• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.3
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• pp.61-69
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• 2019

The concept of carsharing involves sharing a small number of reserved cars to be used individually by a larger number of people as required. This study examines the operating parameters of one-way carsharing systems in order to determine the appropriate operating conditions that minimizes the lost sales rate. Five operating parameters are tested in this study: the number of stations, the average number of vehicles per station, the rate of one-way trip, the average number of staffs per station, and the relocation policy. The performance of round-trip carsharing systems is also compared to that of one-way carsharing systems. A simulation model is developed and simulations are performed to determine the appropriate combination of operating parameter and levels. The simulation results show that the average number of vehicles per station is the most critical parameter. Other key findings obtained from this research are as follows. First, applying the appropriate relocation policy to one-way carsharing systems can allow more customers to rent vehicles than the traditional round-trip carsharing systems. Second, the appropriate relocation policy should be selected based on the average number of vehicles per station in order to minimize the lost sales rate. Third, the number of stations does not affect the lost sales rate. This study findings will provide tools to understand impact of the carsharing system parameters on the efficiency of the carsharing operations.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1976-1981
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• 2003

Except a desktop computer and workstation, an embedded system is a system containing microprocessors. While a desktop computer and a workstation are designed for a general purpose, an embedded system is designed for a dedicated purpose. Thus, an embedded system must meet some constraints such as low power consumption, low cost, small size, real-time, or user-defined ones. A simple and low cost embedded system may be able to be designed without using embedded operating systems (OS). However, considered design time and effort, some embedded system had better be designed with using embedded OS. Under given constraints and purpose of some embedded systems, one embedded OS can save more time, cost, and effort in designing those embedded systems than others. This paper compares four embedded OSs, Windows CE, Embedded Linux, pSOS, and uC/OS. It analyzes several issues of embedded OS such as process scheduling, inter-process communication (IPC), memory management, and network support. Also, it describes the product of each embedded OS.

• Journal of the military operations research society of Korea
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• v.30 no.1
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• pp.15-29
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• 2004

The existing CSP systems is inefficient and brings about waste of budget in some operating aspects which show accumulation of unnecessary items, omitted or running short items and limitation of timely use of them. The purpose of this study is to analyze the actual situation of existing CSP(calculation and estimation of CSP requirements), and to suggest a few methods (post control system by activating buy-back system, and middle and long term operating system itself in relation to budget) to improve the CSP operating systems in order to maximize the effectiveness of combat strength and to contribute to the economic efficiency of defense management. The results show that improved method is efficient and effective by comparing with some actual data.

• Journal of Korea Multimedia Society
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• v.17 no.12
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• pp.1494-1502
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• 2014

Since smartphones are utilized in the ranges from personal usages to governmental data exchanges, known but not patched vulnerabilities in smartphone operating systems are considered as major threats to the public. To minimize potential security breaches on smartphones, it is necessary to estimate possible security threats. So far, there have been numerous studies conducted to evaluate the security risks caused by mobile devices qualitatively, but there are few quantitative manners. For a large scale risk evaluation, a qualitative assessment is a never ending task. In this paper, we try to calculate relative risk levels triggered by software vulnerabilities from unsecured smartphone operating systems (Android and iOS) among 51 Asian countries. The proposed method combines widely accepted risk representation in both theory and industrial fields. When policy makers need to make a strategic decision on mobile security related agendas, they might find the presented approach useful.

• Journal of the Korea Society of Computer and Information
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• v.27 no.7
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• pp.65-73
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• 2022

Recently, as the Windows system supports the Windows subsystem for Linux (WSL), various researchers have studied to apply a docker container on various systems such as server systems, workstation system and so on. However, in various existing researchers, there is a lack of performance-related indicators to apply the system to each operating system (linux system and windows system). In this paper, we compared a performance comparison and analysis of container-based host operating systems. We configured experimental environments of operating systems for microsoft windows systems and linux systems based on a docker container support. In experimental results, the containers of linux systems reduced the average data latency of dataset 1-6 by 3.9%, 62.16%, 1552.38%, 7.27%, 60.83%, and 1567.2%, compared to the containers on microsoft windows systems.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.9
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• pp.626-633
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• 2006

The wireless sensor networks are sensing, computing and communication infrastructures that allow us to monitor, instrument, observe, and respond to phenomena in the harsh environment. Sensor operating systems that run on tiny sensor nodes are the key to the performance of the distributed computing environment for the wireless sensor networks. Therefore, sensor operating systems should be able to operate efficiently in terms of energy consumption and resource management. In this paper, we present an efficient memory allocation scheme to improve the time and space efficiency of memory management for the sensor operating systems. Our experimental results show that the proposed scheme performs efficiently in both time and space compared with existing memory allocation mechanisms.

• KIISE Transactions on Computing Practices
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• v.21 no.3
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• pp.269-274
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• 2015

As smart device companies such as Google or Apple develop competitive mobile-based automotive operating systems and navigation systems, the range of choice for users in such markets is expanding. Navigation systems equipped with mobile operating systems have increased convenience for users. However, since an API for the POI databases used in navigation systems doesn't exist, the number of applications using POI data is insufficient. In this paper, we designed and implemented system calls for navigation operating systems with a focus on POI search, in order to resolve such limitations. The system calls support set-based POI search functions, and therefore provides solutions to search performance degradation problems caused by false inputs. As a result of performance evaluation, not only did the search performance improve, but there was also no problem in applying APIs in applications.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1336-1342
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• 2022

Risk-informed safety classification of structures, systems and components (SSCs) is very important for ensuring the safety and economic efficiency of nuclear power plants (NPPs). However, previous methods for safety classification of SSCs do not take the plant operating modes or the operational process of SSCs into consideration, thus cannot concentrate on the safety and economic efficiency accurately. In this contribution, a new method for safety classification of SSCs based on the categorization of plant operating modes is proposed, which considers the NPPs operating history to improve the economic efficiencies while maintaining the safety. According to the time duration of plant configurations in plant operating modes, average importances of SSCs are accessed for an NPP considering the operational process, and then safety classification of SSCs is performed for plant operating modes. The correctness and effectiveness of the proposed method is demonstrated by application in an NPP's safety classification of SSCs.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.188-190
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• 2000

Protective Relays are vital components of power systems. The role of the protective relaying device is more important than ever. Therefore, We have investigated the operating trends of protective relay from 1991 to 1999. we anticipate that reliability in the power systems increases by improving design, manufacture, construction technology and maintenance method of the protective relay.

• The Transactions of the Korea Information Processing Society
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• v.7 no.6
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• pp.1810-1817
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• 2000

The purpose of this research is to develop an estimation model for information systems operating costs. Current cost estimation practices and types of sytem management projects have been reviewed an analyses. Typical operating project types of information systems are determined. They are application system operation, help disk operation, network management and operation, and hardware management. For each type of projects, cost factors ar identified and a structure of cost estimation model is defined. Cost estimation models have been constructed and tested by 24 real operation projects data. Statistical analysis shows derived models are statistically significant. User groups' opinion on these draft cost estimation model has been surveyed and summarized. The results of this research can be used as a cornerstone for future research on operating cost estimation, and for cost estimation guideline of information systems operation projects.