• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1647-1652
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• 2008

Track geometry consists of tangent and curved lines, which caused undesirable changes in initial track geometry by traffic loads. The bigger the changes are, the worse the riding comfort and running stability of train. This is so-called track irregularity and is the most important quality parameters of ballasted track. To be able to objectively assess track irregularity, track geometry should be able to be measured. Practically, railway companies use moving chord method, this method determine versine values via a chord. The versine is the vertical distance to curve measured in the middle of the chord. This type of method measures only versine of track irregularity curve by transfer function from specific property of measuring tool. In this report, review the characteristics of two types of measuring tools by comparing the measurements. The one is GRP-1000 system, optical surveying system with Total station and lazar prism trolly. This calculates track geometry by surveying absolute coordinates of two points each on both rail heads. The other is Trackmaster, measures versine with 2m of chord length.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 지능정보 및 응용 학술대회
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• pp.95-98
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• 2008

현재 차량 내부의 기술은 최근의 환경, 에너지, 안전성 및 편리성 차원의 요구가 증대되면서 종래의 자동차 기술에 대한 변화를 가져오고 있으며 자동차산업의 패러다임을 급속히 변화시켜 나가고 있다. 이러한 기술적인 변화는 전자제어장치의 지능화는 물론 각 시스템간의 센서 네트워크를 구성하여 ITS, 텔레매틱스 등 차량 외부의 인프라 구축 시스템과 결합하여 새로운 교통시스템을 형성하고 있다. 본 논문에서는 이런 새로운 시스템 중에 핵심 기술이라고 할 수 있는 Most 차량용 네트워크와 여러 가지의 센서들을 활용한 차랑 관리 시스템 설계에 대한 기술들을 제시한다. 여러 센서에서 발생되는 정보들을 Most 네트워크를 통하여 취합하고 차량의 각 시스템의 현재 상황을 판단하고 이 정보를 운전자에게 제공함으로써 효과적인 부품 교체 시기나 차량의 안정성을 극대화시킬 수 있는 시스템을 제안한다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2013년도 춘계학술대회
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• pp.136-138
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• 2013

현재 해상교통안전시설인 표준등부표의 종류는 10가지이며, 가장 작은 등부표가 4.4m로 대형인 것이 현실이다. 따라서 제작, 교체 및 수리가 용이한 부유형의 소형 등부표를 제안하고자 하였다. 한편 부유형의 경우 환경적 외력에 의한 위치 신뢰도가 떨어지며, 특히 유실 등의 사고에 대비하기 위한 안정성 검토가 필요하다. 이 논문에서는 새로운 등부표의 운동성(Heave, Sway, Pitch)을 상용프로그램을 사용하여 Encounter Frequency별 분석하고, 2차원 경계요소법(Boundary Element Method, BEM)을 이용하여 부유체의 단면형상에 따른 유체력을 수치시뮬레이션하였다.

• Wind and Structures
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• 제29권5호
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• pp.299-312
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• 2019

Due to the rugged terrain, metro lines in mountain city across numerous wide rivers and deep valleys, resulting in instability of high-pier bridge and insecurity of metro train under crosswind. Compared with the conditions of no-wind, crosswind triggers severer vibration of the dynamic system; compared with the short-pier viaduct, the high-pier viaduct has worse stability under crosswind. For these reasons, the running safety of the metro vehicle traveling on a high-pier viaduct under crosswind is analyzed to ensure the safe operation in metro lines in mountain cities. In this paper, a dynamic model of the metro vehicle-track-bridge system under crosswind is established, in which crosswind loads model considering the condition of wind zone are built. After that, the evaluation indices and the calculation parameters have been selected, moreover, the basic characteristics of the dynamic system with high-pier under crosswind are analyzed. On this basis, the response varies with vehicle speed and wind speed are calculated, then the corresponding safety zone is determined. The results indicate that, crosswind triggers drastic vibration to the metro vehicle and high-pier viaduct, which in turn causes running instability of the vehicle. The corresponding safety zone for metro vehicle traveling on the high-pier is proposed, and the metro traffic on the high-pier bridge under crosswind should not exceed the corresponding limited vehicle speed to ensure the running safety.

• Journal of the Optical Society of Korea
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• 제17권1호
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• pp.103-108
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• 2013

The operation of a Doppler wind LIDAR in a mobile environment is very sensitive to shocks and vibrations, which can cause critical failures such as misalignment of the optical path and damage to optical components. To be able to stabilize the LIDAR and to perform wind field measurements in motion, a shock absorption and vibration isolation system was designed and implemented. The performance of the vehicle-mounted Doppler wind LIDAR was tested in motion, first in a circular test route with a diameter of about 30 m and later in regular expressway traffic. The vibration isolation efficiency of the system was found to be higher than 82% in the main vibration area and shock dynamic deflection was smaller than maximal deflection of the isolator. The stability of the laser locking frequency in the same mobile environment before and after the vibration isolation system installation was also found to be greatly improved. The reliability of the vibration isolation system was confirmed by good results of the analysis of the LIDAR data, in particular the plane position indicator of the line of sight velocity and the wind profile.

• Wind and Structures
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• 제28권2호
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• pp.99-110
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• 2019

Vortex-Induced-Vibration (VIV) is one kind of the wind-induced vibrations, which may occur in the construction and operation period of bridges. This phenomenon can bring negative effects to the traffic safety or can cause bridge fatigue damage and should be eliminated or controlled within safe amplitudes.In the current VIV studies, one available mitigation countermeasure, the horizontal flow-isolating plate, shows satisfactory performance particularly in PI shaped bridge deck type. Details of the wind tunnel test are firstly presented to give an overall description of this appendage and its control effect. Then, the computational-fluid-dynamics(CFD) method is introduced to investigate the control mechanism, using two-dimensional Large-Eddy-Simulation to reproduce the VIV process. The Reynolds number of the cases involved in this paper ranges from $1{\times}10^5$ to $3{\times}10^5$, using the width of bridge deck as reference length. A field-filter technique and detailed analysis on wall pressure are used to give an intuitive demonstration of the changes brought by the horizontal flow-isolating plate. Results show that this aerodynamic appendage is equally effective in suppressing vertical and torsional VIV, indicating inspiring application prospect in similar PI shaped bridge decks.

• 한국항공운항학회지
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• 제30권4호
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• pp.132-144
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• 2022

In response to the recent surge in aviation demand, major airport and aviation authorities continue to make efforts to formulate arrival procedures that take into account efficient aircraft separation, noise and environmental issues related to carbon (CO₂) emissions. In order to ensure efficient traffic control and environmental issues, as a result, a new concept Trombone, Point Merge, etc. have been introduced and widely used. However, these new concept incisions are becoming a factor that hinders operational efficiency and stability due to the restricted domestic airspace such as military airspace and excessive constraints of altitude, speed, etc. which do not reflect the concept of continuous descent operation and eventually needs to be modified to make continuous descent operation as feasible as possible. We herewith analyze and propose the way of improving flight safety and efficiency in the arrival operation procedure by supplementary modification which consequently contribute to the aviation industry international competitiveness.

• 대한토목학회논문집
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• 제30권1D호
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• pp.61-70
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• 2010

현재의 경제성 평가는 교통량이 적어 편익이 적은 경우나 산악지형과 같이 터널 및 교량이 많은 도로와 같이 건설비가 많이 소요되는 사업의 경우, 기존의 비용편익분석으로는 타당성이 낮게 평가되는 경향이 있다. 그러나 이러한 사업도 생활환경의 개선, 방재기능의 강화, 격지지역의 민생안정, 양호한 경관 형성 등의 효과를 고려하면, 이들 사업은 타당한 사업으로 평가 될 수 있다. 본 논문에서는 현재 경제성 분석에서 계량화하여 반영하지 못하고 있는 도로사업으로 인하여 발생 가능한 파급효과에 대해 화폐가치화하기 위한 방법론 및 절차를 제시하고 실제 도로 건설사업을 대상으로 분석을 수행하였다.

• Journal of Information Processing Systems
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• 제19권5호
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• pp.590-601
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• 2023

University books are an important information resource. University book resources can be shared not only in the traditional paper form, but also electronic form under the background of the Internet. In order to better manage the sharing of electronic book resources in universities, this study put forward three resource sharing strategies: centralized sharing strategy, distributed sharing strategy, and centralized-distributed sharing strategy by analyzing the combined development of books and the Internet as well as the significance and development of book resource sharing. The centralized sharing strategy, however simple, was difficult to handle large traffic; while the resource nodes were independent and self-consistent, the distributed sharing strategy was not easy to find and had a high repetition rate. Combining the advantages of both strategies, the centralized-distributed sharing strategy was more suitable for the heterogeneous form of university book sharing. Finally, a teaching resources sharing platform for university libraries was designed based on the strategy of centralized and distributed sharing, and three interfaces including platform login, resource search, and resource release were displayed. The results of the simulated comparison experiment showed that centralized and distributed sharing strategies had limitations in resource searching and had low efficiencies; the efficiency of the centralized strategy reduced with an increase in search subjects; however, the centralized-distributed sharing strategy was able to search more resources efficiently and main stability.

• 대한안전경영과학회지
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• 제25권4호
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• pp.105-115
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• 2023

The purpose of this study is to identify psychological anxiety factors related to firefighters' field activities and suggest improvement measures. To investigate the actual status of psychological anxiety factors, a survey was conducted on approximately 3,500 current firefighters, and the responses of 505 people who participated in the survey were analyzed. As a research method, frequency analysis and cross-analysis were conducted according to the general characteristics of the participants to determine the actual level of psychological anxiety in each work field and the results were analyzed. As a result of the analysis, it was statistically confirmed that firefighters feel a lot of psychological burden due to legal and institutional inadequacies during dispatch, return, or field activities, and frequent friction with civil servants is also a major cause of psychological anxiety. Therefore, based on the results of this study, it is proposed to establish a permanent legal support team in each city and province, designate and operate a hospital dedicated to psychological treatment, and establish a special provision for traffic accidents during the return of fire trucks so that firefighters can concentrate on their duties without psychological anxiety. do.