• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.126-127
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• 2003

1차원의 레이저빔을 공간내의 전방향으로 퍼트리는 새로운 광학기기인 중공형 원통 프리즘에 대해 보고하고자 한다. 중공형 원통 프리즘은 아래의 그림 1과 같이 속이 빈 유리튜브의 구조를 가진다. 레이저광이 유리관의 표면에 입사되면 반사 및 굴절의 현상이 나타난다. 일반적으로 유리는 굴절률이 공기보다 높아 내부반사가 여러 번 일어나므로 유리관 표면에 입사된 레이저빔은 유리관의 곡면을 따라 진행하면서 반사 또는 굴절의 과정을 반복적으로 거치게 된다. (중략)

• Journal of the Korean Institute of Gas
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• v.19 no.1
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• pp.23-27
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• 2015

The stress and deformation behavior safeties of cylindrical hollow rollers have been analyzed by the finite element method, and investigated for over design capability based on the computed results. According to the stress analysis result which is related to the strength of a hollow roller, the maximum stress of 39.8MPa in which is operated near the bearing for supporting a hollow roller structure is overestimated design as 15.9% level compared with a yield strength, 250MPa of a steel material. And the maximum deformation of 0.032mm in which is operated at the middle span of a total length of cylindrical hollow rollers is very small and sufficiently safe compared with a total length and a thickness of a hollow roller. Thus, the FEM computed results for a stress and deformation indicate that a current FEM analysis model of cylindrical hollow rollers is over designed.

• Tunnel and Underground Space
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• v.23 no.5
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• pp.362-371
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• 2013

We conducted hollow cylinder tensile strength tests and Brazilian tests in Seokmo granite to measure tensile strength necessary for estimating the magnitude of the maximum horizontal principal stress in hydraulic fracturing stress measurements. Two different pressurization rates were used in hollow cylinder tests. Tensile strengths were determined to be higher at higher pressurization rate, which suggests that tensile strength should be measurement at the same rate used in actual in situ hydraulic fracturing tests. Considering the effect of pressurization rate and specimen size on tensile strength, the hollow cylinder tests and Brazilian tests yield similar results each other. This demonstrates that Brazilian tests can be utilized to produce representative tensile strengths for interpretation of hydraulic fracturing test results.

• Journal of the Korean Institute of Gas
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• v.18 no.1
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• pp.41-45
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• 2014

This paper presents an analytical study on the displacement behavior safety of cylindrical hollow rollers. Using the finite element method, the hollow roller with Y-shaped column structures between three tubes has been developed to analyze the displacement behavior safety. For the same dimension and weight of two hollow roller models, the displacement behavior safety of a typical hollow roller is lower 4~6.6% than that of the newly designed hollow roller with Y-shaped column structures between three tubes. Thus, this paper recommends Y-shaped hollow roller for increasing the roller strength safety and decreasing a total roller weight, which may save a consuming electrical energy.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.1
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• pp.103-109
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• 1983

본 논문은 저온용 원통형 저장 탱크를 2층으로 된 적층형 복합재료로 가정하여 각 층의 온도분포 를 해석하였다. 이 중공 원통의 외벽에서는 원주방향으로 임의의 열유속을 받고, 주위 온도는 주 기적으로 변하며 내외벽에서는 대류가 일어나고, 탱크벽의 초기온도 분포는 임의의 함수라는 가 정하에 Fourier cosine 변환과 Green 함수를 도입하여 해석하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.286-290
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• 1996

수중 음향센서로서 최근에 많이 연구되고 있는 광섬유 하이드로폰(fiber optic hydrophone)의 성능을 예측하기 위하여 광섬유의 편광특성(polarization)에 따른 정규화 감도식 (normalized sensitivity)을 유도하였다. 본 연구에서 사용된 하이드로폰은 광섬유가 끝단이 막힌 중공 원통형 맨드럴(mandrel)에 감긴 구조이며 음압이 하이드로폰에 작용할 때 응력 관계식을 이용하여 정규화 감도식을 유도하였으며 유도된 감도식을 맨드럴의 내외경비에 따라 특성을 수치해석하였다. 균일한 재질의 광섬유에서 맨드럴의 내외경비의 값이 클수록 그리고 맨드럴의 탄성계수의 값이 작을수록 감도가 증가함을 관찰 하였다.

• Journal of the Korean Institute of Gas
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• v.18 no.2
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• pp.10-15
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• 2014

In this paper, the displacement and stress strength safeties have been presented for cylindrical hollow rollers of a wire saw machine. Using the finite element method, the hollow roller with Y-shaped shift and vertical columns between three tubes has been developed to analyze the displacement behavior and stress strength safeties. For the same diameter and length of hollow roller models with a different weight, the displacement behavior safety of Y-shaped shift column and vertical column models is heavily depending on the total length of a hollow roller, which is closely related to the bending moment of a hollow roller structure. But, the stress strength of a hollow roller is more influenced by the cross sectional area of a hollow roller for the similar weight. Thus, this paper recommends Y-shaped hollow roller for increasing the roller strength safety and decreasing a total roller weight.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.176.1-176
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• 2003

제주지역 양조산업의 산업화 기술 개발의 일환으로 제주지역의 대표적인 전통 좁쌀 약주 제품에 대하여 유통 과정 중에 발생하는 침전 형성을 방지하는 기술을 개발하기 위하여 여과 공정 개선에 관한 연구를 실시하고 개선 방안을 제시하였다. 각종 공극 크기의 유리 막 여과지와 중공사막 카트리지 여과 연구 결과, 이 좁쌀 약주 제품에서 대부분이 침전 형성 가능한 입자들은 1.2$\mu\textrm{m}$여과 매질 공극 크기에 의한 여과에 의하여 제거 되여 보통의 소비에 문제가 되는 침전은 잘 않되는 것으로 조사되었다. 현재 제품 제조 현장에서 사용되고 있는 l$\mu\textrm{m}$ 공극 크기 원통형 정밀 여과기인 경우 이론적으로는 합당하나 여과 매질에 대한 산업 인 공극 크기에 대한 오차 한계인 $\pm$20-30% 때문에 일부제품에서 침전 발생하는 것으로 분석되었다. 또한 4$^{\circ}C$와 실온을 48시간씩 반복하면서 3개월간 저장 중 유리 막 여과지인 경우는 0.7$\mu\textrm{m}$ 공극크기의 여과에서도 세밀한 관찰에 의하여 침전형성이 관찰되었으나 중공사막인 경우에는 0.45$\mu\textrm{m}$에서도 전연 침전형성이 관찰되지 않았다. 따라서 완벽한 침전 형성 방지를 위해서는 최종 여과공정에 중공사막 여과 시스템 도입이 효과적이며, 설계 기준은 0.45$\mu\textrm{m}$ 공극과 내경 1mm정도의 중공사막을 유효 여과 면적 1$m^2$정도를 가지도록 하는 중공사막 여과 시스템인 경우 여과 능력은 약400ι/hr로 계산되었다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.7
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• pp.626-633
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• 2012

In this paper, sound pressure sensitivity of the fiber optic acoustic sensor according to sensor direction and mandrel material were investigated experimentally. Three different directions were selected as stand, lay, and hole. Hollow cylinder type mandrel dimension is 30 mm in outer diameter, 45 mm in length, and 2 mm in thickness, and about 50 m optical fibers were wounded on the surface of the mandrel. Non-directional sound speaker was used as a sound source. Sagnac interferometer and single mode fiber, a laser with 1,550 nm in wavelength, $2{\times}2$ coupler were used. Based on the experimental results, lay direction's sensitivity is the highest in the frequency range of 2 kHz~4 kHz. 'PTFE+carbon' material is more sensitive than PTFE in the frequency range of 5 kHz~20 kHz. Sound pressure detection sensitivity depends on the mandrel direction and material under certain frequency.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1552-1557
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• 2004

This paper introduced about characteristics on the non-steady heat transfer of STS 304 hollow cylinder, In the non-steady state, the specific heat and conductivity are depended on the temperature variations, and these properties affect to the governing equation on heat conduction. But the most of numerical analysis on heat conduction is assumed to constant properties which is conductivity and specific heat. Assuming that conduction is assumed to constant properties which is conductivity and specific heat. Assuming that the properties are reacted sensitively, the numerical results can have the difference of between constant properties with non-constant properties. The main parameters are specific heat and conductivity. The temperature distributions of the STS 304 hollow cylinder became in steady state after 4 minutes in case of the constant properties. As the conductivity in varied with temperature, the temperature distributions became in steady state after 15 minutes. Therefore, a numerical analysis of the non steady state heat transfer will has to apply that conductivity varied with temperature.