• Journal of Periodontal and Implant Science
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• v.28 no.2
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• pp.263-273
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• 1998

For histologic observation of the regenerated bone following guided tissue regeneration (GTR) using ePTFE membranes with calcium carbonate implant and autogenous bone graft, biopsies were collected from 2 patients during 5-year-postoperative surgical reentry. In both combined cases with guided tissue regeneration in conjunction with calcium carbonate implant and autogenous bone graft, significant bone fill and gain in probing attachment level was observed. In histologic examination, specimen in GTR case with calcium carbonate grafting was composed of a dense bone containing vascular channel with lamellar structure and viable bone cells in lacunae, however considerable calcium carbonate particles remained unresorbed and isolated from regenerated bone by the dense cellular and fibrous connective tissue. No formative cells could be seen in contact with remained calcium carbonate particles. In GTR case with autogenous bone grafting, specimen show was composed of a dense lamellar bone containing vascular channel, which showed normal alveolar bone architectures. The present observation indicate that guided tissue regeneration in conjunction with grafting, especially autogenous bone graft, has highly osteogenic potential, however resorbable calcium carbonate granules were not completely resorbed at 5 year postimplantation.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.4 s.304
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• pp.45-50
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• 2005

In digital hearing aid system, one of the main problems is acoustic feedback which is known as howling because of miniaturization md high-gain amplification. In this paper, we proposed a feedback cancellation algorithm for hearing aid using time delay and time-varying decorrelation filter. The proposed algorithm has a kind of adaptive filter structure, which is combined with time delay and time-varying decorrelation filter to improve feedback cancellation. An all pass filter was implemented as the time-varying decorrelation filter using low frequency modulator. From the result of computer simulation, it is verified that the proposed algorithm has good ability to cancel feedback.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.8
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• pp.1899-1906
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• 1998

In ATM switching system link bandwidth is one of the improtant resources. Thus ATM switching system must allocate the bandwidth to the users efficiently and guarantee the QoS. Especially to guarantee the QoS of the VBR traffic source such as video, users must declare the traffic characteristics and QoS expectations using UPC parameters. The CAC can use two multiplexig models in variation to link capacity and connection number. One is loseless multiplexing model; the second is a statistical multiplexing model. The loseless multiplexing model performs best when the number of mutiplexed sources is small, but as the number of multiplexed sources is increase the CAC must use the statistical multiplexing model. In this paper, the statistical multiplexing models are studied, which are suitable for high capacity ATM link on VBR traffic sources. The satistical multiplexing model and the loseless multiplexing model are combined. In statistical model we map the UPC parameters provided by new VBR connection to appropriate source traffic model. In the high capacity ATM link, as the connection number increases, the statical multiplexing gain increases.

• Korean Journal of Agricultural Science
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• v.44 no.1
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• pp.77-85
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• 2017

A total of 120 weaning pigs [(Landrace ${\times}$ Yorkshire) ${\times}$ Duroc] with an average body weight of $8.95{\pm}0.88kg$ were used in this study to investigate the influence of supplementation of combined flavor and sweetener. The diets included: 1) TRT1, basal diet, 2) TRT2, TRT1 + 500 mg/kg flavor, 3) TRT3, TRT1 + 150 mg/kg sweetener, and 4) TRT4, TRT1 + 500 mg/kg flavor + 150 mg/kg sweetener. The TRT4 treatment produced a higher average daily gain (ADG) than that in the other treatments on d 0 - 14 and the whole experimental period (p < 0.05). The TRT1 and TRT2 treatments gave a lower average daily feed intake (ADFI) than that of TRT4 on d 0 - 14 and d 0 - 42 (p < 0.05). On d 15 - 42, TRT4 had a higher ADFI than that of TRT1 (p < 0.05). Compared to TRT1, dry matter (DM), gross energy (GE), and nitrogen (N) digestibility increased in pigs fed the TRT4 diet (p < 0.05) on d 14. Serum norepinephrine concentration in TRT1 treatment was higher (p < 0.05) than that in TRT4 treatment at 72 h after weaning. On d 0 - 7, diarrhea score decreased in TRT4 treatment compared with TRT1 and TRT2 treatments. In conclusion, flavor and sweetener complex addition improved ADG and ADFI as well as DM, N, and GE digestibility in weanling pigs. This supplementation in pigs' diets decreased the serum norepinephrine concentration at 72 h after weaning and the diarrhea score during the first week of weaning.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.818-823
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• 2016

Millimeter wave (mm-wave) communication systems provide high data rates owing to the large bandwidths available at mm-wave frequencies. Recently, analogue and digital combined beamforming, namely "hybrid beamforming" has drawn attentions owing to its ability to realize the required link margins in mm-wave systems. Taking into account the radio frequency (RF) hardware limitations, such as the analogue phase shifter gain constraint and the low resolution of the phase controller, we introduce an uplink hybrid beamforming system that includes discrete Fourier transform (DFT) based "fixed" analogue beamforming. We adopt a zero-forcing (ZF) multiple-input multiple-output (MIMO) equalizer to eliminate the uplink inter-user interferences. Moreover, to improve the sum-rate performances, we propose a transmit beam selection algorithm which makes the uplink effective channels, i.e., the beamformed channels, become near orthogonal. The effectiveness of the proposed beam selection algorithm was verified through numerical simulations.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.40
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• pp.3.1-3.8
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• 2018

Background: In this research article, we evaluate the use of sub-periosteal tunneling (tunnel technique) combined with alloplastic in situ hardening biphasic calcium phosphate (BCP, a compound of β-tricalcium phosphate and hydroxyapatite) bone graft for lateral augmentation of a deficient alveolar ridge. Methods: A total of 9 patients with deficient mandibular alveolar ridges were included in the present pilot study. Ten lateral ridge augmentation were carried out using the sub-periosteal tunneling technique, including a bilateral procedure in one patient. The increase in ridge width was assessed using CBCT evaluation of the ridge preoperatively and at 4 months postoperatively. Histological assessment of the quality of bone formation was also carried out with bone cores obtained at the implant placement re-entry in one patient. Results: The mean bucco-lingual ridge width increased in average from 4.17 ± 0.99 mm to 8.56 ± 1.93 mm after lateral bone augmentation with easy-graft CRYSTAL using the tunneling technique. The gain in ridge width was statistically highly significant (p = 0.0019). Histomorphometric assessment of two bone cores obtained at the time of implant placement from one patient revealed 27.6% new bone and an overall mineralized fraction of 72.3% in the grafted area 4 months after the bone grafting was carried out. Conclusions: Within the limits of this pilot study, it can be concluded that sub-periosteal tunneling technique using in situ hardening biphasic calcium phosphate is a valuable option for lateral ridge augmentation to allow implant placement in deficient alveolar ridges. Further prospective randomized clinical trials will be necessary to assess its performance in comparison to conventional ridge augmentation procedures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1A
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• pp.50-58
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• 2008

The use of space-division multiple access(SDMA) in the downlink of multiuser multi-input/multi-output(MIMO) wireless transmission systems can provide substantial gains in system throughput. When the channel state information(CSI) is available at the transmitter, a considerable performance improvement can be attained by adapting the transmission rates to the reported CSI. In addition, to combat frequency selective fadings in wideband wireless channels, bit-interleaved coded OFDM(BIC-OFDM) modulation schemes are employed to provide reliable packet delivery by utilizing frequency diversity through channel coding. In this paper, we propose an adaptive modulation and coding(AMC) scheme combined with an opportunistic scheduling technique for the MIMO BIC-OFDM with bandwidth-limited feedback channels. The proposed scheme enhances the link performance by exploiting both the frequency diversity and the multiuser diversity. To reduce the feedback information, the proposed AMC scheme employs rate adaptation methods based on an OFDM symbol rather than on the whole subchannels. Simulation results show that the proposed scheme exhibits a substantial performance gain with a reasonable complexity over single antenna systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12C
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• pp.997-1005
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• 2008

In this paper, we proposed advanced T-DMB system which is based on Eureka-147 using UEP coding methods and hiererchical modulation for providing additional services while maintaining BER performance. We simulated the proposed advanced T-DMB system using unequal l6QAM modulation scheme combined with various bit split methods and coding methods such as double binary turbo code of DVB-RCS standard and LDPC code of DVB-S2 standard. In the simulation results, double binary turbo code and LDPC code of proposed advanced T-DMB system have coding gain of 2dB and 3.5dB compared to conventional T-DMB system respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.3
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• pp.273-279
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• 2009

In this paper, an antenna which has dipole-like radiation pattern and low profile is proposed. The antenna is composed of four elements slot array based on L-shaped 0.43 $\lambda_g$ slot element. It presents a omni-directional radiation patter in the azimuth plane and has a null toward broad-side direction. In the design, a small mono-pole antenna which acts as a large capacitance element, combined with the partially removed ground plane by four L-shaped slots. As a result, these structure act as a LC resonator for radiation. The measured result shows, the impedance bandwidth(VSWR$\leq$2) of the proposed antenna is 60 MHz(2.35$\sim$2.41 GHz). The measured maximum radiation gain and efficiency of proposed antenna is 0.02 dBi, 56.7 % at center frequency 2.38 GHz, respectively. The proposed antenna can be applied to wireless tan access point system.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.5
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• pp.344-352
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• 2020

Covertness and performance are very important design goals in the underwater communications. To satisfy both of them, we proposed efficient underwater communication model which combined multiband and direct sequence spread spectrum method in order to improve performance and covertness simultaneously. Turbo coding method with 1/3 coding rates is used for channel coding algorithm, and turbo equalization method which iterately exchange probabilistic information between equalizer and decoder is used for receiver side. After optimal threshold value was set in Rake processing, this paper analyzed the performance by varying the number of chips were 8, 16, 32 and the number of bands were from 1 to 4. Through the simulation results, we confirmed that the performance improvement was obtained by increasing the number of bands and chips. 2~3 dB of performance gain was obtained when the number of chips were increased in same number of bands.