• Journal of KIISE:Databases
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• v.30 no.4
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• pp.397-407
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• 2003

Transactions of updating spatial dta with mobile clients are log transactions because a user disconnected from a server surveys real features and updates them. In this environment, it is appropriate to exploit the optimistic approach based on the validation test in order to control the concurrency of transactions. On the contrary, the pessimistic concurrency control scheme makes transactions wait for a long time due to the lock. In this paper, we propose the surrogate transaction model and implement its manager for the S-S-M(Server-Surrogate PC-Mobile Client) structure which is appropriate for updating spatial data in mobile environments. In the S-S-M structure, the mobile client communicates with the server by the surrogate PC. We extend the validation condition in consideration of spatial relationships between spatial objects in this model. We also present the commit protocol where the user of a surrogate PC adjusts objects of the conflicted surrogate transaction to minimize costs for the abortion of the transaction.

• Journal of Advanced Navigation Technology
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• v.12 no.4
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• pp.357-365
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• 2008

Broadcast is a efficient interactive method between a server and mobile clients via wireless channel and broadcast environments are incarnating as various applications. Most studies have been proposed in broadcast environments deal with read-only mobile transactions, many applications are emerging recently that need to manage the update transactions at mobile clients. So we propose a concurrency control for mobile transactions consisted mainly of update operations in broadcast environments. As an optimistic approach is applied for scheduling update transactions, repetitive aborts of update transactions are occur due to conflict between transactions. To solve this problem update transactions must have been executed with distributed manner, but unnecessary aborts are occur as well because of continuous restart. Thus, in this paper we propose a method that transactions are executed distributed manner and can avoid unnecessary aborts of update transactions. Proposed method has no unnecessary uplink and can save resources of mobile client.

• Journal of KIISE:Databases
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• v.28 no.3
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• pp.512-527
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• 2001

In a client-server spatial database, it is desirable to maintain the cached data in a client side to minimize the communication overhead across a network. This paper deals with the issues of concurrency and consistency of map updates in this environment. A client transaction to update map data is an interactive work and takes a long time to complete it. The map update in a client site may affect the other sites'updates because of dependencies between spatial data stored at different sites. The concurrent updates should be propagated to the other clients as well as the server to keep the consistency of map replicated in a client cache, and also the communication overhead of the update propagation should be minimized not to lose the benefit of caching. The newly proposed cache region locking with CR lock and CX lock controls the update dependency due to spatial relationships. CS lock and COD lock are suggested to use optimistic detection-based approaches for guaranteeing the consistency of cached client data. The cooperative update protocol uses these extended locking primitives and Spatial Relationship-based 2PC (SR-based 2PC). This paper argues that the concurrent updates of cached client spatial data can be achieved by deciding on collaborative updates or independent updates based on spatial relationships.

• The Transactions of the Korea Information Processing Society
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• v.7 no.8
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• pp.2310-2326
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• 2000

Client-server DBMS based on a data-shipping model can exploit e1ient resources effectively by allowing inter-transaction caching. However, inter-transaction caching raises the need of transactional cache consistency maintenancetTCCM protocol. since each client is able to cache a portion of the database dynamically. Deferred locking(DL) is a new detection-based TCCM scheme designed on the basis of a primary copy locking algorithm. In DL, a number of lock ,ujuests and a data shipping request are combined into a single message packet to minimize the communication overhead required for consistency checking. Lsing a simulation model. the performance of the prolxlsed scheme is compared with those of two representative detection based schemes, the adaptive optimistic concurrency control and the caching two-phase locking. The performance results indicate that DL improves the overall system throughput with a reasonable transaction abort ratio over other detection - based schemes.

• Cartoon and Animation Studies
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• s.46
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• pp.63-84
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• 2017

Overwhelming images of vividly colored aircraft flying across the blue sky and steam gushing from massive machines are reminiscent of Japanese animation films, especially of works by master director Hayao Miyazaki. By presenting together steam engines, which are mechanical devices of the Industrial Age in the past, and aircraft of the future age, the director constructs ambiguous space and time. These special time and space constitute nostalgia for past time, with devices called steam engines as a medium, and a longing for science and the future as represented by aircraft. In addition, the anticipation and disappointment, ideals and regrets of humans who see these two from the perspective of the present are projected on the works. This shares the characteristic of the steam punk genre, which seeks to return to the past rather than to face current problems. A subgenre of science fiction (henceforth "sci-fi"), steam punk reflects fundamental skepticism of science and technology and mechanized civilization, which have developed beyond human control. In addition, as works that clearly display such characteristics, director Miyazaki's and < $Nausica{\ddot{a}}$ of the Valley of Wind> can be examined. With spectacles of steam engines and aircraft, these two works enticingly visualize narratives about nature and humans and about the environment and destruction. Such attractiveness on the part of the master director's works has led to support from fans worldwide. However, often in the backgrounds of director Miyazaki's works, which have depicted ideal worlds of nature, environment, and community as highly concentrated fantasies, lie presuppositions of war and the end of the world. As works that are especially prominent in such characteristics, there are and . These two works betray the expectations of the audience by establishing the actual wartime as the temporal background and proceeding toward narratives of reality. Trapped in the ontological identity of the director himself, the war depicted by him projects a subjective and romantic attitude. Such a problem stems also from the ambiguity of the hybrid space and time, which is basic to the steam punk genre. This is because the basic characteristic of steam punk is to transplant past time, which humans were able to control, in the future from a perspective of optimism and longing via steam engines rather than to face current problems. In this respect, steam punk animation films in themselves can be seen as having significance and limitations at the same time.