• 디지털융복합연구
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• 제15권11호
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• pp.107-112
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• 2017

이 논문은 전통적인 기대효용이론의 한계를 극복하기 위해 대안으로 제시된 Tversky와 Kahneman의 전망이론이 타당한지에 대해 실험연구를 통하여 검증하였다. 연구방법은 대학생 115명에게 가상적인 2개의 대안 중에서 하나를 선택하도록 하는 게임을 제시하였는데, 하나는 위험이 없는 안전한 투자안이며 다른 하나는 위험이 있는 투자안이다. 위험한 대안은 발생확률이 낮은 경우, 중간인 경우, 그리고 높은 경우로 구분하였으며, 게임의 금액도 이득이 발생하는 경우와 손실이 발생하는 경우로 나누었으며, 금액이 큰 경우와 작은 경우로 구분하여 실험을 하였다. 참가자들로부터 받은 응답을 최우추정법으로 분석한 결과, 이득의 상황에서 위험대안의 발생 가능성이 큰 경우에는 위험회피적, 위험대안의 발생 확률이 작은 때에는 위험선호적, 위험대안의 발생가능성이 작은 경우에는 위험회피적인 것으로, 그리고 위험대안의 발생확률이 중간인 경우에는 손실의 경우에만 통계적 유의성이 있었으며, 이득의 경우에는 유의적이지 않은 것으로 나타났다. 게임의 금액의 크기는 이득의 상황이건 손실의 경우이건 영향을 미치지 않았다. 따라서 본 연구의 결과는 Laury & Holt (2008)의 연구보다 대체로 더 강하게 전망이론을 지지하는 것으로 해석된다.

• 대한치위생과학회지
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• 제4권1호
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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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• 제9권4호
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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.

• 디지털융복합연구
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• 제16권10호
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• pp.445-452
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• 2018

생활의 모든 것들이 데이터화 되어가고 있는 세상에서 데이터의 양은 기하급수적으로 증가하고 있다. 이러한 데이터는 수집 및 분석을 통하여 새로운 데이터로 가공되어진다. 새로운 데이터는 병원, 금융, 기업 등 여러 분야에서 다양한 용도로 사용되고 있다. 그러나 기존의 데이터에는 개인들의 민감한 정보가 포함되어 있기 때문에 수집 및 분석과정에서 개인의 프라이버시 노출 우려가 있다. 해결 방안으로 프라이버시 보존형 데이터 마이닝(PPDM)기술이 있다. PPDM은 프라이버시를 보존하면서 동시에 데이터로부터 유용한 정보를 추출하는 방법이다. 본 논문에서는 PPDM을 조사하고 데이터의 프라이버시와 유틸리티를 평가하기 위한 다양한 측정방법을 분석한다.

• 한국분무공학회지
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• 제27권2호
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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.

• 한국항공우주학회지
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• 제42권8호
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• pp.707-712
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• 2014

항공기의 연료량 지시계는 비행동안 잔여 연료량을 시현해주는 장치로 비행 중에는 정상적으로 성능을 발휘해야 한다. 한국형 기동헬기 연료량 지시계는 비행 중에 결함코드 "8888"을 시현하여 잔여 연료량을 확인하지 못해 비행안전에 영향을 끼쳤으며 고장탐구과정에서 개발과정 시 미흡하게 설계된 EMI/EMC 성능을 확인하였다. 본 논문에서는 비행 중 결함코드를 시현하는 원인인 전자기 외란에 의한 전원 불안정 및 CAN 통신 오류를 확인하고 이와 연관된 연료시스템의 개선 및 설계 적합성을 입증하였다.

• 정보처리학회논문지A
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• 제13A권4호
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• pp.363-370
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• 2006

현재 그리드 환경에서 자원 접근 제어에 관련된 다양한 방법들이 연구되고 있다. 대부분 그리드 사용자의 자원 접근 권한은 사용자의 특성 및 역할에 따라 부여하도록 설계되었다. 그러나 그리드에 안정적인 자원을 지속적으로 제공하기 위해서는 유틸리티 컴퓨팅에 의한 자원 접근 제어가 이루어져야 한다. 따라서 본 논문에서는 자원 접근 제어에 그리드 어카운팅 개념을 접목시킨 메커니즘을 제안한다. 이 메커니즘은 자원 사용에 대한 어카운팅 정보를 기초로 처리 비용을 산출하고, 사용자의 가용 자금에 따라 자원 접근 여부를 결정하게 된다. 만약 사용자의 가용 자금이 자원 사용에 대한 처리 비용보다 부족할 경우, 사이트의 자원 접근 제어 정책에 따라 그리드 작업을 제어하게 된다. 최종적으로 그리드 작업이 완료되면, 자원 소비자가 자원 제공자측의 유휴 자원을 사용함으로써 발생되는 처리 비용을 지불한다. 그럼으로 본 논문은 그리드 어카운팅에 의한 사용자의 자원 접근을 제어할 수 있는 메카니즘을 제공함으로써, 경제 원리에 준하는 유틸리티 컴퓨팅 환경을 실현할 수 있는 연구로 평가된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권11호
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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.

• 대한의용생체공학회:의공학회지
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• 제35권5호
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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.

• 한국조경학회지
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• 제29권1호
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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.