• Journal of Internet Computing and Services
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• v.5 no.1
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• pp.67-84
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• 2004

Real-time database systems (RTDBS) are database systems whose transactions are associated with timing constraints such as deadlines. Therefore transaction needs to be completed by a certain deadline. Besides meeting timing constraints, a RTDBS needs to observe data consistency constraints as well. That is to say, unlike a conventional database system, whose main objective is to provide fast average response time, RTDBS may be evaluated based on how often transactions miss their deadline, the average lateness or tardiness of late transactions, the cost incurred in transactions missing their deadlines. Therefore, in RTDBS, transactions should be scheduled according to their criticalness and tightness of their deadlines, even If this means sacrificing fairness and system throughput, And It always must guarantee preceding process of the transaction with the higher priority. In this paper, we propose an efficient real-time scheduling algorithm (Multi-level EFDF) that alleviates problems of the existing real-time scheduling algorithms, a real-time concurrency control algorithm(2PL-FT) for firm and soft real-time transactions. And we compare the proposed 2PL F[ with AVCC in terms of the restarting ratio and the deadline missing ratio of transactions. We show through experiments that our algorithms achieve good performance over the other existing methods proposed earlier.

• The Transactions of the Korea Information Processing Society
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• v.4 no.5
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• pp.1196-1210
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• 1997

Timestamp-Ordering Prltocol among trancaction scheduling alforithms can cause the priority teversion that a transaction with higher priority is processed after the teansaction the trancaction withe lower priority by assigning timestamp to transactions entering system and scheduling them based on the timestamp.To prevent this reversion,we suggest a data priority-based timestamp ordering prioity within the same timestamp group after grouping teansactions into constant time interval based on entering points.To evaluate the performance of this protocol,we compared the performance of this protocol with that of others after constructing the simulation environment with real time database system.We verified that the performance of proposed protocol is supweior to that of timestamp ordering protocol under the comdition of high load and high data conflicts.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.13 no.2
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• pp.115-123
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• 2018

This study is empirically intended to put forward the modeling and process improvement measures for the SCM capability in small venture firms. The findings are summarized as follows. There were strategic alliance, technological development and centralization in the modeling of strategic planning for supply chain, not the least of which is strategic alliance, followed by centralization and technological development. There were routing scheduling, network integration and third party logistics outsourcing in decision making, not the least of which was network integration. There were customer service management, productivity management and quality management in management control, not the least of which was quality management. And there were order management choice, pricing demand, shipment delivery and customer management in transaction support system, not the least of which was order management choice. As for the above-mentioned findings, to maximize the SCM capability and operate the optimized process in small venture firms, the existing strategic alliances can optimize the quality management and stabilize the transaction support system through the network sharing and integration from the perspective of relevant organizational members' capability and process improvement. And the strategic linkage between firms can maximize the integrated capability of information system beyond the simple exchange relation between electronic data, achieving a differentiated competitive advantage. Consequently, the systematization and centralization for the maximization of SCM capability, including the infrastructure construction based on the system compatibility and reliability for information integration, should be preceded before the modeling of the integrated capability for optimum supply chain and the best process management in the smart era.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1655-1673
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• 2018

Mobile computing environment is subject to the constraints of bounded network bandwidth, frequently encountered disconnections, insufficient battery power, and system asymmetry. To meet these constraints and to gain high scalability, data broadcasting has been proposed on data transmission techniques. However, updates made to the database in any broadcast cycle are deferred to the next cycle in order to appear to mobile clients with lower data currency. The main goal of this paper is to enhance the transaction performance processing and database currency. The main approach involves decomposing the main broadcast cycle into a number of sub-cycles, where data items are broadcasted as they were originally sequenced in the main cycle while appearing in the most current versions. A concurrency control method AOCCRBSC is proposed to cope well with the cycle decomposition. The proposed method exploits predeclaration and adapts the AOCCRB method by customizing prefetching, back-off, and partial backward and forward validation techniques. As a result, more than one of the conflicting transactions is allowed to commit at the server in the same broadcast cycle which empowers the processing of both update and read-only transactions and improves data currency.

• Journal of KIISE:Information Networking
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• v.28 no.2
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• pp.217-228
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• 2001

무선 통신 기술 및 이동 컴퓨터의 성능의 발전함에 따라 이동 컴퓨팅 환경을 단순한 단말기로 사용하기 보다는 독립된 수행 단위로 이용하려는 연구가 활발히 진행되고 있다. 즉 모든 작업을 서버에게 보내어 결과를 기다리는 대신 이동 컴퓨터에서 직접수행할 수 있는 알고리즘이 개발되고 있다. 본 논문에서는 이동 컴퓨터에서의 트랜잭션 수행 알고리즘을 제안한다. 우리는 낙관적인 기법을 채택하였는데 이기법은 (a) 동기화에 필요한 메시지를 적게 필요로 하며 (b) 브로드캐스트 기법의 장점을 얻을수 있다. 브로드캐스트 기법은 최근 많은 수의 클라이언트에게 정보를 전송할 수 있는 수단으로써 많이 연구되고 있다. 그러나 접근하는 데이터간에 충돌이 빈번하게 발생한다면 낙관적 기법은 결국 높은 철회율을 보이게 되며 이는 다시 이동 컴퓨터 자원으로 효율적으로 사용하려는 목적과 반대 결과가 된다. 본 논문에서는 이러한 높은 철회율을 감소시키기 위해 재순서화 개념을 도입하였다. 즉 충돌이 발견될 경우 데이터의 일관성을 침해하지 않는 범위내에서 충돌 순서를 결정하도록 하는 것이다. 특히 읽기-쓰기 트랜잭션에 대해서는 후위-재순서화 개념을 읽기-전용 트랜잭션에 대해서는 전위-재순화 개념(O-Pre)을 제안하였으며 실험에 의하여 성능 향상을 보였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.101-104
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• 2001

데이터베이스에서 트랜잭션의 처리량을 향상시키기 위해서 기존의 문법 위주의 직렬성 이론으로는 단위시간당 처리량을 높이기는 힘든 형편이다. 이를 위하여 이타적 잠금 기법(altruistic locking: AL)은 트랜잭션이 객체를 사용한 다음 더 이상 그 객체를 요구하지 않을 때 다른 트랜잭션들이 그 객체를 로크할 수 있도록 미리 객체에 대한 로크를 해제함으로써 트랜잭션들의 대기시간을 줄이고 처리량을 향상시키기 위한 취지에서 제안된 것이다. 확장형 이타적 잠금(extended altruistic locking: XAL)기법은 AL 을 자취의 확장한 것으로 AL 이 근본적으로 안고 있는 반드시 기부된 객체만을 처리해야 한다는 제약을 완화한 기법이다. 본 논문에서는 분산 데이터베이스 환경하에서 장기 트랜잭션으로 인한 단기 트랜잭션의 대기현상을 최소화하도록 함으로써 동시성 제어의 정도를 높일 수 있는 새로운 확장형 이타적 잠금 기법인 양방향 기부기법(two-way donation locking: 2DL)을 제안하고 기존의 제어기법과 비교하였다. 모의실험에 의한 성능평가 결과 2DL 은 작업 처리율과 트랜잭션의 평균 대기시간 면에서 우수한 결과를 나타내었다.

• The Korean Journal of Archival Studies
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• no.11
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• pp.91-122
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• 2005

Appraisal is a basic archival function that analyzes values of records and determines the eventual disposal of records based upon their archival values. In electronic records environment, however, appraisal is different from traditional appraisal system that mainly is based on paper records. Since electronic records don't have physical entity and strongly depend on computer technologies, archivists fall into various dilemma in appraisal of electronic records. Moreover, because creation environment of electronic records is remarkably complex and diversified, appraisal of electronic records cannot be done until the later stages of the life cycle of the records. In Korea, appraisal system is founded on the Tables of Transaction for Records Scheduling through which disposal activities of all records are definite in a concrete form. However, there are little institutional infrastructures associated with appraisal of electronic records. Therefore this paper will intend to analyze characteristic features about appraisal of electronic records as a preliminary study for establishing appraisal system of electronic records in Korea. For this purpose, I have firstly compared creation environment of electronic records with traditional creation environment mainly based on paper records, and analyzed differences between appraisal of electronic records and traditional appraisal system based on paper records in view of recordness of electronic record. then I have examined functional appraisal that focuses on functions and activities in which the records are created and used, and discussed about main issues in relation to establishing appraisal system of electronic records.

• The Korean Journal of Archival Studies
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• no.6
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• pp.3-40
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• 2002

Appraisal is a basic archival function that analyzes values of records and determines the eventual disposal of records based upon their archival values. In Korea, this appraisal concept introduces in earnest through Public Records and Archives Act(PRA, 공공기관의 기록물관리에관한법률) with which Korean record management systems settle inflexibly. In theoreical and methodological area, therefore, it is necessary to analyze appraisal system in this Act with it in archival science. In PRA Act, appraisal system is founded on the Tables of Transaction for Records Scheduling(TRS, 기록물분류기준표) through which disposal activities of all records are definited in a concrete form. In this system, selection of archival materials which has been recognized as a important function of record center is carried out by record creators and archival institutions; Primary value between semi-currenty and non-currenty are reflected at the same time. In view of values, this appraisal system intends to separate reasonably consideration for continuing utility of achives from current use of records throughout agencies duration. Ultimately, appraisal based upon TRS makes up not separated management course but organic courses reflecting the Continuum of Care. Of course, this appraisal system makes up the deficiency partially. TRS regarded as 'mainboard' of current appraisal system will have to be enacted elaborately. And appraisal strategies of electronic records must set up in detail in PRA Act and TRS. Lastly, arrangement and description concepts immanent in TRS will have to supplement in archival institutions.

• The KIPS Transactions:PartD
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• v.9D no.2
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• pp.235-242
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• 2002

We propose an advanced transaction scheduling protocol for concurrency control of multilevel secure databases in wireless mobile network environment. Wireless communication is characterized by frequent spurious disconnections. So short-lived transaction must quickly access database without any delay by long-lived one. We adapted two-phase locking protocol, namely traditional syntax-oriented serializability notions, to multilevel secure databases in wireless mobile network environment. Altruistic locking, as an advanced protocol, has attempted to reduce delay effect associated with lock release moment by use of the idea of donation. An improved form of a1truism has also been deployed for extended a1truistic locking. This is in a way that scope of data to he early released is enlarged to include even data initially not intended to be donated. Our protocol is based on extended altruistic locking, but a new method, namely bi-directional donation locking for multilevel secure databases (MLBiDL), is additionally used in order to satisfy security requirements and concurrency. We showed the Simulation experiments that MLBiDL outperforms the other locking protocols in terms of the degree of throughput and average waiting time.

• The KIPS Transactions:PartD
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• v.8D no.1
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• pp.24-31
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• 2001

In this paper, we present an advanced transaction scheduling protocol to improve the degree of concurrency and satisfy the security requirements for multilevel secure database. We adapted two-phase locking protocol, namely traditional syntax-oriented serializability notions, to multilevel secure database. Altruistic locking, as an advanced protocol, has attempted to reduce delay effect associated with lock release moment by use of the idea of donation. An improved form of altruism has also been deployed for extended altruistic locking OffiLl. This is in a way that scope of data to be early released is enlarged to include even data initially not intended to be donated. We also adapted XAL to multilevel secure database and we first of all investigated limitations inherent in both altruistic schemes from the perspective of alleviating starvation occasions for transactions in particular of short-lived nature for multilevel secure database. Our protocol is based on extended altruistic locking for multilevel secure database (XAL/MLS), but a new method, namely two-way donation locking for multilevel secure database (2DL!/-MLS), is additionally used in order to satisfy security requirements and concurrency. The efficiency of the proposed protocol was verified by experimental results.