• Proceedings of the Optical Society of Korea Conference
• /
• 2002.07a
• /
• pp.168-169
• /
• 2002

일반적인 광섬유가 실리카로 만들어진 클래딩과 이보다 약간 굴절률이 높은 코어로 구성되어 있는 것과는 달리 광자결정 광섬유(photonic crystal fiber 또는 다공성 광섬유(holey fiber))는 코아와 클래딩이 순수 실리카로 구성되어 있다 클래딩의 효과를 주기 위해 광섬유 축을 따라서 규칙적인 공기구멍 다발을 형성하여 준다. 광자결정 광섬유는 특이한 광학적 특성 때문에 최근에 활발히 연구되어 지고 있다. 공기구멍의 구조를 조절함으로써 넓은 파장 영역에서 단일 모드로 진행하고(1), 아주 큰 분산을 갖게 할 수 lT고, hem 반경을 조절 할 수 있으며, 특이한 분산 특성과 이의 조절이 가능하다. (중략)

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.7
• /
• pp.561-566
• /
• 2014

Our Korean traditional cultural inheritance Bangpae Kite has the stable rectangular shield shape decorated with artistic paint or poem and a good flight performance due to the central wind hole. In this paper, to analyse the wind hole effect to kite performance we performed the wind tunnel testing of the various design factor of kite model and air flow visualization passing through the wind hole. As the result of aerodynamic analysis, we knew that the wind hole of kite displays similar function of slot system for the wing high lift device. This fact demonstrates that our ancestor understood the function of slot system and applied effectively to the development of kite flight performance.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1995.05b
• /
• pp.727-732
• /
• 1995

사용후핵연료 중간저장 시설의 누수사고시 예상되는 핵연료봉의 온도상승을 SFUEL 컴퓨터 코드 분석결과에 따른 실제 $UO_2$의 산화거동을 실험하였다. 외기 온도 38$^{\circ}C$에서 환기회수가 시간당 0, 1, 2회인 조건에서 저장용기 밑바닥 구멍 크기가 2.54, 5.08, 7.62 cm인 경우의 실험결과 환기회수 0회 바닥구멍 크기 2,54 cm 일 때 약 15시간 후 건전성 상실(0.6% 무게증가)이 일어났으며 환기회수 2회 바닥구멍 크기 7.62 cm 일 때는 약 21시간 이후에 건전성 상실이 일어나 가장 느렸다. 바닥구멍 크기가 증가할수록 공기 순환비의 영향을 크게 받으며, 또 외기 온도가 낮을 수록 공기 순환비의 영향을 크게 받았다.

• Corrugated packaging logistics
• /
• v.9 no.43
• /
• pp.78-85
• /
• 2002

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.4
• /
• pp.243-254
• /
• 2020

Korean traditional kite has the unusual shape of the elongated rectangle with the center hole. The aerodynamic forces are numerically computed on Korean traditional kite with aspect ratio 1:1.5 by using FLUENT software. Simulating the flight of the kite with various diameters of the center hole, the present study has investigated the role of the center hole as well as the effect of diameter of the center hole. The center hole plays a role in relieving the sudden increase of tension associated with fast rewinding of the kite thread in kite fighting, thereby enabling faster rewinding of the kite thread. The proper diameter of the center hole is 1/3 of the width.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2012.05a
• /
• pp.405-406
• /
• 2012

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.32 no.4
• /
• pp.381-385
• /
• 1996

This paper described to experiment and analyze for the characteristic of underwater airbubble curtain which was generated by the air - bubble curtain generating unit consisted with air compressor (290l/min x 1.5Kw) and air tank(10kgf/$cm^2$) in order to provide foundation source for guiding fish schools. To layout the air - bubble curtain was made vinyl hoses( $cm^2$ emitting air - pressure, the wider hole interval of hose drilled the higher air - bubble curtain could be formed, and then the horizontal length of air - bubble curtain could be prolonged 45% according to be inclined vertical angle of air - bubble generating hose.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.36 no.2
• /
• pp.191-196
• /
• 2016

Applying diffraction of waves and muffler principle, the theory of macroscopic air ventilation with soundproofing was explained. Soundproofing frequency range can be selected by this method. The sound wave was attenuated at the resonator located between double-layered walls. A soundproof plate was designed and the experiment was processed. There are two air holes of diameter of 5cm and thickness of 8cm on the surfaces per each soundproofing cell. There was a transmission loss of about 25dB and it is more than at least 10dB compared with that of the Comnex technology of wave cancellation by air holes in Japan. Furthermore, there was no soundproof frequency selection in the Comnex technology.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.10
• /
• pp.865-871
• /
• 2014

This study was conducted with the aim of developing a venturi-type air supply system for a microbubble generator. In order to determine the influence of the varying geometry of the venturi tube on the flow characteristics, a computational fluid dynamics (CFD) simulation was performed using the commercial CFD software ANSYS CFX-15. Furthermore, in order to elucidate the effects of variation in major design dimensions such as the air supply hole size, position of holes, and number of holes on the air supply characteristics, two-phase multiflow CFD analysis was performed. The analysis results showed that the starting point of expansion on the venturi tube with 0.75 is the best hole position and that the air supply hole size and the number of holes are linearly proportional to the amount of air.

• Journal of the Society of Disaster Information
• /
• v.17 no.4
• /
• pp.829-838
• /
• 2021

Purpose: The Air Spring Damper System (ASDS) is proposed when existing concrete structures that have not been seismic resistant for economic and technical reasons or low-rise concrete structures that are difficult to earthquake. Method: To conduct a study on the damping force antigen in the kinetic equation of free vibration, we analyze whether this device has damping ability as a damper experimentally and theoretically, and examine the possibility of field application. Result: The air damper system is considered to be more economical than steel hysteresis dampers even if the number of dampers increases due to its easy manufacture and construction and low restrictions on shape, size, material, etc. Conclusion: In an air spring damper system, it is essential to reduce the diameter of the air inlet/outlet hole to improve the damping ratio, and in this case, if the diameter exceeds a certain lower limit, consideration of the compressibility of air is required, so further research is needed.