• Analyses & Alternatives
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• v.6 no.1
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• pp.35-68
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• 2022

In this paper we define wage premium of college hierarchy as a wage differential among college graduates from different universities within the same graduate cohort and estimate the wage premium of college hierarchy for the three different cohorts: namely, 1982, 1992, and 2002. We utilize a unique data set called Education-Labor Market Lifetime Path Survey, which contains education and labor market information about the three different college graduate cohorts. We find that the wage premium of college hierarchy changes over time for the same cohort. It tends to large right after graduation but decrease with labor market experience. When the test score at the time of college entrance controlled, the wage premium of college hierarchy mostly disappears for the 1992 cohort. But for the 2002 cohort it remains seven years after graduation. The difference in the wage premium of college hierarchy can be explained, at least partly, by the number of colleges, college enrollment ratio, and the relation between college hierarchy and the entrance test score.

• Journal of the Korea Society for Simulation
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• v.19 no.3
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• pp.55-62
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• 2010

This paper studies the problem seeking an efficient operational scheduling for battle ships in the Republic of Korea's navy. The ships' availability means that their main systems such as weapons, navigation and propulsion are in full operational readiness. If some of the major systems are not ready, then the ships should not be available for operations. It is required to maintain a high level availability under the limited resources as it determines the strength of ROK's navy. However, it will result in inefficiencies if some ships are operated without proper maintenance only to improve their availability. Thus, this study suggests the operational scheduling for two squadron ships that considers multiple objectives such as availability, overlapping maintenance, and deviation from available ships in a particular week. We applied NSGA-II algorithm to find better solutions for more efficient scheduling. The experiment result reached an efficient solutions after 1,500 generations. Two efficient operational schedules were compared on the basis of three multiple objectives among them.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.4
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• pp.7-15
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• 2010

This study proposes a rad o resource management scheme to maximize the performance of the LTE(Long Term Evolution) uplink, using SC-FDMA(Single Carrier-Frequency Division Multiple Access). Rather than the single-cell SC-FDMA system the existing studies are mainly concerning, this study focuses on multi-cell system which needs considering the interaction among cells. Radio resource management is divided into two phases, planning and operation phases. The former is for the master eNB(e-NodeB) to allocate RBs(radio bearer) to eNB, the latter for eNB to assign RBs to the mobiles in the cell. For each phase, an optimization model and greedy algorithm are proposed. Optimization models aim to maximize the system performance while satisfying the constraints for both QoS and RB continuity. The greedy algorithms, like generic ones, move from a solution to a neighboring one having the best objective value among neighboring ones. From the numerous numerical experiments, the performance and characteristics of the algorithms are analyzed. This study is expected to play a volunteering role in radio resource management for the multi-cell SC-FDMA system.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.2
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• pp.127-137
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• 2010

A Widget platform is acknowledged to be a next generation intelligent platform that is well suited to Web 2.0 and mobile convergence environments. With prospects of growth, examining users' perceptions of current widgets can be a valuable source of information in setting directions for Widget's future development. This study identifies user interface factors that affect widget usability and investigates a strategic approach to promoting the use of widgets by analyzing user's "intention to use" in connection with the identified interface factors. The experimental results show the consistency, intuition, minimal action, and personalization have a positive(+) effect on perceived ease of use and that personalization and design have a causal effect on perceived enjoyment. Inaddition, perceived ease of use has an influence on perceived enjoyment that, inturn, has a direct influence on intention to use. On the other hand, the hypothesis that perceived ease of use has a direct effect on intention to use was rejected.

• Design Convergence Study
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• v.16 no.5
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• pp.177-190
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• 2017

This research aims to suggest a multimodal non-touch gesture interface design to improve the usability of 3D sculpting task. The task and procedure of design sculpting of users were analyzed across multiple circumstances from the physical sculpting to computer software. The optimal body posture, design process, work environment, gesture-task relationship, the combination of natural hand gesture and arm movement of designers were defined. The preliminary non-touch 3D S/W were also observed and natural gesture interaction, visual metaphor of UI and affordance for behavior guide were also designed. The prototype of gesture based 3D sculpting system were developed for validation of intuitiveness and learnability in comparison to the current S/W. The suggested gestures were proved with higher performance as a result in terms of understandability, memorability and error rate. Result of the research showed that the gesture interface design for productivity system should reflect the natural experience of users in previous work domain and provide appropriate visual - behavioral metaphor.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.939-949
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• 2023

In South Korea, a cloud-based vessel traffic service (Cloud VTS) system integrating the fourth industrial revolution technologies such as cloud and AI is currently under development in contrast to the existing VTS systems. A pilot center for at Busan VTS is being established based on differentiated technology and operational programs. The roles of operators and maintenance personnel who operate the innovative Cloud VTS system must be redefined. Additionally, a demand exists for the development of new educational programs to ensure the smooth operation of the Cloud VTS. Therefore, this study introduces the development details of a Cloud VTS system and explores educational strategies aimed at operators and maintenance personnel to ensure its safe operation.

• Journal of Advanced Navigation Technology
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• v.28 no.3
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• pp.338-347
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• 2024

This paper deals with the study of bird collision avoidance measures in UAM operations from an operator's perspective. Urban air traffic is defined as a next-generation transportation system that uses environmentally friendly electric vertical take-off and landing (eVTOL) aircraft to provide transportation services between key points within and around urban centers. For the successful establishment of the UAM industry, it is necessary to ensure safety issues that determine public acceptance. Among the hazards that can occur in aviation operations, preventing bird collisions in urban environments is a measure that can greatly secure operational safety and public acceptance. In addition to physical measures, procedural control measures are required to prevent bird strikes. In order to ensure the safety of UAM operations, this study aims to provide a direction for the establishment of UAM bird collision prevention measures by categorizing bird collision prevention measures into physical and procedural methods and flight sections such as takeoff, landing, and corridor sections. Through this, we hope to contribute to the improvement of the safety of the urban air traffic operation system.

• Journal of Advanced Navigation Technology
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• v.28 no.2
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• pp.201-209
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• 2024

This study investigates the operational facets of low-density urban air mobility (UAM) from an airline's perspective amid burgeoning concerns about urban congestion in megacities. UAM, employing electric vertical takeoff and landing (eVTOL) technology, emerges as a potential remedy to the challenges of traffic gridlock and environmental degradation. As the UAM market progresses from initial stages to maturity, tailored traffic control systems become paramount. Focused on the context of low-density environments during UAM's inception, this research scrutinizes operational frameworks, essential infrastructure, and likely scenarios. It aims to bolster the safety and efficiency of UAM operations by delving into the specifics of traffic control concepts designed for these unique settings. The study seeks to significantly contribute to optimizing UAM's initial phases, providing insights into crucial operational dynamics for a smoother integration of urban air mobility into contemporary urban landscapes.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.369-378
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• 2024

The aim of this study is to conduct a comparative study on the sustainability of the public pension. While the mainstream view on the sustainability of the public pension presupposes financial sustainability, the original purpose of guaranteeing retirement income has been overlooked. The sustainability of the public pension needs to consider not only financial sustainability, but also various factors such as demographic structure, labor productivity, industrial structure, life cycle of working households, government spending on public pensions, economic growth, and social consensus. With this awareness of the problem, this study conducted a fuzzy set qualitative comparative study in 44 countries, including Korea. As a result of the analysis, it was found that Korea had high financial sustainability for a single year, but relatively low integration related to social consultation and public pension operation, and adequacy such as the degree of guarantee and linkage with other pension systems was also relatively low. The sustainability of the broader public pension should be emphasized not only for financial sustainability, but also for adequacy and integration.

• Korea journal of population studies
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• v.28 no.2
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• pp.1-32
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• 2005

The optimum population of a society or country can be defined as 'the population growth path that maximizes the welfare level of the society over the whole generations of both the present and the future, under the paths allowed by its endowments of production factors such as technology, capital and labor'. Thus, the optimum size or growth rate of population depends on: (i) the social welfare function, (ii) the production function, and (iii)demographic economic interrelationship which defines how the national income is disposed into consumption(birth and education of children included) and savings on the one hand and how the demographic and economic change induced thereby, in turn, affect production capacities on the other. The optimum population growth path can, then, be derived in the process of dynamic optimization of (i) under the constraints of (ii) and (iii), which will give us the optimum population growth rate defined as a function of parameters thereof. This paper estimates the optimum population growth rate of Korea by: specifying (i), (ii), and (iii) based on the recent development of economic theories, solving the dynamic optimization problem and inserting empirical estimates in Korea as the parametric values. The result shows that the optimum path of population growth in Korea is around TFR=1.81, which is affected most sensitively, in terms of the size of the partial elasticity around the optimum path, by the cost of children, share of capital income, consumption rate, time preference, population elasticity of utility function, etc. According to a survey implemented as a follow up study, there are quite a significant variations in the perceived cost of children, time preference rate, population elasticity of utility across different socio-economic classes in Korea, which implied that, compared to their counterparts, older generation and more highly educated classes prefer higher growth path for the population of Korea.