• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.33 no.1
• /
• pp.59-63
• /
• 1988

Freshly harvested and depulped Korean ginseng seeds were subjected to the seed treatment of removing endocarp plus surface sterilization with sodium hypocloride, surface sterilization only, and nontreated control. These seeds were stratified at temperatures of 5$^{\circ}$, 10$^{\circ}$, 15$^{\circ}$ and 20$^{\circ}C$ for 20, 40, 60, 80 and 100 days. Embryo growth of the ginseng seeds of which endocarp was removed was most rapid in each stratification temperature and that of sterilized seeds was slower than unsterilized seeds after 80 days stratification at 15$^{\circ}$ and 20$^{\circ}C$. About 15$^{\circ}C$ was an optimal stratification temperature for embry growth in ginseng seeds. Chilling treatment at 5$^{\circ}C$ for 100 days was needed for better germination of dehisced ginseng seeds. An optimal germination temperature for the ginseng seed following chilling treatment was about 15$^{\circ}C$.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.5 no.2
• /
• pp.57-65
• /
• 1999

The in situ observations and the seawater analyses were conducted at all seasons from July 1996 to April 1999 for the purpose of describing the characteristics of seasonal variations of water quality in Mokpo harbour, Korea. Vertical stratification started to be formed in water column in spring, developed in summer and disappeared in fall. In summer, vertical density distribution of water column was found to be in stable structure with lower temperature and higher salinity of bottom water, and the vertical mixing of water between surface and bottom layers was restricted. In winter, however, surface water was found to be similar to bottom water in temperature and salinity, and water column was in unstable structure and in well-mixed condition between surface and bottom waters. The saturation percentage of dissolved oxygen(DO) in bottom water of inner part of Mokpo harbour at all seasons was shown to be decreased to the third grade or under the third grade of Korean standards of seawater quality. In particular, dissolved oxygen was oversaturated in surface water and undersaturated in bottom water in summer, due to stratification and organic pollution. The difference of DO concentration between surface and bottom waters was found to be greater in spring and summer than in fall and winter, due to stratification and photosynthesis of phytoplankton. The concentrations of chemical oxygen demand(COD) over the entire waters of Mokpo harbour were found to fluctuate from below the third grade to the first grade of Korean standards through all seasons and COD concentrations of same seasons were shown to be different year after year. In particular, in view of COD, the annual average seawater quality of Mokpo harbour was evaluated to be in third grade of Korean standards, due to organic pollution. The average COD of surface water was greater than that of bottom water in spring and summer, due to the autochthonous COD caused by production of phytoplankton in surface waters, while the average COD of surface water was similar to that of bottom water in fall and winter, due to the vertical mixing of water between surface and bottom layers.

• Ocean and Polar Research
• /
• v.30 no.3
• /
• pp.261-275
• /
• 2008

The profile of a fixed site at station M ($34.77^{\circ}N,\;129.13^{\circ}E$) in the Korea Strait was studied from March 2006 to February 2007. The aim was to understand the relationship between the annual thermal stratification pattern and seasonal variation in phytoplankton community structure. Physicochemical factors including temperature, salinity and nutrient concentrations, which strongly influence the proliferation and diversity of phytoplankton, were measured. The study period was divided into three due to the characteristic of thermohaline structures; mixed I (March-May 2006), stratified (June-November 2006) and mixed II(December 2006-Feburuary 2007). Diatoms dominated during the mixed I (89%) and II (48%) periods, while nanoplankton group occupied over 83% of total population during the stratified period. The dominant species during the mixed I and II was Chaetoceros socialis (47% and 29%, respectively), while during the stratified period Gyrodinium sp.(4%) was the most dominant. Averaged total chl a concentrations during the mixed I and II periods were 0.61 mg $m^{-3}$ and 0.72 mg $m^{-3}$, respectively, which were at least two-fold higher than that during the stratified period (0.30 mg $m^{-3}$). The vertical mixing and convection process of the water column induced nutrient supply from the bottom layer to the euphotic zone. It also led to the dominance of diatoms during the mixed periods, whereas small phytoplankton prevailed over large phytoplankton as stratification blocked the upward movement of nutrients to subsurface during the stratified period. During the mixed I and II periods, microplanktonic chl a dominated concentrations (50% and 48%, respectively), while picoplanktonic chl a occupied over 37% of total chl a during the stratified period.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.15 no.3
• /
• pp.186-197
• /
• 2012

In order to understand hydrodynamic and water quality changes on the Saemangeum reservoir in accordance to inner development plan, intensive numerical simulations using EFDC have been done. Due to inner dike construction and proposed dredging plans, stratification might occur and yield flow field change. It should be noticed that very conditional gate operation schedule adjusting target water elevation of -1.5 meter causes severe stratification and hence plays an important role in poor water qualities. By using random walk particle tracking residence simulations, it is found that hydrodynamic characteristics depends greatly on riverine inflow conditions. It is also inferred that the northern part of the Mangyeong reservoir behaves as a dead zone and acts as major reasoning of water quality deterioration owing to benthic flux from long-term residing settled sediment.

• Korean Journal of Social Welfare
• /
• v.68 no.2
• /
• pp.27-51
• /
• 2016

This paper is about the NOOMP(Not Out of My Pocket) phenomenon, the inconsistent welfare attitude for an expansion of welfare system and increase of financial resources. By analyzing the scale and influential factors of the NOOMP to the main welfare programs, focusing on the class, gender, and age group, the paper tries to investigate the relationship between the NOOMP and the inherent stratification structure of each programs. This paper uses the Additional Survey of Welfare Attitude in 2013 Korea Welfare Panel Survey. As a result of analysis, low level of NOOMP phenomenon has been observed in welfare programs for whole society members such as health policies, pension, employment policies, compared to those of targeted programs for the poor, aged, or disabled. In addition, high probability of each group of 'low incomer', 'female', and '20s or less'to the NOOMP phenomenon has been appeared, therefore, high relevance of the NOOMP and the stratification structure of welfare programs have been confirmed. These results indicate that the transition to the universal welfare programs and the improvement of welfare programs for more equal structure are needed to reduce the NOOMP phenomenon.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.14 no.1
• /
• pp.21-27
• /
• 2008

Triangular structure is used as basic shape of artificial structures for generating the upwelling current in order to make rich fishing ground at sea. Artificial upwelling current could bring the deep sea water containing a lot of nutrients from the bottom up to the surface. The purpose of this study is to examine the flow characteristics around underwater triangular structure with various stratification parameter. An experimental study was carried out for the triangular structure model in the circulating water channel to investigate flow characteristics by flow visualization method. A velocity fields around the underwater structure were measured by particle image velocimetry(PIV). The experimental results showed that the upwelling effect at the back and upper region of the structure could be best when the water depth was 2 times of the structure height and the stratification parameter was approximately 3.0. These quantitative data will be useful to determine the functional efficiency cf artificial upwelling structures.

• Korean Journal of Environment and Ecology
• /
• v.12 no.3
• /
• pp.224-235
• /
• 1998

Floristic composition of Kyongpo Provincial Park area were investigated from June, 1997 to June, 1998. Vascular plants were composed of 87 families, 240 genera, 281 species, 51 varieties, and 7 formae, totaling 339 taxa. Among them, three taxa such as Vicia venosissima, Paulownia coreana, Aster ciliosa were Korean endemic species. Pteridophyta calculation(Pte-Q) was investigated, 0.61. A naturalized plants were 12 species, corresponding to 5.5％ of totaling 218 species in South Korea by Lee and Chon(1995). The dominant species could be represented by Pinus thunbergii and P. densiflora. And its stratification structure were composed as follows : Pinus thunbergii and P. densiflora in tree and subtree layer, Pinus thunbergii, P. densiflora. and Prunus sargentii in shrub layer, and Spodiopogon sibiricus, Festuca ovina, Melandryum firmum, Artemisia princeps, Rumex acetosella, Commelina communis and Plantago depressa in herb layer, respectively. But stratification structure of dominant species appeared very unstable in subtree and shrub layer.

• Journal of the Korean Geographical Society
• /
• v.43 no.4
• /
• pp.511-525
• /
• 2008

Residential segregation is often considered to be one of the social problems that intensify urban inequality This study reviews three different frameworks about the causes of residential segregation and tests their validity in the real world. The review focuses on racial/ethnic residential segregation in U.S. cities since it has been blamed for persistent socio-economic gap among racial/ethnic groups. The three different segregation frameworks include 'spatial assimilation' that attributes segregation to low degree of assimilation and acculturation, 'place stratification' to discriminatory practices in the housing and mortgage markets such as steering, blockbusting, and redlining, and 'resurgent ethnicity' to racial/ethnic preference in residential choice, particularly in-group attraction. As an effort to test their validity, the paper examined residential pattern changes of the four major Asian nationality groups through 1990s and found that their residences got decentralized but re-cluster in some selected suburbs. This supports 'resurgent ethnicity' largely and 'spatial assimilation' only partly.

• Journal of Korean Society of Forest Science
• /
• v.98 no.2
• /
• pp.133-141
• /
• 2009

This study was conducted to support for determining an efficient sampling design for forest resources assessments in South Korea with respect to statistical efficiency. For this objective, different systematic sampling designs were simulated and compared based on an artificial forest population that had been built from field sample data and satellite data in Yang-Pyeong County, Korea. Using the k-NN technique, two thematic maps (growing stock and forest cover type per pixel unit) across the test area were generated; field data (n=191) and Landsat ETM+ were used as source data. Four sampling designs (systematic sampling, systematic sampling for post-stratification, systematic cluster sampling, and stratified systematic sampling) were employed as optimum sampling design candidates. In order to compute error variance, the Monte Carlo simulation was used (k=1,000). Then, sampling error and relative efficiency were compared. When the objective of an inventory was to obtain estimations for the entire population, systematic cluster sampling was superior to the other sampling designs. If its objective is to obtain estimations for each sub-population, post-stratification gave a better estimation. In order to successfully perform this procedure, it requires clear definitions of strata of interest per field observation unit for efficient stratification.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.23 no.6
• /
• pp.442-450
• /
• 2011

A three dimensional random walk particle tracking method is applied to the Saemangeum area in order to find stepwise environmental changes according to long term construction. Flow regime around Mangyeong, Dongjin and Geum river estuary changed greatly due to dike construction. It is distinctive that reduction of Byeonsan area's flow field and stagnant change in the northern part of the inner reservoir. Similar characteristics are found through the tidal excursion analysis. By analysis of the vertical mixing structures according to density stratification based on temperature and salinity variation, a salt wedge and very strong stratification arises in the inner part of the reservoir after final closure, while it has been well mixed or partially mixed estuary during construction. Shrinking of horizontal dispersion and vertical mixing capability may cause adverse effect on water quality not only inner part but also outer region of the Saemangeum reservoir.