• 한국광학회지
• /
• 제19권3호
• /
• pp.169-174
• /
• 2008

열처리에 의한 광섬유 코어의 모드 확산과 모드 진화 현상을 이용하여 일반 통신용 단일모드 광섬유와 하이텔타(high ${\Delta}$) 광섬유 사이의 접속 손실을 줄일 수 있는 기법들을 제시하였다. 실험결과는 하이텔타 광섬유의 적절한 열처리를 통해 기계적 접속 손실이 2.3 dB에서 0.1 dB까지 감소함을 나타내었다. 반면 융착접속 후 접속 부위에 전기 방전이나 산소 불꽃으로 열을 인가하는 방법으로 $0.2{\sim}0.4dB$ 정도의 접속 손실을 달성하였다.

• Geomechanics and Engineering
• /
• 제28권1호
• /
• pp.77-87
• /
• 2022

Many geotechnical analyses require the investigation of water flow within partially saturated soil zone to incorporate the effect of climatic conditions. It is widely understood that the hydraulic properties of the partially saturated soil should be included in the transient seepage analyses. However, the characteristics of dual porosity soils with dual-mode water retention curve are normally modelled using single-mode mathematical equation for simplification of the analysis. In reality, the rainwater flow can be affected significantly by the dual-mode hydraulic properties of the soil. This paper presents the variations of safety factor for dual porosity soil slope with dual-mode water retention curve and dual-mode unsaturated permeability. This paper includes the development of the new dual-mode unsaturated permeability to represent the characteristics of soil with the dual-mode water retention curve. The finite element analyses were conducted to examine the role of dual-mode water retention curve and dual-mode unsaturated permeability on the variations of safety factor under rainfall loading. The results indicate that the safety factor variations of dual porosity soil slope modelled using the dual-mode water retention curve and the unsaturated permeability equation are lower than those of dual porosity slope modelled using single-mode water retention curve and unsaturated permeability equations.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.620-622
• /
• 2009

We demonstrated a liquid crystal display (LCD) mode with a single polarizer based on the array of a switchable microlens consisting of a circular stop mask and its complementary open mask. The focused beam passed through the open mask and thus the bright state was obtained, while the defocused beam was blocked by the stop mask and the complementary open mask. It is expected that our single-polarizer LCD mode is applicable to low cost displays.

• 전력전자학회논문지
• /
• 제25권5호
• /
• pp.343-349
• /
• 2020

This study proposes a new single inductor converter for DC grid systems. A conventional system is composed of two independent converters for controlling battery and load. This system is simple but it has two inductors that affect power density and efficiency. The proposed converter can reduce the number of inductors by integrating the two converters and relieve voltage stress on switches by using a battery switching cell. Accordingly, power density and efficiency can be improved using a single inductor and lower voltage-rated switches. A prototype of a 500 W converter is built, and each mode is experimented on to confirm the validity of the proposed converter.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제51권6호
• /
• pp.260-264
• /
• 2002

We developed LD Pumped Nd:$VVO_4$ microchip laser with the cavity length of 1mm. The microchip laser output was 87.5㎽ at the wavelength of 1063.9nm with the input power of 241㎽ at the wavelength of 809nm. The slope efficiency was 40.7% and the threshold input power was 31.1㎽. We have also defined input power limit for the single longitudinal mode operation theoretically. It was 2.5 times larger than that of threshold input intensity. According to the results of simulation, the Nd:YVO$_4$ microchip laser can be operated with the maximum output of 15㎽ for the single longitudinal mode up to the input power of 77.75㎽.

• 대한기계학회논문집A
• /
• 제38권2호
• /
• pp.105-113
• /
• 2014

중앙에 균열을 갖는 단층 그래핀시트(single layer graphene sheet, SLGS)의 모드 II 파괴 거동을 원자 시뮬레이션과 해석 모델에 기초하여 고찰하였다. 지그재그 그래핀 모델의 파괴를 분자동역학(molecular dynamics, MD)에 의해 해석한 결과 모드 II 파괴인성은 $2.04MPa{\sqrt{m}}$인 것으로 밝혀졌다. 또한 SLGS의 이론적인 $K_{IIc}$를 유도하기 위해 면내전단하중을 받는 다공체에 대한 파괴역학적 해석도 진행하였고 유한요소해석도 병행하였다. 모드 I과 모드 II의 비를 다양하게 변화시켜가면서 SLGS 의 혼합모드 파괴를 검토한 결과 혼합모드 파괴조건식이 얻어졌고 다른 문헌의 결과와 비슷함을 알 수 있었다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 추계학술대회논문집
• /
• pp.310-313
• /
• 2005

This paper is concerned with the active vibration control of beam equipped with piezoceramic sensors and actuators. The single-input and single-output positive position feedback controller is considered as an active vibration controller for the beam. The proposed single-input and single-output positive position feedback controller can cope with many modes of interest by summing each positive position feedback controller designed for each mode. In this paper, theoretical formulation is first explained in detail. We discuss how to design the single-input and single-output positive position feedback controller for a target structure by considering Euler-Bemoulli beam. It is found that the theories developed in this study are capable of predicting the control system characteristics and its performance.

• 전자공학회논문지D
• /
• 제34D권11호
• /
• pp.48-53
• /
• 1997

Volume hologram was recorded using reference beam form optical fiber taper. A singel mode fiber was chemically etced to make a taper structure, and we showed experimentally that the referencing by the irregular beam pattern from this taper structure could increase the storage density of photorefractive volume hologram. The spatial selectivity of the volume hologram with this method was increased by two times compared to the normal single mode fiber referencing case. A theoretical analysis with randomly phased plane model also confirmed the results.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2007년도 하계학술발표회 논문집
• /
• pp.35-36
• /
• 2007

We report a probe using a single double clad fiber (DCF) for fluorescence spectroscopy. Bidirectional separate transmission for excitation and fluorescence light in a single fiber was implemented. A DCF coupler made by side-polished method could extract none but the collected fluorescence signals propagating in inner cladding mode, thereby diminishing the interference of silica background generated by the excitation in core mode. The experimental results show that the fluorescence spectra of biological tissues obtained using the DCF probes have much less silica background than using a standard multiple-mode fiber.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2008년도 하계학술발표회 논문집
• /
• pp.139-140
• /
• 2008

We demonstrate a novel acousto-optic filter using a two-mode photonic crystal fiber. Thanks to endless two-mode operation of the fiber, single notch over a whole spectrum is obtained with tuning range of> 1000 nm.