• Proceedings of the IEEK Conference
• /
• summer
• /
• pp.23-26
• /
• 2004

Five-port reflectometer which consists of a ring with 5 arms (two inputs, three outputs) and three RF power detectors has been used as a vector network analyser, a demodulator in the homodyne receiver as well as in Phase Looked Loop (PLL) and so on. Calibration of five-port reflectometer is an important task. In this paper, we present a calibration method of five-port for a propagation channel sounder. The method is based on measurement of the phase differences between the three voltages at the five-port's outputs in order to determine the ratio of two input incident waves. The frequency channel sounder based on five-port is calibrated for each frequency from 2.2 GHz to 2.6 GHz with 1 MHz step. This method can also determine the absolute delays of each propagation path in the propagation channel. The calibration method is validated using measurement data.

• Experimental and Molecular Medicine
• /
• v.50 no.11
• /
• pp.4.1-4.13
• /
• 2018

Two-pore domain $K^+$ (K2P) channels have been shown to modulate neuronal excitability. The physiological role of TWIK-1, the first identified K2P channel, in neuronal cells is largely unknown, and we reported previously that TWIK-1 contributes to the intrinsic excitability of dentate gyrus granule cells (DGGCs) in mice. In the present study, we investigated the coexpression of TWIK-1 and TASK-3, another K2P member, in DGGCs. Immunohistochemical staining data showed that TASK-3 proteins were highly localized in the proximal dendrites and soma of DGGCs, and this localization is similar to the expression pattern of TWIK-1. TWIK-1 was shown to associate with TASK-3 in DGGCs of mouse hippocampus and when both genes were overexpressed in COS-7 cells. shRNA-mediated gene silencing demonstrated that TWIK-1/TASK-3 heterodimeric channels displayed outwardly rectifying currents and contributed to the intrinsic excitability of DGGCs. Neurotensin-neurotensin receptor 1 (NT-NTSR1) signaling triggered the depolarization of DGGCs by inhibiting TWIK-1/TASK-3 heterodimeric channels, causing facilitated excitation of DGGCs. Taken together, our study clearly showed that TWIK-1/TASK-3 heterodimeric channels contribute to the intrinsic excitability of DGGCs and that their activities are regulated by NT-NTSR1 signaling.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.3B
• /
• pp.226-236
• /
• 2002

In this paper, we present the channel assignment and management methods for an efficient use of traffic channel resource for supporting 12.2 Kbps, 64 Kbps, and 384 Kbps traffic with the different quality of service (QoS) in the radio network controller (RNC) in asynchronous IMT-2000 system. We first describe two types of traffic channel block assignments for utilizing the traffic channel efficiently; the partially dedicated and partially shared channel (PDPSC) assignment and the completely shared channel (CSC) assignment. The former is that some traffic channel block is completely assigned to each traffic type and the other blocks are shared with some traffic type. The latter is that all traffic channel blocks are completely shared with all traffic types. Further, for efficiently assigning, releasing, and managing the channel resource, we present the traffic channel management method which consists of the block and task management step. Through numerical examples, we evaluate the blocking probability and the mean number of required search for fading the available channel when applying our proposed channel block assignment and resource management methods.

• Health Policy and Management
• /
• v.8 no.1
• /
• pp.112-134
• /
• 1998

The purpose of this study is to analyze the community participation in regional health planning by using the operational definition of participation channels, and to find out the significant variables of community participation channel which are highly related to the scores of regional health plan. The channels we adopted for the study are recommended in the guidebook for regional health planning. They are performing residents' helath survey, submitting written agreement of publics, holding public hearings, putting publicnotice, conducting community health committee meeting, submitting opinion of chambers and Mayors, and operating task-force for planning. We analyzed the selected data of 8 community participation channels, which were submitted by 141 rural health centers for the pursuit of governmental subsidy in 1997. The major findings of this study are as follows; 1. In the process of regional health planning, 88.7% of rural community health centers have performed the residents' health survey, 14.9% submitted written agreement of publics, 11.3% held public hearings, 39.0% put public notice, 46.8% conducting community health committee meeting, 48.9% submitted opinion of chambers, 61.7% submitted opinion of Mayors and 25.5% operated task-force for planning. The result shows that most of community participation channels have been utilized at very low rates, except the residents' health survey. 2. We have analyzed the impact of these community participation channels on the regional health plan scores. In the multiple regression model, we set the regional health plan score as the dependent variable., and the use of participation channels as the idependent variables(1 if the channels are used, 0 otherwise). Finally, the regression analyses show that two channel variables, opinion of chambers and public notice, were the significant positive channel variables on the score of community health plan.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.12
• /
• pp.2349-2356
• /
• 2008

In this paper, we present the method to effectively extract and classify the EEG caused by only brain activity when a normal subject is in a state of mental activity. We measure the synchronous EEG on the auditory event when a subject who is in a normal state thinks of a specific task, and then shift the baseline and reduce the effect of biological artifacts on the measured EEG. Finally we extract only the mental task signal by averaging method, and then perform the recognition of the extracted mental task signal by computing the AR coefficients. In the experiment, the auditory stimulus is used as an event and the EEG was recorded from the three channel $C_3-A_1$, $C_4-A_2$ and $P_Z-A_1$. After averaging 16 times for each channel output, we extracted the features of specific mental tasks by modeling the output as 12th order AR coefficients. We used total 36th order coefficient as an input parameter of the neural network and measured the training data 50 times per each task. With data not used for training, the rate of task recognition is 34-92 percent on the two tasks, and 38-54 percent on the four tasks.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.16 no.2
• /
• pp.27-33
• /
• 2020

Backward compatibility is one of the key issues for radio equipment supporting IEEE 802.11, the typical wireless local area networks (WLANs) communication protocol. For a successful packet decoding with the backward compatibility, the frame format detection is a core precondition. This paper presents a novel frame format detection method based on a deep learning procedure for WLANs affiliated with IEEE 802.11. Considering that the detection performance of conventional methods is degraded mainly due to the poor performances in the symbol synchronization and/or channel estimation in low signal-to-noise-ratio environments, we propose a novel detection method based on convolutional neural network (CNN) that replaces the entire conventional detection procedures. The proposed deep learning network provides a robust detection directly from the receive data. Through extensive computer simulations performed in the multipath fading channel environments (modeled by Project IEEE 802.11 Task Group ac), the proposed method exhibits superb improvement in the frame format detection compared to the conventional method.

• Journal of Ocean Engineering and Technology
• /
• v.16 no.6
• /
• pp.71-75
• /
• 2002

In this paper, a study on the principal performance of the purse seiner ship in two vessel formations was conducted. For this task, the outline of the purse seiner fishing system in two vessel formations was reviewed. At the same time, based on the general arrangement plan, hull from of the main vessel was developed. And the stability and ship motion characteristics of the ship design were estimated. Finally, to verify the characteristics of the resistance and self-propulsion coefficient, a model test in a circulating water channel was performed. As n result, it is anticipated that this presentation will be used as the foundation material for research of purse seiner.

• Water Engineering Research
• /
• v.1 no.2
• /
• pp.95-105
• /
• 2000

A method is presented which enables easily the computation of the suspended sediment discharge as the mean sediment concentration and mean flow velocity. This method has significant advantages over the traditional method, which principally depend on a set of measured concentration data. The method is based on both a new sediment concentration and mean sediment concentration equations which have been derived from the entropy concept used in statistical mechanics and information theory: (1) The sediment concentration distribution equations derived, are capable of describing the variation of the concentration in the vertical direction. (2) The mean concentration equation derived, is capable of calculating easily the mean concentration by using only one measured concentration in open channel. The present study mainly addresses the following two subjects : (1) new sediment concentration and mean sediment concentration equations are derived from the entropy concept : (2) An efficient and useful method of suspended sediment-discharge measurements is developed which can facilitate the estimation of suspended sediment-discharge in open channel. Flume and laboratory data are used to carry out the research task outlined above. An efficient method for determining the suspended sediment-discharge in the open channel has been developed. The method presented also is efficient and applicable in estimating the sediment transport in rivers and the sediment deposit in the reservoirs, and can drastically reduce the time and cost of sediment measurements.

• Speech Sciences
• /
• v.11 no.1
• /
• pp.7-20
• /
• 2004

In this paper, we propose a two-step noise compensation algorithm in feature extraction for achieving robust speech recognition. The proposed method frees us from requiring a priori information on noisy environments and is simple to implement. First, in frequency domain, the Harmonics-based Spectral Subtraction (HSS) is applied so that it reduces the additive background noise and makes the shape of harmonics in speech spectrum more pronounced. We then apply a judiciously weighted variance Feature Vector Normalization (FVN) to compensate for both the channel distortion and additive noise. The weighted variance FVN compensates for the variance mismatch in both the speech and the non-speech regions respectively. Representative performance evaluation using Aurora 2 database shows that the proposed method yields 27.18% relative improvement in accuracy under a multi-noise training task and 57.94% relative improvement under a clean training task.

• Korean Journal of Child Studies
• /
• v.36 no.6
• /
• pp.85-100
• /
• 2015

This study divided elementary school 6th graders of into a higher academic achievement group (n=19) and a lower academic achievement group (n=19) in order to examine the tendency of left and right hemisphere preferences, characteristics and relationships of learning ability factors by means of EEG. For this purpose, brain waves in performing higher cognitive tasks for 5 min. were measured with a two-channel (Fp1, Fp2) EEG measurement system and hemisphere preference was measured by means of a questionnaire. Our results were as follows. First, hemisphere preference indicated that the higher group showed a left hemisphere tendency and the lower group indicated a right hemisphere tendency. Second, the first learning ability test found that the higher group performed its task rapidly with higher levels of concentration and cognitive strength and lower loading and the lower group conducted its task more slowly with lower levels of concentration and cognitive strength and higher loading. The second test showed that the higher group performed its task rapidly with lower levels of concentration.