• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.922-925
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• 2004

Bluetooth technology is essentially a method for wireless connection of a diverse set of devices ranging from PDAs, mobile phone, notebook computers, to another equipments. The bluetooth system supports both point-to-point connection and point-to-multipoint connections. In point-to-multipoint connection, the channel is shared among several bluetooth devices. Two or more devices sharing the same channel form a piconet. There is one master device and up to seven active slave devices in a piconet. The radio operates in the unlicensed 2.45GHz ISM band. This allows users who travel world-wide to use bluetooth equipments anywhere. Since the link is based on frequency-hop spread spectrum, multiple channels can exist at the same time. The Bluetooth standard has been suggested that Bluetooth equipments can be used in the short-range, maximum 100 meters . It has been defined that the time takes to setup and establish a bluetooth connection among devices is 10 seconds. It is a long time and may be a cause to lose a chance of finding other non-fixed devices. We propose a routing protocols for scatternets which can be used to control a mobile units(MUs) in this network. The proposed routing protocol is composed of two kinds of bluetooth information, access point(AP) and MU.

• 산업경영시스템학회지
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• 제28권2호
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• pp.8-17
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• 2005

This paper dealt with a kind of heterogeneous vehicle routing problem with known demand and time deadline of customers. The customers are supposed to have one of tight deadline and loose deadline. The demand of customers with tight deadline must be fulfilled in the deadline. However, the late delivery is allowed to customers with loose deadline. That is, the paper suggests a model to minimize total acquisition cost, total travel distance and total violation time for a fleet size and mix vehicle routing problem with time deadline, and proposes a heuristic algorithm for the model. The proposed algorithm consists of two phases, i.e. generation of an initial solution and improvement of the current solution. An initial solution is generated based on a modified insertion heuristic and iterative Improvement procedure is accomplished using neighborhood generation methods such as swap and reallocation. The proposed algorithm is evaluated using a well known numerical example.

• 산업경영시스템학회지
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• 제34권1호
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• pp.1-8
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• 2011

Controlling industrial vehicle operated by human in warehouse was not simple since the information transfer for controlling the vehicle was not easy. However, as the technology for the WMS (Warehouse Management System) has been advanced and the PDA (Personal Digital Assistant) has come into wide use in a workplace, the control of man-operated vehicle became less difficult as do to AGVS (Automated Guided Vehicle System). This study examines the ways to improve the efficiency of warehouse operation through introducing rule of task assignment for the vehicles, particularly forklift. This study, basically, refer to AGV operation policy because a great number of studies for AGV dispatching rule have been done and the mechanism for the controlling vehicles is very similar. The workers in field prefer to simple dispatching rules such as Shortest Retrieval Time First (SRTF), Shortest Travel Time First (STTF), and Longest Waiting Time First (LWTF). However, these rules have potential disadvantage. Thus, several rules made up by combining rules mentioned above are introduced and these new rules use threshold value or evaluation formula. The effectiveness of these new rules are tested by simulation and the results are compared. This study proposes favorable dispatching rules for forklift in warehouse for the efficiency of the vehicle operation and stability of service level.

• 농업과학연구
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• 제40권1호
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• pp.53-59
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• 2013

Analysis of load data during field operations is highly important for optimum design of power drive lines for agricultural tractor. Objective of the paper was to analyze field load data using FFT to determine frequency and the energy levels of meaningful cyclic patterns. Rotary tillage, plowing, baling, and wrapping operations were selected as major field operations of agricultural tractor. An agricultural tractor with power measurement system was used. The tractor was equipped with strain-gauge sensors to measure torque of four driving axles and a PTO axle, speed sensors to measure rotational speed of the driving axles and an engine shaft, pressure sensors to measure pressure of hydraulic pumps, an I/O interface to acquire the sensor signals, and an embedded system to calculate power requirement. In rotary tillage, calculated frequency was decreased as travel speed increased. In baler operation, calculated frequency was increased as PTO speed was increased. The calculated peak frequency levels and expected levels were similar. Results of the study would provide information on power utilization patterns and on better design of power drive lines.

• 대한임베디드공학회논문지
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• 제19권2호
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• pp.91-99
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• 2024

Collision avoidance system is important to improve the robustness and functional safety of autonomous vehicles. This paper proposes an object-level distance estimation method to develop a collision avoidance system, and it is applied to golfcarts utilized in country club environments. To improve the detection accuracy, we continually trained an object detection model based on pseudo labels generated by a pre-trained detector. Moreover, we propose object-aware depth estimation (OADE) method which trains a depth model focusing on object regions. In the OADE algorithm, we generated dense depth information for object regions by utilizing detection results and sparse LiDAR points, and it is referred to as object-aware LiDAR projection (OALP). By using the OALP maps, a depth estimation model was trained by backpropagating more gradients of the loss on object regions. Experiments were conducted on our custom dataset, which was collected for the travel distance of 22 km on 54 holes in three country clubs under various weather conditions. The precision and recall rate were respectively improved from 70.5% and 49.1% to 95.3% and 92.1% after the continual learning with pseudo labels. Moreover, the OADE algorithm reduces the absolute relative error from 4.76% to 4.27% for estimating distances to obstacles.

• 대한교통학회지
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• 제29권6호
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• pp.129-136
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• 2011

VMS는 대안경로의 현황정보를 제공하는 정보수단의 역할뿐만 아니라, 경로선택에 영향을 줌으로써 통행 분산효과를 내는 제어 측면의 역할도 수행한다. 그러나 대안경로간 최적의 통행배분을 유도할 수 있는 VMS 제어기 없이, 교통관리 업무를 담당하는 센터 운영자 개인의 경험에 의존하여 대처하고 있는 실정이다. 퍼지 제어는 수학적 모델로 표현되기 어려운 복잡하고 애매한 시스템에 대하여, 전문가의 경헙적 지식이나 실제 실험 데이터에 의해 제어시스템의 규칙 또는 제어알고리즘을 만들 수 있는 장점이 있다. 이에 이러한 퍼지 제어의 장점을 살려 대안경로간 통행시간 균형을 달성할 수 있는 VMS 피드백 제어기를 설계하고 MATLAB/Simulink를 이용하여 그 성능을 검증하였다. 본 연구에서 제시한 제어기는 통행시간 균형이라는 제어목표에 수렴하고 있으나, 유출입교통량 증가와 Driver Compliance Rate 감소 등 외란에 민감하게 반응하여 수렴시간 과도하게 증가하는 현상이 나타났다. 이러한 외란에 보다 강한(Robust) 제어기로의 성능개선을 향후과제 남겨두며, 본 연구 결과를 발전시켜 실제 현장의 VMS 운영에 적용한다면 교통운영기술 진일보에 기여할 수 있을 것으로 기대된다.

• 대한교통학회지
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• 제31권1호
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• pp.25-35
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• 2013

국내거주 외국인에게 실질적으로 필요하고, 선호하는 교통안전서비스에 제공을 위해 본 연구에서는 교통사고 분석과 외국인 통행실태 조사를 시행하여 외국인의 교통사고 위험도를 파악하고 아울러 외국인이 원하는 개선방향을 제시하고자 한다. 구조방정식 모형의 주요 연구결과, 교통사고 위험도에는 교통지리 이해도가 (-)0.29, 교통법규 이해도가 (-)0.17의 영향을 미치는 것으로 분석되었으며, 정책필요도에는 교통수단 이해도가 0.25, 교통사고 위험도가 0.29의 영향을 미치는 것으로 분석되었다. 또한, 교통사고 위험도는 정책 이용의향에 0.38(직접효과 0.09, 간접효과 0.29), 정책 필요도는 0.74의 영향을 미치는 것으로 분석되었고, 정책이용 의향은 외국인 교통안전서비스 정책 효과에 0.35의 영향을 미치는 것으로 분석되었다. 따라서 외국인 교통안전서비스 정책은 교통안전교육이 약 88%, 맞춤형 다문화지구가 약 85%, 포털교통정보가 약 75% 정도 관측변수(내생변수)들에 의하여 설명되는 것으로 분석되었다. 본 연구는 기존 연구와는 달리 외국인 교통안전에 영향을 미치는 다양한 변수들에 대한 종합적이고, 구조적이며, 체계적인 분석과 모형화 과정을 통해 외국인 교통안전정책의 효과와 우선순위를 정량적으로 도출한 의의를 가지고 있다.

• 한국경제지리학회지
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• 제21권4호
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• pp.335-349
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• 2018

본 연구의 목적은 시간이 경과하면서 통행속도와 같은 교통환경에 나타나는 변화가 대중교통이용자의 시간거리 접근성에 미치는 영향을 분석하는 것이다. 이를 위하여 서울대도시권 대중교통체계의 3개년(2011년, 2013년, 2015년)의 각각 1주일치 통행기록을 담은 교통카드 데이터를 활용한다. 교통카드빅데이터에는 대중교통이용자들의 통행궤적에 대한 시 공간 정보가 담겨 있다. 본 연구에서는 교통카드 자료의 통행시간을 토대로 각 시점의 대중교통체계를 구성하고 있는 지하철 역 및 버스 정류장들 사이의 링크들의 시간거리를 산출한다. 실험 결과로 얻어진 통합 교통망에서 접근도 변화는 두 가지 관점으로 요약할 수 있다. 첫째, 해가 지날수록 접근도는 떨어지는 경향이 있다. 교통망이 더 복잡해짐으로 차량의 이동 속도가 저하되기 때문이다. 둘째, 요일별 접근도 변화 분석에서 주말에 접근도가 높아지는 경향이 있다. 이것은 버스노선들 상의 버스 속도가 주말에 빨라지기 때문이다. 접근도 변화의 분석을 위해 연도별과 요일별 차량속도와 승객수를 그래프로 설명한다.

• 한국ITS학회 논문지
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• 제14권1호
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• pp.22-30
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• 2015

최근 교통문제를 완화하기 위하여 ITS를 적용하는 도로가 늘어나고 있다. 특히 가변전광표지(VMS: Variable Message Sign)는 전방도로상황, 기상상황 등 교통정보를 제공하여 교통흐름관리 및 교통안전관리를 하는 ITS 중 하나이다. 이런 VMS의 교통정보제공의 교통안전효과를 분석하기 위하여 현장조사를 통해 데이터를 수집하고 수집된 데이터에 대한 통계학적 검증을 시행하였다. VMS 교통정보제공 전 후의 차량주행특성은 교통정보제공 시 1차로와 2차로 모두 평균주행속도가 감소하고 차로 내 차량통행이 차로중심을 기준으로 통행하는 것으로 나타났다. 또한 VMS 교통정보제공이 교통안전효과에 미치는 영향을 분석하기 위하여 교통위험지역을 선정하고 구간을 통과하는 차량에 대한 확률분포를 Anderson-Darling Test를 통해 산정하여 비교하였다. 비교결과 1차로에서 VMS 교통정보제공으로 인해 교통안전효과가 차로양쪽 각각 0.69%와 7.07% 향상되는 것으로 나타났으며, 2차로의 경우 차로양쪽 각각 2.71%와 0.02% 향상되는 것으로 분석되었다.

• 산업경영시스템학회지
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• 제39권3호
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• pp.192-203
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• 2016

Uganda is a country blessed with the biggest number of mountain Gorillas in the whole world. These animals contribute at least 12% in revenue generation to the Tourism sector through tracking by both local and foreign tourists who pay for the tracking permits. However, Gorilla tracking is also a big challenge even in the presence of highly skilled and well-trained game rangers. Development and implementation of a secure Computer and Mobile based Gorilla Tracking (GT) system that uses GIS and GPS technologies would be the most ideal technology to use. Therefore, this study aimed to find out the critical factors that would affect the Behavioral Intention of the would-be users to successfully decide to use such GIS/GPS-GT system. We used the existing UTAUT model to integrate six factors such as Performance Expectancy, Effort Expectancy, Employee Peer Influence, Facilitating Conditions, Behavioral Intention and System Use. However, Infrastructure Availability and Non-Technical Facilitating Conditions were added to reflect Ugandan ICT context. This amended UTAUT model was used to carry out the survey. The questionnaire was emailed to 220 government employees in the fields of ICT, Tour and Travel, Environmental Groups officials and Farmers who garden near the game reserves. A total of 133 were obtained fully completed, whereas 127 were deemed usable thus yielding a response rate of 58%. The analysis results show that except for non-technical facilitating conditions, effort expectancy, peer influence, performance expectancy and infrastructure availability positively affects behavioral Intention to use GIS/GPS-GT. This indicates that people in Uganda don't bother about regulations and rules in regard to using information system. As long as the system does what they want it to, anything else does not matter. As an employee in an organization is told to use a system by their supervisor, they have no objection to otherwise they risk losing their job. This implies that, supervisors have a great responsibility in the process of developing, implementing and using the system in Uganda.