• Journal of Communications and Networks
• /
• 제11권4호
• /
• pp.337-349
• /
• 2009

In this paper, we introduce a novel mobility model for mobile sinks in which the sinks move towards randomly distributed destinations, where each destination is associated with a mission. The novel mobility model is termed the random mobility with destinations. There have been many studies on mobile sinks; however, they merely support two extreme cases of sink mobility. The first case features the most common and general mobility, with the sinks moving randomly, unpredictably, and inartificially. The other case takes into account mobility only along predefined or determined paths such that the sinks can gather data from sensor nodes with minimum overhead. Unfortunately, these studies for the common mobility and predefined path mobility might not suit for supporting the random mobility with destinations. In order to support random mobility with destination, we propose a new protocol, in which the source nodes send their data to the next movement path of a mobile sink. To implement the proposed protocol, we first present a mechanism for predicting the next movement path of a mobile sink based on its previous movement path. With the information about predicted movement path included in a query packet, we further present a mechanism that source nodes send energy-efficiently their data along the next movement path before arriving of the mobile sink. Last, we present mechanisms for compensating the difference between the predicted movement path and the real movement path and for relaying the delayed data after arriving of the mobile sink on the next movement path, respectively. Simulation results show that the proposed protocol achieves better performance than the existing protocols.

• International Journal of Internet, Broadcasting and Communication
• /
• 제12권4호
• /
• pp.93-101
• /
• 2020

Shipyards are potential environments for using IoT services, sensor networks, and delay tolerant networks. Simulations of those services and networks strongly rely on human mobility models. Results obtained with an unrealistic model may not reflect the true performance of applications, protocols, and algorithms in a shipyard. A lot of synthetic models for human movements have been studied but most of them are generic and focus on the daily movements of humans on city scales. Nevertheless, workers in shipyards have unique movement characteristics such as movement speed, pause time, and attractions places. For instance, workers usually move to some places, where they work, and rarely move to other places in the factory. Movement characteristics of workers not only depend on workers but also on tasks, which they do. For instance, workers, who paint ships, have similar movement speed and pause time. Hence, in this paper, human movements in shipyards are studied. We propose a new human mobility model called the human mobility mode in shipyards (MIS). In MIS, workers are classified into multiple types. Movement characteristics of a worker are similar to other workers in the same type. Based on the visiting probability, workers have some places, where they frequently visits, and some places, where they rarely visit. We analyze real mobility traces and studie to achieve human movement characteristics from real traces. The results show that MIS provides a well-match to the movement characteristic from real traces.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권6호
• /
• pp.2180-2200
• /
• 2015

This paper considers mobility control to improve packet delivery in delay-tolerant networks (DTNs) under group mobility. Based on the group structure in group mobility, we propose two mobility control techniques; group formation enforcement and group purposeful movement. Both techniques can be used to increase the contact opportunities between groups by extending the group's reachability. In addition, they can be easily integrated into some existing DTN routing schemes under group mobility to effectively expedite the packet delivery. This paper is divided into 2 parts. First, we study how our proposed mobility control schemes reduce the packet delivery delay in DTNs by integrating them into one simple routing scheme called group-epidemic routing (G-ER). For each scheme, we analytically derive the cumulative density function of the packet delivery delay to show how it can effectively reduce the packet delivery delay. Then, based on our second proposed technique, the group purposeful movement, we design a new DTN routing scheme, called purposeful movement assisted routing (PMAR), to further reduce the packet delay. Extensive simulations in NS2 have been conducted to show the significant improvement of PMAR over G-ER under different practical network conditions.

• 대한물리치료과학회지
• /
• 제24권1호
• /
• pp.49-58
• /
• 2017

Purpose: To determine the effect of Functional movement screen(FMS) of Healthy subjects. Method: 18 subjects were randomly assigned toFunctional movement screen test. To measure functional movement screen(deep squat, hurdle step, in line lunge, shoulder mobility reaching, active straight leg raise, trunk stability push up, rotary stability). Result: FMS scores were deep squat 2.61score, right hurdle step 2.67 score, lift hurdle step 2.83 score, in line lunge 2.83 score, right shoulder mobility 2.67 score, left shoulder mobility 2.61 score, right active straight-leg raise 3.00 score, left active straight-leg raise 3.00 score, trunk stability push up 2.33 score, rotary stability 1.94 score. Conclusion: FMS can improve functional movement in healthy adults.

• Journal of Communications and Networks
• /
• 제17권6호
• /
• pp.568-581
• /
• 2015

Predicting locations of users with portable devices such as IP phones, smart-phones, iPads and iPods in public wireless local area networks (WLANs) plays a crucial role in location management and network resource allocation. Many techniques in machine learning and data mining, such as sequential pattern mining and clustering, have been widely used. However, these approaches have two deficiencies. First, because they are based on profiles of individual mobility behaviors, a sequential pattern technique may fail to predict new users or users with movement on novel paths. Second, using similar mobility behaviors in a cluster for predicting the movement of users may cause significant degradation in accuracy owing to indistinguishable regular movement and random movement. In this paper, we propose a novel fusion technique that utilizes mobility rules discovered from multiple similar users by combining clustering and sequential pattern mining. The proposed technique with two algorithms, named the clustering-based-sequential-pattern-mining (CSPM) and sequential-pattern-mining-based-clustering (SPMC), can deal with the lack of information in a personal profile and avoid some noise due to random movements by users. Experimental results show that our approach outperforms existing approaches in terms of efficiency and prediction accuracy.

• 한국경제지리학회지
• /
• 제10권2호
• /
• pp.182-196
• /
• 2007

EU는 노동이동 자유화를 통해 일자리 창출과 성장을 추구해 왔다. 노동의 자유로운 이동은 노동자에게 새로운 고용기회의 창출과 기술습득의 기회를 제공하여 지속적인 성장을 이끈다. 그러나 경제요소가 불균등하게 분포되어 있는 지리적 공간에서 자유로운 노동이동은 지역간 노동이동의 차별성을 가져오며, 지역적 확대는 새로운 노동이동의 기회를 제공하여 노동이동의 지역적 재분배를 가져온다. EU의 노동이동은 남유럽 국가의 경제성장과 북유럽 국가의 서비스 및 첨단산업화로 남유럽 국가에서 북유럽 국가로의 이동에서 북유럽 국가에서 북유럽 국가로의 이동으로 변화되고 있다. 또한 미숙련 노동자의 이동성은 감소하고 고학력의 전문직 노동자의 이동성은 증가하고 있으며, 이들 고학력 이주자는 북유럽 국가에서 북유럽 국가로 이동하는 경향을 보인다. 반면에 일반 노동자는 남유럽 국가에서 북유럽 국가로, 북부 아프리카에서 남유럽 국가로 이동하는 계층구조를 형성하고 있다.

• 한국의류학회지
• /
• 제32권4호
• /
• pp.553-561
• /
• 2008

The purpose of this research was to analyze the relationship between the ease of crotch depth and the mobility of leg movement. Ten Korean men were participated as subjects and 0. 3, 6cm of crotch ease were inserted for test clothes. To analyze objectively, range-of-motion of four selected movements was measured by Leighton flexometer and goniometer. Also. wearer acceptability rating was measured for subjectively investigation. Anova and Duncan's range tests were used for statistical analysis. According to the results, 3cm of crotch ease was most comfortable. The mobility of test clothes with 3cm crotch ease was improved largely in every test movement(16.2% and 16.6% in segittal plane, and 6.1% and 6.2% in frontal motion).

• Journal of Communications and Networks
• /
• 제16권6호
• /
• pp.645-655
• /
• 2014

Latency, an identified element of Internet protocol (IP) mobility protocol execution, can reduce handover performance in mobile networks. Although the performance can be improved by applying an effective network-based IP mobility scheme in place of the traditional host-based alternatives, the existing inter-domain extensions of network-based IP mobility continue to suffer from an extended handover latency. This paper proposes a new inter-domain network-based IP mobility scheme based on node movement prediction. The proposed scheme accelerates the handover by preparing the future domain of the mobile node in a proactive manner. Analytical and simulation-based evaluations confirm improved performance of the proposed scheme in terms of handover latency and packet loss compared with existing schemes.

• 한국컴퓨터정보학회논문지
• /
• 제10권2호
• /
• pp.133-141
• /
• 2005

무선 이동 통신망에서 위치관리에 대한 성능분석을 위해서 사용자의 이동 패턴의 모의실험 방안에 대한 연구가 요구되고 있다. 이러한 목적에 따라 본 논문은 무선 이동 망에서의 이동패턴을 갖는 사용자의 이동성 모델을 제안한다. 이동 사용자들은 임의적으로 움직이기도 하지만 특정 시간대에 규칙적인 이동을 반복하는 특성도 함께 가지고 있다. 따라서 제안된 모델은 사용자의 시간에 연관된 이동을 묘사하도록 구성하였다. 이 모델은 지점 이동, 타임 슬롯에 대한 이동확률, 이동에 대한 지형적 경로 등으로 구성된다. 또한 임의적인 이동과 규칙적인 이동 특성이 혼합된 경우에 대한 모의실험 방안도 함께 제안된다. 모의실험 결과는 의도했던 이동패턴을 갖는 이동 시나리오를 생성할 수 있음을 보여준다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권3호
• /
• pp.1034-1051
• /
• 2016

Mobility models are invaluable for determining the performance of routing protocols in opportunistic networks. The movement of nodes has a significant influence on the topological structure and data transmission in networks. In this paper, we propose a new mobility model called the campus-based community mobility model (CBCNM) that closely reflects the daily life pattern of students on a real campus. Consequent on a discovery that the pause time of nodes in their community follows a power law distribution, instead of a classical exponential distribution, we abstract the semi-Markov model from the movement of the campus nodes and analyze its rationality. Then, using the semi-Markov algorithm to switch the movement of the nodes between communities, we infer the steady-state probability of node distribution at random time points. We verified the proposed CBCNM via numerical simulations and compared all the parameters with real data in several aspects, including the nodes' contact and inter-contact times. The results obtained indicate that the CBCNM is highly adaptive to an actual campus scenario. Further, the model is shown to have better data transmission network performance than conventional models under various routing strategies.