• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.257-262
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• 2000

Recently, though there are many REES(Remote Education Estimation Systems), they have some tied and complete testing method not considering for the student individual specification and characteristic. This paper proposes the education model of the distributed asynchronous communication method which making a test without me and place limits using web estimation system from problem bank database, and attach effective method could improve student achievement, quality of estimation later problem filtering using user profile in order to consider the student individual difference and characteristic that not considered pre-Remote Education Estimation Systems. This is a adaptive DAC method improving the pre-DAC method.

• Journal of Information Science Theory and Practice
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• v.6 no.1
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• pp.45-64
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• 2018

The global information economy is transforming the way people connect with each other, learn new things, and contribute to the knowledge society. With the online platform, library services have also expanded beyond face to face interaction. Although studies of virtual reference services have been made in different parts of the world, a case study discussing various forms of online reference engagement in Kazakhstan has not been written. While most of the theories on connectivism emphasize the context of instruction, the researchers of this paper discussed the tenets as they relate to online engagement. Applying the theory of connectivism, this paper explores through a mixed method the use of various online platforms to enhance engagement connecting library users to information. Findings revealed that differences in patterns of interactions as to platforms, types of queries, and users reveal that students, faculty, and other members of the academic community served by the library have various preferences for communication. The case study further showed that respondents have not maximized the use of VLS but interest in using both synchronous and asynchronous services is clear. Finding connections between sources of information, creating useful information patterns, is essential in learning. Amplifying awareness on the use of VLS giving emphasis to the unique features of each service is useful in order to enable students to see how this platform facilitates learning.

• Journal of Platform Technology
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• v.9 no.2
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• pp.3-9
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• 2021

The management of sensor information requires the functions for registering, modifying and deleting rapidly sensor information about various many sensors. In this research, Celery and MongoDB are used for developing a sensory data management system. Celery supplies a queue structure based on asynchronous communication in Python. Celery is a distributed simple job-queue but reliable distributed system suitable for processing large message. MongoDB is a NoSQL database that is capable of managing various informal information. In this experiment, we have checked that variety of sensor information can be processed with this system in a IoT environment. To improve the performance for handling a message with sensory data, this system will be deployed in the edge of a cloud infrastructure.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.91-96
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• 2019

There are so many low power MAC protocols for wireless sensor network. IEEE802.15.4 among them has disadvantage of a large power consumption for synchronization. To save power consumption it use the superframe operation alternating sleep mode and awake mode. But latency is longer result from superframe operation. Typical asynchronous B-MAC can have shorter latency according to check interval. But transmitter consumes more power because of long preamble. And receiver is suffering from overhearing. In this paper, we propose the adaptive check interval scheme of B-MAC for enhancing the power consumption and delay latency performance. Its power consumption is evaluated by comparing the proposed scheme with a typical IEEE802.15.4.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.63-72
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• 2021

Mobile crowd-sensing (MCS) is a promising sensing paradigm that leverages mobile users with smart devices to perform large-scale sensing tasks in order to provide services to specific applications in various domains. However, MCS sensing tasks may not always be successfully completed or timely completed for various reasons, such as accidentally leaving the tasks incomplete by the users, asynchronous transmission, or connection errors. This results in missing sensing data at specific locations and times, which can degrade the performance of the applications and lead to serious casualties. Therefore, in this paper, we propose a missing data inference approach, called missing data approximation with probabilistic tensor factorization (MDI-PTF), to approximate the missing values as closely as possible to the actual values while taking asynchronous data transmission time and different sensing locations of the mobile users into account. The proposed method first normalizes the data to limit the range of the possible values. Next, a probabilistic model of tensor factorization is formulated, and finally, the data are approximated using the gradient descent method. The performance of the proposed algorithm is verified by conducting simulations under various situations using different datasets.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.162-169
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• 2022

Arduino is used in various places such as education, experimentation, and industry. Due to the easy accessibility of Arduino, it is often used by non-majors, and it is also used in media art and toy programs. Although Arduino is relatively easy to use compared to other devices, it is not easy to control various IoT components at the same time. Some tasks run independently of other tasks, while others run dependently. In this paper, I proposed the Arduino Task Framework to efficiently execute many tasks in these various situations. The design framework of this paper is largely composed of two types: synchronous execution and asynchronous execution. These two execution methods can be combined to create several independent and dependent execution routines. Asynchronous tasks are independently executed tasks and are managed by AsyncTaskGroup, while synchronous tasks are dependently executed tasks and are managed by SyncTaskGroup. AsyncTaskGroup instance and SyncTaskGroup instance are instances of the same Task and can be used in combination with another task. The Arduino framework proposed in this paper simplifies the program structure and can easily compose various tasks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.1
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• pp.129-134
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• 2014

This paper presents a 10-bit 10-MS/s asynchronous successive approximation register (SAR) analog-to-digital converter (ADC) which consists of a digital-to-analog converter (DAC), a SAR logic, and a comparator. The designed asynchronous SAR ADC with a rail-to-rail input range uses a binary weighted DAC using metal-oxide-metal (MOM) capacitor to improve sampling rate. The proposed 10-bit 10-MS/s asynchronous SAR ADC is fabricated using a 0.18-${\mu}m$ CMOS process and its active area is $0.103mm^2$. The power consumption is 0.37 mW when the voltage of supply is 1.1 V. The measured SNDR are 54.19 dB and 51.59 dB at the analog input frequency of 101.12 kHz and 5.12 MHz, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.414-422
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• 2013

This paper describes a 10-bit 10-MS/s asynchronous successive approximation register (SAR) analog-to-digital converter (ADC) using a split-capacitor-based differential digital-to-analog converter (DAC). SAR logic and comparator are asynchronously operated to increase the sampling frequency. The time-domain comparator with an offset calibration technique is used to achieve a high resolution. The proposed 10-bit 10-MS/s asynchronous SAR ADC with the area of $140{\times}420{\mu}m^2$ is fabricated using a 0.18-${\mu}m$ CMOS process. Its power consumption is 1.19 mW at 1.8 V supply. The measured SNDR is 49.95 dB for the analog input frequency of 101 kHz. The DNL and INL are +0.57/-0.67 and +1.73/-1.58, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.11
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• pp.2021-2026
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• 2007

In the parer, we design a non-coherent UWB system by adopting the architecture of a simplified asynchronous transmission and the edge-triggered pulse transmission, which makes e system performance independent of the share of the transmitted waveform, robust to multipath channels. The designed non-coherent UWB transceiver architecture has an advantage of the simple realization since any mixer, high-speed correlator, and high-sampling A/D converter are not necessary at the cost of performance degradation of about 3dB. Further, the designed non-coherent UWB transceiver is actually implemented with the wireless CANVAS prototype testbed in short range indoor application environments such as a lecture room. The implemented prototype testbed is proven to offer the data rate of 115kbps on the conditions of Peer-to-Peer(P-to-P) in the indoor channel within the range of about 10m.

• Journal of Internet Computing and Services
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• v.6 no.6
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• pp.23-34
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• 2005

In a large scale parallel computation, failures of some nodes or communication links end up with waste of computing resources, Several fault-tolerant MPI libraries have been proposed so far, but the programs written by using such libraries have a portability problem since fault-tolerant features are not supported by the MPI standard yet, In this paper, we propose an application-level fault-tolerant linear system solver that uses the asynchronous iteration algorithm and the standard MPI functions only, which does not have a portability problem and is more efficient by adopting a simplified recovery mechanism.