Comparative analysis of four stem taper models for Quercus glauca in Mount Halla,Jeju Island,South Korea     

LUMBRES Roscinto Ian Canicosa  LEE Young Jin  CHOI Hyung Soon  KIM Sung Yong  JANG Mi Na  ABINO Azyleah Caizares  SEO Yeon Ok  KIM Chan Soo  PARK Jung Hwan 《山地科学学报》2014,11(2):442-448

This study was conducted to fit the diameter-height data of Quercusglaucain Jeju Island, South Korea to the four commonly used stem taper equations andto evaluate the performance of the four stem taper models using four statistical criteria： Fit index （FI）, root mean square error （RMSE）, bias （）,and absolute mean difference （AMD）. Results showed that the Kozak02stem taper equation provided the best FI（0.9847）, RMSE（1.5745）,（-0.0030 cm） and AMD （1.0990 cm） whileMax and Burkhart model had the poorest performance among the four stem taper models based on the four evaluation statistics （FI ： 0.9793,RMSE ： 1.8272, ： 0.3040 cm and AMD ： 1.3060 cm）. These stem taper equations can serve as a useful tool for forest managers in estimating the diameter outside bark at any given height, merchantable stem volumes and total stem volumesof the standing trees of Quercusglaucain theGotjawal forests located in Mount Halla, Jeju Island, South Korea.  相似文献   

Bed morphological changes around a finite patch of vegetation          下载免费PDF全文

Hyung Suk Kim  Ichiro Kimura  Yasuyuki Shimizu 《地球表面变化过程与地形》2015,40(3):375-388

For the appropriate management and restoration of rivers, isolated vegetation is often a practical means for improving stream habitat and ecology. The effect of a finite vegetation patch on flow and bed morphology in an open channel was investigated using laboratory experiments. The patch containing emergent and submerged vegetation was modeled using circular cylinders and located mid‐channel along a side wall. Several configurations of the patch and submergence ratio (i.e. water depth to the height of vegetation), and two flow conditions (i.e. below and above the sediment motion threshold) were considered. For flows below the sediment motion threshold, erosion occurred primarily on the opposite side of the patch and near the leading edge of the patch. The degree of scouring depth observed in both these regions was affected by the submergence ratio and it increased with the non‐dimensional flow blockage (i.e. the product of the patch density and width). In contrast, for flows above the sediment motion threshold, sediment accumulated within and around the patch due to a reduction in bed shear stress, which was strongly influenced by the flow blockage and the obstruction ratio (i.e. the ratio of patch width to channel width). The eroded area observed within the patch was consistent with the interior adjustment region where the deceleration and diversion of flow occurred through the patch. As the flow blockage increased or as the obstruction ratio decreased, the deposition rate within and behind the patch decreased. Furthermore, the deposition rate increased with an increase in the ratio of flow rate through the patch to total flow rate regardless of the submergence ratio. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Assessment of soil loss in South Korea based on land-cover type     

Chunhwa Jang  Yongchul Shin  Donghyuk Kum  Rogyoung Kim  Jay E. Yang  Sung Chul Kim  Sang Il Hwang  Kyoung Jae Lim  Jeong-Ki Yoon  Youn Shik Park  Younghun Jung 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(8):2127-2141

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Determination of ductility factor considering different hysteretic models     

Li Hyung Lee  Sang Whan Han  Young Hun Oh 《地震工程与结构动力学》1999,28(9):957-977

In current seismic design procedures, base shear is calculated by the elastic strength demand divided by the strength reduction factor. This factor is well known as the response modification factor, R, which accounts for ductility, overstrength, redundancy, and damping of a structural system. In this study, the R factor accounting for ductility is called the ‘ductility factor’, R_μ. The R_μ factor is defined as the ratio of elastic strength demand imposed on the SDOF system to inelastic strength demand for a given ductility ratio. The R_μ factor allows a system to behave inelastically within the target ductility ratio during the design level earthquake ground motion. The objective of this study is to determine the ductility factor considering different hysteretic models. It usually requires large computational efforts to determine the R_μ factor. In order to reduce the computational efforts, the R_μ factor is prepared as a functional form in this study. For this purpose, statistical studies are carried out using forty different earthquake ground motions recorded at a stiff soil site. The R_μ factor is assumed to be a function of the characteristic parameters of each hysteretic model, target ductility ratio and structural period. The effects of each hysteretic model to the R_μ factor are also discussed. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Biomarker-based Seawater Temperatures of Winter Sinking Particles and Core-top Sediment in the Ulleung Basin of the East Sea     

Park  Yu-Hyeon  Kim  Hyung Jeek  Son  Ju Won  Yoo  Chan Min  Khim  Boo-Keun 《Ocean Science Journal》2019,54(3):487-495

Ocean Science Journal - This study evaluates the application of biomarkerbased temperature proxy data (alkenone with its resultant $$U_{37}^{K'}$$ index and glycerol dialkyl glycerol tetraether...  相似文献   

Sinking Particle Flux in the Subtropical Oligotrophic Northwestern Pacific from a Short-term Sediment Trap Experiment     

Hyung Jeek Kim  Jonguk Kim  Dongseon Kim  Michael T. Chandler  Seung Kyu Son 《Ocean Science Journal》2018,53(2):395-403

Time-series sediment traps were deployed in the subtropical oligotrophic northwestern Pacific (SONP) at three depths from August to September 2015 to better understand vertical flux of sinking particles. Sinking particles were collected at 5-day intervals over the sediment trap deployment period. The average total mass flux at water depths of 400 m, 690 m, and 1,710 m was 9.1, 4.4, and 4.1 mg m^-2day^-1, respectively. CaCO₃ materials constituted 50 to 70% of sinking particles while in comparison particulate organic carbon (POC) constituted up to 20%. A synchronous variation of total mass flux was observed at the three depths, indicating that calcite-dominated particles sank from 400 to 1,710 m within a 5-day period. POC flux at these water depths was 2.4, 0.38, and 0.31 mg m^-2day^-1, respectively. Our results indicate low transfer efficiencies of 16% from 400 to 690 m and 13% for the 400 to 1,710 m depth range. The estimated transfer efficiencies were significantly lower than those observed at the K2 station in the northwest Pacific subarctic gyre, presumably because of a prevalence of pico-cyanobacteria in the SONP. Because cyanobacteria have a semi-permeable proteinaceous shell, they are more readily remineralized by bacteria than are siliceous phytoplankton in the northwest Pacific subarctic gyre. Continued surface water warming and expansion of the SONP will likely have a profound impact on ocean acidification in the northwest Pacific, possibly affecting the transfer efficiency of sinking POC to the deep-sea.  相似文献   

Alteration of hydrologic indicators for Korean catchments under CMIP5 climate projections          下载免费PDF全文

Mun‐Ju Shin  Hyung‐Il Eum  Chung‐Soo Kim  Il‐Won Jung 《水文研究》2016,30(24):4517-4542

The change of hydrological regimes may cause impacts on human and natural system. Therefore, investigation of hydrologic alteration induced by climate change is essential for preparing timely proper adaptation to the changes. This study employed 24 climate projections from the Coupled Model Intercomparison Project Phase 5 (CMIP5) under Representative Concentration Pathway (RCP) 4.5 scenario. The climate projections were downscaled at a station‐spacing for seven Korean catchments by a statistical downscaling method that preserves a long‐term trend in climate projections. Using an ensemble of future hydrologic projections simulated by three conceptual rainfall‐runoff models (GR4J, IHACRES, and Sacramento models), we calculated Hydrologic Alteration Factors (HAFs) to investigate degrees of variations in Indicators of Hydrologic Alteration (IHAs) derived from the hydrologic projections. The results showed that the seven catchments had similar trend in terms of the HAFs for the 24 IHAs. Given that more frequent severe floods and droughts were projected over Korean catchments, sound water supply strategies are definitely required to adapt to the alteration of streamflow. A wide range of HAFs between rainfall‐runoff models for each catchment was detected by large variations in the magnitude of HAFs with the hydrologic models and the difference could be the hydrologic prediction uncertainty. There were no‐consistent tendency in the order of HAFs between the hydrologic models. In addition, we found that the alterations of hydrologic regimes by climate change are smaller as the size of catchment is larger. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Emission lines of [Ne IV] in the optical and ultraviolet spectra of gaseous nebulae     

Keenan  Aller  Bell  Espey  Feibelman  Hyung  McKenna  & Ramsbottom 《Monthly notices of the Royal Astronomical Society》1998,295(3):683-690

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Effects of BPA and DES on longchin goby (Chasmichthys dolichognathus) in vitro during the oocyte maturation     

Baek HJ  Hwang IJ  Kim KS  Lee YD  Kim HB  Yoo MS 《Marine environmental research》2007,64(1):79-86

This study was performed in order to assess whether bisphenol (BPA) and diethylstilbestrol (DES) had agonistic or antagonistic effects on oocyte maturation using marine fish. We tested the effects of these chemicals on in vitro maturation, germinal vesicle breakdown (GVBD), assay using oocytes from the longchin goby, Chasmichthys dolichognathus. During the maturation process, low concentrations of BPA and DES triggered GVBD depending on the stage of oocyte development; BPA at 0.044 nM and DES at 0.037, 0.37, and 3.73 nM induced GVBD in 0.82-0.88 mm diameter oocytes (germinal vesicle located near the center of oocytes). In 0.76-0.80 mm diameter oocytes (fully vitellogenic oocytes), BPA induced GVBD at relatively higher concentrations (4.38, 43.8, and 438 nM). In 0.86-0.90 mm diameter oocytes, BPA and DES had no observable effect on GVBD at the concentrations tested. Oocytes with diameters between 0.82 and 0.88 mm appeared to be more sensitive to these chemicals. Moreover, our results showed that BPA and DES did not inhibit GVBD.  相似文献   

Spatial variability of the species composition,abundance, and productivity of the phytoplankton in the white sea in the late summer period     

L. V. Ilyash  I. G. Radchenko  L. L. Kuznetsov  A. P. Lisitzyn  D. M. Martynova  A. N. Novigatskiy  A. L. Chul’tsova 《Oceanology》2011,51(1):19-26

The species composition, cell concentration (N), and biomass (B) of the phytoplankton, as well as the chlorophyll a (Chl a) concentration, primary production (PP), and the concentrations of the dissolved inorganic micronutrients (phosphorus, silica, nitrogen as nitrite), were estimated for Kandalaksha Bay (KB), Dvina Bay (DB), and the basin (Bas) of the White Sea in August of 2004. The micronutrient concentrations were lower compared to the average long-term values for the summer period. The Chl a concentration varies from 0.9 to 2.0 mg/m³ for most of the studied areas, reaching up to 7.5 mg/m³ in the Northern Dvina River estuary. The surface water layer of the DB was the most productive area, where the PP reached up to 270–375 mg C/(m³ day). The phytoplankton biomass varied from 11 to 205 mg C/m³ with the highest values observed in the Bas and DB. Three groups of stations were defined during the analysis of the phytoplankton’s species composition similarity. The dinoflagellates Dinophysis norvegica and Ceratium fusus were particular to the phytoplankton assemblages in the KB; the diatom Ditylum brightwellii was particular to the upper and central parts of the DB. These three phytoplankton species were less abundant in the Bas.  相似文献