• Korean Journal of Ecology and Environment
• /
• v.39 no.1 s.115
• /
• pp.73-84
• /
• 2006

The objective of this study was to analyze long-term temporal trends of water chemistry and spatial heterogeneity for 10 sampling sites of the Yeongsan River watershed using water quality dataset during 1995 to 2004 (obtained from the Ministry of Environment, Korea). The water quality, based on multi-parameters of biological oxygen demand (BOD), chemical oxygen demand (COD), conductivity, dissolved oxygen (Do), total phosphorus (TP), total nitrogen (TN) and total suspended solids (TSS), largely varied depending on the sampling sites, seasons and years. Largest seasonal variabilities in most parameters occurred during the two months of July to August and these were closely associated with large spate of summmer monsoon rain. Conductivity, used as a key indicator for a ionic dilution during rainy season, and nutrients of TN and TP had an inverse function of precipitation (absolute r values> 0.32, P< 0.01, n= 119), whereas BOD and COD had no significant relations(P> 0.05, n= 119) with rainfall. Minimum values in conductivity, TN, and TP were observed during the summer monsoon, indicating an ionic and nutrient dilution of river water by the rainwater. In contrast, major inputs of total suspended solids (TSS) occurred during the period of summer monsoon. BOD values varied with seasons and the values was closely associated (r=0.592: P< 0.01) with COD, while variations of TN were had high correlations (r=0.529 : P< 0.01) with TP. Seasonal fluctuations of DO showed that maximum values were in the cold winter season and minimum values were in the summer seasons, indicating an inverse relation with water temperature. The spatial trend analyses of TP, TN, BOD, COD and TSS, except for conductivity, showed that the values were greater in the mid-river reach than in the headwater and down-river reaches. Conductivity was greater in the down-river sites than any other sites. Overall data of BOD, COD, and nutrients (TN, TP) showed that water quality was worst in the Site 4, compared to those of others sites. This was due to continuous effluents from the wastewater treatment plants within the urban area of Gwangju city. Based on the overall dataset, efficient water quality management is required in the urban area for better water quality.

• The Journal of the Petrological Society of Korea
• /
• v.6 no.3
• /
• pp.210-225
• /
• 1997

From their general natures of peraluminous, S-type and ilmenite-series granites, two-mica granites in the Cheongsan, Inje-Hongcheon, Yeongju and Namwon areas were originated from crust-derived granitic magma and solidified under reducing condition. Each two-mica granite in Inje-Hongcheon and Namwon districts was differentiated from the the residual magma of porphyric biotite granite and high Ti/Mg biotite granite, respectively. The genetic relationships between two-mica granite and porphyritic biotite granite in Chenongsan district and between two-mica granite and biotite granodiorite in Yeongju district are ambiguous. In Namwon district granitic magmas were water-saturated and possible water solubilities in magmas were more than 5.8wt.%. In Yeongju district two-mica granitic magma was nearly water-saturated and showed possible water solubilities between 2.4~5.8wt.%. Two-mica granitic magmas in Cheongsan and Inje-Hongcheon districts were water-undersaturated. Pressure-dependent minimum melt compositions (0.5~2kb) and petrographic textures of two-mica granites in Inje-Hongcheon and Yeongju districts represent that the granites intruded and solidified at shallow level, whereas those in Cheongsan and Namwon districts exhibit relatively deeper level of granitic intrusion (2-3kb). The intersection of granite-solidus/muscovite stability indicates that magmatic primary muscovite can be crystallized from the water-saturated magma above 1.6kb (ca. 6km), but below the pressure muscovite can be formed by the subsolidus reaction. On the other hand, more pressure would be necessary for the crystallization of primary muscovite from the water-undersaturated magma. This pressure condition can explain the occurrence of primary and secondary muscovites from the two-mica granites in the areas considered. The experimental muscovite stability must be cautious of the application to examine the origin of muscovite. The muscovite stability can move toward high temperature field with adding of Ti, Fe and Mg components to the octahedral site of pure muscovite end member.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.29 no.5
• /
• pp.727-743
• /
• 1996

To know the floristic composition, vortical distribution and community structure of marine benthic algae inhabiting in the intertidal and subtidal zones of Yongil Bay, east coast of Korea, the study has performed using the quadrat method along a transect line from July, 1995 to June, 1996. In this area, a total of 144 species including 2 new red algae to Korea was found: 5 blue-green, 18 green, 20 brown and 101 red algae. The representative species throughout the year were Ulva pertusa, Gelidium amansii and Symphyocladia latiuscula. Dominant species were Sargassum thunbergii in spring, U. pertusa in summer and autumn. In winter, Chondrus ocellatus and Monostroma grevillei occurred dominantly. The standing crop exhibited mean value as $185.8g/m^2$ dry weight. Maximum value was recorded in spring $(267.3g/m^2)$ and minimum was observed in winter $(93.7g/m^2)$. Shannon's species diversity (H') and evenness (J') as maximum value were recorded in spring, whereas minimum values were shown in winter. Vertical distribution, rerognized by cluster analysis based on relative coverage of the species, could be divided into two or three algal groups except spring. In general, green algae (M. grevillei, Capsosiphon fulvescens, U. pefusa, Enteromorpha compressa) and brown algae (Sargassum fulvellum, S. thunbergii) were represented in the upper and middle zone and red algae (G. amansii, C. ocellatus, S. latiuscula, Crateloupia okamurae, Pachymeniopsis eilliptica) in the lower zone. The algal community varied according to season and environmental conditions. Particularly, seasonal variation of vortical distribution seemed to be affected primarily by water temperature. Also seasonal tidal level and tolerance of algal species to desiccation appeared to be associated with it in this area.

• Korean Journal of Ecology and Environment
• /
• v.38 no.1 s.110
• /
• pp.54-62
• /
• 2005

The present study was to determine how seasonal rainfall intensity influences nutrient dynamics, ionic contents, oxygen demands, and suspended solids in a lotic ecosystem. Largest seasonal variabilities in most parameters occurred during the two months of July to August and these were closely associated with large spate of rainfall. Dissolved oxygen (DO) had an inverse function of water temperature (r = = = - 0.986, p<0.001). Minimum pH values of<6.5 were observed in the late August when rainfall peaked in the study site, indicating an ionic dilution of stream water by precipitation. Electrical conductivity (EC) was greater during summer than any other seasons, so the overall conductivity values had direct correlation (r = 0.527, p<0.01) with precipitation. Ionic dilution, however, was evident 4 ${\sim}$ 5 days later in short or 1 ${\sim}$ 2 weeks in long after the intense rain, indicating a time-lag phenomenon of conductivity. Daily COD values varied from 0.8 mg $L^{-1}$ to 7.9 mg $L^{-1}$ and their seasonal pattern was similar (r = 0.548, p<0.001) to that of BOD. Total nitrogen (TN) varied little compared to total phosphorus (TP) and was minimum in the base flow of March. In contrast, major input of TP occurred during the period of summer monsoon and this pattern was similar to suspended solids, implying that TP is closely associated (r = 0.890, p<0.01) with suspended inorganic solids. Mass ratios of TN : TP were determined by TP (r= -0.509, p<0.01) rather than TN (r= -0.209, p<0.01). The N : P ratios indicated that phosphorus was a potential primary limiting nutrient for the stream productivity. Overall data suggest that rainfall intensity was considered as a primary key component regulating water chemistry in the stream and maximum variation in water quality was attributed to the largest runoff spate during the summer monsoon.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.18 no.3
• /
• pp.143-156
• /
• 2015

In order to understand the dynamic characteristics of water column environments in the Western Pacific seamount area (approximately $150.2^{\circ}E$, $20^{\circ}N$), we investigated the water mass and the behavior of water column parameters such as dissolved oxygen, inorganic nutrients (N, P), and chlorophyll-a. Physico-chemical properties of water column were obtained by CTD system at the nine stations which were selected along the east-west and south-north direction around the seamount (OSM14-2) in October 2014. From the temperature-salinity diagram, the main water masses were separated into North Pacific Tropical Water and Thermocline Water in the surface layer, North Pacific Intermediate Water in the intermediate layer, and North Pacific Deep Water in the bottom layer, respectively. Oxygen minimum zone (OMZ, mean $O_2$ $73.26{\mu}M$), known as dysoxic condition ($O_2<90{\mu}M$), was distributed in the depth range of 700~1,200 m throughout the study area. Inorganic nutrients typified by nitrite + nitrate and phosphate showed the lowest concentration in the surface mixed layer and then gradually increased downward with representing the maximum concentration in the OMZ, with lower N:P ratio (13.7), indicating that the nitrogen is regarded as limiting factor for primary production. Vertical distribution of water column parameters along the east-west and south-north station line around the seamount showed the effect of bottom water inflowing at around 500 m deep in the western and southern region, and concentrations of water column parameters in the bottom layer (below 2,500 m deep) of the western and southern region were differently distributed comparing to those of the other side regions (eastern and northern). The value of Excess N calculated from Redfield ratio (N:P=16:1) represented the negative value throughout the study area, which indicated the nitrogen sink dominant environments, and relative higher value of Excess N observed in the bottom layer of western and southern region. These observations suggest that the topographic features of a seamount influence the circulation of bottom current and its effects play a significant role in determining the behavior of water column environmental parameters.

• Korean Chemical Engineering Research
• /
• v.45 no.6
• /
• pp.638-647
• /
• 2007

In this study, we present the evaluation chart for assessing the applicability of $CO_2$ flooding method to oil reservoirs. The evaluation chart consists of four categories as source availability, miscibility, applicability and injecting method of miscible flooding. The applicability of reservoir and oil in the chart has basic items of the properties such as oil gravity, viscosity, oil saturation, reservoir temperature and permeability, and these are quantitatively graded. Meanwhile, for additional items of $CO_2$ purity, reservoir thickness and formation dip, they are graded as "highmediumlow". In the case of evaluating the injection method of either continuous injection or WAG ($CO_2$), the qualitative decision will be made according to formation dip, vertical permeability, reservoir thickness, etc. The recommended score in the chart was assigned by utilizing 51 oil producing fields which $CO_2$ flooding is successfully being applied. The evaluation chart developed in this work has been applied to the Captain oil producing field located in Scotland as well as to the Onado oil field of Venezuela, which Korean oil companies have participated in. For the Captain field, the reservoir quality in terms of permeability and porosity is considered to be very excellent to flow the oil. The oil in captain field contains heavier component of $C_{21+}$ as 54%. Therefore, this heavy oil could be immiscibly displaced, hence the evaluating result with the basis of immiscible criteria shows that $CO_2$ immiscible flooding in this field could be properly applied. In the case of Onado oil producing field, since the estimated minimum miscibility pressure is lower than the reservoir pressure, it was assessed that the Onado field would be efficiently conducted for $CO_2$ miscible flooding.

• Korean Journal of Remote Sensing
• /
• v.25 no.5
• /
• pp.423-434
• /
• 2009

The Arctic environment is sensitive to change of sea-ice distribution. The increase and decrease of sea ice work to an index of globe warming progress. In order to predict the progress of hereafter earth global warming, continuous monitoring regarding a change of the sea ice area in the Arctic should be performed. The remote sensing based on an artificial satellite is most effective on the North Pole. The sea ice observation using a passive microwave sensor has been continued from 1970's. The determination of sea ice extent and ice type is one of the great successes of the passive microwave imagers. In this paper, to investigate the seasonal and inter-annual variation of sea-ice distribution we used here the sea ice data from July 2002 to May 2009 around the Arctic within $60^{\circ}N$ for the AMSR-E 12.5km sea-ice concentration, a passive microwave sensor. From an early analysis of these data, the arctic sea-ice extent has been steadily decreasing at a rate of about 3.1%, accounting for about $2{\times}10^5\;km^2$, which was calculated for the sea-ice cover reaching its minimum extent at the end of each summer. It is also revealed that this trend corresponds to a decline in the multi-year ice that is affected mainly by summer sea surface and air temperature increases. The extent of younger and thinner (first-year) ice decreased to the 2007 minimum, but rapidly recovered in 2008 and 2009 due to the dramatic loss in 2007. Seasonal variations of the sea-ice extent show significant year-to-year variation in the seasons of January-March in the Barents and Labrador seas and August-October in the region from the East Siberian and Chukchi seas to the North Pole. The spatial distribution of multi-year ice (7-year old) indicates that the perennial ice fraction has rapidly shrunk recently out of the East Siberian, Laptev, and Kara seas to the high region of the Arctic within the last seven years and the Northeast Passage could become open year-round in near future.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.44 no.4
• /
• pp.586-591
• /
• 2015

To prepare peach wine using peach juice, fermentation properties were monitored, and fermentation conditions (initial sugar concentration, temperature, and time) were optimized by a response surface methodology. Alcohol content for peach wine fermentation ranged from 3.4~9.2% [$R^2=0.9229$ (P<0.01)] and 8.54% (maximum value) at $18.73^{\circ}Brix$, $16.81^{\circ}C$, and 12.99 day. Acidity ranged from 0.30~0.74%, and 0.25% (minimum value) at $15.11^{\circ}Brix$, $17.09^{\circ}C$, and 13.61 day. Residual sugar concentration was $6.67^{\circ}Brix$ (maximum residual sugar content) at $17.79^{\circ}Brix$, $20.63^{\circ}C$, and 3.37 day. Yellow color intensity was 18.92 (maximum Hunter's color b value) at $13.19^{\circ}Brix$, $20.81^{\circ}C$, and 12.81 day. Based on the above study results, optimization conditions for peach wine fermentation were 9 days, below $20^{\circ}C$, and $19^{\circ}Brix$ peach juice.

• Journal of Biosystems Engineering
• /
• v.8 no.2
• /
• pp.39-48
• /
• 1983

This study was performed to obtain the basic data which could be used for the modification of the manual center-burner-type rice-husk furnace into a small scale automatic type for the multi-purpose use in the farm. For this purpose, first, the utilization feasibility of the rice-husk furnace in the farm was analyzed briefly in aspects of available amount of rice-husk for the fuel, annual operation time and replaceble amount of residential heating energy with rice-husk in the farm. For the experiment a prototype furnace geared with an automatic feeding device was fabricated, and feed rate, mold size and chimney height were changed to investigate the combustion efficiency of rice-husk and thermal efficiency of the furnace. Also, optimum and limiting operational factors were observed in each treatments. The results obtained are summarized as follows. 1. If the rice-husk is intensively used for residential heating in the farm for winter season, on an average 51 percent of the total heating energy can be replaced with the rice-husk. Therefore, development of a small scale automatic rice-husk furnace was recognized to be feasible. 2. The operational condition depending on husk-feed rates was very important factor for successive steady burning operation of the given furnace. When the feed-rate was 1.5 kg/hr, the top of the burning zone should be kept at the position about 55 cm from the bottom of the combustion chamber with the periodic removal of ash (termed as steady state position), which was 18 cm above the mold waist. When the feed rates were 2.4 kg/hr and 3.0 kg/hr, the steady state position was at about 4 cm above the mold waist. 3. The mold size affected inflow rate of air into the furnace and consequently CO content in the exhaust gas. The relatively bigger mold gave positive effect on the air-inflow rate. 4. When the husk-feed rates were 1.5 kg/hr, 2.4 kg/hr, 3.0 kg/hr, the combustion efficiencies of the rice-husk were 98.5%, 97.4% and 95.0%, the thermal efficiencies of the furnace were 93.4%, 93.2% and 87.6%, and CO content in the exhaust gas were 1.21%, 1.03%, and 2.43%, respectively. The air-inflow rates were decreased with the increase of feed rates. When the amount of excess air was 30-40%, the CO content in the exhaust gas was at the minimum level. 5. When the chimney height was lowered from 260 cm to 96 cm, the air-inflow rate was slightly decreased, but the average temperature in the combustion chamber, CO content in the exhaust gas and combustion and thermal efficiencies were not changed significantly. 6. The incidental problems associated with the protytype furnace were accumulation of the ash inside the mold, accumulation of the cinder between the outer-drum of the furnace and the combustion chamber wall, and accumulation of the cinder in the chimney.

• Asian-Australasian Journal of Animal Sciences
• /
• v.29 no.5
• /
• pp.739-746
• /
• 2016

A total of 152 pig farms were randomly selected from the five provinces in South Korea. During the experiment, the average temperature and relative humidity was $24.7^{\circ}C$ and 74% in summer and $2.4^{\circ}C$ and 53% in winter, respectively. The correlation between floor space allowance (FSA) and productivity index was analyzed, including non-productive sow days (NPD), number of weaners (NOW), survival rate (SR), appearance rate of A-grade pork (ARA), and days at a slaughter weight of 110 kg (d-SW) at different growth stages. The objectives of the present study were i) to determine the effect of FSA on the pig productivity index and ii) to suggest the minimum FSA for pigs based on scientific baseline data. For the pregnant sow, NPD could be decreased if pregnant sows were raised with a medium level (M) of FSA (3.10 to $3.67m^2/head$) while also keeping the pig house clean which improves hygiene, and operating the ventilation system properly. For the farrowing sows, the NOW tended to decrease as the FSA increased. Similarly, a high level of FSA (H) is significantly negative with weaner SR of farrowing sows (p-value = 0.017), indicating this FSA tends to depress SR. Therefore, a FSA of 2.30 to $6.40m^2/head$ (very low) could be appropriate for weaners because a limited space can provide a sense of security and protection from external interruptions. The opposite trend was observed that an increase in floor space (> $1.12m^2/head$ leads to increase the SR of growing pigs. For the fattening pigs, H level of FSA was negatively correlated with SR, but M level of FSA was positively correlated with SR, indicating that SR tended to increase with the FSA of 1.10 to $1.27m^2/head$. In contrast, ARA of male fattening pigs showed opposite results. H level of FSA (1.27 to $1.47m^2/head$) was suggested to increase productivity because ARA was most affected by H level of space allowance with positive correlation ($R^2=0.523$). The relationship between the FSA and d-SW of fattening pigs was hard to identify because of the low $R^2$ value. However, the farms that provided a relatively large floor space (1.27 to $1.54m^2/head$) during the winter period showed d-SW was significantly and negatively affected by FSA.