• Journal of Intelligence and Information Systems
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• v.27 no.1
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• pp.191-207
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• 2021

Up to this day, mobile communications have evolved rapidly over the decades, mainly focusing on speed-up to meet the growing data demands of 2G to 5G. And with the start of the 5G era, efforts are being made to provide such various services to customers, as IoT, V2X, robots, artificial intelligence, augmented virtual reality, and smart cities, which are expected to change the environment of our lives and industries as a whole. In a bid to provide those services, on top of high speed data, reduced latency and reliability are critical for real-time services. Thus, 5G has paved the way for service delivery through maximum speed of 20Gbps, a delay of 1ms, and a connecting device of 106/㎢ In particular, in intelligent traffic control systems and services using various vehicle-based Vehicle to X (V2X), such as traffic control, in addition to high-speed data speed, reduction of delay and reliability for real-time services are very important. 5G communication uses high frequencies of 3.5Ghz and 28Ghz. These high-frequency waves can go with high-speed thanks to their straightness while their short wavelength and small diffraction angle limit their reach to distance and prevent them from penetrating walls, causing restrictions on their use indoors. Therefore, under existing networks it's difficult to overcome these constraints. The underlying centralized SDN also has a limited capability in offering delay-sensitive services because communication with many nodes creates overload in its processing. Basically, SDN, which means a structure that separates signals from the control plane from packets in the data plane, requires control of the delay-related tree structure available in the event of an emergency during autonomous driving. In these scenarios, the network architecture that handles in-vehicle information is a major variable of delay. Since SDNs in general centralized structures are difficult to meet the desired delay level, studies on the optimal size of SDNs for information processing should be conducted. Thus, SDNs need to be separated on a certain scale and construct a new type of network, which can efficiently respond to dynamically changing traffic and provide high-quality, flexible services. Moreover, the structure of these networks is closely related to ultra-low latency, high confidence, and hyper-connectivity and should be based on a new form of split SDN rather than an existing centralized SDN structure, even in the case of the worst condition. And in these SDN structural networks, where automobiles pass through small 5G cells very quickly, the information change cycle, round trip delay (RTD), and the data processing time of SDN are highly correlated with the delay. Of these, RDT is not a significant factor because it has sufficient speed and less than 1 ms of delay, but the information change cycle and data processing time of SDN are factors that greatly affect the delay. Especially, in an emergency of self-driving environment linked to an ITS(Intelligent Traffic System) that requires low latency and high reliability, information should be transmitted and processed very quickly. That is a case in point where delay plays a very sensitive role. In this paper, we study the SDN architecture in emergencies during autonomous driving and conduct analysis through simulation of the correlation with the cell layer in which the vehicle should request relevant information according to the information flow. For simulation: As the Data Rate of 5G is high enough, we can assume the information for neighbor vehicle support to the car without errors. Furthermore, we assumed 5G small cells within 50 ~ 250 m in cell radius, and the maximum speed of the vehicle was considered as a 30km ~ 200 km/hour in order to examine the network architecture to minimize the delay.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.9
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• pp.73-80
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• 2004

In this paper, we present the cell resequencing buffer to solve the cell sequence integrity problem of the Cyclic banyan network that is a high-performance fault-tolerant cell switch. By offering multiple paths between input ports and output ports, using the deflection self-routing, the Cyclic banyan switch offer high reliability, and it also solves congestion problem for the internal links of the switch. By the way, these multiple paths can be different lengths for each other. Therefore, the cells departing from an identical source port and arriving at an identical destination port can reach to the output port as the order that is different from the order arriving at input port. The proposed cell resequencing buffer is a hardware sliding window mechanism. to solve such cell sequence integrity problem. To calculate the size of sliding window that cause the prime cost of the presented device, we analyzed the distribution of the cell delay through the simulation analyses under traffic load that have a nonuniform address distribution that express tile Property of traffic of the Internet. Through these analyses, we found out that we can make a cell resequencing buffer by which the cell sequence integrity is to be secured, by using a, few of ordinary memory and control logic. The cell resequencing buffer presented in this paper can be used for other multiple paths switching networks.

• Journal of Korean Society of Transportation
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• v.26 no.6
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• pp.39-47
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• 2008

With dramatic development of IT technology and start of DMB service, installing the DMB equipment in a vehicle for watching TV programs and literal or pictorial traffic information are increasing. Watching the DMB during driving the vehicle could cause visual and cognitive distraction to drivers as much as eating food, operating radio and using mobile phone. However, there is not much empirical research for this topic and no research examined the effect of watching the DMB on driving behaviors in Korea. So, the present study examined the effect of watching the DMB on the driving behaviors with car simulator experiment. Within subject design was used in the study. That is, all subjects drove the vehicle both in the watching DMB condition and the non-watching DMB condition. The results indicated that subjects in the watching DMB condition took longer time to arrive at the destination and operated accelerator and brake pedal rapidly than subjects in the non-watching DMB condition. That is, their overall driving stability was lower than non-watching subjects'. Additionally, we examined the difference among the DMB control conditions (i.e., keypad condition, touch-pad condition and remote controller condition) in the driving behaviors. Finally, we discussed the limitations and the implications of the present study.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.1
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• pp.38-53
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• 2007

In a seminal judgment of November 2002 (Case C-476/98) relating to the compatibility with Community laws of the 'nationality clause' in the 1996 amending protocol to the 1955 U.S.-German Air Services Agreement, the European Court of Justice(ECJ) decided that the provision constituted a measure of an intrinsically discriminatory nature and was thus contrary to the principle of national treatment established under Art. 52 of the EC Treaty. The Court, rejecting bluntly the German government' submissions relying on public policy grounds(Art. 56, EC Treaty), seemed content to declare and rule that the protocol provision requiring a contracting state party to ensure substantial ownership and effective control by its nationals of its designated airlines had violated the requirement of national treatment reserved for other Community Members under the salient Treaty provision. The German counterclaims against the Commission, although tantalizing not only from the perusal of the judgment but from the perspective of international air law, were nonetheless invariably correct and to the point. For such a clause has been justified to defend the 'fundamental interests of society from a serious threat' that may result from granting operating licenses or necessary technical authorizations to an airline company of a third country. Indeed, the nationality clause has been inserted in most of the liberal bilaterals to allow the parties to enforce their own national laws and regulations governing aviation safety and security. Such a clause is not targeted as a device for discriminating against the nationals of any third State. It simply acts as the minimum legal safeguards against aviation risk empowering a party to take legal control of the designated airlines. Unfortunately, the German call for the review of such a foremost objective and rationale underlying the nationality clause landed on the deaf ears of the Court which appeared quite happy not to take stock of the potential implications and consequences in its absence and of the legality under international law of the 'national treatment' requirement of Community laws. Again, while US law limits foreign shareholders to 24.9% of its airlines, the European Community limits non-EC ownership to 49%, precluding any ownership and effective control by foreign nationals of EC airlines, let alone any foreign takeover and merger. Given this, it appears inconsistent and unreasonable for the EC to demand, $vis-{\grave{a}}-vis$ a non-EC third State, national treatment for all of its Member States. The ECJ's decision was also wrongly premised on the precedence of Community laws over international law, and in particular, international air law. It simply is another form of asserting and enforcing de facto extraterritorial application of Community laws to a non-EC third country. Again, the ruling runs counter to an established rule of international law that a treaty does not, as a matter of principle, create either obligations or rights for a third State. Aside from the legal problems, the 'national treatment' may not be economically justified either, in light of the free-rider problem and resulting externalities or inefficiency. On the strength of international law and economics, therefore, airlines of Community Members other than the designated German and U.S. air carriers are neither eligible for traffic rights, nor entitled to operate between or 'free-ride' on the U.S. and German points. All in all and in all fairness, the European Court's ruling was nothing short of an outright condemnation of established rules and principles of international law and international air law. Nor is the national treatment requirement justified by the economic logic of deregulation or liberalization of aviation markets. Nor has the requirement much to do with fair competition and increased efficiency.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.71-71
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• 2018

Sea pollution accidents have been occurred due to the increase of marine ship traffic. Oil spill from the hull hole induced by tanker collision results in the huge sea pollution. Proper and prompt reaction on such oil spill disaster is needed to minimize the damage. Thru-hull emergency wood plug is typically used to manually close small holes, while it is required to develop some mechanical devices for closing large holes in the hull due to huge fluid pressure. Accurate estimation of oil discharge and velocity from such holes are important to develop proper device to control hull hole damage. High resolution CFD modeling investigation on the configurations of hull hole of 7.5 m initial depth and 30 cm diameter, which was observed in the oil spill accident of the Hebei Sprit off the west coast of Korea in 2007, has been carried out to compute the oil spill velocity distribution in terms of flow depth. Friction loss due to the viscous flow and the discharge coefficient of crude oil with specific gravity SG = 0.85 and viscosity of $4-12cP(mPa{\cdot}s)$ at the temperature of $20^{\circ}C-100^{\circ}C$ are presented in terms of Reynolds number based on the results of high-resolution CFD modeling.

• Journal of Trauma and Injury
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• v.36 no.4
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• pp.343-353
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• 2023

Purpose: The COVID-19 pandemic led to significant changes in the lifestyle patterns of children and affected the patterns of pediatric injuries. This study analyzed the changing patterns of pediatric injury overall and by age groups, based on the datasets before and during the COVID-19 pandemic. Methods: This study is based on the data of patients who presented with injuries at 23 hospital emergency departments participating in the Emergency Department-based Injury In-depth Surveillance (EDIIS) conducted by the Korea Disease Control and Prevention Agency. The surveillance data was categorized by injury mechanism, location, activity, and severity. We analyzed the injury patterns of pediatric patients aged 0 to 15 years. Subgroup analysis was conducted by age group in children aged 7 to 15 years, 1 to 6 years, and <1 year. Results: When comparing the COVID-19 pandemic period to the pre-COVID-19 period, the total number of pediatric patients with injuries decreased by 38.7%, while the proportions of in-home injuries (57.9% vs. 67.9%), and minor injuries (38.9% vs. 39.7%) increased. In the 7 to 15 years group, bicycle riding injuries (50.9% vs. 65.6%) and personal mobility device injuries (2.4% vs. 4.6%) increased. The 1 to 6 years group also showed an increase in bicycle accident injuries (15.8% vs. 22.4%). In the <1 year group, injuries from falls increased (44.5% vs. 49.9%). Self-harm injuries in the 7 to 15 years group also increased (1.6% vs. 2.8%). Conclusions: During the COVID-19 pandemic period, the overall number of pediatric injuries decreased, while injuries occurring at home and during indoor activities increased. Traffic accidents involving bicycles and personal mobility devices and self-harm injuries increased in the 7 to 15 years group. In the <1 year group, the incidence of falls increased. Medical and societal preparedness is needed so that we might anticipate these changes in the patterns of pediatric injuries during future infectious disease pandemics.

• Journal of Intelligence and Information Systems
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• v.26 no.2
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• pp.131-145
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• 2020

In line with the trend of industrial innovation, IoT technology utilized in a variety of fields is emerging as a key element in creation of new business models and the provision of user-friendly services through the combination of big data. The accumulated data from devices with the Internet-of-Things (IoT) is being used in many ways to build a convenience-based smart system as it can provide customized intelligent systems through user environment and pattern analysis. Recently, it has been applied to innovation in the public domain and has been using it for smart city and smart transportation, such as solving traffic and crime problems using CCTV. In particular, it is necessary to comprehensively consider the easiness of securing real-time service data and the stability of security when planning underground services or establishing movement amount control information system to enhance citizens' or commuters' convenience in circumstances with the congestion of public transportation such as subways, urban railways, etc. However, previous studies that utilize image data have limitations in reducing the performance of object detection under private issue and abnormal conditions. The IoT device-based sensor data used in this study is free from private issue because it does not require identification for individuals, and can be effectively utilized to build intelligent public services for unspecified people. Especially, sensor data stored by the IoT device need not be identified to an individual, and can be effectively utilized for constructing intelligent public services for many and unspecified people as data free form private issue. We utilize the IoT-based infrared sensor devices for an intelligent pedestrian tracking system in metro service which many people use on a daily basis and temperature data measured by sensors are therein transmitted in real time. The experimental environment for collecting data detected in real time from sensors was established for the equally-spaced midpoints of 4×4 upper parts in the ceiling of subway entrances where the actual movement amount of passengers is high, and it measured the temperature change for objects entering and leaving the detection spots. The measured data have gone through a preprocessing in which the reference values for 16 different areas are set and the difference values between the temperatures in 16 distinct areas and their reference values per unit of time are calculated. This corresponds to the methodology that maximizes movement within the detection area. In addition, the size of the data was increased by 10 times in order to more sensitively reflect the difference in temperature by area. For example, if the temperature data collected from the sensor at a given time were 28.5℃, the data analysis was conducted by changing the value to 285. As above, the data collected from sensors have the characteristics of time series data and image data with 4×4 resolution. Reflecting the characteristics of the measured, preprocessed data, we finally propose a hybrid algorithm that combines CNN in superior performance for image classification and LSTM, especially suitable for analyzing time series data, as referred to CNN-LSTM (Convolutional Neural Network-Long Short Term Memory). In the study, the CNN-LSTM algorithm is used to predict the number of passing persons in one of 4×4 detection areas. We verified the validation of the proposed model by taking performance comparison with other artificial intelligence algorithms such as Multi-Layer Perceptron (MLP), Long Short Term Memory (LSTM) and RNN-LSTM (Recurrent Neural Network-Long Short Term Memory). As a result of the experiment, proposed CNN-LSTM hybrid model compared to MLP, LSTM and RNN-LSTM has the best predictive performance. By utilizing the proposed devices and models, it is expected various metro services will be provided with no illegal issue about the personal information such as real-time monitoring of public transport facilities and emergency situation response services on the basis of congestion. However, the data have been collected by selecting one side of the entrances as the subject of analysis, and the data collected for a short period of time have been applied to the prediction. There exists the limitation that the verification of application in other environments needs to be carried out. In the future, it is expected that more reliability will be provided for the proposed model if experimental data is sufficiently collected in various environments or if learning data is further configured by measuring data in other sensors.