• Journal of Power Electronics
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• v.16 no.6
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• pp.2024-2034
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• 2016

This paper presents a DC-DC buck converter with a Phase-Locked Loop (PLL) that can compensates for power efficiency degradation over a wide input range. Its switching frequency is kept at 2 MHz and the delay difference between the High side driver and the Low side driver can be minimized with respect to Process, Voltage and Temperature (PVT) variations by adopting the PLL. The operation mode of the proposed DC-DC buck converter is automatically changed to Pulse Width Modulation (PWM) or PWM frequency modes according to the load condition (heavy load or light load) while supporting a maximum load current of up to 1.2 A. The PWM frequency mode is used to extend the CCM region under the light load condition for the PWM operation. As a result, high efficiency can be achieved under the light load condition by the PWM frequency mode and the delay compensation with the PLL. The proposed DC-DC buck converter is fabricated with a $0.18{\mu}m$ BCD process, and the die area is $3.96mm^2$. It is implemented to have over a 90 % efficiency at an output voltage of 5 V when the input range is between 8 V and 20 V. As a result, the variation in the power efficiency is less than 1 % and the maximum efficiency of the proposed DC-DC buck converter with the PLL is 95.4 %.

• Korean Journal of Construction Engineering and Management
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• v.18 no.5
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• pp.50-58
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• 2017

The efficient communication process is essential to guarantee the completeness of design and secure the quality to meet the contractor's needs. However, using the existing communication methods based on the design and documents, it is difficult to effectively understand the drawings and specifications that are very complicated, and sufficient technical experiences would be required. Ineffective and inefficient communication among users, designers and project participants during the design process would raise the possibility of functional interferences of the object, induce conflicts, cause a design change, and accordingly incur losses of the project in terms of cost and time. The purpose of this study is to suggest improvement direction of communication in accordance with the requirements, by investigating the present state and the project participants' understanding of design communication. And also, it presents the application model of QFD that the project participants could share and define, and feedback the requirements as well as conducting analysis of improvement factors based on the survey.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.5
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• pp.73-81
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• 2011

Considering education process in university, We will have consensus about that has not satisfied exactly individual student's needs. Because education in university has the process that one person contract diverse many people in same time. So, we consider about that if students have used more information communication technology, they have more satisfaction in education process and contents. Our research verify these hypotheses that students' high degree of technology acceptance tendency affect degree of relationship quality, education service quality, and education service satisfaction to be high. And these relationship are affected by level of students' using information communication technology. As a results, if students have high degree of technology acceptance then they have high degree of relationship quality, education service quality, and education service satisfaction. Also, enough students to use information and communication technology has moderate effect about these relationship. This study was conducted at university is located in the province's small and medium-sized cities. Therefore, future training will utilize its contents have been more effective.

• Journal of Korea Multimedia Society
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• v.20 no.12
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• pp.1960-1969
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• 2017

There have been ongoing researches to identify and analyze the patterns of electric power IoT data inside sensor nodes to supplement the stable supply of power and the efficiency of energy consumption. This study set out to propose an analysis process for electric power IoT data with the K-means algorithm, which is an unsupervised learning technique rather than a supervised one. There are a couple of problems with the old K-means algorithm, and one of them is the selection of cluster number K in a heuristic or random method. That approach is proper for the age of standardized data. The investigator proposed an analysis process of selecting an automated cluster number K through principal component analysis and the space division of normal distribution and incorporated it into electric power IoT data. The performance evaluation results show that it recorded a higher level of performance than the old algorithm in the cluster classification and analysis of pitches and rolls included in the communication bodies of utility poles.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.5
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• pp.33-38
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• 2016

In Android platform, as applications invoke various service functions through IPC (Inter-Process Communication), IPC performance is critical to the responsiveness in Android. However, Android offers long IPC latency of hundreds of micro-seconds due to complicated software stacks between the kernel Binder and the user-level process Context Manager. This separation provides modularity and flexibility, but degrades the responsiveness of services owing to additional context switching and inefficient request handling. In this paper, we anatomize Android IPC mechanisms and observe that 55% of IPC latency comes from the communication overhead between Binder and Context Manager. Based on this observation, this paper proposes a kernel Binder cache that retains a popular subset of service function mappings, thereby reducing the requests transferred to the user-level daemon. The proposed Binder cache is implemented in Android 5.0 and experimental results with various benchmarks show that the proposed cache architecture improves performance by 52.9% on average.

• Proceedings of the Korea Society for Simulation Conference
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• 1994.10a
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• pp.32-32
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• 1994

In this example, a message passing based multicomputer system with general interdonnedtion network is considered. After multicomputer systems are developed with morm-hole routing network, topologies of interconecting network are not major considertion for process management and resource sharing. Tehre is an independeent operating system kernel oneach node. It communicates with other kernels using message passingmechanism. Based on this architecture, the problem is how mech does performance degradation will occur in the case of processor sharing on multicomputer systems. Processor sharing between application programs is veryimprotant decision on system performance. In almost cases, application programs running on massively parallel computer systems are not so much user-interactive. Thus, the main performance index is system throughput. Each application program has various communication patterns. and the sharing of processors causes serious performance degradation in hte worst case such that one processor is shared by two processes and another processes are waiting the messages from those processes. As a result, considering this problem is improtant since it gives the reason whether the system allows processor sharingor not. Input data has many parameters in this simulation . It contains the number of threads per task , communication patterns between threads, data generation and also defects in random inupt data. Many parallel aplication programs has its specific communication patterns, and there are computation and communication phases. Therefore, this phase informatin cannot be obtained random input data. If we get trace data from some real applications. we can simulate the problem more realistic . On the other hand, simualtion results will be waseteful unless sufficient trace data with varisous communication patterns is gathered. In this project , random input data are used for simulation . Only controllable data are the number of threads of each task and mapping strategy. First, each task runs independently. After that , each task shres one and more processors with other tasks. As more processors are shared , there will be performance degradation . Form this degradation rate , we can know the overhead of processor sharing . Process scheduling policy can affects the results of simulation . For process scheduling, priority queue and FIFO queue are implemented to support round-robin scheduling and priority scheduling.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.219-226
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• 2018

IIoT(Industrial Internet of Thing) means that all manufacturing processes are informed beyond the conventional automation of process automation. The objective of the system is to build an information system based on the data collected from the sensors installed in each process and to maintain optimal productivity by managing and automating each process in real time. Data collected from sensors in each process is unstructured and many studies have been conducted to collect and process such unstructured data effectively. In this paper, we propose a system using Node-RED as middleware for effective big data collection and processing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.305-307
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• 2021

In this paper, we propose a study related to the development of a Digital-Twin platform using a smart factory based CPPS (Cyber Pysical Production System) using ICT (Information Communication Technology) technology. The platform developed through this study performs a 3D model simulation function in conjunction with P3R (Product, Process, Plant, Resource) including BOP (Bill of Process) management function from the preceding manufacturing process planning stage. In addition, we propose a digital twin platform that can predict production processes, equipment, layout, and production. The platform proposed through this paper proposes a feature that can manage the entire smart factory manufacturing process from the initial planning design stage to the manufacturing, production, operation, and maintenance stages.

• 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 Industrial Technology
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• v.17
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• pp.95-101
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• 1997

A smart pressure measurement system is described, which provides a precise A/D conversion and is highly suitable for communication with microprocessors. In order to avoid unstable problems of remote pressure sensing we have developed a new interface board which performs the A/D conversion and smart signal processing of the measured pressure data. Serial communication software which is based on ASCII code commands is also developed to process initial setup and calibration functions as well as multi-drop communication with PC. The test and evaluation of the proposed system has been shown as having the better performance compared to the other types of existing pressure measuring systems and will give good applications to the industrial use where a highly precision remote sensing is needed.