• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.320-322
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• 2013

무선센서네트워크에서 MAC 프로토콜은 듀티사이클을 이용하여 센서노드의 에너지 소비를 줄임으로써 배터리의 수명을 연장한다. 기존에 제안된 TA (Traffic-Adaptive)-MAC 프로토콜은 비동기 방식 기반으로 듀티사이클을 조절하여 센서노드의 에너지 소비를 줄인다. 본 기법은 네트워크의 트래픽 상태를 고려하여 동적으로 센서노드의 듀티사이클을 조정한다. 이러한 방법으로 센서노드의 대기시간을 줄이고 센서노드의 에너지를 효과적으로 사용한다. 하지만 이 기법은 네트워크의 트래픽 변화가 잦은 환경에서는 좋지 못한 효율을 보인다. 따라서 본 논문에서는 기존의 TA-MAC 기법에 가중이동평균 방법을 적용하여 합리적인 듀티사이클 선정을 위한 트래픽 계산 방법을 제안한다. 이는 최근 트래픽 값과 현재 감지한 트래픽의 평균을 계산하고 다음 트래픽을 예측하여 네트워크 트래픽이 급격히 변화하는 불안정한 환경에서 더 합리적인 듀티사이클 선정을 돕는다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.169-176
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• 2018

In this paper, we consider duty-cycled wireless sensor networks (WSNs) in which sensor nodes are periodically dormant in order to reduce energy consumption. In such networks, as the duty cycle interval increases, the energy consumption decreases. However, a higher duty cycle interval leads to the increase in the end-to-end (E2E) delay. Many applications of WSNs are delay-sensitive and require packets to be delivered from the sensr nodes to the sink with delay requirements. Most of existing studies focus on only reducing the E2E delay, rather than considering the delay bound requirement, which makes hard to achieve the balanced performance between E2E delay and energy consumption. A few study that considered delay bound requirement require time synchronization between neighboring nodes or a specific distribution of deployed nodes. In order to address limitations of existing works, we propose a duty-cycle scheduling algorithm that aims to achieve low energy consumption, while satisfying the delay requirements. To that end, we first estimate the probability distribution for the E2E delay. Then, by using the obtained distribution we determine the maximal duty cycle interval that still satisfies the delay constraint. Simulation results show that the proposed design can satisfy the given delay bound requirements while achieving low energy consumption.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.6
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• pp.91-97
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• 2022

There is hare and tortoise racing algorithm(HTA) for single-source(SS) singly linked list(SLL) with O(n) time complexity. But the fast method is unknown for general graph with multi-source, multi-destination, and multi-branch(MSMDMB). This paper suggests linear time cycle detection algorithm for given undirected and digraph with MSMDMB. The proposed method reduced the given graph G contained with unnecessary vertices(or nodes) to cycle into reduced graph G' with only necessary vertices(or nodes) to cycle based on the condition of cycle formation. For the reduced graph G', we can be find the cycle set C and cycle length λ using linear search within linear time. As a result of experiment data, the proposed algorithm can be obtained the cycle for whole data.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.2
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• pp.179-184
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• 2006

An intuitive understanding of the dynamic pattern generation in asymmetric networks may be considered an essential component in developing models for the dynamic information processing. It has been reported that the neural network with cyclic connections generates multiple limit cycles. The dynamics of discrete time network with cyclic connections has been investigated intensively. However, the dynamics of a cyclic connection neural network in continuous-time has not been well-known due to the considerable complexity involved in its calculation. In this paper, the dynamic behavior of a continuous-time cyclic connection neural network, in which each neuron is connected only to its nearest neurons with binary synaptic weights of ${\pm}1$, has been investigated. Furthermore, the dynamics and stability of the network have been analyzed using a piece-wise linear approximation.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.1
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• pp.13-19
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• 2013

The aim of this study was to investigate difference of the muscle activation patterns of the upper body during wheelchair cycle ramps ascent of different slopes for disabled with spinal cord injury. Three subjects who is disabled with spinal cord injury participated in this study. Surface electromyography (EMG) data (reaction time [RT], onset-offset time, and peak value of muscle activation) were collected biceps, triceps, upper trapezius, anterior deltoid, latissimus dorsi, and upper rectus abdominal muscles during wheelchair cycle ramps ascent ($0^{\circ}$, $3^{\circ}$, and $6^{\circ}$). For latissimus dorsi muscle, RT and peak value of muscle activation was were increased and offset time was delayed as the slope increased (p < 0.05). These results indicate that wheelchair cycle ramps ascent might cause excessive overuse of latissimus dorsi muscle.

• Journal of The Geomorphological Association of Korea
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• v.19 no.3
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• pp.109-121
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• 2012

Rock-surface temperatures were observed at a trachytic lava dome, called as Baeknokdam Northwest Face, in the summit area of Mt. Halla, Jeju Island, to examine the frequency and occurrence season of freeze-thaw cycles and the rate of temperature changes during a freezing period. Long-term measurements were recorded over 18 months from November 2006 to April 2008, at a 1-hour logging interval and rock depth of 1.5 cm. Both diurnal freeze-thaw cycles and effective freeze-thaw cycles appear in larger numbers on a south-facing rock face than a north-facing rock face. The diurnal cycles were dominantly observed on February and March for the south face and on November and April for the north face, respectively. The annual freeze-thaw cycles were confirmed in terms of the presence of seasonal freezing periods lasting from mid-November to mid-April for the south face and from early-November to late-April for the north face, respectively. The rate of decreasing temperatures during the seasonal freezing periods is larger on the north face than the south face. Notwithstanding the lower numbers of freeze-thaw events, the north face experiences a higher frost intensity since the number of hours below $-3^{\circ}C$ is larger on the north face than the south face. The number of freeze-thaw events and the duration of days with continuous sub-zero rock temperatures largely depend on the solar radiation controlled by the aspect of the monitored rock surfaces, and thus the high-frequency short-term frost cycle dominantly appears on the south face and the annual frost cycle on the north face, respectively.

• Journal of Welding and Joining
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• v.14 no.1
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• pp.38-46
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• 1996

High temperature low cycle fatigue crack growth behavior is investigated over a range of two temperatures and various frequencies in SUS 304 stainless steel. It is found that low frequency and temperature can enhance time-dependent crack growth. With high temperature, low frequency and long crack length, ${\Delta}J_c/{\Delta}J_ f$, the ratio of creep J integral range to fatigue J integral range is increased and time-dependent crack growth is accelerated. Interaction between ${\Delta}J_f$ and ${\Delta}J_c$ is occured at high frequency and low temparature and ${\Delta}J_c$, creep J integral range is fracture mechanical parameter on transition from cycle-dependent to time dependent crack growth in creep temperature region.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.4
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• pp.396-401
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• 2006

It is well-known that a neural network with cyclic connections generates plural limit cycles, thus, being used as a memory system for storing large number of dynamic information. In this paper, a continuous-time cyclic connection neural network was built so that each neuron is connected only to its nearest neurons with binary synaptic weights of ${\pm}1$. The type and the number of limit cycles generated by such network has also been demonstrated through simulation. In particular, the effect of chaos signal for transition between limit cycles has been tested. Furthermore, it is evaluated whether the chaotic noise is more effective than random noise in the process of the dynamical neural networks.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.137-153
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• 2019

Estimating tunnel construction time and costs are the most fundamental part of a tunnel project planning, which has been generally assessed on a deterministic basis until now. In this paper, excavation cycle time was investigated for two road tunnels and one subway tunnel, and the results were compared with the Standard of Construction Estimate (SE), which is made for the estimation of construction time and cost in a design stage. The results show that the difference in cycle time between SE and actual cycle time is 50%, 7% and 31% respectively for the three tunnels, which means that SE does not reflect practical operation time. The major reasons of the difference are skilled level of tunneling workers, the change of operation sequences for more effective operations, much more complicated working atmosphere in a tunnel than the assumption of SE etc. Finally, even though the results can not be generalized since investigated tunnels are only 3, but it is thought that SE needs to be upgraded into the model able to consider quite common situations through additional tunnel investigation and studies in the future.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.602-604
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• 2012

무선센서네트워크에서 센서노드가 에너지를 적게 사용하여 네트워크 시간을 연장하는 것은 중요한 이슈이다. 센서노드의 에너지 소비를 줄이기 위해 듀티사이클이 제안되었고 낮은 비동기식 듀티사이클에서 각 센서노드는 독립적으로 활성화되며 트래픽이 적은 경우에 에너지를 효율적으로 줄인다. 하지만 전송할 데이터가 증가하면 낮은 듀티사이클로 인해 송신노드는 수신노드의 활성화시간까지 많은 시간을 기다려야 한다. 이때 사용하는 에너지는 데이터 전송에 사용되는 에너지보다 크다는 문제점이 있다. 이를 해결하기 위해 전송노드는 자신보다 잔여 에너지가 큰 이웃노드에게 데이터를 전송하고 비활성상태로 전환되고 데이터를 모아 전송하는 OC-MAC 기법이 제안되었다. 하지만 OC-MAC 기법은 데이터를 위임할 이웃노드 선택시 자신보다 잔여 에너지가 큰 노드들 중 잔여 에너지가 제일 적은 노드를 선택한다. 이에 따라 센서노드들이 에너지를 균형있게 사용하지 못하는 문제점이 발생한다. 따라서 본 논문이 제안하는 기법은 이웃노드 중 잔여 에너지가 큰 이웃노드에게 데이터를 전송함으로 센서노드의 에너지를 균형 있게 사용하고 무센서네트워크 수명을 연장한다.