• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.813-818
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• 2020

Recently, with the rapid increase in technology and users of smart devices, the smart watch market has grown, and its utility and usability are continuously expanding. The strengths of smartwatches are wearable portability, application immediacy, data diversity and real-time capability. Despite these strengths, smartwatches have limitations such as battery limitations, display and user interface size limitations, and memory limitations. In addition, there is a need to supplement developers and standard devices, operating system standard models, and killer application modules. In particular, monitoring and application of user's biometric information is becoming a major service for smart watches. The biometric information of such a smart watch generates a large amount of data in real time. In order to advance the biometric information service, stable peer-to-peer transmission of sensing data to a remote smartphone or local server storage must be performed. We propose a synchronization method to ensure wireless remote peer-to-peer transmission stability in a smart watch system. We design a wireless peer-to-peer transmission process based on this synchronization method, analyze asynchronous transmission process and proposed synchronous transmission process, and propose a transmission efficiency method according to an increase in transmission amount.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.1
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• pp.33-38
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• 2009

The use of portable devices has created the need for new reliability criterion of drop impact tests because of the tendency to accidentally drop in the use of these devices. The effects of different PCB surface finishes (organic solderability preservative (OSP) and electroless nickel immersion gold (ENIG)) and high temperature storage (HTS) test on the drop reliability were studied. Various drop test conditions were used to evaluate a drop reliability of assemblies to endure such impact and shock load. In the case of the as-reflowed samples (no HTS test), the SAC/OSP boards exhibited a better drop impact reliability than that of SAC/ENIG. However, the reverse was true if HTS test is performed. In addition, significant decrease of drop reliability was observed for both SAC/ENIG and SAC/OSP assemblies after HTS test. It was also observed that the thickness of intermetallic compound layer do play an important role in the brittle fracture of drop test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.1795-1801
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• 2009

In this study, a portable flashlight which can manually generate the electricity by using sunlight was developed so that it can be used in the extreme environmental condition such as no-electricity condition. Battery is charged by using solar battery during the day, but when sunlight is not avalible during the night or rainy day, a handle is rotated to generate the electricity in order to charge the battery manually. To improve the brightness of the light, light is concentrated by using the optical lens. Low electric consumption circuit is used for the longer operating time by suppress electrical consumption while lamp is discharged. A circuit is designed and used for steady electrical curris dand voltage to insure steady battery charging. Super-discharge circuit and protection circuit are used for the super discharge of battery when it is not used for a long time. Also the constant charge is possible by using houseware adapter. As a result, a portable flashlight is designed to charge with sunlight during day, and with houseware adapter during night. A portable flashlight is also designed to irradiate longer distances by improvement of the brightness of the light using the optical lens. Thus, it forms white natural ray of light making possible for night reading.

• The KIPS Transactions:PartD
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• v.12D no.5 s.101
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• pp.699-708
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• 2005

It becomes easy and generalized to track the cellular phone users and vehicles according to the Progress of wireless telecommunication, the spread of network, and the miniaturization of terminal devices. It has been constantly studied to provide location based services to furnish suitable services depending on the positions of customers. Various vehicle tracking and management systems are developed to utilize and manage the vehicle locations to relieve the congestion of traffic and to smooth transportation. However the designed previous work can not evaluated in real world, because most of previous work is only designed not implemented and it is developed for simple model to handle a point, a line, a polygon object. Therefore, we design a moving object query language and implement a vehicle management system to search the positions and trajectories of vehicles and to analyze the cost of transportation effectively. The designed query language based on a SQL can be utilized to get the trajectories between two specific places, the departure time, the arrival time of vehicles, and the predicted uncertainty positions, etc. In addition, the proposed moving object query language for managing transportation vehicles is useful to analyze the cost of trajectories in a variety of moving object management system containing transportation.

• Journal of Internet Computing and Services
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• v.10 no.6
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• pp.51-79
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• 2009

Today the service industry is growing, and differentiated services for marketing and service quality is emerging as a serious problem. Until now, the WebCam is used for observation, and the negative aspects, such as from a human rights issue has become. Discipline and Punish is not to use a webcam to customer satisfaction research is needed. Therefore, wireless monitoring in WebCam service quality of the service reconfiguration and service quality factors for the configuration of the customer's preference regarding how research was recognized. Configuration of the service quality factors WebCam service customer satisfaction and customer loyalty was to identify factors that affect. These services to study the correlation between the quality variables WebCam provides wireless monitoring services for the preschool and children, a survey of the house. Configuring a wireless monitoring service quality in order to research the factors WebCam video quality and transmission speed, mobility and portability, convenience, visibility, reliability, and the interaction of the castle set. Severely and video quality and transmission speed, visibility, reliability, customer satisfaction, the interaction factors are said. Inclination to participate in social issues, innovation, digital devices that use a skilled, depending on the difference in the service quality has been confirmed. However, the age and quality of service awareness and job types showed a low correlation, and the marketing of these results will be discussed and how that can be used.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.21-26
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• 2016

This paper presents a step-down DC-DC buck converter with a CCM/DCM dual-mode function for the internal power stage of portable electronic device. The proposed converter that is operated with a high frequency of 1 MHz consists of a power stage and a control block. The power stage has a power MOS transistor, inductor, capacitor, and feedback resistors for the control loop. The control part has a pulse width modulation (PWM) block, error amplifier, ramp generator, and oscillator. In this paper, an external capacitor for compensation has been replaced with a multiplier equivalent CMOS circuit for area reduction of integrated circuits. In addition, the circuit includes protection block, such as over voltage protection (OVP), under voltage lock out (UVLO), and thermal shutdown (TSD) block. The proposed circuit was designed and verified using a $0.18{\mu}m$ CMOS process parameter by Cadence Spectra circuit design program. The SPICE simulation results showed a peak efficiency of 94.8 %, a ripple voltage of 3.29 mV ripple, and a 1.8 V output voltage with supply voltages ranging from 2.7 to 3.3 V.

• Korean Journal of Construction Engineering and Management
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• v.21 no.5
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• pp.11-19
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• 2020

A daily progress monitoring and further schedule management of a construction project have a significant impact on the construction manager's decision making in schedule change and controlling field operation. However, a current site monitoring method highly relies on the manually recorded daily-log book by the person in charge of the work. For this reason, it is difficult to take a detached view and sometimes human error such as omission of contents may occur. In order to resolve these problems, previous researches have developed automated site monitoring method with the object recognition-based visualization or BIM data creation. Despite of the research results along with the related technology development, there are limitations in application targeting the practical construction projects due to the constraints in the experimental methods that assume the fixed equipment at a specific location. To overcome these limitations, some smart devices carried by the field workers can be employed as a medium for data creation. Specifically, the extracted information from the site picture by object recognition technology of CNN model, and positional information by GIPS are applied to update 4D BIM data. A standard CNN model is developed and BIM data modification experiments are conducted with the collected data to validate the research suggestion. Based on the experimental results, it is confirmed that the methods and performance are applicable to the construction site management and further it is expected to contribute speedy and precise data creation with the application of automated progress monitoring methods.

• Journal of the Korea Society of Computer and Information
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• v.18 no.11
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• pp.255-264
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• 2013

This research was conducted to analyze parents' attitudes on the issues related to the Smart Education Initiative Korea. The questions included the usefulness of major digital tools for educational purposes, knowledge on the Smart Education, necessity for better educational methods, and Bring Your Own Devices (BYOD) policy. A total of 432 response cases from the parents were analyzed considering the parents' age, academic level, and income. As a result, parents regarded desktop PCs as more effective tools for learning when compared to tablet PCs. Meanwhile, mobile devices and SNSs were hardly considered as instructional tools. Second, familarity and understanding of the Smart Education were proportional to household income and mothers' education levels. Third, parents needed for the change in educational methods and agreed with the importance of students' self-regulated learning, collaboration, inquiry ability and creativity. Fourth, regarding BYOD, parents were willing to buy devices with a reasonable price. In conclusion, it is required to reflect the results of the study when implementing the Smart Education throughout the nation.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.1
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• pp.9-15
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• 2019

Here, we present a facile route to fabricate a vertically stacked 3D porous structure-based triboelectric nanogenerator (TENG) that can be used to harvest energy from the friction in a repetitive contact-separation mode. The unit component of TENG consists of thin Al foil electrodes integrated with microstructured 3D foams such as Ni, Cu, and polyurethane (PU), which provide advantageous tribo-surfaces specifically to increase the friction area to the elastomeric counter contact surfaces (i.e., polydimethylsiloxane, PDMS). The periodic contact/separation-induced triboelectric power generation from a single unit of the 3D porous structure-based TENG was up to $0.74mW/m^2$ under a mild condition. To demonstrate the potential applications of our approach, we applied our TENGs to small-scale devices, operating 48 LEDs and capacitors. We envision that this energy harvesting technology can be expanded to the applications of sustainably operating portable electronic devices in a simple and cost-effective manner by effectively harvesting wasted energy resources from the environment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.4
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• pp.827-839
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• 2012

A cell phone is very close to the user and therefore should be considered in digital forensic investigation. Recently, the proportion of smartphone owners is increasing dramatically. Unlike the feature phone, users can utilize various mobile application in smartphone because it has high-performance operating system (e.g., Android, iOS). As acquisition and analysis of user data in smartphone are more important in digital forensic purposes, smartphone forensics has been studied actively. There are two way to do smartphone forensics. The first way is to extract user's data using the backup and debugging function of smartphones. The second way is to get root permission, and acquire the image of flash memory. And then, it is possible to reconstruct the filesystem, such as YAFFS, EXT, RFS, HFS+ and analyze it. However, this methods are not suitable to recovery and analyze deleted data from smartphones. This paper introduces analysis techniques for fragmented flash memory pages in smartphones. Especially, this paper demonstrates analysis techniques on the image that reconstruction of filesystem is impossible because the spare area of flash memory pages does not exist and the pages in unallocated area of filesystem.