• Journal of the Korean Regional Science Association
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• v.36 no.3
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• pp.3-16
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• 2020

The causes and effects of intra-urban spatial inequality have received much scholarly attention. However, the effects of urban spatial inequality on resident perceptions and the mechanisms through which it is sustained and reproduced remain mostly unknown. This study aimed to investigate whether regional deprivation, the relative socioeconomic standing of a region, affects the residents' perceptions of upward social mobility. By employing the ordinal logistic multilevel model to analyze nested data collected from Seoul, South Korea, this study found that the regional deprivation has a significant negative effect on residents' perception of upward social mobility. The results of this study suggest that one way in which spatial inequality is sustained and reproduced is by the effects of regional deprivation, having negative impacts on the aspirations and socioeconomic activities of residents. This study is expected to provide meaningful implications for planning and policy aimed to combat spatial inequality.

• Journal of Advanced Navigation Technology
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• v.26 no.3
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• pp.125-135
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• 2022

UAM is emerging as the biggest issue in the aviation industry and which is attracting a lot of attention not only domestically but also internationally. In Korea, active research is being conducted centered on the government and industry-university research institutes, such as the establishment of a future K-UAM concept of operation. Therefore, in this study applies the SORA (Specific Operation Risk Assessment) model established by the European JARUS (Joint Authorities for Rulemaking on Unmanned Systems) to apply the K-UAM operation environment and specific corridor for the purpose of cargo transportation that will be operated in the future that the government is promoting. We intend to suggest policy and technical measures for risk mitigation in the initial operating environment by evaluating the level of risk and analyzing the results.

• Journal of Digital Convergence
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• v.19 no.11
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• pp.301-313
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• 2021

The automotive industry is facing a paradigm shift, changing from owning to sharing and from manufacturing to service. However, it is hard to conclude that the economic value of smart mobility service is always positive to users. Cost related to owing or share a vehicle is very hard to estimate from the perspective of potential users as well as the benefit of the service. Focusing on the cost side of the story, this study develops a cost estimating model based on three main factors: electrification, advanced driving assistant systems (ADAS) function, and participation of ride-sharing service. As a result of the model analysis, low cost was estimated as a result when receiving cost benefits such as electrification and ride-sharing participation. Various factors were analyzed through sensitivity analysis also. These results can provide useful insights into the cost prediction and strategies for potential users and manufacturers on smart mobility service market.

• Journal of Advanced Navigation Technology
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• v.28 no.4
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• pp.472-479
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• 2024

Half of the world's total population lives in cities, continuous urbanization is progressing, and the urban population is expected to exceed two-thirds of the total population by 2050. To resolve this phenomenon, the Korean government is focusing on building a new urban air mobility (UAM) industrial ecosystem. Airlines are also part of the UAM industry ecosystem and are preparing to improve efficiency in safe operations, passenger safety, aircraft operation efficiency, and punctuality. This study performs demand forecasting using time series data on the number of daily passengers on Korean Air's Gimpo to Jeju route from 2019 to 2023. For this purpose, statistical and machine learning models such as SARIMA, Prophet, CatBoost, and Random Forest are applied. Methods for effectively capturing passenger demand patterns were evaluated through various models, and the machine learning-based Random Forest model showed the best prediction results. The research results will present an optimal model for accurate demand forecasting in the aviation industry and provide basic information needed for operational planning and resource allocation.

• Journal of the Korea Society for Simulation
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• v.7 no.2
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• pp.63-78
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• 1998

The hierarchical cell structure consists of the macrocell and microcells to increase the system capacity and to achieve broad coverage. The hierarchical cell structure provides services for users in different mobility. In this paper, an analytical queueing model in mobile networks is proposed for the performance evaluation of the hierarchical cell structure. The model for networks with the multiple levels can simplify multi-dimensional ones into one-dimensional queueing model. The computational advantage will be growing as the layers are constructed in multiple levels. The computer simulation is provided for validating the proposed analytical model.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.07a
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• pp.7-8
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• 2016

Ad-hoc 네트워크 기술이 발달함에 따라 FANET(Flying Ad-Hoc Notworks)을 이용한 그룹 무인기 정찰이 요구되고 있다. 본 논문에서는 자율비행을 위한 효율적인 그룹 무인기 정찰을 위하여 새로운 이동성 모델을 제안한다. 제안하는 모델은 Random Waypoint에 기반 하는 모델로써 정찰되지 않은 구역의 선택 확률을 높여 균형적 탐색을 유도한다. 시뮬레이션을 이용하여 제안하는 모델이 기존의 Random Waypoint 에 비해 80% 정찰비율 시간 향상 면에서 우수함을 보인다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.11 s.254
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• pp.1486-1493
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• 2006

This paper presents a dynamic model of a high mobility tracked vehicle composed of rigid bodies. Track is modeled as an extensible cable and the track tension between the sprocket and roller is calculated by the catenary equation. The ground force acting on a road wheel is calculated by the Bekker's pressure-sinkage relationship using the segmented wheel model. System equations of motion and constraint acceleration equations are derived in the joint coordinate space using the velocity transformation method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.378-384
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• 2008

This Paper presents dynamic analysis of HVAC(Heating Ventilation & Air Condition) Heater Case which consists of heater and evaporator unit for passenger car. To analyze the dynamic characteristics of HVAC Heater Case. finite element model which consists of shell elements is constructed for modal analysis and experimental Modal analysis has been conducted. Finite element analysis results are compared with experimental results to evaluate of validity of finite element model After identifying node shape and natural frequency of HVAC Heater Case, local stiffness of HVAC Case is evaluated through point mobility using finite element analysis and experiment.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1644-1651
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• 1989

In this paper, a two-dimensional numerical analysis of HEMT's with gate length of 0.6um is performed. In this case, Control Volume Formulation method which has been used in the analysis of heat transfer and fluid flow is used as a numerical method. As a mobility model, empirical formula including the velocithy overshoot phenomena is used instead of two-piece mobility model. The results obtained from this numerical analysis(i.e., the region in which cahnnel is formed, the strength of electric field in the channel, the distribution of potential, and the distribution of electron concentration etc.)are in good agreement with the previous analytic results. And our results also show the parasitic MESFET's operation in the range of the high gate voltage.

• Journal of Korea Multimedia Society
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• v.7 no.1
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• pp.106-112
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• 2004

Mobile IP is a solution for mobility on the global Internet. However, it causes service delay incase of frequent movement of mobile node and mobile users. Mobile IP regional registration is Proposed to reduce the service delay. In this paper, we introduce an optimal regional location management mechanism for Mobile IP that reduces the registration delay. The movement of mobile node is described by a discrete analytical model. The proposed model explains analytically average packet rate and registration cost as the size of regional networks with mobility of mobile node.