Earticle

기존의 Greedy 경로 프로토콜은 일반적으로 차량 Ad-hoc 통신 (Vehicle Ad-hoc Networks) 에서 좋은 성능을 보인 다. 그러나 일시적으로 거리를 비게 만드는 교통신호가 존재하는 구간이나 분리된 도로가 합류하는 지점이 없는 도시의 도로에서 지형적인 영향으로 Greedy 라우팅 프로토콜은 잘못된 경로 라우팅 된 경우 불필요하게 경로가 길어지거나 라 우팅 실패가 많이 발생한다. 또한, 단순하게 목적지 노드와의 직선거리를 가지고 노드들의 우선순위를 부여하고 가장 낮 은 값을 가진 노드를 중계노드로 선택한다. 최근에 차랑 Ad-hoc 통신에서는 지리적인 환경의 특성 때문에 거리뿐만 아 니라 전달 방향도 중요한 요소 중에 하나이다. 그래서 본 논문은 개선된 프로토콜을 제안 하는데 하나의 노드가 패킷을 전달할 때 목적지 노드 까지를 지능적으로 거리 및 전달 방향성을 고려하여 다음 노드를 선정하고 교통 통신 상태를 지 능적 제어에 따라 보다 안정적인 경로 설정을 할 수 있게 하고 지형적 모델이 따라 자유롭게 변경이 가능 하게끔 관리 한다. 제안된 프로토콜 방법의 성능 분석은 두 가지의 이동모델을 적용한 네트워크 시뮬레이션을 통하여 검증하였고 대 부분의 경우 기존 프로토콜보다 좋은 성능을 보였다.

Greedy protocols show good performance in Vehicular Ad-hoc Networks (VANETs) environment in general. But they make longer routes causing by surroundings or turn out routing failures in some cases when there are many traffic signals which generate empty streets temporary, or there is no merge roads after a road divide into two roads. When a node selects the next node simply using the distance to the destination node, the longer route is made by traditional greedy protocols in some cases and sometimes the route ends up routing failure. Most of traditional greedy protocols just take into account the distance to the destination to select a next node. Each node needs to consider not only the distance to the destination node but also the direction to the destination while routing a packet because of geographical environment. The proposed routing scheme considers both of the distance and the direction for forwarding packets to make a stable route. And the protocol can configure as the surrounding environment. We evaluate the performance of the protocol using two mobility models and network simulations. Most of network performances are improved rather than in compared with traditional greedy protocols.

In this paper, a practical bushing model is proposed to improve the accuracy of the vehicle dynamic analysis. The results of the rubber bushing are used to develop an empirical bushing model with an artificial neural network. A back propagation algorithm is used to obtain the weighting factor of the neural network. Since the output for a dynamic system depends on the histories of inputs and outputs, Narendra algorithm of 'NARMAX' form is employed to consider these effects. A numerical example is carried out to verify the developed bushing model. Then, a full car dynamic model with artificial neural network bushings is simulated to show the feasibility of the proposed bushing model.

인구밀도가 타 국가 대비 높은 대한민국은 방사능 유출 등 재난 발생 시 대규모 인명피해로 이어질 수 있다. 이에 따라 재난 상황 시뮬레이션 또는 최적 대피경로 도출 연구가 다수 수행되고 있다. 그러나, 이러한 연구들에서 활용한 도로네트워크 자료는 대부분 가상의 자료이거나 네트워크의 공 간적 범위가 작다는 한계가 존재한다. 본 연구에서는 경상권 전체를 포괄하는 실제 도로네트워크 자료를 기반으로 거리, 통행량, 수단 등 다양한 변수를 고려해 방사능 재난 발생 시 대피상황에 대한 다양한 시나리오를 구성했다. 그 후, 개별 시나리오에 대한 시뮬레이션을 수행하여 링크평균시간, 링크평균통행량, 대피소요시간 등을 도출하였다. 분석 결과는 다음과 같이 요약된다. 첫 번째, 그림 자 대피율은 대피소요시간에 큰 영향을 주지 못한다. 두 번째, 목적지와의 거리가 멀수록 대피시간이 많이 소요된다. 세 번째, 전체 구호소보다는 일부 구호소로 대피하는 것이 대피소요시간을 줄일 수 있다. 네 번째, 사고 진앙지와 인접한 EPZ 지역에서는 가급적 버스를 이용하는 것이 대피소요시간을 감소시키는 데 도움이 된다.

South Korea, which has a higher population density than other countries, can lead to massive human costs in the event of a disaster such as a radiation leakage. Accordingly, a number of studies have been conducted to simulate disaster situations or derive optimal evacuation routes. However, most of the road network data used in these studies are virtual or small. In this study, actual road network data from the entire Gyeongsang region were used. In addition, various scenarios for evacuation situations in the event of a radiation leakage were constructed in consideration of various variables such as distance, traffic volume, and modes. The analysis results are summarized as follows. First, as a result of performing the simulation, the shadow evacuation rate does not significantly affect the evacuation time. Second, the farther the destination, the more evacuation time it takes. Third, evacuating to some aid stations rather than the entire aid station can reduce the time required for evacuation. Fourth, in the EPZ area, using buses as much as possible helps reduce evacuation time.

PURPOSES : The aim of this study was to compare the performance of the QUEENSOD method and the gravity model in estimating Origin-Destination (O/D) tables for a large-sized microscopic traffic simulation network. METHODS : In this study, an expressway network was simulated using the microscopic traffic simulation model, VISSIM. The gravity model and QUEENSOD method were used to estimate the O/D pairs between internal and between external zones. RESULTS: After obtaining estimations of the O/D table by using both the gravity model and the QUEENSOD method, the value of the root mean square error (RMSE) for O/D pairs between internal zones were compared. For the gravity model and the QUEENSOD method, the RMSE obtained were 386.0 and 241.2, respectively. The O/D tables estimated using both methods were then entered into the VISSIM networks and calibrated with measured travel time. The resulting estimated travel times were then compared. For the gravity model and the QUEENSOD method, the estimated travel times showed 1.16% and 0.45% deviation from the surveyed travel time, respectively. CONCLUSIONS : In building a large-sized microscopic traffic simulation network, an O/D matrix is essential in order to produce reliable analysis results. When link counts from diverse ITS facilities are available, the QUEENSOD method outperforms the gravity model.

CIS nations are recognized as an emerging market recently because there are abundant natural resources and a lot of investment demand. Furthermore, they are located in the middle of Europe and Asia and that make them have more strategic importance as a logistics hub. So many global companies including domestic ones began to advance into the on-site. and this tendency will be strong. On the contrary, a research in logistics environment of CIS has rarely been done. This paper provides a way of systematic approach to design logistics network in CIS with real business case and shows the analyzed result of optimization simulation that includes factors having a huge influence on the overall logistics cost.

수자원 관리를 위해 주로 사용되는 물리 모형은 입력자료의 구축과 구동이 어렵고 사용자의 주관적 견해가 개입될 수 있다. 최근 수자원 분야에서 이러한 문제점을 보완하기 위해 기계학습과 같은 자료기반 모델을 이용한 연구가 활발히 진행되고 있다. 본 연구에서는 관측자료만을 이용하여 강원도 삼척시 오십천 유역의 장기강우유출모의를 수행했다. 이를 위해 기상자료로 3개의 입력자료군(기상관측요소, 일 강수량 및 잠재증발산량, 일강수량 - 잠재증발산량)을 구성하고 LSTM (Long Short-term Memory)인공신경망 모델에 각각 학습시킨 결과를 비교 및 분석했다. 그 결과 기상관측요소만을 이용한 LSTM-Model 1의 성능이 가장 높았으며, 여기에 MLP 인공신경망을 더한 6개의 LSTM-MLP 앙상블 모델을 구축하여 오십천 유역의 장기유출을 모의했다. LSTM 모델과 LSTM-MLP 모형을 비교한 결과 두 모델 모두 대체적으로 비슷한 결과를 보였지만 LSTM 모델에 비해 LSTM-MLP의 MAE, MSE, RMSE가 감소했고 특히 저유량 부분이 개선되었다. LSTM-MLP의 결과에서 저유량 부분의 개선을 보임에 따라 향후 LSTM-MLP 모델 이외에 CNN등 다양한 앙상블 모형을 이용해 물리적 모델 구축 및 구동 시간이 오래 걸리는 대유역과 입력 자료가 부족한 미계측 유역의 유황곡선 작성 등에 활용성이 높을 것으로 판단된다.

Physical models, which are often used for water resource management, are difficult to build and operate with input data and may involve the subjective views of users. In recent years, research using data-driven models such as machine learning has been actively conducted to compensate for these problems in the field of water resources, and in this study, an artificial neural network was used to simulate long-term rainfall runoff in the Osipcheon watershed in Samcheok-si, Gangwon-do. For this purpose, three input data groups (meteorological observations, daily precipitation and potential evapotranspiration, and daily precipitation - potential evapotranspiration) were constructed from meteorological data, and the results of training the LSTM (Long Short-term Memory) artificial neural network model were compared and analyzed. As a result, the performance of LSTM-Model 1 using only meteorological observations was the highest, and six LSTM-MLP ensemble models with MLP artificial neural networks were built to simulate long-term runoff in the Fifty Thousand Watershed. The comparison between the LSTM and LSTM-MLP models showed that both models had generally similar results, but the MAE, MSE, and RMSE of LSTM-MLP were reduced compared to LSTM, especially in the low-flow part. As the results of LSTM-MLP show an improvement in the low-flow part, it is judged that in the future, in addition to the LSTM-MLP model, various ensemble models such as CNN can be used to build physical models and create sulfur curves in large basins that take a long time to run and unmeasured basins that lack input data.

Purpose: This study aimed to explore the nursing students’ experiences on a simulation based integrated practicum using a text network analysis. Methods: The data were collected from 103 questionnaires submitted by senior students who took the simulation based integrated nursing practicum course in a college of nursing during spring semester 2018. NetMiner 4.3. was used for the text network analysis. After data cleaning, frequency, degree/betweenness centrality, and subgroup analysis were used for the final analysis. Results: Situation, Patient, Skills, Coping, and Reality were the words with high frequency and centrality in practicum experience among nursing students. Comparing visualized sub-networks groups with course outcomes, ‘the collaboration with health professionals(CO4)’ were not explained by any sub-groups. Embarrassment and Mistake were the high frequency words in the analysis for negative experience. Conclusion: The results identified positive and negative experience, and the unachieved course outcomes from nursing students’ experience of simulation practicum. The results could be used for improving the quality of simulation based integrated nursing practicum.

본 논문에서는 무선 통신망과 향후 발전 가능성이 예상되는 가상현실 기술을 이용하여 특수환경에 적용되는 관제분야에서 사고상황 검증 및 사후 교육용도로 적용이 가능한 가상현실 시뮬레이션 기법을 이용한 관제상황 검증 시스템을 제안하였다. 또한, 제안 시스템의 정의와 동작원리를 살펴보고 제안 시스템에서 요구되는 기술사항에 관하여 분석하였다. 본 논문에서 제안한 무선 통신망을 활용한 관제상황 검증 시스템은 이동 전동차량의 기관실 모니터링 뿐만 아니라 의료분야 혹은 특수 위험물 처리를 수행하는 관제실에서도 그 적용이 가능하리라 예상된다.

In this paper, We proposed monitoring verification system using virtual reality simulation technology in monitoring fields for peculiar environment. Also, we analyzed the proposed system about required technology issues and operation process. The proposed monitoring verification system available wireless communication network is expected that application is possible in medical treatment field or special dangerous article processing filed as well as monitoring verification of mobile electric railcar

Logistics cost of domestic company has been improved continuously and annually, it is still higher than other main comparative countries. So, in this study, as optimizing the logistic network of distribution, it was trying to find methods decreasing logistics cost and storage cost, which occupies 86% of logistics cost of companies. through the efficiency of transportation and delivery routing, it could be also possible to decrease the logistics cost. And, it is also checked to find the logistics cost could be decreased by 10% by optimizing the routes of transportation and delivery, improving the transportation mode, etc

국내외적으로 V2X 통신기술을 접목한 C-ITS 사업 및 자율주행 고도화 실증연구가 활발히 진행되고 있다. 실증 초기 1단계에서는 경고메시지, 차량주행정보, 교통정보 등의 방송서비스 에서 점차 실시간성을 요구하는 군집주행, 원격주행, 인식정보공유 등의 고도화된 서비스로 발 전하고 있다. 또한, 네트워크 서비스 고도화를 위해 전송속도와 지연시간 등을 개선하기 위한 기술개발이 여러모로 진행되고 있다. 본 논문에서는 3GPP 표준 기반 C-V2X 기술을 바탕으로 안정적인 드로이드 형태의 저속 로봇의 원격주행 서비스 제공을 위해 네트워크 지연시간 측면 에서 요구사항을 분석하였다. 원격주행 성능평가를 위해 오퍼레이터를 포함한 시스템 모델링 을 통한 시뮬레이션을 수행하였고, 해당 실험 조건에서 90% 이상의 성능 만족을 위해 30ms 이내의 코어 및 액세스 네트워크 지연시간이 요구된다는 것을 알 수 있었다.

Recently, cooperative intelligent transport systems (C-ITS) testbeds have been deployed in great numbers, and advanced autonomous driving research using V2X communication technology has been conducted actively worldwide. In particular, the broadcasting services in their beginning days, giving warning messages, basic safety messages, traffic information, etc., gradually developed into advanced network services, such as platooning, remote driving, and sensor sharing, that need to perform real-time. In addition, technologies improving these advanced network services' throughput and latency are being developed on many fronts to support these services. Notably, this research analyzed the network latency requirements of the advanced network services to develop a remote driving service for the droid type low-speed robot based on the 3GPP C-V2X communication technology. Subsequently, this remote driving service's performance was evaluated using system modeling (that included the operator behavior) and simulation. This evaluation showed that a respective core and access network latency of less than 30 ms was required to meet more than 90 % of the remote driving service's performance requirements under the given test conditions.

최근 인터넷 환경에 대한 사이버 공격 위협이 증가함에 따라 개인과 기업뿐만 아니라 국가 기반 시설까지 사이버 공격의 대상이 되고 있다. 민간 기업에서는 이러한 위협을 막기 위해 사이버 공격 보안 솔루션을 제시하고, 시뮬레이션 환경을 조성하여 공격 및 방어 기법을 분석하는 등 사이버 공격에 대한 효과적인 방어책을 마련하고 있다. 하지만 군 통신망에서는 이러한 사이버 공격을 방어하기 위한 시뮬레이션 환경이 제대로 조성되어있지 못하여 사이버전대책 수립에 어려움을 겪고 있다. 따라서 본 논문에서는 OPNET 시뮬레이터의 Cyber effect 모델을 이용하여 군유선통신망 사이버 공격 방어시뮬레이션 환경을 조성하고 대표적 사이버 공격인 DDoS 공격과 이를 방어하는 트래픽 측정 기반의 IDS를 모델링한다. 또한 모델링 된 공격, 탐지 모델에 대하여 실험을 통해 성능을 검증한다. 제안하는 유선 전술통신망 시뮬레이션 방법은 사이버전 모의를 위한 환경 모델 및 사이버 공격, 방어 모델을 정립하고 검증 가능한 기반을 마련하여 사이버전 기술발전에 기여한다.

Recently cyber attacks have increased threats to the Internet. Therefore, individuals and businesses, as well as national infrastructure to have been the target of cyber attacks. The private enterprise proposed a security solution for cyber attacks in order to prevent threats. Then, establish an effective defense against cyber attacks by creating a simulation environment for analyzing cyber attacks and defensive techniques. However, in tactical network, since the simulation environment for a cyber attack does not create properly. It makes difficult to establish defensive measures to cyber attack. In this paper, using the Cyber Effect model of OPNET simulator to create a simulation environment for the tactical wired network and not only modeling the DDoS attacks of typical cyber attacks but also, traffic measurement based IDS for detect the DDoS attacks. In addition, verifying the performance experiment against a the modeled attack and defense. The proposed idea model for establishing cyber warfare simulation and contributes to the cyber warfare technology.

3GPP LTE(Long Term Evolution)/LTE-A(LTE-Advanced) are the evolution of the UMTS which are successfully commercialized in Korea and these make possible to deliver high quality multimedia services according to the users' expectations. In the more than two years since, it has been increased of a number of users and total amount of data in LTE network. And there is a limit to budget for investment of each communication company. The investment in LTE/LTE-A, it is closely related to enlarge in-building coverage. LTE/LTE-A network engineers need new Re-engineering scheme and technology to reduce cost and ensure enough in-building coverage. In this paper, we describe how to handle LTE traffic occurred in building with (Density per Sector: Non-Uniform) technique in simulation tool. And we explained on the application of different penetration loss according to the each class of building. These functions can give more reliable analysis results to increase the in-building communication quality in LTE/LTE-A.

Many of companies have made significant improvements for globalization and competitive business environment The supply chain management has received many attentions in the area of that business environment. The purpose of this study is to generate realistic production and distribution planning in the supply chain network. The planning model determines the best schedule using operation sequences and routing to deliver. To solve the problem a hybrid approach involving a genetic algorithm (GA) and computer simulation is proposed. This proposed approach is for: (1) selecting the best machine for each operation, (2) deciding the sequence of operation to product and route to deliver, and (3) minimizing the completion time for each order. This study developed mathematical model for production, distribution, production-distribution and proposed GA-Simulation solution procedure. The results of computational experiments for a simple example of the supply chain network are given and discussed to validate the proposed approach. It has been shown that the hybrid approach is powerful for complex production and distribution planning in the manufacturing supply chain network. The proposed approach can be used to generate realistic production and distribution planning considering stochastic natures in the actual supply chain and support decision making for companies.