• The Journal of the Korea Contents Association
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• v.19 no.2
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• pp.469-476
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• 2019

Robotic motion is designed by the rotation and the translation of multiple joint coordinates in a three-dimensional space. Joint coordinates are generally modeled by homogeneous transform matrix. However, the complexity of three dimensional motions prefers the visualization methods based on simulation environments in which models and generated motions work properly. Many simulation environments have the limitations of usability and functional extension from platform dependency and interpretation of predefined commands. This paper proposes the web-based three dimensional simulation environment toward high user accessibility. Also, it covers the small size web server that is linked with Python script. The non linearities of robot control apply to verify the computing efficiency, the process management, and the extendability of user scripts.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.257-259
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• 2012

친환경 시대로 나아가는 현재, 능동소음제어는 저주파소음을 줄이기 위한 좋은 방법이다. 또한 수동소음제어만으로 선박소음을 제어하기에는 물리적인 무게가 심각히 가중되어 한계를 가지게 된다. ANC 시스템은 이러한 문제를 해결해 줌과 더불어 다양하게 변화하는 환경소음까지 줄여주는 특성을 가지고 있다. 우리는 본 논문에서 선박의 환경소음을 줄이기 위하여 LMS 알고리즘과 신경회로망 알고리즘을 기반으로하는 ANC 시스템을 제안한다. 먼저 선박과 유사한 유도전동기의 소음을 측정하고 다음으로 ANC 시스템을 위한 LMS 구조를 구축한다. 그리고 소음의 비정치와 불확실성 때문에 단층 퍼셉트론 모델로 디자인된 신경회로망 알고리즘을 추가하여 실시간으로 소음을 줄이도록 하였다. 이 하이브리드 ANC 시스템은 최급강하기법의 방법으로 파라미터 값들이 온라인으로 실시간 추정되며, 제안된 ANC 시스템은 컴퓨터 시뮬레이션을 이용하여 그 성능을 분석하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.768-771
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• 2008

컴퓨터를 활용한 제어 기술이 발달함에 따라 무인화 시스템이 증가하고 있는 현실이다. 이 논문에서는 현재 많은 연구가 활발히 이루어지고 있는 무인화 시스템들 중의 하나인 무인 자동 주차 시스템을 위한 기법을 제안하고 시뮬레이션 실험을 통하여 그 가능성을 보였다. 제안한 자동 주차 시스템에서는 센서 정보를 입력으로 하고 퍼지 함수에 의한 추론 결과를 활용하여 조향 장치를 제어하는 방식을 제안하였다. 성능 평가를 위하여 그래픽 시뮬레이션 환경을 구축하고 제안한 기법을 이용한 가상자동차의 주차 과정을 보였으며 그 결과를 분석하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.9
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• pp.1172-1179
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• 2020

With the establishment of the railway integrated radio network (LTE-R) environment, radio-based train control transmission and reception and various forms of service are provided. The smooth delivery of these services requires improved performance in a highly reliable and available wireless environment. This paper measured the LTE-R radio communication environment to improve radio communication performance of railway integrated wireless network reliability and availability, analyzed the results, and established the wireless environment model. Based on the built-up model, we also proposed an improved radio-access algorithm to control trains for improved reliability, suggesting a way to improve stability for handover that occur during open-air operation, and proposed an algorithm for frequency auto-heating to improve availability. For simulation, data were collected from the Korea Rail Network Authority (Daejeon), Manjong-Gangneung KTX route, which can measure the actual data of LTE-R wireless environment, and the results of the simulation show performance improvement through algorithm.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.1
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• pp.88-93
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• 2020

Recently, SDN technology is applied to real communication business, users are getting bigger, and as the amount of data flowing in the network increases, interest in network data flow management is increasing. During this process, it must be ensured that the confidentiality, integrity, availability, and traceability of the data on the network being transmitted. In addition, it is necessary to develop an environment for observing the flow of data in real time on a network required in various fields and visually confirming the control. In this paper, first, Mininet is applied to construct a network topology and various environment attributes. Second, we added OpenDayLight in Mininet environment to develop a simulation environment to visually check and control network traffic flow in network topology.

• Journal of the Korea Society for Simulation
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• v.23 no.4
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• pp.181-188
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• 2014

Heterogeneous physical systems and computational devices are incorporated on a large-scale in a CPS (cyber-physical system) environment. Simulations can be useful for the reliable behaviors of CPSs. Time synchronization is one of major technical issues for the simulations. In the CPS, distributed systems control themselves by interacting with each other during runtime. When some simulation models have high complexity, wrong control commands as well as incorrect data can be exchanged due to the time error. We propose a time synchronization algorithm for the hybrid model that has characteristics of both continuous time systems and discrete event systems. In addition, we develop a CPS simulator based on our algorithm. For the verification of the algorithm and the execution of the simulator, we develop an example hybrid model and simulate considering user controls as well as interactions among the distributed systems.

• Journal of the Korea Society for Simulation
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• v.15 no.1
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• pp.11-17
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• 2006

This paper shows a case study of designing a PLC logic simulator that was developed to simulate and verify PLC control programs for nuclear plant systems. The nuclear control system requires strict restrictions rather than normal process control system does, as it works with a high-risky and dangerous nuclear plant. One is that it should assure the safeness of the control programs by exploiting severe testing. The other restriction is that the control programs should be executed fast enough such that they could control multi devices concurrently in real-time. To cope with these restrictions, we devised a logic compiler which generates C-code programs from given PLC logic programs. Once the logic program was translated into C-code, the program could be analyzed by conventional software analysis tools and could be used to construct a fast logic simulator after cross-compiling, in fact, that is a kind of compiled-code simulator.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11a
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• pp.233-236
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• 2002

Computational steering system은 계산 및 응용 과학자들이 컴퓨터를 이용해서 보다 효과적이고 효율적인 방법으로 시뮬레이션을 진행하고 제어하기 위해서 제안되었다. 하지만 시간이 흐를수록 시뮬레이션의 규모가 커지면서 단일 컴퓨터 시스템으로 시뮬레이션을 수행하는 것이 어렵게 되었다. 이 문제를 해결하기 위해서 최근 새로운 형태의 슈퍼컴퓨팅 환경으로 주목받기 시작한 그리드와 computational steering system을 연계하는 방법에 대한 연구가 진행되고 있다. 본 논문에서는 computational steering system의 개념과 함께 그리드에서 운용 가능한 대표적인 computational steering system을 소개하고 KISTI 슈퍼컴퓨팅센터에서 구축하고 있는 국가 그리드 기반인 N* Grid를 위한 computational steering system의 구현 방향을 제시하고자 한다.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.485-496
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• 2022

Modern agriculture is being transformed into smart agriculture to maximize production efficiency along with changes in the 4th industrial revolution. However, rural areas in Korea are facing challenges of aging, low fertility, and population outflow, making it difficult to transition to smart agriculture. Among ICT technologies, simulation allows users to observe or experience the results of their choices through imitation or reproduction of reality. The combination of the three-dimension (3D) model and the greenhouse simulator enable a 3D experience by virtual greenhouse for fruits and vegetable cultivation. At the same time, it is possible to visualize the greenhouse under various cultivation or climate conditions. The objective of this study is to apply the greenhouse climate management model for simulation development that can visually see the state of the greenhouse environment under various micrometeorological properties. The numerical solution with the mathematical model provided a dynamic change in the greenhouse environment for a particular greenhouse design. Light intensity, crop transpiration, heating load, ventilation rate, the optimal amount of CO₂ enrichment, and daily light integral were calculated with the simulation. The results of this study are being built so that users can be linked through a web page, and software will be designed to reflect the characteristics of cladding materials and greenhouses, cultivation types, and the condition of environmental control facilities for customized environmental control. In addition, environmental information obtained from external meteorological data, as well as recommended standards and set points for each growth stage based on experiments and research, will be provided as optimal environmental factors. This simulation can help growers, students, and researchers to understand the ICT technologies and the changes in the greenhouse microclimate according to the growing conditions.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.04a
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• pp.110-114
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• 1999

본 연구는 Zeigler가 제안한 이산 사건 시스템 형식론(DEVS: Discrete Event System Specification)을 이용한 거시적 및 미시적 교통류 시뮬레이션 방법론의 개발을 주 목적으로 한다. 도로 교통망의 모델링 방법은 미시적(microscopic)방법과 거시적(macroscopic)방법으로 분류된다. 이러한 모델링 방법들은 그 목적에 따라 각기 표현되어 제각기 사용되어 왔으나, 시스템 이론적으로 이들은 독립적 모델이 아니며 오히려 이들은 서로 동질적 추상화 관계에 있어서, 통합 모델링 환경의 구축시 미시적 모델들로부터 추상화에 의한 거시적 모델의 자동생성 등 설계상의 효율뿐 아니라 모델간의 일관성을 통한 모델 유효성을 보장할 수 있는 장점이 제공될 수 있다. 따라서, 본 논문에서는 서로 다른 표현 방법(즉, 이산시간 형식론과 이산사건 형식론)간의 통합 표현을 기반으로 양자간의 추상화 관계를 도출하고, 이를 이용한 모델 추상화를 통해 거시적 및 미시적 교통류 시뮬레이션 방법론을 제안한다. 시스템 이론적 접근을 토대로 접근한 통합 교통류 시뮬레이션 환경은 미국 Berkeley 대학 교통 연구소에서 개발한 SHIFT 등과 같은 최첨단 교통류 시뮬레이션 도구에 비하여 SES/MB를 기반을 시스템 이론적이며 소프트웨어공학적인 접근을 통하여, 1) 기존 제어 방식의 검증 및 신뢰도 분석, 2) 각종 사건, 사고의 시간별 파급효과 분석, 3) 도로건설 계획안에 대한 타당성 검토, 4) 운전자 및 관리자를 위한 예측된 교통정보 등을 제공할 수 있을 것으로 기대된다.