• Journal of KIISE:Databases
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• v.34 no.3
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• pp.217-231
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• 2007

Frequent disconnection is connected directly to client's cache consistency problem in Mobile Computing environment. For solving cache consistency problem, research about Invalidation Report is studied. But, existent invalidation report structure comes with increase of size of invalidation report structure and decline of cache efficiency if quantity of data become much, or quantity of updated data increases. Also, while existent method confirms whole cache, invalidation report doesn't support selective listening. This paper proposes TTCI(Timestamp Tree-based Cache Invalidation scheme) as invalidation report structure that solve problem of these existing schemes and improve efficiency. We can make TTCI using timestamp of updated data, composing timestamp tree and list ID of data in updated order. If we utilize this, each client can confirm correct information in point that become own disconnecting and increase cache utilization ratio. Also, we can pare down client's resources consumption by selective listening using tree structure. We experimented in comparison with DRCI(Dual-Report Cache Invalidation) that is existent techniques to verify such efficiency of TTCI scheme.

• The KIPS Transactions:PartC
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• v.10C no.3
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• pp.325-334
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• 2003

In stateless server, if an asynchronous cache invalidation scheme attempts to support local processing of read-only transaction in mobile client/sever database systems, a critical problem may occur ; the asynchronous invalidation reports provide no guarantees of waiting time for mobile transactions requesting commit. To solve this problem, the server in our algorithm broadcasts two kind of messages, asynchronous invalidation report to reduce transaction latency and periodic guide message to avoid the uncertainty of waiting time for the next invalidation report. The asynchronous invalidation report has its own sequence number and the periodic guide message has the sequence number of the most recently broadcast asynchronous invalidation report. A mobile client checks its cache validity by using the sequence numbers of these messages.

• Journal of KIISE:Databases
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• v.30 no.6
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• pp.606-628
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• 2003

Recently, there have been many research efforts reported in the literature that focus on the cache consistency problems of mobile clients resulting from their frequent disconnections with a server in mobile environments. To cope with this problem, a number of methods based on the invalidation report scheme has been proposed. However, these proposed methods are sensitive to the disconnection time of mobile clients and independent of the frequency of data updates in the server. As a result, although the number of data updated in the server is small, the traditional methods can not guarantee the cache consistency of mobile clients if their disconnection time is over the time period the invalidation report is allowed to cover. In this paper, we propose an efficient cache consistency method called CCI(Cost-based Cache Invalidation) for mobile clients that take into account not only the disconnection time but also the frequencies of data updates in the server We also present an in-depth experimental analysis by comparing CCI method with BT(Broadcasting Time stamp) method based on Invalidation Report.

• Journal of KIISE:Information Networking
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• v.27 no.2
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• pp.149-159
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• 2000

In mobile computing environments, invalidation and propagation method based on broadcasting is used to transmit the information for cache maintenance of mobile hosts. Previous researches generally adopted invalidation method that easily adapts to the limited network bandwidth and the frequent disconnection. But the invalidation of frequently accessed data causes the contention on the wireless network with the increasing cache requests. Although the propagation method can reduce the cache requests, the high probability of broken message or loss of message is the main factor that degrades the system performance. To resolve these problems, we propose adaptive cache maintenance scheme that dynamically adjusts the broadcasting ratio of invalidation and propagation, according to the wireless network connection states. The proposed scheme broadcasts the propagation message in stable connection state, so it can reduce the cache requests and server response time. With the decreasing available network bandwidth by the frequent partial disconnection and disconnection, the proposed scheme dynamically increases the broadcasting ratio of the invalidation messages to minimize the broken message or the loss of message probability. Consequently, the proposed scheme resolves the problems which arise in the invalidation or propagation method in mobile computing environments.

• Journal of Arbitration Studies
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• v.21 no.1
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• pp.57-72
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• 2011

According to Japanese Patent Act, the Japanese Patent Office, administrative organization, was authorized to decide validation of patent. However, Supreme Court of Japan held that a court is able to decide the invalidation of patent in 11th April, 2000, which caused the reform of Japanese Patent Act in June 2004. Reformed Patent Act established the article 104-3 and makes it for a court to decide the patentability where there are grounds for a patent invalidation. Through this amendment to the Patent Act, the legislative system to decide the patent validation has been reorganized and furthermore alleged infringer is allowed to argue against the patent validation by making use of infringement litigation procedure through defenses against patent invalidation as well as invalidation trial procedure for to file a request for a trial for patent invalidation to the Japanese Patent Office. That is to say, the article 104-3 was established in the Japanese Patent Act in the wake of Kilby, and thus a court, which is judicial authority, not administrative disposition agency is also able to decide the patent validation. Thus this article discuss how a court, the authority of which only patent infringement cases fell under, has been authorized to arbitrate cases about the patent validation and the decision of the patent validation in a court.

• Journal of KIISE:Databases
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• v.32 no.3
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• pp.315-325
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• 2005

In mobile computing environments, a mobile host caches the data items to use the bandwidth efficiently and improve the response time of transactions. If the data items cached in mobile host are updated in the server, the server broadcasts an invalidation report for maintaining the cache consistency of mobile hosts. However, this method has a problem that the response time of mobile transactions can be long since their commit decision is delayed until receiving the invalidation report from the server In this paper, we propose the USR-MT method for improving the response time of mobile transactions. As the UGR-MT method can make a commit decision by using the data group information before receiving the invalidation report, the response time of mobile transactions can be improved. Also our method can improve the cache's efficiency since it prevents all the contents of a cache from being invalidated in the case that the disconnection of a mobile host is longer than the broadcast period of invalidation report.

• Journal of Internet Computing and Services
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• v.3 no.6
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• pp.79-89
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• 2002

The performance of OCC is very sensitive to the transaction abort rate, Even if the abort probability can be reduced by re-ordering, most of re-ordering schemes have space overhead in maintaining a graph or histories, In this paper, we proposed an efficient re-ordering scheme based on a broadcast invalidation mechanism. Our scheme, called CBI, can reduce the abort probability without space overhead in maintaining a graph or histories, By simulation studies, we showed that CBI reduced the abort rate and unnecessary operations, Additionally, we showed that CBI outperforms not only BTS but also TSH with low space overhead.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.307-309
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• 2001

인터넷 환경의 서버-클라이언트 모델에서 네트웍 부하를 줄이고 시스템 성능을 향상시키기 위한 방법으로 캐쉬가 있다. 모바일 클라이언트의 경우 적은 메모리와 스토리지 용량으로 인하여 캐쉬를 좀 더 효과적으로 다루는 방법이 필요하다. 특히 모바일 클라이언트 내의 캐쉬 된 데이터가 무효화(invalidation)되는 문제는 무선 네트웍의 낮은 대역폭과 불안정상 등의 관점에서 기존의 인터넷 환경과 다르게 접근될 필요가 있다. 또한 모바일 클라이언트는 리소스(배터리) 등의 문제로 인해 항상 네트웍과 지속적으로 연결을 하지 못하므로, 본 연구는 이러한 환경에서 캐쉬 된 데이터의 무효화 문제 해결을 위한 계층적 캐쉬 알고리즘을 제시한다. 서버-클라이언트 사이에 MSS(Mobile Switching Station)모델을 구성하고 AVI-based 알고리즘을 바탕으로 모바일 클라이언트에 대한 무효성 보고 횟수를 최소화하는 방법을 제시한다.

• The Korean Journal of Pain
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• v.29 no.3
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• pp.172-178
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• 2016

Background: This study was designed to assess serum vitamin D status (25-OHD) in the fibromyalgia (FM) patients and to compare it with a healthy control group. It also aimed to investigate the correlation of serum vitamin D level with FM symptom severity and invalidation experiences. Methods: A total of 74 consecutive patients with FM and 68 healthy control participants were enrolled. The eligible FM patients completed the Illness Invalidation Inventory (3*I), the Revised Fibromyalgia Impact Questionnaire (FIQR) and a short-form health survey (SF-12). Venous blood samples were drawn from all participants to evaluate serum 25-OHD levels. Mann-Whitney tests and multiple logistic regression analyses were performed and Spearman's correlations were calculated. Results: 88.4% of FM patients had low levels of serum 25-OHD. FM patients had significantly higher level of serum 25-OHD than the control group ($17.24{\pm}13.50$ and $9.91{\pm}6.47$ respectively, P = 0.0001). There were no significant correlations between serum 25-OHD levels and the clinical measures of disease impact, invalidation dimensions, and health status. Multiple logistic regression analyses revealed that an increased discounting of the disease by the patient's spouse was associated with a 4-fold increased risk for vitamin D deficiency (OR = 4.36; 95% CI, 0.95-19.87, P = 0.05). Conclusions: This study showed that although high rates of vitamin D insufficiency or deficiency were seen among FM patients and healthy non-FM participants, but it seems there was no intrinsic association between FM and vitamin D deficiency. Addressing of invalidation experience especially by the patient's spouse is important in management of FM.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.12
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• pp.958-962
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• 2009

Flash memory, which replaces hard disk recently, has different physical characteristics with hard disk. For the performance of flash memory based storage system, many researches over OS and file system layers has been doing. In this paper, we propose the architecture of flash memory based storage which uses information of page invalidation when file deletion occurs from upper layer. Also, we evaluate the performance of proposed system. Proposed system effectively increases IO performance by using page invalidation information to block merge and wear leveling algorithms.