• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.100-101
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• 2012

The plasma damage free and room temperature processedthin film deposition technology is essential for realization of various next generation organic microelectronic devices such as flexible AMOLED display, flexible OLED lighting, and organic photovoltaic cells because characteristics of fragile organic materials in the plasma process and low glass transition temperatures (Tg) of polymer substrate. In case of directly deposition of metal oxide thin films (including transparent conductive oxide (TCO) and amorphous oxide semiconductor (AOS)) on the organic layers, plasma damages against to the organic materials is fatal. This damage is believed to be originated mainly from high energy energetic particles during the sputtering process such as negative oxygen ions, reflected neutrals by reflection of plasma background gas at the target surface, sputtered atoms, bulk plasma ions, and secondary electrons. To solve this problem, we developed the NBAS (Neutral Beam Assisted Sputtering) process as a plasma damage free and room temperature processed sputtering technology. As a result, electro-optical properties of NBAS processed ITO thin film showed resistivity of $4.0{\times}10^{-4}{\Omega}{\cdot}m$ and high transmittance (>90% at 550 nm) with nano- crystalline structure at room temperature process. Furthermore, in the experiment result of directly deposition of TCO top anode on the inverted structure OLED cell, it is verified that NBAS TCO deposition process does not damages to the underlying organic layers. In case of deposition of transparent conductive oxide (TCO) thin film on the plastic polymer substrate, the room temperature processed sputtering coating of high quality TCO thin film is required. During the sputtering process with higher density plasma, the energetic particles contribute self supplying of activation & crystallization energy without any additional heating and post-annealing and forminga high quality TCO thin film. However, negative oxygen ions which generated from sputteringtarget surface by electron attachment are accelerated to high energy by induced cathode self-bias. Thus the high energy negative oxygen ions can lead to critical physical bombardment damages to forming oxide thin film and this effect does not recover in room temperature process without post thermal annealing. To salve the inherent limitation of plasma sputtering, we have been developed the Magnetic Field Shielded Sputtering (MFSS) process as the high quality oxide thin film deposition process at room temperature. The MFSS process is effectively eliminate or suppress the negative oxygen ions bombardment damage by the plasma limiter which composed permanent magnet array. As a result, electro-optical properties of MFSS processed ITO thin film (resistivity $3.9{\times}10^{-4}{\Omega}{\cdot}cm$, transmittance 95% at 550 nm) have approachedthose of a high temperature DC magnetron sputtering (DMS) ITO thin film were. Also, AOS (a-IGZO) TFTs fabricated by MFSS process without higher temperature post annealing showed very comparable electrical performance with those by DMS process with $400^{\circ}C$ post annealing. They are important to note that the bombardment of a negative oxygen ion which is accelerated by dc self-bias during rf sputtering could degrade the electrical performance of ITO electrodes and a-IGZO TFTs. Finally, we found that reduction of damage from the high energy negative oxygen ions bombardment drives improvement of crystalline structure in the ITO thin film and suppression of the sub-gab states in a-IGZO semiconductor thin film. For realization of organic flexible electronic devices based on plastic substrates, gas barrier coatings are required to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency flexible AMOLEDs needs an extremely low water vapor transition rate (WVTR) of $1{\times}10^{-6}gm^{-2}day^{-1}$. The key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required (under ${\sim}10^{-6}gm^{-2}day^{-1}$) is the suppression of nano-sized defect sites and gas diffusion pathways among the grain boundaries. For formation of high quality single inorganic gas barrier layer, we developed high density nano-structured Al2O3 single gas barrier layer usinga NBAS process. The NBAS process can continuously change crystalline structures from an amorphous phase to a nano- crystalline phase with various grain sizes in a single inorganic thin film. As a result, the water vapor transmission rates (WVTR) of the NBAS processed $Al_2O_3$ gas barrier film have improved order of magnitude compared with that of conventional $Al_2O_3$ layers made by the RF magnetron sputteringprocess under the same sputtering conditions; the WVTR of the NBAS processed $Al_2O_3$ gas barrier film was about $5{\times}10^{-6}g/m^2/day$ by just single layer.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.364-364
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.317-318
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1343-1344
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• 2011

• Journal of the Korean Geotechnical Society
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• v.35 no.7
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• pp.41-50
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• 2019

Gyeongju bentonite is a buffer material primarily considered in Korea and it is highly compacted as a part of an engineered barrier system (EBS) of high-level radioactive waste repository. The compacted bentonite undergoes swelling stress by groundwater penetration and thermal stress by decay heat from a canister. Therefore, the mechanical properties of the compacted bentonite buffer material is crucial for the performance assessment of EBS. This paper aims to evaluate deformation properties of Gyeongju compacted bentonite using seismic methods. Two sets of compacted bentonite specimens were prepared having dry densities of $1.59g/cm^3$ and $1.75g/cm^3$ with water contents of 10.6% and 8.7%. Free-free resonant column tests were performed to measure constrained and unconstrained compression wave velocities. With the measured wave velocities, Young's modulus ($E_{max}$) and constrained modulus ($M_{max}$), material damping ratio ($D_{min}$), and Poisson's ratio at small strain were determined. As results, this paper evaluates the deformation properties of Gyeongju compacted bentonite and compares them with the results of previous researches.

• Korean Institute of Interior Design Journal
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• v.21 no.1
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• pp.3-10
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• 2012

There is a growing awareness that physical barriers affect the level of independence of people with disabilities. Many researchers insist that barrier free design could influence independence living and quality of life of the disabled. The purpose of this study is to find out the effects of accessible design features of house and public facilities on quality of life of disabled people. A total of 189 questionnaires from the disabled who visited public welfare facilities was analyzed. In order to find out what variables among accessible features in housing and public spaces impact quality of life, multiple regression analysis was carried using SPSS 14. The results showed that accessible designs significantly influence quality of life of the disable. The main reason in which the disabled have difficulties when they move outside is a lack of accessible amenities and facilities. Particularly in house design, accessible main entrance route and accessible main entrance door, and removal of floor level significantly affects quality of life of the disabled. For public spaces, accessible main entrance and installation of ramp or removal of floor levels of main entrance and corridor increase quality of life people with disabilities. This paper suggested that the improvement in housing and public space, in which regulation or bylaws do not specify, should be made to increase accessibility for life quality of the disabled.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2009.11a
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• pp.213-216
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• 2009

The purpose of this study is analyzing temporal flow about 20 detailed performance items in the "Housing Performance Grading Indication System". This study try to figure out situations according grade in detailed performance item and to analyze change item about 112 cases(2 cases in 2006, 15 cases in 2007, 46 cases in 2008, 49 cases in 2009), from January 9, 2006 which system is undertaken, to October, 2009. This system consists of 5 main performance section, 14 performance categories and 20 detailed performance items. 5 main performance parts are Noise and Acoustics(Light-weight impact sound control, heavy-weight impact sound control, sound control of toilet, sound control of party wall), Long-life(flexibility, remodeling & maintenance, durability), Landscape & Indoor Environment(landscape, formaldehyde control & ventilation, daylighting, thermal environment), Welfare & Barrier-free(playground and community center, welfare space, barrier-free design), Fire Safety(fire safety, safe place, fire-resisting quality). Total efficiency about housing can understand systematically of 20 perfomance items though this research.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2011.04a
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• pp.172-175
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• 2011

Financial supports for housing for the disabled is limited since a certain amount of budget needs to be distributed for a number of disabled families. Therefore, it is important to fund renovation for the disabled effectively and properly. Financial and administrative supports for the renovation which intended to improve housing conditions in terms of accessibility (barrier free) and comfort needs to be implemented with larger outcome and smaller budget. The purpose of this study was to investigate various factor such as renovation cost and renovation elements, influence satisfaction of residents with disabilities. Participants of this study are limited to the recipients of financial supports for housing renovation and refurbishment from City of Seoul and Ministry of Heal and Welfare. A total of 155 cases were analyzed using post occupancy survey and analysis of project cost data. Overall, more cost were used for modification for housing condition improvement than the cost for removal of architectural barriers. Renovation cost differences were not apparent among the type and extent of an individual's disabilities. Instead existing housing type and physical condition for the housing affects cost for renovation more significantly. Overall the renovation cost is positively related to resident's satisfaction using regression analysis.

• Journal of Environmental Science International
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• v.16 no.12
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• pp.1383-1392
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• 2007

The purpose of this study is to provide suitable outdoor spaces for Korean elderly, examining characteristics and types of existing outdoor spaces and presenting design guideline of outdoor space for elderly. To do this, this study examined previous research papers and scholastic writings, related to elderly housing, and analyzed twelve cases of elderly housing complex. Additionally evaluation of usage pattern and physical trace carried out on twelve cases. As a result, first, the study showed that outdoor spaces for elderly were classified 5 types; entrance area of housing complex, building entrance area, outdoor living area, in & outdoor neutral area, and parking lots. Outdoor living area is subdivided into residents' public space, green space, health & sports space and landscape space. Characteristics of outdoor space are deeply related to safety, amenity, recognition and efficiency. Second, types of outdoor space in elderly facilities are very limited in verity, just facilitating with rest space, sport space, and garden space. Third, from a standpoint of barrier-free-design, twelve cases are not carefully concerning about outdoor space for elderly.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.6
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• pp.79-82
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• 2017

In this paper, we proposed the wireless communication system using millimeter-wave envelope detector. The sub-harmonic mixer based on schottky barrier diode was used in the transmitter. The receiver was used millimeter-wave envelope detector. The transmitter was composed of schottky diode sub-harmonic mixer, frequency tripler, and horn antenna. The receiver was composed of horn antenna, millimeter-wave envelope detector, low pass filter, base band amplifier, and limiting amplifier. At 1.485 Gbps and 300 GHz, the eye-diagram showed a very good performance as measured by the error free. Communication distance is reduced compared to the heterodyne receiver, but compact and lightweight is possible.