• Journal of Environmental Health Sciences
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• v.50 no.2
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• pp.81-82
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• 2024

Urban air mobility (UAM) is emerging as an innovative transportation solution for cities. However, the potential noise impact on urban life must be carefully examined. Continuous exposure to UAM noise, with its unique frequency characteristics and temporal variability, may adversely affect citizens' health by causing sleep disorders, cardiovascular disease, and cognitive impairmenet, particularly in children. NASA has formed a UAM Noise Working Group to study this issue comprehensively. In Korea, the Seoul Metropolitan Government's UAM demonstration project is expected to accelerate related research and development. Scientific analysis, including noise measurement, prediction modeling, and health impact assessment, must be prioritized. Measures to minimize noise should be established based on this evidence, such as optimizing flight modes, developing noise reduction technologies, and establishing new noise management standards. Transparency and social consensus are crucial throughout this process. Expert review and open communication with civil society are necessary to address related concerns. Sharing demonstration project results and providing opportunities to experience UAM noise through digital twin simulations can help address public concerns and build social consensus. Proactively and scientifically tackling noise issues is essential for the sustainable development and successful integration of UAM into daily life.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.2
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• pp.135-144
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• 2003

Traffic performance in a microcellular system is much more affected by cell dwell time and channel holding time in each cell. Cell dwell time of a call is characterized by its mobility pattern, i.e., stochastic changes of moving speed and direction. Cell dwell time provides important information for other analyses on traffic performance such as channel holding time, handover rate, and the average number of handovers per call. In the next generation mobile communication system, the cell size is expected to be much smaller than that of current one to accommodate the increase of user demand and to achieve high bandwidth utilization. As the cell size gets small, traffic performance is much more affected by variable mobility of users, especially by that of pedestrians. In previous work, analytical models are based on simple probability models. They provide sufficient accuracy in a simple second-generation cellular system. However, the role of them is becoming invalid in a picocellular environment where there are rapid change of network traffic conditions and highly random mobility of pedestrians. Unlike in previous work, we propose an improved probability model evolved from so-called Random walk model in order to mathematically formulate variable mobility of pedestrians and analyze the traffic performance. With our model, we can figure out variable characteristics of pedestrian mobility with stochastic correlation. The above-mentioned traffic performance measures are analyzed using our model.

• Korean journal of communication and information
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• v.18
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• pp.37-61
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• 2002

The mobile phone is a medium of mobility in the sense that it makes possible anytime, anywhere communications. It is also a medium of privatism as it opens for the users an exclusive communication space that marks private territoriality. These two characteristics associated with the mobile phone are usually interpreted as part of its technical properties and convenience it provides to the users. But mobility is offered not just for the sake of mobility, nor privatism is for the sake of privatism. There are certain social and political economic conditions that enhance and even force us to be mobile and private. The mobile phone symbolizes this kind of world order in which mobility and privatism condition our social life-world.

• Journal of Sensor Science and Technology
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• v.33 no.2
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• pp.93-97
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• 2024

With the development of promising future mobility and urban air mobility (UAM) technologies, the demand for LIDAR sensors has increased. The SWIR photodetector is a sensor that detects lasers for the 3D mapping of lidar sensor and is the most important technology of LIDAR sensor. An SWIR photodetector based on QDs in an eye-safe wavelength band of over 1400 nm has been reported. QDs-based SWIR photodetectors can be synthesized and processed through a solution process and have the advantages of low cost and simple processing. However, the organic ligands of QDs have insulating properties that limit their ability to improve the sensitivity and stability of photodetectors. Therefore, the technology to replace organic ligands with inorganic ligands must be developed. In this study, the organic ligand of the synthesized PbS QDs was replaced with a MAPI inorganic ligand, and an SWIR photodetector was fabricated. The analysis of the characteristics of the manufactured photodetector confirmed that the photodetector based on MAPI-capped PbS QDs exhibited up to 26.5% higher responsivity than that based on organic ligand PbS QDs.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.4
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• pp.107-118
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• 2022

As connected and automated driving(CAD) technology is entering its commercialization stage, service platforms providing CAD-based mobility services have increased these days. However, CAD-baded mobility services with these platforms need more consideration for the demand for mobility services when determining target areas for CAD-based mobility services because current CAB-based mobility design focus on driving performance and driving stability. For a more efficient design of CAD-based mobility services, we analyzed the applicability for the introduction of CAD-based mobility services in terms of driving difficulty of CAD and demand patterns of current non-CAD based-mobility services, e.g., taxi, demand-responsive transit(DRT), and special transportation systems(STS). In addition, for the spatial analysis of the applicability of the CAD-based mobility service, we propose the Index for Autonomous Driving Applicability (IADA) and analyze the characteristics of the spatial distribution of IADA from the network perspective. The analysis results show that the applicability of CAD-based mobility services depends more on the demand patterns than the driving difficulty of CAV. In particular, the results show that the concentration pattern of demand in a specific road link is more important than the size of demand. As a result, STS service shows higher applicability compared to other mobility services, even though the size of demand for this mobility service is relatively small.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.972-973
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• 2007

Relationships between field effect mobility and grain size on pentacene thin-film transistors with $polyimide/SiO_2$ gate dielectrics have been studied. 6 kinds of polyimide were used as surface treatment gate dielectric layer. Grain size of the pentacene thin film were between 5 and $30\;{\mu}m$ and depended on the polyimide. The field effect mobility were also depended on the polyimide and the those values were from 0.027 to $0.69\;cm^2/(Vs)$. The field effect mobility tends to increase with increasing the grain size. Precursor type polyimide containing polyamic acid show better mobility of $0.69\;cm^2/(Vs)$ than soluble type polyimide. Bias stress characteristics in air are discussed in the basis of the grain size.

• Korean Institute of Interior Design Journal
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• v.20 no.2
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• pp.110-119
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• 2011

The purpose of this study is to analyze the development and characteristics of Dymaxion housing by R. B. Fuller, who is generally known as a structure engineering, architect and his influences. A document research method was used to analyze and classified of his dymaxion housing projects focused on the late of 1920's. Through this study, the following conclusions have been reached; 1) In order to obtain the productivity and efficiency drawing from the industrialized housing in the early of 1900s, the planning concepts of 'Dymaxion', 'Ehemeralization' and 'Autonomy' were proposed. 2) The planning characteristics of Dymaxion housing projects are classified as three aspects. The first is 'formative aspects' which was focused on the round-shape, transparency and lightweight material such as aluminium for movable and flexible dwelling. The second is 'functional aspects', focused on the mass-production, mobility, flexibility, high-tech and systemizing mechanical equipments for efficiency of household affairs. The third is 'environmental aspects', focused on the energy-saving and environmental control for sustainable dwelling. Dymaxion housing projects of Fuller, an aggregation of high-tech mechanical equipments, had a great impact on the development the concept of mobility and influenced radical and utopian architectural groups' ideas of 1960's. Especially, considering today's high cost of energy and the limited natural resources, Fuller's Dymaxion theory must be re-evaluated.

• The Transactions of the Korea Information Processing Society
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• v.7 no.4
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• pp.1217-1226
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• 2000

Traditionally, Mobile Teletraffic model consists of two sub-models, i.e. the network traffic model and the traffic source model. In this paper, we present the traffic source model by developing MobCall (Mobile Call Simulator) which analyses various mobile wireless environments based on regional characteristics that the base stations are located. User mobility is presented by regional average vehicle speeds and the transportation share rate. Moreover, the user mobility on subway, which is increasing in urban area, is considered in MobCall. And also, user's movements on highway are considered in MobCall. The object-oriented simulation platform, C++SIM, is used to implement MobCall. Using MobCall, the accumulated number of calls in residential and commercial regions, the handoff rate with respect to traffic sources of Seoul, the handoff rate on highway, and the handoff rate according to the call duration are presented. MobCall enables the simulation of dynamic handoff buffering and functional entity control of one base station according to the changes in user's calling pattern at the design phase. Also, when a new town is under construction by a detailed plan, MobCall is used to design the mobile network with regional characteristics and user mobility considered.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.7-8
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• 2007

We investigated the characteristics of UTB-SOI pMOSFETs with SOI thickness ($T_{SOI}$) ranging from 10 nm to 1 nm and evaluated the dependence of electrical characteristics on the silicon surface orientation. As a result, it is found that the subthreshold characteristics of (100)-surface UTB-SOI pMOSFETs were superior to (110)-surface. However, the hole mobility of (110)-surface were larger than that of (100)-surface. The enhancement of effective hole mobility at the effective field of 0.1 MV/ccm was observed from 3-nm to 5-nm SOI thickness range.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.393-396
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• 1988

In discharge excited excimer laser, it is hard to say that the analysis of laser operation was well explained until now. But this can be improved by analysis the nonlinear discharge characteristics in the cavity. The nonlinear characteristics can be analysed by solving the nonlinear resistance which depends on electron mobility and number density. We can calculate the electron mobility and number density each other using Boltzmann equation and Kinetics equation. So we calculated the nonlinear resistance and analysed nonlinear discharge characteristics.