• Korean Journal of Remote Sensing
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• v.31 no.4
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• pp.321-330
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• 2015

Atmospheric correction is an essential part in time-series analysis on biophysical parameters of surface features. In this study, we tried to examine possible problems in atmospheric correction of multitemporal High Spatial Resolution (HSR) images obtained from two different sensor systems. Three KOMPSAT-2 and two IKONOS-2 multispectral images were used. Three atmospheric correction methods were applied to derive surface reflectance: (1) Radiative Transfer (RT) - based absolute atmospheric correction method, (2) the Dark Object Subtraction (DOS) method, and (3) the Cosine Of the Uun zeniTh angle (COST) method. Atmospheric correction results were evaluated by comparing spectral reflectance values extracted from invariant targets and vegetation cover types. In overall, multi-temporal reflectance from five images obtained from January to December did not show consistent pattern in invariant targets and did not follow a typical profile of vegetation growth in forests and rice field. The multi-temporal reflectance values were different by sensor type and atmospheric correction methods. The inconsistent atmospheric correction results from these multi-temporal HSR images may be explained by several factors including unstable radiometric calibration coefficients for each sensor and wide range of sun and sensor geometry with the off-nadir viewing HSR images.

• Proceedings of the KOR-KST Conference
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• 2003.02a
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• pp.127-150
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• 2003

This research presents a novel application of static traffic assignment methods, but with a variable time value, for estimating the market share of a high-speed rail (HSR) in the NW-SE corridor of Korea which is currently served by the airline (AR), conventional rail (CR), and highway (HWY) modes. The proposed model employs the time-space network structure to capture the interrelations among all competing transportation modes, and to reflect their supply- and demand-sides constraints as well as interactions through properly formulated link-node structures. The embedded cost function for each network link offers the flexibility for incorporating all associated factors, such as travel time and fare, in the model computation, and enables the use of a distribution rather than a constant to represent the time-value variation among all transportation mode users. To realistically capture the tripmakers' value-of-time (VOT) along the target area, a novel method for VOT calibration has been developed with aggregate demand information and key system performance data from the target area. Under the assumption that intercity tripmakers often have nearly "perfect" travel information, one can solve the market share of each mode after operations of HSR for each O-D pair under the time-dependent demand with state-of-the-art traffic assignment. Aside from estimating new market share, this paper also investigated the impacts of HSR on other existing transportation modes.

• The Korean Journal of Health Service Management
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• v.12 no.2
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• pp.149-162
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• 2018

Objectives : This study aimed to develop tools to measure the social responsibility activities of hospitals using ISO 26000 and to verify the validity and reliability of the developed tools. We verified the content and structural validity, as well as the internal consistency of the proposed measurement tool for hospitals' social responsibility. Methods : We conducted an online survey on hospitals/employees from Feb 26 to Mar 12, 2018, and analyzed selected 197 respondents from the survey by removing incomplete responses. Results : The developed hospitals' CSR (HSR) measurement tool consists of 36 items with 5 factors: "consumer issues", "labor practices", "community involvement & development", "fair operating practice", and "environment". Analysis revealed high reliability with Cronbach' alpha of 0.981. Conclusions : It was verified that the developed HSR tool fully reflected hospital characteristics. This tool can be used to diagnose hospitals' social responsibility and to support strategic decision on social responsibility.

• Smart Structures and Systems
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• v.31 no.5
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• pp.501-516
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• 2023

Dynamic irregularity and acceleration of bridges subjected to high-speed trains provide crucial information for comprehensive evaluation of the health state of under-track structures. This paper proposes a novel approach for real-time estimation of vertical track dynamic irregularity and bridge acceleration using deep generative adversarial network (GAN) and vibration data from in-service train. The vehicle-body and bogie acceleration responses are correlated with the two target variables by modeling train-bridge interaction (TBI) through least squares generative adversarial network (LSGAN). To realize supervised learning required in the present task, the conventional LSGAN is modified by implementing new loss function and linear activation function. The proposed approach can offer pointwise and accurate estimates of track dynamic irregularity and bridge acceleration, allowing frequent inspection of high-speed railway (HSR) bridges in an economical way. Thanks to its applicability in scenarios of high noise level and critical resonance condition, the proposed approach has a promising prospect in engineering applications.

• Steel and Composite Structures
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• v.44 no.4
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• pp.473-488
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• 2022

A high-speed railway (HSR) bridge may undergo long-term deformation due to the degradation of material stiffness, or foundation settlement during its service cycle. In this study, an analytical model is set up to evaluate the influence of this long-term vertical bridge deformation on the track geometry. By analyzing the structural characteristics of the HSR track-bridge system, the energy variational principle is applied to build the energy functionals for major components of the track-bridge system. By further taking into account the interlayer's force balancing requirements, the mapping relationship between the deformation of the track and the one of the bridge is established. In order to consider the different behaviors of the interlayers in compression and tension, an iterative method is introduced to update the mapping relationship. As for the validation of the proposed mapping model, a finite element model is created to compare the numerical results with the analytical results, which show a good agreement. Thereafter, the effects of the interlayer's different properties of tension and compression on the mapping deformations are further evaluated and discussed.

• Journal of the Korean Society of Systems Engineering
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• v.4 no.2
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• pp.15-26
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• 2008

The Korean High-speed train was developed during 1996 to 2007. This development project consists of many sub-projects and the train-system includes a lot of sub-systems. In order to promote the project on planned cost and time effectively, we tried to apply systems engineering process during the whole life-cycle. The purpose of this paper is to introduce the systems engineering process applied to this project. Activities carried out in each phase such as pre-design, detailed-design, integration & verification are described.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.832-835
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• 2011

최근까지 용접구조물의 피로설계는 용접품질 수준에 따라 공칭응력 또는 핫스팟 응력에 의한 S-N선 도로부터 수행하였다. 본 연구에서는 유한요소망의 크기에 덜 민감하면서 기존의 하중모드형식, 두께 효과 및 용접결합형식에 상관없는 등가구조응력(E2S2) 접근법을 이용한 Master S-N선도로부터 철도차량 대차프레임의 피로수명을 평가하고자 한다. 또한 합리적인 철도차량 용접대차프레임의 피로해석 연구일환으로서, 다축피로조건인 EN규격의 피로시험조건하에 이의 피로수명을 평가하고자 한다.

• Journal of the Korean Society for Railway
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• v.10 no.2 s.39
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• pp.153-160
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• 2007

To start or stop the train safely within the limited traveling distance, it is necessary to guarantee the proper traction or braking force. Presently, most trains are run by the electrical power and have adopted a combined electrical and mechanical(friction) braking system. In order to design a good traction or a brake system, it is essential for designers to predict the traction or brake performance. In this paper, the traction/coasting/braking performances analysis program has been developed and verified by comparing the simulation results with on-line test results of the Korean high speed train(HSR-350); Both results match very well. Consequently, the designers can predict the traction/coasting/braking performances of trains by using the proposed program under various operating conditions.

• Journal of the Korean Society for Railway
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• v.9 no.6 s.37
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• pp.682-688
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• 2006

In this paper, a method which can deduce the traction farce or the braking force from the acceleration or the deceleration of the train, has been suggested. In the case of Korean high speed train (HSR-350x), the traction force and the braking forces have been obtained by using this method. It is proven that the proposed method is a very good tool in estimating the traction force or the braking force when the train starts or stops. Also, these forces on be used to calculate friction coefficients of mechanical brakes and the transmission efficiency of the traction system.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.85-90
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• 2007

Aerodynamically generated noise is significant when the train speed exceeds 250km/h. Experiments were performed in order to investigate the characteristics of aerodynamic noise sources generated from exterior of the HSR-350x, especially from the inter-coach spacing. Measurements of both the inside and outside of the cabin are carried out to investigate the characteristics of the noise. Effect of the size of the gap has been investigated through an wind tunnel test and it has been found that the low frequency noise is strongly dependent on the size of gap. Also performed is an array measurement to locate different noise sources from the high-speed train. Spectral characteristics of exterior noise sources have been examined through these experiments.