• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.897-900
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• 2000

본 논문에서는 종방향 충돌경보 및 회피시스템(FCWA ; forward collision warning and avoidance)의 일환으로 가변적인 경사도를 가지는 고속도로상의 차선, 차량, 그리고 도로의 곡률을 효과적으로 검출할 수 있는 알고리듬을 제안하였다. 먼저 2D 영상좌표계에 나타나는 투영효과를 제거하기 위한 역투영(IPM; inverse perspective mapping)기법을 소개하였다. 또한 IPM과 필터로부터 차선과 차량을 효과적으로 검출할 수 있는 알고리듬을 소개하였다. 마지막으로 경사가 있는 실제도로영상에 대한 IMP의 수정된 파라미터 보정에 대한 개념 및 실제도로의 곡률 검출을 위한 기하학적 함수 추정기법을 설명하였다 실험결과 제안한 알고리듬이 실제도로영상에서 차선, 차량, 그리고 곡률의 검출에 효과적임을 확인할 수 있었다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.418-419
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• 2008

관로에 케이블을 포설할 때에는 최대포설장력(Maximum Pulling Tension Factors)과 허용측압(Sidewall Bearing Pressure)이 고려되어야 한다. 최대포설장력은 케이블의 무게와 관로의 마찰계수에 의해 계산이 되고 관로의 경간에 의해 변화하게 된다. 측압은 관로의 곡률반경, 포설장력, 케이블 무게 등과 직접 관련이 있다. 관로의 곡률반경은 현장에서 도로의 길이와 현의길이, 호의 높이 등을 측정하여 구하기도 하고 도면상에서 계산에 의해 구하기도 한다. 곡률반경과 포설장력, 측압의 관계성을 비교해 보면 포설장력은 곡률반경의 영향을 거의 받지 않지만 측압은 곡률반경의 영향을 크게 받는다. 허용측압이상의 측압이 굴곡부에서 관로와 케이블사이에 발생하면 관로와 케이블이 손상되기 때문에 관로 설계시에는 측압을 반드시 고려하여야 된다.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.924-926
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• 2017

본 논문에서는 좁고 곡률이 큰 도로에서의 자율 주행을 위한 AVM 시스템 기반의 알고리즘을 제안한다. 기존의 전방을 주시하는 모노/스테레오 카메라를 이용한 차선 인식 방법을 이용한 자율주행 알고리즘은 모노/스테레오 카메라의 제한된 FOV (Field of View)로 인해 좁고 곡률이 큰 도로에서의 자율 주행에 한계가 있다. 제안하는 알고리즘은 AVM 시스템을 기반으로 하여 이 한계를 극복하고자 한다. AVM 시스템에서 얻은 영상을 차선의 색상 정보를 이용해 차선의 영역을 이진화 한다. 이진화 영상으로부터, 차량의 뒷바퀴 주변의 관심영역을 시작으로 재귀적 탐색법을 이용하여 좌, 우 차선을 검출한다. 검출된 좌, 우 차선의 중앙선을 차량의 경로로 삼고 조향각을 산출해 낸다. 제한하는 알고리즘을 실제 차량에 적용시킨 실험을 수행하였고, 운전면허 시험장의 코스를 차선의 이탈없이 주행 가능함을 실험적으로 확인하였다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.2
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• pp.52-62
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• 2013

Design Hourly Factor(DHF) is defined as the ratio of design hourly volume(DHV) to Average Annual Daily Traffic(AADT). Generally DHV used the 30th rank hourly volume. But this case DHV is affected by holiday volumes so the road is at risk for overdesigning. Computing K factor is available for counting 8,760 hour traffic volume, but it is impossible except permanent traffic counts. This study applied three method to make DHF, using 30th rank hourly volume to make DHF(method 1), using peak hour volume to make DHF(method 2). Another way to make DHF, rank hourly volumes ordered descending connect a curve smoothly to find the point which changes drastic(method 3). That point is design hour, thus design hourly factor is able to be computed. In addition road classified 3 type for national highway using factor analysis and cluster analysis, so we can analyze the characteristic of DHF by road type. DHF which was used method 1 is the largest at any other method. There is no difference in DHF by road type at method 2. This result shows for this reason because peak hour is hard to describe the characteristic of hourly volume change. DHF which was used method 3 is similar to HCM except recreation road but 118th rank hourly volume is appropriate.

• Journal of Auto-vehicle Safety Association
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• v.4 no.1
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• pp.27-32
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• 2012

Recently, in order to reduce traffic accident related fatalities, increasing number of studies are conducted regarding the vehicle safety enhancement devices. But very few studies about test procedures and requirements for vehicle safety systems are being carried out. Since BSD, as one of the most important safety features, is installed on a new vehicle, its performance test method has to be evaluated. Independent factors irrelevant to the device types including collision position, vehicle speed and closing speed are used to calculate test distance away from the current vehicle. Effect of roadway geometry as radius of curvature is introduced to propose possible misjudgement of following vehicle as adjacent one. The study results would be utilized to enhance the test procedure of BSD performance.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.2
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• pp.61-76
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• 2021

As the number of existing road tunnels increases every year, collapse and floor heaving accidents occur frequently during construction. The collapse among tunnel accidents dominates, so that studies related to the floor heaving are relatively insufficient. Accordingly, many studies to reinforce the lower part of the tunnel have been conducted, but the analysis on the effect of the curvature of the tunnel floor is insufficient. Therefore, in this study, the effects of the upper analysis area height and the coefficient of lateral earth pressure of the tunnel located on a tuff deterioration zone with a large rock cover, as well as the floor curvature, were examined through sensitivity analysis. As a result of the analysis, it turned out that the overall stability of the tunnel increases as the floor curvature increases, the coefficient of lateral earth pressure decreases, and the upper analysis region increases.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.3
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• pp.42-55
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• 2021

In this study, the effect of nozzle performance according to the selection of the center line equation. Three of S-type nozzles and three of double S-type nozzles were designed using the curve equation and design parameters, and the nozzle shielding performance was evaluated using the shielding ratio definition. In order to analyze the internal flow of the nozzle, the characteristics of the velocity distribution and pressure distribution were studied, and the nozzle performance was evaluated through the total thrust ratio(f) and the nozzle insulation efficiency coefficient(η). On the other hand, the centerline with a sharply change in curvature at the entrance has a low nozzle performance and a high shielding rate. The double S-type nozzle is excellent nozzle performance and shielding rate by using a smooth centerline at the first curvature.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.2
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• pp.107-118
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• 2021

Due to the acceleration of road construction, the number and extension of tunnels are increasing every year. A lot of research has been done on the collapse of tunnels, but research on the invert heaving is insufficient. Therefore, in this study, a sensitivity analysis was performed using a geotechnical general-purpose program to analyze the effect of the invert curvature of a tunnel excavated on the soft ground. As a result, it was quantitatively confirmed that the stability of a tunnel was increased as the curvature of the tunnel invert was increased so that the safety factor was calculated to be large regardless of the ground conditions and the thickness of the support. In addition, it was confirmed that the stability of the tunnel was increased by reducing the convergence of the tunnel and the maximum bending stress supported by shotcrete. Therefore, when a tunnel is excavated on soft ground, it is believed that applying a curvature to the invert will increase the stability of the tunnel.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.1 s.47
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• pp.41-49
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• 2006

Through the 1982 Urahawa-ohi and the 1995 Kobe earthquakes, a number of bridge columns were observed to develop a flexural-shear failure due to the bond slip as a consequence of premature termination of the column longitudinal reinforcement. Because the seismic behavior of RC bridge piers is largely dependent on the performance of the plastic hinge legion of RC bridge piers, it is desirable that the seismic capacity of RC bridge pier is to evaluate as a curvature ductility. The provision for the lap splice of longitudinal steel was not specified in KHBDS(Korea Highway Bridge Design Specification) before the implementation of 1992 seismic design code, but the lap splice of not more than 50%, longitudinal reinforcement was newly allowed in the 2005 version of the KHBDS. The objective of this research is to investigate the distribution and ductility of the curvature of RC bridge column with the lap splice of longitudinal reinforcement in the plastic hinge legion. Six (6) specimens were made in 600 mm diameter with an aspect ratio of 2.5 or 3.5. These piers were cyclically subjected to the quasi-static loads with the uniform axial load of $P=0.1f_{ck}A_g$. According to the slip failure of longitudinal steels of the lap spliced specimen by cyclic loads, the curvatures of the lower and upper parts of the lap spliced region were bigger and smaller than the corresponding paris of the specimen without a lap splice, respectively. Therefore, the damage of the lap spliced test column was concentrated almost on the lower part of the lap spliced region, that appeared io be failed in flexure.

• Journal of computational fluids engineering
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• v.1 no.1
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• pp.35-46
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• 1996

원심형 임펠러 내부 유로등 큰 곡률을 수반하는 터보기계 요소의 유동해석을 위한 계산코드를 개발하였다. 이 코드에서는 곡선좌표계에 유도된 3차원 비압축성 Navier-Stokes의 운동 방정식을 SMAC 음해법으로 푼다. 이 코드를 이용하여 유로의 단면이 정사각형이고 90도로 굽은 덕트내부의 층류 입구유동을 해석하고, 굽은 관 특유의 유동현상을 수치모사하였다 또한 곡관부 입구에서 충분히 발달한 유동, 또는 발달중인 유동이 유입될 경우에 이것이 곡관부 내부의 유동에 미치는 영향을 상·하류의 계산영역이 서로 다를 몇몇 유동장에 대하여 조사하고, 본 계산에서 얻어진 결과와 실형결과와의 비교로 본 3차원 유동해석 코드의 유효성을 검토 하였다.