• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.3104-3110
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• 2011

This paper describes how to ensure safety of train by guaranteeing stable and continuous communication in RF-CBTC. CBTC System uses the wireless communication between onboard and wayside so that safety of wireless communication is the most important. Losing the position of train causes vital problem of train service. By losing the position of train, the other trains are blocked in the block and the train move by emergency mode so headway and safety cannot guaranteed. Therefore, safety is ensured by redundancy of wireless equipment. One of the ways to make redundancy is redundancy of equipment. However, the redundancy of equipment spends a lot of money to avoid interference in limited place like underground. Continuous communication is guaranteed by means of redundancy of wireless communication coverage to solve the problems even though one of the equipment is broken.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.605-610
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• 2002

Eigenvalues are taken as performance criteria for structural damping design using viscoelastic material. Given material properties, optimal distribution of damping material is sought based on eigenvalue sensitivity. For eigenanalysis of frequency dependent viscoelastic material treated structures, Golla-Mushes-McTavish (GHM) model is used and some dominant modes are chosen for consideration. To avoid the intensity of computation caused by increased problem size, an alternative approximate method is proposed which uses elastic modes and can be applied under small damping assumption. A cantilever beam treated with unconstrained viscoelastic layer is tested and optimal distribution of thickness of the layer is illustrated. Partial coverage configurations are compared with the one-sided full coverage case.

• 한국통신학회논문지
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• 제21권8호
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• pp.1948-1957
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• 1996

통신 프로토콜의 적합성 시험은 구현된 프로토콜이 표준규격과 동일하게 구현되었는지를 검사하는 과정을 말한다. 생성된 시험 항목이 어느 정도의 오류를 발견해 낼 수 있는지를 평가함으로써 적합성 시험의 효율성을 평가하는 하나의 기준으로 사용될 수 있다. 시험 항목의 오류 발견 능력의 평가 방법은 주로 수학적 평가 방법과 시뮬레이션을 이용한 연구가 이루어져 왔다. 본 논문에서는 기존 평가 방법의 문제점을 지적하고 오류 모델을 사용하여 생성된 시험항목에 대한 새로운 오류 발견 평가 모델을 제시하였다. 그리고 제안된 평가 모델을 기존의 방법과 비교, 분석하여 타당성을 입증하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권3호
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• pp.477-493
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• 2011

The IEEE 802.16 mobile multi-hop relay (MMR) task group 'j' (TGj) has introduced the multi-hop relaying concept in the IEEE 802.16 Wireless MAN, wherein a relay station (RS) is employed to improve network coverage and capacity. Several RSs can be deployed between a base station and mobile stations, and configured to form a tree-like multi-hop topology. In such architecture, we consider the problem of a path selection through which the mobile station in and outside the coverage can communicate with the base station. In this paper, we propose a new path selection algorithm that ensures more efficient distribution of resources such as bandwidth among the relaying nodes for improving the overall performance of the network. Performance of our proposed scheme is compared with the path selection algorithms based on loss rate and the shortest path algorithm. Based on the simulation results using ns-2, we show our proposal significantly improves the performance on throughput, latency and bandwidth consumption.

• 한국시뮬레이션학회논문지
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• 제13권2호
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• pp.23-34
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• 2004

Regenerative simulation (RS) is a method of stochastic steady-state simulation in which output data are collected and analysed within regenerative cycles (RCs). Since data collected during consecutive RCs are independent and identically distributed, there is no problem with the initial transient period in simulated processes, which is a perennial issue of concern in all other types of steady-state simulation. In this paper, we address the issue of experimental analysis of the quality of sequential regenerative simulation in the sense of the coverage of the final confidence intervals of mean values. The ultimate purpose of this study is to determine the best version of RS to be implemented in Akaroa2 [1], a fully automated controller of distributed stochastic simulation in LAN environments.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.267.1-267.1
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• 2013

In modern science and technology, the organization of building blocks, such as spherical particles and zeolite, is important to form a nanostructure. So, it is essential to develop methods for organizing them into large scale for many precise applications. Up to now, reflux and stirring is widely used method for organization of colloidal particles. However, because this method is hard to organize building block with high coverage and uniform orientation, it is necessary to research another method. In this work, we synthesized spherical silica particles using St$\"{o}$ber method and organized them on the glass which is coated with 3-chloropropyltrimethoxysilane (CP-TMS) and polyethyleneimine (PEI) using Sonication method. Although spherical silica particles are difficult to attach on the glass due to their small attachment site, we improved this problem by coating PEI. We introduced two mode of reaction promotion, sonication (SO) and sonication with stacking between the bare glass (SS), and investigated degree of coverage (DOC) and degree of close packing (DCP).

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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• pp.4177-4190
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• 2015

Current research on Internet of Things (IoT) has primarily addressed the means to enhancing smart resource allocation, automatic network operation, and secure service provisioning. In particular, providing satisfactory security service in IoT systems is indispensable to its mission critical applications. However, limited resources prevent full security coverage at all times. Therefore, these limited resources must be deployed intelligently by considering differences in priorities of targets that require security coverage. In this study, we have developed a new application of Cognitive Radio (CR) technology for IoT systems and provide an appropriate security solution that will enable IoT to be more affordable and applicable than it is currently. To resolve the security-related resource allocation problem, game theory is a suitable and effective tool. Based on the Blotto game model, we propose a new strategic power allocation scheme to ensure secure CR communications. A simulation shows that our proposed scheme can effectively respond to current system conditions and perform more effectively than other existing schemes in dynamically changeable IoT environments.

• 한국측량학회지
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• 제17권3호
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• pp.197-203
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• 1999

GPS의 이동측량 방법을 사용하여 위치정보와 속성정보를 취득하는 경우, 대상지의 지형학적 위치와 여러가지 오차요인에 의해 이상점이 발생하게 된다. 본 연구에서는 절사평균 방법과 1차 미분을 이용한 이상점 검출 알고리즘을 작성하고, 선형보간법과 다항식보간법을 사용하여 이상점 보간을 하였다. 또한 정확하게 보간된 데이터를 이용하여 국도 30 km구간에 대해 수치지도를 제작하였으며 수치지도를 제작하는 과정에서 발생될 수 있는 문제점들을 고찰하고 문제점들의 해결을 통해 정확한 GIS 커버리지 맵을 작성하였다.

• 로봇학회논문지
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• 제16권2호
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• pp.122-129
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• 2021

For the Simultaneous Localization and Mapping (SLAM) problem, a different path results in different SLAM results. Usually, SLAM follows a trail of input data. Active SLAM, which determines where to sense for the next step, can suggest a better path for a better SLAM result during the data acquisition step. In this paper, we will use reinforcement learning to find where to perceive. By assigning entire target area coverage to a goal and uncertainty as a negative reward, the reinforcement learning network finds an optimal path to minimize trajectory uncertainty and maximize map coverage. However, most active SLAM researches are performed in indoor or aerial environments where robots can move in every direction. In the urban environment, vehicles only can move following road structure and traffic rules. Graph structure can efficiently express road environment, considering crossroads and streets as nodes and edges, respectively. In this paper, we propose a novel method to find optimal SLAM path using graph structure and reinforcement learning technique.

• 반도체디스플레이기술학회지
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• 제22권1호
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• pp.49-53
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• 2023

In this paper, we propose an antirandom pattern-based test method considering power consumption to compensate for the problem that the fault coverage through random test decreases or the test time increases significantly when the DUT circuit structure is complex or large. In the proposed method, a group unit test pattern generation process and rearrangement process are added to improve the problems of long calculation time and high-power consumption, which are disadvantages of the previous antirandom test.