• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6B
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• pp.316-324
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• 2007

In this paper we proposed an energy consumption model for IR-UWB wireless sensor networks. The model takes the advantages of PHY-MAC cross layer design, and we used slotted and un-slotted sleeping protocols to compare the energy consumption. We addressed different system design issues that are responsible to energy consumption and proposed an optimum model for the system design. We expect the slotted sleeping will consume less energy for bursty load than that of the un-slotted one. But if we consider latency, the un-slotted sleeping model performs better than the slotted sleeping case.

• Journal of Information Processing Systems
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• v.2 no.1
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• pp.39-43
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• 2006

In this paper, we proposed TASL-MAC, a medium-access control (MAC) protocol for wireless sensor networks. In wireless sensor networks, sensor nodes are usually deployed in a special environment, are assigned with long-term work, and are supported by a limited battery. As such, reducing the energy consumption becomes the primary concern with regard to wireless sensor networks. At the same time, reducing the latency in multi-hop data transmission is also very important. In the existing research, sensor nodes are expected to be switched to the sleep mode in order to reduce energy consumption. However, the existing proposals tended to assign the sensors with a fixed Sleep/Listening schedule, which causes unnecessary idle listening problems and conspicuous transmission latency due to the diversity of the traffic-load in the network. TASL-MAC is designed to dynamically adjust the duty listening time based on traffic load. This protocol enables the node with a proper data transfer rate to satisfy the application's requirements. Meanwhile, it can lead to much greater power efficiency by prolonging the nodes' sleeping time when the traffic. We evaluate our implementation of TASL-MAC in NS-2. The evaluation result indicates that our proposal could explicitly reduce packet delivery latency, and that it could also significantly prolong the lifetime of the entire network when traffic is low.

• Journal of Communications and Networks
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• v.17 no.6
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• pp.602-608
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• 2015

In this paper, the limited error tracking problem is investigated for distributed leader-following wireless sensor networks (LFWSNs), where all sensors share data by the local communications, follower sensors are influenced by leader sensors directly or indirectly, but not vice versa, all sensor nodes track a reference state that is determined by the states of all leader sensors, and tracking errors are limited. In a LFWSN, the communicating graph is mainly expressed by some complete subgraphs; if we fix subgraphs that are composed of all leaders while all nodes in complete subgraphs of followers run on the sleeping-awaking method, then the fixed leaders and varying followers topology is obtained, and the switching topology is expressed by a Markov chain. It is supposed that the measurements of all sensors are corrupted by additive noises. Accordingly, the limited error tracking protocol is proposed. Based on the theory of asymptotic boundedness in mean square, it is shown that LFWSN keeps the limited error tracking under the designed protocol.

• Journal of Communications and Networks
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• v.16 no.4
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• pp.421-429
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• 2014

We consider the problem of scheduling communications in wireless sensor networks (WSNs) to ensure battery preservation through the use of the sleeping mode of sensors.We propose a communication protocol for 1-hop WSNs and extend it to multi-hop WSNs through the use of a 1-hop clustering algorithm.We propose to schedule communications in each cluster in a virtual communication ring so as to avoid collisions. Since clusters are cliques, only one sensor can speak or listen in a cluster at a time, and all sensors need to speak in each of their clusters at least once to realize the communication protocol. We model this situation as a mathematical program.

• The Korean Journal of Rehabilitation Nursing
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• v.13 no.2
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• pp.97-104
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• 2010

Purpose: This study was to investigate difficulties in daily activities and tingling from patients having treatment of FOLFOX chemotherapy after colon resection. Method: This study included 103 patients hospitalized for FOLFOX chemotherapy in one of the university affiliated hospital from August 1, 2008 through September 30, 2009. Data were collected using the questionnaire comprised general symptoms, tingling, difficulties in daily activities and coping behavior. Using the SPSS 14.0 program, data analytic methods include Chi-Square test, ANOVA, Scheffe's test. Results: The tingling sensation occurred in hands, feet, mouth, throat. Contacts with cold objects and the number of chemotherapy cycle worsen tingling sensation. Patients experienced difficulties in daily activities such as personal hygiene, kitchen work, eating cold food, sleeping cold, using fine motors like button up, writing, or using knife. The coping behavior included drinking warm water, sleeping warm, using gloves and socks, wearing comfortable shoes, massaging hands and getting help from supporters. Conclusion: An educational guideline for promoting coping behavior to relieve tingling sensation and difficulty in daily living in patients with FOLFOX chemotherapy is needed.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.1
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• pp.20-24
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• 2009

sensor node work limited energy. It is undesirable or impossible to replace the batteries that are depleted of energy because of characteristics of the sensor network. Due to the specific energy constrained environment, MAC design for sensor networks generally has to take energy consumption as one of its primary concerns. But in sensor networks, latency has been a key factor affecting the applicability of sensor networks to some delay-sensitive applications. Therefore, we propose MAC protocols based DSMAC in this paper. Which is able to dynamically change the sleeping and duty cycle of sensors is adjusted to adapt to packet amounts in buffer. Proposed MAC has energy efficiency and low latency, compared DSMAC.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.12
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• pp.1273-1277
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• 2011

This paper proposes a control-based approach for duty cycle adaptation in wireless sensor networks. The proposed method, QCon, controls duty cycle through queue management in order to achieve high performance under variable traffic rates. To minimize energy consumption while meeting delay requirement, we design a feedback controller, which adapts the sleeping time according to dynamically changing traffic by constraining the queue length at a predetermined value. Based on control theory, we analyze the adaptive behavior of QCon and derive conditions for system stability. Results from asymptotic analysis and simulations indicate that QCon outperforms existing scheduling protocol by achieving more energy savings while satisfying delay requirement.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.240-244
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• 2006

무선 센서 네트워크의 노드들은 소형으로써 배터리로 작동하고, 사용자로부터 원거리 또는 산악지대와 같이 배터리 교체가 쉽지 않은 곳에 배치되기 때문에 한정된 에너지를 효율적으로 사용하는 기술이 매우 중요하다. 이를 위해서 같은 지역에 대해 중첩되게 센싱하고 있는 노드들이 있다면 적정한 수의 노드만 활동하게 하고 나머지는 활동하지 않게 함으로써 노드들의 에너지 사용 효율을 높일 수 있다. 본 논문에서는 센서 노드가 유효센싱범위(ESA, Effective Sensing Area)를 계산하여 threshold초과 여부에 따라 working/sleeping하도록 함으로써 중첩되는 센싱범위를 최소화 하고 전체 센싱 커버리지를 유지시키면서 네트워크 수명을 증가시키는 스케줄링 프로토콜을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6A
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• pp.506-514
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• 2009

To minimize energy consumption, most of MAC Protocols in WSNs exploit low duty cycling. Among those, RMAC [4] allows a node to transmit a data packet for multiple hops in a single duty cycle, which is made possible by exploiting a control frame named Pioneer (PION) in setting up the path. In this paper, we present a MAC Protocol called Hop Extended MAC (HE-MAC) that transmits the data packet for more multiple hops in a single duty cycle. It employs an EXP (Explorer) frame to set up the multiple hop transmission, which contains the information of the maximum hop that a packet can be transmitted. With the use of the information in EXP and an internal state of Ready to Receive (RTR), HEMAC extends the relay of the packet beyond the termination of the data period by two more hops compared to RMAC. Along with our proposed adaptive sleeping method, it also reduces power consumption and handles heavy traffic efficiently without experiencing packet inversion observed in RMAC. We analytically obtain the packet delivery latency in HE-MAC and evaluate the performance through ns-2 simulations. Compared to RMAC, HE-MAC achieves 14% less power consumption and 20% less packet delay on average for a random topology of 300 nodes.

• The Journal of Korean Medicine
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• v.31 no.6
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• pp.40-46
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• 2010

Objective: This study investigated the therapeutic possibility of natural therapy in atopy-camp for children with atopic dermatitis. Methods: 30 children (19 boys and 11 girls, median age 11.5 years, ranging from 9 to 15) participated in natural environment-based activities in a camp-village located in Geumsan-gun for five days. Assessment of symptom change was conducted by self-reporting numeric scale (NRS) for pruritus and sleeping difficulty, investigator global assessment (IGA), eczema area and severity index (EASI score), serum histamine and IgE concentration before and after the camp period. Statistical significance was analyzed by paired t-test. Results: NRS for pruritus ($4.7{\pm}2.0$ into $4.3{\pm}2.1$), sleeping difficulty ($3.1{\pm}2.1$ into $2.9{\pm}2.0$), and serum histamine concentration ($4.27{\pm}7.39$ mol / L into $3.21{\pm}6.08$ mol / L) showed positive changes but didn't reach statistical significance (p > 0.05). IGA ($3.8{\pm}0.9$ into $4.13{\pm}1.0$), while EASI score ($10.8{\pm}9.7$ into $9.1{\pm}9.2$) and IgE ($408{\pm}320$ IU / mL into $385{\pm}3.8$ IU / mL) were significantly improved (p < 0.01). Conclusions: In spite of the limitation of the clinical trial protocol, this study may provide the possibility of natural environment-based therapy for children with atopic dermatitis.