• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1C
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• pp.59-68
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• 2002

In this paper we issue some problems occurring when a mobile host moves from a base station to another in a wireless multicasting and propose a solution. In the case of not being in the same multicast group, the old base station will pre-forward data to neighboring base stations to avoid transmission delay. However, if other mobile hosts move at short interval, the old base station may retransmit the same dta to the same neighboring base stations. Also, the old base station should retransmit data if the new base station has already discarded data even if the new base station is a member of the multicast group. In this paper we propose called Information Exchange Scheme (IES). In this scheme, each base station exchanges indirectly the data delivery information with the rest of the base stations in the same multicast group for efficient and reliable multicast and pre-forwards data not retransmitting the same data for minimizing transmission delay when a mobile host moves. We also present how IES is efficient by analyzing and simulating.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.247-256
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• 2002

In a wireless multicasting when a mobile host moves to the new bate station being in the same multicast group it needs to exchange information about data delivery between base stations to receive data from the new base station at once. However it is inefficient to use the existence schemes because it takes too much time to exchange information and many overheads. The next, a mobile host moving to the base station not being in the same multicast group, the old base station will pre-forward data to neighboring base stations to avoid transmission delay. However, if other mobile hosts move at short interval, the old base station may retransmit the same data to the same neighboring base stations. In this paper we proposed called Information Exchange Scheme (IES). In IES in the same multicast grope the base stations exchange information locally so it takes the minimum time and overheads to use IES. Also in IES the neighboring base stations delay to delete data for continuous moving of other MHs. We also present how our scheme is efficient by producing cost ad simulating.

• Korean Journal of Radiology
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• v.23 no.11
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• pp.1067-1077
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• 2022

Objective: To determine whether Sonazoid-enhanced ultrasound (SZUS) was noninferior to SonoVue-enhanced ultrasound (SVUS) in diagnosing hepatocellular carcinoma (HCC) using the same diagnostic criteria. Materials and Methods: This prospective, single-center, noninferiority study (NCT04847726) enrolled 105 at-risk participants (71 male; mean age ± standard deviation, 63 ± 11 years; range, 26-86 years) with treatment-naïve solid hepatic nodules (≥ 1 cm). All participants underwent same-day SZUS (experimental method) and SVUS (control method) for one representative nodule per participant. Images were interpreted by three readers (the operator and two independent readers). All malignancies were diagnosed histopathologically, while the benignity of other lesions was confirmed by follow-up stability or pathology. The primary endpoint was per-lesion diagnostic accuracy for HCC pooled across three readers using the conventional contrast-enhanced ultrasound diagnostic criteria, including arterial phase hyperenhancement followed by mild (assessed within 2 minutes after contrast injection) and late (≥ 60 seconds with a delay of 5 minutes) washout. The noninferiority delta was -10%p. Furthermore, different time delays were compared as washout criteria in SZUS, including delays of 2, 5, and > 10 minutes. Results: A total of 105 lesions (HCCs [n = 61], non-HCC malignancies [n = 19], and benign [n = 25]) were evaluated. Using the 5-minutes washout criterion, per-lesion accuracy of SZUS pooled across the three readers (72.4%; 95% confidence interval [CI], 64.1%-79.3%) was noninferior to that of SVUS (71.4%; 95% CI, 63.1%-78.6%), meeting the statistical criterion for non-inferiority (difference of 0.95%p; 95% CI, -3.8%p-5.7%p). The arterial phase hyperenhancement combined with the 5-minutes washout criterion showed the same sensitivity as that of the > 10-minutes criterion (59.0% vs. 59.0%, p = 0.989), and the specificities were not significantly different (90.9% vs. 86.4%, p = 0.072). Conclusion: SZUS was noninferior to SVUS for diagnosing HCC in at-risk patients using the same diagnostic criteria. No significant improvement in HCC diagnosis was observed by extending the washout time delay from 5 to 10 minutes.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.6
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• pp.1-7
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• 2012

Due to the increasing demand of network convergence, in future, hybrid/integrated satellite and terrestrial systems will play an important role. In that case, compatibilities between the satellite and terrestrial systems are very important for efficiency of the systems. 3GPP Long Term Evolution (LTE) is one of the 4G system. Therefore, in this paper, we introduce the design of interleaver for mobile satellite system based 3GPP LTE specification. The 4G system including the LTE specification adopted adaptive modulation and coding (AMC) schemes for efficient usage of resources, and the updating interval of resource allocation is an order of msec. However, because of the long round trip delay of satellite systems, we cannot employ the same AMC scheme specified for the terrestrial system, and thus it cannot effectively counteract to short term fadings. Therefore, in order to overcome these problems, we propose an interleaver scheme combined with AMC. We present the interleaver design results considering mobile satellite system based on the LTE and analyze the simulation results.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.1
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• pp.97-105
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• 2010

This paper proposes an effective medium access mechanism which is based on IEEE 802.11 to transmit an urgent message, The main features of the proposed mechanism are as follows. First, when it comes to channel access to have high priority, it has a shorter interval between frames than that specified in standard document. Second, we use fixed window size instead of back-off window with an exponential increase. Performance evaluation of proposed mechanism is executed by simulation and compare with the node using the specified mechanism in standard document. Performance evaluation results show that according to increasing competition the nodes using proposed method have less accessing time than the conventional methods. Also, the proposed method can improve processing time because of the decreasing transmission delay.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.3
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• pp.9-19
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• 2015

Internal air temperature of greenhouse is an important variable that can be influenced by the complex interaction between outside weather and greenhouse inside climate. This paper focuses on a data-based model approach to predict internal air temperature of the greenhouse. External air temperature, solar radiation, wind speed and wind direction were measured next to an experimental greenhouse supported by the Electronics and Telecommunications Research Institute and used as input variables for the model. Internal air temperature was measured at the center of three sections of the greenhouse and used as an output variable. The proposed model consisted of a transfer function including the four input variables and tested the prediction accuracy according to the sampling interval of the input variables, the orders of model polynomials and the time delay variable. As a result, a second-order model was suitable to predict the internal air temperature having the predictable time of 20-30 minutes and average errors of less than ${\pm}1K$. Afterwards mechanistic interpretation was conducted based on the energy balance equation, and it was found that the resulting model was considered physically acceptable and satisfied the physical reality of the heat transfer phenomena in a greenhouse. The proposed data-based model approach is applicable to any input variables and is expected to be useful for predicting complex greenhouse microclimate involving environmental control systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.235-243
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• 2012

In this paper, we propose a method to improve performance of pilot symbol assisted modulation(PSAM) channel estimation method for OFDM systems over frequency selective channel. When channel values are estimated, the low pilot density used for channel estimation increases not only the effective data rate but also power efficiency. Thus, the lower pilot density which is used for channel estimation is better for OFDM system. At first, we estimate the channel values which are located at the middle of adjacent pilots, and then all of the possible channel values are estiamted by using original pilot values and previously estimated pilot values. Furthermore, the error of estimated channel values is reduced by introducing guard interval which is designed acccording to maximum channel delay. Performance achieved with the proposed method is illustrated by simulation experiments in comparison with the existing methods in terms of mean squared error(MSE).

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.4
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• pp.515-519
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• 1999

With the purpose of determining the influence of sexual partners on the oestrous behaviour and to evaluate the accuracy of predicting the time from implant withdrawal to sexual receptivity following a treatment with Synchromate B (SMB), 15 adult Brahman cows were used in each of three phases. During phase I and n, random pairs of animals were induced to display oestrus one pair after the other at daily intervals, while in phase III, cows were induced alternately, every other day, one cow on the 1st day, two on the 3rd, one on the 5th, two on the 7th until all cows were treated. Sixty six percent of the cows in phases I and II, and 80% in phase III came into oestrous after treatment. The interval between implant withdrawal and, expected and observed oestrous was statistically different in all phases. Clustering of oestrous was evident. Cows displayed sexual receptivity within a. range of -24 to +96; -24 to +72 and -216 to +192 hours after implant withdrawal for the three phases, respectively, with a tendency for cows treated first (within treatments), to delay their oestrus signs and vice versa. In phase III, four cows showed oestrous behaviour with the implant in place. These in spite of not observing pre-ovulatory follicles. Correlation values of 0.99, 0.93 and 0.90 (P<0.05) were found respectively among treatments, between the number of cows coming into oestrus and the number of mounts observed. These findings suggest that there are social and behavioural factors in a herd that may override exogenous synchronisation treatments.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.6
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• pp.669-675
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• 2014

In this paper, we described the investigated theoretical time synchronization performances and experiment results obtained by commercially provided PTP (Precise Time Protocol) modules when the time of a slave clock is synchronized to the master clock. In the case of the theoretical performance analysis, we investigated 3 types of clock levels such as Crystal Oscillator (XO), TCXO (Temperature Compensated XO) and OCXO (Oven Controlled XO). From the analysis, it was observed that the synchronization performance is greatly influenced by the synchronization period and the required performance under 1 us can be achieved by using XO level clocks when the synchronization period is less than 2 seconds and the uncertainty of the propagation delay is under 100 ns. For the experiments using commercial PTP modules, the synchronization performance was investigated for direct, through 1 hub and through 2 hubs connections between the master clock and the slave clock. From the experiment results, we observed that time synchronization under 90 ns with 1,000 seconds observation interval can be achieved in the case of direct connection.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.16 no.1
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• pp.12-20
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• 1994

Generally, the totally paralyzed face can never be made normal by any of the current methods of reconstruction. Careful selection of patients based on sound judgment of what can and cannot be achieved by the proposed surgical technique is paramount to a successful operation and a satisfied patient. The results are related to time of delayed between injury and repair ; the shorter the delay the better are the results. The objectives in correcting facial paralysis are to achieve normal appearance at rest ; symmetry with voluntary motion ; control of the ocular, oral, and nasal sphincter ; symmetry with involuntary emotion and controlled balance when expressing when expressing emotion ; and no significant functional deficit secondary to the reconstructive surgery. It must be employed a number of concepts, for treatment of the paralyzed face by surgeon, depending on the cause, time interval, and wound characteristics, as well as the availability of and necessity for neuromuscular substitution. Nerve grafts, crossovers, muscle transfers, free muscle and nerve-muscle grafts, micronuerovascular muscle transfers, and regional muscle transposition are the principal methods being developed. We applied the temporal musle transposition for reanimation of unilatrally paralyzed faces for long times on two patients. The results of muscle transposition can be enhanced by the patient's learning to activate the transposed muscle by voluntary effort, and are best in patients who are motivated to learn the necessary motor-sensory coordination techniques.