• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.1155-1158
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• 1999

In this paper, we consider the optimal control of detection threshold to minimize the conditional mean-square state estimation error for the probabilistic data association (PDA) filter. Earlier works on this problem involved the cumbersome graphical optimization algorithm or time-consuming numerical optimization algorithm. Using the numerical approximation of information reduction factor, we obtained the closed-form optimal detection threshold. This results are very useful for real-time implemenation.

• The Journal of Korean Academy of Prosthodontics
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• v.8 no.1
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• pp.77-79
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• 1968

The swallowing threshold tests were conducted on the 8 subjects over one month of full denture wearing experience of Korean. The results were follows. 1) The swallowing threshold of the full denture wearer was higher than that of the normal control group. 2) The swallowing threshold of the full denture wearer was different according to the quality and quantity of the test food. 3) The swallowing threshold of full denture wearer seemed to be no correlation between short and long duration of wearing experience.

• Journal of Satellite, Information and Communications
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• v.8 no.1
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• pp.61-65
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• 2013

In this paper, we propose system model to solve conventional threshold problem of using fixed false alarm for energy spectrum sensing. Spectrum sensing reliability is ensured when Secondary user have high SNR. Thus, it is not reasonable using fixed optional false alarm without considering CR user's SNR. So, we propose adaptive threshold method. adaptive threshold is decided by controling FA according to CR user's SNR.

• Korean Journal of Psychosomatic Medicine
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• v.7 no.1
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• pp.51-60
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• 1999

This study was designed to evaluate anxiety & depression symptoms and pressure pain threshold in patients with posttraumatic stress disorder(n=23) and to find out the relationship between the affective symptoms and the pressure pain threshold scores. And this was compared with healthy control subjects(n=18). The scores of pressure pain threshold were checked with algometer. The results were as follows : PTSD patients showed higher scores of anxiety & depression symptoms than that of the control group. In contrast with our hypothesis, pressure pain threshold in PTSD patients presented statistically significant higher scores than that of the control group. These results may be derived from following factors. First, chronic depression has influenced the pain perception of patients with PTSD rather than anxiety symptoms, second, abnormal state of the opiate system in PTSD patients, third, the sick role of the PTSD patients, fourth, the socio-environmental factor of the PTSD patients. In conclusion, affective symptoms, especially depression, were related to the chronic pain in patients with PTSD, however, the causality of elevated pressure pain threshold was uncertain in this study. To understand more clearly the relation between affective symptoms and chronic pain, it will be necessary to control the other specific factors.

• Journal of applied mathematics & informatics
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• v.1 no.1
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• pp.1-12
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• 1994

We consider a single channel CSMA/CD system with D homogeneous stations and impeded buffer of infinite size. We find a sufficient condition for the model to be stable under the threshold control policy and derive the limiting distri-bution of the number of messages in the system at the moment of service completion. We also derive the limiting distributing of the number of messages in the system size at arbitrary time by using Markov regenerative processes. Some numerical examples and special cases are also treated.

• Journal of IKEEE
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• v.9 no.2 s.17
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• pp.123-135
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• 2005

3GPP RLC protocol specification adopted a window-controlled selective-repeat ARQ scheme for provisioning reliable data transmission. Inevitably, the re-ordering issue arises in the 3GPP's ARQ since it belongs to the selective-repeat ARQ clan. A long re-ordering time results in the degradation of throughput and delay performance, and may invoke the overflow of the re-ordering buffer. Also, the re-ordering time must be regulated to meet the requirements of some services which are both loss-sensitive and delay-sensitive. In the 3GPP's ARQ, we may deflate the occupancy of the re-ordering buffer by reducing the window size and/or length of the status report period. Such a decrease, however, deteriorates the throughput and delay performance and encroaches the resource of the reverse channel. Aiming at reducing the occupancy at the re-ordering buffer while suppressing the degradation of throughput and delay performance, we propose threshold-dependent occupancy control schemes, identified as post-threshold and pre-threshold schemes, as supplements to the 3GPP's ARQ. For judging the effectiveness of the proposed schemes, we investigate peak occupancy, maximum throughput and average delay in the practical environment involving fading channels. From the simulation results, we observe that the proposed schemes invoke the performance trade-off between occupancy and throughput in general. Also, we reveal that the post-threshold scheme is able to improve the throughput and delay performance of the ordinary 3GPP's ARQ without inflating the occupancy of the re-ordering buffer.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.1
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• pp.334-349
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• 2022

The effectiveness of Wi-Fi networks is greatly influenced by the optimization of contention window (CW) parameters. Unfortunately, the conventional approach employed by IEEE 802.11 wireless networks is not scalable enough to sustain consistent performance for the increasing number of stations. Yet, it is still the default when accessing channels for single-users of 802.11 transmissions. Recently, there has been a spike in attempts to enhance network performance using a machine learning (ML) technique known as reinforcement learning (RL). Its advantage is interacting with the surrounding environment and making decisions based on its own experience. Deep RL (DRL) uses deep neural networks (DNN) to deal with more complex environments (such as continuous state spaces or actions spaces) and to get optimum rewards. As a result, we present a new approach of CW control mechanism, which is termed as contention window threshold (CW_Threshold). It uses the DRL principle to define the threshold value and learn optimal settings under various network scenarios. We demonstrate our proposed method, known as a smart exponential-threshold-linear backoff algorithm with a deep Q-learning network (SETL-DQN). The simulation results show that our proposed SETL-DQN algorithm can effectively improve the throughput and reduce the collision rates.

• Biomolecules & Therapeutics
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• v.6 no.1
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• pp.20-24
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• 1998

In the present study, we tested whether lead intoxication induces change of the thiamine content and the seizure threshold in rats and the changes of seizure threshold are related to the changes of thiamine status. It was also tested whether administration of excessive thiamine could reverse the toxic manifestation of lead in rats. Four groups of Wistar rats were prepared: 1) control group, 2) lead treated group, 3) lead plusthiamine treated group, and 4) thiamine deficient group. Each group of animals was divided into three subgroups based on age: 3, 7 and 16 weeks. In each group, thresholds of electroshock seizure and thiamine contents in brain regions including telencephalon, brain stem, cerebellum were measured. Thiamine contents in brain regions of the lead treated group were significantly lower than those of the control group and thiamine treatment reversed the decrease back to the control level. Thresholds of the electroshock seizure of the lead treated group in 3, 7 week old rats and those of thiamine deficient group in 3 week old rats were significantly lower than those of the control group. These observations were reversed by the supplementation with thiamine. These results from the present study suggest that increased seizure sensitivity induced by lead intoxication in rats may be mediated at least in part through the changes of thiamine status.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.65-68
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• 2003

3GPP's RLC protocol specification adopted an error control scheme based on selective repeat ARQ. In 3GPP ARQ, distinctive windows are provide at transmitting and receiving stations so that those stations are prohibited to send or receive data PDU's out of window. An increase in window size enhances delay performance. Such an increase, however, raises the occupancy at reordering buffer, which results in a long reordering time. Aiming at suppressing the occupancy at reordering buffer, we propose a occupancy control scheme in this paper. In this scheme, a threshold is created in the receiving station's window and a data PDU out of the threshold (but within the window) is treated according to go back N ARQ. By the employment of the occupancy control scheme, the occupancy at the reordering buffer is apparently reduced, while the delay performance may be degraded due to the properties of go back N ARQ. We, thus, investigate the peak occupancy and mean delay performance by a simulation method. From numerical examples, we observe a trade-off in both performance measures and conclude that the peak occupancy is effectively reduced by setting a proper threshold under a constraint on mean delay performance.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.96-96
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• 1995

It was recognized that lead intoxication reduces thiamine content in the brain of rat and this change produces the alterations of thiamine-related biochemical reactions. In the present study, it was tested whether the changes of myelin composition as well as seizure threshold induced by lead intoxication in rats may be related to these changes of thiamine status and thiamine related biochemical factors. Wistar rats were divided into five groups: Control group, Lead-treated group, Lead plus Thiamine-treated group, Thiamine-deficient group, Pyrithiamine-treated group. Each group was divided into three subgroups: 3, 7 and 16 week old group. Myelin protein and phospholipid, one of the compositions of myelin lipid, were measured in the myelin isolated from rat brain. Threshold of electric shock seizure was tested in each group. The amount of each myelin composition in lead-treated group and thiamine-deficient group was significantly lower than those of all the brains in control group, but recovery by supplementation with thiamine during lead intoxication was occurred only in the cerebellum of 3 week old animal. Thresholds of the electric shock seizure of lead treated group and thiamine deficient group in 3 and 7 week old rats were significantly lower than those of control group, while those of lead plus thiamine treated group were similar to those of control group.