• Korean Journal of Optics and Photonics
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• v.17 no.5
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• pp.396-400
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• 2006

We present a weather-insensitive optical free-space communication method supporting optical packet channels. It operates optical fiber amplifiers in gain-saturation regions. When the propagation loss gets too high, it decreases the average packet rate, or the average packet length, or both, to increase the optical power level launched into the free-space. As a demonstration, we transmit $8{\times}10$ Gigabit Ethernet channels over a terrestrial distance of 2.4 km. One gain-saturated free-space optical repeater is used at the halfway point.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.55.4-56
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• 2018

Linear Astigmatism Free - Three Mirror System (LAF-TMS) is the linear astigmatism free off-axis wide field telescope with D = 150 mm, F/3.3, and $FOV=5.51^{\circ}{\times}4.13^{\circ}$. We report the design and analysis results of its mirrors and optomechanical structures. Tolerance allowance has been analyzed to the minimum mechanical tolerance of ${\pm}0.05mm$ that is reasonable tolerance for fabrication and optical alignment. The aluminum mirrors are designed with mounting flexure features for the strain-free mounting. From Finite Element Analysis (FEA) results of mounting torque and self-weight, we expect 33 - 80 nm RMS mirror surface deformations. Shims and the L-bracket are mounted between mirrors and the mirror mount for optical alignment. The mirror mount is designed with four light-weighted mechanical parts. It can stably and accurately fix mirrors, and it also suppresses some of stray light.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.11
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• pp.957-963
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• 2007

this study, helicopter rotor flow is simulated by using a tightly coupled CFD/FreeWake method to describe wake characteristics and to calculate the flow field and rotor aerodynamics. In this tightly coupled CFD/FreeWake method, freewake model provides the boundary condition required in the CFD calculation and CFD provides the pressure distribution on blade surface used in feewake generation. To show the advantage of this method, the pressure distributions on blade surface of a hovering 2-bladed rotor are compared with other numerical methods. This tightly coupled CFD/FreeWake method shows good accuracy in the predicted results and efficient computation time.

• International Journal of Control, Automation, and Systems
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• v.5 no.4
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• pp.471-478
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• 2007

In this paper, an optimal Wiener-Hopf decoupling controller formula is obtained which is expressed in terms of rational matrices, thereby readily allowing the use of state-space algorithms. To this end, the characterization formula for the class of all realizable decoupling controller is formulated in terms of rational functions. The class of all stabilizing and decoupling controllers is parametrized via the free diagonal matrices and the optimal decoupling controller is determined from these free matrices.

• Kyungpook Mathematical Journal
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• v.54 no.1
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• pp.11-22
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• 2014

The sequence spaces $c^F$(M), $c^F_0$(M) and ${\ell}^F$(M) of fuzzy real numbers with fuzzy metric are introduced. Some properties of these sequence spaces like solidness, symmetricity, convergence-free etc. are studied. We obtain some inclusion relations involving these sequence spaces.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.253-258
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• 2013

In this paper, a free-space material measurement technique is discussed in W-band(75~110 GHz). For the accurate measurement of S-parameters of an MUT(Material Under Test) in free space, a W-band quasi-optical free-space material measurement system, less affected by the measurement environments, is discussed, and GRL(Gated Reflect Line) method for calibrating the measurement system is described. Proposed technique is verified for 'Air' and measurement results for arystal plates of thickness 1.1 mm, 2 mm, 2.75 mm and 5 mm are also shown.

• Archives of Reconstructive Microsurgery
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• v.21 no.2
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• pp.153-158
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• 2012

Purpose: The first web space of the foot has a similar thickness and skin texture of the pulp of the fingers. Moreover, it has a reliable blood vessel and sensory nerve. The purpose of this study was to evaluate the clinical results of the first web space free flap to reconstruct the pulp of fingers. Materials and Methods: Authors have performed 23 cases of first web space free flap to reconstruct the pulp defect of the fingers between June 2004 and May 2009. The age of the patients ranged from 20 years old to 55 years old. The size of the flap ranged from $1{\times}1.5cm$ to $8.5{\times}2.5cm$. The mean flap area was 5.4 cm2. In 4 cases, we elevated the flap including lateral aspect of the big toe and medial aspect of the second toe. And then we made an artificial syndactyly to reconstruct the pulps on two fingers at the same time. In all cases, we performed 1 digital artery and 1 dorsal vein anastomosis. Every donor site that had a small defect healed spontaneously without any additional operations to cover it. Results: Of this type of surgery 21 flaps (91.3%) survived, 2 flaps (8.7%) failed. There was no severe complication in the donor sites. There was no walking disturbance due to the skin defect of the donor site. The static 2 point discrimination in 11 cases that we could check ranged from 3 mm to 15 mm. Conclusion: The authors believe that the first web space free flap of the foot is a good option for the reconstruction of the pulp of the fingers and it has a minimal donor site morbidity.

• Journal of the Korean association of regional geographers
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• v.23 no.2
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• pp.269-287
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• 2017

While Jeju Free International City was promoted to overcome the economic crisis and build a new national competitiveness in the era of globalization, its development vision as 'the hub city of Northeast Asian economy in the $21^{st}$ century' has not been realized. This paper argues that Jeju Free International City to aim for the 'ideal free market model', 'neoliberal space of exception', and 'a new testing ground for neoliberal deregulation policies' has failed due to worsening of socioeconomic and environmental contradictions, growing conflicts in local community, and the logic of equity enforced by the central government. To support this claim, this article reviews the theoretical discussions of special economic zones, examines the shifts in the development visions of Jeju Free International City, and analyzes how Jeju has become a space of exception with the introduction of various exceptional policies and spatial mechanisms.

• Archives of Plastic Surgery
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• v.36 no.6
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• pp.750-754
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• 2009

Purpose: The thoracodorsal vessels have been the standard recipient vessels for the majority of surgeons performing free abdominal flap breast reconstructions. Recently, the internal mammary vessels have been recommended as the first - choice recipient vessels for microvascular breast reconstruction. To approach the internal mammary vessel, 3rd or 4th rib cartilage excision is needed, but this method has some demerits - vessel injury, post operative pain and post operative chest hollowness. So, authors propose the approach method to the internal mammary vessel through intercostal space without rib cartilage resection. Methods: From November, 2008 to May, 2009, 13 patients underwent free abdominal flap breast reconstruction with approach to the internal mammary vessel through intercostal space without rib cartilage resection. Results: The mean patient age was 41.8 years, and the mean height was 159.3 cm. 11 patients underwent immediate breast reconstruction. Free DIEP flap reconstruction was performed in 7 patients, Free TRAM flap was performed in 5 patients, and Free SIEA flap was performed in 1 patient. Except 1 case, approach to the internal mammary vessel was took through 3rd intercostal space, and all width of intercostal space exceeded 1 cm. Conclusion: In the authors' experience, use of approach to the internal mammary vessels without rib cartilage resection method is safe and reliable to overcome demerits of rib cartilage resection method.

• 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.