• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.9
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• pp.4301-4319
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• 2017

Adopting mobile chargers (MC) in rechargeable wireless sensors network (R-WSN) to recharge sensors can increase network efficiency (e.g., reduce MC travel distance per tour, reduce MC effort, and prolong WSN lifetime). In this study, we propose a mechanism to split the sensing field into partitions that may be equally spaced but differ in distance to the base station. Moreover, we focus on minimizing the MC effort by providing a new charging mechanism called the sector-based charging schedule (SBCS), which works to dispatch the MC in charging trips to the sector that sends many charging requests and suggesting an efficient sensor-charging algorithm. Specifically, we first utilize the high ability of the BS to divide the R-WSN field into sectors then it select the cluster head for each sector to reduce the intra-node communication. Second, we formulate the charging productivity as NP-hard problem and then conduct experimental simulations to evaluate the performance of the proposed mechanism. An extensive comparison is performed with other mechanisms. Experimental results demonstrate that the SBCS mechanism can prolong the lifetime of R-WSNs by increasing the charging productivity about 20% and reducing the MC effort by about 30%.

• Smart Media Journal
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• v.4 no.1
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• pp.25-32
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• 2015

Powering wireless sensors with energy harvested from the environment is coming of age due to the increasing power densities of both storage and harvesting devices and the electronics performing energy efficient energy conversion. In order to maximize the functionality of the wireless sensor network, minimize missing packets, minimize latency and prevent the waste of energy, problems like congestion and inefficient energy usage must be addressed. Many sleep-awake protocols and efficient message priority techniques have been developed to properly manage the energy of the nodes and to minimize congestion. For a WSN that is operating in a strictly energy constrained environment, an energy-efficient transmission strategy is necessary. In this paper, we present a novel transmission priority decision scheme for a heterogeneous body sensor network composed of normal nodes and an energy harvesting node that acts as a cluster head. The energy harvesting node's decision whether or not to clear a normal node for sending is based on a set of metrics which includes the energy harvesting node's remaining energy, the total harvested energy, the type of message in a normal node's queue and finally, the implementation context of the wireless sensor network.

• Journal of the Korean Society of Clothing and Textiles
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• v.43 no.6
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• pp.930-940
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• 2019

This study analyzes the facial data required for sheet design in order to pursue the facial compatibility of disposable sheets used in facial mask products that are increasing in popularity as self-care methods. The subjects of the study were 23 facial measurements of 1,001 women in their 20s to 60s from Size Korea's 6th 3D data. Through factor analysis, sheet-related facial measurements were collected into six factors included in the vertical length of each part of the face: length of face surface from the ear to each part of the face, width of eyes, nose, lips, length of nose, vertical length of lower face, width of the head and width of chin. Three sheet face types were classified using six factor scores as variables, and the characteristics of each type differed according to age group. As a result of the discriminant analysis to identify the dimension items that classify the three cluster types, 12 contributing items were extracted out of 23 items. This study provides useful information and data for further studies of products requiring facial fitness.

• The Korean Journal of Pain
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• v.8 no.2
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• pp.272-278
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• 1995

Headache is a common disease of the general population. But the main problem in any study of headache has been that of defining the disease entities. In 1988, the Headache Classification committee of the International Headache Society introduced operational diagnostic criteria for all headache disorders into 13 major group; migraine, tension-type headache, cluster headache and chronic paroxysmal hemicrania etc. Sjaastad was the first to describe "cervicogenic headache", one of various head pain syndromes that probably originate in the cervical spine. Between March 1995 and June 1995, we studied 78 out-patients of the Department of Neuro pain clinic, Sanggye Paik Hospital, Inje university. We divided the patients into three study group: Fifty-three patients with tension-type headache, 13 with cervicogenic headache, and 12 with migraine headache. The reponse of trigger point injection and $C_2$-ganglion block in patients was investigated. We paid particular attention to the response of trigger point injection in patients of the three group. The effect of trigger point injection was more marked in tension-type headache group than in the other categories. The pain reduction after $C_2$-ganglion block was more marked in cervicogenic headache group than in the others.

• Fashion & Textile Research Journal
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• v.1 no.2
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• pp.127-136
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• 1999

The purpose of this research was to investigate the difference between perceptions of the nude body and of the clothed body as measured by body cathexis scale. Subjects were 274 college male and female between 20~30 yrs. Data were analyzed by using frequency, T test, cluster analysis, Duncan test by using Spss for window 8.0 PC program. Significant difference were found between mean scores of male and female on the nude body cathexis (NBC) and clothed body cathexis (CBC) Scales for hair texture, hair color, face, face color, shape of head, eye, lips, forehead, back, trunk, waist, bust, leg of shape, chest, hip. On the difference between male and female, significant differences were found between NBC and CBC scales for all body parts except hair texture, face color, ears, eyes, teech. Male had higher satisfaction than female in both body cathexis. The taller men, the higher body satisfaction with face shape, body shape, height in both body cathexis. Before appearence management, the bigger men, the higher body satisfaction with musle, waist, height, chest, body shape in both body cathexis. Male had higher satisfaction than female in both body cathexis. The taller women, the higher body satisfaction with neck, body shape, height in before appearence management. The bigger women, the higher body satisfaction with heights, weight distributions, waist, height in both.

• ETRI Journal
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• v.33 no.6
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• pp.857-863
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• 2011

Due to uncertainties in target motion and randomness of deployed sensor nodes, the problem of imbalance of energy consumption arises from sensor scheduling. This paper presents an energy-efficient adaptive sensor scheduling for a target monitoring algorithm in a local monitoring region of wireless sensor networks. Owing to excessive scheduling of an individual node, one node with a high value generated by a decision function is preferentially selected as a tasking node to balance the local energy consumption of a dynamic clustering, and the node with the highest value is chosen as the cluster head. Others with lower ones are in reserve. In addition, an optimization problem is derived to satisfy the problem of sensor scheduling subject to the joint detection probability for tasking sensors. Particles of the target in particle filter algorithm are resampled for a higher tracking accuracy. Simulation results show this algorithm can improve the required tracking accuracy, and nodes are efficiently scheduled. Hence, there is a 41.67% savings in energy consumption.

• Journal of Communications and Networks
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• v.15 no.2
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• pp.164-172
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• 2013

We consider the problem of secure and robust clustering for quantized target tracking in wireless sensor networks (WSN) where the observed system is assumed to evolve according to a probabilistic state space model. We propose a new method for jointly activating the best group of candidate sensors that participate in data aggregation, detecting the malicious sensors and estimating the target position. Firstly, we select the appropriate group in order to balance the energy dissipation and to provide the required data of the target in the WSN. This selection is also based on the transmission power between a sensor node and a cluster head. Secondly, we detect the malicious sensor nodes based on the information relevance of their measurements. Then, we estimate the target position using quantized variational filtering (QVF) algorithm. The selection of the candidate sensors group is based on multi-criteria function, which is computed by using the predicted target position provided by the QVF algorithm, while the malicious sensor nodes detection is based on Kullback-Leibler distance between the current target position distribution and the predicted sensor observation. The performance of the proposed method is validated by simulation results in target tracking for WSN.

• Journal of Information Processing Systems
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• v.6 no.1
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• pp.53-66
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• 2010

The energy efficiency is a key design issue to improve the lifetime of the underwater sensor networks (UWSN) consisting of sensor nodes equipped with a small battery of limited energy resource. In this paper, we apply a hexagon tessellation with an ideal cell size to deploy the underwater sensor nodes for two-dimensional UWSN. Upon this setting, we propose an enhanced hybrid transmission method that forwards data packets in a mixed transmission way based on location dependent direct transmitting or uniform multi-hop forwarding. In order to select direct transmitting or uniform multi-hop forwarding, the proposed method applies the threshold annulus that is defined as the distance between the cluster head node and the base station (BS). Our simulation results show that the proposed method enhances the energy efficiency compared with the existing multi-hop forwarding methods and hybrid transmission methods

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.7
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• pp.3690-3713
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• 2019

According to the main group key management schemes logical key hierarchy (LKH), exclusion basis systems (EBS) and other group key schemes are limited in network structure, collusion attack, high energy consumption, and the single point of failure, this paper presents a group key management scheme for wireless sensor networks based on Lagrange interpolation polynomial characteristic (AGKMS). That Chinese remainder theorem is turned into a Lagrange interpolation polynomial based on the function property of Chinese remainder theorem firstly. And then the base station (BS) generates a Lagrange interpolation polynomial function f(x) and turns it to be a mix-function f(x)' based on the key information m(i) of node i. In the end, node i can obtain the group key K by receiving the message f(m(i))' from the cluster head node j. The analysis results of safety performance show that AGKMS has good network security, key independence, anti-capture, low storage cost, low computation cost, and good scalability.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.01a
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• pp.103-104
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• 2019

본 논문에서는 무선 센서 네트워크(Wireless Sensor Network, WSN) 환경에 배치되어 있는 각 센서들의 데이터 수집을 위한 싱크(Sink)가 일정 주기로 재배치되는 싱크 마이그레이션(Migration) 과정에서 센서 데이터를 종합하여 싱크로 전송하는 클러스터 헤드(Cluster Head, CH)의 자원 효율성 증대를 위해 중간 경로를 활용한 센서 할당 기법을 제안한다. 본 논문에서는 WSN 환경을 바탕으로 해당 기법을 적용하여 싱크 재배치 과정을 시뮬레이션 하였으며, 해당 실험의 결과에 따르면 클러스터 헤드의 자원 효율성 및 전체 센서 데이터의 수집률이 향상되었다.