• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.629-630
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• 2006

• Journal of the Optical Society of Korea
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• 제6권1호
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• pp.13-17
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• 2002

We demonstrated 1.28-Tb/s (64 ch $\times$ 20 Gb/s) WDM transmission with 50-GHz channel spacing over 320 km of conventional single mode fibers. The spectral efficiency was 0.4 (bit/s)/Hz. Thus, we could accommodate all the sixty-four WDM channels within the C-band of EDFA The average Q-factor was measured to be better than 17.8 dB after transmission over 320 km.

• Journal of the Korean Society for Nondestructive Testing
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• 제25권6호
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• pp.446-450
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• 2005

We have built a spherically focused, not using acoustic mirrors, capacitive micromachined air-coupled ultrasonic transducer. A flexible backplate of a copper/polyimide backplate is used, permitting it to conform to a spherically shaped substrate. The backplate is patterned with $40-{\mu}m$ depressions having $80-{\mu}m$ center-to-center spacing. A $6-{\mu}m$ thick aluminized Mylar film completing the transducer is deformed to allow it to conform to the spherical backplate. The device's frequency spectrum is centered at 805kHz with -6dB points at 440 and 1210kHz.

• Carbon letters
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• 제2권2호
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• pp.99-104
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• 2001

Partial mesophase (PM) pitch precursor was prepared from fluidized catalytic cracking-decant oils (FCC-DO) by chemical reaction in the presence of $Br_2$. The PM pitch heated-treatment at $420^{\circ}C$ for 9 h exhibited the softening point of $297^{\circ}C$ with 23% yield, and 55% anisotropic content. The PM pitch precursor was melt-spun through circular nozzle by pressurized $N_2$, stabilized at $310^{\circ}C$, carbonized at $700^{\circ}C$, $1000^{\circ}C$, and $1200^{\circ}C$. The enough stabilization introduced 16.4% of the oxygen approximately. The stacking height ($L_{c002}$) and interlayer spacing ($d_{002}$) of the as-spun fibers were 4.58 nm and $3.45{\AA}$ and the value became minimum and maximum at $700^{\circ}C$ respectively in the carbonization procedure. The tensile strength increased with an increase in the heat treatment temperature exhibiting highest value of 750 MPa at $1200^{\circ}C$ carbonization.

• Proceedings of the KIEE Conference
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.468-469
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• 2008

In this paper, the effects of earth continuity conductor are deeply analyzed for reducing the level of induced sheath voltage at the single point bonded sections. The various installation conditions of an earth continuity conductor are considered including conductor dimensions, its spacing from the three phase cables, and utilization of two earth continuity conductors when the grounding fault occurs on real power cable systems. Finally, the transient characteristics including reduction effects of induced sheath voltage are proved by EMTP simulations. The optimal installation condition of earth continuity conductor is also proposed based on those results.

• Fashion & Textile Research Journal
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• 제11권3호
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• pp.481-487
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• 2009

The purpose of this study is to improve the defects of dyeable polypropylene(DPP) fabric by heat setting and to describe the change of physical properties of DPP fabrics. The thermosetting was carried out in autoclave from 100 to $140^{\circ}C$ temperature range for 2 min. In this study, we investigated the effect of the thermosetting temperatures on the structural, thermal, mechanical properties(e.g., the strength and elongation) and dyeability of DPP fabrics. The melting energy(J/g), the tensile strength was found to increase with increasing temperature of thermosetting. The diffraction peak at Bragg angle($2{\theta}$) about $13.8^{\circ}$ were very strong and diffraction intensity increased with increasing thermosetting temperatures. And d-spacing and half-width decreased with increasing thermosetting temperatures. On the other hand, the dyeability(K/S) and crease recovery decreased with an increasing thermosetting temperatures.

• Journal of applied mathematics & informatics
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• 제18권1_2호
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• pp.171-182
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• 2005

An analysis of the non-homogeneous term involved in the free surface condition for second order wave diffraction on a pair of cylinders is presented. In the computations of the nonlinear loads on offshore structures, the most challenging task is the computation of the free surface integral. The main contribution to this integrand is due to the non-homogeneous term present in the free surface condition for second order scattered potential. In this paper, the free surface condition for the second order scattered potential is derived. Under the assumption of large spacing between the two cylinders, waves scattered by one cylinder may be replaced in the vicinity of the other cylinder by equivalent plane waves together with non-planner correction terms. Then solving a complex matrix equation, the first order scattered potential is derived and since the free surface term for second order scattered potential can be expressed in terms of the first order potentials, the free surface term can be obtained using the knowledge of first order potentials only.

• Economic and Environmental Geology
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• 제32권2호
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• pp.161-167
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• 1999

Electric and electromagnetic surveys were conducted to investigate the deep structure of the Ulsan fault in Ipsil area, south of Kyeongju. On this study, especially high-frequency magnetotelluric method of electromagnetic survey in the frequency range of 10~100,000 Hz was mainly employed to study the deep subsurface configuration. High-frequency MT survey was performed at 70 points of spacing 30~50 m, making 3.8 km survey line. As a survey result, a 2-km-depth 2-D cross-section was achieved. It shows vertical and horizontal subsurface variations of resistivity values. Near-surface layer having low resistivity value becomes thicker eastward up to 800m. There is a steep low resistivity zone in the west side of survey line, and there exists two low resistivity zones dipping west in the east side of survey line. Two low resistivity zones are interpreted to be related to major movement pattern of the Ulsan fault. This suggests that major fault lines are developed on both peripheral sides of the broad fault zone.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제20권11호
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• pp.1064-1070
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• 2010

In this work, a dynamic absorber with a plate-type cantilever using magnetic force is proposed to reduce the vibration of a compressor directly. The dynamic absorber using magnetic force has some advantages of easily tuning the control frequency by adjusting the magnet spacing and obtaining wider control frequency band. The dynamic absorber is designed theoretically and tested experimentally to estimate the control frequency band. When the compressor is equipped with the dynamic absorber, the vibration of compressor and the noise level of refrigerator are reduced by 30 % and 3.2 dB respectively.

• Journal of the Korean Solar Energy Society
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• 제22권2호
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• pp.1-10
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• 2002

This study is a study on the building integrated method of Photovoltaic. It was analyzed into a basic installation condition and an integrated form in this study. And it was confirmed through the 3D simulation & drawing work of an integrated situation to the real domestic building. The Photovoltaic installation of the country to an optimal efficiency for the year must be installed to the due south with an angle of thirty degrees. And also a module spacing must be more than doubled from the bottom to the top of module to prevent from efficiency falling by a shadow of photovoltaic module in a roof setting of flat roof. If Photovoltaic module is an adequate material that is a basic requirement as a building's finishing material, it's not only an efficiency of alternation with an existing finishing material but also a building's design element.