• Journal of the Korean Society of Systems Engineering
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• v.5 no.2
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• pp.63-69
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• 2009

For the effective and efficient system development, it is provided of complex and diverse disciplines, analysis and design, points of views for decisions making, technical information management, assurance of products, and so on to be integrated and ensured. Systems engineering is conducted through a process and is implemented by tools based on relevant methodologies. Systems engineering environment should be provided to support the systems engineering process, method, and tools used on the project. In this paper, the essential environment in performing works in a organization applying systems engineering on the basis of system life cycle was reviewed. The present states on establishment of the systems engineering in Korea Railroad Research Institute were also examined with some reviews of other cases.

• Ocean Systems Engineering
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• v.2 no.1
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• pp.49-68
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• 2012

In this paper, an offshore process front end engineering design (FEED) method is systematically introduced and reviewed to enable efficient offshore oil and gas production plant engineering. An integrated process engineering environment is also presented for the topside systems of a liquefied natural gas floating production, storage, and offloading (LNG FPSO) unit, based on the concepts and procedures for the process FEED of general offshore production plants. Various activities of the general process FEED scheme are first summarized, and then the offshore process FEED method, which is applicable to all types of offshore oil and gas production plants, is presented. The integrated process engineering environment is presented according to the aforementioned FEED method. Finally, the offshore process FEED method is applied to the topside systems of an LNG FPSO in order to verify the validity and applicability of the FEED method.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.863-870
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• 2022

Unsatisfactory urban walking environment stresses urban residents, and may cause mental illness and chronic diseases by reducing walking activities. Therefore, establishing a high-quality walking environment that can promote walking activities in urban residents has emerged as an important issue. The walking environment consists of various components, such as trees, stairs, streetlights, benches, signs, fences, and facilities, and it is essential to understand which components and their settings act as satisfiers or dissatisfiers for pedestrians, to create a better quality walking environment. Therefore, this study investigated pedestrian satisfaction and dissatisfaction as a function of various environmental components through a survey using walking environment images. The results revealed that most of the walking environment components except the braille block and treezone exhibited significant correlations with pedestrian satisfaction. Particularly, safety-related component (e.g., adjacent roads, parked cars, traffic cushions, and car separation), and landscape-related components (e.g., trees and green), as well as the material settings of landscape facilities (e.g., wooden fences, benches, stairs, and walkway surfaces) correlated with pedestrian satisfaction. The results of this study can contribute to the extraction of useful features to evaluate pedestrian satisfaction as a function of the walking environment. The research outcome is expected to assist in the effective arrangement of walking environment components and their settings, which will ultimately contribute to significantly satisfactory walking environment and encourage walking activities.

• Transactions on Electrical and Electronic Materials
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• v.16 no.5
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• pp.241-249
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• 2015

Phase-locked-loops (PLL) have been employed in high-speed data transmission systems like wireless transceivers, disk read/write channels and high-speed interfaces. The majority of the researchers use a charge pump (CP) to obtain high performance from PLLs. This paper presents a review of various CMOS CP schemes that have been implemented for PLLs and the relationship between the CP parameters with PLL performance. The CP architecture is evaluated by its current matching, charge sharing, voltage output range, linearity and power consumption characteristics. This review shows that the CP has significant impact on the quality performance of CP PLLs.

• Transactions on Electrical and Electronic Materials
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• v.17 no.6
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• pp.317-328
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• 2016

Over the past few decades, CMOS current comparators have been used in a wide range of applications, including analogue circuits, MVL (multiple-valued logic) circuits, and various electronic products. A current comparator is generally used in an ADC (analog-to-digital) converter of sensors and similar devices, and several techniques and approaches have been implemented to design the current comparator to improve performance. To this end, this paper presents a bibliographical survey of recently-published research on different current comparator topologies for low-power and high-speed applications. Moreover, several aspects of the CMOS current comparator are discussed regarding the design implementation, parameters, and performance comparison in terms of the power dissipation and operational speed. This review will serve as a comparative study and reference for researchers working on CMOS current comparators in low-power and high-speed applications.

• Transactions on Electrical and Electronic Materials
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• v.18 no.5
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• pp.257-260
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• 2017

In this paper, we present the design of a 4.5 V low dropout (LDO) voltage regulator implemented in the 130 nm CMOS process. The design uses a two-stage cascaded operational transconductance amplifier (OTA) as an error amplifier, with a body bias technique for reducing dropout voltages. PMOS is used as a pass transistor to ensure stable output voltages. The results show that the proposed LDO regulator has a dropout voltage of 32.06 mV when implemented in the130 nm CMOS process. The power dissipation is only 1.3593 mW and the proposed circuit operates under an input voltage of 5V with an active area of $703{\mu}m^2$, ensuring that the proposed circuit is suitable for low-power applications.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2016.09a
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• pp.41-43
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• 2016

• Journal of information and communication convergence engineering
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• v.11 no.3
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• pp.167-172
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• 2013

Recently, mobile communication systems are suffering from exponentially increasing data traffic. As a promising solution to the increase in data traffic, a coordinated multi-point transmission and reception (CoMP) scheme has been proposed. Although a great deal of research has been done on this new technology, the performance of mobile communication systems with CoMP has not been evaluated properly in a typical indoor environment. To address this, we have developed a system-level simulator and evaluated the performance of mobile communication systems with CoMP. Unlike previous works, we have used an actual antenna pattern in our simulator and link-level results are properly taken into account through link-level abstraction. By using a system-level simulator, we have evaluated the performance of mobile communication systems with CoMP in an indoor environment and found that unlike an outdoor cellular environment, CoMP may not improve the performance of overall mobile communication systems in an indoor environment.

• Journal of the Korean Society of Systems Engineering
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• v.20 no.1
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• pp.85-94
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• 2024

As systems become more complex today, verifying the safety of complex systems is becoming increasingly important. However, validation activities using actual systems face limitations in terms of time and cost. To overcome these limitations, the functions, characteristics, and operations of physical assets can be implemented in a virtual environment similar to the real world, allowing for validation through simulations under various scenarios. By performing validation in a virtual environment, iterative tests can be conducted through simulations in a realistic virtual environment without physical models during the conceptual design phase. Tests can also be performed under malfunction conditions or extreme conditions. In this study, we introduce a verification method for railway vehicles in a virtual environment and propose a method of applying virtual verification from a life cycle perspective.

• Journal of Animal Environmental Science
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• v.1 no.1
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• pp.21-38
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• 1995

The objective of this study was to review and analyze the application technologies of electronics and microprocessor for environment control and automated management systems of livestock production of the advanced countries, and to select the appropriate and applicable technologies for our systems among the analyzed. In this study, the environment control systems were analyzed mainly on the poultry production systems and the automated management systems on swine and dairy production systems. According to the results, the advanced technologies reviewed and analyzed could be applicable for designing our animal production systems, if those were modified and remodeled for our situation.