• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.301-304
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• 2008

The stair joints constructed with prefabricated system are general method doing structure design at hinge. If you regarded joints to come in contact with a flight of stairs and a slope of stairs as hinge, the moment performance of joints is not in the least moment, so as the bending moment of the stair case is increased, the reinforcement increase. Also the use is decreased because increasing the joint damage of the vibration & fatigue load. No less the reason constructed with pin the stair joints because the construction efficiency of field work is useable. Recently, they are considering the construction efficiency, while the semi-rigid detail for bending performance of joints is proposed, but for now they don't reflect the detail. Therefore, we proposed that reflecting the method at design semi-rigid joints. We compared the moment performance with the stair joints designed at the rigid joints, semi-rigid joints and pin joints. The nonlinear behavior of staircase core statically indeterminate structure. The result of research is that a bending stiffness modulus bring to reflect the semi-rigid performance, the performance of the semi-rigid joint is better than pin joints, and that is judged the system better seismic and vibration performance because have excellent ductility more than rigid joint.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.833-840
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• 2008

The time and cost can be reduced when applying partial precast concrete to the stair system in comparison to the cast-in-place or precast method. Because the performance of staircase which is used for evacuation can be largely different from connection types of precast concrete member, we tried to know structural behavior and performance evaluation according to each type of stair joints by experimental study. In the cast-in-place rigid joint, much reinforcement is needed in the end portion because much stress is concentrated in the middle portion. Also, in the pin joint which is used in the connection point, the maximum stress occurs in the middle point, so not only the amount of re-bar is increased but also the serviceability is largely decreased. The bolt type of semi-rigid joints proposed in this study had been increased strength and serviceability which is similar to the rigid joints. Also, its ductility was shown about 0.7 times in comparison to the rigid type and was about 2.8 times for the pin joint type. According to the classification of joint in Eurocode, it can be considered that it is one of the semi-rigid joints which are in the semi-rigid-full strength, and the structural behavior can be expected by using a model which applied to stiffness value decreased by 40 percent.

• Land and Housing Review
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• v.2 no.4
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• pp.509-516
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• 2011

Compared with the traditional RC system, precast stairs can save construction time, reduce the cost of concrete casting, etc. This paper focuses on an investigation of improved continuous longitudinal joint details for PC stair systems. The performance of the precast concrete stair connections subjected to displacement control cyclic loading is compared with that of the monolithic connection. The developed connection is composed of U-rods and clamp joint metals. This paper proposes precast stair connection with improved structural performance and experimentally evaluates the structural performance of the proposed joints in terms of maximum load, displacement ductiliy, strain, crack and failure modes.

• Korean Journal of Materials Research
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• v.8 no.10
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• pp.950-955
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• 1998

Ar 이온 식각법을 이용하여 (001) SrTiO3(STO) 단결정 기판 위에 200nm 높이의 계단형 모서리를 제작하였다. 계단식은 입사하는 Ar 이온 빔에 대한 Ar 이온 입사각과 마스크 회전각을 조절함으로써 38$^{\circ}$-70$^{\circ}$의 넓은 범위로 제어할 수 있었다. 초전도 YBa2Cu3O7-$\delta$박막은 계단이 있는 STO 기판 위에 펄스레이저 증착법을 이용하여 증착하였으며, 박막의 두께는 계단 높이에 대한 박막의 두께비가 0.5-1.2가 되도록 하였다. 계단형 모서리 조셉슨 접합의 임계전류밀도와 IcRn값은 77K에서 각각 104A/$\textrm{cm}^2$, 70-200$\mu$V이었다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.3
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• pp.33-39
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• 1983

New Schottky devices with thin stepped oxide layer (about 1000 ${\AA}$) along the edge of metal-semiconductor junction have been designed and fabricated. The breakdown voltages of these diodes have been compared with those of conventional metal overlap and P guard ring Schottky diode structures. Thin stepped oxide layer has been grown by the process of T.C.E. oxidation. In order to compare and demonstrate the improved down phenomena of these devices, conventional metal overlap diode and P guard ring which have the same dimension with new devices have also been integrated in a same New Schottty devices structured with thin stepped oxide layer have shown significant improvement in breakdown phenomena compared with conventional diodes.

• Journal of Korean Society of Steel Construction
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• v.26 no.6
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• pp.511-522
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• 2014

In this study, an innovative steel stair system is presented which enables rapid erection and high quality control in both residential and office building construction. This system features two lightweight steel stringers of box shape, bolted connections easy to absorb construction tolerance, and stair steps movable transversely (or sliding steps) such that the work space needed for concrete stairway wall could be easily provided. In this type of stairway system, other than providing robust connecting details, ensuring vibration performance is especially important since this system may be vibration-sensitive due to lightweight nature and/or probable low damping. To tackle these issues, a series of full-scale mock-up tests were conducted by using box-shape stringer members with or without concrete-fill. The connection system was shown to be sufficiently stiff and strong, or it remained elastic even under the 160% of service load level. Among the seven stringer alternatives, five exhibited satisfactory vibration performance according to the related North American and European acceptance criteria.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1123-1133
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• 1999

In this paper, we applied mode matching and generalized scattering matrix methods to three plane mode matching method for analyzing T-junctions. We calculated all scattering matrix elements by only three times and considered several incident modes. By proposed analysis method, we could analyze various waveguide discontinuity structures more conveniently and accurately. Using the stepped T-junction, we would be able to reduce the reflection coefficient at an input port and use it over wider band. Simulated and HFSS data of T-junctions are compared, showing good agreement for scattering matrix elements. Considering step numbers, height, length and position, we extracted for optimum dimensions and equivalent circuit parameters.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1889-1893
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• 2008

본 연구에서는 완경사 계단형 낙차공에서 하류수심 변화에 따른 도수 형태의 변화와 WTF 흐름 특성에 대한 분석을 수행하였다. 일정한 유량에서 하류수위를 증가시키면 도수 형태가 달라지는데 특히 계단 끝단에서 완전도수, 잠김도수(B점프), downward curved jet, upward curved jet, wave type flow(WTF)가 차례로 나타났다. 잠김도수에서는 표면 롤러 현상이 관찰되었고 curved jet에서는 큰 유속 감세 없이 파가 하류까지 전달되었다. WTF에서는 사류흐름이 바닥 recirculation 구역의 영향으로 변형되면서 wave 형태의 도수를 발생시켰다. 하류수위를 점점 증가 시키면 도수의 발생 위치가 계단 위쪽으로 이동하며 잠김도수와 WTF가 번갈아가며 발생하였다. 하류수위가 높아질수록 도수의 규모는 작아졌으며 표면 롤러도 미약해지는 경향을 보였다. 세 가지 유량조건에 따른 WTF의 규모를 비교한 결과 유량이 증가할수록 WTF의 크기가 증가하였으며 무차원화한 WTF의 형상은 거의 비슷한 것으로 나타났다. 계단형 낙차공은 기존낙차공에서 발생하는 도수와 달리 WTF가 발생되므로 이에 대한 분석이 필요하다. WTF가 발생하는 구간의 수위는 하류수위보다 높아지기 때문에 하천 설계 시 하천 접합부의 조건(구수부지설치, 제방설치 등)에 따라 wave의 높이가 설계의 중요 인자로 고려되어야 할 것이다. WTF는 지금까지의 계단형 낙차공 설계 시 고려되지 못한 부분으로서 차후에 계단형 구조물 또는 계단식 변형 구조물 설계 시 주요 자료로 활용 될 것이다.

• Korean Journal of Materials Research
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• v.9 no.1
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• pp.86-91
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• 1999

We have fabricated high-$\textrm{T}_c$ superconducting $\textrm{YBa}_{2}\textrm{Cu}_{3}\textrm{O}_{7-x}$(YBCO) grain boundary junctions at a step-edge on (001) $\textrm{SrTiO}_3$(STO) substrates. A diamond-like carbon (DLC) film grown by plasma enhanced chemical vapor deposition were used as an ion milling mask to make steps on the STO (100) single crystal and was removed by an oxygen reactive ion etch process. The c-axis oriented YBCO and TO thin films were deposited epitaxially on the STO substrate with a step-edge by pulsed laser deposition. The grain boundary junctions were formed at the top and the bottom of the step. The junctions worked at temperatures above 77 K, and had I\ulcornerR\ulcorner products of 7.5mV at 16K and 0.3 mV at 77K, respectively. The I-V characteristics of these junctions showed the shape of the two noisy resistively shunted junction model.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.9
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• pp.1-9
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• 2004

Analytical expressions for breakdown voltages of abrupt pn junction in GaP, GaAs and InP of III-V binary semiconductors was induced. Getting analytical breakdown voltage, effective ionization coefficients were extracted using ionization coefficient parameters for each materials. The result of analytical breakdown voltages followed by ionization integral agrees well with numerical and experimental results within 10% in error.