• Korean Journal of Materials Research
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• v.28 no.7
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• pp.411-416
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• 2018

Tungsten oxide($WO_3$) films with uniform surface morphology are fabricated using a spin-coating method for applications of electrochromic(EC) devices. To improve the EC performances of the $WO_3$ films, we control the heating rate of the annealing process to 10, 5, and $1^{\circ}C/min$. Compared to the other samples, the $WO_3$ films fabricated at a heating rate of $5^{\circ}C/min$ shows superior EC performances for transmittance modulation(49.5 %), response speeds(8.3 s in a colored state and 11.2 s in a bleached state), and coloration efficiency($37.3cm^2/C$). This performance improvement is mainly related to formation of a uniform surface morphology with increased particle size without any cracks by an optimized annealing heating rate, which improves the electrical conductivity and electrochemical activity of the $WO_3$ films. Thus, the $WO_3$ films with a uniform surface morphology prepared by the optimized annealing heating rate can be used as a potential candidate for performance improvement of the EC devices.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.2
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• pp.125-131
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• 2014

This study is aim to investigate and propose ways to improve real condition of the accessibility compliance that is required to use mobile applications for special education student with a disabilities. Especially, expert examined some mobile applications with 12 items out of 15 mobile application accessibility guidelines from Ministry of Science, ICT and Future Planning which is helpful for people with physical disabilities such as difficulty in seeing, hearing, and upper limb. Based on the results of expert evaluation, we analyzed the problem for mobile applications without accessibility compliance and presents improvement plans for people with disabilities to use mobile applications.

• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.64-70
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• 2019

Wireless sensors have been developed in numerous ways for enhancing the convenience of installation, management and maintenance of sensors. Energy harvesting wireless sensors, which can collect energy from the external environment for permanent usage without the need of recharging and exchanging batteries, have been developed and employed used in Internet of Things and at various industrial sites. Energy harvesting wireless sensors are significantly affected by the sensor lifespan to sudden variation in the external environment. Furthermore, reduction in the sensor operating timespan can greatly affect the characteristics of the devices connected through a network. In this paper, a system performance index is proposed that can comprehensively evaluate the lifespan of a solar cell wireless sensor, determine the characteristics of devices connected to the associated network, and recommend dynamic power distribution control for improving the system performance index. Improvement in the system performance index was verified by applying the proposed dynamic power distribution control to an air conditioner network system using a solar cell wireless sensor. Obtained results corroborate that the dynamic power distribution control can extend the lifespan of the incorporated wireless sensor and reduce the air conditioner's power consumption.

• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.251-258
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• 2016

Recently, the demand for fast storage devices is rapidly increasing in cloud platforms, social network services, etc. Despite the development of fast storage devices, the traditional Linux I/O stack is not able to exploit the full extent of the performance improvement since it has been optimized for disk-based storage devices. In this paper, we propose an optimized I/O stack which can fully utilize the I/O bandwidth and latency of fast storage devices. To this end, we design a new I/O interface to replace the current block I/O interface and optimize our I/O interface. Our optimized I/O interface bypasses operations/layers in block I/O subsystems of the current Linux I/O stack to fully exploit fast storage devices. We also optimize the Linux file systems such as ext2 and ext4 to run on our I/O interface. We evaluate our I/O stack with multiple benchmarks and the experimental results show that our I/O stack achieves 1.7 times better throughput compared to traditional Linux I/O stack.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.633-636
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• 2003

In this work, We, for the first time, present the effects of the thermal annealing of the W/SiO$_2$ multi-layer quarter wavelength reflectors on the resonant properties of the ZnO-based SMR devices. In order to improve the resonant properties of the SMR devices, we annealed thermally the reflectors formed on a silicon substrate using a RF magnetron sputtering technique. As a result, the resonant properties of the SMR devices were observed to strongly depend on the annealing conditions applied to the reflectors. The SMR devices with the reflectors annealed at 40$0^{\circ}C$/30min showed excellent resonance properties as compared to those with the reflectors non-annealed (as-deposited). The newly proposed simple thermal annealing process will be very useful to more effectively improve the resonant properties of the future SMR devices with W/SiO$_2$ multi-layer quarter wavelength reflectors.

• KIEAE Journal
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• v.16 no.5
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• pp.65-71
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• 2016

Purpose : The solar shading device carries out roles in a reduction of the cooling load and an improvement of the thermal comfort of occupants by adjusting incident solar radiation. In addition, The shading device enhances the visual sensation comfort by controlling the optical properties. In order to improve building performance and comfort of occupancy, interests in application of the shading devices are getting increasing. This study investigated the application and effectiveness of the external shading device design using statistical analysis. The outcome of this paper could be utilized for the realization of status quo and for an estimation of effectiveness of the shading device Method : The period of data gathering was between 2003 and 2014 and total 459 cases of practical building project were investigated. Firstly, this study defined qualification of the shading devices; the shading device should have minimum protruding lengths of 150mm to outside and have the function of shading control. This paper investigated application rate of the shading device in real project, regional rate of application, annual change of application, materials and types. Result : The statistical analysis showed that the application rate of shading devices was 25.7% in total 459 building design projects. The application rate in central and southern region was 25.3% and 27.0% respectively. Meanwhile, Jeju region showed 22.2%, which was the lowest rate although this area needs more shading devices. The application number of the shading device was the smallest in 2007, but the rate gradually increased after that. The applications was the largest in 2014 due to growing interest of the shading devices in the building.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.601-611
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• 2011

The paper deals with the selection of 3D display devices in accordance with the user's conveniences and accuracy of spatial information by applying 3D display devices to Spatial Information Update System (SIUS) which generate edit and update digital thematic maps. After applying different manufacturer's 3D display devices to SIUS, aerial images acquired from the stereo images were displayed through the devices and spatial information was extracted from the displayed 3D images. Assessment of 3D display devices were based on quantitative and qualitative analysis on accuracy of spatial information and user's conveniences. Planar's PL2020 and Redrover's Tru3Di 3D monitor has expressed outstanding display environment in 3D related tasks for the generation of spatial information compared to other 3D display devices. System improvement is expected regarding accuracy of spatial information, work efficiency and user's conveniences.

• Journal of the Korea Society of Computer and Information
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• v.14 no.4
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• pp.111-117
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• 2009

Improvement of Wireless internet and handheld devices makes it possible that users can use various multimedia services. But, access point devices are needed while using handheld devices, and those devices use virtual network address for networking. For that reason, end-users hardly use the 1:1 voice or video chat, and messenger service that require direct communications between devices. Also, service providers need central server for relaying packets from terminals to others, the traffic and costs of relaying go high, so real-time massive data transmission services are restrictively provided. In this study, we apply TCP/UDP hole punching technique to those applications. And we implement service that supports real-time multimedia direct transmission between equipments that use virtual network addresses.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2406-2414
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• 2013

The data-driven IT project model has been improved by adding processes such as analysis/design of data structure and channels of data collection/distribution, application of data standard and securing the flexibility in IT convergence devices data configuration on existing informatization project procedure driven by HW and SW function. This model focused on the evaluation of improvement effect which warrants data flexibility of IT convergence device. IT convergence device was divided into sensor and reactor and a situation when new information system is additionally linked to these devices was assumed. The system improvement complexity and index on network environment were estimated and they were compared to existing method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1070-1073
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• 2003

We have studied the characteristics of organic light-emitting diodes(OLEDs) with the PTFE buffer layer. The OLEDs have been based on the molecular compounds, N,N'-diphenyl-N,N'-bis (3-methylphenyl)-1, 1'- biphenyl-4, 4'-diamine (TPD) as a hole transport, tris(8-hydroxyquinolinoline) aluminum (III) ($Alq_3$) as an electron transport and the Polytetrafluoroethylene (PTFE) as a buffer layer. The devices of structure were fabricated ITO/PTFE/TPD(40nm)/$Alq_3$(60nm)/Al( 150nm) to see the effects of the PTFE buffer layer in organic EL devices. The thickness of the PTFE layer varied from 0.5 to 10[nm]. We were measured Current-Voltage-Luminance Characteristics and Luminance efficiency due to the variation of PTFE thickness. the PTFE layer was reported that helped to enhance the hole tunneling injection and effectively impede induim diffusion from the ITO electrode. We have obtained an improvement of luminance efficiency when the PTFE thickness is 0.5[nm] is used. The improvement of efficiency of is expected due to a function of hole-blocking of PTFE in OLEDs.