• The Journal of the Korea Contents Association
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• v.15 no.5
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• pp.464-474
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• 2015

Smart devices are playing an increasing important role in today's knowledge society. On the other hand, its adverse effects are creating social problems as well. Thus, users have diverse attitude toward smart devices. In this regard, this study is aimed at examining the impact of attitudinal ambivalence and positive mind for the smart technology on consumer satisfaction. In order to achieve the research objective, we formulated research hypotheses. Then we conducted a questionnaire survey using college students to test hypotheses, and analyzed collected data using regression analysis. The results of our analysis indicated two key findings. First, it was found that attitudinal ambivalence had a negative effect on consumer satisfaction. Second, positive mind was found to have a positive effect on consumer satisfaction. Our findings are expected to make an academic contribution by enhancing our understanding of what leads to consumer satisfaction with smart devices.

• Archives of design research
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• v.17 no.3
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• pp.441-448
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• 2004

Mobile devices such as mobile phones or PDAs are considered as main interlace tools in ubiquitous computing environment. For searching information in mobile device, it should be possible for user to input some text as well as to control cursor for navigation. So, we should find efficient interlace method for text input in limited dimension of mobile devices. This study intends to suggest a new approach to mobile interaction using camera based virtual keyboard for text input in mobile devices. We developed a camera based virtual keyboard prototype using a PC camera and a small size LCD display. User can move the prototype in the air to control the cursor over keyboard layout in screen and input text by pressing a button. The new interaction method in this study is evaluated as competitive compared to mobile phone keypad in left input efficiency. And the new method can be operated by one hand and make it possible to design smaller device by eliminating keyboard part. The new interaction method can be applied to text input method for mobile devices requiring especially small dimension. And this method can be modified to selection and navigation method for wireless internet contents on small screen devices.

• The Journal of the Korea Contents Association
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• v.21 no.2
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• pp.707-717
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• 2021

The purpose of this study was to explore whether PPAT drawing using an application can be developed on digital devices for game addicts. The PPAT drawing test is useful and reliable for verifying problem-solving skills in how people pick apples. As a result of this study, the over-immersion group scored lower than the average user group in the "problem Solving" category of the PPAT drawing test using the PPAT drawing applicaion on digital devices, and expressed by not reaching for apples, or by picking apples without reasonable support. The findings in this study suggest that the PPAT drawing test application on digital devices has significantly demonstrated its original purpose of 'problem resolution', as well as future psychotherapeutic interventions for Internet over-immersion subjects as well as users who are familiar with digital devices.

• Journal of the Korea Convergence Society
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• v.12 no.2
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• pp.21-28
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• 2021

In this study, we propose a deep learning-based NILM technique using actual measured power data for 5 kinds of home appliances and verify its effectiveness. For about 3 weeks, the active power of the central power measuring device and five kinds of home appliances (refrigerator, induction, TV, washing machine, air cleaner) was individually measured. The preprocessing method of the measured data was introduced, and characteristics of each household appliance were analyzed through spectogram analysis. The characteristics of each household appliance are organized into a learning data set. All the power data measured by the central power measuring device and 5 kinds of home appliances were time-series mapping, and training was performed using a LSTM neural network, which is excellent for time series data prediction. An algorithm that can disaggregate five types of energies using only the power data of the main central power measuring device is proposed.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.6
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• pp.589-593
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• 2008

These days, as a side effect of the growth of the mobile devices, malwares for the mobile devices also tend to increase and become more dangerous. Because embedded Linux is one of the advanced OSes on mobile devices, a solution to preventing malwares from infecting and destroying embedded Linux will be needed. We present a scheme using signature verification for embedded Linux that prevents executallle-Infecting malwares. The proposed scheme works under collaboration between mobile devices and a server. Malware detection is delegated to the server. In a mobile device, only integrity of all executables and dynamic libraries is checked at kernel level every time by kernel modules using LSM hooks just prior to loading of executables and dynamic libraries. All procedures in the mobile devices are performed only at kernel level. In experiments with a mobile embedded device, we confirmed that the scheme is able to prevent all executable-Infecting malwares while minimizing damage caused by execution of malwares or infected files, power consumption and performance overheads caused by malware check routines.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.2
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• pp.105-111
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• 2009

The powers used in the motor drive system are mostly DC sources like batteries. Even AC powers in some systems are generated from DC sources by the inverter. It is can be forecasted that the DC-link communications will be widely used in various industrial fields. In this paper a novel BLDC motor drive system using DC-link communications is proposed. The characteristic of this system Is that the communication only needs 2 DC lines. There are not additional lines to translate the reference signals. And the reliability o3 the system is ensured especially under some terrible circumstances. The number of lines can be minimized when the DC-link communication method is applied in the multi motor control system and the slip ring design also can be simplified when this method is applied in rotation machines. The proposed motor system is clarified by the PSIM and MATLAB simulations and tested through the hardware prototype.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4270-4284
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• 2013

This study is research of actual proof on verification of the user's utility about mobile convergence products and the types of convergence categorize into four types according to their characteristics. Four types of convergence; (1)Open service via scalable internet, (2)Close service dependent on mobile phones, (3)Broadcast services such as DMB, (4)Individual products such as camera based on digital technology. The purpose of research model is to identify differences in effect value of the types of mobile convergence according to its usage level and level of quality. As the result of this study, Usage level of open service/individual products had a significant effect on the user's utility about mobile convergence products, Also Level of quality of open service had a significant effect.

• The Journal of the Acoustical Society of Korea
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• v.40 no.6
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• pp.607-614
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• 2021

Research on elevator noise has mainly focused on the cause of its occurrence and measures to reduce it. There is still insufficient research on how to accurately measure and evaluate elevator noise. There is a measurement method established as an international standard for the measurement method, but it is also difficult to apply to high-rise apartments, and there are many cases that do not closely reflect the characteristics of elevator noise. In order to solve this problem, a study was conducted to improve the elevator noise measurement method in the current standard. In this study, the characteristics of elevator noise were closely identified. Through frequency analysis of the elevator noise and other equipment, it was verified that the elevator noise is noise with different characteristics from other equipment. Elevator noise was compared with heavy floor impact noise, which is a representative structural transmission noise, as structural transmission noise. Elevator noise was compared with heavy floor impact noise, which is a representative structural transmission noise, as structural transmission noise. The correlation between bang machine and rubber ball was found to be very high at 0.9 level. As a result, it was verified that the mid-low frequency band of the elevator noise is the main structural transmission noise and cannot be evaluated together with other equipment.

• Journal of Digital Policy
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• v.1 no.2
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• pp.61-69
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• 2022

The paper is a study to develop and verify a blood glucose level prediction model based on biosignals obtained from photoplethysmography (PPG) sensors, ICT technology and data. Blood glucose prediction used the MLP architecture of machine learning. The input layer of the machine learning model consists of 10 input nodes and 5 hidden layers: heart rate, heart rate variability, age, gender, VLF, LF, HF, SDNN, RMSSD, and PNN50. The results of the predictive model are MSE=0.0724, MAE=1.1022 and RMSE=1.0285, and the coefficient of determination (R²) is 0.9985. A blood glucose prediction model using bio-signal data collected from digital devices and machine learning was established and verified. If research to standardize and increase accuracy of machine learning datasets for various digital devices continues, it could be an alternative method for individual blood glucose management.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.407-407
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• 2021

토양수분량은 그 양은 작지만 다양한 수문현상에 관여하는 주요한 수문인자 중 하나이다. 특히, 강우, 유출, 홍수 및 가뭄 등과 직접적인 연관이 있어 국내에서도 그 중요성이 점차 강조되고 있다. 일찍이 해외에서는 토양수분량 위성자료나 관측기기의 검증 및 교정을 위해 다수의 지상 관측소를 운영해왔으며, ISMN(International Soil Moisture Network)과 같은 기관을 통해 자료의 취합 및 품질관리, 배포 등도 활발하게 이루어지고 있다. 최근 국내에서도 최신 관측기기의 도입이나 수자원위성의 개발 등 토양수분량에 관한 연구가 점차 활발하게 이루어지고 있으며, 위성자료와 관측기기의 검증 및 교정을 위한 지상관측소도 점차 확대되고 있는 추세이다. 하지만, 국내 지상관측소는 현재 다양한 기관과 단체에 의해 운영되고 있으며, 품질관리 기준이 통일되어 있지 않아 자료의 접근 및 활용 측면에서 개선이 필요한 실정이다. 이에 한국수자원조사기술원은 국내 환경에 맞는 품질관리 기준을 제시하고, 자료의 접근성 및 활용성 개선의 토대를 마련하고자 품질관리 시스템을 개발하고 있다. 본 연구는 정량화된 품질관리 기준을 바탕으로 spike를 판별하는 알고리즘에 대한 성능평가를 다루고 있으며, 청미천 토양수분량 관측소 2020년 자료에 임의의 튀는 값(spike)을 추가하고, 해당 이상치의 검출여부를 확인하는 방식으로 진행되었다. 각각의 지점자료에서 강우사상 중 하강부, 무강우기간 중 하강부를 1개씩 선정하고, 해당 구간에 positive spike를 추가한 case와 negative spike를 추가한 case를 생성해 강우조건 및 spike 유형에 따른 검출성능 차이를 평가했다. 평가 결과, 강우기간 검출률 84.3%, 무강우기간 검출률 96.3%로 강우조건에 따른 성능차이가 명확하게 나타났으며, positive spike는 91.7%, negative spike는 88.9%로 spike 유형에 따른 검출성능차이는 미미했다. 강우조건과 spike 유형을 동시에 고려했을 때는 무강우기간의 positive spike가 98.2%로 가장 높은 검출률을 보인 반면에 강우기간의 negative spike는 83.3%로 가장 낮은 검출률을 보였다. 알고리즘이 검사시간대를 중심으로 24시간 동안의 토양수분량 변화를 감지하기 때문에 강우기간에 검출성능이 저하되는 것으로 판단되며, 이를 개선하기 위해선 강우사상에 따른 유동적인 window size 조절 알고리즘의 추가가 필요할 것으로 판단된다.