• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.3
• /
• pp.1570-1594
• /
• 2017

Social network services have recently changed from environments for simply building connections among users to open platforms for generating and sharing various forms of information. Existing user reputation computation methods are inadequate for determining the trust in users on social media where explicit ratings are rare, because they determine the trust in users based on user profile, explicit relations, and explicit ratings. To solve this limitation of previous research, we propose a user reputation computation method suitable for the social media environment by incorporating implicit as well as explicit ratings. Reliable user reputation is estimated by identifying malicious information raters, modifying explicit ratings, and applying them to user reputation scores. The proposed method incorporates implicit ratings into user reputation estimation by differentiating positive and negative implicit ratings. Moreover, the method generates user reputation scores for individual categories to determine a given user's expertise, and incorporates the number of users who participated in rating to determine a given user's influence. This allows reputation scores to be generated also for users who have received no explicit ratings, and, thereby, is more suitable for social media. In addition, based on the user reputation scores, malicious information providers can be identified.

• Journal of Environmental Health Sciences
• /
• v.37 no.1
• /
• pp.12-21
• /
• 2011

The objective of this study is to review retrospective exposure assessment methods used in wafer fabrication operations to determine whether adverse health effects including mortality or cancer incidence are related to employment in particular work activities and to recommend an appropriate approach for retrospective exposure assessment methods for epidemiological study. The goal of retrospective exposure assessment for such studies is to assign each study subject to a workgroup in such a way that differences in exposure within the workgroups are minimized, as well as to maximize the contrasts in exposure between workgroups. To reduce the misclassification of exposure and to determine if adverse health effects including mortality or cancer incidence are related to particular work activities of wafer fabrication workers, a minimum requirement of work history information on the wafer manufacturing eras, job and department at which they were exposed should be assessed. Retrospective assessment of the task that semiconductor workers performed should be conducted to determine not only the effect of a particular job on the development of adverse health effects including mortality or cancer incidence, but also to adjust for the healthy worker effect. In order to identify specific hazardous agents that may cause adverse health effects, past exposure to a specific agent or agent matrices should also be assessed.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.7 s.112
• /
• pp.690-696
• /
• 2006

Thickness of damping layer in sandwich plate needs to be optimized in order to make modal loss factor of the sandwich plate maximum. Since previous studies were interested in noise reductions over high frequency range, the modal properties were derived based on simply supported boundaries. This conventional formula is approximately applicable to other boundary conditions over high frequency range only. The purpose of this study is to propose a method to determine optimum damping layer thickness of sandwich plate for maximum modal damping in low frequency range when the boundary condition is not a simple support. The conventional RKU equation based on simply supported boundary is modified to reflect other boundary conditions and the modified RKU equation is subsequently applied to determine the optimum damping layer thickness for arbitrary conditions. In order to reflect frequency-dependent characteristics of elastic modulus of the damping layer, an iteration method is proposed in determining the modal properties. Test results on sandwich plates for optimum damping layer thickness are compared with predictions by the proposed method and conventional method.

• Journal of Korea Society of Industrial Information Systems
• /
• v.13 no.4
• /
• pp.14-23
• /
• 2008

Information Technology (IT) managers play an important role as a bridge between technology and business, and it is therefore important to determine what skills are required for this position. Although many previous studies have investigated the skills necessary for IT managers to perform their roles, most of these studies are based on the data collected from companies in the US. However, given the increased labor mobility in the IT industry, it is important to determine whether IT manager positions elsewhere require the same skills as the positions in the US. This study is a first step in this direction and attempts to determine whether there are any differences in skill requirements between Korean IT managers and American IT managers, and, if so, what they are.

• Earthquakes and Structures
• /
• v.18 no.5
• /
• pp.543-553
• /
• 2020

Past earthquakes experience shows that serious damage or collapse of buildings have dramatically accrued when sufficient separation distance has not been provided between two adjacent structures. The majority of past studies related to the pounding topic indicate that obtaining the gap size between two buildings is able to prevent collision and impact hazards during seismic excitations. Considering minimization of building collisions, some relationships have been suggested to determine the separation distance between adjacent buildings. Commonly, peak lateral displacement, fundamental period and natural damping as well as structural height of two adjacent buildings are numerically considered to determine the critical distance. Hence, the aim of present study is to focus on all mentioned parameters and also utilizing the main characteristic of earthquake record i.e. PGA to examine the lateral displacement of irregular structures close to each other and also estimate the sufficient separation distance between them. Increasing and decreasing the separation distance is inherently caused economical problems due to the land ownership from a legal perspective and pounding hazard as well. Therefore, a new equation is proposed to determine the optimum critical distance. The accuracy of the proposed formula is validated by different models and various earthquake records.

• Journal of dental hygiene science
• /
• v.17 no.3
• /
• pp.218-225
• /
• 2017

The purpose of this study was to determine the association between drinking behaviors and the need for periodontal treatment. The data of 5,995 adults from the 2012 Korea National Health and Nutrition Examination Survey were categorized into young adulthood (19~39 years), middle age (40~64 years), and old age (${\geq}65$ years) and analyzed. Chi-square test was performed to determine those who needed periodontal treatment by the respondents' general characteristics and drinking behaviors, and logistic regression analysis was carried out to determine the impact of each drinking behavior on the need for periodontal treatment. The results of this study have confirmed that alcohol intake is a factor adversely affecting periodontal status; therefore, patients should know the fact that excessive alcohol intake and increased frequency of drinking may affect the prevalence rate of periodontal diseases. Moreover, moderate-drinking programs that can reinforce prevention of drinking so that dental hygienists can provide good oral health care should be developed. A systematic oral health promotion program should be introduced for constant prevention with the objective of activating oral health education that focused on middle-aged and young-adult people in pursuit of healthy aging society.

• Proceedings of the Ginseng society Conference
• /
• 1987.06a
• /
• pp.38-46
• /
• 1987

The present study was undertaken to determine the inhibitory effects of orally administered ginseng saponins (GS), protopanaxadiol saponins(PD) and protopanaxatriol saponins(PT) on the development of morphine induced tolerance and physical dependence in mice, and to determine the increases in the loss of morphine tolerance and dependence. The study also sought to determine the hepatic glutathione contents, which are closely related to the degree of detoxication of morphinone, a novel metabolite of morphine, and the effects of ginseng saponins on morphine 6-dehydrogenase. The results of the present study showed that GS, PD and PT administered orally inhibited the development of morphine-induced tolerance and dependence. GS, PD and PT, however, increased the loss of morphine tolerance and dependence. GS, PD and PT inhibited the reduction of hepatic glutathione concentration in mice treated chronically with morphine, and the activity of morphine 6-dehydrogenase. So we hypothesized that these results were partially due to the dual action of the test drugs, the inhibition of morphine production and the activation in morphine-glutathione conjugation due to the increased glutathione level for detoxication.

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.8
• /
• pp.815-823
• /
• 2013

The hot curvature forming of large aluminum plates is a process used to produce spherical liquefied natural gas (LNG) tanks. In this study, we describe a method to determine the optimum shape of blanks to minimize the root gap in the forming process. The method proposed in this study was applied to a small-scale model for thick plates with a curvature of 1500 mm and thickness of 6 mm. First, the shape of the curved shells was determined as the target shape, and then a coordinate transform was used to determine the optimum blank shape, which was then iteratively modified using the results of finite element method (FEM) simulations, including heat transfer, until the shape error was minimized. Experiments in forming using Al5083 thick plate were carried out, showing that the method can determine the optimum blank shape within an allowable root gap of 0.1 mm.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.9
• /
• pp.202-209
• /
• 2000

In recent years the concern of designing multi-stage gear drives increases with the more application of gear drives in high-speed and high-load. until now however research on the gear drive design has been focused on single gear pairs and the design has been depended on experiences and know-how of designers and carried out commonly by trial and error. We propose the automation of the dimensional design of gears and the configuration design for gear arrangement of two-and three-stage cylindrical gear drives. The dimensional design is divided into two types of design processes to determine the dimensions of gears. The first design process(Process I) uses the total volume of gears to determine gear ratio and uses K factor unit load and aspect ratio to determine gear dimensions. The second one(Process II) makes use of Niemann's formula and center distance to calculate gear ratio and dimensions. Process I and II employ material data from AGMA and ISO standards respectively. The configuration design determines the positions of gears to minimize the volume of gearbox by simulated annealing algorithm. Finally the availability of the design algorithm is validated by the design examples of two-and three-stage gear drives.

• Journal of Arbitration Studies
• /
• v.25 no.1
• /
• pp.65-86
• /
• 2015

Under current international investment law clear criteria to determine standards of indirect expropriation are absent. Arbitral tribunals determine on a case-by-case whether an indirect expropriation has occurred by conducting a fact-based inquiry. However, three common determination standards can be inferred by analyzing prior arbitration cases. The appropriate analytical framework that can be applied to determine whether a state's measure constitutes an indirect expropriation is as follows. i) the degree of economic invasion of the state's action into the foreign investor's property rights and durability of the period, ii) interference with the foreign investor's distinct and reasonable investment-backed expectations, and iii) the nature, purpose and character of the state's measure. Therefore, it is necessary to fully acknowledge and to utilize strategically this determination standard. However, derived standards cannot be applied to all disputes en masse. So, it is desirable to exclude ambiguity and to clearly define the determination standard of indirect expropriation in investment agreements, since arbitral tribunals can apply different determination standards on a case-by-case basis. And, based on the discussions until now, more developed standards and direction in response to demand should be established through consistent analysis and review of precedents related to indirect expropriation. Lastly, This study is expected to be a useful guideline to prepare a necessary countermeasure to prevent dispute related to indirect expropriation beforehand or in case of dispute occurrence.