• Journal of Korean Society of Transportation
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• v.22 no.6
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• pp.175-196
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• 2004

This study focuses on improving the performance of freeway incident detection by introducing some new measures to reduce false alarms in developing a new incident detection model. The model consists of the 5 major components through which a series of decision makings in determining the given traffic flow condition are made. The decision making process was designed such that the causes of traffic congestions can be accurately classified into several types including incidents and bottlenecks according to their unique characteristics. The model performance was tested and found to be compatible with that of the existing well-recognized models in terms of the detection rate and detection time. It should noted that the model produced much less false alarms than most of the existing models. The study results prove that the initial objective of the study was satisfied as it was an experimental trial to improve the false alarm rate for the incident detection model to be more pactically usable for traffic management purposes.

• Journal of Korean Society of Transportation
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• v.24 no.4 s.90
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• pp.129-148
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• 2006

The objective of this thesis is to develop a capacity analysis and to develop a methodology to evaluate Level of Service over the entire freeway sections by single MOE (Measure of Effectiveness) This study set forth from a following viewpoint. to analyze entire freeway sections as freeway facility system, it is important to identify the exact point where congestion would occur and the extent of the congestion. Therefore, in this thesis, congestion mechanism on freeways was figured out and congestion analysis methodology was developed. Thereby maximum possible throughput rate and maximum throughput rate in bottleneck sections were calculated and a congestion analysis was carried out. The difference between the new method and existing Procedures is that maximum possible throughput rate and maximum throughput rate. that can be considered as capacities of un-congested and congested flow in the bottleneck section, are variable capacities dependent on demand flow.

• Korea journal of population studies
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• v.22 no.1
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• pp.93-121
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• 1999

이 연구는 인천의 정체성을 알아보는 데 연구의 초점을 맞추었다. 연구방법으로는 실증적 방법과 민속학적 방법 두 가지를 병행하였다. 시민단체, 공무원, 학생을 대상으로 임의목적표본방법을 사용하여 총 613명이 분석되었다. 분석방법은 교차통계분석 및 다중분류분석을 하였다. 정체성은 한 지역에 거주하는 주민들의 집단결속력과 성취도를 결정하여 주며, 그 지역의 사회적 통합과도 밀접한 관련을 지니고 있어서, 지역의 문제나 관심사를 해결하고 발전시키는데 가장 핵심적인 요소이다. 인천의 정체의식은 세 집단 모두 낮으며, 전체응답자의 절반 이상은 그저 그렇다는 중용의 의견이었다. 인천에 대한 정체의식을 응답집단의 특성별로 보면 여자보다는 남자가 높고, 기혼자보다는 미혼자가 높으며, 30세 이상으로 연령이 많을수록, 수입과 생활수준이 낮을수록 정체의식이 상대적으로 높게 나타났다. 그리고 전문.관리.사무직보다는 판매.서비스.생산.농업직 종사자들의 정체의식이 높았다. 전문대 정도의 교육을 받은 시민의 정체의식이 상대적으로 높고, 인천의 문화.복지.환경개선을 위한 특별기금 기부의사가 있는 시민과 인천을 마음붙이고 살 곳으로 생각하는 시민의 정체의식이 높다. 총괄적인 의미에서 본 인천의 정체성에 관한 조사를 보면, 인천은 "주인의식 없음"과 "이제부터 만들어 가야 한다"는 답변이 제일 많았고 그 다음은 "포용력", "선구적 개척정신", "긍정적인 의미의 짠물", "합중시(合衆市)적 다양성", "외세에 대한 호국정신", "세계의 관문도시"로 나타났다. 이와 같은 응답유형으로 보아서는 인천지역에 대한 이미지를 한마디로 딱 잘라 말하기는 어렵다. 그러나 인천은 서울.경기인, 충청인, 호남인, 영남인, 이북인, 외국인 등을 가리지 않고 받아드리는 "포용력이 있는 합중시적 다양성을 가진 도시"로 지역차가 서로 다른 출신성분이 공존할 수 있다는 점에서 의미하는 바가 크다. 이는 "세계속의 도시"와 "동북아의 거점도시"를 추구하는 미래지향적인 시각에서는 지역주의를 지양하고 지역통합이슈와 세계화 물결속에서 외국인에게도 열린 상태문화를 제공하는 관문이 될 것이라는 면에서 인천이 추구해야 할 정체성으로 시사하는 점이라고 본다.는 미래지향적인 시각에서는 지역주의를 지양하고 지역통합이슈와 세계화 물결속에서 외국인에게도 열린 상태문화를 제공하는 관문이 될 것이라는 면에서 인천이 추구해야 할 정체성으로 시사하는 점이라고 본다.

• Journal of Energy Engineering
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• v.13 no.1
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• pp.28-33
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• 2004

The objective of the study was to investigate the characteristics of heat transfer and flow in 2-dimensional impinging air jet system, in which trapezoid rods have been set up in front of impinging plate in order to increase heat transfer. Experiments were carried out first using without the rods to establish the baseline heat transfer performance. And this result compared with the experimentation with rods. When rods are installed in front of the impinging plate, the acceleration of the flow and the eddies due to the rods seem to contribute to the heat transfer enhancement. Heat transfer performance was best under the condition of C=1 n and as the pitch is 30 mm. In this case, maximum rate of heat transfer augmentation is about 1.62 times greater compared to that without trapezoid rods.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.5
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• pp.40-51
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• 2020

Much time has passed since Korea's expressway congestion-threshold speed was revised in 2011. In the meantime, various expressway environments have changed owing to improved performance of vehicles, expanded operations of transport competition (i.e., the KTX), and increased speed limits along some expressway sections. In addition, the speed that expressway users expect to travel at is also increasing. Therefore, through a survey, this study investigates expressway users' perceptions of congestion, and reviews the adjustment of the expressway speed congestion threshold by analyzing expressway traffic flow. One result of the survey confirms that the threshold speed expressway users consider to be congestion has slightly increased. Analyzing traffic and speed data through a K-means algorithm found that the threshold speed for congestion is 60 km/h. In addition, assuming the congestion threshold speed increase from 40 km/h to 50 km/h and 60 km/h, frequently congested expressway sections are identified, determining that 50 km/h is appropriate as a congestion threshold for proper expressway mobility management.

• School Mathematics
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• v.16 no.2
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• pp.303-315
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• 2014

Even though the variety of expressions are dealt with in Korean elementary mathematics, the systematization of the subject matter of expressions is still insufficient. This is basically due to the failure of revealing clearly the identity of expressions dealt with in elementary mathematics. In this paper, as a groundwork to improve this situation, after the classification of signs as elements constituting expressions, in a position to consider elementary mathematics using transitional signs such as ${\square}$, ${\triangle}$, etc and words or phrases in expressions, expressions were defined and classified based on that classification of signs. It can be presented as the conclusion that the following four judgements which helps to promote the systematization of the subject matter of expressions are possible through this definition and classifications. First, by clarifying the identity of the expressions, any mathematical clauses or sentences can be determined whether those are expressions or not. Second, Forms of expressions can be identified. Third, the subject matter of expressions can be identified systematically. Fourth, the hierarchy of the subject matter of expressions can be identified.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.3
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• pp.1-11
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• 2010

Traffic broadcasting is using a usual traffic information announcement when giving its information to users on the road and for the provision of information useful to drivers, a clear criteria of how to judge with information from informers needs to be established from the perspective of users. In this study, to give some available criteria for current announcement which often causes confusion, cognitive characteristics were investigated and analyzed based on judgment criteria which are commonly felt by correspondents, participants in traffic broadcasting and drivers. The result requires the provision of information that is relied on an average speed where drivers feel little cognitive difference and found a classification where a smooth traffic flow is more than 60km/h, going slow 40~60km/h and congested state less than 40km/h respectively. And from the study of 35 traffic information announcement for different traffic situations, 8 cases of smooth state and 9 cases of congested state were clearly classified but the rest 18 cases of comment were ambiguously perceived by drivers and which requires the necessity of a announcement that uses directly the word of 'smooth', 'slow', and 'congestion' in the actual expression of slow driving. The future study should be focused on the establishment of more definite criteria by representation of nearly real traffic flow, provision of traffic information announcement and the analysis of cognitive response through car dynamic simulators and the kinds.

• Solar Energy
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• v.13 no.1
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• pp.1-10
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• 1993

The purpose of this research is to investigate the characteristics of heat transfer in the downward axisymmetric free water jet system impinged on a flat oblique plate which has the uniform heat flux. Experimental conditions considered were Reynolds number, distance between nozzle and Bat plate, inclination angle of heater surface and nozzle exit velocity. Local Nusselt number was subjected to the influence of Re number, Pr number, oblique angle of heating surface and local position of flat plate. In the wall region of downward surface, The secondary peak point of heat transfer appeared at the local point of X/D=-8 from the stagnation point. The stagnation heat transfer rate of this experimental study augments 2.4 times than that of laminar theorical solution. The stagnation nusselt number is function of Reynolds number, nozzle-plate spacing Prandtl number and oblique angle of impinging plate.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.115-126
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• 2009

The lane-change behavior usually consists of discretionary lane-change and mandatory lane-change types. For the first type, drivers change lanes selectively to maintain their own driving condition and the second type is the case that the drivers must change the current lane, which can occur in recurrent congestion sections like merging and weaving sections. The mandatory lane-change behavior have a great effect on the operation condition of freeway. In this paper, we first generate data such as traffic volumes, speeds, densities, and the number of lane-change within the merging and weaving sections using the data of individual vehicle collected from time-lapse aerial photography. And then, the data is divided into the stable and congested flow by analyzing the speed variation pattern of individual vehicles. In addition, the number of lane-changing from ramp to mainline within every 30-meter interval is investigated before and after traffic congestion at study sites and the distribution of lane-changing at each 30-meter point is analyzed to identify the variation of lane-changing ratio depending on the stable and congested flows. To recognize the effect of mainline flow influenced by ramp flow, this study also analyzes the characteristics of the lane-changing distributions within the lanes of mainline. The purpose of this paper is to present the basic theory to be used in developing a lane-changing model at the merging and weaving sections on freeways.

• Journal of Korean Society of Transportation
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• v.22 no.2 s.73
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• pp.87-93
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• 2004

A five-day work week has a great impact on the life styles of employed persons and their families. At the same time, the changes also impact on the transportation system because travel patterns, demand, and pattern of congestion change during weekends. The negative impacts on the transportation system should be examined in order to conceive measures to maintain dependable levels of service during weekends. The first step to pursue the issue is to identify the road segments heavily affected by augmented leisure trips. In this study, characteristics of highway segments are engineered by principal analysis using data from TCS database. Scores from principal analysis are employed to distinguish highway segments for leisure trips from total 197 segments considered in this study. In addition, indexes from principal analysis are proposed to identify highway segments for leisure trips.