• Title/Summary/Keyword: stratification structure

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Potential Meso-scale Coupling of Benthic-Pelagic Production in the Northeast Equatorial Pacific (북동 적도 태평양에서 수층 기초 생산력과 심해저 퇴적물내 미생물 생산력과의 상관성)

  • Kim, Kyeong-Hong;Son, Ju-Won;Son, Seung-Kyu;Chi, Sang-Bum;Hyun, Jung-Ho
    • Ocean and Polar Research
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    • v.33 no.1
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    • pp.21-34
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    • 2011
  • We determined potential meso-scale benthic-pelagic ecosystem coupling in the north equatorial Pacific by comparing surface chl-a concentration with sediment bacterial abundance and adenosine triphosphate (ATP) concentration (indication of active biomass). Water and sediment samples were latitudinally collected between 5 and $11^{\circ}N$ along $131.5^{\circ}W$. Physical water properties of this area are characterized with three major currents: North Equatorial Current (NEC), North Equatorial Count Current (NECC), and South Equatorial Current (SEC). The divergence and convergence of the surface water occur at the boundaries where these currents anti-flow. This low latitude area ($5{\sim}7^{\circ}N$) appears to show high pelagic productivity (mean phytoplankton biomass=$1266.0\;mgC\;m^{-2}$) due to the supplement of high nutrients from nutrient-enriched deep-water via vertical mixing. But the high latitude area ($9{\sim}11^{\circ}N$) with the strong stratification exhibits low surface productivity (mean phytoplankton biomass=$603.1\;mgC\;m^{-2}$). Bacterial cell number (BCN) and ATP appeared to be the highest at the superficial layer and reduced with depth of sediment. Latitudinally, sediment BCN from low latitude ($5{\sim}7^{\circ}N$) was $9.8{\times}10^8\;cells\;cm^{-2}$, which appeared to be 3-times higher than that from high latitude ($9{\sim}11^{\circ}N$; $2.9{\times}10^8\;cells\;cm^{-2}$). Furthermore, sedimentary ATP at the low latitude ($56.2\;ng\;cm^{-2}$) appeared to be much higher than that of the high latitude ($3.3\;ng\;cm^{-2}$). According to regression analysis of these data, more than 85% of the spatial variation of benthic microbial biomass was significantly explained by the phytoplankton biomass in surface water. Therefore, the results of this study suggest that benthic productivity in this area is strongly coupled with pelagic productivity.

Planting Characteristics of Pyeonghwa Park in World Cup Park, Seoul (서울 월드컵공원 평화의공원 지구의 식재특성 연구)

  • Han, Bong-Ho;Bae, Jung-Hee;Kim, Ji-Suk;Lee, Kyong-Jae
    • Journal of the Korean Institute of Landscape Architecture
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    • v.36 no.2
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    • pp.42-52
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    • 2008
  • This paper categorized the functions of and investigated the characteristics of planting in Pyeonghwa Park near the Seoul World Cup Stadium as a preliminary study for improving tree planting in the park. The functions of planting were deduced based on related theoretical studies and an analysis of the intention of design and environmental factors. The characteristics of planting were analyzed after drawing the distribution and stratification of dominant planting species and setting samples by function. The functions of planting were classified into natural landscape planting, buffer planting, and shade planting. For dominant planting species, pine trees and elm-like trees have been widely observed while various species in addition to pine trees in natural landscape planting areas have been introduced in terms of the function of planting. These trees that were randomly planted before the park was developed have been obstacles in the formation of natural landscapes. For buffer planting and topographical correction, tall trees were planted. However, it seems that comprehensive complementary measures should be taken on the under-story planting.

Preliminary Thermal-Hydraulic Analysis of the CANDU Reactor Moderator Tank using the CUPID Code (CUPID 코드를 이용한 CANDU 원자로 칼란드리아 탱크 내부유동 열수력 예비 해석)

  • Choi, Su Ryong;Lee, Jae Ryong;Kim, Hyoung Tae;Yoon, Han Young;Jeong, Jae Jun
    • Journal of Energy Engineering
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    • v.23 no.4
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    • pp.95-105
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    • 2014
  • The CUPID code has been developed for a transient, three-dimensional, two-phase flow analysis at a component scale. It has been validated against a wide range of two-phase flow experiments. Especially, to assess its applicability to single- and two-phase flow analyses in the Calandria vessel of a CANDU nuclear reactor, it was validated using the experimental data of the 1/4-scaled facility of a Calandria vessel at the STERN laboratory. In this study, a preliminary thermal-hydraulic analysis of the CANDU reactor moderator tank using the CUPID code is carried out, which is based on the results of the previous studies. The complicated internal structure of the Calandria vessel and the inlet nozzle was modeled in a simplified manner by using a porous media approach. One of the most important factors in the analysis was found to be the modeling of the tank inlet nozzle. A calculation with a simple inlet nozzle modeling resulted in thermal stratification by buoyance, leading to a boiling from the top of the Calandria tank. This is not realistic at all and may occur due to the lack of inlet flow momentum. To improve this, a new nozzle modeling was used, which can preserve both mass flow and momentum flow at the inlet nozzle. This resulted in a realistic temperature distribution in the tank. In conclusion, it was shown that the CUPID code is applicable to thermal-hydraulic analysis of the CANDU reactor moderator tank using the cost-effective porous media approach and that the inlet nozzle modeling is very important for the flow analysis in the tank.

A Case Study on the Slope Collapse and Reinforcement Method of the Phyllite Slope (천매암 지역에서의 비탈면 붕괴 원인규명 및 보강대책 사례연구)

  • Cho, Younghun;Lim, Daesung;Chun, Byungsik
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.8
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    • pp.83-93
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    • 2010
  • The purpose of this study is to present emergency rehabilitation, cause and the countermeasure of reinforcement about reinforced retaining wall and the slope collapse of the phyllite ground. The study area is broken easily because this area has rock mass discontinuity such as stratification, foliation, joint and fold. And this area consists of the ground where it happens easily to the failure of structure like reinforced retaining wall because of the phyllite ground sensitive to weathering. Counterweight fill in front of reinforced retaining wall was performed as emergency rehabilitation about displacement of reinforced retaining wall and the failure at the rear of slope on phyllite ground. After that, additional displacement didn't occur. Boring and geophysical exploration were launched to present emergency rehabilitation and develop the long-term method of reinforcement. This could grasp anticipated range of the failure section and identify internal and external factors of the cause of the slope collapse. Several methods of reinforcement were suggested by conducting the numerical analysis. When conducting design and construction of major structures at the ground which has complex discontinuities, the precise site investigation should be conducted. During construction, immediate action for over-displacement should be taken by performing the periodic measurement.

A Time Variable Modeling Study of Vertical Temperature Profiles in the Okjung Lake (옥정호의 연직 수온분포에 관한 시변화 모델 연구)

  • Park, Ok-Ran;Park, Seok-Soon
    • Korean Journal of Ecology and Environment
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    • v.35 no.2 s.98
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    • pp.79-91
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    • 2002
  • A time variable modeling study was performed for seasonal variations of vertical temperature profiles in the Okjung Lake located in upstream of the Sumjin River. Based on the model structure of the US Army Corps of Engineer's CE-QUAL-W2, the lake was divided into 3 branches, 50 longitudinal segments and 49 vertical layers and vertical profiles of water temperature and current velocity were simulated over one year. The model results were calibrated and verified against vertical profiles of water temperature measured every month from March 1998 to February 1999 at 5 different locations. The model results showed a good agreement with the field measurements. The hydrologic balance during this period was validated by comparing the simulated values of surface elevation level with the measured data. There was some discrepancy in July data between the model results and the fleld measurements. This could be attributed partially to the inadequacy of the model to the highly hydrodynamic nature of water body and partially to the lack of accuracy in local atmospheric temperature data during summer monsoon period. The model results have shown that there was no seasonal over-turn in most part of the Okjung Lake, where water temperature maintained above $4^{\circ}C$ over one year. In the upstream shal-low area (depth<20 meter), however, temperature at surface layer fell below $4^{\circ}C$ and water was frozen such that slight over-turn would occur during winter period. From this study, we concluded that the Okjung Lake is oligomictic. This conclusionis significantly different from the general pattern that the lakes located from $20^{\circ}C$ to $40^{\circ}C$ latitude would be warm monomictic. From the examination of simulated current velocity distribution, it was found that the upstream inflows would infiltrate into mesolimnion of the lake during hydrodynamic summer monsoon periods due to the thermal density of water.

A Study on China Coastal Water Appeared in the Neighbouring Seas of Cheju Island (제주도 주변해역에 출현하는 중국대륙연안수에 관한 연구)

  • KIM In-Ok;RHO Hong-Kil
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.27 no.5
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    • pp.515-528
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    • 1994
  • China Coastal Water(CCW) appeared in the neighbouring seas of Cheju Island has been analyzed and the results are as follows: The water with salinity below $32.20\%0$ in the neighbouring seas of Cheju Island in summer is thought CCW. During the period from April 1985 to August 1986, salinity of more than $34.00\%0$ was appeared in the Cheju Strait during January to mid May, but it decreased gradually from late May. CCW with salinity below $32.20\%0$ appeared in the Cheju Strait in early July and disappeared in October. The mean thickness of CCW in the Cheju Strait was about 25m and CCW had an influence of up to about 50m depth. And stratification structure of the Cheju Strait in summer was halocline between the surface and 50m depth and homogeneous salinity layer below 50m depth. It seems that although CCW appears in the wide area of neighbouring seas surface of Cheju Island in summer, the core of this CCW which has the lowest salinity flows into the Cheju Strait from the western seas of Cheju Island. This CCW flows out the east through the central part of the Cheju Strait and then seems to be transported further in the form of eddy.

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Vegetation Status and Characteristics of the Spatial Distribution in Taeanhaean National Park (태안해안국립공원 식생 현황과 공간분포 특성)

  • Lee, Seon-Mi;Myeong, Hyeon-Ho
    • Korean Journal of Ecology and Environment
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    • v.48 no.2
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    • pp.122-128
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    • 2015
  • This study aims to figure out the vegetation status and characteristics of the spatial distribution in Taeanhaean National Park. As a result, vegetation communities were Pinus thunbergii community, Pinus densiflora community, Pinus thunbergii-Pinus densiflora community, Camellia japonica community, Carpinus turczaninowii community, Carpinus turczaninowii-Pinus thunbergii community, Kalopanax septemlobus community, Koelreuteria paniculata community, Robinia pseudoacacia community, and sand dune and coastal wetland vegetation including Vitex rotundifolia community, Elymus mollis community, Calamagrostis epigeios community, Ischaemum anthephoroides community, Zoysia sinica community, Suaeda maritima community, and Phragmites communis community. Landscape types in actual vegetation map were Pinus thunbergii community (3.92%), Pinus densiflora community (1.40%), Robinia pseudoacacia community (0.05%), sand dune and coastal wetland vegetation (0.11%), field (0.46%), seashore (0.24%), thinning area (0.08%), bareground (0.16%), and sea (93.58%). Area of Pinus thunbergii community among vegetation type was $14.797km^2$ (3.92%) and the largest. Stratification structure and species composition of Pinus thunbergii community distributed in the seashore were different as a result of disturbance and human use. On the other hand, we assumed that succession will take place to the potential natural vegetation that is Quercus serrata and Quercus dentata in undisturbed Pinus thunbergii community. Meanwhile, Erechtites hieracifolia was occupied in understory of Pinus thunbergii community around the seashore and Diodia teres was invaded to sand dune vegetation. They may affect on natural species negatively. Therefore, monitoring and management plans are necessary.

The Custom of Bride Wealth in Africa: The Context of Change and Reconstruction (아프리카의 신부대(bride wealth) 관습: 변화와 재구성의 맥락)

  • Seol, Byung-Soo
    • Cross-Cultural Studies
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    • v.50
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    • pp.131-172
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    • 2018
  • It is noted that nowadays, the bride wealth custom takes an extremely distorted form in African society. Such a phenomenon is a result that the male-dominant culture, Western religions, and capitalist economic system have been negatively combined into dynamic factors seen as bride wealth. This means that the concept of bride wealth has been incessantly reconstructed in the middle of clash and conflict of tradition and modernity. There is also little doubt that the practice is inextricably tangled with the common and current ways of livelihood, early marriage, polygyny, kinship/family structure, poverty, and migration labor. Bride wealth has become an increasingly commercialized element under a capitalist economic system. Accordingly, its traditional symbolism is seen to be subsequently weakening, whereas a tendency towards the reification of women is strengthening more in modern society that embraces modern customs bent on the protection of women's human rights. Its commercialization has produced a result, which instigates the noted violations of women's basic human rights, gender inequality, and promotion of domestic violence. The ways that people perceive bride wealth vary according to their own sex, generation, stratification, and ethnic background. Those people who negatively recognize bride wealth will increase with the deepening of its commercialization due to the influence of capitalism. Its color and effect will deepen and depend on how its agents correspond to socioeconomic changes. They will constantly reinterpret and reconstruct it within their own environments, but the basic human rights efforts are constantly under review by concerned individuals seeking to promote equality for women as a global effort.

Selecting the Optimal Research Time for Forest Birds Census in Each Season (산새류의 계절별 적정 조사시간 선정 연구)

  • Kim, Mi-Jeong;Lee, Soo-Dong;Kim, Ji-Suk
    • Korean Journal of Environment and Ecology
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    • v.27 no.2
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    • pp.219-229
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    • 2013
  • This research is performed in order to suggest seasonal effective research time that is applied to wild birds research which lives in a forest. The subject area of this research is Mulgun-ri village forest in Samdong-Myeon, Namhe-gun. To investigate suitability of the project, existing land-use, existing vegetation, vegetational structure, and etc. of the subject and whole area are figured out. To suggest adequate research time, based on seasonal sun rise and set time for 3days, repetitive research is performed at hourly intervals. The subject area is connected with a forest and is possible for forest wild birds to flows in and provides various habitats and feeding areas. And also the subject area is a appropriate area for wild birds research and is like a natural forest in that a layer structure development of the forest itself, a distribution of Zelkova serrata and Aphananthe aspera and so on. 105 species which is observed in subject area are categorized and mountain birds are classified. After time-based peak value is selected in each season, hourly species richness, diversity, and index of similarity are analyzed as compared with the appearing number of species and individual bird. As a result, 7~11 hour is the most effective time in spring, and 8~9 hour is the best time. In summer, 6~9 hour is the most appropriate time when whole appearing species are similar to species structure. In fall, 7~11(30~60 minutes after sun rise) when wild birds movements are vigorous is analyzed easy to observe and 8~9 hour is the most appropriate research time because each analysis shows the best values. In winter, 7~12 hour is the most effective time although 10~11 hour is the best time but it is decided that similar results are drawn because hourly deviation is not so big except 1 hour before sun rise. In every four season, it is decided that 30~60 minutes after sun rise is appropriate to research a group of wild birds in the subject area.

Vegetation Structure Characteristics and Management Plan of Mulgeun Fish Shelter Forest in the Southern Coast (남해안 물건리 방조어부림의 식생구조 특성 및 관리방안)

  • Lee, Soo-Dong;Kim, Mi-Jeong;Kang, Hyun-Kyung
    • Journal of the Korean Institute of Traditional Landscape Architecture
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    • v.34 no.1
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    • pp.118-128
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    • 2016
  • The purpose of this study is to present efficient methods of preserving and managing the fish shelter forest in Mulgun-ri on the southern coast of Korea on the basis of its humanistic, sociological and ecological characteristics. The study object is Korean natural monument No. 150, which is presumed to have been forested by descendants of Jeonju Lee Family who settled there, and village rituals are held every October to pray for the peace of the village. The forest is managed by Namhae-gun as a historical and cultural resource as well as its disaster-preventing, economic, and environmental and ecological functions. The linear form of the area is $23,962.6m^2$ and farmland(48.5%) and urbanization area(38.2%) are extensively located in its periphery area. Actual vegetation was sub-classified into three types of land according to use pressure and whether or not damage was done: land where its stratification was formed; land where it was restored, and the land where it was damaged. Plant communities were sub-classified into Aphananthe aspera community(I) and Zelkova serrata community(II) which had a low use pressure; Z. serrata-Chionanthus retusa-A. aspera community(III) and A. aspera-Z. serrata community(IV) which had a high use pressure; and Celtis sinensis-A. aspera community(V) whose underlayer was damaged by use. Fragmentation of the forest is under way and its inside vegetation growth is hampered due to the installation of traffic and resting facilities such as the through roads costal roads, wooden-deck walkways, parking lots, washstands, etc. As a restoration management plan for this, the following were required: an establishment of preferred restoration area; a selection of restoration vegetation species; and an appropriate restoration method. The damaged area($7,868.2m^2$) will have to be set up as the preferred restoration area; seedlings of restored vegetation species should be raised with dominant species within the forest(i.e., Z. serrata, A. aspera, C. sinensis, and C. retusa) as their 'mother trees' for the benefit of for the next-generation forest; and sub-tree and shrub layer should be complementarily planted with 5 and 115 trees(unit $100m^2$) respectively to facilitate the formation of a multi-layered vegetation structure. In addition, resting facilities scattered inside the forest should be demolished; and indiscriminate use of them should be controlled; management and monitoring should be carried out so that the area can be preserved and restored as a deciduous broad-leaved forest.