• Genomics & Informatics
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• v.4 no.2
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• pp.51-56
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• 2006

In planning a genetic association study, it is necessary to determine the number of samples to be collected for the study in order to achieve sufficient power to detect the hypothesized effect. The case-control design is increasingly used for genetic association studies due to the simplicity of its design. We review the methods for the sample size and power calculations in case-control genetic association studies between a marker locus and a disease phenotype.

• Journal of the Korean Data and Information Science Society
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• v.25 no.5
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• pp.1127-1135
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• 2014

Genome-wide association studies (GWAS) are designed to discover genetic variants such as single nucleotide polymorphisms (SNPs) that are associated with human complex traits. Although there is an increasing interest in the application of GWAS methodologies to population-based cohorts, many published GWAS have adopted a case-control design, which raise an issue related to a sampling bias of both case and control samples. Because of unequal selection probabilities between cases and controls, the samples are not representative of the population that they are purported to represent. Therefore, non-random sampling in case-control study can potentially lead to inconsistent and biased estimates of SNP-trait associations. In this paper, we proposed inverse-probability of sampling weights based on disease prevalence to eliminate a case-control sampling bias in estimation and testing for association between SNPs and quantitative traits. We apply the proposed method to a data from the Korea Association Resource project and show that the standard estimators applied to the weighted data yield unbiased estimates.

• The Journal of the Korean life insurance medical association
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• v.30 no.2
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• pp.16-19
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• 2011

In patents with diabetes, the higher the serum glucose level was, the more cardiovascular events and death were observed. But with a certain kind of group, to control glucose level tightly does not decrease the incidence of these events. Several studies show that intensive glucose control does not gain benefit in patient with long standing, uncontrolled diabetes, especially having previous cardiovascular events, while definitely preventing progression of newly onset of diabetic nephropathy. Whether intensive glucose control increases mortality in high risk group is obscure and needs more studies with longer observation time.

• Journal of The Korean Association of Information Education
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• v.1 no.2
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• pp.57-66
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• 1997

The primary purpose of security mechanisms in a computer systems is to control the access to information. There are two types of access control mechanisms to be used typically. One is discretionary access control(DAC) and another is mandatory access control(MAC). In this study an access control mechanism is introduced for secure access path in security system. The security policy of this access control is that no disclosure of information and no unauthorized modification of information. To make this access control correspond to security policy, we introduce three properties; read, write and create.

• Journal of Korean Society of Forest Science
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• v.101 no.2
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• pp.251-258
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• 2012

This study was conducted to analyze field inspection results of erosion control facilities within national forests and to suggest maintenance and management plan of erosion control facilities. The objects amounted to a total of 1,628 locations, comprising 308 erosion control dams and 1,320 erosion control areas (1,269.05 ha). The field inspections were conducted during March-June each year. The erosion control dams inspected were constructed during 1991-2005, with 96.4% of them, or 297 dams, constructed in or after 2000. The erosion control areas were constructed during 1986-2005, with 68.6% of them, or 903 areas, constructed in or after 2000. As for erosion control dams, there were 205 concrete erosion control dams and 68 concrete with boulder pitching erosion control dams, respectively, with 296 out of a total of 308 erosion control dams in a good condition. As for erosion control areas, there were many erosion control structures using stone masonry works and gabions, with 1,245 out of a total of 1,320 (94.3%) erosion control areas in a good condition. Overall, erosion control facilities within national forests were in a good condition, amply fulfilling their functions. As for erosion control facilities in a bad condition, they must be made to accomplish the goals of erosion control works through supplementation and repairs without fail. In addition, for the systematic maintenance and management of existing erosion control facilities and erosion control facilities constructed in the future as part of erosion control works, the construction of an erosion control facility management system is urgently needed.

• Journal of Korean Association for Spatial Structures
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• v.12 no.4
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• pp.99-108
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• 2012

In recently, sky-bridge are often applied to high-rised adjacent buildings for pedestrian bridge. the seisnic response control of adjacent buildings have been studied and magneto-rheological(MR) fluid dampers have been applied to seismic response control. In this study, vibration control effect of the MR damper connected adjacent buildings has been investigated. Adjacent building structures with different natural frequencies were used as example structures. Two typed of control methods, displacement based or velocity based, are applied to determinate control force of MR damper. In this numerical analysis, it has been shown that displacement-based control algorithm is more effective than velocity-based control algorithm for seismic response control of adjacent buildings. And, when displacement-based control method is applied to control of adjacent buildings, the control of building occurred large displacement is more efficient in reducing the seismic response.

• Communications for Statistical Applications and Methods
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• v.26 no.2
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• pp.103-129
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• 2019

The main goal of a case-control study is to learn the association between various risk factors and a primary outcome (e.g., disease status). Particularly recently, it is also quite common to perform secondary analyses of the case-control data in order to understand certain associations between the risk factors of the primary outcome. It has been repeatedly documented with case-control data, association studies of the risk factors that ignore the case-control sampling scheme can produce highly biased estimates of the population effects. In this article, we review the issues of the naive secondary analyses that do not account for the biased sampling scheme, and also the various methods that have been proposed to account for the case-control ascertainment. We additionally compare the results of many of the discussed methods in an example examining the association of a particular genetic variant with smoking behavior, where the data were obtained from a lung cancer case-control study.

• Journal of Korean Association for Spatial Structures
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• v.13 no.3
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• pp.91-98
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• 2013

A multi-input single-output (MISO) semi-active control systems were studied by many researchers. For more improved vibration control performance, a structure requires more than one control device. In this paper, multi-input multi-output (MIMO) semi-active fuzzy controller has been proposed for vibration control of seismically excited small-scale buildings. The MIMO fuzzy controller was optimized by multi-objective genetic algorithm. For numerical simulation, five-story example building structure is used and two MR dampers are employed. For comparison purpose, a clipped-optimal control strategy based on acceleration feedback is employed for controlling MR dampers to reduce structural responses due to seismic loads. Numerical simulation results show that the MIMO fuzzy control algorithm can provide superior control performance to the clipped-optimal control algorithm.

• Korean Journal of Childcare and Education
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• v.16 no.3
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• pp.99-117
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• 2020

Objective: Studies have revealed that parenting is a crucial factor for children's effortful control and externalizing behaviors, however, less is known about the underlying mechanism that may be moderated by maternal depression. Therefore, the present study is aimed to testify the mediating effect of children's effortful control and moderating effect of maternal depression in the association between parenting(i.e. limit setting, overprotective/permissive parenting) and children's externalizing behaviors. Methods: Three hundred and one mothers with 4 to 6 years old children reported their parenting behaviors, depression, their children's effortful control and externalizing behaviors. Data were analyzed using SPSS and Process Macro. Results: Results showed that children's effortful control mediated the association between parenting and children's externalizing behaviors and maternal depression moderated the association between parenting behaviors and children's effortful control as well as between parenting behaviors and children's externalizing behaviors. The moderated mediation effects were stronger among mothers with lower levels of depression. Conclusion/Implications: These findings could contribute to a better understanding of how and when maternal limit setting and overprotective/permissive parenting impact children's externalizing behaviors. It is suggested that future efforts to provide the parenting intervention take a target specific approach (e.g. considering mother's depression symptom), on order to maximize the effectiveness of program to ultimately facilitate children's positive adjustment.

• Journal of the Korean housing association
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• v.14 no.3
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• pp.77-84
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• 2003

This study analyzes the necessity and situation of the improvement of housing quality control system for the consumer. we find several defeats of the Housing Quality Control System in Korea. Especially there is no any organization that manange the total housing quality control. So this study suggest the home warranty system should be established as soon as possible for protectings home-buyers and improving housing quality.