• Progress in Superconductivity and Cryogenics
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• v.13 no.4
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• pp.18-21
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• 2011

In this work, the yttrium oxide($Y_2O_3$) thin films as the buffer layer were prepared by the simple solution coating and reel-to-reel process on an unpolished metal tape substrate. The $Y_2O_3$ thin films were successfully synthesized by the hydrolysis of yttrium acetate. We have studied the improvement of surface roughness with the concentration of solution(0.1 M, 0.4 M, M) and the number of coatings. The planarization by solution coating process is simple in comparison with the existing polishing process, and it is eco-friendly, and has the benefits of low cost process. The thickness of $Y_2O_3$ films was increased with the $Y_2O_3$ concentration in the solution, and the surface became smoother with the number of coating cycles. Using this process, we have achieved 1.2 nm RMS roughness from a starting roughness of over 31 nm on 25 ${\mu}m^2$ area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.93-96
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• 2004

다층의 산화물 박막 구조를 갖는 coated conductor의 장선 제조를 위해서는 연속 증착 공정이 필요하다. 본 연구에서는 RABiTs와 IBAD 공정을 사용한 texture template을 사용하였으며, 금속 테잎을 연속적으로 이동하면서 증착할 수 있는 박막증착 장치(PLD, sputtering, evaporation)를 구축하여 PVD 방법으로 coated conductor를 제조하였다. $CeO_2/YSZ/Y_2O_3$의 완충층을 sputtering 과 evaporation을 이용하여 2축배향성을 가지는 NiW 위에 연속적으로 증착하였다. YBCO 초전도층은 연속 PLD 방법으로 증착하고, Tc, Ic, XRD, SEM을 통해 그 특성을 분석하였다. 그 결과 RABiTS template을 사용하여 Ic가 34A/cm(@77K)인 0.4m 길이의 coated conductor를 제조하였다. IBAD template를 사용하여 Ic가 34A/cm(@77K)인 0.5m길이의 coated conductor를 제조하였고, Jc는 $1.2MA/cm^2$ 이였다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.570-573
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• 1996

The evaluation test for the operation of rotary type surface mounters which consist of the reel axis, the index table and the X-Y table, has been performed by comparing the new method with the old one in only fields. Because the problem seeking for the optimal operation of rotary type surface mounters, is NP complete, it is almost impossible to get the optimal solutions of large problems. This paper deals with a dynamic network modeling, which can reduce the effort, the cost, and the time used for the performance test of rotary type surface mounters.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.379-384
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• 1995

In order to construct B-ISDN, it is inevitable to introduce optical fiber of low loss and wide bandwidth. Coincidently, high count optical fiber cable is solely important to form optical subscriber network. The best structure of high count optical fiber cable to achieve multi-splicing as well as high density at the same time is the one of taking optical ribbon as a unit of accomodation. However, since optical ribbon has its own width. optical loss due to length difference during the bending of ribbon cable unit occurs in relatively easy way. Therefore, care should be taken during its manufacturing and storage. In t\1::; paper, strain, bending radius and lateral pressure of each fiber in ribbon due to the bending of ribbon cable unit are caculated theoretically. Hence, we have measured optical loss of each fiber as function of unit bending radius, when we bent the ribbon cable unit on the various reel. We found that the result accords well with the theoretical analysis. The result shows the importance to determine proper radius of reel used in ribbon cable manufacturing and storage. orage.

• Fire Science and Engineering
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• v.30 no.6
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• pp.1-8
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• 2016

In cars, the amount of combustibles, such as plastics, textiles, etc., have increased dramatically to improve the fuel efficiency of cars by reducing the gross vehicle weight according to the increases in an oil price and to reduce environmental problems. One or two cars were involved in a parking lot fire prior to the mid-2000 s. On the other hand, there were many parking lot fires where the entire car was destroyed due to increasing the use of plastics. In this study, the quantity of combustibles in a car was 316.2 kg over a total weight 1935 kg. This is 16.34% of total weight and 10 times greater than that three decades earlier. When a sprinkler is installed as a parking lot fire protection system as a substitute for water spray, the water discharge of the sprinkler must maintain the original density of water spray, $20lpm/m^2$. In addition, the use of a hose reel $CO_2$ system at pilotis parking lots must be prohibited because the hose reel $CO_2$ system has no adaptability for a car fire. Instead, this study proposes foam, dry powder, loaded stream systems be used in parking lot fire suppression systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.22-23
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• 2005

In order to increase the critical current of coated conductor, highly Bi-axially textured substrates are required. Texture uniformity of substrate is also important to fabricate high quality superconducting coated conductor because the amount of current flow along the coated conductor is limited by the defects such as bad textured area. Therefore, we need to evaluate the distribution of texture of Ni substrate along the length before buffer layer deposition on Ni tape. R2R(reel-to-reel) XRD system was used to measure the texture of long Ni substrate continuously. $\theta-2\theta$ scan of 10 m long Ni tape was measured and indicates that some of Ni(111) planes equally remain on Ni(002) textured substrate. The results of continuous Ni(220) $\Phi$-scan indicate that average FWHM is 9$^{\circ}$ within $\pm$1.

• Progress in Superconductivity
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• v.9 no.1
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• pp.102-106
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• 2007

YBCO films have been synthesized using a spray pyrolysis method. We used nitrates of Y, Ba, Cu as precursors. Deposition was made on $LaAlO_3$ (100) single crystal substrate by spraying the mist of aqueous precursor solution generated by a concentric nozzle. The distance between concentric nozzle and substrate was 15 cm. C-axis oriented films were obtained at deposition temperature of $740{\sim}800^{\circ}C$ and working pressure of 20 Torr. Oxygen partial pressure was 3 Torr and substrate was transported with the speed ranging from 0.23 cm/min to 0.7 cm/min by reel to reel. Scanning electron microscope (SEM) and X-ray diffraction (XRD) observation revealed that films are smooth and highly textured with (001) planes parallel to substrate. Highest critical current density (Jc) was $1.38\;MA/cm^2$ at 77K and self-field for the film with a thickness of $0.5\;{\mu}m$ prepared at a substrate temperature of $780^{\circ}C$ and $PO_2\;=3\;Torr$. The effect of temperature on the microstructure and YBCO phase formation will be discussed.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1841-1843
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• 2005

냉간 압연과 열처리 공정을 통해 2축 배향성을 가지는 금속 기판 위에 산화물 박막을 중착 시켜 같은 정도의 2축 배향성을 갖도록 제조된 RABiTS template 위에 YBCO 초전도체를 PLD 방법으로 증착하여 YBCO coated conductor 선재를 제조하였다. RABiTS template은 $NiW/Y_2O_3/YSZ/CeO_2$ 구조로 DC reactive sputtering와 PLD 방법에 의해 증착되었다. 모든 공정은 reel-to-reel 방식의 연속 공정으로 이루어졌다. 1m와 10m급의 장선 고온초전도선재를 제조하고, 이에 대한 전기적 특성과 초전도 및 다층 산화물 완충층에 대한 결정성, 표면 특성에 대한 분석을 수행하였다. 그 결과 1m 길이에서 end-to-end 107A와 10.6m 길이에서 end-to-end 51A의 임계 전류를 획득하였다. 제조된 박막형 선재의 초전도 층과 다층의 산화물 완충층 모두 금속 기판의 결정성을 그대로 유지하면서, epitaxial하게 성장하였으며, 최종 YBCO의 in-plane FWHM 값은 > $9^{\circ}$를 유지하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.50-51
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• 2005

냉간 압연과 열처리 공정을 통해 2축 배향성을 가지는 금속 기판 위에 산화물 박막을 증착 시켜 같은 정도의 2축 배향성을 갖도록 제조된 RABiTS template 위에 YBCO 초전도체를 PLD 방법으로 증착하여 YBCO coated conductor 선재를 제조하였다. RABiTS template은 NiW/$Y_2O_3$/NSZ/$CeO_2$ 구조로 DC reactive sputtering와 PLD 방법에 의해 증착되었다. 모든 공정은 reel-to-reel 방식의 연속 공정으로 이루어졌다. 1m와 10m급의 장선 고온초전도선재를 제조하고, 이에 대한 전기적 특성과 초전도 및 다층 산화물 완충층에 대한 결정성, 표면 특성에 대한 분석을 수행하였다. 그 결과 1m 길이에서 end-to-end 107 A와 10.6m 길이에서 end-to-end 51A의 임계 전류를 획득하였다. 제조된 박막형 선재의 초전도 층과 다층의 산화물 완충층 모두 금속 기판의 결정성을 그대로 유지하면서, epitaxial하게 성장하였으며, 최종 YBCO의 in-plane FWHM 값은 > $9^{\circ}$를 유지 하였다.

• Journal of the Society of Disaster Information
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• v.15 no.3
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• pp.402-408
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• 2019

Purpose: The study want to verify application the medium expantion foam extinguisher of expantion foam rate and fire extinguishing Performance test because the medium expansion system can maintain the discharge distance less affected by air currents, and the foam agent can be used efficiently. Method: For the study, the medium-expansion testing apparatus was manufactured and with synthetic surfactant foam agent of (class B) fire extinguishing model, and Fire Performance was analyzed for foam expansion rate and the fire agent consumption was measured and analyzed. Results: We measured the medium-spray testing apparatus and found that the expansion rate was 26.1 times. The test results of a 20-unit fire extinguishing model show that the extinguishing time is faster than the high and low foam expansion. It has been analyzed that it is possible to apply a hand-operated with a hose reel or medium expansion apparatus. Conclusion: Considering that the foaming agent and the extinguishing performance of the medium foam ratio are excellent, It is necessary to introduce the technical standards of medium foam agent for the introduction of hand-operated equipment, such as hose reel or portable medium foam apparatus.