• Journal of Digital Convergence
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• v.15 no.11
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• pp.107-112
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• 2017

This paper performed an experimental study to test the validity of the prospect theory proposed by Tversky and Kahneman as an alternative to the expected utility theory. 115 college students attended the hypothetical games to choose one of two lotteries, one is safe option while the other one is risky. The risky options were set up to have low, medium or high probability of payoffs or losses. The amount of payoffs and losses of the lotteries was either large or small. Maximum likelihood estimation of the hypothetical games have shown that in case of high probability of positive payoffs the respondents were risk averse and when the probability of positive payoffs were small the respondents were risk loving. when the possibility of loss is high they were risk loving, while the probability is of loss is low the respondents were found to be risk averse. When the probability of risky options were medium the results were significant statistically in case of only losses. The amount of positive payoff or losses does not affect the results. Overall the results of this experiments support the prospect theory more than those of Laury & Holts (2008).

• Journal of Korean Dental Hygiene Science
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• v.4 no.1
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• pp.11-18
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• 2021

Background: The present study aimed to analyze which curriculum is the most relevant to dental hygiene students when they participate in clinical practice in order to provide a useful reference for preparing educational guidance in this field. Method: The survey utilized in the present study consisted of six questions about general characteristics, such as grade, satisfaction with major, amount of clinical practice, period of clinical practice, place of clinical practice, and the most interesting are during clinical practice. When evaluating curriculum relevancy, the following were ranked on a 5-point Likert scale, where 5 = very useful, 4 = comparatively useful, 3 = normal, 2 = comparatively unuseful, 1 = very unuseful: difference in requirements in the field of clinical practice, reason for this difference, and question about the utility of each curriculum. On this scale, higher points implied higher relevance. Result: The highest groups of curricula regarding curriculum utility were as follows: operative dentistry (59.6%), pre-clinical practice (55.2%), dental materials and clinical practice (54.4%), and prosthetic dentistry (49.6%). The lowest groups of curricula regarding curriculum utility were as follows: oral physiology (2.0%), oral histology and embryology (1.6%), and oral microbiology (1.2%). These results imply a lack of connection between the curriculum and tasks in clinical practice. Conclusion: Based on the results of the present study, it appears that both theory and practice courses of the clinical curriculum must be conducted systematically, and that there is a need to conduct education for the fundamental curricula, such as oral physiology, oral histology and embryology, and oral microbiology, regarding the relevance of tasks practiced in clinics.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.4
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• pp.1493-1515
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• 2015

A smart meter is one of the core components in Advanced Metering Infrastructure (AMI) that is responsible for providing effective control and monitor of electrical energy consumptions. The multifunction tasks that a smart meter carries out such as facilitating two-way communication between utility providers and consumers, managing metering data, delivering anomalies reports, analyzing fault and power quality, simply show that there are huge amount of data exchange in smart metering networks (SMNs). These data are prone to security threats due to high dependability of SMNs on Internet-based communication, which is highly insecure. Therefore, there is a need to identify all possible security threats over this network and propose suitable countermeasures for securing the communication between smart meters and utility provider office. This paper studies the architecture of the smart grid communication networks, focuses on smart metering networks and discusses how such networks can be vulnerable to security attacks. This paper also presents current mechanisms that have been used to secure the smart metering networks from specific type of attacks in SMNs. Moreover, we highlight several open issues related to the security and privacy of SMNs which we anticipate could serve as baseline for future research directions.

• Journal of Digital Convergence
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• v.16 no.10
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• pp.445-452
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• 2018

In a world where everything in life is being digitized, the amount of data is increasing exponentially. These data are processed into new data through collection and analysis. New data is used for a variety of purposes in hospitals, finance, and businesses. However, since existing data contains sensitive information of individuals, there is a fear of personal privacy exposure during collection and analysis. As a solution, there is privacy-preserving data mining (PPDM) technology. PPDM is a method of extracting useful information from data while preserving privacy. In this paper, we investigate PPDM and analyze various measures for evaluating the privacy and utility of data.

• Journal of ILASS-Korea
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• v.27 no.2
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• pp.94-100
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• 2022

Even in non-road UTV (Utility Terrain Vehicle), spark ignition engines are often used to reduce emissions. In this study, gasoline and LPG (Liquified Petroleum Gas) fuels were applied to UTV engines, and the exhaust gas and combustion stability were compared through engine tests. A 0.8-liter two-cylinder SI engine was used in the experiment. Experiments were conducted while changing the IVO (Intake Valve Open) and EVC (Exhaust Valve Close) at 1500 rpm 14 N·m, 40 N·m, and 3000 rpm 17 N·m, 44 N·m conditions. As a result of the experiment, when the valve overlap increased according to the change of IVO and EVC, combustion stability decreased and THC emission increased, but NOx decreased. Comparing the LPG engine with the gasoline engine, the amount of CO₂ and PN (Particulate Number) generation decreased in the LPG engine, and the combustion stability was good.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.8
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• pp.707-712
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• 2014

Aircraft fuel indicator is a device to indicate the amount of fuel remained during flight, where accurate and consistent operation of the indicator should be maintained. Previously the Korean Utility Helicopter fuel indicator sporadically displayed abnormal sign by "8888" during flight, jeopardizing flight safety. Inappropriate EMI/EMC performance was detected during trouble shooting process. The cause of the abnormal display was found to be resulted from unstable power induced by electro-magnetic disturbance and CAN communication error. The aircraft fuel indicator design was improved and the design compatibility was verified to avoid abnormal display.

• The KIPS Transactions:PartA
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• v.13A no.4 s.101
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• pp.363-370
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• 2006

Currently, many people have been researching diverse mechansmims related to a resource access control in Grid environment. Mostly Grid user's resource access control was designed to authorize according to their attributes and roles. But, to provide Grid with resources continuously, a resource access based on utility computing must be controlled. So, in this paper we propose and implement mechanism that intergrates Grid accounting concept with resource access control. This mechanism calcuates costs of Grid service on the basis of accounting, and determines based on user's fund availibility whether they continue to make use of site resources or not. Grid jobs will be controlled according to a site resource access control policy only if the amount of available fund is less than its costs. If Grid job completed, resource consumer pays for the costs generated by using provider's idle resources. Therefore, this paper provides mechansim to be able to control user's resource access by Grid accounting, so that it is evaluated as the research to realize utility computing environment corresponding to economic principle.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.11
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• pp.5264-5281
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• 2017

Multihop relay-based cellular networks are attracting much interest because of their throughput enhancement, coverage extension, and low infrastructure cost. In these networks, relay stations (RSs) between a base station (BS) and mobile stations (MSs) drastically increase the overall spectral efficiency, with improved channel quality for MSs located at the cell edge or in shadow areas, and enhanced throughput of MSs in hot spots. These relay-based networks require an advanced radio resource management scheme because the optimal amount of radio resource for a BS-to-RS link should be allocated according to the MS channel quality and distribution, considering the interference among RSs and neighbor BSs. In this paper, we propose optimal resource planning algorithms that maximize the overall utility of relay-based networks under a proportional fair scheduling policy. In the first phase, we determine an optimal scheduling policy for distributing BS-to-RS link resources to RSs. In the second phase, we determine the optimal amount of the BS-to-RS link resources using the results of the first phase. The proposed algorithms efficiently calculate the optimal amount of resource without exhaustive searches, and their accuracy is verified by comparison with simulation results, in which the algorithms show a perfect match with simulations.

• Journal of Biomedical Engineering Research
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• v.35 no.5
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• pp.125-131
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• 2014

The purpose of this study is to verify the utility of reflected photoplethysmography sensor using two green light emitting diodes that influenced by ambient light. Recently it has been studied that green light emitting diode is suitable for light source of reflected photoplethysmography sensor at low temperature and high temperature. Another study showed that, green light is better for monitoring heart rate during motion than led light. However, it has a bad characteristic about ambient light noise. To verify the utility of reflected photoplethysmography sensor using green light emitting diode, this study measures the photoplethysmography signal that is distorted by ambient light and will propose a solution. This study has two parts of research method. One is measurement system that composed sensor and board. The sensor is made up PE-foam and Non-woven fabric for flexible sensor. The photoplethysmography signal is measured by measurement board that composed high-pass filter, low-pass filter and amplifier. Ambient light source is light bulb and white light emitting diode that has three steps brightness. Photoplethysmography signal is measured with lead II electrocardiography signal at the same time and it is measured at the finger and radial artery for 1 minute, 1000 Hz sampling rate. The lead II electrocardiography signal is a standard signal for heart rate and photoplethysmography signal that measured at the finger is a standard signal for waveform. The test is repeated 3 times using three sensor. The data is processed by MATLAB to verify the utility by comparing the correlation coefficient score and heart rate. The photoplethysmography sensor using two green light emitting diodes is shown better utility than using one green light emitting diode and red light emitting diode at the ambient light. The waveform and heart rate that measured by two green light emitting diodes are more identical than others. The amount of electricity used is less than red light emitting diode and error peak detectability factor is the lowest.

• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.1
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• pp.161-167
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• 2001

The purpose of this study is to find out the difference of Zoysia matrella's evaporation in between 100 percent soil and mixed soil with 50 percent of perlite to create green spaces on the artificial ground. It is believed that the weight against the artificial ground will be reduced, provided the vegetation is possible in the circumstance of the mixed sol with 50 percent of perlite. The study employed a modified Makkink's model by Iwasa who had developed the model for estimating Zoysia matrella's evaporation in the natural ground using the Makkink's formula in 1997 at Chiba University, Japan. The parameter of Makkink's formula is the solar radiation. For that reason, the Makkink's formula is simple and easy to measure the parameter and has a high utility. If the outcomes from mixed soil are close to modified Makkinks formula, the modified Makkink's formula will be applied to estimate in the artificial ground with mixed soil with 50 percent of perlite. Weather observation and actual amount of evaporation of Zoysia matrella have been measured, and the relation between weather condition and actual amount of evaporation had been also investigated. In line with this, we found out that there is a relevant relationship between daily average temperature, the modified Makkink's model by Iwasa, and the actual amount of evaporation. As the results of the experiment, the outcomes from mixed soil with 50 percent of perlite have very high relation to 100 percent soil. In addition, mixed soil has more adhesion with water than natural soil. However, it needs to be adequately maintained in terms of fertilization and damage from disease and harmful insects until the gras fastens its roots into the soil. By using mixed soil with 50 percent of perlite, the load from soil on the artificial ground can be reduced. The study on the growth of the grass throughout the plant vegetation and the actual amount of evaporation in the mixed soil with 50 percent of perlite should be performed in the future.