• Journal of Korean Society of Transportation
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• v.30 no.6
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• pp.93-102
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• 2012

The frequency and severity of traffic accidents related to signalized intersections in urban areas have been more serious than those in both arterial segments and crosswalks. Especially, traffic accidents involved with injuries and fatalities have caused by traffic signal violations within intersections. Therefore, many countries including Korea have installed the red light enforcement camera (RLE) to reduce traffic accidents associated with the traffic signal violation. Meanwhile, many methodologies have been studied in terms of safety impacts estimation of red light enforcement, which, however, cannot be easy to conduct. In this study, safety impacts was estimated for intersections of Chicago downtown area using SPF models and EB approach. As a result, for all crash types and target traffic accident types such as "angle", "rear end", "sideswipe in the same and other directions", "turn", and "head on", fatal crashes were reduced by 26% and 38%. However, RLE may increase property-demage-only-crashes by 3.23% and 1.16%, respectively.

• Journal of KIISE:Databases
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• v.33 no.1
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• pp.69-85
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• 2006

Broadcast has been often used to disseminate the frequently requested data efficiently to a large volume of mobile clients over a single or multiple channels. Conventional concurrency control protocols for mobile transactions are not suitable for the wireless broadcast environments due to the limited bandwidth of the up-link communication channel. In wireless broadcast environments, the server often broadcast different data items with different frequency to incorporate the data access patterns of mobile transactions. The previously proposed concurrency control protocols for mobile transactions in wireless broadcast environments are focused on the mobile transactions with uniform data access patterns. However, these protocols perform poorly when the data access pattern of update mobile transaction are not uniform but skewed. The update mobile transactions with skewed data access patterns will be frequently aborted and restarted due 4o the update conflict of the same data items with a high access frequency. In this paper, we propose an energy-efficient concurrence control protocol for mobile transactions with skewed data access as well as uniform data access patterns. Our protocol use a random back-off technique to avoid the frequent abort and restart of update mobile transactions. We present in-depth experimental analysis of our method by comparing it with existing concurrency control protocols. Our performance analysis show that it significantly decrease the average response time, the amount of upstream and downstream bandwidth usage over existing protocols.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.119-119
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• 2009

인버터 DC 저항용접의 적용성 증대 : 인버터 DC 저항용접 공법이 SPOT, PROJECTON, SEAM, BUTT 등의 공정에 다양하게 적용되어 저항용접 현장에서 고효율, 친환경적 용접 환경을 만드는데 일조 하고 있다. 특히 자동차의 경량화, 충돌내성 증대, 진동 및 내구성 증대, 공간활용 극대화, 새로운 Design 개념 적용 등의 산업전반에 걸쳐 나타나는 신 Trends로 고 장력 철재의 적용 범위가 확대되고 HSS(High Strength Steel), EHSS(Extra High Strength Steel), UHSS (Ultra High strength Steel ; Hot - Formed Steel )등 다양한 철판의 SPOT 저항용접이 필요하게 되었다. 기존의 AC 단상용접의 전력 특성 상 통전 중 무 통전 시간 과 높은 PEAK 전력, 단상 대 전력 소모로 인한 전력 DROP 등의 문제로 인하여 신소재의 용접 시 매우 많은 Spatter가 발생하고, 높은 용접품질의 확보가 어려워 지므로 이를 대체하기 위한 공법으로 MFDC ( 인버터 DC 저항용접공법 )이 적용되고 있다. 인버터 DC 저항용접의 적응제어 : MFDC라는 높은 효율의 용접 전력원이 확보 됨에도 불구하고 용접현장에서는 원 자재, 도금 등의 품질 산포, 프레스 물의 가공산포, 공기압 산포, 전극 과열 및 마모 등의 요인에 의하여 저항용접 산포가 발생하고 있다. 이는 인위적인 조작이 어렵고 불규칙적이며, 어디서나 산재하고 있는 문제이다. 이를 용접전력 제어 법으로 개선하여 일정한 용접성을 확보하기 위한 노력이 적응제어 기법이다. 정 전류, 정 전력 제어는 정량 제어로 용접 물을 비롯한 용접부의 변화와는 관계없이 설정된 일정량의 전력을 공급하기만 하는데 반하여 적응제어는 적절한 용접 작업 시의 용접 물의 상태, 전극의 가압, 표면 상태 등에 따른 변화 페턴을 기억하고 이후 진행되는 용접에 대하여 정상 페턴과의 차이를 감지 이를 보상하므로 고품질의 용접성을 보장하는 제어기법이다. 따라서 다양한 용접 산포 유발 요인에 의해 용접부의 변화가 발생한다 하여도 그 변화를 감지 하고 적절한 용접전력을 공급한다면 고품질의 용접성을 확보하는데 유용한 공법이 될 수 있다. 인버터 DC 저항용접의 SPC 관리 : SPOT 용접 시 획득할 수 있는 다양한 파라메터에 대하여 모니터링 하고 이 자료를 data 화 하여 품질 관리에 응용하게 되면 양산라인에서 반복적으로 발생되는 문제점을 확인 할 수 있고 이를 통계적 방법으로 추적 개선해 나간다면 용접 불량 감소 및 생산성 향상에 도움이 되며 작업자의 공정 능력 향상 및 기업의 기술축적에도 높은 기여를 할 수 있을 것이다. 용접 적응제어와 다양한 파라메터 모니터링이 한 system에서 이루어 질 때 높은 용접성 확보와 불량률 감소, 원가절감, 생산성 향상 등의 효과가 극대화 될 것이다.

• Korean Journal of Remote Sensing
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• v.15 no.2
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• pp.175-181
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• 1999

A recurring eddy which located at the terminal end of the Korean East Warm Current was captured on ocean color and sea surface temperature imagery from satellite in spring and autumn. During late April, 1997 thermal infrared imagery from the NOAA AVHRR sensor and ocean color data from the Japanese ADEOS-I OCTS sensor, revealed this feature. The cold core had elevated chlorophyll concentrations, based on OCTS estimates, of greater than 3 mg/m$^3$ while the warmer surrounding waters had chlorophyll concentrations of 1 mg/m$^3$ or less. The elevated cholophyll accociated with this eddy has not been previously described. The eddy is also evident in SST images from autumn, but the SST in the core is warmer than in spring, and the warm jet flowing to the west of the eddy is also warmer is autumn compared to spring. A reccurring eddy and the high chlorophyll_a concentration area which surround around the eddy show on NOAA and SeaWiFS images in March 2, 1998. The eddy forms at the northern extent of the Korean East Warm Current as those waters collide with the cold, south-flowing Liman Current over a topographic shelf about 1500 m deep. This region of the eddy formation appears to have a strong connection with the dynamics of the western part of the polar front eddy field that dominates surface mesoscale structure in the central East (Japan) Sea. Interaction of the eddy with ARGOW tracked drifters, and evidence for its persistence are discussed.

• International Area Studies Review
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• v.17 no.4
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• pp.155-179
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• 2013

Becoming independent in 1956, Sudan has since experienced a number of coups $d^{\prime}{\acute{e}}tat$, religious conflicts between the Islamic north and the Christian south, conflicts between the north-south population composition and races, two civil wars for nearly 40 years due to a clash of interests over resources and others, and the Darfur crisis in which hundreds of thousands died. In 1983, as the Sudanese government forced Islamic laws on the southern region where many Christians lived, the civil war resumed and suffered heavy casualties. Although a brief period of tranquility is maintained at the present moment as South Sudan seceded, military conflicts continue to arise. The objective of this research is to understand the North-South Sudan conflict by examining its history and course. For this purpose, chapter 2 will make a theoretical and reality approach for conflict items and solutions. Chapter 3 will discuss the historical background and reasons for the Sudanese conflict by considering Sudan before 19th century, the Egyptian conquest of Sudan and the diverging North and South, Sudanese independence and other divisions yet again, and finally the North-South conflicts over religion and resources. In Chapter 4, there will be an analysis of the course of the Sudan Civil War by separating it into the First and Second Civil War. In Chapter 5, the consequences and future prospect will be presented in lieu of the conclusion.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.478-485
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• 2018

Aids to Navigation (AtoN) is one of the marine traffic safety facilities that promotes the safety of maritime traffic and enhance ship's operational efficiency. However, functional failure of AtoN due to ship's collision or bad weather conditions leads to inconvenience or navigational risk to various users such as the ship operators. For insstance, the largest container port in Korea, Busan Port has experienced a total of 400 AtoN accidents in the past 12 years (2006-2017).Therefore, an average of 20.6 days of recovery time is required, which increases the maritime safety anxiety for AtoN users. is the objective of this study was to present the quantitative support of the users for the prevention of AtoN accidents and the improvement of the feasibility of implementing more efficient management in Korea. A survey was conducted on the users of Busan port areas to investigate general perception of AtoN in general and the accidents that have happened, and to estimate the economic value of navigational risk reduction by implementing effective AtoN management measure. Using the representative non-market valuation method for environmental or public goods known as contingent valuation method (CVM), the economic value granted to users for the AtoN services in Busan port was estimated to at least 16 billion won. Therefore, these finding could be used by AtoN managers and/or policy makers as a valuable data to identify the users' need of various AtoN services including Busan Port and to establish and implement more efficient management plan.

• Journal of International Area Studies (JIAS)
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• v.22 no.2
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• pp.47-80
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• 2018

Bosnia has a unique political and social structure of 'One State-Two Systems' according to the 'Dayton Peace Agreement'. It is true that since the end of the 1995 civil war, the problem of nation and peace in Bosnia has been attracted by the broad concept of Europe as a whole, beyond the local dimension of the Balkans. Bosnia is a typical 'Mosaic of Religion and Culture' region in Europe. And Sarajevo, the capital of Bosnia, where various religious and cultural features of Europe are gathered, is called 'Jerusalem in Europe'. For this reason Bosnia has repeated a history of cultural and religious conflict since the Middle Ages. However, before the civil war in the late 20th century, the nations in Bosnia also had experience of 'harmony among various nations, religions and cultures of East and West'. The international community, including the EU, has paid attention to this point as it promotes Bosnia's reconstruction and peace settlement. And these are working to restore the history of harmony among nations in Bosnia today. In the past, research on Bosnia has focused primarily on national conflicts between religions and cultures. However, in this study, I will try to analyze the practical cases of peace settlement and harmony among nations in Bosnia as follows: First, 'Bosnia's accession to the EU' which means active intervention and continued interest of the international community. Second, 'the resolution of war crimes and liquidation of past history' through the end of ICTY mission in December 2017. And third, 'reflection of international society and historical reconciliation of Serbia' through the reinterpretation of the Srebrenica massacre.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.1
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• pp.14-26
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• 2019

For bus drivers' safe driving, a policy that analyzes the causes of the drivers' traffic accidents and then assists their safe driving is required. Therefore, the Ministry of Land, Infrastructure and Transport set up its plan to gradually expand the equipping of commercial vehicles with FCWS (Forward Collision Warning System) and LDWS(Lane Departure Warning System), from the driver-supporting ADAS(Advanced Driver Assistance Systems). However, there is not much basic research on the analysis of bus drivers' traffic accidents in Korea. As such, the time is appropriate to research what is the most necessary ADAS for bus drivers going forward to prevent bus accidents. The purpose of this research is to analyze how serious the accidents were in the different bus routes and whether the accidents were repetitive, and to give recommendations on how to support ADAS for buses, as an improvement. A model of ordered logit was used to analyze how serious the accidents were and as a result, vehicle to pedestrian accidents which directly affected individuals were statistically significant in all of the models, and violations of regulations, such as speeding, traffic signal violation and violation of safeguards for passengers, were indicated in common in several models. Therefore, the pedestrian-sensor system and automatic emergency control device for pedestrian should be installed to reduce bus accidents directly affecting persons in the future, and education for drivers and ADAS are to be offered to reduce the violations of regulations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.4
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• pp.505-512
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• 2019

This study is a basic study to prepare safety measures for the tram that is being introduced into Korea by reviewing accident analysis and accident compensation system of the tram. Analysis of accident characteristics of the tram was analyzed based on overseas data. Five years after the inauguration of the tram, accidents were halved and stabilized. Deaths accounted for 0.5 % of all casualties, most accidents were minor. Accidents with other mean transportation were high 84.1 %, among them accidents with passenger cars was found to be highest. The frequent points of accidents were analyzed as intersections and tram stop, and measures for pedestrian accidents were found to be important. Those are proposed safety measures through analyzing tram accident characteristics: Monitoring accidents which occur within five years of its inauguration, developing accident database input system, installation of fences for preventing people from jaywalking, operating traffic signal for preventing people from jaywalking through connection of pedestrian signals and tram signals, clamping down on illegal U-turn cars and jaywalking pedestrian, Also, those are proposed accident treatment measures based on general driver receptively and overseas data: property damage liability coverage (PI) of car insurance, comparative negligence when the accident occurs between car and tram.

• Journal of Aerospace System Engineering
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• v.15 no.3
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• pp.45-56
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• 2021

Demand for UAM (Urban Air Mobility) aircraft is rapidly increasing in countries around the world due to the problem of traffic congestion in urban areas. Through research and development, various e-VTOL aircraft concepts are being prepared for commercialization, for which airworthiness certification is required, since it is a manned transportation mode for people to board. Factors that pose a fatal threat to the safe operation of UAM aircraft include lightning strikes that can cause damage to structures and disturb the navigation system, as well as icing that impairs flight stability. Since the current UAM aircraft-related lightning and icing certification technology development is insufficient, there is need to develop appropriate airworthiness certification guidelines. In this study, after analyzing the laws and regulations related to aircraft by the FAA and the EASA, we tried to incorporate the lightning and icing certification guidelines for the UAM aircraft. We also analyzed the effects of lightning and icing on UAM aircraft using computational simulation, and presented the basis for establishing practical guidelines for the certification of UAM aircraft to be adopted in the future.