• Journal of information and communication convergence engineering
• /
• 제5권4호
• /
• pp.377-381
• /
• 2007

Nonlinear effects and chromatic dispersion are the main causes of pulse degradation in high bit-rate WDM transmission systems and several architectures have been proposed to compensate them by means of optical phase conjugation. In this paper, a new method to exploit an optical phase conjugator (OPC) for nonlinearity and dispersion cancellation is disclosed. The proposed method is using optimal total dispersion of each fiber sections and it is simpler than those previously described in literature. Power penalty between WDM channels and the maximum launch power in $28{\times}40$ Gbps WDM transmission system designed by optimal total dispersion are more decreased and more increased than those in the conventional WDM transmission system with OPC, respectively. Furthermore, optimal total dispersion proposed in this research should provide the flexible design of WDM system, which less depends on OPC position.

• Journal of information and communication convergence engineering
• /
• 제12권2호
• /
• pp.75-82
• /
• 2014

Dispersion management (DM), optical phase conjugation (OPC), and the combination of DM and OPC are promising techniques to compensate for optical signal distortion due to group velocity dispersion and nonlinear Kerr effects. The system performance improvement in DM links combined with OPC has been reported; however, the fixed residual dispersion per span (RDPS) usually used in these links restricts the flexibility of link configuration. Thus, in this paper, a flexible optical link configuration with artificially distributed single-mode fiber (SMF) lengths and RDPS in the combination of DM and OPC is proposed. Simulation results show that the best artificial distribution pattern is the gradually descending distribution of SMF lengths and the gradually ascending distribution of RDPS, as the number of fiber spans is increased, regardless of the average RDPS, the optimal net residual dispersion, and the dispersion coefficient of the dispersion compensating fiber.

• Journal of information and communication convergence engineering
• /
• 제15권4호
• /
• pp.205-211
• /
• 2017

Combining dispersion-managed optical links with midway optical phase conjugation (OPC) is a possible method of compensating for optical signal distortion due to group velocity dispersion and nonlinear Kerr effects. Although an improvement in the performance of these optical links has been reported, the fixed residual dispersion per span (RDPS) that is typically used restricts the flexibility of link configurations. Thus, in this paper, a flexible dispersion-managed link configuration, comprising artificial distributions of linearly/nonlinearly incremented RDPS, is proposed. Simulations show that a descending distribution of RDPS before the midway OPC, and an ascending distribution of RDPS after the midway OPC, gives the best artificial distribution pattern as the number of fiber spans is increased, regardless of the RDPS incrementation method.

• 한국광학회지
• /
• 제2권1호
• /
• pp.31-35
• /
• 1991

The third-order nonlinear optical susceptibilities of $\beta$-carotene, retinal and retinol have been measured using self-induced ellipse rotation and dc-Kerr effects. The strengths of $\chi$1221(-$\omega$, $\omega$, -$\omega$, $\omega$) and $\chi$1221(-$\omega$, $\omega$, 0, 0) measured by the two different methods are not different each other significantly. And it is observed that the strength of the third order nonlinear optical susceptibility is relatively insensitive to the conformational difference between retinal and retinol. It is also demonstrated that the third order nonlinear optical susceptibility of long-chained organic molecules is dependent upon the number of the double-bonds.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2011년도 추계학술대회
• /
• pp.650-652
• /
• 2011

축적된 분산(dispersion)과 비선형 효과에 의한 광 신호의 왜곡을 보상하기 위해 중계 구간의 잉여 분산 (RDPS; residual dispersion per span)이 랜덤하게 분포하는 분산 제어 (DM; dispersion management)가 적용되고 전체 전송로 중간에 광 위상 공액기 (OPC; optical phase conjugator)를 둔 광전송 링크를 통해 40 Gbps 광 신호를 최상의 성능으로 전송하기 위한 RDPS 랜덤 분포 조건을 도출하였다.

• 한국의류학회지
• /
• 제26권8호
• /
• pp.1248-1253
• /
• 2002

Coocus laccae(Laccifer lacca Kerr), usually known as Lac, is a kind of cocoon which is parasitic on the tree around India and China. It contains the laconic acid of red colored dyes and has been used for cosmetic or natural dyeing prior to the introduction of New World cochineal. Nevertheless, the characterization of lac has not been studied, very little informed. The purpose of this study is to examine the effects of dyeing conditions fur Lac extract, such as pH of dye bath, concentration of Lac exact dyeing temperature and time, to find out the optimum conditions. The results were as follow. 1. The highest K/S values of the silk and wool was shown at PH 3 and PH 4. 2. K/S values of the silk came to nearly the adsorption equilibrium state at 40$^{\circ}C$ and the curve of wool showed a dramatic increase with the increase of temperature. 3. Dyed silk and wool fabrics showed good light fastness without using mordants.

• Journal of information and communication convergence engineering
• /
• 제16권2호
• /
• pp.67-71
• /
• 2018

The various techniques to compensate for the signal distortion due to the group velocity dispersion (GVD) and nonlinear Kerr effects of optical fibers in the optical links have been proposed in the literature. We propose a flexible dispersion-managed link configuration consisted of single-mode and dispersion-compensating fibers with irregular dispersion coefficients over all fiber spans, and an optical phase conjugator added midway along the optical links. By distributing the lengths of the single mode fibers, we achieve a flexible optical link. The simultaneous ascending and descending distribution of the single-mode fiber lengths before and after the optical phase conjugator, respectively, best compensates the distorted wavelength division multiplexed signals in the optical link with non-fixed coefficients. Our result is consistent with those of our previous work on fixed coefficients. Therefore, to improve the compensation at any magnitude of dispersion coefficient, we must artificially distribute the lengths of the single-mode fibers into a dispersion-managed link.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
• /
• pp.375-377
• /
• 1998

The magneto-optical properties of Co/Co$_2$TiSn two-phase magnet films were studied. These films show that relatively large Kerr rotations which are -0.4 deg. at the wavelength of 400 nm, compared to that of pure Co. It is conceivable that the magneto-optical effects may be due to both contributions of ferromagnetic Co matrix and ferromagnetic Co$_2$TiSn Heusler alloy precipitate. The perpendicular magnetization curve domonstrates a typical bubble domain hysteresis loop. the saturation magnetization change of the annealed film is less sensitive to temperature in the low temperature region and the Curie temperature of Co$_2$TiSn Heusler alloy precipitate is a little higher in the annealed film. These can be explained by the increase of the number of Co-Co exchange interaction in Heusler alloy structure resulting from the change of chemical ordering by annealing.

• Advances in nano research
• /
• 제11권6호
• /
• pp.581-593
• /
• 2021

This model is proposed to describe the buckling behavior of Carbon Nanotubes (CNTs) embedded in an elastic medium taking into account the combined effects of the magnetic field, the temperature, the nonlocal parameter, the number of walls. Using Eringen's nonlocal elasticity theory, thin cylindrical shell theory and Van der Waal force (VdW) interactions, we develop a system of partial differential equations governing the buckling response of CNTs embedded on Winkler, Pasternak, and Kerr foundations in a thermal-magnetic environment. The pre-buckling stresses are obtained by applying airy's stress function and an adjacent equilibrium criterion. To estimate the nonlocal critical buckling load of CNTs under the simultaneous effects of the magnetic field, the temperature change, and the number of walls, an optimization technique is proposed. Furthermore, analytical formulas are developed to obtain the buckling behavior of SWCNTs embedded in an elastic medium without taking into account the effects of the nonlocal parameter. These formulas take into account VdW interactions between adjacent tubes and the effect of terms involving differences in tube radii generally neglected in the derived expressions of the critical buckling load published in the literature. Most scientific research on modeling the effects of magnetic fields is based on beam theories, this motivation pushes me to develop a cylindrical shell model for studying the effect of the magnetic field on the static behavior of CNTs. The results show that the magnetic field has significant effects on the static behavior of CNTs and can lead to slow buckling. On the other hand, thermal effects reduce the critical buckling load. The findings in this work can help us design of CNTs for various applications (e.g. structural, electrical, mechanical and biological applications) in a thermal and magnetic environment.

• 한국항행학회논문지
• /
• 제18권5호
• /
• pp.455-460
• /
• 2014

장거리 광전송 시스템에서 그룹 속도 분산과 비선형 현상에 의한 왜곡을 보상할 수 있는 분산 제어 (DM; dispersion management)와 광 위상 공액 기술이 결합된 전송 링크의 최적 설계를 위한 성능 분석을 수행하였다. 즉 전체 전송 링크의 중간에 위치한 광위상 공액기 (OPC; optical phase conjugator) 양쪽의 전송 구획에서의 잉여 분산의 상호 관계가 최적 전체 잉여 분산 (NRD; net residual dispersion)에 미치는 영향을 살펴보았다. 시뮬레이션 결과 전반 전송 구획에서의 잉여 분산과 후반 전송 구획에서의 잉여 분산의 차이를 10 ps/nm로 하여 전체 전송 링크의 NRD를 10 ps/nm로 설정하여야 가장 우수한 보상이 이루어진다는 것을 확인하였다.