• 한국지반신소재학회논문집
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• 제1권1호
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• pp.23-29
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• 2002

1980년대 이래 일본 및 미국등에서 연약지반상에 구축된 기존철도의 보수 및 보강시 지오셀 시스템을 이용하여 철도노반의 지지력을 높이는 보강기법들에 대한 연구가 활발히 진행되고 있다. 본 연구에서는 기존 철도의 보수 및 보강을 위해 지오셀 시스템으로 보강된 철도노반에 대해 국내외에서 이미 수행된 연구결과들을 분석하고 평가 하였다. 그리고 이들 결과를 토대로 지반의 변형계수 Ev를 시용하여 철도노반의 두께를 산정하는 다층이론에 근거를 둔 등가방법에 의한 설계방법을 개발하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.567-573
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• 2003

Korean High Speed Train (KHST) has been tested on high speed line in JungBu site since it was developed in 2002. The data acquisition system was developed to accomplish successfully this on-line test for proving the dynamic Performance of KHST. This system was consist of the personal computers based on National Instrument PXI modules and the test programs based on Labview 6i. This paper shows that this system is efficient to acquire the test data through the multi-channels connected the accelerometers which located in long distance places and flexible to change and add channels for data acquisition. The dynamic analysis of an on-line test is very complicate because the environmental conditions, as examples radius of curve, inclination of the track, tunnels, bridges, and so forth, and running conditions, as examples driving, braking, the number of working motors, and so forth, have an effect on the results. Therefor, the analysis method is important and this paper proposes the efficient procedure graphically, showing the proposed method simplify the accelerations of 5th bogie frame acquired during the on-line test for KHST.

• Structural Engineering and Mechanics
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• 제55권5호
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• pp.1015-1035
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• 2015

A three-dimensional (3D) numerical analysis for the train-bridge interaction (TBI) system is actively developed in this study in order to investigate the vibration characteristics of rigid-frame reinforced concrete (RC) viaducts in both vertical and lateral directions respectively induced by running high-speed trains. An analytical model of the TBI system is established, in which the high-speed train is described by multi-DOFs vibration system and the rigid-frame RC viaduct is modeled with 3D beam elements. The simulated track irregularities are taken as system excitations. The numerical analytical algorithm is established based on the coupled vibration equations of the TBI system and verified through the detailed comparative study between the computation and testing. The vibration responses of the viaducts such as accelerations, displacements, reaction forces of pier bottoms as well as their amplitudes with train speeds are calculated in detail for both vertical and lateral directions, respectively. The frequency characteristics are further clarified through Fourier spectral analysis and 1/3 octave band spectral analysis. This study is intended to provide not only a simulation approach and evaluation tool for the train-induced vibrations upon the rigid-frame RC viaducts, but also instructive information on the vibration mitigation of the high-speed railway.

• International Journal of Computer Science & Network Security
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• 제21권8호
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• pp.342-352
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• 2021

Multicast Routings is a big challenge due to limitations such as node power and bandwidth Mobile Ad-hoc Network (MANET). The path to be chosen from the source to the destination node requires protocols. Multicast protocols support group-oriented operations in a bandwidth-efficient way. While several protocols for multi-cast MANETs have been evolved, security remains a challenging problem. Consequently, MANET is required for high quality of service measures (QoS) such infrastructure and application to be identified. The goal of a MANETs QoS-aware protocol is to discover more optimal pathways between the network source/destination nodes and hence the QoS demands. It works by employing the optimization method to pick the route path with the emphasis on several QoS metrics. In this paper safe routing is guaranteed using the Secured Multicast Routing offered in MANET by utilizing the Ant Colony Optimization (ACO) technique to integrate the QOS-conscious route setup into the route selection. This implies that only the data transmission may select the way to meet the QoS limitations from source to destination. Furthermore, the track reliability is considered when selecting the best path between the source and destination nodes. For the optimization of the best path and its performance, the optimized algorithm called the micro artificial bee colony approach is chosen about the probabilistic ant routing technique.

• 무역학회지
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• 제44권4호
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• pp.205-220
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• 2019

This article recapitulates the recent changes in trade laws, which may be accentuated due to the intriguing emergence of fortified protectionism and Mega FTAs. It points out the need to formulate not only the corporate strategy for enhancing the product differentiation and architectural capabilities but also the public policy, which comprises the industrial adjustment policy to cope with possible negative impulses caused by the digital trade and foreign direct investment. It is imperative for Korea to facilitate the alignment between corporate strategy and industrial adjustment policy as an effective means of enhancing industrial structure by nurturing those linkage effects between relevant forward and backward industries. Given the drastically volatile trade norms of multi-track trade policies, it may be a pivotal momentum for Korea to pursue a paradigm shift of its trade policy with a prime objective of achieving such an alignment between corporate strategy and industrial adjustment policy, which affords increased value-added and the further development of product or generic technology instead of resorting to the misuses and abuses of economies of scale and production technology for the maximization of export amount.

• 한국인터넷방송통신학회논문지
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• 제22권5호
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• pp.123-128
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• 2022

정확한 모드전송선로 이론 (MTLT)을 적용하여 원추형 광 입사에서 공진 회절격자의 특성을 조사하였다. 원추형 구성에서 공진 회절과 관련된 모드 벡터가 전형적이 구조의 회절격자와 관련된 것보다 입사각에 따라 작게 변한다는 것을 보여주었다. 더욱이, 소멸하는 회절파가 공진 효과를 담당하는 누설 모드를 구동함에 따라, 원추형 장착은 기존 회절격자보다 더 큰 각도 허용 오차를 회절격자에 부여함을 보였다. 이에 기초하여, 수치 계산을 통하여 원추형 입사에서 발견된 스펙트럼을 사용하여, 원추형 및 클래식 구성에서 공진 회절격자의 각도-스펙트럼과 파장-스펙트럼 성능을 정량화하였다. 이러한 결과는 효율적이고 물리적으로 희소한 공진 회절격자를 요구하는 다양한 응용 분야에서 유용할 것이다.

• 대한의용생체공학회:의공학회지
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• 제42권5호
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• pp.232-240
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• 2021

Heterogeneity in cancer is the major obstacle for precision medicine and has become a critical issue in the field of a cancer diagnosis. Many attempts were made to disentangle the complexity by molecular classification. However, multi-dimensional information from dynamic responses of cancer poses fundamental limitations on biomolecular marker-based conventional approaches. Cell morphology, which reflects the physiological state of the cell, can be used to track the temporal behavior of cancer cells conveniently. Here, we first present a hybrid learning-based platform that extracts cell morphology in a time-dependent manner using a deep convolutional neural network to incorporate multivariate data. Feature selection from more than 200 morphological features is conducted, which filters out less significant variables to enhance interpretation. Our platform then performs unsupervised clustering to unveil dynamic behavior patterns hidden from a high-dimensional dataset. As a result, we visualize morphology state-space by two-dimensional embedding as well as representative morphology clusters and trajectories. This cell morphology profiling strategy by hybrid learning enables simplification of the heterogeneous population of cancer.

• Wind and Structures
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• 제32권5호
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• pp.487-499
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• 2021

The wind-blown sand effect on the high-speed train is investigated. Unsteady RANS equation and the SST k-ω turbulent model coupled with the discrete phase model (DPM) are utilized to simulate the two-phase of air-sand. Sand impact force is calculated based on the Hertzian impact theory. The different cases, including various wind velocity, train speed, sand particle diameter, were simulated. The train's flow field characteristics and the sand impact force were analyzed. The results show that the sand environment makes the pressure increase under different wind velocity and train speed situations. Sand impact force increases with the increasing train speed and sand particle diameter under the same particle mass flow rate. The train aerodynamic force connected with sand impact force when the train running in the wind-sand environment were compared with the aerodynamic force when the train running in the pure wind environment. The results show that the head car longitudinal force increase with wind speed increasing. When the crosswind speed is larger than 35m/s, the effect of the wind- sand environment on the train increases obviously. The longitudinal force of head car increases 23% and lateral force of tail increases 12% comparing to the pure wind environment. The sand concentration in air is the most important factor which influences the sand impact force on the train.

• Smart Structures and Systems
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• 제29권2호
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• pp.361-374
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• 2022

As civil infrastructure has continued to age worldwide, its structural integrity has been threatened owing to material deteriorations and continual loadings from the external environment. Structural Health Monitoring (SHM) has emerged as a cost-efficient method for ensuring structural safety and durability. As SHM research has gradually addressed an increasing number of structure-related problems, it has become difficult to understand the changing research topic trends. Although previous review papers have analyzed research trends on specific SHM topics, these studies have faced challenges in providing (1) consistent insights regarding macroscopic SHM research trends, (2) empirical evidence for research topic changes in overall SHM fields, and (3) methodological validations for the insights. To overcome these challenges, this study proposes a framework tailored to capturing the trends of research topics in SHM through a bibliometric and network analysis. The framework is applied to track SHM research topics over 15 years by identifying both quantitative and relational changes in the author keywords provided from representative SHM journals. The results of this study confirm that overall SHM research has become diversified and multi-disciplinary. Especially, the rapidly growing research topics are tightly related to applying machine learning and computer vision techniques to solve SHM-related issues. In addition, the research topic network indicates that damage detection and vibration control have been both steadily and actively studied in SHM research.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2022년도 추계학술대회
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• pp.236-239
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• 2022

증강현실로 날씨, 뉴스 요약 등이 제공되거나 AI 비서 기능을 제공하는 스마트 미러(smart mirror)가 개발되고 있다. 본 작품에서는 IoT 통합제어, 뉴스 요약 및 날씨 정보 제공 등의 서비스를 하나의 웹 플랫폼으로 구축하고 이를 손가락 제스쳐 및 음성 명령으로 제어하는 것을 제안하고 구현하였다. 본 작품에서는 음성 인식을 통해 IoT 서비스를 직관적으로 이용할 수 있게끔 설계하여 사용자의 편의성을 높였으며, 디바이스를 직접 터치하는 방식이 아닌 finger gesture로 제어하는 방식을 채택해, 디바이스 유지 보수 및 위생 문제를 해결하였다. 단순 IoT 통합 제어 기능뿐만 아니라 다양한 컨텐츠 및 기능을 제공함으로써 통합 플랫폼의 기능을 수행할 수 있도록 하였다. 뉴스 홈페이지에서 Crawling한 뉴스를 text rank 알고리즘을 이용. 자동으로 요약하는 기능과, 사용자의 IP를 기반으로 위도와 경도를 추론, 해당 지역의 일기 예보 정보를 표현해 주는 등 단순 IoT 제어 플랫폼이 아닌, 통합 플랫폼의 기능을 다하도록 설계하였다. 이처럼 다양한 정보를 압축해서 사용자가 편하게 볼 수 있도록 제공하며, 직관적인 two track 제어 방식을 채택. 사용 대상의 편의성을 증대시켜 본 프로젝트는 기존 프로젝트보다 사용자에게 더 나은 사용 경험을 제공할 것이다.