Dispersion-Managed Link Configured with Repetitively Shaped Dispersion Maps and Embedded with Mid-span Spectral Inversion

정재필,이성렬 한국정보통신학회 2022 Journal of information and communication convergen Vol.20 No.4

A dispersion map was proposed to improve the compensation effect of a distorted WDM (wavelength division multiplexed) channel in a dispersion-managed link coupled with optical phase conjugation. The dispersion map is an origin-symmetric structure around the optical phase conjugator in the middle of the transmission path. In addition, the dispersion map has a form in which a constant dispersion accumulation pattern is repeated regularly. Through simulation, we confirmed that the application of the origin-symmetric dispersion map with a repetitively shaped configuration was more effective in compensating for the distorted WDM channel than in the dispersion-managed link with a conventional dispersion map. In addition, we confirmed that the compensation effect could be increased when the cumulative dispersion distribution of the origin-symmetric distribution map had a positive value in the first half section and a negative value in the second half section. Further, we observed that as the number of repeated dispersion accumulation patterns increased, the residual dispersion per span should also be increased.

SMF와 DCF의 길이와 분산 계수가 불규칙하게 분포하는 분산 제어 링크

이성렬 한국항행학회 2018 韓國航行學會論文誌 Vol.22 No.3

A flexible dispersion-managed link configuration is proposed by using single-mode fibers (SMFs) and dispersion-compensating fibers (DCFs) with irregular dispersion coefficients and lengths over all fiber spans for compensating of WDM channels distortion due to the group velocity dispersion and nonlinear effects of optical fibers. The flexibility of link is enabled by artificially distributing of these fibers based on the dispersion coefficients of DCFs in each half transmission section. The simultaneous ascending and descending (AD) distribution of the DCF’s coefficients before and after the optical phase conjugator, respectively, best compensates the distorted wavelength division multiplexed signals in the optical link. Therefore, to improve the compensation effect of the distorted WDM channels, AD distribution is needed to choice regardless of fiber lengths and the residual dispersion per span and fiber’s dispersion coefficients. 전체 광 중계 구간 모두 불규칙한 분산 계수를 갖는 단일 모드 광섬유와 분산 보상 광섬유 (DCF; dispersion compensating fiber)를 이용한 융통적인 분산 제어 링크 구조를 제안하였다. 링크의 융통적 구성은 각 전송 반 구획에서 DCF의 분산 계수를 기준으로 이들을 인위적으로 분포시켜서 가능하게 하였다. 광 위상 공액기 전의 전송 반 구획에서는 DCF의 분산 계수를 점진적으로 증가시키고, 광 위상 공액기 다음의 전송 반 구획에서는 DCF의 분산 계수를 점진적으로 감소시키는 ‘AD’ 분포에서 왜곡된 파장 분할 다중 (WDM; wavelength division multiplexed) 신호가 최상으로 보상되는 것을 확인하였다. 따라서 왜곡된 WDM 채널의 보상 효과를 더욱 증가시키기 위해서는 광섬유의 길이, 중계 구간 당 잉여 분산뿐만 아니라 광섬유의 분산 계수에 상관없이 ‘AD’ 분포를 선택할 필요가 있다는 것을 확인하였다.

이득과 분산을 조절한 광섬유의 변조 불안정성 분석

최병훈,김상인,Choi, Byung-Hoon,Kim, Sang-In 한국광학회 2007 한국광학회지 Vol.18 No.2

본 논문에서는 주기적으로 분산 값의 부호가 바뀌는(dispersion managed: DM) 선로에서 급작스런 분산 변화로 인한 scattering을 완화시키도록 이득을 공간적으로 변조(gain management: GM)하는 시스템을 제안하고 이에 대한 modulation instability(MI) 변화에 대한 이론적인 분석과 수치해석적인 분석을 보고한다. 연구결과 어떤 경우에도 GM을 가한 시스템이 DM만을 한 시스템 보다 MI 이득의 크기와 cutoff frequency, side band peak모두가 작아짐을 확인하였다. 동일한 광신호 세기에 대해서 MI 이득이 작아지는 것은 four wave mixing 등 광섬유의 비선형 현상을 완화시킴으로써 파장분할다중화 전송의 품질 향상에 도움이 될 뿐 아니라, 솔리톤(soliton)을 이용한 전송에 있어서 하나의 펄스에 더 많은 에너지를 갖게 함으로써 신호대 잡음비를 개선할 수 있음을 의미한다. 본 논문에서는 분산과 이득이 동시에 조절된 선로의 효과를 솔리톤 전송 시스템의 개선된 특성을 편광모드분산(polarization mode dispersion: PMD)가 존재하는 선로에서의 펄스 폭 증가를 통하여 살펴본다. We investigated analytically and numerically the occurrence of modulation instability in fibers with periodic changes both in dispersion and gain. Previously, it has been known that the modulation instability is suppressed in dispersion managed solitons where dispersion is managed in such a way that the local dispersion alternates between the normal and the anomalous regimes. In this work, we enhanced the advantage of the dispersion management scheme by additionally introducing proper gain/loss profiles in fibers. The gain/loss profile is given by $\Gamma(z)=0.5/D(z)*(dD/dz)$, where D(z) represents the dispersion profile. The fundamental gain spectra of the modulation instability in the dispersion and gain managed fibers have been derived analytically and confirmed by numerical calculation. Our investigation reveals that in the dispersion and gain fibers the modulation instabilities are always much more suppressed compared to the case with only dispersion managed. In practical dispersion management schemes, dispersion profiles show discontinuity. and thus. the corresponding gain/loss profiles tend to be finite. In these cases, the gain/loss profiles were approximated by lumped gains/losses of finite values. Our numerical calculations confirm that this approximation also works well.

보상 격차에 대한 연구동향 리뷰 : 개념, 효과, 방법론을 중심으로 향후 연구 제언

김용근,천장현,김영상 한국생산성학회 2020 生産性論集 Vol.34 No.3

Over the past decade, scholars have paid attention to the effect of pay dispersion on individual, team, and organizational outcomes. To fully understand the nature and effect of pay dispersion, we provide a comprehensive and critical review on pay dispersion research. We begin with an overview of theoretical definitions and perspectives of pay dispersion. Pay dispersion is defined as variation of pay level between individuals in an organization. More specifically, pay dispersion can be categorized into vertical and horizontal pay dispersion: vertical pay dispersion is referred to as differences in pay level across jobs or hierarchical level, while horizontal pay dispersion indicates differences in pay level within jobs or organizational levels. We collected pay dispersion studies from domestic journals and international journals in Financial Times Top 50 and review theoretical and empirical evidence. Based on our review, we found that research on pay dispersion mainly used two theoretical perspective: tournament theory and equity theory. Tournament theory suggests that more pay dispersion can enhance effort levels of employees because the wide variation of pay facilitates greater employees' effort and competition. In addition, this theory also argues that pay dispersion can facilitate the employee sorting, in which winners stay and losers leave their organizations. Hence, based on this theoretical perspective, pay dispersion may produce positive impact on organizational outcomes. However, based on equity theory, wide pay dispersion reduces pay equity perception, which negates employees' motivation and commitment, and thus may generate negative organizational outcomes. In the empirical studies we collected, we identified mixed results for the relationship between pay dispersion and organizational outcome variables. For example, it is not clear whether pay dispersion generates positive or negative organizational outcomes. Although some studies have explained the mixed effects based on different types of pay dispersion (vertical or horizontal pay dispersion), the classification also does not clearly uncover the clear effects of pay dispersion on organizational performance. To move forward, we provide future research directions to enrich pay dispersion literature. First, we suggest that pay dispersion research should examine potential mediators and antecedents of pay dispersion. In particular, exploring the mediators can help identifying why pay dispersion positively or negative influences organizational functioning. In addition, the examination for antecedents of pay dispersion is the neglected area of pay dispersion research, and thus future researchers need to investigate the potential antecedents in team or organizational context. Second, research on pay dispersion needs to verify the effect of pay dispersion across different countries or cultural values or in different job categories and at the team level, which may be helpful for identifying why the mixed results occur. Finally, we suggest to use more rigorous measures of pay dispersion to verify the clear effect of pay dispersion in Korean context.

Comparison of three different types of cilostazol-loaded solid dispersion: Physicochemical characterization and pharmacokinetics in rats

Mustapha, Omer,Kim, Kyung Soo,Shafique, Shumaila,Kim, Dong Shik,Jin, Sung Giu,Seo, Youn Gee,Youn, Yu Seok,Oh, Kyung Taek,Yong, Chul Soon,Kim, Jong Oh,Choi, Han-Gon Elsevier 2017 Colloids and surfaces Biointerfaces Vol.154 No.-

<P><B>Abstract</B></P> <P>The aim of this research was to compare three different types of cilostazol-loaded solid dispersion system including solvent-evaporated, solvent-wetted and surface-attached solid dispersion. The effect of polymers and surfactants on the aqueous solubility of cilostazol was investigated, leading to the selection of polyvinylpyrrolidone (PVP) and sodium lauryl sulphate (SLS). Employing a spray-drying technique, numerous surface-attached, solvent-evaporated and solvent-wetted solid dispersions were prepared with various amounts PVP and SLS using water, 90% ethanol and acetone, respectively. Their physicochemical properties, solubility, dissolution and oral bioavailability in rats were assessed compared to the drug powder. Among each solid dispersion system tested, the surface-attached, solvent-evaporated and solvent-wetted solid dispersions composed of cilostazol, PVP and SLS at weight ratios of 3.0 : 0.75 : 1.5, 3.0 : 3.0 : 1.5 and 3.0 : 3.0 : 1.5, respectively, provided the highest drug solubility and dissolution. The solvent-evaporated solid dispersion gave homogeneous and very small spherical particles, in which the drug was changed to an amorphous state. In the solvent-wetted solid dispersion, the amorphous drug was attached to the polymer surface. Conversely, in the surface-attached solid dispersion, the carriers were adhered onto the surface of the unchanged crystalline drug. The solubility, dissolution and oral bioavailability were significantly increased in the order of solvent-evaporated>solvent-wetted>surface-attached>drug powder. Thus, the type of solid dispersion considerably affected the physicochemical properties, aqueous solubility and oral bioavailability. Furthermore, the cilostazol-loaded solvent-evaporated solid dispersion with the highest oral bioavailability would be actively recommended as a practical oral pharmaceutical product.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cilostazol-loaded three different types of cilostazol-loaded solid dispersions were prepared. </LI> <LI> They were prepared with PVP, sodium laurylsulfate and different solvents using spray-drying techniques. </LI> <LI> The solvent-evaporated solid dispersion gave higher drug solubility and bioavailability than the others. </LI> <LI> These different types affected the physicochemical properties and oral bioavailability. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

수직적 임금분산과 이직의도 간의 관계: 직급단계 및 수평적 임금분산의 조절효과

김재엽(Kim Jae-yeoup),최장호(Choi Jang-ho) 한국인사조직학회 2018 한국인사ㆍ조직학회 발표논문집 Vol.2017 No.3

임금분산은 개인의 성과, 직무만족, 이직과 매우 밀접한 관련이 있으므로, 이에 대한 연구는 학술적·실무적으로 매우 중요하다. 본 논문의 목적은 학술적으로 첫째, 임금분산 을 수직적·수평적 임금분산으로 구분하여 연구의 정교함을 향상시키고, 둘째, 이전 연구에서 미진하게 수행한 미시적 차원의 연구를 진행하고, 셋째, 수직적 임금분산과 이직 의도를 기대이론과 토너먼트 이론으로 설명하고 검증하는 것이며, 마지막으로 수직적 임금분산과 직급단계 및 수평적 임금분산과의 상호작용 모델을 개발하고 검증하는 것이다. 특히, 본 논문에서는 이전의 연구흐름과 달리 조직수준의 임금분산, 직급단계가 개인수준의 이직의도에 어떠한 영향을 미치는지를 검증하여 통계적 정교성을 향상시키고자 노력하였다. 다수준 분석 결과, 수직적 임금분산은 이직의도와 부적 관계가 있다는 결과가 도출되었다. 따라서 사원급의 총급여와 부장급의 총급여의 배율이 큰 임금구조는 종업원들에게 임금의 유의성을 제공하여 결과적으로 이직의도를 감소시키는 것으로 이해할 수 있다. 다음으로 직급단계의 조절효과를 분석하였다. 수직적 임금분산, 직급단계(역수)는 이직의도와 직접적으로 영향을 미치는 것으로 확인되었으며, 수직적 임금분산과 직급단계(역수)의 상호작용항은 이직의도와 부적으로 조절하는 결과를 나타내었다. 마지막으로 수직적 임금분산과 수평적 임금분산 간의 임금구조 간의 상호작용 효과는 이직의도와 유의한 관계를 나타내지 못하였다. 이와 같은 연구결과를 바탕으로 시사점 및 향후연구 과제를 도출하고 있다. Since pay dispersion is very closely related to performance, job satisfaction, and turnover, research on pay dispersion is very important both academically and practically. The purpose of this paper is to improve the sophistication of the research by dividing the pay dispersion into the vertical and horizontal pay dispersion, second, to carry out the micro study which was carried out in the previous research, and third, And the intention of turnover with the expectation theory and the tournament theory, and fourth, to develop and verify the interaction model between the vertical pay dispersion and job grade and horizontal pay dispersion. As a result of the multi-level analysis, vertical pay dispersion has a negative relation with turnover. Vertical pay dispersion and job grade(reciprocal) were directly influenced by turnover intention, and the interaction term between vertical pay dispersion and job grade(reciprocal) showed the result of reduction for turnover intention. Finally, the interaction effect between pay structure of vertical and horizontal pay dispersion did not show significant relationship with turnover intention. The results of this study suggest that it is necessary to consider the expansion of vertical pay dispersion and to reduce the job grade in order to lower the employee s turnover intention in the actual pay design.

Near-elliptic Core Triangular-lattice and Square-lattice PCFs: A Comparison of Birefringence, Cut-off and GVD Characteristics Towards Fiber Device Application

Partha Sona Maji,Partha Roy Chaudhuri 한국광학회 2014 Current Optics and Photonics Vol.18 No.3

In this work, we report detailed numerical analysis of the near-elliptic core index-guiding triangularlattice and square-lattice photonic crystal fiber (PCFs); where we numerically characterize the birefringence, single mode, cut-off behavior and group velocity dispersion and effective area properties. By varying geometry and examining the modal field profile we find that for the same relative values of d/, triangular-lattice PCFs show higher birefringence whereas the square-lattice PCFs show a wider range of single-mode operation. Square-lattice PCF was found to be endlessly single-mode for higher air-filling fraction (d/). Dispersion comparison between the two structures reveal that we need smaller lengths of triangular-lattice PCF for dispersion compensation whereas PCFs with square-lattice with nearer relative dispersion slope (RDS) can better compensate the broadband dispersion. Square-lattice PCFs show zero dispersion wavelength (ZDW) red-shifted, making it preferable for mid-IR supercontinuum generation (SCG) with highly non-linear chalcogenide material. Square-lattice PCFs show higher dispersion slope that leads to compression of the broadband, thus accumulating more power in the pulse. On the other hand, triangular-lattice PCF with flat dispersion profile can generate broader SCG. Square-lattice PCF with low Group Velocity Dispersion (GVD) at the anomalous dispersion corresponds to higher dispersion length (LD) and higher degree of solitonic interaction. The effective area of square-lattice PCF is always greater than its triangular-lattice counterpart making it better suited for high power applications. We have also performed a comparison of the dispersion properties of between the symmetric-core and asymmetric-core triangular-lattice PCF. While we need smaller length of symmetric-core PCF for dispersion compensation, broadband dispersion compensation can be performed with asymmetric-core PCF. Mid-Infrared (IR) SCG can be better performed with asymmetric core PCF with compressed and high power pulse, while wider range of SCG can be performed with symmetric core PCF. Thus, this study will be extremely useful for designing/realizing fiber towards a custom application around these characteristics.

임금격차와 근로시간이 종업원의 태도에 미치는 영향

류성민(Seongmin Ryu) 대한경영학회 2017 大韓經營學會誌 Vol.30 No.5

랜덤-반전 분산 맵으로 설계된 분산 제어 링크를 갖는 MSSI 시스템

이성렬 ( Seong-real Lee ) 한국항행학회 2023 韓國航行學會論文誌 Vol.27 No.4

파장 분할 다중 신호와 같은 대용량 광 신호를 장거리 전송하기 위하여 사용되는 MSSI (mid-span spectral inversion)와 분산 제어가 결합된 시스템에서의 융통적인 링크 구성을 제안하고 색 분산과 비선형 왜곡 보상 효과를 높일 수 있는 구체적 방법을 살펴보았다. 분산 제어 링크 구성의 융통성을 높이기 위해 제안된 분산 맵은 ‘random-inverse’ 구조를 갖는다. 즉 광 위상 공액기까지의 전반 구획의 각 광성유 스팬의 RDPS는 랜덤하게 분포되고 후반 구획의 RDPS 분포는 전반 구획의 분포 패턴을 반전하는 구성의 분산 맵이다. 제안된 분산 맵은 RDPS의 랜덤 분포를 가지기는 하지만 결과적으로 광 위상 공액기를 중심으로 분산 프로파일이 대칭이 되는 점에 기인하여 왜곡 보상 효과가 개선되는 것을 확인하였다. ‘random-inverse’ 구조의 분산 맵에서 각 광섬유 스팬에 할당되는 RDPS의 크기가 큰 경우에서 왜곡된 파장 분할 다중 신호의 보상 효과가 더욱 커지는 것도 동시에 확인하였다. We proposed a flexible link configuration in a system combining mid-span spectral inversion (MSSI) and dispersion management used for long-distance transmission of high-capacity optical signals such as wavelength division multiplexing signals, and examined specific methods to increase chromatic dispersion and nonlinear distortion compensation effects. The dispersion map proposed to increase the flexibility of dispersion-managed link configuration has a 'random-inverse' structure. That is, in the proposed dispersion map, the residual dispersion per span (RDPS) of each fiber span in the first half section up to the optical phase conjugator is randomly distributed, and the RDPS distribution in the second half section reverses the distribution pattern of the first section. Although the proposed dispersion map has a random distribution of RDPS, it was confirmed that the distortion compensation effect is improved due to the fact that the dispersion profile is symmetrical with respect to the optical phase conjugator. In the dispersion map of the 'random-inverse' configuration, it was also confirmed that the compensation effect of the distorted wavelength division multiplexing signal becomes improved when the magnitude of the RDPS allocated to each fiber span is large.

Dispersion-managed Optical Link Configured Antipodalsymmetric Dispersion Maps with Respect to Midway Optical Phase Conjugator

Jae-Pil Chung,Seong-Real Lee The Korea Institute of Information and Commucation 2023 Journal of information and communication convergen Vol.21 No.2

We investigated the antipodal-symmetric dispersion maps of a dispersion-managed link with a midway optical phase conjugator to compensate for the distorted 960 Gb/s wavelength division multiplexed (WDM) signal caused by these effects. The proposed antipodal-symmetric dispersion map has various shapes depending on the detailed design scheme. We confirmed that the dispersion-managed link designed with the dispersion map of the antipodal-symmetric structure is more advantageous than the conventional uniform dispersion map for compensating WDM channels. It was also confirmed that among the antipodal-symmetric structures, the dispersion map configured with the S-1-profile, in which S is inverted up and down, was more effective for distortion compensation than the dispersion map configured with the S-profile. In particular, we confirmed that the S-1-profile can broaden the optical pulse width intensively at a short transmission distance, more effectively compensating for the distorted WDM channel. Because this structure makes the intensity of the optical pulse relatively weak, it can decrease the nonlinear Kerr effect.