Near-surface soil stabilization by enzyme-induced carbonate precipitation for fugitive dust suppression     

Song  Jun Young  Sim  Youngjong  Jang  Jaewon  Hong  Won-Taek  Yun  Tae Sup 《Acta Geotechnica》2020,15(7):1967-1980

Acta Geotechnica - To resolve the environmental and sustainability issues from fugitive dust emission and conventional mitigation methods, multiple experiments were conducted to evaluate the...  相似文献   

Risk Analysis of Breakwater Caisson Under Wave Attack Using Load Surface Approximation     

Dong Hyawn KIM 《中国海洋工程》2014,(6):739-748

A new load surface based approach to the reliability analysis of caisson-type breakwater is proposed. Uncertainties of the horizontal and vertical wave loads acting on breakwater are considered by using the so-called load surfaces, which can be estimated as functions of wave height, water level, and so on. Then, the first-order reliability method（FORM） can be applied to determine the probability of failure under the wave action. In this way, the reliability analysis of breakwaters with uncertainties both in wave height and in water level is possible. Moreover, the uncertainty in wave breaking can be taken into account by considering a random variable for wave height ratio which relates the significant wave height to the maximum wave height. The proposed approach is applied numerically to the reliability analysis of caisson breakwater under wave attack that may undergo partial or full wave breaking.  相似文献   

Holocene transgression of the Rhine river mouth area,The Netherlands/Southern North Sea: palaeogeography and sequence stratigraphy     

KIM M. COHEN 《Sedimentology》2011,58(6):1453-1485

This study presents a detailed reconstruction of the palaeogeography of the Rhine valley (western Netherlands) during the Holocene transgression with systems tracts placed in a precise sea‐level context. This approach permits comparison of actual versus conceptual boundaries of the lowstand, transgressive and highstand systems tracts. The inland position of the highstand Rhine river mouth on a wide, low‐gradient continental shelf meant that base‐level changes were the dominant control on sedimentation for a relatively short period of the last glacial cycle. Systems in such inland positions predominantly record changes in the balance between river discharge and sediment load, and preserve excellent records of climatic changes or other catchment‐induced forcing. It is shown here that the transgressive systems tract‐part of the coastal prism formed in three stages: (i) the millennium before 8·45 ka bp , when the area was dominated by fluvial environments with extensive wetlands; (ii) the millennium after 8·45 ka, characterized by strong erosion, increasing tidal amplitudes and bay‐head delta development; and (iii) the period between 7·5 and 6·3 ka bp when the Rhine avulsed multiple times and the maximum flooding surface formed. The diachroneity of the transgressive surface is strongly suppressed because of a pulse of accelerated sea‐level rise at 8·45 ka bp . That event not only had a strong effect on preservation, but has circum‐oceanic stratigraphical relevance as it divides the early and middle Holocene parts of coastal successions worldwide. The palaeogeographical reconstruction offers a unique full spatial–temporal view on the coastal and fluvial dynamics of a major river mouth under brief rapid forced transgression. This reconstruction is of relevance for Holocene and ancient transgressive systems worldwide, and for next‐century natural coasts that are predicted to experience a 1 m sea‐level rise.  相似文献   

Decadal Changes in Climatological Intraseasonal Fluctuation of Subseasonal Evolution of Summer Precipitation over the Korean Peninsula in the mid-1990s     

WonMoo KIM  Jong-Ghap JHUN  Kyung-Ja HA  Masahide KIMOTO 《大气科学进展》2011,28(3):591-600

Decadal changes in the subseasonal evolution and the phase-locked climatological intraseasonal fluctuation of summertime rainfall over the Korean Peninsula before and after the mid-1990s are investigated.The activity and the migration speed of the monsoon rain band over the East Asian region are altered in the recent decade,resulting in the drier conditions in late spring and the earlier onset of Changma.In early August when a climatological monsoon break was clear in the earlier decade,the precipitation has increased dramatically with a meridional coherency.The response to the enhanced convection over the South China Sea and southeastern China provides a favorable condition for more precipitation in early August through the changes in moisture transport and tropical cyclone passage.  相似文献   

Species delimitation in the green algal genus Codium (Bryopsidales) from Korea using DNA barcoding     

LEE Hyung Woo  KIM Myung Sook 《海洋学报(英文版)》2015,34(4):114-124

Codium, one of the largest marine green algal genera, is difficult to delimit species boundary accurately based on morphological identification only. DNA barcoding is a powerful tool for discriminating species of seaweeds. The plastid elongation factor TU(tuf A) is considered as maker to perform DNA barcoding of green algal species than rbc L gene due to universality and rapid evolution rate. We conducted DNA barcoding application to Codium specimens from the Jeju Island, Korea to overcome the limit of morphological identification and to confirm the species diversity. As a result of applying tuf A marker, we newly generated fifty-five tuf A barcodes to resolve eight species. Tuf A marker exhibited 6.1%–21.8% interspecific divergences, wider than the gap of rbc L exon 1,3.5%–11.5%. Molecular analysis of rbc L exon 1 sequences of Codium revealed eight distinct species like tuf A analysis separated in five phylogenetic groups. DNA barcoding of the genus Codium using tuf A marker is more helpful to overcome the limit of morphological identification, and this is more potential to reveal cryptic species and to resolve the relationships among subspecies than rbc L analysis alone. The complement of tuf A barcoding and rbc L analyses including morphology for the genus Codium in the northwestern Pacific will give much more reliable achievement for discovering species diversity and resolving the phylogenetic relationships.  相似文献   

Simulation of the extreme waves generated by typhoon Bolaven (1215) in the East China Sea and Yellow Sea     

JUN Ki Cheon  JEONG Weon Mu  CHOI Jin Yong  PARK Kwang Soon  JUNG Kyung Tae  KIM Mee Kyung  CHAE Jang Won  QIAO Fangli 《海洋学报(英文版)》2015,34(12):19-28

Record-breaking high waves occurred during the passage of the typhoon Bolaven (1215) (TYB) in the East China Sea (ECS) and Yellow Sea (YS) although its intensity did not reach the level of a super typhoon. Winds and directional wave measurements were made using a range of in-situ instruments mounted on an ocean tower and buoys. In order to understand how such high waves with long duration occurred, analyses have been made through measurement and numerical simulations. TYB winds were generated using the TC96 typhoon wind model with the best track data calibrated with the measurements. And then the wind fields were blended with the reanalyzed synoptic-scale wind fields for a wave model. Wave fields were simulated using WAM4.5 with adjustment of C_d for gust of winds and bottom friction for the study area. Thus the accuracy of simulations is considerably enhanced, and the computed results are also in better agreement with measured data than before. It is found that the extremely high waves evolved as a result of the superposition of distant large swells and high wind seas generated by strong winds from the front/right quadrant of the typhoon track. As the typhoon moved at a speed a little slower than the dominant wave group velocity in a consistent direction for two days, the wave growth was significantly enhanced by strong wind input in an extended fetch and non-linear interaction.  相似文献   

Demersally drifting invertebrates from Kongsfjorden,Svalbård (Arctic Ocean)–a comparison of catches from drift-pump and drift-nets     

Hans-Uwe Dahms  Hyoung-Min Joo  Jae Hyung Lee  Mi Sun Yun  So Hyun Ahn  Sang Heon Lee 《Ocean Science Journal》2015,50(4):639-648

Demersally drifting organisms were collected at Ny Ålesund (Svalbård–Arctic Ocean) to study the taxon composition and relative abundances in the Arctic summer. Catch potentials of two collection devices for demersal drift were compared. A lowvolume submersible drift-pump and a drift-net unit were employed for the collection of demersally drifting biota, particularly for shallow aquatic habitats. With the exception of Appendicularia, Chaetognatha, Coelenterata, and Ctenophora, which were damaged at times, the pump catches were in good condition and sufficient for identification and quantification of less mobile fauna. A comparison of the two devices revealed that the drift-pump collected more specimens than the drift-net. However, the drift-net may have caused an underestimation of the abundances of invertebrates. No differences in identified taxon number and indices of richness, evenness and diversity were found. However, the proportion of invertebrate animals in the two devices was different for the three groups: zooplankton, macrofauna and meiofauna. At Svalbård, zooplankton, larvae of macrofauna, and meiofauna were successfully collected by the two collecting devices. However, the catchibility of the two devices in collecting various invertebrate taxa was different and, therefore, a sound ‘Device Effect’ was revealed.  相似文献   

PDC钻头切削齿布齿设计的新思路          下载免费PDF全文

金永男  陈宗涛  由昌英  段隆臣 《探矿工程》2015,42(5):72-76

切削齿布齿设计是PDC钻头设计的关键。为提高PDC钻头的钻进效率,综合考虑PDC钻头切削齿的设计特点和切削先后顺序等因素,并且通过对PDC钻头单切削齿实验结果进行分析,提出了以冠部轮廓法线为基准的切削齿布齿设计方法。  相似文献   

Metagenomic approach revealed effects of forest thinning on bacterial communities in the forest soil of Mt. Janggunbong,South Korea     

Byeong-Ju Lee  Soo Hyung Eo 《山地科学学报》2018,15(1):59-67

The soil microbiome that plays important ecological roles in mountains and forests is influenced by anthropogenic and natural causes. Human activity, particularly harvesting or thinning, affects the soil microbiome in forests by altering environmental conditions, such as vegetation, microclimate, and soil physicochemical properties. The purpose of this study was to investigate the effects on forest thinning on the diversity and composition of the soil bacterial community. From next-generation sequencing results of the 16S rRNA gene, we examined differences in soil bacterial diversity and community composition before and after thinning at Mt. Janggunbong, South Korea. We identified 40 phyla, 103 classes, 192 orders, 412 families, 947 genera, and 3,145 species from the soil samples. Acidobacteria and Proteobacteria were the most dominant bacterial phyla in the forest soil of Mt. Janggunbong. Soil bacterial diversity measures (richness, Shannon diversity index, and evenness) at the phylum level increased after thinning, whereas species-level taxonomic richness decreased after thinning. Thinning provided new opportunities for bacterial species in Chloroflexi, Verrucomicrobia, Nitrospirae, and other nondominant bacterial taxa, especially for those not found in Mt. Janggunbong before thinning, to settle and adapt to the changing environment. Our results suggested that thinning affected the diversity and composition of soil bacterial communities in forests and mountains.  相似文献   

A Review on Marine N2 Fixation: Mechanism,Evolution of Methodologies,Rates, and Future Concerns     

Bhavya  P. S.  Min  Jun-Oh  Kim  Min-Seob  Jang  Hyo Keun  Kim  Kwanwoo  Kang  Jae Joong  Lee  Jae Hyung  Lee  Dabin  Jo  Naeun  Kim  Myung Joon  Kim  Yejin  Lee  Junbeom  Lee  Chang Hwa  Bae  Hyeonji  Yoo  Hyeju  Park  Sanghoon  Yun  Mi Sun  Lee  Sang Heon 《Ocean Science Journal》2019,54(4):515-528

Ocean Science Journal - Investigations on marine N2 fixation have gained momentum since 1960s with eventual establishments of relevant methodologies to identify species involved and quantify the...  相似文献