• Safety and Health at Work
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• v.15 no.1
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• pp.73-79
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• 2024

Background: This study aimed to investigate the relationship between work-related communication devices use during work outside of regular working hours and depressive symptoms in wage workers. Methods: Data from 50,538 workers aged 15 years or older who had participated in the 6th Korean Working Condition Survey (KWCS) were used. The final sample was 32,994 wage workers. The questionnaire asked the respondents how often they used communication devices for work during work outside of regular working hours. Depressive symptoms were assessed using WHO-5 Well-Being Index. Multiple logistic regression analysis was used to analyze the association between work-related communication devices use during work outside of regular working hours and depressive symptoms. Results: The rate of depressive symptoms was highest among workers who did not use work-related communication devices during work outside of regular working hours. After adjusting for socio-demographic and work-related factors, the odds ratio of depressive symptoms among workers who used communication devices when working outside of regular working hours was 1.20 (95% CI: 1.09-1.32); the odds ratio of depressive symptoms in the group not using communication devices for free-time work was 1.66 (95% CI: 1.37-2.00), which was higher than that of the reference group, that is, workers who did not work outside of regular working hours, and was statistically significant. Conclusion: Regardless of whether work-related communication devices are used, working outside of regular working hours increases depressive symptoms. The use of work-related communication devices during work outside of regular working hours can reduce the rate of depressive symptoms.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.988-991
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• 2004

In the present investigation, we tried AR coating simulation by using the "Essential Macleod optical coating design and analysis" program. After various run of the program we selected appropriate materials which have specific refractive indices and for that thickness was optimized to get the low reflectance. By comparing the simulated results for the different materials,we found that $SiO_2$ and TiN are the appropriate materials for this Flat panel device (FPD) application. Thin films of these materials were deposited using RF magnetron sputtering and Inductively Coupled Plasma Chemical Vapour Deposition (ICPCVD) methods on Polyethyleneterephthalate (PET) substrates. Spectroscopic ellipsometer (SE MF-1000) and UV-Vis spectrophotometer (SCINCO) were used for the optical characterization. The obtained experimental results are in good agreement with the simulation results.

• ETRI Journal
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• v.25 no.2
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• pp.81-88
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• 2003

We designed a multimode interference (MMI) coupler to use in vertical coupling of double layered polymeric waveguides and analyzed the coupling characteristics by comparing our experimental and simulation results. We found that our proposed new structure, a stepped MMI coupler, is effective in vertical coupling between waveguide layers with a short length of MMI and has a high tolerance for the variation in the structure of an MMI coupler that can be induced as errors in the fabrication process.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1054-1057
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• 2002

The design and fabrication of Q-band 3-stage monolithic microwave integrated circuit(MMIC) amplifier for WLAN are presented using 0.2$\square$ AIGaAs/lnGaAs/GaAs pseudomorphic high electron mobility transistor (PHEMT). In each stage of the MMIC, a negative feedback is used for both broadband and good stability. The measurement results are achieved as an input return loss under -4dB, an output return loss under -10dB, a gain of 14dB, and a PldB of 17dBm at Q-band(36～44GHz). These results closely match with design results. The chip size is 2.8${\times}$1.3mm$^2$. This MMIC amplifier will be used as the unit cell to develop millimeter-wave transmitters for use in wideband wireless LAN systems.

• International Journal of Internet, Broadcasting and Communication
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• v.5 no.1
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• pp.18-22
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• 2013

We introduce, in this paper, a novel approach of protection mechanism for data which are transmitted not only between the networked devices but also between the digital media devices. As the devices are getting more powerful and more storage capacity, they can process the encoded/encrypted data autonomously. However, all devices must know the secret key that used to encrypt data, and also use secure method to distribute that key. Moreover, there are no protection mechanisms supporting end-to-end copy protection which result in the fact that the data passed through various devices can be manipulated or captured. Therefore, we propose a RFID-based key distribution and protection mechanism to resolve these problems.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.4
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• pp.11-23
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• 2015

In this paper, we propose a communication middleware for development of HACCP(Hazard Analysis and Critical Control Point) automation system, which is composed of lightweight devices and a server, to support effective HACCP data management. To provide the proper HACCP data to lightweight devices, we design the communication message protocol based on HACCP management regulation model. Moreover, we develop the communication middleware that performs various functions, such as processing of communication protocols for HACCP data, analyzing of messages between devices and a server, and providing database managements tools. In addition, it takes a role to guarantee sharing consistent data among the devices and server, through the active updates for information on devices. Actually, the proposed communication middleware can be a part of critical system to develop a HACCP automation system with lightweight devices, because it implements the HACCP communication protocols making lightweight devices execute every HACCP task.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.4662-4677
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• 2018

The dynamic opportunistic device-to-device (DO-D2D) network will frequently emerge in the fifth generation (5G) wireless communication due to high-density and fast-moving mobile devices. In order to improve the Quality of Experience (QoE) of users with different computing capacity devices in the DO-D2D network, in this paper, we focus on the study of how to reduce the packets retransmission delay and satisfy heterogeneous devices. To select as many devices as possible to transmit simultaneously without interference, the concurrent transmitters-selecting algorithm is firstly put forward. It jointly considers the number of packets successfully received by each device and the device's connectivity. Then, to satisfy different devices' demands while primarily ensuring the base-layer packets successfully received by all the devices, the layer-cooperation instantly decodable network coding is presented, which is used to select transmission packets combination for each transmitter. Simulation results illustrate that there is an appreciable retransmission delay gain especially in the poor channel quality network compared to the traditional base-station (BS) retransmission algorithm. In addition, our proposed algorithms perform well to satisfy the different demands of users with heterogeneous devices.

• Human Ecology Research
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• v.57 no.4
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• pp.523-534
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• 2019

This study identifies correlations between the use of media devices, communication ability, and executive function difficulties for third grade students, as well as investigates the moderating effect of a child's communication ability. Data from the 10th (2017) Panel Study on Korean Children [PSKC] was employed (N=557). Descriptive statistics, Pearson's correlation and hierarchical regression were used along with SPSS 25.0(IBM Co., Armonk, NY, USA). The results were as follows. First, the executive function difficulties in the third-grade showed a significant positive correlation with media device use. While also, showing a negative correlation with a child's communication ability. Media devices use and communication ability has a significant negative correlation. Second, a child's communication ability has a moderating effect in relation to the use of media devices and executive function difficulties. The difficulty of executive function showed a reciprocal increase to a child's use of media devices and indicated a discriminatory effect of a child's communication ability. In conclusion, this study shows that communication ability is important as a personal factor for children who control the negative effects of media devices. Therefore, it is necessary to provide and support an environment for the development of a child's communication ability.

• Journal of Korea Society of Digital Industry and Information Management
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• v.14 no.3
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• pp.11-20
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• 2018

Smart devices refer to various devices and control equipment such as health care devices, imaging devices, motor devices and wearable devices that use wireless network communication (e.g., Wi-fi, Bluetooth, LTE). Commercial services using such devices are found in a wide range of fields, including home networks, health care and medical services, entertainment and toys. Studies on smart devices have also been actively undertaken by academia and industry alike, as the penetration rate of smartphones grew and the technological progress made with the fourth industrial revolution bring about great convenience for users. While services offered through smart devices come with convenience, there is also various security threats that can lead to financial loss or even a loss of life in the case of terrorist attacks. As attacks that are committed through smart devices tend to pick up where attacks based on wireless internet left off, more research is needed on related security topics. As such, this paper seeks to design an access control method for reinforced security for smart devices. After registering and authenticating the smart device from the user's smart phone and service provider, a safe communication protocol is designed. Then to secure the integrity and confidentiality of the communication data, a management process such as for device renewal or cancellation is designed. Safety and security of the existing systems against attacks are also evaluated. In doing so, an improved efficiency by approximately 44% compared to the encryption processing speed of the existing system was verified.

• Journal of information and communication convergence engineering
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• v.1 no.3
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• pp.129-132
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• 2003

In this paper, cobalt (Co)-electrode FBAR devices fabricated on seven-layered Bragg Reflectors are presented along with their resonance characteristics. ZnO films are used as the resonating material in FBAR devices where the Co electrode is 3000${\AA}$ thick. All processes are preformed in an RF magnetron sputtering system. As a result of characterization, the resonance characteristics are observed to depend strongly on the quality of ZnO film and Bragg Reflectors. In addition, the FBAR devices with W/$SiO_2$ reflectors show good resonance characteristics in term of return loss and quality-factor (Q-factor).