• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.3
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• pp.123-131
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• 2024

The dispute between SK and Netflix, which has been going on for more than three years, ended in the direction of dropping the lawsuit and establishing a cooperative relationship between the two companies. However, as Internet traffic usage is likely to increase further in the future due to digital transformation and activation of generated AI, conflicts between domestic mobile carriers and global CP operators over network usage fees can arise at any time. In this study, the issues of the dispute related to network usage fees that occurred between SK and Netflix were examined, and different implications were drawn for each issue. The cost and scope of network usage considerations are an issue that must be determined entirely by negotiations between operators. However, if a dispute occurs between operators, user damage such as speed delays may occur, so it is necessary to prepare a policy alternative. As the domestic media industry has grown cooperatively with global CPs, it is considered important to form a reciprocal relationship between domestic mobile telecommunication operators and global CP operators regarding network usage fees in the future.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.3
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• pp.221-235
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• 2024

Errors included in Global Navigation Satellite System (GNSS) measurements degrade the performance of user position estimation but can be mitigated by spatial correlation properties. Augmentation systems providing correction data can be broadly categorized into State Space Representation (SSR) and Observation Space Representation (OSR) methods. The satellite-based cm-level augmentation service based on the SSR broadcasts correction data via satellite signals, unlike the traditional Real-Time Kinematic (RTK) and Network RTK methods, which use OSR. To provide a large amount of correction data via the limited bandwidth of the satellite communication, efficient message structure design considering service area, correction generation, and broadcast intervals is necessary. For systematic message design, it is necessary to analyze the influence of error components included in GNSS measurements. In this study, errors in satellite orbits, satellite clocks for GPS, Galileo, BeiDou, and QZSS satellite constellations ionospheric and tropospheric delays over one year were analyzed, and their spatial decorrelations and linear modeling characteristics were examined.

• Journal of Internet Computing and Services
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• v.1 no.2
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• pp.29-37
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• 2000

Asynchronous transfer mode is flexible to support multimedia communication services using asynchronous time-sharing and statistical multimedia techniques to the existing data communication area, ATM ABR service controls network traffic using feedback information on the network congestion situation in order to guarantee the demanded service qualities and the available cell rates, In this paper we apply the control method using queue length prediction to the formation of feedback information for more efficient ABR traffic control. If backward node receive the longer delayed feedback information on the impending congestion, the switch can be already congested from the uncontrolled arriving traffic and the fluctuation of queue length can be inefficiently high in the continuing time intervals, The feedback control method proposed in this paper predicts the queue length in the switch using the slope of queue length prediction function and queue length changes in time-series, The predicted congestion information is backward to the node, NLMS and neural network are used as the predictive control functions, and they are compared from performance on the queue length prediction. Simulation results show the efficiency of the proposed method compared to the feedback control method without the prediction, Therefore, we conclude that the efficient congestion and stability of the queue length controls are possible using the prediction scheme that can resolve the problems caused from the longer delays of the feedback information.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.5
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• pp.469-479
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• 2014

N-RTK(Network based RTK) methods are able to improve the accuracy of GNSS positioning results through modelling of the distance-dependent error sources(i.e. primarily the ionospheric and tropospheric delays and orbit errors). In this study, the comparison of the TTFF(Time-To-Fix-First ambiguity), accuracy and discrepancies in horizontal/vertical components of N-RTK methods(VRS and FKP) with the static GNSS at 20 Unified Control Stations covering Incheon metropolitan city area during solar storms(Solar cycle 24 period) were performed. The results showed that the best method, compared with the statics GNSS survey, is the VRS, followed by the FKP, but vertical components of both VRS and FKP were approximately two times bigger than horizontal components. The reason for this is considered as the ionospheric scintillation because of irregularities in electron density, and the tropospheric scintillation because of fluctuations on the refractive index take the place. When the TTFF at each station for each technique used, VRS gave shorter initialization time than FKP. The possible reasons for this result might be the inherent differences in principles, errors in characteristics of different correction networks, interpolating errors of FKP parameters according to the non-linear variation of the dispersive and non-dispersive errors at rover when considering both domestic mobile communication infra and the standardized high-compact data format for N-RTK. Also, those test results revealed degradation of positing accuracy, long initialization time, and sudden re-initialization, but more failures to resolve ambiguity during space weather events caused by Sunspot activity and solar flares.

• Journal of Trauma and Injury
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• v.24 no.1
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• pp.25-30
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• 2011

Purpose: Major trauma patients should be transferred to a definitive care facility as early as possible because prompt management will prevent death. This study was designed to discover the obstacles leading to delayed transfers under the current emergency medical system in Korea and whether there are any negative outcomes associated with conducting procedures at primary care hospitals prior to transferring patients to higher levels of care. Methods: The medical records of major trauma patients with an Injury Severity Score above 15 within the past year were reviewed. Patients were divided three groups as follows: (A) came directly to our emergency center, (B) were transferred without CT or MRI scan at the primary care hospital and (C) transferred with CT or MRI scans. The transfer time of each group were compared and analyzed statistically. Additionally, the number and type of imaging performed at the primary care hospital were analyzed. Results: All qualified patients (n=276) were enrolled in this study: 121 patients in group A; 104 in group B; 51 in group C. There was a statistically significant difference in the transfer time between the three groups (p-value<0.001), and 79 (28.6%) were transferred to an emergency medical center within one hour. In group C, CT or MRI scans were performed an average of 1.86 times at the primary care hospital, and the median transfer time was 4 hours 5 minutes. Conclusion: Only 28.6% of the cases in the study arrived within the golden hour at a definitive care facility. Such delays are in part the result of prolonged times at the primary care hospital for radiologic examinations, such as CT or MRI scans. Major multiple trauma patients should be transferred to a definitive care facility directly or as soon as the primary survey and the resuscitation of Advanced Trauma Life Support guideline are completed at the primary care hospital.

• Magazine of the Korean Society of Agricultural Engineers
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• v.28 no.3
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• pp.79-88
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• 1986

Drought occurs most frequently and severely around transplanting season of the rice plants in Korea. Shortage of water due to drought for the paddy fields often delays transplanting, and less often the rice plants are subjected to water stress after delayed transplanting. The present study aimed at quantification of the rice crop loss due to delayed transplanting, different inten3ity of water stress, and the combined effect of delay in transplanting followed by water stress for better use of limited water for irrigation under drought. The rice variety Chucheong, a japonica, and Nampung, an indica x japonica, were grown, transplanted to 1/200 a plastic pots, and subjected to different timing of transplanting and degree of water stress under a rainfall autosersing, sliding clear plastic roof facility with completely randomized arrangement of 5 replications. The results obtained are summarized as follows: 1.Twelve days or 22 days delay in transplanting without water stress reduced rice yield by 25% and 43% in the japonica variety, and by 15% and 60% in the indica x japonica variety. 2.The 10 days or 20 days water stress developed without irrigation after drainage in the rice plants transplanted at proper time lowered the water potential at the paddy soil 10cm deep to -4 bar, and -12 bar and caused rice yield reduction by 14%, and 45% in the japonica variety and by 8%, and 50% in the indica X japonica variety. 3.The 12 days delay in transplanting and 10 days or 20 days water stress reduced rice yield by 39% and 59% in the japonica variety, and by 38% and 52% in the indica x japonica variety. The 22 days delay in transplanting plus 10 days water stress caused yield reduction by 76%, i.e. meaningless yield, in both varieties. 4.The intermittent irrigation just to wet the soil body for 10 days after 10 days water stress without irrigation increased rece yield by 12 to 16% compared to the rice plants water stessed without irrigation continuously for 20 days in both varieties respectively. 5.The above results suggest strongly 1) to transplant the rice plants at proper .time even with some water stress rather than delay for sufficient water from later rainfall, and 2) to distribute insufficient irrigation water to broader area of transplanted rice with limited irrigation for better use of limited irrigation water. A greater sensitivity of japonica variety to a moderate water stress than the indica X japonica variety during initial rooting and tillering stage was noticed. To cope with frequent drought in rice culture, firstly the lasting time of transplanting without yield reduction should be clarified by region and variety, and secondly a scheme of rational distribution of limited water should be developed by region with better knowledge on the varietal distribution of limited water should be developed by region with better knowledge on the varietal responses to varying intensity of water stress.

• The Journal of the Korea Contents Association
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• v.18 no.3
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• pp.611-625
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• 2018

With innovative advances in wireless communication technology, many researches for extending network lifetime in maximum by using energy harvesting have been actively performed on the area of network resource optimization, QoS-guaranteed transmission, energy-intelligent routing and etc. As known well, it is very hard to guarantee end-to-end network delay due to uncertainty of the amount of harvested energy in multi-hop RF(radio frequency) energy harvesting wireless networks. To minimize end-to-end delay in multi-hop RF energy harvesting networks, this paper proposes an energy efficient routing metric based on interference aware and protocol which takes account of various delays caused by co-channel interference, energy harvesting time and queuing in a relay node. The proposed method maximizes end-to-end throughput by performing avoidance of packet congestion causing load unbalance, reduction of waiting time due to exhaustion of energy and restraint of delay time from co-channel interference. Finally simulation results using ns-3 simulator show that the proposed method outperforms existing methods in respect of throughput, end-to-end delay and energy consumption.

• Journal of Trauma and Injury
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• v.25 no.4
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• pp.159-165
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• 2012

Purpose: For trauma patients, an early-transport and an organized process which are not delayed in hospital stage are necessary. Our hospital developed a procedure, the trauma Critical Pathway (CP), through which a traumatic patient has the priority over other patients, which makes the diagnostic and the therapeutic processes faster than they are for other patients. Methods: The records of patients to whom Trauma CP were applied from January 1, 2011 through April 15. 2012. were reviewed. We checked several time intervals from ER visiting to decision of admission-department, to performing first CT, to applying angio-embolization, to starting emergency operation and to discharging from ER. In addition, outcomes such as duration of ICU stay, hospital stay and mortality were checked and analyzed. Results: The trauma CP was applied to a total of 143 patients, of whom, 48 patients were excluded due to pre-hospital death, ER death, transferring to other hospital and not severe injury. Thus 95 patients (male 64, 67.3%) were enrolled in this study. Fifty-nine patients(62.1%) were injured by the traffic accident. The mortality rate was 10.5% and the mean Revised Trauma Score (RTS) of the patients was $6.4{\pm}2.0$. After visiting ER, decision making for admission was completed, on average, in 3 hours 10 seconds. The mean time intervals for the first CT, angio-embolization, surgery and discharge were 1 hour 20 minutes, 5 hours 16 minutes, 7 hours 26 minutes and 6 hours 13 minutes, respectively. Conclusion: The trauma CP did not show the improvement of time interval outcome, as well as mortality rate. However, this test did show that the trauma CP might be able to reduce delays in procedures for managing trauma patients at the university-based hospitals. To find out the benefit of CP protocol, a large scaled data is required.

• Science of Emotion and Sensibility
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• v.8 no.4
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• pp.423-433
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• 2005

The computer hardware development has provided many chances of emergence between art and technology. In many cases today's interactive artworks cannot be completed without audience's participation. The interactive production process with technical supplementation can be celled feedback. Mr. Nam Jun Paik showed 'Participant TV' that interacts with audience's response in real time. It means artwork changes with the constantly changing value from the data set from human visual perception. Dan Graham showed another feedback related work, which delays 5second playback in mirror that implies consequence of time. Today's media art has to sublimate coincidence, time ant audience into philosophical artwork through consonance that comes with video and sound as we can see from Bill Viola. Stelarc produced artworks. That use input data that is weak signals from brain, muscles. Through a terminal display with player, body expanded meaning of media. Jeffrey Shaw's 'Legible City' provided a fabrication of the reality with the interaction of bicycle's pedal speed and steering direction that is controlled by 4river. RE:MARK used microphone as input device as Edmond Couchot's 'Je same a la vent' and Nam Jun Paik's 'Participant TV' did. There is no communication without feedback between human being. The reality makes audience involved into artworks. That is the reason why feedback has to be natural. Through the feedback process, the originality of the idea is altered by audience. The feedback is not just part of flesh of artwork rather skeleton of it. Technological showoff cannot be art itself The perfection of technological application plan helps feedback that interacts with audience naturally in order that audience hoes not feel the feedback as artificial plan. Interactive media art has to be evolved into new media form with new integration feedback technology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6C
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• pp.495-505
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• 2010

In this paper, the effect of Near-Far Problem (NFP) among distributed nodes in OFDMA-based Wireless Mesh Networks (WMNs) is analyzed by investigating statistical characteristics of Time Difference of Arrival (TDoA) and Desired-to-Undesired power Ratio (DUR). In order to overcome the effects of Inter-Symbol Interference (ISI), Inter-Carrier Interference (ICI), and Inter Link Interference (ILI), caused by TDoA in WMNs, we derive effective SINR for each subcarrier, and then, propose the optimal starting point of FFT window which can minimize BER for each subcarrier. In addition, we propose a subcarrier-based Zero Forcing - 2 Dimensional Ordered Successive Interference Cancellation (ZF-2DOSIC) technique for signal detection in WMNs with TDoA. It is verified by simulation that the effective SINR and uncoded BER performances of the proposed signal detection technique for OFDMA-based WMNs are significantly improved, compared with those of conventional technique.