• 한국산학기술학회논문지
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• 제15권5호
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• pp.3240-3250
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• 2014

본 연구는 개인들의 통행수단으로서 자동차 선택에 개인수준 및 도시특성, 도시형태의 세 가지 측면에서의 상관관계를 도출하는 것을 목적으로 한다. 본 연구에서는 자동차 이용을 감소시키는 도시특성 및 도시형태의 주요 요소로 5Ds를 중심으로 접근했다. 이러한 분석을 위해서 2005년 인구주택총조사자료 중 2%수준의 Micro Data내의 개인속성과 개인의 통행데이터 그리고 각 도시에서 제공하는 도시별 통계 데이터 등을 바탕으로 한국에 있는 도시 75개 도시와 그 거주자들을 대상으로 HGLM을 이용하여 분석하였다. 분석결과, 자동차 이용감소에 효과적인 도시특성 및 도시형태요소 분석을 위해서 개인수준의 통제는 반드시 필요하고, 5Ds는 대체로 자동차 이용 감소에 의미있는 관계를 보였으나 서구도시들에서 잘 알려진 자동차 이용 감소 요소인 Density와 Diversity는 한국의 도시에서는 상대적으로 큰 효과를 보이지 않는 사실을 도출할 수 있었다.

• Advances in aircraft and spacecraft science
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• 제10권6호
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• pp.495-519
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• 2023

The drone serves the customers not served by vans. At the same time, considering the safety, policy and terrain as well as the need to replace the battery, the drone needs to be transported by truck to the identified station along with the parcel. From each such station, the drone serves a subset of customers according to a direct assignment pattern, i.e., every time the drone is launched, it serves one demand node and returns to the station to collect another parcel. Similarly, the truck is used to transport the drone and cargo between stations. This is somewhat different from the research of other scholars. In terms of the joint distribution of the drone and road vehicle, most scholars will choose the combination of two transportation tools, while we use three. The drone and vans are responsible for distribution services, and the trucks are responsible for transporting the goods and drone to the station. The goal is to optimize the total delivery cost which includes the transportation costs for the vans and the delivery cost for the drone. A fixed cost is also considered for each drone parking site corresponding to the cost of positioning the drone and using the drone station. A discrete optimization model is presented for the problem in addition to a two-phase heuristic algorithm. The results of a series of computational tests performed to assess the applicability of the model and the efficiency of the heuristic are reported. The results obtained show that nearly 10% of the cost can be saved by combining the traditional delivery mode with the use of a drone and drone stations.

• 한국ITS학회 논문지
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• 제5권1호
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• pp.21-30
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• 2006

중앙버스전용차로제가 도입됨에 따라 서울의 도로환경은 단기간에 급격하게 변하였으며, 이러한 급격한 변화에 미리 준비되지 못하였던 신호운영상의 문제점들이 경험되고 있다. 장 임계적인 문제점으로 중앙버스전용차로 설치구간 신호교차로에서 일반차량 좌회전 진행을 허용할 경우, 현재 우리나라가 규정하고 있는 차량 4색신호등의 한계로 인한 신호의 비효율적 운영이다. 중앙버스전용차로 설치구간 신호교차로에서 일반차량 좌회전의 현실적 운영방안 마련이 필요하다. 본 연구는 중앙차로전용신호의 도입을 준비하기 위하여 교통관제센터의 신호운영모드별 선행좌회전 및 후행좌회전 운영방안을 검토하고, 각 운영방안 별 Signal Map 구성방안을 점검한다. Signal Map 작성방안을 검토한 결과 기존의 신호제어 장비에 추가의 신호등기신호보드를 활용하는 방법으로 제안된 방법의 현장 적용이 용이한 것으로 확인되었다.

• Steel and Composite Structures
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• 제49권2호
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• pp.215-230
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• 2023

Cable-girder anchorage joint is the critical part of cable-supported bridges. Tensile-plate anchorage (TPA) is one of the most commonly used types of cable-girder anchorage joints in steel girder cable-supported bridges. In recent years, it has been proposed by bridge designers to apply TPA to concrete girder cable-supported bridges to form composite cable-girder anchorage joint (CCGAJ). In this paper, the mechanical performance of CCGAJ under tensile force is studied through experimental and numerical analyses. Firstly, the effects of the external prestressing (EP) and the bearing plate (BP) on the mechanical performance of CCGAJ were investigated through three tests. Then, finite element model was established for parametrical study, and was verified by the experimental results. Then, the effects of shear connector forms, EP, BP, vertical rebar rate, and perforated rebar rate on the tensile capacity of CCGAJ were investigated through numerical analyses. The results show that the tensile capacity of CCGAJ depends on the first row of PR. The failure mode of CCGAJ using headed stud connectors is to form a shear failure surface at the end of the studs while the failure mode using PBLs is similar to the bending of a deep girder. Finally, based on the strut-and-tie model (STM), a calculation method for CCGAJ tensile capacity was proposed, which has a high accuracy and can be used to calculate the tensile capacity of CCGAJ.

• International Journal of Concrete Structures and Materials
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• 제8권1호
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• pp.43-59
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• 2014

Many bridges are subject to lateral damage for their girders due to impact by over-height vehicles collision. In this study, the optimum configurations of carbon fiber reinforced polymers (CFRP) laminates were investigated to repair the laterally damaged prestressed concrete (PS) bridge girders. Experimental and analytical investigations were conducted to study the flexural behavior of 13 half-scale AASHTO type II PS girders under both static and fatigue loading. Lateral impact damage due to vehicle collision was simulated by sawing through the concrete of the bottom flange and slicing through one of the prestressing strands. The damaged concrete was repaired and CFRP systems (longitudinal soffit laminates and evenly spaced transverse U-wraps) were applied to restore the original flexural capacity and mitigate debonding of soffit CFRP longitudinal laminates. In addition to the static load tests for ten girders, three more girders were tested under fatigue loading cycles to investigate the behavior under simulated traffic conditions. Measurements of the applied load, the deflection at five different locations, strains along the cross-section height at mid-span, and multiple strains longitudinally along the bottom soffit were recorded. The study investigated and recommended the proper CFRP repair design in terms of the CFRP longitudinal layers and U-wrapping spacing to obtain flexural capacity improvement and desired failure modes for the repaired girders. Test results showed that with proper detailing, CFRP systems can be designed to restore the lost flexural capacity, sustain the fatigue load cycles, and maintain the desired failure mode.

• 한국생산제조학회지
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• 제26권4호
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• pp.395-401
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• 2017

Energy absorption capabilities and failure modes of circular tubes made of glass/epoxy with two trigger mechanisms were evaluated. Three types of glass/epoxy tubes were fabricated using a hand lay-up method with unidirectional and woven fabric prepregs tapes, and a filament winding method. The one end of the fabricated tubes was machined for the bevel trigger and tulip trigger. Then, crush tests were conducted at 10 mm/min loading speed, wherein the glass/epoxy tubes were crushed by a brittle fracturing mode combined with fragmentation and lamina-splaying modes. The UD glass/epoxy tubes with a bevel trigger and the filament winded tubes with a tulip trigger showed the maximum and minimum specific energy absorptions, respectively, with a difference of 9.3%. The tube with a tulip trigger exhibited a maximum reduction of 5.7% in the initial peak load; the tube with a bevel trigger showed a maximum increase of 2.9% in the specific energy absorption.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.784-793
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• 2010

바이모달트램은 '저탄소 녹생성장' 이라는 국가 교통정책 패러다임에 따라 향후 대중교통체계에서 중요한 교통수단으로 기대된다. 최근 바이모달트램을 도입하기 위해 여러 지자체에서 검토가 이루어지고 있으나 바이모달트램 서비스 수준에 따른 시설 및 운영요건에 대한 도입 매뉴얼이 없는 것이 현실이다. 본 논문에서는 바이모달트램의 도입수준은 저급, 중급, 고급의 3가지로 구분을 하였으며 시설수준과 운영수준을 기준으로 하여 세부요소별 정의를 하였다. 본 연구는 신교통 수단인 바이모달트램을 도입하려는 지자체에 바이모달트램 도입수준에 따른 시설 및 운영요건을 고려하는데 도움을 줄 것으로 기대된다.

• 센서학회지
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• 제21권3호
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• pp.198-203
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• 2012

In this paper, the driving information system of the bicycle has been studied by using the 3-axis acceleration sensor. The sensor module composed of 3-axis acceleration sensor and MCU(Microcontroller Unit) was mounted onto the handle of bicycle and the experiments were conducted on the flatland, uphill and downhill of bicycle road. Three axis acceleration values were converted to the pitch and roll angles, then four major compensation methods have been applied to achieve meaningful data for driving information system. The experimental results of pitch angles showed 2.46, -1.26, 7.79 degrees in case of flatland, uphill, downhill, respectively. When the steering handle turned to the left direction, roll angles showed -29.35, -41.67, -36.98 degrees at each road condition. With the right-turn, roll angles presented 20.05, 33.75, 24.44 degrees in case of flatland, uphill, and downhill, respectively. The pitch angle has been increased more than 40 degrees at stop mode. By using the change of pitch and roll angles, we could obtain the driving information system of bicycle successfully.

• Geomechanics and Engineering
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• 제38권3호
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• pp.275-284
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• 2024

This paper aims to explore the evolution of the pullout behavior of geocell reinforcement insights from three-dimensional numerical studies. Initially, a developed model was validated with the model test results. The horizontal displacement of geocells and infill sand and the passive resistance transmission in the geocell layer were analyzed deeply to explore the evolution of geocell pullout behavior. The results reveal that the pullout behavior of geocell reinforcement is the pattern of progressive deformation. The geocell pockets are gradually mobilized to resist the pullout force. The vertical walls provide passive pressure, which is the main contributor to the pullout force. Hence, even if the frontal displacement (FD) is up to 90m mm, only half of the pockets are mobilized. Furthermore, the parametric studies, orthogonal analysis, and the building of the predicted model were also carried out to quantitative the geocell pullout behavior. The weights of influencing factors were ranked. Ones can calculate the pullout force accurately by inputting the aspect ratio, geocell modulus, embedded length, frontal displacement, and normal stress.

• 한국항만경제학회지
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• 제37권4호
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• pp.13-31
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• 2021

2011년 한-유럽 FTA 체결 이후 두 지역의 거래액은 증가일로에 있으며 전체 시장은 지속적으로 확대되고 있다. 여러 운송수단을 이용하는 복합국제운송에 대한 관심이 늘어나며 기존의 해운운송 위주의 운송 방식에서 철도를 포함한 두 가지 이상의 운송수단을 사용하는 다중운송경로를 통한 운송이 확대되고 있다. COVID-19의 영향으로 2019년 세계 화물 시장이 타격을 받았는데 특히 해상 및 항공 노선의 급격한 제한에 기인하고 한국의 대유럽 수출도 감소하였다. 이러한 영향에도 2020년 CRE(China Railway Express) 화물 열차의 총 수는 2016년 대비 7.3배 증가한 12,406개 노선으로 전년 대비 50% 증가하였다. 철도를 이용한 육상기반의 화물운송에 대한 연구는 꾸준히 있어 왔으나 한국과 유럽의 운송노선에 대한 연구는 TSR(Trans Siberian Railway), 수에즈 해운(Suez Shipping), 기존 TCR(Trans China Railway) 노선에 국한되었다. 본 논문은 중국에서의 일대일로 구상에 따라 최근 변화를 겪고있는 실크로드의 핵심에 초점을 맞추어 중국-유럽 화물열차(CRE)를 대상으로 연구를 진행하였다. Fuzzy-AHP는 한국에서 유럽으로 가는 국제 복합항로 선정 시 요인의 우선순위를 결정하는데 사용하였으며 중국과 한국의 전문가 설문조사를 통해 결과를 도출하였다. 요인 선정 후 TOPSIS 방법을 적용하여 계획된 3개의 경로를 순위화하였다. 그 결과 총비용, 총시간, 서비스 신뢰도가 CRE 기반 복합운송을 선택할 때 의사결정자가 고려하는 요소로 나타났다. 또한, 주요 3개 복합운송노선에서 Route 1(인천-대련-만주-함부르크) 노선이 최적 노선이고 Route 2(인천-리차오-얼롄하오터-함부르크)와 Route 3(인천-롄윈강-시안-함부르크) 순서로 나타났다.