• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.637-644
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• 2004

This paper proposed and implemented the adaptive transmission middleware for video streaming, which is able to support the adaptive transmission of video data to the fluctuating changes of network environment in the packet-based network and the properties of transmitted video data. The adaptive transmission middleware is made up SR-RTP-based transfer module and TFRC(TCP Friendly Rate Control)-based transfer-rate control module. The SR-RTP-based transfer module supports RTP-based real-time transfer of video data and packet retransmission scheme retransmitting the high-priority packets selectively in the damaged video data to reduce the error induced by the packet loss. Sharing the transmission bandwidth of network with the TCP-based data transfer, the TFRC-based transfer-rate control module controls the transfer rate of video data according to the most allowable transmission bandwidth in the network, so that the transfer rate is controlled adaptively to the fluctuating changes of transmission bandwidth. This paper, for the experiment, applied the adaptive transmission middleware to video streaming in the external Internet environment, and analyzed the effective frame transfer rate and the degree of the streaming jitter to evaluate the performance of packet-loss recovery and adaptive transfer rate control. In the external Internet environment where the packet-loss rate is high a bit, the relatively high streaming performance was showed compared with the case that didn't apply the adaptive transmission middleware.

• ETRI Journal
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• v.45 no.6
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• pp.974-981
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• 2023

This paper presents a transition-limited pulse-amplitude modulation (TLPAM) signaling method to enable a high data rate and robust wireline communications. TLPAM signaling addresses the impact of high intersymbol interference (ISI) ratios in conventional M-ary PAM signaling methods by limiting the maximum voltage transition level between adjacent symbols. The implementation of a TLPAM signaling encoder is realized by setting back the most significant bits (MSBs) in the queue. The correlation between TLPAM's maximum transition level, effective data rate, and eye width/height is analyzed with various channel loss parameters, followed by characterization and measurement results with a realistic channel setup. The analysis and experimental results reveal the effectiveness of the proposed TLPAM signaling scheme for achieving a high data rate with minimal interference.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1195-1204
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• 2002

We calculated dose rate using radiative transfer equations to consider radiative processes distinctly. The dose rate at Pohang(36°02'N, 129°23'E) was calculated using measured ozone and meteorological data and two-stream approximations(quadrature, Eddington, delta Eddington, PIFM(practical improved flux method), discrete ordinate, delta discrete ordinate) are used in solving equation. The purpose of this study is to determine the most compatible radiative transfer approximation for simulating the radiative and photochemical processes of atmosphere through comparision between calculated and measured values. Dose rate of the biologically effective irradiance in the region 0.28-0.32 U m showed the highest value when quadrature and Eddington was used and lower value on condition that delta scaling was applied. Correlation coefficient between dose rate at surface using radiation transfer equation and measured UV-B at Pohang was 0.78, 0.79 and 0.81 when delta Eddington, PIFM and delta discrete ordinate were used. Also, in case of above approximations were used, MBE(Mean Bias Error) was within -0.3MED/30min and RMBE(Relative Mean Bias Error) was below 10% between 1200 LST and 1400 LST Approximations which are compatible in estimating radiative process are delta Eddington, PIFM and delta discrete ordinate. Especially, in case that radiative process is considered more detail, delta discrete ordinate increased the number of stream is proper.

• Journal of Power Electronics
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• v.16 no.2
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• pp.805-814
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• 2016

Electric-field coupled power transfer (ECPT) systems have been proposed as an alternative wireless power transfer (WPT) technology in recent years. With the use of capacitive plates as a coupling structure, ECPT systems have many advantages such as design flexibility, reduced volume of the coupling structure and metal penetration ability. In addition, wireless communications are effective solutions to improve the safety and controllability of ECPT systems. This paper proposes a power and signal shared channel for electric-field coupled power transfer systems. The shared channel includes two similar electrical circuits with a band pass filter and a signal detection resistor in each. This is designed based on the traditional current-fed push-pull topology. An analysis of the mutual interference between the power and signal transmission, the channel power and signal attenuations, and the dynamic characteristic of the signal channel are conducted to determine the values for the electrical components of the proposed shared channel. Experimental results show that the designed channel can transfer over 100W of output power and data with a data rate from 300bps to 120 kbps.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.6
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• pp.72-84
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• 1988

Engine performance is one of the main objectives specified at the beginning of a new engine design project. The cycle simulation for SI engine is based on the zero-dimensional gas exchange model and a heat release expression by Viebe. This program also requires minimum input data and takes only a short time to run. Heat transfer from cylinder transfer formula. The flow coefficient (effective area) is calculated from valve lift using the standard flow coefficient curve and engine friction is calculated from the Millington and Hartles' engine friction formula. The chemical species considered in burned gas are 6 species CO, CO, H$_{2}$, H$_{2}$O, $O_{2}$, N$_{2}$ and the cylinder pressure, homogeneous cylinder temperature, gas composition and burned fraction are calculated at each crank angle through the cycle. To check the validity and accuracy, experimental study was done with 3 engines for measuring cylinder pressure, indicated mean effective pressure, brake mean effective pressure and air flow rate, etc. Despite its simple assumptions, cycle simulation showes excellent breathing and performance correlation when compared with data of tested engines, and have been proved useful in engine design.

• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.183-189
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• 2004

The flow and the heat transfer about the cross-flow fin-tube heat exchanger in an out-door unit of a heat pump system has been numerically Investigated. Using the general purpose analysis code, FLUENT, the Navier-Stokes equations and the energy equation are solved for the three dimensional computation domain that encompasses multiple rows of the fin-tube. The temperature on the fin and tube surface is assumed constant but compensated later through the fin efficiency when predicting the heat-transfer rate. The contact resistance is also taken into consideration. The flow and temperature fields for a wide range of inlet velocity and fin-tube arrangements are examined and the results are presented in the paper. The details of the flow are very well captured and the heat transfer rate for a range of inlet velocity is in excellent agreement with the measured data. The flow solution provides the effective permeability and the inertial resistance factor of the heat exchanger if the exchanger were to be approximated by the porous medium. This information is essential in carrying out the global flow field calculation which, in turn, provides the inlet velocity lot the microscopic temperature-field calculation of the heat exchanger unit.

• Food Science and Biotechnology
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• v.18 no.5
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• pp.1293-1297
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• 2009

In this study, drying kinetics of onion slices was examined in a laboratory scale vacuum dryer at an air temperature in a range of $50-70^{\circ}C$. Moisture transfer from onion slices was described by applying the Fick's diffusion model, and the effective diffusivity was calculated. Temperature dependency of the effective diffusivity during drying process obeyed the Arrhenius relationship. Effective diffusivity increased with increasing temperature and the activation energy for the onion slices was estimated to be 16.92 kJ/mol. The experimental drying data were used to fit 9 drying models, and drying rate constants and coefficients of models tested were determined by non-linear regression analysis. Estimations by the page and Two-term exponential models were in good agreement with the experimental data obtained.

• The Korean Journal of Emergency Medical Services
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• v.23 no.1
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• pp.113-123
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• 2019

Purpose: The aim of this study was to provide basic data to improve the survival rate of pre-hospital cardiac arrest patients. This study suggests a more effective method of performing effective chest compressions for a cardiac arrest patient in a moving ambulance. Methods: To compare the differences between gender and license (qualification), SPSS 18.0 (Windows) was used. Independent and paired t-tests were used for differences between before and after wearing a rescuer's belt. Results: The success rate of chest compressions according to gender was higher in males ($68{\pm}21.91%$) than in females ($25.04{\pm}16.88%$). There was no difference according to license ($44.70{\pm}26.63$ for paramedic, $45.05{\pm}19.25$ for nurse). However, the depth (mm) and the success rate (%) were improved during the evaluation of chest compressions when wearing the rescuer's belt (depth: $46.95{\pm}6.49$ vs. $49.55{\pm}6.05$, success rate: $44.80{\pm}24.66$ vs. $57.39{\pm}26.823$). Conclusion: Wearing a rescuer's belt in an ambulance during patient transport can result in deeper and more accurate chest compressions; therefore, it is expected to be effective in recovering the circulation of patient with cardiac arrest.

• Journal of Biomedical Engineering Research
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• v.39 no.5
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• pp.213-219
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• 2018

Stomach cancer is the most diagnosed cancer in Korea. When gastric cancer is detected early, the 5-year survival rate is as high as 90%. Gastroscopy is a very useful method for early diagnosis. But the false negative rate of gastric cancer in the gastroscopy was 4.6~25.8% due to the subjective judgment of the physician. Recently, the image classification performance of the image recognition field has been advanced by the convolutional neural network. Convolutional neural networks perform well when diverse and sufficient amounts of data are supported. However, medical data is not easy to access and it is difficult to gather enough high-quality data that includes expert annotations. So This paper evaluates the efficacy of transfer learning in gastroscopy classification and diagnosis. We obtained 787 endoscopic images of gastric endoscopy at Gil Medical Center, Gachon University. The number of normal images was 200, and the number of abnormal images was 587. The image size was reconstructed and normalized. In the case of the ResNet50 structure, the classification accuracy before and after applying the transfer learning was improved from 0.9 to 0.947, and the AUC was also improved from 0.94 to 0.98. In the case of the InceptionV3 structure, the classification accuracy before and after applying the transfer learning was improved from 0.862 to 0.924, and the AUC was also improved from 0.89 to 0.97. In the case of the VGG16 structure, the classification accuracy before and after applying the transfer learning was improved from 0.87 to 0.938, and the AUC was also improved from 0.89 to 0.98. The difference in the performance of the CNN model before and after transfer learning was statistically significant when confirmed by T-test (p < 0.05). As a result, transfer learning is judged to be an effective method of medical data that is difficult to collect good quality data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.9A
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• pp.2249-2257
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• 1998

In this paper, we propose the enhanced priority control algorithm that adaptively controls the cell service ratio according to the relative cell occupancy ratio of buffer. The asynchronous transfer mode (ATM) provides the means to support various multimedia services in broadband networks. To support multimedia services, various data traffics of different priorities should be controlled effectively. And also it needs congestion control functions required in the netowrk to carry out the control operation. To accomplish this in a flexible and effective manner, priority classes for the different services ar ecommonly used. The proposed enhanced priority control mechanism have two service calsses of the delay sensitive class and the loss sensitive class. The simulation results show that te proposed control mechanism improves the QoS, the charateristics of cell loss probability and mean cell delay time, by selecting propeor relativ ecell occupancy ratio of buffer and the average arrival rate.