• 대한교통학회지
• /
• 제32권2호
• /
• pp.170-178
• /
• 2014

지금까지 교통사고발생과 기하구조와의 관계파악을 위한 모형정립에 관한 연구가 많이 이루어져 왔다. 이러한 연구들은 도로선형, 기하구조의 개선 혹은 위험구간 선정 등에 사용되어 교통사고 건수 및 사고심각도를 줄이는데 기여를 하여왔다. 하지만, 모형정립에 사용되었던 변수들은 자료수집 부족 등의 이유로 변수 혹은 대상구간이 가지고 있는 기하구조의 비동질성을 고려하지 못한 측면이 있었으며, 이는 모형 정립시 계수의 표준오차값이 과소 추정되어 모형전체의 신뢰성에 영향을 미쳐왔다. 따라서, 이번 연구에서는 사용되는 변수의 비동질성 고려가 모형의 결과에 미치는 영향을 알아봄으로써, 비동질성의 중요성을 파악하고자 하는데 목적이 있다. 그 결과, 모든 기하구조에 대한 비동질성을 고려하지는 못하였으나, 몇몇 사용된 기하구조 변수들의 경우, 의미 있는 결과가 도출되었다.

• 대한원격탐사학회지
• /
• 제40권1호
• /
• pp.57-69
• /
• 2024

Crop classification plays a vitalrole in monitoring agricultural landscapes and enhancing food production. In this study, we explore the effectiveness of Long Short-Term Memory (LSTM) models for crop classification, focusing on distinguishing between apple and rice crops. The aim wasto overcome the challenges associatedwith finding phenology-based classification thresholds by utilizing LSTM to capture the entire Normalized Difference Vegetation Index (NDVI)trend. Our methodology involvestraining the LSTM model using a reference site and applying it to three separate three test sites. Firstly, we generated 25 NDVI imagesfrom the Sentinel-2A data. Aftersegmenting study areas, we calculated the mean NDVI values for each segment. For the reference area, employed a training approach utilizing the NDVI trend line. This trend line served as the basis for training our crop classification model. Following the training phase, we applied the trained model to three separate test sites. The results demonstrated a high overall accuracy of 0.92 and a kappa coefficient of 0.85 for the reference site. The overall accuracies for the test sites were also favorable, ranging from 0.88 to 0.92, indicating successful classification outcomes. We also found that certain phenological metrics can be less effective in crop classification therefore limitations of relying solely on phenological map thresholds and emphasizes the challenges in detecting phenology in real-time, particularly in the early stages of crops. Our study demonstrates the potential of LSTM models in crop classification tasks, showcasing their ability to capture temporal dependencies and analyze timeseriesremote sensing data.While limitations exist in capturing specific phenological events, the integration of alternative approaches holds promise for enhancing classification accuracy. By leveraging advanced techniques and considering the specific challenges of agricultural landscapes, we can continue to refine crop classification models and support agricultural management practices.

• 대한교통학회지
• /
• 제33권3호
• /
• pp.304-314
• /
• 2015

대도시권에서 지하철의 우회는 승용차 통행에 비해 지하철의 경쟁력을 떨어뜨리는 요인으로 지적되어 왔다. 그러나 새로운 지하철 시스템을 계획하거나, 기존의 운행 노선을 개선할 때 다른 가치들 (영업이익, 수요, 노선의 균등 분배 등)과의 관계에서 우회에 대한 최소기준 정도만 존재할 뿐 다른 가치들과의 가중에 대한 기준이 모호한 실정이다. 이 연구는 우회의 개념을 사용하여 수도권 지하철의 거리 효율 평가 모형을 다루고 있다. 연구의 목적은 지금까지의 우회율과 관련된 선행연구들에 대해 요약을 하고 새로운 거리 효율 평가 모형을 만들어보며, 이 모형을 수도권 지하철 3호선에 적용하는데 있다. 주요 결과는 두 가지로 나눠볼 수 있다. 첫째, 가장 크게 우회하는 OD는 '대치'역부터 '압구정'역까지였으며 우회계수는 1.93으로 나타났다. 이는 도로의 네트워크보다 약 1.93배 더 길게 우회하는 것을 의미한다. 한편, 수도권 지하철 3호선을 전체적으로 분석을 해본 결과, 도로의 네트워크보다 평균적으로 약 20% 더 우회하는 것으로 나타났다.

• 대한토목학회논문집
• /
• 제41권1호
• /
• pp.75-83
• /
• 2021

지나친 도시화로 인한 차량증가로 도시교통 문제가 사회문제로 인식되고 있고 이로 인해 효과적인 도로계획과 설계는 더욱 중요하게 되었다, 이에 따라 기존 도로를 확장하거나 새로운 도로를 건설할 때 도로의 교통량 산정에 필요한 기준과 방법을 도로용량편람으로 제정하여 운영하고 있다. 하지만 철도 노선에는 이러한 중요성에 불구하고 체계적인 교통량 산정기준이나 방법이 없었다. 따라서 본 연구에서는 철도의 경쟁력 강화를 위해 철도에도 노선용량이란 개념을 도입하여 명확한 철도 노선용량의 산정기준과 방법을 제시 하였다. 그 결과를 바탕으로 국내 철도의 주요 선구별 노선용량을 산정하였다, 이에 따라 본 연구에서 제시한 노선용량 산정방법을 적용하면, 기존의 철도 노선 및 새롭게 확대되는 신규 노선의 용량에 대한 적정한 투자와 설계가 계획단계에서부터 이루어 질 수 있도록 체계적인 기준을 제공할 수 있게 되었으며, 향후 철도 운행효율성 향상에도 도움을 줄 수 있을 것으로 기대한다.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제6권4호
• /
• pp.1130-1147
• /
• 2014

Large size ships have a very flexible construction resulting in low resonance frequencies of the structural eigen-modes. This feature increases the dynamic response of the structure on short period waves (springing) and on impulsive wave loads (whipping). This dynamic response in its turn increases both the fatigue damage and the ultimate load on the structure; these aspects illustrate the importance of including the dynamic response into the design loads for these ship types. Experiments have been carried out using a segmented scaled model of a container ship in a Seakeeping Basin. This paper describes the development of the model for these experiments; the choice was made to divide the hull into six rigid segments connected with a flexible beam. In order to model the typical feature of the open structure of the containership that the shear center is well below the keel line of the vessel, the beam was built into the model as low as possible. The model was instrumented with accelerometers and rotation rate gyroscopes on each segment, relative wave height meters and pressure gauges in the bow area. The beam was instrumented with strain gauges to measure the internal loads at the position of each of the cuts. Experiments have been carried out in regular waves at different amplitudes for the same wave period and in long crested irregular waves for a matrix of wave heights and periods. The results of the experiments are compared to results of calculations with a linear model based on potential flow theory that includes the effects of the flexural modes. Some of the tests were repeated with additional links between the segments to increase the model rigidity by several orders of magnitude, in order to compare the loads between a rigid and a flexible model.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
• /
• pp.448-448
• /
• 2000

This paper deals with dynamic behaviour analysis for pipeline inspection gauge (PIG) flow control in natural gas pipeline. The dynamic behaviour of the PIG is depending on the different Pressure between the rear and nose parts, which is generated by injected gas flow behind PIG's tail and expelled gas flow in front of its nose. To analyze the dynamic behaviour characteristics such as gas flow in pipeline, and the PIG's position and velocity, mathematical model is derived as two types of a nonlinear hyperbolic partial differential equation for unsteady flow analysis of the PIG driving and expelled gas, and nonhomogeneous differential equation for dynamic analysis of PIG. The nonlinear equation is solved by method of characteristics (MOC) with the regular rectangular grid under appropriate initial and boundary conditions. The Runge-Kuta method is used when we solve the steady flow equations to get initial flow values and the dynamic equation of PIG. The gas upstream and downstream of PIG are divided into a number of elements of equal length. The sampling time and distance are chosen under Courant-Friedrich-Lewy (CFL) restriction. The simulation is performed with a pipeline segment in the Korea Gas Corporation (KOGAS) low pressure system, Ueijungboo-Sangye line. The simulation results show us that the derived mathematical model and the proposed computational scheme are effective for estimating the position and velocity of PIG with different operational conditions of pipeline.

• Structural Engineering and Mechanics
• /
• 제56권2호
• /
• pp.169-188
• /
• 2015

There are two types of nonlinear analysis methods for building frameworks depending on the method of modeling the plastification of members including lumped plasticity and distributed plasticity. The lumped plasticity method assumes that plasticity is concentrated at a zero-length plastic hinge section at the ends of the elements. The distributed plasticity method discretizes the structural members into many line segments, and further subdivides the cross-section of each segment into a number of finite elements. When a reinforced concrete member experiences inelastic deformations, cracks tend to spread form the joint interface resulting in a curvature distribution. The program IDARC includes a spread plasticity formulation to capture the variation of the section flexibility, and combine them to determine the element stiffness matrix. In this formulation, the flexibility distribution in the structural elements is assumed to be the linear. The main objective of this study is to evaluate the accuracy of linear flexibility distribution assumed in the spread inelasticity model. For this purpose, nonlinear analysis of two reinforced concrete frames is carried out and the linear flexibility models used in the elements are compared with the real ones. It is shown that the linear flexibility distribution is incorrect assumption in cases of significant gravity load effects and can be lead to incorrect nonlinear responses in some situations.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집B
• /
• pp.241-246
• /
• 2001

This paper introduces modeling and solution for the dynamics of pipeline inspection gauge (PIG) flow in natural gas pipeline. Without of bypass flow, the dynamic behavior of the PIG depends on the different pressure between the rear and nose parts, which is generated by injected gas flow behind the tail of the PIG and expelled gas flow in front of its nose. With bypass flow, the PIG dynamics also depends on the amount of bypass flow across its body. The mathematical model are derived for unsteady compressible flow of the PIG driving and expelled gas, and for dynamics of the PIG. The bypass flow is assumed to be incompressible with the condition of its Mach number smaller than 0.45. The method of characteristic (MOC) and the Runge-Kutta method are used to solve the system governing equations. The simulation is performed with a pipeline segment in the Korea Gas Corporation (KOGAS) low pressure system, Ueijungboo-Sangye line. The simulation results show that the derived mathematical model and the proposed solution are effective for estimation the dynamics of the PIG with and without bypass flow under given operational condition.

• International Journal of Internet, Broadcasting and Communication
• /
• 제7권1호
• /
• pp.10-14
• /
• 2015

Video Content owners seek to squeeze the maximum amount of revenue from their assets via distribution into more territories. Digital Cinema Package(DCP), trusted solution to distribute protected content to theaters, caters to relatively small user base, which limits revenue. With the growth of the Internet & other digital media, the economics of media content has changed dramatically. Security remains main concern to deliver content to millions of consumers using intelligent digital display devices like Tablets, Smartphones, Smart TVs, Desktop & Laptop. By making the video content available to this segment securely, content owners will benefit from increased revenue. Through this paper we propose Open Source HomeDCP model to distribute the content to home users for offline viewing. We propose to include other open source CODEC than JPEG2000/MPEG2, which are specifically designed for theatrical performance. Final image size will be further reduced considering the display device resolution where video will be finally played. Key Delivery Message(KDM) system to be altered to suit new devices. This will be a big boost to Content Economy as content owners would be able to distribute the content securely to the wider audience & ensure more revenue.

• Journal of Mechanical Science and Technology
• /
• 제17권9호
• /
• pp.1349-1357
• /
• 2003

This paper deals with verification of the theoretical model for dynamic behavior of Pipeline Inspection Gauge (PIG) traveling through high pressure natural gas pipeline. The dynamic behavior of the PIG depends on the differential pressure across its body. This differential pressure is generated by injected gas flow behind the tail of the PIG and expelled gas flow in front of its nose. To analyze the dynamic behavior characteristics such as gas flow in pipeline, and the PIG position and velocity, not only the mathematical models are derived, but also the theoretical models must be certified by actual pigging experiment. But there is not any found results of research on the experimental certification for dynamic behavior of the PIG. The reason is why the fabrication of the PIG as well as, a field application are very difficult. In this research, the effectiveness of the introduced solution using the method of characteristics (MOC) was certified through field application. In-line inspection tool, 30" geometry PIG, was fabricated and actual pigging was carried out at the pipeline segment in Korea Gas Corporation (KOGAS) high pressure system, Incheon LT (LNG Terminal) -Namdong GS (Governor Station) line. Pigging is fulfilled successfully. Comparison of simulation results with experimental results show that the derived mathematical models and the proposed computational schemes are effective for predicting the position and velocity of the PIG with a given operational conditions of pipeline.