• 유통과학연구
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• 제21권9호
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• pp.93-102
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• 2023

Purpose: This study attempts to analyze the current status of the railway logistics business and to seek ways to improve it by using the business model as an analytical framework. It was intended to reflect practical implications that could be applied to the field, by dealing with issues at the industrial site related to each component in the business model. Research design, data and methodology: This study was conducted through literature review and field research. We analyzed academic papers and industrial reports on the development of the railway logistics industry and interviewed various stakeholders in the railway logistics industry. Results: This study determined the factors that could be eliminated, raised, reduced, or created from the customer and product perspective, infrastructure management perspective, and financial perspective. Conclusions: The growth of existing business can be achieved by lowering service prices, improving service quality, and securing large-scale transportation capacity. The additional transportation of high value goods and cold chain commodities will be promising business opportunities. Existing services can be provided to new customers (large pre-shippers, forwarding customers, etc.) in order to increase the size of sales Urban delivery services and comprehensive logistics services based on complex logistics centers may open an avenue for new market. A more timetable and track capacity need to be assigned to logistics, which significantly improve the flexibility and the competency of railway logistics.

• Advances in aircraft and spacecraft science
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• 제10권1호
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• pp.83-106
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• 2023

In this work, the static behavior of FGM macro and nano-plates under thermomechanical loading. Equilibrium equations are determined by using virtual work principle and local and non-local theory. The novelty of the current model is using a new displacement field with four variables and a warping function considering the effect of shear. Through this analysis, the considered sandwich FGM macro and nanoplates are a homogeneous core and P-FGM faces, homogeneous faces and an E-FGM core and finally P-FGM faces and an E-FGM core. The analytical solution is obtained by using Navier method. The model is verified with previous published works by other models and very close results are obtained within maximum 1% deviation. The numerical results are performed to present the influence of the various parameters such as, geometric ratios, material index as well as the scale parameters are investigated. The present model can be applicable for sandwich FG plates used in nuclear, aero-space, marine, civil and mechanical applications.

• 한국측량학회지
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• 제14권1호
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• pp.27-38
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• 1996

최근 GIS를 비롯한 각종 지형자료의 응용분야에서 기존의 종이지도가 지니는 제한된 축척 및 정보량 등의 경직성을 탈피한 수치지도의 제작은 시급한 당면 과제로 부각되고 있다. 본 연구에서는 수작업으로 처리되고 있는 편집도의 제작을 자동화하기 위한 방안으로 디지털 환경하에서의 일반화 기법에 대한 연구를 수행하였으며, 주된 연구대상으로는 일반화 알고리즘을 처리 형태별로 개발하여 프로그램화하고 이들 결과를 이용하여 컴퓨터 상에서 특정 지형지물에 대한 소축척지도의 자동제작을 구현하였다. 또한 GIS측면에서의 벡터 데이터로서 동일한 위상구조를 지니기 위한 일반화 전후의 데이터 분석을 토대로 처리형태별 우선 순위의 결정 및 오차량 산정을 실시하여 우리실정에 맞는 일반화의 데이터모델을 분석하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권5호
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• pp.1744-1760
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• 2021

Since correlation filter appeared in the field of object tracking, it plays an increasingly vital role due to its excellent performance. Although many sophisticated trackers have been successfully applied to track the object accurately, very few of them attaches importance to the scale and rotation estimation. In order to address the above limitation, we propose a novel method combined with Fourier-Mellin transform and confidence evaluation strategy for robust object tracking. In the first place, we construct a correlation filter to locate the target object precisely. Then, a log-polar technique is used in the Fourier-Mellin transform to cope with the rotation and scale changes. In order to achieve subpixel accuracy, we come up with an efficient surface fitting mechanism to obtain the optimal calculation result. In addition, we introduce a confidence evaluation strategy modeled on the output response, which can decrease the impact of image noise and perform as a criterion to evaluate the target model stability. Experimental experiments on OTB100 demonstrate that the proposed algorithm achieves superior capability in success plots and precision plots of OPE, which is 10.8% points and 8.6% points than those of KCF. Besides, our method performs favorably against the others in terms of SRE and TRE validation schemes, which shows the superiority of our proposed algorithm in scale and rotation evaluation.

• 자원환경지질
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• 제44권2호
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• pp.171-180
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• 2011

화강암, 사암, 편마암으로 구성된 21개 암석시료를 대상으로 열전도도를 측정하고, XRD 정량분석을 통해 구성광물의 조성을 파악하였으며, 구조모델 이용하여 석영 함량 및 광물입자의 크기가 암석의 유효열전도도에 미치는 영향을 분석하였다. 측정된 열전도도는 석영 함량과 높은 상관성을 보여 ($R^2=0.75$), 석영 함량으로부터 열전도도를 추정할 수 있는 선형회귀모형을 제시하였다. 화강암 및 변성암 일부 시료의 경우 유사한 석영 함량에도 불구하고 열전도도가 크게 다른 값을 보였는데, 이는 주로 광물업자의 크기 변화와 관련이 있는 것으로 나타났다. 구조모델을 통한 분석 결과 입자의 크기가 작은 경우 열전도도는 scries와 EMT모델의 중간 영역에 해당하는 값을 보이며, 입자가 커지면서 EMT모델, ME모델을 거쳐 Parallel모델에 근접하게 변화하였다. 이러한 열전달 구조모델의 변화는 입자의 크기에 따른 열전도도 변화가 3 mm 두께의 원반시편을 이용하는 실험 규모와 관련이 있음을 시사한다. 즉, 얇은 원반 시료를 이용하여 암석의 열전도도를 측정할 경우 규모효과에 의하여 실제 지반의 값보다 과대평가될 가능성이 높으며, 특히 광물 입자의 크기가 클수록 이러한 오차는 더 커질 것으로 예상된다. 따라서 지열과 관련된 다양한 해석 모델에서 실험실 측정값을 실제 현장규모에서의 대표값으로 사용할 경우 모델의 예측 신뢰도에 영향을 줄 수 있는 요인으로 작용할 수 있다.

• Structural Engineering and Mechanics
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• 제62권5호
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• pp.551-565
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• 2017

Based on the strain gradient theory (SGT), vibration analysis of an embedded micro cylindrical shell reinforced with agglomerated carbon nanotubes (CNTs) is investigated. The elastic medium is simulated by the orthotropic Pasternak foundation. The structure is subjected to magnetic field in the axial direction. For obtaining the equivalent material properties of structure and considering agglomeration effects, the Mori-Tanaka model is applied. The motion equations are derived on the basis of Mindlin cylindrical shell theory, energy method and Hamilton's principal. Differential quadrature method (DQM) is proposed to evaluate the frequency of system for different boundary conditions. The effects of different parameters such as CNTs volume percent, agglomeration of CNTs, elastic medium, magnetic field, boundary conditions, length to radius ratio and small scale parameter are shown on the frequency of the structure. The results indicate that the effect of CNTs agglomeration plays an important role in the frequency of system so that considering agglomeration leads to lower frequency. Furthermore, the frequency of structure increases with enhancing the small scale parameter.

• Structural Engineering and Mechanics
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• 제66권2호
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• pp.237-248
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• 2018

This study presents the investigation of wave dispersion characteristics of a magneto-electro-elastic functionally graded (MEE-FG) nanosize beam utilizing nonlocal strain gradient theory (NSGT). In this theory, a material length scale parameter is propounded to show the influence of strain gradient stress field, and likewise, a nonlocal parameter is nominated to emphasize on the importance of elastic stress field effects. The material properties of heterogeneous nanobeam are supposed to vary smoothly through the thickness direction based on power-law form. Applying Hamilton's principle, the nonlocal governing equations of MEE-FG nanobeam are derived. Furthermore, to derive the wave frequency, phase velocity and escape frequency of MEE-FG nanobeam, an analytical solution is employed. The validation procedure is performed by comparing the results of present model with results exhibited by previous papers. Results are rendered in the framework of an exact parametric study by changing various parameters such as wave number, nonlocal parameter, length scale parameter, gradient index, magnetic potential and electric voltage to show their influence on the wave frequency, phase velocity and escape frequency of MEE-FG nanobeams.

• 지질공학
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• 제25권4호
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• pp.439-447
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• 2015

In this study, specific sections vulnerable to debris flow damage were selected, and a complete enumeration survey was performed for the sections with debris flow hazards. Based on this, the characteristics of the sections with debris flow hazards and the current status of actions against debris flow were examined, and an efficient installation plan for a debris flow damage prevention method that is required in the future was suggested. The results indicated that in the Route 56 section where the residential density is relatively higher between the two model survey sections, facilities for debris flow damage reduction were insufficient compared to those in the Route 6 section which is a mountain area. It is thought that several sites require urgent preparation of a facility for debris flow damage reduction. In addition, a numerical analysis showed that for debris barriers installed as a debris flow damage prevention method, distributed installation of a number of small-scale barriers facilities within a valley part was more effective than single installation of a large-scale debris barrier at the lower part of a valley.

• Structural Engineering and Mechanics
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• 제71권6호
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• pp.669-682
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• 2019

We in this article study nonlinear thermal buckling of bi-directional functionally graded beams in the theoretical frameworks of nonlocal strain graded theory. To begin with, it is assumed that the effective material properties of beams vary continuously in both the thickness and width directions. Then, we utilize a higher-order shear deformation theory that includes a physical neutral surface to derive the size-dependent governing equations combining with the Hamilton's principle and the von $K{\acute{a}}rm{\acute{a}}n$ geometric nonlinearity. It should be pointed out that the established model, containing a nonlocal parameter and a strain gradient length scale parameter, can availably account for both the influence of nonlocal elastic stress field and the influence of strain gradient stress field. Subsequently, via using a easier group of initial asymptotic solutions, the corresponding analytical solution of thermal buckling of beams is obtained with the help of perturbation method. Finally, a parametric study is carried out in detail after validating the present analysis, especially for the effects of a nonlocal parameter, a strain gradient length scale parameter and the ratio of the two on the critical thermal buckling temperature of beams.

• 환경생물
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• 제35권1호
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• pp.13-20
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• 2017

본 연구는 대한민국 전역을 대상으로 국외에서 개발된 토양 온실가스 배출 모형인 DNDC 모형을 적용하여 논 토양에서 배출되는 $CO_2$를 추정하였다. 모형의 국내 적용성 평가를 위해서 2015년부터 2016년 경기도 지역 논 토양을 대상으로 폐쇄형 챔버를 이용해 $CO_2$ 배출량을 실측하고, 모형으로부터 산출된 추정값과 비교했다. DNDC 모형 검증결과 추정값과 관측값의 RMSE, ME, $r^2$이 각각 22.2, 0.28, 0.53으로 통계적으로 신뢰할 수 있었다. 전국 $CO_2$ 배출량 예측 결과, 연간 총 배출량은 $5,314kt\;CO_2-eq$이며 이는 전국 $CH_4$ 총 배출량의 77% 수준이었다. 행정구역별로는 전라도가 가장 많은 배출량을 보였으며, 논의 면적이 많을수록 총 배출량이 높았다. 국토의 단위면적당 $CO_2$ 배출량은 $2.2{\sim}10.0t\;CO_2-eq\;ha^{-1}year^{-1}$ 범위에 있었으며, 평균값은 $4.3t\;CO_2-eq\;ha^{-1}year^{-1}$ 이었다. 지역적으로는 한반도 중부지역 보다 남부지역에서 단위면적당 배출량이 더 높게 나타났다. 본 연구를 통해서, DNDC 모형은 국내 논 토양에서 배출되는 $CO_2$ 발생량을 유의하게 모의한 것으로 나타났다. 보다 더 정교한 온실가스 예측을 위해서는 기후특성, 토양특성, 작물경작특성 및 작물생육 특성을 고려하여 예측하는 것이 중요하며, DNDC 모형의 신뢰도를 높이려면 국내 농업생태계의 환경 및 생물인자를 모의할 수 있는 세부모형을 개발하는 것이 필요하다.