• Journal of the Korea Convergence Society
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• v.13 no.2
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• pp.223-233
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• 2022

In addition to optimistic bias which can be a biased phenomenon in perceived susceptibility, including illusion of control which is a distorted phenomenon, the current study attempted to demonstrate the influential relationship between these two important variables and COVID 19 personal preventive behaviors and social distancing practice. Conducting Survey utilizing online pannel from Macromill Embrain, the present study performed regression analysis, setting personal preventive behavioral variables such as mask wearing, hand washing, using hand sanitizer as independent variable, and analyzed how these independent variables influence control illusion and optimistic bias. As a result, COVID 19 personal preventive behavior didn't have direct effect on optimistic bias and control illusion except for hand washing. Finding, also, showed that control illusion affected optimistic bias, and the relation between these variables was different depending on demographic variable such as gender and age.

• Journal of Internet Computing and Services
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• v.7 no.6
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• pp.79-86
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• 2006

Many of concurrency control for client-sewer database systems have been proposed and studied in the literature. However, commonly known schemes do not manage to the case of dramatic changes in data contention because the data contention of database systems is changed for each cases. In this paper, we propose o hybrid concurrency control. The proposed scheme uses a optimistic scheme for the first-run transactions and a pessimistic scheme for the second-run transactions. By pre-claiming locks in the second phase, deadlocks which ore possible in pessimistic based concurrency control are prevented in our approach. In addition, the scheme ensures at most one re-execution even if the validation in the optimistic phase fails. By a detailed simulation, this paper examines the behaviors of the Distributed Optimistic Concurrency Control and the proposed scheme. The simulation study shows our scheme outperforms Distributed Optimistic Concurrency Control in our experimental result.

• Journal of Digital Convergence
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• v.16 no.4
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• pp.277-288
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• 2018

This study investigated the correlations of the AIDS knowledge, self-esteem, sense of control, optimistic bias toward AIDS, and condom use in the Chinese male college students. A cross-sectional survey was used, and 307 male students were recruited from anonymous universities in cities of two provinces in China. The data were analyzed according to descriptive statistics, ANOVA, Pearson's correlations. The Chinese male college students had an optimistic bias toward AIDS. The score of AIDS knowledge was 73%, and the self-esteem and sense of control scores were all rated higher than the median. The difference among groups according to grade and age were statistically significant in this study. The self-esteem, sense of control, and optimistic bias toward AIDS showed significant positive correlations, but AIDS knowledge, optimistic bias, and condom use have no correlations. The studies that examine psychological variables with condom use among various groups should be followed in the Chinese context.

• Journal of Digital Convergence
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• v.16 no.1
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• pp.251-262
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• 2018

This study aimed to explore how the AIDS knowledge, self esteem, sense of control and optimistic bias affect condom use among male college students. The survey was done among 323 male students within a university in B city and analyzed according to descriptive statistics, ANOVA, Pearson correlation, and multiple regression analysis. The students had optimistic bias regarding AIDS, and the scores on the AIDS knowledge, self esteem, and sense of control were all rated high. Self esteem and sense of control, sense of control and optimistic bias, sense of control and condom use on sexual intercourse with steady sex partner, condom use on with casual sex partners and with steady sex partner showed significant positive correlation. Self esteem and sense of control were predictors of condom use on sexual intercourse with steady sex partner. Additional studies among various groups should be followed to identify the relationship between variables and condom use.

• Journal of Korea Multimedia Society
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• v.7 no.5
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• pp.633-639
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• 2004

The performance of optimistic concurrency control schemes which are generally used for Mobile computing is very sensitive to the transaction abort rate. Even if the abort probability can be reduced by back-shifting the timestamp from the time of requesting a commit, some transactions continuously perform unnecessary operations after the transactions accessed write-write conflicting data. In this paper, we propose an optimistic protocol that can abort the transactions during the execution phase by using the write notification approach. The proposed protocol enhances the performance of the optimistic concurrency control by reducing the unnecessary operations. In addition, we present a simulation study that compares our schemes with the timestamp based certification scheme. This study shows that our scheme outperforms the timestamp based certification scheme.

• Journal of Korean Academy of Nursing
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• v.38 no.3
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• pp.403-409
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• 2008

Purpose: This study was performed to identify the relationship between optimistic bias about health crisis and health behavior of Korean adults in a crisis of health, and to prepare baseline data for developing a health education and promotion program. Methods: Study subjects were 595 aged from 19 to 64 who live in Korea. Data were collected through questionnaires administered by one interviewer. Descriptive statistics and Pearson's correlation coefficient were calculated using the SPSS program. Results: The average score for optimistic bias about health crisis was 2.69, and that for health behavior was 107.05. The optimistic bias about health crisis showed a significantly positive correlation with health behavior (r=.187, p=.000). Conclusion: To make our results more useful, it is necessary to identity the causal relationship between health attitudes as an explanatory variable and optimistic bias as an outcome variable. In addition, a relatively low score in optimistic bias from this research compared to other studies must be explained through further studies considering unique Korean cultural background. Moreover, research of the relationship between optimistic bias about health crisis and health behavior looking at people who don't have good health behaviors is needed.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.66-68
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• 1998

실시간 데이터베이스 시스템에 있어서 동시성 제어는 제한시간을 달성하기 위한 중요한 요소중의 하나이다. 본 연구에서는 효율적인 실시간 데이터베이스 동시성 제어를 위한 알고리즘을 제안하다. 이 알고리즘은 실시간 데이터베이스에 적합한 낙관적 동시성 제어 기법(Optimistic Concurrency Control)을 근간으로 하며, 종료 트랜잭션의 여유시간(slack time)을 고려하여 좀더 많은 수행 트랜잭션의 마감시간 달성에 목표를 두었다.

• The KIPS Transactions:PartD
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• v.8D no.5
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• pp.543-552
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• 2001

To process transactions in fully replicated database, an atomic broadcast is mainly used. In this case of using atomic broadcast, transactions can be delayed because of the coordinating step among servers before processing the transaction. In this paper, we propose an algorithm to resolve the problem of transaction delay. In the proposed algorithm, the transactions are processed by using the optimistic method. The operations of a transaction are performed in the site that it is submitted and its write operations its updates atomically in all replicated sites. Since the serializability of transaction is ensured by checking the sequence number of transactions in the completion-inspection step.

• Journal of Internet Computing and Services
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• v.7 no.4
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• pp.79-90
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• 2006

Data broadcasting is an efficient method for disseminating data, and is widely accepted in the database applications of mobile computing environments because of its asymmetric communication bandwidth between a server and mobile clients. This requires new types of concurrency control mechanism to support mobile transactions executed in the mobile clients, which have low-bandwidths toward the server. In this paper, we propose an OCC/DTA (Optimistic Concurrency Control with Dynamic Time-stamp Adjustment) protocol that can be efficiently adapted to mobile computing environments. The protocol reduces communication overhead by using client-side validation procedure and enhances transaction throughput by adjusting serialization order without violating transaction semantics. We show that the proposed protocol satisfies data consistency requirements, and simulate that this protocol can improve the performance of mobile transactions in data broadcasting environments.

• Journal of KIISE:Databases
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• v.29 no.6
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• pp.477-491
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• 2002

The broadcast environment has asymmetric communication aspect that is typically much greater communication bandwidth available from server to clients than in the opposite direction. In addition, mobile computing systems generate mostly read-only transactions from mobile clients for retrieving different types of information such as stock data, traffic information and news updates. Since previous concurrency control protocols, however, do not consider such a particular characteristics, the performance degradation occurs when previous schemes are applied to the broadcast environment. In this paper, we propose optimistic concurrency control based on timestamp interval for broadcast environment. The following requirements are satisfied by adapting weak consistency that is the appropriate correctness criterion of read-only transactions: (1) the mutual consistency of data maintained by the server and read by clients (2) the currency of data read by clients. We also adopt the timestamp Interval protocol to check the weak consistency efficiently. As a result, we improved a performance by reducing unnecessary aborts and restarts of read-only transactions caused when global serializability was adopted.