• Journal of KIISE:Software and Applications
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• v.26 no.1
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• pp.80-80
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• 1999

As Temporal DataBase Systems(TDBSs) manages both the historical versions and the current version of each data item, a temporal transaction may access more data records than atransaction in traditional database systems. Hence, the concurrency control subsystem of temporaldatabase management system should be able to correctly and efficiently detect actual conflicts amongconcurrent temporal transactions while the cost of detecting conflicts is maintained in low levelwithout detecting false conflicts which cause severe degradation of system throughput.In this paper, Two-Level Conflict Detection(TLCD) scheme is proposed for efficient conflictdetection between concurrent temporal transactions in TDBs. In the proposed TLCD scheme, sincechecking conflict between concurrent temporal transactions is performed at two levels, i, e., logicallevel and physical level, conflicts between concurrent temporal transactions are efficiently and correctlydetected,Furthermore, we also evaluate the performance of the proposed TLCD scheme with those oftraditional conflict detection schemes, logical-level conflict detection scheme and physical-level conflictdetection scheme by simulation approach, The result of the simulation study shows that the proposedTLCD scheme outperforms the previous conflict detection schemes with respect to the averageresponse time.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.78-84
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• 2011

In this paper, the switching frequency and THD for the reduction instead of traditional single phase inverter using a new type of central arm of the single phase inverter is proposed. The proposed single phase inverter topology, the existing one to add a arm by two-way central switch 3-level output voltage can be raised and, central arm, especially one or two of the switches by using a switch to the diode current switching algorithm was simplified. During the dead time because of this, depending on the direction of the current level does not appear in any other existing level compared to the inverter output voltage level of the THD has the advantage that less can be. The simulation and experimental results verified the validity of the proposed topology.

• East Asian mathematical journal
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• v.33 no.4
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• pp.333-351
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• 2017

Schools are expected to ultimately moderate the difference of inequality issues among social groups and reduce the achievement gaps. This study investigates this expectation, in particular, how students' mathematics achievements are influenced by their parents' education at the individual level and by collective responsibility for teaching at the school level as well as the interaction of the two. Using a two-level hierarchical linear model, this study indicates that a school collective responsibility has a larger positive effect on students' mathematics achievement when their parents' education level is high. This means that school's collective responsibility accelerates inequity in students' mathematics achievement. Knowing that collective responsibility has less of an effect on students whose parents' education is not high, researchers, schools, and school districts should continue to search for school effects that have more of a positive impact on the relationship between mathematics achievement for students whose parents' education is not high in order to have more equitable results for all students.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.34-41
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• 1996

The purpose of this study is to obtain an effective enclosing method for noise reduction of press machine operating in a manufacturing company located in Taegu region. Noise level of the machine is about 95～120 ㏈ which is higher than legal standards by industrial safety and health law. In this study, two experiments were conducted to achieve the above purpose. In the first experiment in which the effects of three independent variables-type and depth of sound-absorbing materials, and depth of air space-on noise level was investigated, it was found that depth of sound-absorbing materials and air space was significant at $\alpha$ = -0.01. In the second experiment studying relationship between depth of sound-absorbing materials and air space and noise level, it was shown that noise level lowered as depth of sound-absorbing materials and air space became thick. Based on these results, two alternatives of enclosing method adequate for the selected company's noise characteristics were suggested.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.6
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• pp.1007-1019
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• 2015

The determination of the required seawall height is usually based on the combination of wind speed (or wave height) and still water level according to a specified return period, e.g., 50-year return period wind speed and 50-year return period still water level. In reality, the two variables are be partially correlated. This may be lead to over-design (costs) of seawall structures. The above-mentioned return period for the design of a seawall depends on economy, society and natural environment in the region. This means a specified risk level of overtopping or damage of a seawall structure is usually allowed. The aim of this paper is to present a conditional risk probability-based seawall height design method which incorporates the correlation of the two variables. For purposes of demonstration, the wind speeds and water levels collected from Jiangsu of China are analyzed. The results show this method can improve seawall height design accuracy.

• International Journal of Computer Science & Network Security
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• v.22 no.3
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• pp.285-291
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• 2022

WSN is the major component for information transfer in IoT environments. Source Location Privacy (SLP) has attracted attention in WSN environments. Effective SLP can avoid adversaries to backtrack and capture source nodes. This work presents a Two-Level Randomized Sector-based Routing (TLRSR) model to ensure SLP in wireless environments. Sector creation is the initial process, where the nodes in the network are grouped into defined sectors. The first level routing process identifies sector-based route to the destination node, which is performed by Ant Colony Optimization (ACO). The second level performs route extraction, which identifies the actual nodes for transmission. The route extraction is randomized and is performed using Simulated Annealing. This process is distributed between the nodes, hence ensures even charge depletion across the network. Randomized node selection process ensures SLP and also avoids depletion of certain specific nodes, resulting in increased network lifetime. Experiments and comparisons indicate faster route detection and optimal paths by the TLRSR model.

• ETRI Journal
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• v.46 no.4
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• pp.619-632
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• 2024

Medical signal processing requires noise and interference-free inputs for precise segregation and classification operations. However, sensing and transmitting wireless media/devices generate noise that results in signal tampering in feature extractions. To address these issues, this article introduces a finite impulse response design based on a two-level transpose Vedic multiplier. The proposed architecture identifies the zero-noise impulse across the varying sensing intervals. In this process, the first level is the process of transpose array operations with equalization implemented to achieve zero noise at any sensed interval. This transpose occurs between successive array representations of the input with continuity. If the continuity is unavailable, then the noise interruption is considerable and results in signal tampering. The second level of the Vedic multiplier is to optimize the transpose speed for zero-noise segregation. This is performed independently for the zero- and nonzero-noise intervals. Finally, the finite impulse response is estimated as the sum of zero- and nonzero-noise inputs at any finite classification.

• Journal of the Korean Home Economics Association
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• v.33 no.5
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• pp.63-73
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• 1995

Absolute poverty is redefined as biological existence level poverty and relative poverty is also redefinded as 'the state that relatively insufficient compared to the specific society's average living standard under the condition that basic needs on the biological existence level has been satisfied.' Then absolute poverty and relative poverty lies on the same welfare continuum. Therefore these two can be regarded as one unified concept. Theoretical bottom line of poverty is the biological existence level and ceiling is average income. Poverty line for the social policy is to be drawn between ceiling and floor. Using these standard lines three poverty bands are categorized : minimum subsistence level, minimum decency level.

• Journal of Biomedical Engineering Research
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• v.18 no.1
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• pp.79-86
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• 1997

This paper describes the development of portable arousal measurement and analysis system. Skin impedance change which responds to the change of arousal level was detected by the three elctrode constant current method and separated into two components(SIR, SIL). Relationship between Nz, IRI and arousal level was studied and criteria of arousal level control was decided by the sleep study. Measured data with and without warning signal were compared and analyzed.

• Journal of the Korean Data and Information Science Society
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• v.19 no.4
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• pp.1183-1189
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• 2008

The general formulas of the operating characteristic(OC) function, average sample number(ASN) and average outgoing quality(AOQ) for the modified n-level skip-lot sampling plan(MMSkSP2) were derived using Markov chain properties by Cho(2008). In this paper, the OC curve, ASN and AOQ of a reference plan, modified two-level, three-level and five-level skip-lot sampling plans are compared.