• Korean Journal of Environment and Ecology
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• v.33 no.6
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• pp.624-635
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• 2019

Bird strike accidents, a collision between aircraft and birds, have been increasing annually due to an increasing number of aircraft operating each year to meet heavier demand for air traffic. As such, many airports have conducted studies to assess and manage bird strike risks effectively by identifying and ranking bird species that can damage aircraft based on the bird strike records. This study was intended to investigate the bird species that were likely to threaten aircraft and compare and discuss the risk of each species estimated by the single-matrix and multi-matrix risk assessment models based on the Integrated Flight Information Service (IFIS) data collected in Gimpo, Gimhae and Jeju Airports in South Korea from 2005 to 2013. We found that there was a difference in the assessment results between the two models. The single-matrix model estimated 2 species and 6 taxa in Gimpo and Gimhae Airports and 2 species and 5 taxa in Jeju Airport to have the risk score above "high," whereas the multi-matrix model estimated 3 species and 5 taxa in Gimpo Airport, 4 species and 5 taxa in Gimhae Airport, and 2 species and 3 taxa in Jeju Airport to have the risk score above "very high." Although both models estimated the similar high-risk species in Gimpo and Gimhae Airports, there was a significant difference in Jeju Airport. Gimpo and Gimhae Airports are near the estuary of a river, which is an excellent habitat for large and heavy waterbirds. On the other hand, Jeju Airport is near the coast and the city center, and small and light bird species are mostly observed. Since collisions with such species have little effect on aircraft fuselage, the impact of common variables between the two models was small, and the additional variables caused a significant difference between the estimation by the two models.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.519-526
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• 2016

As marine accidents happen frequently, it is required to establish a marine traffic monitoring system, which is designed to improve the safety and efficiency of navigation in VTS (Vessel Traffic Service). For this aim, recently, X-band marine radar is used for extracting the sea surface information and, it is necessary to retrieve wave information correctly and provide for the safe and efficient movement of vessel traffic within the VTS area. In this paper, three different current estimation algorithms including the classical least-squares (LS) fitting, a modified iterative least-square fitting routine and a normalized scalar product of variable current velocities are compared with buoy data and then, the iterative least-square method is modified to estimate wave information by improving the initial current velocity. Through several simulations with radar signals, it is shown that the proposed method is effective in retrieving the wave information compared to the conventional methods.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.3 no.1 s.4
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• pp.45-52
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• 2004

There are many cities installing ITS(Intelligent Transportation Systems) and running TMC(Trafnc Management Center) to improve mobility and safety of roadway transportation by providing roadway information to drivers. There are many devices in ITS which collect real-time traffic data. We can obtain many valuable traffic data from the devices. But it's impossible to avoid missing traffic data for many reasons such as roadway condition, adversary weather, communication shutdown and problems of the devices itself. We couldn't do any secondary process such as travel time forecasting and other transportation related research due to the missing data. If we use the traffic data to produce AADT and DHV, essential data in roadway planning and design, We might get skewed data that could make big loss. Therefore, He study have explored some imputation techniques such as heuristic methods, regression model, EM algorithm and time-series analysis for the missing traffic volume data using some evaluating indices such as MAPE, RMSE, and Inequality coefficient. We could get the best result from time-series model generating 5.0$\%$, 0.03 and 110 as MAPE, Inequality coefficient and RMSE, respectively. Other techniques produce a little different results, but the results were very encouraging.

• Journal of Korean Society of Transportation
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• v.36 no.2
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• pp.155-168
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• 2018

In this study, we studied the directional pattern of entering the intersection from the intersection upstream link prior to predicting short future (such as 5 or 10 minutes) intersection direction traffic volume on the interrupted flow, and examined the possibility of traffic volume prediction using traffic assignment model. The analysis method of this study is to investigate the similarity of patterns by performing cluster analysis with the ratio of traffic volume by intersection direction divided by 2 hours using taxi DTG (Digital Tachograph) data (1 week). Also, for linking with the result of the traffic assignment model, this study compares the impact area of 5 minutes or 10 minutes from the center of the intersection with the analysis result of taxi DTG data. To do this, we have developed an algorithm to set the impact area of intersection, using the taxi DTG data and traffic assignment model. As a result of the analysis, the intersection entry pattern of the taxi is grouped into 12, and the Cubic Clustering Criterion indicating the confidence level of clustering is 6.92. As a result of correlation analysis with the impact area of the traffic assignment model, the correlation coefficient for the impact area of 5 minutes was analyzed as 0.86, and significant results were obtained. However, it was analyzed that the correlation coefficient is slightly lowered to 0.69 in the impact area of 10 minutes from the center of the intersection, but this was due to insufficient accuracy of O/D (Origin/Destination) travel and network data. In future, if accuracy of traffic network and accuracy of O/D traffic by time are improved, it is expected that it will be able to utilize traffic volume data calculated from traffic assignment model when controlling traffic signals at intersections.

• 한국공간정보시스템학회:학술대회논문집
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• 2007.06a
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• pp.3-8
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• 2007

최근 도로 네트워크 환경에서 이동 객체 위치 정보를 관리하고 이동 객체의 미래 위치를 예측하는 이동 객체 위치 예측 시스템의 필요성이 나날이 증가되고 있다. 이동 객체위치 예측 시스템은 교통 관제 및 다양한 응급 상황 시 이동 객체의 미래 위치를 신속히 예측하기 위해 사용되며, 보다 편리한 위치 기반 서비스의 제공을 가능하게 해준다. 이러한 시스템을 위한 대부분의 미래 인덱싱 기법은 일반적으로 이동 객체의 미래 위치 예측을 위해 과거 이동 궤적을 이용하고 있다. 그러나, 수많은 이동 객체의 과거 이동 궤적 관리가 어렵고, 실시간으로 변화하는 이동 객체의 미래 궤적을 반영하기 위한 방대한 미래 인덱스의 갱신 요청으로 인해 인덱스 유지 비용이 증가하여 미래 위치 질의 요청에 대한 신속한 처리 성능이 떨어지게 된다. 따라서 본 논문에서는 이동 객체 위치 예측 시스템에서 방대한 이동 객체의 과거 이동 궤적으로부터 효율적으로 미래 위치를 예측하기 위해 셀 기반의 미래 인덱싱 방법인 PFCT-Tree(Probability Future Cell Trajectory-Tree)를 제시한다. PFCT-Tree는 방대한 과거 이동 궤적을 셀 단위로 재구성하여 인덱스 크기를 줄이고, 셀 내부 경험치를 기반으로 장기간 질의 시 빠른 미래 위치를 예측할 수 있다. 또한 신속한 미래 이동 궤적의 갱신 속도를 향상시키기 위해 미래 시간을 미래 궤적과 분리하여 인덱싱함으로써 위치 예측 오류로 인한 미래 인덱스 갱신 비용을 최소화 할 수 있다. 마지막으로 실험을 통해 도로 네트워크 환경에서 PFCT-Tree가 기존 인덱싱 기법들보다 갱신 및 검색 성능이 우수함도 입증하였다.ential oil (Bergamot, Grapefruit, Lemon, Petigrain)은 농도 의존적으로 ROS 생성을 증가시켰다. 이상의 결과를 종합하여 볼 때 citrus essential oil은 MSH에 의한 melanin 생성을 억제하는 것으로 보아 미백제로서의 개발 가능성이 있는 것으로 사료된다.가 사용될 수 있음을 제시한다.찍 발견되어 크기는 작았으며, 육안적으로 폴립의 Yamada 형태의 분류는 II, III의 형태를 띠고 있었다.EX>로 한반도 후기 백악기의 고지자기극$(Lat./Long.=70.9^{\circ}N/215.4^{\circ}E,\;A_{95}=5.3^{\circ})$의 위치와 유사하므로 암석의 생성 시기는 후기 백악기로 판단하였다. 한편 함평분지에 분포하는 백악기 화산암류에서는 한 개의 정자화 방향과 두 개의 역자화 방향이 확인되었다. 이들 특성잔류자화 방향은 백악기 화산암 형성 당시 암석에 기록된 성분으로써 당시 지구자기장의 상태를 기록한 것으로 해석하였으며, 이중 정자화 방향을 함평분지 화산암의 대표 방향으로 채택하였다 함평분지 화산암의 고지자기 극의 위치는 정자극의 경우는 $Lat./Long.=70.2^{\circ}N/199.5^{\circ}E,\;(K=18.1,\;A_{95}=9.6^{\circ})$ 이며 역자극의 경우는 $Lat./Long.=65.5^{\circ}S/251.3^{\circ}E,\;(K=7.1,\;A_{95}=20.7^{\circ})$이다. 이중 정자극의 위치는 한반도의 후기 백악기극의 위치와 통계적으로 동일한 것으로 나타나 함평분지 화산암

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.2
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• pp.36-49
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• 2016

A subway system is one of the major transportation modes at a metropolitan area. When it meets the other lines, the metro station, so-called transferring station, is usually threatened by severe pedestrian congestion and safety issue of transit users including the transportation vulnerable. Although transportation planners forecast travel demand at the beginning, it is not easy to predict pedestrian flows precisely for a long term if land use plans have dramatically changed. Due to expensive costs, structural extension of metro stations is limited. Therefore, it requires efficient and technical improvements as meeting the demand of pedestrian and physical characteristics. In this study, the core mechanism of pedestrian movement-based simulation model was introduced and evacuation scenarios were analyzed with the developed model. As a result, the multiple optimal routes for unexpected events at the solid space of the multiple stories are easily searched through the simulator and in the case of Sadang Station, travel time can be reduced by 60% when the evacuation information and intuitive design are provided.

• Journal of Korean Society of Transportation
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• v.24 no.4 s.90
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• pp.93-101
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• 2006

The signalized intersections near highway-railroad grade crossing are operated without signal preemption in Korea when trains are approaching the crossing. This signal operation is very dangerous because queues from the intersection can extend back over the track, thereby creating the Potential for a serious vehicle-train accident. And the queues from the crossing can extend to the intersection with the normal signal operation while trains Pass the crossing. In this case the intersection is disrupted, and delay and the Potential for vehicle accident increase highly In order to improve the intersection performance and Protect the accident the crossings and intersections. signal Preemption designed to provide a special control mode should be implemented. In this study it was shown that intersection Performance near highway-railroad grade crossing improved using signal preemption. When signal Preemption is implemented at the test site, the delay was reduced by about 9sec/veh. Even though there were vehicle-train accidents at the crossing in all 30 simulations without signal preemption. there was no vehicle-train accidents at all when signal preemption is used.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.379-390
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• 1994

The recent study of the delay models have assumed random arrival which has a constant average flow rate throughout the cycle. However, where signals are spaced closely together or form part of progressive system, platoon flows are common and more closely represent reality. In such cases, those results are quite different pattern of estimated delay from that of observed one. In order to solve this problem, the 1985 HCM takes Progression Adjustment Factor (PAF) into account. In the 1985 HCM, however, it has deficiencies in defining and applying it, such as platoon ratio ($R_p$) and platoon arrival type. The Purpose of this study is to investigate theoretically the predictive ability of the individual models concerned through comparing the estimated delay and PAF suggested by NCHRP Report 339, KHCM or USHCM (1985) with the observed obtained by field survey at a signalized intersection.

• International Journal of Highway Engineering
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• v.13 no.3
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• pp.157-165
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• 2011

With respect to the trend of highway traffic accident, highway accident is in decline, whileas, the fatality is on an increasing trend. Thus, many efforts to decrease highway traffic accidents and improve the safety, are required. In particular, in case of highway, the management standard by grade for accident black spot is designated. Thus, investing the effect factors by grade for highway traffic accident is required in detail. Thus, in this study, the factors affecting the traffic accidents among the environmental factors based on the graded data for the accident black spot in the applicable section targeting the Seoul-Pusan Express Highway, were reviewed; accident forecasting model which would analyze the characteristics of the accidents for determining the accident grade, was developed. As a result of establishing a model by using Quantification Theory of Type II, considering the characteristics of the dependent and independent variables based on the geometric structure, 'the fixed variable' among the variables relating to the accident, for the variables influencing over the accident grade, 'the type of vans, a chassis and people', 'the trailers, special vehicles and chassis people' and 'the negligence of watching and cloudy weather' were analyzed as common factors, in case of 'horizontal alignment', 'longitudinal slope' and, 'barricade' respectively.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.3 no.1 s.4
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• pp.53-65
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• 2004

A series of accidents, which are non-recurrent and non-anticipated, are called incidents. These incidents make standard traffic flows interrupt, which result in the decrease of road capacity and a number of social and economic costs, such as the traffic congestion and air pollution. In order to prevent the hazard of incidents, domestic and foreign traffic management center are likely to opt auto-sense system with algorithms of auto-incident sense. However, it is evaluated that the algorithms have a low function with frequent wrong alarms, even if they accurately ry to speculate the incidents. In the case of bottleneck which has lack of road capacity, compared with other roads, due to inefficient road structured over-capacity of the demand of on-off ramp, the incidents regularly take place. Nonetheless, it can be more difficult to speculate the auto-incidents sense owing to similar incidents, such as the queue of in-out flows of cars and the change of road line. Throughout this research, the function of the model has improved excluding near road line in the module of the incidents which is based on the auto-incidents algorithms during the sense of the congestion of ramp areas.