• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1875-1877
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• 2001

Glaucoma is an eye disease which is caused by abnormal high lOP (Intra Ocular Pressure). High lOP is caused by the aqueous humor which is produced consistently but not drained due to malfunction of the trabecular system which has a role of draining the aqueous humor into the venous system. Currently, there are some methods to treat glaucoma, Among these, the use of implants is increasing in these days due to many problems In other methods. However, conventional implants are passive implants and have critical disadvantage. Therefore, it is needed to develop an active implant which is composed of a valve actuator, pressure sensor, controller, and power supply. In this paper, we make experiment with the fabricated valve actuator in In-vitro experiment, and estimate the in-vivo result using the experimental result and investigate the possibility of the fabricated valve.

• The Journal of Engineering Geology
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• v.21 no.1
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• pp.45-55
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• 2011

We examined the interactions between surface and groundwater through (1) flowmeter logging, (2) measurements of seasonal and vertical changes in temperature within a well, and (3) geochemical analyses of water samples from nine groundwater-monitoring wells. At two wells adjacent to a stream, subsurface water was found to flow from the stream to a surrounding alluvial fan, and the seasonal change in groundwater temperature is similar to those of surface water and air. Geochemical analyses at two wells indicated hydro-geochemical features affected by streamwater inflow, showing seasonal variations. Accordingly, these two wells are located in an area with active interaction between surface water and groundwater. The Thermochron I-button used in the present study is useful for this type of study of groundwater?surface water interaction because of its low cost and small size.

• Journal of Sensor Science and Technology
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• v.29 no.4
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• pp.215-219
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• 2020

MnCo₂S₄/CoS₂ electrode with highly accessible electroactive sites is prepared using the hydrothermal method. The electrode exhibits an areal capacitance of 0.75 Fcm^-2 at 6 mAcm^-2 in 1 M KOH. The capacitance is further increased to 2.06 Fcm^-2 by adding K₃Fe(CN)₆ and K₄Fe(CN)₆ (a redox couple) to KOH. This increment is associated with the redox-active properties of cobalt and manganese transition metals, as well as the ion pair of [Fe(CN)₆]^-3/[Fe(CN)₆]^-4. The capacitance retention of the MnCo₂S₄/CoS₂ electrode is 87.5% for successive 4000 charge-discharge cycles at 10 mAcm^-2 in a composite electrolyte system of KOH and ferri/ferrocyanide. The capacitance enhancement is supported by the lowest equivalent series resistance (0.62 Ωcm^-2) of MnCo₂S₄/CoS₂ in the presence of redox additive couple compared with the bare KOH electrolyte.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.1
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• pp.61-70
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• 2008

This paper presents the flexible MEMS transmitter based on flexible printed circuit board or FPCB, which can be transformed to arbitrary shape. The FPCB is suitable to fabricate light weight and small size modules with the help of its thin thickness. Moreover a module based on FPCB can be attached on the arbitrary curved surface due to its flexible enough to be lolled up like paper. In this paper, the flexible MEMS transmitter integrated on FPCB for a short-distance sensor network which is based on orthogonal frequency division multiplexing(OFDM) communication system is proposed. The active device of the proposed flexible MEMS transmitter is fabricated on InGaP/GaAs HBT process which has been used for power amplifier design to take advantages of high linear and high efficient characteristics. Moreover, the passive devices such as the filter and signal lines are integrated and fabricated on the FPCB board. The performance of the fabricated flexible MEMS transmitter is analyzed with EVM characteristics of the output signal.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.2
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• pp.353-360
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• 2017

The Internet of Things(IoT) security has more need than a technical problem as it needs series of regulations and faultless security system for common purposes. So, this study proposes an efficient key management in order that can be trusted IoT data in cloud computing. In contrast with a key distribution center of existing sensor networks, the proposed a federation key management of cloud proxy key server is not central point of administration and enables an active key recovery and update. The proposed key management is not a method of predetermined secret keys but sharing key information of a cloud proxy key server in autonomous cloud, which can reduce key generation and space complexity. In addition, In contrast with previous IoT key researches, a federation key of cloud proxy key server provides an extraction ability from meaningful information while moving data.

• Korean Institute of Interior Design Journal
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• v.22 no.1
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• pp.203-210
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• 2013

With digital technology, space design is developing in a new direction with the changing paradigm. The space creates an interactive environment by motivating the User's active participation through the digital madia. In this social stream, it is very important to think about how this new paradigm affects the spatial design and the interactions between social changes and spatial design paradigm, so that we can understand design paradigm of our time. Hence, in this research, we will think about social characteristic and design paradigm of digital age by questioning how spatial design is changing in the digital age and how digital technology is affecting spatial design. this study analyzed about the space form, digital media setting, user interactivity of the examples of experience space using digital media. fields of our society, interactive space with the concept of HCI became a big issue in environmental design field. In this interactive space, various types of informative factors of the given space are sent using sensor and computer networking technology to the main system, and the main computer system sends manipulated output media to interactive devices. So, a user's movement in the space is more than just a movement itself user's movement now forms a important spatial structure that leads the narrative of the space. Researcher will analyze the characteristic of a public space and progress this research supposing that space needs this interactive design.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.4
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• pp.436-440
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• 2008

In IEEE 802.15.4 beacon-enabled mode, performance decreases as the number of devices competing in the contention access period(CAP) increases. In this letter, we propose partitioned contention access mechanism(PCAM) to compensate performance degradation. In PCAM, the PAN coordinator divides CAP into two sub-periods and activity of devices is delimited in their assigned sub-periods. Since PCAM reduces the number of devices which compete at the same time by half, collision probability between transmitted frames can be reduced. In addition, devices can save their power consumption because PCAM shorten the duration that devices stay in active state into half. We perform simulations to compare the performance of PCAM with that of the IEEE 802.15.4 standard. From the result, PCAM yields better performance than IEEE 802.15.4 standard.

• The Journal of the Korea Contents Association
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• v.19 no.11
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• pp.12-21
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• 2019

In the era of the Fourth Industrial Revolution, drones have become a flexible device that can be integrated with new technologies. The drones were originally developed as military unmanned aircraft and are now being used in various fields. In the environment and weather observation area, the atmospheric boundary layer is near the surface where the atmosphere is the most active in the meteorological phenomenon and has a close influence on human activities. In order to carry out the study of these atmospheric boundary layers, it is necessary to observe precisely the lower atmosphere and secure the observation technology. The drones in the meteorological field can be used for meteorological observations at a relatively low maintenance cost compared to existing equipment. When used in conjunction with various sensors, the drones can be widely used in atmospheric boundary layer and local meteorological studies. In this study, the possibility of meteorological observations using drones was confirmed by conducting vertical meteorological (temperature and humidity) observation experiments equipped with a combined meteorological sensor and a radio sonde on drones owned by NIMS.

• Journal of Sensor Science and Technology
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• v.18 no.2
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• pp.110-115
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• 2009

Polystyrene (PS) microspheres were used to good advantage as a template material to prepare macroporous $TiO_2$ thin films. This is enabled to run the thermal decomposition of the PS without the collapsing of the 3-D macroporous framework during the calcination step. $TiO_2$ thin films were deposited onto the colloidal templated substrates at room temperature by RF sputtering, and then samples were thermally treated at $450^{\circ}C$ for 40.min in air to remove the organic colloidal template and induce crystallization of the $TiO_2$ film. The macroporous $TiO_2$ thin film exhibited a quasi-ordered partially hexagonal close-packed structure. Burst holes, estimated to be formed during PS thermal decomposition, are seen as the hemisphere walls. the inner as well as the outer surfaces of the hollow hemispheres formed by the method of thermal decomposition can be easily accessed by the diffusing gas species. As a consequence, the active surface area interacting with the gas species is expected to be enlarged about by a factor of fourth as large as compared to that of a planar films. Also the thickness at neighboring hemisphere could be controlled a few nm thickness. If the acceptor density becomes as large that depletion width reaches those thickness, the device is in the pinch off-situation and a strong resistance change should be observed.

• Korean Journal of Materials Research
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• v.22 no.5
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• pp.237-242
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• 2012

We report on the NO gas sensing properties of Al-doped zinc oxide-carbon nanotube (ZnO-CNT) wire-like layered composites fabricated by coaxially coating Al-doped ZnO thin films on randomly oriented single-walled carbon nanotubes. We were able to wrap thin ZnO layers around the CNTs using the pulsed laser deposition method, forming wire-like nanostructures of ZnO-CNT. Microstructural observations revealed an ultrathin wire-like structure with a diameter of several tens of nm. Gas sensors based on ZnO-CNT wire-like layered composites were found to exhibit a novel sensing capability that originated from the genuine characteristics of the composites. Specifically, it was observed by measured gas sensing characteristics that the gas sensors based on ZnO-CNT layered composites showed a very high sensitivity of above 1,500% for NO gas in dry air at an optimal operating temperature of $200^{\circ}C$; the sensors also showed a low NO gas detection limit at a sub-ppm level in dry air. The enhanced gas sensing properties of the ZnO-CNT wire-like layered composites are ascribed to a catalytic effect of Al elements on the surface reaction and an increase in the effective surface reaction area of the active ZnO layer due to the coating of CNT templates with a higher surface-to-volume ratio structure. These results suggest that ZnO-CNT composites made of ultrathin Al-doped ZnO layers uniformly coated around carbon nanotubes can be promising materials for use in practical high-performance NO gas sensors.