• 한국지구물리탐사학회:학술대회논문집
• /
• 2000.09a
• /
• pp.54-69
• /
• 2000

There are groundwater trouble by high-salinity yield inducing sea-water intrusion in Cheju Island. It is used groundwater-GIS(Well-lnfo) in the maintenance and management of groundwater in Cheju Island to grasp groundwater trouble area and cause of high-salinity yield. For 16 wells certain to yield high-salinity, we logged specific electrical conductivity(EC) and tried to get hold of freshwater and saltwater relationship. As result of distribution of $Cl^-$ by depth, it is showed up groundwater trouble by high-salinity yield in the east coastal area and the partly north coastal area. The reason of high-salinity groundwater yield are low-groundwater level by the structure of geology and low-hydraulic gradient etc. There is necessity for management to development and use of groundwater in the high-salinity area, special management area.

• Journal of Aquaculture
• /
• v.2 no.2
• /
• pp.53-90
• /
• 1989

Feeding proper level of ration matchable with the appetite of fish will enhance production and also prevent waste of food and its consequence, side effects such as pollution of culture medium. To pursue this goal, elaborate studies on dissolved oxygen concentrations- as the major force in inducing appetite and the growth outcome are necessary. The growth of common carp of 67, 200, 400, 600, and 800 gram size groups was studied at oxygen concentrations ranging from 2.0 to 6 mg/$\iota$ in relation to rations from 1 to as many percent of the initial body weight as could be consumed under constant temperature of $25^{\circ}C$. The results from the experiments are summarized as followings; 1. Appetite: The smaller fish exhibited higher degree of appetite than the bigger ones at the same oxygen concentrations. The bigger the fish the less tolerant it was to the lower oxygen thersholds, and the degree of tolerence decreased as ration level increased. 2. Growth : Growth rate (percent per day) increased - unless consumption was suppressed by low oxygen levels- as the ration was increased to maximum. In case of 67 g fish, it reached the highest point of $5.05\%$ / day at $7\%$ ration under 5.0 mg/$\iota$ of oxygen. In case of 200 g fish, the maximum growth rate of $3.75\%$/day appeared at the maximum ration of $6\%$ under 5.5 mg/$\iota$ of oxygen. In 400 g fish, the highest growth of $3.37\%$/day occurred at the maximum ration of $5\%$ and 6.0 mg/$\iota$ of oxygen. In 600 g fish, the highest growth rate of $2.82\%$ /day was at the maximum ration of $4\%$ under 5.5 mg/$\iota$ oxygen. In case of 800g fish, the highest growth rate of $1.95\%$/day was at maximum tested ration of $3\%$ under 5.0 mg/$\iota$ oxygen. 3. Food Conversion Efficiency: Food conversion efficiency ($\%$ dry feed converted into the fish tissue) first increased as the ration was increased, reached maximum at certain food level, then started decreasing with further increase in the ration. The maximum conversion efficiency stood at higher feeding rate for the smaller fish than the larger ones. In case of 67 g fish, the maximum food conversion efficiency was at $4\%$ ration within 3.0-4.0 mg/$\iota$ oxygen. In 200g fish, the maximum efficiency was at $3\%$ ration within 4.0-4.5 mg/$\iota$ oxygen. In 400g fish, the maximum efficiency was at $2\%$ ration within 4.0 - 4.5 mg/$\iota$ oxygen. In 600 and 800g fish, the maximum conversion efficiency shifted to the lowest ration ($1\%$) and lower oxygen ranges. 4. Behaviour: The fish within uncomfortably low oxygen levels exhibited suppressed appetite and movements and were observed to pass feces quicker and in larger quantity than the ones in normal condition; in untolerably low oxygen the fish were lethargic, vomited, and had their normal skin color changed into pale yellow or grey patches. All these processes contributed to reducing food conversion efficiency. On the other hand, the fish within relatively higher oxygen concentrations exhibited higher degree of movement and their food conversion tended to be depressed when compared with sister groups under corresponding size and ration within relatively low oxyen level. 5. Suitability of Oxygen Ranges to Rations: The oxygen level of 2.0- 2.5 mg/$\iota$ was adequate to sustain appetite at $1\%$ ration in all size groups. As the ration was increased higher oxygen was required to sustain the fish appetite and metabolic activity, particularly in larger fish. In 67g fish, the $2\%$ ration was well supported by 2.0-2.5 mg/$\iota$ range; as the ration increased to $5\%$, higher range of 3.0-4.0 mg/$\iota$ brought better appetite and growth; from 5 till $7\%$ (the last tested ration for 67 g fish) oxygen levels over 4.0 mg/$\iota$ could sustain appetite. In 200 g fish, the 2 and $3\%$ rations brought the best growth and conversion rates at 3.5-4.5 mg/$\iota$ oxygen level; from 3 till $6\%$ (the last tested ration at 200 g fish) oxyge groups over 4.5 mg/$\iota$ were matchable with animal's appetite. In 400, 600, and 800 g fish, all the rations above $2\%$ had to be generally supported with oxygen levels above 4.5 mg/$\iota$.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.45 no.6
• /
• pp.137-148
• /
• 2017

This study analyzed the opinions of residents for desirable urban regeneration and suggested an improvement plan for alley environments. This study conducted a questionnaire survey of the residents living in Alley Garden of Bisan 2,3-dong, Daegu Metropolitan City. In the analysis of the importance and satisfaction of Alley Garden components, items related to a safe, cleanly environment such as 'Lighting facility installation', 'Sewage and waste disposal' and 'CCTV installation' had a high level of importance. It was also found that items improved by the Residential Environment Improvement Project and Alley Garden such as 'Lighting facility installation', 'Quantity of herbaceous flowers' and 'Kinds of herbaceous flowers' had a high level of satisfaction. The IPA results showed that items such as 'Empty house maintenance', 'Rest facilities such as benches and pergolas', 'Space for resident interaction' and 'Public parking lot' had a high level of importance, but had a low level of satisfaction, which suggests that they should be improved by priority. As a result of factor analysis, Alley Garden components were classified into four factors: 'Safety and cleanliness', 'Greenness', 'Exchange and convenience facility' and 'Aesthetics renewal'. Based on this classification, a regression analysis was conducted regarding the effects of the four factors on overall satisfaction. Results showed that all four factors had a significant influence on the overall satisfaction and that 'Aesthetics renewal' and 'Safety and cleanliness', respectively showing levels of significance at 0.274 and 0.235, were highly influential to overall satisfaction. Therefore, it was concluded that spaces for resident interaction and rest facilities should be preferentially installed to improve the environment of alleys. For the improvement of the overall satisfaction of alley environments, it was also concluded that residents should be encouraged to engage in activities such as sculpture installation and mural drawing, along with the introduction of safety bells and crime prevention environment design and the implementation of alley beautification projects.

• Korean Journal of Environmental Agriculture
• /
• v.11 no.3
• /
• pp.185-193
• /
• 1992

To investigate differences in lead content in soils and paddy rices, affected by air pollutants from the Janghang Smelter, soil samples at the different directions, distances, and depths, surface(0-15cm depth) and subsurface(15-30cm depth) in 1982 and 1990, and rice plants at soil sampling sites in 1990 were separately collected at the Janghang Smelter area affected by combustible waste gas from the smelter chimney. Soil samples were extracted with $4M-HNO_3$ and plant samples were digested with mixture of $HNO_3$ and $HCIO_4$ for analyzing by atomic absorption spectrophotometry. The Pb contents in soils ranged from 10.3 to 644.8mg $kg^{-1}$. The average content in 1990 was higher than that in 1982. The Pb content in soils at sites nearer the center of the smelter was higher than that at sites farther from the center. The highest lead content was found at the east direction, and was low in order of east>north-north east>north east > north. The variation of Pb level in soils at east sites was more considerable than other directions. The Pb level in surface soils was higher than that in subsurface soils. The contaminated radius of Pb was until 3km all at east, north-north east and north east. A significant correlation was found between Pb content in surface soils of 1982 and that in surface soils of 1990, between Pb content in soils and contents of Cd and Zn in soils, and between Pb content in soils and soil properties as organic matter, available silicate, cation exchange capacity, exchangeable $Ca^{++}$, $Mg^{++}$ and $Na^+$. Pb content in brown rice was low in the panicle axis, and brown rice, and Pb content in stem was 3.26 times of that in brown rice. Pb content in brown rice ranged from 2.2 to 9.0 mg $kg^{-1}$.

• Korea journal of population studies
• /
• v.19 no.2
• /
• pp.107-137
• /
• 1996

Under-utilization of Korean women's education in the labor market has been observed and pointed out as a waste of valuable human resources. Although education provides women with positive returns when they work, it has been found that Korean women's education is not much related to the likelihood of women's labor force participation. This tendency cannot be explained by micro-economic theory, which says that educated women are more likely to participate in the labor force. Thus, in this analysis, a macro-level explanation is attempted to understand Korean women's economic behaviors in relation to education. Korea's rapid industrialization since 1960 has provided ample job opportunities mostly for less educated women. On the other hand, increasing demand for educated female labor has been moderate. Various restriction against women, especially married women, have prevailed in the Korean labor market. Restrictions against women and the marriage bar tend to be selectively applied to decent white-collar jobs, mostly affecting educated women. Furthermore, there has been no shortage of educated male labor due to its adequate supply. Since Korean women spend most of their adult lives in marriage, married women's low participation in the labor force is a critical factor for the low economic returns to women's education throughout their lifetime. Restriction against married women in the labor market also existed in the past of the United States and the Great Britain. However, along with the expansion of the service sector, married women in great numbers flowed into non-manual jobs. The post-1940 increase of married women in the labor force in those countries can be understood to be a result of a labor shortage for non-manual jobs. Also in Taiwan, which shares many common cultural and economic backgrounds with Korea, the marriage bar has been in decline since the late 1970s, along with an increasing demand for female labor in the service sector. In sum, the changes in the demand structure and the supply of educated male labor force will contribute to the lift of the marrige bar in Korea.

• Journal of Korean Society of Environmental Engineers
• /
• v.37 no.8
• /
• pp.465-471
• /
• 2015

Adsorption experiments for radionuclides such as $^3H$, $^{90}Sr$ and $^{99}Tc$ were conducted using fractured rock collected in unsaturated zone. The released radionuclide through artificial barrier from the near surface repository can be transported by the flow of rainfall or pore water through fractures in unsaturated zone and reach to groundwater flow. Therefore, it is important to investigate transport behavior (retardation) of radionuclides through fractured rock for the safety assessment and long-term performance of repository. Fractured rock samples were collected and characterized by X-ray microtomography (XMT) analysis, which can be used to develop a more robust unsaturated fracture transport model. When fracture-filling materials are exist, distribution coefficient of $^{90}Sr$ is higher than without fracture-filling materials. In this study, batch sorption distribution coefficient ($K_d$) of radionuclide was determined and used to increase our understanding of radionuclide retardtion through fracture-filling materials.

• The Journal of Engineering Geology
• /
• v.27 no.4
• /
• pp.489-500
• /
• 2017

It is not rare that pseudotachylite, dark colored rock with glassy texture, is recognizable in deep core samples drilled up to 900 m from the surface. Pseudotachylite with widths varying few to 20 cm is sharply contacted or interlayered with the host rocks composed of Jurassic granite and Precambrian amphibolite gneiss, showing moderately ductile deformation or slight folding. Pseudotachylite occurring at varying depths in the deep drill core are slightly different in texture and thickness. There is evidence of fault gouge at shallower depths, although brittle deformation is pervasive in most drill cores and pseudotachylite is identified at random depth intervals. Under scanning electron microscope (SEM), it is evident that the surface of pseudotachylite is characterized by a smooth, glassy matrix even at micrometer scale and there is little residual fragments in the glass matrix except microcrystals of quartz with embayed shape. Such textural evidence strongly supports the idea that the pseudotachylite was generated through the friction melting related to strong seismic events. Based on X-ray diffraction (XRD) quantitative analysis, it consists of primary minerals such as quartz, feldspars, biotite, amphibole and secondary minerals including clay minerals, calcite and glassy materials. Such mineralogical features of fractured materials including pseudotachylite indicate that the fractured zone might form at low temperatures possibly below $300^{\circ}C$, which implies that the seismic activity related to the formation of pseudotachylite took place at shallow depths, possibly at most 10 km. Identification and characterization of pseudotachylite provide insight into a better understanding of the paleoseismic activity of deep grounds and fundamental information on the stability of candidate disposal sites for high-level radioactive waste.

• Journal of the Korean Geophysical Society
• /
• v.3 no.3
• /
• pp.175-184
• /
• 2000

A nondestructive experimental feasibility study was conducted using magnetometer to find buried cultural objects at pottery and steel matters in low-relief mountaineous area of Doojeong-dong, Cheonan, Chungnam Province from May 23 to July 18, 1998. Magnetic survey was carried out with $20cm{\times}20cm$ grid in a site of $20m{\times}40m$ before excavation, and the distribution of magnetic anomalies was compared with the results of excavation. Magnetic sensor was located on the surface of ground during the magnetic survey on the basis of an experimental result. Positive magnetic anomalies of maximum 130 nT are found over a pair of potteries. Magnetic anomaly map reveals several anomalous points in the 1st and 4th quadrants of the survey site, from where potteries and their fragments were confirmed. Six points out of seven points cprrelated with magnetic anomaly are found contain earthwares, whereas a magnetically uncorrelated location produced earthware made of unbaked clay. Steel waste such as cans and wires hidden in soil and bushes also influenced magnetic anomalies. Therefore, it is better to remove such steel wastes prior to magnetic survey if possible. Some magnetically anomalous points produced no archaeological object on excavation. This may be explained by shallower level of excavation than burial depth.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.22 no.2
• /
• pp.70-78
• /
• 1989

This experiment was carried out to develop the preparation method of chitosan which has strong antimicrobial activity, and also tried to investigate as a natural food preservative with this chitosan. The antimicrobial activity of chitosan was the strongest when deacetylation of chitin was conducted at $146^{\circ}C$ for 8 hours with $50\%$ sodium hydroxide. The growth of Escherichia coil was completely inhibited by adding this low molecular weight chitosan (M. W, 35,000) at the level of concentration of 75ppm to the medium. The antimicrobial activity was strong enough against such Gram positive bacteria as Staphylococcus sp. and Bacillus sp.. The growth of these strains was inhibited by the concentration of 50ppm but it was varied in its kinds against Gram negative bacteria. The concentration of chitosan re-quired for growth inhibition of microorganisms was 100ppm against Pseudomonas sp. and Vibrio sp., 2,000ppm against Salmonella sp.. The growth of Saccharomyces sp. was inhibited by the concentration of 100ppm, but Hansenula sp., Aspergillus sp., Penicillium sp. and Mu-cor sp. did not inhibited by even more than the concentration of 5,000ppm. The shelf life of Mulkimchi (pickle type Kimchi), containing $0.2\%$ chitosan was 10 days longer than control stored at $5^{\circ}C$.

• Tunnel and Underground Space
• /
• v.29 no.6
• /
• pp.439-455
• /
• 2019

A buffer is the major component of a high level radioactive waste repository. Due to their thermal conductivity and low permeability, bentonites have been considered as a key component of a buffer system in most countries. The deep geological condition generates ground water inflow and results in swelling pressure in the buffer and backfill. Investigation of swelling pressure of bentonite buffer is an important task for the safe disposal system. The swelling pressure that can be critical is affected by mechanical and hydro properties of the system. Therefore, in this study, a sensitivity analysis was conducted to examine the effect of hydro-mechanical (HM) behaviors in the MX-80 bentonite. Based on the results of the swelling pressure generation with HM model parameters, a coupled HM analysis of an unsaturated buffer and backfill in a deep geological repository was also carried out to investigate the major factor of the swelling pressure generation.