• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.561-568
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• 1990

Voltammetric behavior of some light lanthanide ions (La$^{3+}$, Pr$^{3+}$, Nd$^{3+}$, Sm$^{3+}$, and Eu$^{3+}$) in various supporting electrolytes has been investigated by several electrochemical techniques. The peak potentials and the peak currents, their dependency on the concentration, temperature and pH effects, the reversibility of the electrode reactions are described. The reduction of La$^{3+}$, Pr$^{3+}$ and Nd$^{3+}$ in 0.1 M lithium chloride proceeds by a three-electron change directly to the metallic state (Ln$^{3+}$ ＋ 3e- → Ln$^0$) and charge transfer is totally irreversible. However, the reduction of Sm$^{3+}$ in 0.1 M tetramethylammonium iodide and Eu$^{3+}$ in 0.1 M lithium chloride proceeds in two stages (Ln$^{3+}$ ＋ e- → Ln$^{2+}$ and Ln$^{2+}$ ＋ 2e- → Ln$^0$). At pH values lower than ca.4 the hydrated lanthanide species (Ln(OH)$^{2+}$) reduced before the lanthanide ions (Ln$^{3+}$) due to the catalytic effect of hydrogen ions, and peak current increase with in the order Eu$^{3+}$ < Sm$^{3+}$ < Nd$^{3+}$ < Pr$^{3+}$ < La$^{3+}$ in differential pulse polarography. Some representative plots of $i_{pc}V^{-1/2} (proportional to current function) vs. V show considerable influence of hydrogen ion/lanthanide ion concentration in cyclic voltammetry. It is shown that a reaction of lanthanide ions with proton and/or water and catalytic reaction is enhanced at lower pH and at decreased lanthanide ion concentration.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.4
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• pp.217-224
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• 2014

Cochlodinium polykrikoides is a typical harmful algal species which generates the red-tide in the coastal zone, southern Korea. Accurate algal growth model can be established and then the prediction of the red-tide occurrence using this model is possible if the information on the optimal growth model parameters are available because it is directly related between the red-tide occurrence and the rapid algal bloom. However, the limitation factors on the algal growth, such as light intensity, water temperature, salinity, and nutrient concentrations, are so diverse and also the limitation function types are diverse. Thus, the study on the algal growth model development using the available laboratory data set on the growth rate change due to the limitation factors are relatively very poor in the perspective of the model. In this study, the growth model on the C. polykrikoides are developed and suggested as the optimal model which can be used as the element model in the red-tide or ecological models. The optimal parameter estimation and an error analysis are carried out using the available previous research results and data sets. This model can be used for the difference analysis between the lab. condition and in-situ state because it is an optimal model for the lab. condition. The parameter values and ranges also can be used for the model calibration and validation using the in-situ monitoring environmental and algal bloom data sets.

• Korean Journal of Environmental Agriculture
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• v.42 no.1
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• pp.52-62
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• 2023

This study focused on determining the specific causes and prevention methods of mass fish deaths occurred in five reservoirs (Gagugi, Neupgokgi, Danggokgi, Sagokji, and Hangokji) in Andong-si. For this purpose, a survey of agricultural land and livestock in the upper part of the reservoirs and analysis of water quality in the reservoir irrespective of whether it rains or not were conducted. We attempted to examine the changes in dissolved oxygen (DO) in the surface and bottom layers of reservoirs and changes in DO depending on the amount of livestock compost and time. Based on the above investigations, treatment plans were established to efficiently control the inflow of contaminated water into reservoirs. The rainfall and farmland areas in the upper part of the reservoir were investigated using Google and aviation data provided by the Ministry of Land, Infrastructure, and Transport. The current status of livestock farms distributed around the reservoirs was also examined because compost from these farms can flow into the reservoir when it rains. Various water quality parameters, such as phosphate phosphorus (PO₄-P) and ammonium nitrogen (NH₃-N), were analyzed and compared for each reservoir during the rainy season. Changes in the DO concentration and electrical conductivity (EC) were also observed at the inlet of the reservoir during raining using an automated instrument. In addition, DO was measured until the concentration reached 0 ppm in 10 min by adding livestock compost at various concentrations (0.05%, 0.1%, 0.3%, and 0.5% by wt.), where the concentration of the livestock compost represents the relative weight of rainwater. The DO concentration in the surface layer of reservoirs was 3.7 to 5.3 ppm, which is sufficient for fish survival. However, the fish could not survive at the bottom layer with DO concentration of 0.0-2.1 ppm. When the livestock compost was 0.3%, DO required 10-19 h to reach 0 ppm. Considering these results, it was confirmed that the DO in the bottom layer of the reservoir could easily change to an anaerobic state within 24 h when the livestock compost in the rainwater exceeds 0.3%. The results show that the direct cause of fish mortality is the inflow of excessive livestock compost into reservoirs during the first rainfall in spring. All the surveyed reservoirs had relatively good topographical features for the inflow of compost generated from livestock farms. This keeps the bottom layer of the reservoir free of oxygen. Therefore, to prevent fish death due to insufficient DO in the reservoir, measures should be undertaken to limit the amount of livestock compost flowing into the reservoir within 0.3%, which has been experimentally determined. As a basic countermeasure, minerals such as limestone, dolomite, and magnesia containing calcium and magnesium should be added to the compost of livestock farms around the reservoir. These minerals have excellent pollutant removal capabilities when sprayed onto the compost. In addition, measures should be taken to prevent fish death according to the characteristics of each reservoir.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.47-53
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• 2011

$SF_6$ (Sulfur hexafluoride) possesses high GWP (Global Warming Potential) as sepcified by the IPCC (Intergonvernmental Panel of Climate Change). Recently, the recovery-separtion of $SF_6$ research area, including permeation properties studies using various membrane's materials and the practical operation of recovery-separtion using membrane of waste $SF_6$ gas is in the initial state. The separation efficiency of a single $SF_6$ and waste $SF_6$ mixture was evaluated using a PSF (polysulfone), PC (tetra-bromo polycarbonate) and PI (polyimide) hollow fiber membranes. According to the results of single gases permeation properties, PI membrane has the highest permselectivity of $N_2$ gas in $N_2/SF_6$ gas. Under the condition of P=0.5 MPa, the highest concentration of recovered $SF_6$ is 95.6 vol % in the separation experiment of $SF_6/N_2$ mixture gas by PC membrane. Under the operation pressure of P=0.3 MPa at a fixed retentate flow rate fixed of 150 cc/min, the maximum recovery efficiency of $SF_6$ is up to 97.8% by PSF membrane. From the results above, it is thought that the separation and recovery technique of $SF_6$ gas using membrane will be used as the representative eco-technology in the $SF_6$ gas treatment in the future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.2
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• pp.277-281
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• 1997

The cell density changes of Vibrio mimicus K-1 in sea water and arkshell feeding it were examined at various temperature. The strain was suspended in sterilized sea water and storaged at experimental temperature $(5,\;10,\;15,\;20,\;and\;28^{\circ}C)$). At intervals of up to 10 days, aliquots of each suspension were plated onto BHI agar. At 5 and $10^{\circ}C$, the plate counts of V. mimicus K-1 showed a rapid decline, which 3s known to be a reault of this bacterium's entering into the viable but non culturable state. At 20 and $28^{\circ}C$, however, V. mimicus K-1 are stable over the 10 days experimental periods. V. mimicus K-1 was fed to arkshell, which was subsequently stored at temperatures ranging from 5 to $20^{\circ}C$ for 10 days. The samples of arkshell were homogenized and plated at intervals to determine the cell density of V. mimicus K-1 and total aerobic population of bacteria present. At 5 and $10^{\circ}C$, the numbers of V. mimicus K-1 in sea water rapid decreased over the 10 days experimental periods. However, little change of V. mimicus K-1 density was observed in shellstock arkshell at 5 and $10^{\circ}C$. While, V. mimicus K-1 density was decreased more rapidly to level below limit of dectection in shucked arkshell at same temperature. Incubation at the higher temperature $(20^{\circ}C)$ resulted in large increase in total aerobic bacterial number of shellstock arkshell. These results suggest that even with proper storage, indigenous levels of V. mimicus may remain sufficiently high in shellstock arkshell to produce infection in compromise hosts.

• Korean Journal of Ecology and Environment
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• v.44 no.1
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• pp.9-21
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• 2011

This study is conducted to know the change in water environment of Lake Hwajinpo from 2000 to 2008 with physico-chemical parameters; salinity, dissolved oxygen, total phosphorus and total nitrogen and others. And zooplanktons and phytoplanktons were studied from 2007 to 2008. From the water quality data of Lake Hwajinpo from 2000 to 200S; water temperature, salinity, transparency, chemical oxygen demand and dissolved oxygen ranges are $2.8{\sim}29.4^{\circ}C$, 0.23~33.2‰, $0.2{\sim}1.8\;m$, $0.2{\sim}20.2\;mg\;L^{-1}$ and $0.1{\sim}17.4\;mg\;L^{-1}$ and the average values are $18.0^{\circ}C$, 15.7‰, 0.7 m, $5.7\;mg\;L^{-1}$ and $8.0\;mg\;L^{-1}$, respectively. Total phosphorus (TP) and total nitrogen (TN) ranges are $0.024{\sim}0.869\;mg\;L^{-1}$ (average 0.091) and $0.240{\sim}5.310\;mg\;L^{-1}$ (average 1.235). Average TN/TP ratio is 16.4. The annual variations in COD, TP, TN and Chl.${\alpha}$ are compared. COD in 2000 is $4.83\;mg\;L^{-1}$ and 2008 is $1.80\;mg\;L^{-1}$ which is reduced by $0.34\;mg\;L^{-1}$ every year. TP in 2000 is $0.07\;mg\;L^{-1}$ and 2008 is $0.05\;mg\;L^{-1}$ reduced gradually. Yearly reduction in TN is $0.09\;mg\;L^{-1}$, in 2000 and 2008 the values are $1.54\;mg\;L^{-1}$ and $0.77\;mg\;L^{-1}$ respectivly. Chl.${\alpha}$ in 2000 is $46.30\;{\mu}g\;L^{-1}$ and $5.78\;{\mu}g\;L^{-1}$ in 2008; yearly reduction is $4.50\;{\mu}g\;L^{-1}$. The tropic state index (TSI) in south and north parts of Lake Hwajinpo in 2000 are 67 and 63 which are reduced to 63 and 59 in 2008 respectively. North and south part of Lake Hwajinpo have 67 species of phytoplankton under 47 families in 2007 and 2008. Dominant species in south part in 2007 are; Asterococcus superbus in May, Lyngbya sp. in September and Trachelomonas spp. in November and in 2008 Anabaena spiroides in August are abundant and varies with time. Zooplankton species in Lake Hwajinpo are 25 of 25 families. Dominant species in south part in May and August 2007 and May and November in 2008 Copepoda larvae and in September 2007 Protozoa spp. of Protozoan and Brachionus plicatilis and Brachionus urceolaris of Cladocera in August 2008. Dominant species in north part Asplanchna sp. of Cladecera in August and November 2007 and rest of the time are larvae of Copepoda. In this way, the water quality of Lake Hwajinpo is changing with slow rate in the long period specially nutrients concentration (TP, TN etc) is decreasing.

• Sim-seong Yeon-gu
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• v.38 no.1
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• pp.1-44
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• 2023

Hexagram Bi (比 ䷇ 8) is one of the hexagrams comprised of one-unbroken line and five-broken lines. The hexagrams of one-unbroken and five-broken lines symbolize the relationship and dynamics between one yang-consciousness and the five-yin unconsciousness. The hexagram of one-unbroken line and five-broken lines has six different images depending on the position of the one unbroken line from the beginning line to the top line. In terms of psychology, this means that the position change of one yang line in relation to five yin lines may symbolize the function of consciousness which clarifies and determines the content of the psyche. In addition, the flow of psychic energy can be examined through the process of one unbroken line's movement. In other words, the psychic contents of the beginning line of hexagram Bok (復 ䷗ 24), which is the beginning of the hexagram of one-unbroken line and five-broken lines, proceed sequentially, and then arrive at the process of the last sixth, hexagram Bak (剝 ䷖ 23) through the fifth, the hexagram Bi (8). That is, it can be said that the content of the hexagram and the line determined according to the position of one unbroken line show a certain psychic flow. As a result, the first hexagram Bok (復 ䷗ 24), after recovering and starting newly, means the beginning of consciousness. After that the process of proceeding with the second, third, and fourth lines represents the flow of consciousness. And in the fifth place, the fifth line of hexagram Bi, it reaches its peak and is placed in the optimal state of consciousness because of its right and centered position at this hexagram Bi. Like nature, the psyche gradually enters the path of decline from the highest state, which leads to the last sixth, the top line of hexagram Bak. However, the top line of the hexagram Bak, where everything falls off, contains the content of starting again in its top line. It is the beginning line of hexagram Bok to inherit this. This means the circumambulation of the psyche that changes from a psychologically difficult state of depression to a stage of recovery. There is a stage that must be passed in this circulation process, and that is the hexagram Gon (坤 ䷁ 2). October(tenth month)'s hexagram Gon is placed between hexagram Bak, the ninth month of the lunar calendar, and hexagram Bok, the eleventh month of the lunar calendar. This represents that the flow of recovery must go through a maternal process of hexagram Gon. The retreat to the psychological uterus is inevitable in regenerating the psyche. This process flows from the hexagram Bak and through hexagram Gon to the hexagram Bok. At this situation the hexagram Gon acts the absolutely necessary role. In addition, the main body of the hexagrams of one-unbroken and five-broken lines, including the Bi hexagram, is also the Gon hexagram composed of six-broken lines. In other words, all six hexagrams of one-unbroken and five-broken lines have a certain relationship with the Gon hexagram, and it would be meaningful to look at the correlation between the unbroken lines of the hexagrams of one-unbroken and five-broken lines and the corresponding broken lines of the hexagram Gon. This can be said to be the dynamics of the maternal unconscious connected to the state of consciousness in six forms. Therefore, each hexagram of one-unbroken and five-broken lines symbolizes the expression of the integration the mother archetype with the consciousness. Revealing this well is the meaning of the hexagram of one-unbroken and five-broken lines. Its hexagram image consists of a combination of Gon (☷), which symbolizes the mother, and the thunder (☳) the eldest son, the water (☵) the middle son and the mountain (☶) the third son. As a result, the hexagram Bok (復 ䷗ 24), Sa (師 ䷆ 7), Gyeom (謙 ䷠ 15), Ye (豫 ䷏ 16), Bi (比 ䷇ 8) and Bak (剝 ䷖ 23) are sequentially created in the order of the unbroken line. This is symbolically the evolutionary process of consciousness. In this way, the hexagrams of one-unbroken and five-broken lines, which mean the conjunction of mother and son, represent the advancing relationship between the maternal unconscious and consciousness. In addition, the relationship with the mother according to the position of the son is related to the dynamics of mother archetype to the attitude of consciousness. The psychological meaning can be deduced from the flow of six lines of hexagrams of one-unbroken and five-broken lines. And the state in which the activation of the consciousness is at its peak is the fifth line of the hexagram Bi, and comparing it with the contents of the corresponding fifth line of hexagram Gon not only can find the state and meaning of the conjunction of consciousness and the maternal unconscious, but the entire flow can be compared to the individuation process.

• Journal of the Korean Society of Food Culture
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• v.3 no.2
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• pp.187-195
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• 1988

In accordance with the rapidly growing number of street food service without a registration, a study was undertaken to determine the present state of food service by the covered wagon bar, through an investigation in Jamwondong, around the south gate market and Kangnam subway station, in Seoul, between July 25th and August 25th of 1987. The survey was comprised of three parts: 1) foodservice operation in covered wagon, 2) personal and food handling hygiene, 3) food behaviors of customers. A total of 54 covered wagon bars, consisting of 51.8% mobile bars and 48.2% non-mobile bars, operating in the above three locations, were investigated. Survey results show non-mobile covered wagon bars to be more popular among persons in their thrities and fourties than among teens or the elderly; also among males than females; among company employees and college students than others. Seventy five percent of the mobile covered wagon bars served snack type foods and others served wine and foods for wine, in contrast to hundred percent of the non-mobile covered wagon bars served wine and foods for wine. The survey found many problems of hygiene, in method of food purchasing, menu planning, food preparation, dish washing treatment of leftovers and water supply, as well as personal hygiene. However, customers prefer the casual and popular atmosphere at the counter of the covered wagon bar. Finally, the study emphasizes a need for better operation of covered wagon bar, improvement of food stuff handling and the way of food services and personal hygiene. A change of the registration system from the illegal operation are urgently needed for better quality food services of covered wagon bars.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.435-445
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• 2023

A delta is a depositional landform that is formed when sediment transported by a river is deposited in a relatively low-energy environment, such as a lake, sea, or a main channel. Among these, a delta formed at the confluence of rivers has a great importance in river management and research because it has a significant impact on the hydraulic and sedimentological characteristics of the river. Recently, the equilibrium state of the confluence area has been disrupted by large-scale dredging and construction of levees in the Nakdong River. However, due to the natural recovery of the river, the confluence area is returning to its pre-dredging natural state through ongoing sedimentation. The time-series data show that the confluence delta has been steadily growing since the dredging, but once it reaches a certain size, it repeats growth and retreat, and the overall size does not change significantly. In this study, we developed a model to explain the sedimentation-erosion processes in the confluence area based on the assumption that the confluence delta reaches a dynamic equilibrium. The model is based on two fundamental principles: sedimentation due to supply from the tributary and erosion due to the main channel. The erosion coefficient that represents the Nakdong River confluence areas, was obtained using data from the tributaries of the Nakdong River. Sensitivity analyses were conducted using the developed model to understand how the confluence delta responds to changes in the sediment and water discharges of the tributary and the main channel, respectively. We then used annual average discharge of the Nakdong River's tributaries to predict the dynamic equilibrium positions of the confluence deltas. Finally, we conducted a simulation experiment on the development of the Gamcheon-Nakdong River delta using recorded daily discharge. The results showed that even though it is a simple model, it accurately predicted the dynamic equilibrium positions of the confluence deltas in the Nakdong River, including the areas where the delta had not formed, and those where the delta had already formed and predicted the trend of the response of the Gamcheon-Nakdong River delta. However, the actual retreat in the Gamcheon-Nakdong River delta was not captured fully due to errors and limitations in the simplification process. The insights through this study provide basic information on the sediment supply of the Nakdong River through the confluence areas, which can be implemented as a basic model for river maintenance and management.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.4
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• pp.415-422
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• 2009

We previously demonstrated that zinc plus arachidonic acid (ZA) treatment lowered blood glucose levels in streptozotocin-induced diabetic rats, genetically diabetic obese (ob/ob) mice, and genetically diabetic, non-obese Goto-Kakizaki rats. However, plasma insulin levels did not increase with ZA treatment, suggesting that ZA lowers blood glucose levels not by stimulating pancreatic insulin secretion. However, it is unclear whether these agents lower blood glucose levels by decreasing hepatic glucose output (HGO) or by increasing glucose utilization in peripheral tissues, or both. In order to determine ZA target organ of insulin action, we divided 18 Sprague-Dawley rats weighing ${\sim}130g$ into 3 groups (6 rats per group) and treated them for four weeks with: (1) Control diet (regular rat chow), (2) High fructose (60.0%) diet only, and (3) the same fructose diet plus zinc (10 mg/L) and arachidonic acid (50 mg/L) containing drinking water. After 4 weeks, insulin action was assessed using the hyperinsulinemic euglycemic clamp technique. Food intake and body weights were comparable in all three groups of rats throughout the study period. Plasma glucose and insulin concentrations, glucose uptake, and HGO in the basal state were all the same in these three rat groups. During the clamp study, fructose-treated and fructose+ZA treated rat groups did not exhibit any detectable change on insulin-mediated glucose uptake compared to controls. High fructose feeding impaired insulin mediated suppression of HGO, compared to controls during clamp (4.39 vs. 2.35 mg/kg/min; p<0.05). However, ZA treatment in high fructose-fed rats showed a remarkable increase in hepatic insulin sensitivity compared to high fructose-fed rats, reflected by a complete recovery in suppression of HGO during the clamp (4.39 vs. 2.18 mg/kg/min; p<0.05). This data suggests that ZA increases insulin sensitivity in liver but not glucose utilization of peripheral tissues in high fructose-fed rats.