• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.2
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• pp.1-14
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• 1998

The purpose of this study is to find out how the urban landscape of Korea, especially Seoul, changed during the last half century since 1945. The modernization of Korea, which had begun in 1960's after the chaotic period caused by Korean War, influenced the rapid growth of cities and the radical changes of its structures. But the Western-minded planning theories based on rationalism and positivism was directly applied in developing our traditional cities and consequently the modern urban landscape including urban pattern, architectural style, and commercial and residential landscape revealed disharmony, discrepancy and inconsistency in skylines, streetscape and so on. The findings are summarized as follows. 1. Because the urban structure and pattern changed in undesirable manner in terms of land use and traffic circulation, cities as a whole resulted in exclusive and heterogeneous landscape, and citizens lost their identity and felt alienated. 2. Because the architectural forms of important and monumental buildings which influenced the character of streetscape were not so successful in inventing contemporary Korean Style in true sense, we still have difficulty in creating the urban landscape of originality and legibility. 3. Because from the beginning of this era almost all highrise buildings were designed by modernism-oriented western architects, the commercial landscape of central cities did not evoke a sense of place, and after the introduction of postmodernism this tendency is ore striking even in everyday ordinary streetscape. 4. The newly formed residential landscape which was mainly composed of highly dense and highrise apartment, not only evolved very overwhelming and ugly visual impact but also exposed many social problems in living condition, neighboring and face-to-face contact. In conclusion, in ordr to define the 'Koreanness' of our urban landscape, we have to struggle to combine traditional architectural heritage and native townscape with Western shape, thought and theory, no matter how difficult it may be.

• Journal of Environmental Science International
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• v.16 no.10
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• pp.1157-1167
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• 2007

In an effort to interpret the characteristics of fine particle concentrations in Busan, time variations of hourly monitored concentrations $PM_{10}$ (Particulate Matter with aerodynamic Diameter ${\le}10\;{\mu}m$) in Busan are analyzed for the period from 2000 to 2005. The characteristics of aerosol second generation formation process is also interpreted qualitatively, by using the statistical analysis of the meteorological variables including temperature, wind speed, and relative humidity. The result shows some significant annual, seasonal, weekly and diurnal variations of $PM_{10}$ concentrations. In particular, seasonal(i.e., spring) variations are governed by frequency of yellow sand events even for the non-yellow sand cases where yellow-sand days are eliminated in our analysis. However, in seasonal variation, summer season predominate lower $PM_{10}$ concentrations due to the frequent precipitation, and weekly and diurnal variations are both found to be reflecting the emission rate from traffic amount. Correlation coefficients between $PM_{10}$ concentration and meterological variables for non-yellow sand days show overall negative correlation with visibility, wind speed, cloud amounts, and relative humidity. However for non-precipitation days, during non-yellow sand period positive correlation are found clearly with relative humidity, suggesting the importance of secondary aerosol formation in Busan that can be achieved by both homogeneous aerosol formation and heterogeneous transformations resulting from hygroscopic aerosol characteristics.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.364-374
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• 2016

With vast amounts of spectrum available in the millimeter wave (mmWave) band, small cells at mmWave frequencies densely deployed underlying the conventional homogeneous macrocell network have gained considerable interest from academia, industry, and standards bodies. Due to high propagation loss at higher frequencies, mmWave communications are inherently directional, and concurrent transmissions (spatial reuse) under low inter-link interference can be enabled to significantly improve network capacity. On the other hand, mmWave links are easily blocked by obstacles such as human body and furniture. In this paper, we develop a multi-hop relaying transmission (MHRT) scheme to steer blocked flows around obstacles by establishing multi-hop relay paths. In MHRT, a relay path selection algorithm is proposed to establish relay paths for blocked flows for better use of concurrent transmissions. After relay path selection, we use a multi-hop transmission scheduling algorithm to compute near-optimal schedules by fully exploiting the spatial reuse. Through extensive simulations under various traffic patterns and channel conditions, we demonstrate MHRT achieves superior performance in terms of network throughput and connection robustness compared with other existing protocols, especially under serious blockage conditions. The performance ofMHRT with different hop limitations is also simulated and analyzed for a better choice of the maximum hop number in practice.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.3
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• pp.205-218
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• 2012

Mobility management of the mobile nodes and provision of seamless handover is crucial to an efficient support for the global roaming of the mobile nodes in next-generation wireless networks. Mobile IPv6 and mobility management in extended IP layer, which highly depend on traffic characteristics and user mobility models, were proposed by the IETF. Therefore, to evaluate the in-depth performance about these factors is important. Generally, the performance of IPv6-based mobility management protocol is evaluated through simulation. This paper shows the correlation between network parameters and performance metrics through numerical results, which is investigated how influence handoff latency and packet loss. And this paper uses mathematical analysis of the system parameters, such as the subnet residence time, the packet arrival rate and delay in wireless connection through the analytical framework which evaluate the performance of IPv6-based mobility management protocol.

• Journal of Satellite, Information and Communications
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• v.12 no.2
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• pp.94-98
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• 2017

In this paper, we design a transmission / receiver structure to provide additional data service based on Mobile MMT in hybrid network environment. Mobile MMT is an extended standard of MMT, the next generation multimedia transmission protocol. MMT defines technologies for efficiently transmitting multimedia and supporting various types of data transmission and bidirectional services over heterogeneous networks based on IP. The Mobile MMT further defines the extended functions to provide functions specific to the mobile network based on the existing MMT technology. In this paper, we design and propose a additional data service scenario and additional data transmission / receiver structure that can receive additional data related to contents delivered through broadcasting network and additional data such as traffic, weather, traveler information related to user information.

• Journal of Korean Society of Transportation
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• v.23 no.1
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• pp.83-92
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• 2005

This study if the first trial toward realizing a new methodology for vehicle re-identification based on heterogeneous sensor systems. A major interest of the author is how to effectively utilize information obtained from different sensors to derive accurate and reliable section travel times. The 'blade' sensor that is a newly developed sensor for capturing vehicle wheel information and the existing square loop sensor are employed to extract the inputs of the proposed vehicle re-identification algorithm. The fundamental idea of the algorithm developed in this study, which is so called 'anonumous vehicle re-identification,' it to match vehicle features obtained from both sensors. The results of the algorithm evaluation reveal that the proposed methodology could be successfully implemented in the field. The proposed methodology would be an invaluable tool for operating agencies in support of traffic monitoring systems and traveler information systems.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.7
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• pp.257-262
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• 2021

Accidents caused by black ice occur frequently every winter, and the fatality rate is very high compared to other traffic accidents. Therefore, a systematic method is needed to predict the black ice formation before accidents. In this paper, we proposed a black ice prediction model based on heterogenous and multi-type data. To this end, 12,574,630 cases of 46 types of land, infrastructure, transport public data and meteorological public data were collected. Subsequently, the data cleansing process including missing value detection and normalization was followed by the establishment of approximately 600,000 refined datasets. We analyzed the correlation of 42 factors collected to predict the occurrence of black ice by selecting only 21 factors that have a valid effect on black ice prediction. The prediction model developed through this will eventually be used to derive the route-specific black ice risk index, which will be utilized as a preliminary study for black ice warning alart services.

• The KIPS Transactions:PartA
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• v.15A no.1
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• pp.53-60
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• 2008

Streaming media has contributed to a significant amount of today's Internet Traffic. Like traditional web objects, rich media objects can benefit from proxy caching, but caching streaming media is more of challenging than caching simple web objects, because the streaming media have features such as huge size and high bandwidth. And to support various bandwidth requirements for the heterogeneous ubiquitous devices, a transcoding proxy is usually necessary to provide not only adapting multimedia streams to the client by transcoding, but also caching them for later use. The traditional proxy considers only a single version of the objects, whether they are to be cached or not. However the transcoding proxy has to evaluate the aggregate effect from caching multiple versions of the same object to determine an optimal set of cache objects. And recent researches about multimedia caching frequently store initial parts of videos on the proxy to reduce playback latency and archive better performance. Also lots of researches manage the contents with segments for efficient storage management. In this paper, we define the 9-events of transcoding proxy using 4-atomic events. According to these events, the transcoding proxy can define the next actions. Then, we also propose the segment-based caching policy for the transcoding proxy system. The performance results show that the proposing policy have a low delayed start time, high byte-hit ratio and less transcoding data.

• The KIPS Transactions:PartA
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• v.16A no.4
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• pp.263-272
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• 2009

For implementing the ubiquitous computing environments with smart home infrastructures, various research on the home network have been performed by several research institutes and companies. Due to the various home network middleware that are developed recently, the standardization of the home network middleware is being delayed and it calls for the middleware bridge which solves the interoperability problem among the heterogeneous middlewares. Now the research on the scheme for interoperability and the development of the various bridges are in progress, such as one-to-one bridge supporting interoperability between two middlewares and one-to-many bridge supporting interoperability among the multi-middlewares. However, existing systems and schemes does not consider the dynamic extensibility and performance that is particularly needed in the smart home environments. The middleware bridge should provide bridge extensibility with zero-configuration for non-expert users. It should also provide the load balancing scheme for efficient and proper traffic distribution. In this paper, we propose a Multi-Middleware Bridge(MMB) for dynamic extensibility and load balancing in home network environments. MMB provides bridge scalability and load balancing through the distributed system structure. We also verify the features such as interoperability, bridge extensibility, and the performance of the load balancing algorithm.

• Journal of Internet Computing and Services
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• v.24 no.1
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• pp.1-7
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• 2023

Recently, the technology of device-to-device(D2D) communication has been receiving big attention to improve the system performance since the amount of high quality/large capacity data traffic from smart phones and various devices of Internet of Things increase rapidly in 5G/6G based next generation cellular networks. However, even though the system performance of macro cells increase by reusing the frequency, the performance of macro user equipments(MUEs) decrease because of the strong interference from D2D user equipments(DUEs). Therefore, this paper proposes a dynamic channel management(DCM) scheme for DUEs to guarantee the performance of MUEs as the number of DUEs increases in next generation downlink cellular networks. In the proposed D2D DCM scheme, macro base stations dynamically assign subchannels to DUEs based on the interference information and signal to interference and noise ratio(SINR) of MUEs. Simulation results show that the proposed D2D DCM scheme outperforms other schemes in terms of the mean MUE capacity as the threshold of the SINR of MUEs incareases.