required for the implementation. In particular, a bit-parallel multiplier on finite fields based on trinomials have been studied. Cellular automata(CA) has superior randomness over LFSR due to its ability to update its state simultaneously by local interaction. In this paper, we deal with the efficient synthesis of the pseudo random number generator, which is one of the important factors in the design of effective cryptosystem. We analyze the property of the characteristic polynomial of the simple 90/150 transition rule block, and propose a synthesis algorithm of the reversible 90/150 CA corresponding to the trinomials $x^2^n+x^{2^n-1}+1$($n{\geq}2$) and the 90/150 reversible CA(RCA) corresponding to the maximum weight polynomial with $2^n$ degree by using this rule block.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.06a
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• pp.570-573
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• 2001

본 논문에서는 선형 TPMACA C의 0-tree에서 0이 아닌 상태를 여원벡터로 갖는 CA C'를 분석하여 C의 모든 상태가 C'의 어느 곳에 있는지를 밝혔으며 또한 C의 상태전이 그래프에서 한 경로만 알면 나머지 상태론 알 수 있음을 밝혔다.

• The Transactions of the Korea Information Processing Society
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• v.5 no.7
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• pp.1783-1790
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• 1998

두가지 상태값 (0, 1)과 서로 다른 네가지 경계조건을 갖는 비선형 셀룰러 오토마타 CA-6의 동적양상을 고정점과 상태 천이 그래프를 생성하는 재귀식의 관점에서 규명하였다. 특히 발견된 재귀식은 다음과 같다.