• The Transactions of the Korea Information Processing Society
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• v.4 no.8
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• pp.2106-2119
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• 1997

NDAS(Network Data Access System) is a system that interconnects high speed network(B-ISDN) and Local Area Network(Ethernet, FDDI). Nowadays, the request of multimedia data increases rapidly, so NDAS system must accept and process that request efficiently. Comparing with normal data traffic characteristics, multimedia data traffic characteristics are much complex, so it is necessary to implement the system that can cover such factor. In this paper, we suggest a NDAS hardware system model and also we propose a proper buffer size of NDAS system through the simulation. For measuring the proper buffer size of NDAS, we assumed two different simulation models, one is the case of using only one buffer and the other is the case of using two different buffers for Ethernet and FDDI, respectively. After comparing and analyzing simulation results, we suggest the proper NDAS system buffer size.

• Journal of Information Management
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• v.41 no.4
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• pp.69-91
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• 2010

Libraries are encountering hostile conditions around journal licensing such as limited budget, the high price of packages, and vendor-led negotiation. They need to collect and analyze usage data of electronic journals to develop electronic journal collection appropriate for their own circumstances. The purpose of this study is to suggest an practical guideline for librarians' analysis of electronic journal usage statistics. For this, the study reviewed related previous studies and examined current state on usage statistics provided from COUNTER release 3 compliant vendors. Finally this study proposed five core statistics including full-text article request per journal, journal using rate, price per full-text article request, most use group, and low use group, and further discussed how to use them effectively for the electronic journal management.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.105-108
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• 2004

다단계 보안데이터베이스 시스템에서 기본적인 병행수행 제어 기법들은 비밀채널과 교착상태등과 같은 문제들이 발생하였다. 이에 직렬화 순서를 동적으로 재조정함으로서 해결하려는 방안이 있었지만, 알고리즘의 복잡성으로 인해 오버 헤드와 많은 수행시간이 필요하게 되었고, 이에 따라 많은 양의 시스템 자원과 높은 사양의 시스템을 요구하게 되었다. 또한 이러한 방법은 다중 버전을 사용함으로서 추가적인 관리비용이 높게 되었고, 각각의 트랜잭션이 지연 및 재수행이란 불필요한 과정을 반복하게 되었다. 따라서 본 논문에서는 제안한 알고리즘은 데이터베이스의 용도에 맞게 직렬화 순서를 보장하여 스케줄을 관리하는 요청 2단계 로킹기법(Request Two-phase Locking)으로서 이는 2단계 로킹기법의 기본원리에 요청로크를 사용함으로 보다 효율적으로 병행제어를 할 수 있다. 여기서 요청로크는 각각의 트랜잭션 스케줄에 로크획득 및 해제를 병행수행제어의 필요에 따라 유동적으로 할 수 있으며, 읽기로크, 쓰기로크, 요청로크라는 3가지 로킹모드를 통해 대처방안을 마련함으로서, 충돌을 방지하며, 충돌연산의 특성에 따라 직렬화 순서를 동적으로 조정함으로 블록킹을 막는 병행제어를 응용하여 병렬성을 유지한다.

• Journal of the Korea Society of Computer and Information
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• v.24 no.8
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• pp.9-17
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• 2019

In this paper, we propose a block mapping technique applicable to NAND flash memory. In order to use the NAND flash memory with the operating system and the file system developed on the basis of the hard disk which is mainly used in the general PC field, it is necessary to use the system software known as the FTL (Flash Translation Layer). FTL overcomes the disadvantage of not being able to overwrite data by using the address mapping table and solves the additional features caused by the physical structure of NAND flash memory. In this paper, we propose a new mapping method based on the block mapping method for efficient use of the NAND flash memory. In the case of the proposed technique, the data modification operation is processed by using a blank page in the existing block without using an additional block for the data modification operation, thereby minimizing the block unit deletion operation in the merging operation. Also, the frequency of occurrence of the sequential write request and random write request Accordingly, by optimally adjusting the ratio of pages for recording data in a block and pages for recording data requested for modification, it is possible to optimize sequential writing and random writing by maximizing the utilization of pages in a block.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1011-1016
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• 2020

Rapid change in network topology in high-speed VANET(: Vehicular Ad Hoc Network) is an important task for routing protocol design. Selecting the next hop relay node that affects the performance of the routing protocol is a difficult process. The disadvantages of AODV(: Ad Hoc On-Demand Distance Vector) related to VANET are end-to-end delay and packet loss. This paper proposes the AAODV (Advanced AODV) technique to reduce the number of RREQ (: Route Request) and RREP (: Route Reply) messages by modifying the AODV routing protocol and adding direction parameters and 2-step filtering. It can be seen that the proposed AAODV reduces packet loss and minimizes the effect of direction parameters, thereby increasing packet delivery rate and reducing end-to-end delay.

• Journal of the Korea Society of Computer and Information
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• v.25 no.12
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• pp.17-23
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• 2020

As the number of households with companion animals increases, the demand to monitor the health of companion animals in remote locations far away is increasing. We are going to put a wearable device on a companion animal so that it can monitor the heart beat signal from a remote location. However, the monitoring method using Bluetooth has some disadvantages. it can be accessed only in a short distances. In case of WiFi, large power consumption is the problem. To overcome these issues, we propose a system to reduce power consumption by indirectly receiving a user's request using Bluetooth at a time when the user does not need it, and sending sensor data through WiFi when the user makes a monitoring request.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.6
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• pp.1913-1934
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• 2022

The emergence of technologies like Big data analytics, Industrial Internet of Things, Internet of Things, and applicability of these technologies in various domains leads to increased demand in the underlying execution environment. The demand may be for compute, storage, and network resources. These demands cannot be effectively catered by the conventional cloud environment, which requires an integrated environment. The task of finding an appropriate service provider is tedious for a service consumer as the number of service providers drastically increases and the services provided are heterogeneous in the specification. A service broker is essential to find the service provider for varying service consumer requests. Also, the service broker should be smart enough to make the service providers best fit for consumer requests, ensuring that both service consumer and provider are mutually beneficial. A service broker in an integrated environment named Global Manager is proposed in the paper, which can find an appropriate service provider for every varying service consumer request. The proposed Global Manager is capable of identification of parameters for service negotiation with the service providers thereby making the providers the best fit to the maximum possible extent for every consumer request. The paper describes the architecture of the proposed Global Manager, workflow through the proposed algorithms followed by the pilot implementation with sample datasets retrieved from literature and synthetic data. The experimental results are presented with a few of the future work to be carried out to make the Manager more sustainable and serviceable.

• Journal of Advanced Information Technology and Convergence
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• v.10 no.2
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• pp.49-59
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• 2020

As technologies have been developing, our lives are getting easier. Today we are surrounded by the new technologies such as AI and IoT. Moreover, the word, "smart" is a very broad one because we are trying to change our daily environment into smart one by using those technologies. For example, the traditional workplaces have changed into smart offices. Since the 3rd industrial revolution, we have used the touch interface to operate the machines. In the 4th industrial revolution, however, we are trying adding the speech recognition module to the machines to operate them by giving voice commands. Today many of the things are communicated with human by voice commands. Many of them are called AI things and they do tasks which users request and do tasks more than what users request. In the 4th industrial revolution, we use smartphones all the time every day from the morning to the night. For this reason, the privacy using phone is not guaranteed sometimes. For example, the caller's voice can be heard through the phone speaker when accepting a call. So, it is needed to protect privacy on smartphone and it should work automatically according to the user context. In this aspect, this paper proposes a method to adjust the voice volume for call to protect privacy on smartphone according to the user context.

• Spatial Information Research
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• v.22 no.3
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• pp.59-69
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• 2014

Korea's spatial information companies have been supported by the government due to overcome the weak global competitiveness. This research examines possible causality between the request from the company and the policy support by the government. Structural equation model is used to analyze the recognized competitiveness and the supporting policy. The analysis result shows no statistically significant causality between the company's request and government's support. In other words, the current policies including subsidies, tax incentives, national certificates, and information channels do not impact the global competitiveness of a spatial information company. This research concludes that it is necessity to identify actual weaknesses of the company and to review the efficiency of the supporting policies to overcome those identified weaknesses.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.7
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• pp.837-844
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• 2019

As the demand for video streaming has been rapidly increasing recently, video streaming schemes for increasing the efficiency of radio resource has attracted a lot of attention. In this paper, we propose an adaptive video streaming scheme to enhance the efficiency of video streaming by using receivers' caching capability. The proposed streaming scheme can transmit video data on a broadcast basis even when two clients request different video data, only if specific conditions satisfied, while existing schemes can only transmit video data on a broadcast basis only when two clients request the same video data. In this paper, we mathematically derive the average transmission time of the proposed scheme and the approximation of the average transmission time. The accuracy of the mathematical analysis is verified by simulations. Mathematical analysis and simulation results show that the proposed scheme can significantly reduce the average transmission time, compared to the existing scheme.