A Monte Carlo study of polarization structures in the Thomson-scattered line radiation     

Hyo Jeong Kim  Hee-Won Lee  Suna Kang 《Monthly notices of the Royal Astronomical Society》2007,374(1):187-195

Thomson scattering is often invoked to explain broad wing features that are seen in various objects including active galactic nuclei and symbiotic stars. Despite the wavelength-independent scattering cross-section of Thomson scattering, the line flux may exhibit wavelength-dependent linear degree of polarization, because various parts of emission wings are contributed by photons with different scattering numbers. Specifically, more scattered and hence more weakly polarized photons tend to fill the farther wing parts from the line centre, while the neighbourhood of the line centre is dominated by less-scattered photons with higher degree of polarization. Using a Monte Carlo technique, we investigate the polarization structure of Thomson-scattered line radiation. A detailed analysis of polarization structure formation is conducted by investigating the dependence of the polarization and profile width on the scattering number for various finite electron scattering slabs. Significantly varying degree of polarization is obtained when the scattering medium has Thomson optical depth  τ_Th≥ 1  . We present our high-resolution spectrum of the symbiotic star V1016 Cyg obtained with the Bohyunsan Optical Echelle Spectrograph (BOES) in order to fit the broad profile around Hα by electron scattering wings adopting an oblate spheroidal geometry with Thomson optical depth  τ_Th= 0.5  and electron temperature   T _e= 6.2 × 10⁴  K  . Local maxima in the linear degree of polarization of Thomson-scattered line radiation are expected to appear in the spectral regions characterized by the average scattering number ≃1.  相似文献   

Simulation of tunnel response under spatially varying ground motion     

Duhee Park  Myung Sagong  Dong-Yeop Kwak  Chang-Gyun Jeong 《Soil Dynamics and Earthquake Engineering》2009,29(11-12):1417-1424

Various components including wave scattering, wave passage, and site amplification effects cause the ground motion to vary spatially. The spatially varying ground motion can significantly influence the dynamic response of longitudinal structures such as bridges and tunnels. While its effect on bridges has been extensively studied, there is a lack of study on its effect on underground tunnels. This paper develops a new procedure for simulating the tunnel response under spatially varying ground motion. The procedure utilizes the longitudinal displacement profile, which is developed from spatially variable ground motion time histories. The longitudinal displacement profile is used to perform a series of pseudo-static three-dimensional finite-element analyses. Results of the analyses show that the spatially variable ground motion causes longitudinal bending of the tunnel and can induce substantial axial stress on the tunnel lining. The effect can be significant at boundaries at which the properties of the ground change in the longitudinal direction.  相似文献   

Role of Siliceous Fossil Dissolution in Downcore Variations of Grain Size and Water Content: Western Margin of Clarion-Clipperton Fracture Zone,NE Equatorial Pacific     

Hoi-Soo Jung  Kap-Sik Jeong  Yong-Shik Chu  Sung-Hyun Park  Ki-Hyune Kim 《Marine Georesources & Geotechnology》2013,31(3):181-195

Abstract

Grain size and water content in box-core sediments from the Clarion-Clipperton fracture zone (C-C zone) in the northeast equatorial Pacific were analyzed in detail to understand the downcore variations across a hiatus between Quaternary and Tertiary layers. Grain-size distributions in the topmost core sediments show two modes: a coarse mode (peaked at 50 μm) and a fine mode (at 2–25 μm). The coarse mode disappears gradually with depth accompanied by the dissolution of siliceous fossil tests, whereas the fine mode coarsens due to the formation of authigenic minerals. Water content increases abruptly across a color boundary between an upper pale brown layer and a lower dark brown layer that is the hiatus between Quaternary and Tertiary layers. Abundant smectites and microvoid molds, which are created by the prolonged fossil dissolution in the underlying sediment, are attributed for the abrupt downcore variation of water content. Overall variations in grain size and water content in the topmost core sediments in the western C-C zone are possibly constrained by the dissolution of biogenic siliceous fossils. Variations in geotechnical properties related to these changes must be considered in the design of nodule collectors.  相似文献   

Study of the State and Variability of Marine Environment in the Japan/East Sea in Cruise 58 of the R/V Akademik Oparin     

Lobanov  V. B.  Sergeev  A. F.  Kim  G.  Nam  S.  Maryina  E. N.  Han  H.  Popov  O. S.  Tishchenko  P. P.  Vlasova  G. A.  Zverev  S. A.  Choi  S. J.  Jeong  H.  Kim  B.  Kim  Y.  Kim  S. Y.  Lee  I.  Lee  H.  Lee  H.  Leusov  A. E.  Mariaysh  A. A.  Prushkovskaya  I. A.  Rudykh  Y. N.  Ryu  Y.  Ryumina  A. A.  Sagalaev  S. G.  Semkin  P. Y.  Seo  H.  Shkirnikova  E. M.  Shlyk  N. V.  Shvetsova  M. G.  Tsoi  V.  Ulanova  O. A. 《Oceanology》2021,61(4):586-588

Oceanology - Multiyear monitoring of the marine environment of the Japan/East Sea was continued by the joint Korean–Russian expedition of the R/V Akademik Oparin (cruise 58) in...  相似文献   

Trace metals (Co,Ni, Cu,Cd, and Pb) in the southern East/Japan Sea     

Jeongwon Kang  Man-Sik Choi  Kap-Sik Jeong  Chang-Bok Lee 《Ocean Science Journal》2014,49(1):47-65

Total dissolvable metals (Co, Ni, Cu, Cd, and Pb) in both surface waters and the water columns were acquired in the southern East/Japan Sea during a cruise around the Ulleung Basin in June 2001 to understand the spatial distributions of the metals. Concentrations in offshore surface waters were found to be Co 60 ± 12 pM, Ni 2.16 ± 0.25 nM, Cu 1.85 ± 0.55 nM, Cd 0.134 ± 0.018 nM, and Pb 155 ± 40 pM. Spatial distributions in surface waters showed that metal levels were generally enhanced at coastal sites in both Korea and Japan, where the metal distributions indicated complex patterns due to inputs, biogeochemical processes, and physical factors including upwelling. The Co distributions in the water columns seemed to be influenced predominantly by surface and bottom inputs, scavenged rather than regenerated at depth. For Cd, there was generally good agreement between the Cd and PO₄ depth distributions, in agreement with the literature. The Cd/PO₄ ratio from the water columns was found to be 0.133–0.203, lower than that in other marginal seas (e.g. the East/South China Seas and the Philippine Sea) of the western Pacific Ocean; this might be a result of the fast ventilation rate in this sea. The vertical Pb profile showed typical scavenged-type behavior with a surface maximum and deep minimum. From a comparison of inputs from the atmosphere and the Tsushima Warm Current, atmospheric deposition is substantial enough that it cannot be ignored, and its role in metal cycling is more significant in the offshore zone.  相似文献   

Toxicological impact assessment of heavy metal contamination on macrobenthic communities in southern coastal sediments of Korea     

Dhong-il Lim  Jin-Woo Choi  Hyeon Ho Shin  Do Hyun Jeong  Hoi Soo Jung 《Marine pollution bulletin》2013

In the heavily industrialized Masan Bay of southern coast, Korea, the potential harmful effects of heavy metals (Cd, Co, Cu, Ni, Pb, Sn, Zn, and Hg) were evaluated in terms of the pollution load index (PLI) and ecological risk assessment index (ERI) methods, and the results obtained were considered alongside the health of the macrobenthic fauna communities. The results revealed that the bay sediments, especially in the inner bay and the outfall area of a sewage treatment plant, are exposed to moderate to serious levels of metal pollution. Hg and Cd contributed the most to the potential toxicity response indices in sediments recently deposited in the bay. The potential ecological risk assessment of heavy metals in the bay was highlighted by the use of the benthic biological pollution index (BPI), suggesting that the ERI is a useful toxicity response index, which can quantify the overall ecological risk level to a target environment.  相似文献   

Finite element method for strong reflection of water waves     

Yong-Sik Cho  Woo-Chang Jeong  Seung-Buhm Woo   《Ocean Engineering》2004,31(5-6):653-667

In this study, the propagation of monochromatic water waves over an arbitrarily varying topography is numerically investigated. A finite element model is developed by formulating the diffraction of waves caused by depth changes. Not only the propagating mode but also the evanescent modes are included in the model. The model developed is applied to the study of strong reflection of monochromatic waves over a sinusoidally varying topography. Predicted reflection coefficients are compared with those of available laboratory experiments and the eigenfunction expansion method. A very good agreement is observed.  相似文献   

Photometric behaviour of the Be star EW Lacertae     

Jang Hae Jeong  Chang Won Suh  Il-Seong Nha 《Astrophysics and Space Science》1986,119(1):73-76

The night-to-night and short-term variations inUBV light curves of EW Lac which were made during 1982–1984 at Yonsei University Observatory are discussed. The long-term variability in the photometric behaviour of the star is examined with our own data as well as those of Harmanecet al. (1980).Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.Yonsei University Observatory Contribution No. 23.  相似文献   

Uncoupled analysis of stabilizing piles in weathered slopes   总被引：15，自引：0，他引：15  

Sangseom Jeong  Byungchul Kim  Jinoh Won  Jinhyung Lee 《Computers and Geotechnics》2003,30(8):671-682

This paper describes a simplified numerical approach for analyzing the slope/pile system subjected to lateral soil movements. The lateral one-row pile response above and below the critical surface is computed by using load transfer approach. The response of groups was analyzed by developing interaction factors obtained from a three-dimensional nonlinear finite element study. An uncoupled analysis was performed for stabilizing piles in slope in which the pile response and slope stability are considered separately. The non-linear characteristics of the soil–pile interaction in the stabilizing piles are modeled by hyperbolic load transfer curves. The Bishop's simplified method of slope stability analysis is extended to incorporate the soil-pile interaction and evaluate the safety factor of the reinforced slope. Numerical study is performed to illustrate the major influencing parameters on the pile-slope stability problem. Through comparative studies, it has been found that the factor of safety in slope is much more conservative for an uncoupled analysis than for a coupled analysis based on three-dimensional finite element analysis.  相似文献   

The Korean emissions trading scheme: business perspectives on the early years of operations     

Sunhee Suk  SangYeop Lee  Yu Shim Jeong 《Climate Policy》2018,18(6):715-728

Korea’s domestic emissions trading scheme commenced in January 2015. It targeted mainly industrial and power sectors, and compelled companies to transform how they manage energy efficiency and mitigate GHGs. This study sets out to explore how Korean companies evaluated their allocation position and engaged in emissions trading in the first compliance period, and to identify their views on trading barriers and policy expectations at the start of emissions trading. Questionnaire surveys and on-site interviews targeting Korean companies under the Korean emissions trading scheme were conducted at the start of operations (February to March 2015) and after the first compliance year (May 2016), respectively. Actual operation results are observed and compared with the survey findings. This study extrapolates implications for policy and presents suggestions for the government and the target companies in terms of how to improve the current emissions trading scheme in order to further stimulate emissions trading.

POLICY RELEVANCE

This study attempts to bridge the gap between companies and government policy in operating the domestic emission trading scheme in Korea. Empirical results, based on analysis of company-level data, reveal how businesses perceive K-ETS and how this relates to the operating results, which saw only limited trading of surplus emissions taking place in the early phase. Key barriers to active trading identified in the study include supply–demand imbalance, policy uncertainty and lack of preparedness of companies over carbon pricing. These barriers could be addressed by improved transparency of allowance allocation methods, possibly restricting carry-over of surplus allowances, ending policy uncertainty and providing more information to companies that can support companies’ policy understanding of the carbon pricing based on the market mechanism. Targeted companies should proactively participate in emissions trading in the early phase, in order to learn from it and prepare for the future introduction of auctioning.  相似文献