• Bulletin of the Korean Chemical Society
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• v.27 no.5
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• pp.747-750
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• 2006

Research on tripodal complexes has grown in recent decades and has been subject of numerous reports.1-11 The reasons for this interest include their relevance to model functions of metalloenzymes1-3 and their potential applications in catalysis.13-17 The ligand system used most in this category has been tren, the tripodal tetraamine N(CH2CH2NH2)3, and its derivatives.4 The bz3tren is a versatile tetradentate ligand, known to form stable complexes not only with transition metals5-11 including Cu2+, Zn2+ and Co2+ but also anion species.12 However, only few results on the d10 metal complexes with bz3tren have been reported by us10 and others.6,7 As a part of on going efforts, we therefore focus our attention to extend other d10 system that includes heavy metal ions.

• Korean Journal of Ecology and Environment
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• v.33 no.4 s.92
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• pp.336-341
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• 2000

This study was conducted to clarify the habitat characteristics and distribution of seagrass. Zostera marina L. (Zosteraceae) in the brackish Hwajinpo Lake, Korea in June 1998 and July 2000. Z. marina beds were distributed along the sea-side cost of the lower lake mouth at 0.8 to 1.5m in death, and the seagrass bed area was about 3,200 m$^{2}$. Salinity, water temperature and pH were in the range of 8.0${\sim}$23.0$%_{o}$, 22.0${\sim}$23.7$^{\circ}C$ and 8.34${\sim}$8.62, respectively. Nutrient concentrations were generally now (TN: 24.34 ${\mu}$M, NH$_{4}$-N: 2.57 ${\mu}$M, NO$_{3}$-N: 0.56 ${\mu}$M, NO$_{2}$-N: 0.27 ${\mu}$M, TP: 2.08 ${\mu}$M, PO$_{4}$-P: 0.34 ${\mu}$M). Suspended particulate matters (SPM) concentration averaged 62.8 mg/l and particulate organic matter (POM) averaged 21.3 mg/l. Organic content of SPM averaged 33.9%. The beds substratum was composed of well-sorted, fine sand and its mean brain size was 3.13${\Phi}$. The Z. marina vegetation was almost submerged, and the morphological characteristics can be classified as steno-leaf phenotype by the shoot length, leaf width, and number of leaf vein. Shoot length and leaf width were 70.0${\sim}$126.5 cm and 5${\sim}$7 mm, respectively. Shoot densities ranged from 264 to 296/m$^{2}$, and the plants biomass was estimated at 332.6 to 373.0 g dw/m$^{2}$. Therefore, the habitats of Z. marina in Korea were recognized in a brackish lake, and morphological characteristics appeared to be variable.

• Fire Science and Engineering
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• v.29 no.6
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• pp.13-19
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• 2015

This study was performed to test the combustive properties of Pinus rigida specimens treated with phosphorus (P) and nitrogen (N) additives. Each Pinus rigida specimen was painted three times with 15 wt% P-N additive solutions at room temperature. After drying the treated specimens, the combustion properties were examined using a cone calorimeter (ISO 5660-1). The time to ignition (TTI) for the treated specimens was 90 to 148 s except for the specimen treated with PP/$4NH_4^+$, and the time to flameout (TF) was 556 to 633 s, which was longer than that of virgin plate. While the The specimens treated with P-N additives showed 12.5 to 43.4% higher mean heat release rate ($HRR_{mean}$) and 11.8 to 43.1% higher total heat release (THR) than virgin plate. The effective heat of combustion (EHC) was by 2.9 to 17.5% lower than that of virgin plate. It can thus be concluded that the combustion-retardation properties were partially improved compared to those of virgin plate.

• Korean Journal of Soil Science and Fertilizer
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• v.1 no.1
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• pp.7-11
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• 1968

A high and low productive paddy soils were waterlogged at $30{\pm}2^{\circ}C$ for 35 days in the laboratory. The relation of pH and Eh changes, ferrous iron and ammonium nitrogen of these soils was studied. The results obtained are summarized as follows: 1. pH value has been increased for 13 days of incubation and after 13 th day, they maintain their pH value without marked change, and pH value of high productive soil is higher than that of low productive soil by 0.25-0.30. 2. Eh value has been decreased for 10 days of incubation and then they also maintain their Eh value without marked change. Eh value of high productive soil is lower than that of low productive soil by 50-70 mv. 3. In both soils ferrous iron formed under submerged condition increased steeply within 4-5 days of incubation and after that they maintain their content without marked change. The $Fe^{+{+}}$ content of high productive soil is higher than low productive soil by 1.0 mg/1 gr soil. 4. $NH_4{^{-N}}$ formed under submerged condition rapidly increased in the early period of incubation and after that decreased to a certain level and maintain their content, but its content of high productive soil is higher than that of low productive soil by $20-25{\gamma}/1\;gr$ at the early stage and lower at the latter period by $10-15{\gamma}/1\;gr$.

• Applied Biological Chemistry
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• v.10
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• pp.1-13
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• 1968

Phytin is a salt(mainly calcium and magnesium) of phytic acid and its purity and molecular formula can be determined by assaying the contents of phosporus, calcium and magnesium in phytin. In order to devise a new method for the quantitative analysis of the three elements in phytin, the chelatometric method was developed as follows: 1) As the pretreatment for phytin analysis, it was ashfied st $550{\sim}600^{\circ}C$ in the presence of concentrated nitric acid. This dry process is more accurate than the wet process. 2) Phosphorus, calcium and megnesium were analyzed by the conventional and the new method described here, for the phytin sample decomposed by the dry process. The ashfied phytin solution in hydrochloric acid was partitioned into cation and anion fractions by means of a ration exchange resin. A portion of the ration fraction was adjusted to pH 7.0, followed by readjustment to pH 10 and titrated with standard EDTA solution using the BT [Eriochrome black T] indicator to obtain the combined value of calcium and magnesium. Another portion of the ration fraction was made to pH 7.0, and a small volume of standard EDTA solution was added to it. pH was adjusted to $12{\sim}13$ with 8 N KOH and it was titrate by a standard EDTA solution in the presence of N-N[2-Hydroxy-1-(2-hydroxy-4-sulfo-1-naphytate)-3-naphthoic acid] diluted powder indicator in order to obtain the calcium content. Magnesium content was calculated from the difference between the two values. From the anion fraction the magnesium ammonium phosphate precipitate was obtained. The precipitate was dissolved in hydrochloric acid, and a standard EDTA solution was added to it. The solution was adjusted to pH 7.0 and then readjusted to pH 10.0 by a buffer solution and titrated with a standard magnesium sulfate solution in the presence of BT indicator to obtain the phosphorus content. The analytical data for phosphorus, calcium and magnesium were 98.9%, 97.1% and 99.1% respectively, in reference to the theoretical values for the formula $C_6H_6O_{24}P_6Mg_4CaNa_2{\cdot}5H_2O$. Statical analysis indicated a good coincidence of the theoretical and experimental values. On the other hand, the observed values for the three elements by the conventional method were 92.4%, 86.8% and 93.8%, respectively, revealing a remarkable difference from the theoretical. 3) When sodium phytate was admixed with starch and subjected to the analysis of phosphorus, calcium and magnesium by the chelatometric method, their recovery was almost 100% 4) In order to confirm the accuracy of this method, phytic acid was reacted with calcium chloride and magnesium chloride in the molar ratio of phytic: calcium chloride: magnesium chloride=1 : 5 : 20 to obtain sodium phytate containing one calcium atom and four magnesium atoms per molecule of sodium phytate. The analytical data for phosporus, calcium and magnesium were coincident with those as determine d by the aforementioned method. The new method employing the dry process, ion exchange resin and chelatometric assay of phosphorus, calcium and magnesium is considered accurate and rapid for the determination of phytin.

• Journal of environmental and Sanitary engineering
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• v.13 no.1
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• pp.44-56
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• 1998

This study was performed to investigate the reaction characteristics of piggery wastewater for biological nutrient removal. The reaction characteristics were discussed the fraction of organics, the behavior of nitrogen, nitrification, denitrification, and the behavior of phosphorus. The fraction of readily biodegradable soluble COD was 11-12 percent. The ammonia nitrogen was removed via stripping, nitrification, autotrophic cell synthesis, and heterotrophic cell synthesis. The removal percents by each step were 12.1%, 68.9%, 15.0%, and 4.0%, respectively. Nitrification inhibition of piggery wastewater was found to occur at an influent volumetric loading rate over 0.2 NH$_{3}$-N kg/m$^{3}$/d. Denitrification rates were the highest in the raw wastewater and the lowest in the anaerobic effluent. The denitritation of piggery wastewater came out to be possible, and the rate of organic carbon consumption decreased about 10 percent. The phosphorus removed was released in the form of ortho-p in the aerobic fixed biofilm reactor, it was caused by autooxidation. The synthesis and release of phosphorus were related to the ORP and the boundary value for the phase change was about 170mV. In the synthesis phase, the phosphorus removal rate per COD removed was 0.023mgP$_{syn}$/mgCOD$_{rem}$. The phosphorus contents of the microorganism were 4.3-6.0% on a dry weight basis.

• Journal of Environmental Health Sciences
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• v.15 no.1
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• pp.51-62
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• 1989

This survey was performed to investigate contamination degree and significance in each item of 406 samples of ground water, which was collected in Seoul area from Jan. to Dec. 1988. The results of this study were as follows 1. The unsuitable rate of ground water investigated was 69.7%(32.4% in only bacteria, 23.6% in both bacteria and physico-chemistry and 13.6% in only physico-chemical contamination). 2. The unsuitable rate in each item was the highest(54.2%) in standard plate countland 29.8% in coliform, 12.8% in turbidity, 11.3% in Zn, and 10.8% in Mn. 3. The total mean concentrations in each item were lower than standard except standard plate count, coliform, and Fe. 4. In the analysis of corelation, among items, both total hardness and residual solids were showed very high correlationship (P < 0.01) with other items, and both S.P.C. and coliform showed very highly significant (P < 0.01) with NH$_3$-N.

• Korean Journal of Environmental Biology
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• v.17 no.4
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• pp.529-541
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• 1999

In order to elucidate characteristics of water quality, investigation of monthly dynamics of environmental factors and algal populations at major four stations of the mid and lower part in Taechong Reservoir was performed from June 1998 to June 1999. Water temperature, DO and pH were ranged 5.3~27.7$^{\circ}C$, 6.2~13.8 mgO$_2$/1 and 6.4~9.5, respectively. Those were varying as the season changes. Among inorganic nitrogen nutrients, NH$_4$was ranged from 5.5% to 7.2% of NO$_3$and NO$_3$was almost same through the seasons except summer in which it was low. SRP and SRSi were increased in summer when the blue-green algae became dominant. Those were decreased as the cell density of diatom increased when the water temperature dropped. Therefore SRSi was considered to be another important nutrient factor contributing to the increment of biomass of freshwater algae as well as SRP. Average chi-$\alpha$ concentration ranged from s to 12 $\mu$g/1 and in the lower part or the reservoir, the lowest was found. Moreover, there were remarkable increment in summer when TN/TP ratio were decreasing from relationships between TN/TP ratio and chi-$\alpha$ concentration. Annual mean ratio of TN/TP ratio was relatively high as the value was 110, which was relatively high, and it showed that P is the dominant factor in the algal growth. The dynamics of phytoplankton were simply dominated by a few species seasonally. In summer, blue -green algae such as Anabaena, Microcystis and Oscillatoria were dominant and algal bloom of blue -green began from early summer, sustained to late autumn. The average standing crops of A. spiroides v. crassa, M. aeruginosa and O. limosa were ranged 0.3~2.0$\times$10$^4$cells/ml, 6.4$\times$10$^2$~1.0$\times$10$^4$cells/ml and 4.6$\times$10$^3$~1.6$\times$10$^4$cells/ml, respectively. In winter, diatom Stephanodiscus was considered to be an important species whose average standing crops of Stephunodiscus was 4.9$\times$10$^2$cells/ml from November to April of the next year and the highest was 1.3$\times$10$^3$cells/ml in January.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.79.2-79.2
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• 2017

To dynamically and chemically understand how filaments, dense cores, and stars form under different environments, we are conducting a systematic mapping survey of nearby molecular clouds using the TRAO 14 m telescope with high ($N_2H^+$ 1-0, $HCO^+$ 1-0, SO 32-21, and $NH_2D$ v=1-0) and low ($^{13}CO$ 1-0, $C^{18}O$ 1-0) density tracers. The goals of this survey are to obtain the velocity distribution of low dense filaments and their dense cores for the study of their origin of the formation, to understand whether the dense cores form from any radial accretion or inward motions toward dense cores from their surrounding filaments, and to study the chemical differentiation of the filaments and the dense cores. Until the 2017A season, the real OTF observation time is ~760 hours. We have almost completed mapping observation with four molecular lines ($^{13}CO$ 1-0, $C^{18}O$ 1-0, $N_2H^+$ 1-0, and $HCO^+$ 1-0) on the six regions of molecular clouds (L1251 of Cepheus, Perseus West, Polaris South, BISTRO region of Serpens, California, and Orion B). The cube data for $^3CO$ and $C^{18}O$ lines were obtained for a total of 6 targets, 57 tiles, 676 maps, and $7.1deg^2$. And $N_2H^+$ and $HCO^+$ data were added for $2.2deg^2$ of dense regions. All OTF data were regridded to a cell size of 44 by 44 arcseconds. The $^{13}CO$ and $C^{18}O$ data show the RMS noise level of about (0.1-0.2) K and $N_2H^+$ and $HCO^+$ data show about (0.07-0.2) K at the velocity resolution of 0.06 km/s. Additional observations will be made on some regions that have not reached the noise level for analysis. To identify filaments, we are using and testing programs (DisPerSE, Dendrogram, FIVE) and visual inspection for 3D image of cube data. A basic analysis of the physical and chemical properties of each filament is underway.

• Korean Journal of Environmental Agriculture
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• v.19 no.4
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• pp.276-283
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• 2000

This study was carried out to investigate distribution of epilithic algal and chemical contents of irrigation water influencing in the Seomjin River from March to October in 1996 and 1997. In the water quality of the Seomjin River, the monthly average contents of $NH^+\;_4-N,\;SO_4\;^{2-}$ and $Cl^-$ showed the lowest peak in July and August while that of $NO_3-N$ showed the highest peak in June. The water quality of the Seomjin River was deteriorated by inflow of Yo-cheon and Sosi-cheon in the middle stream. The concentration of anions and cations of the Seomjin River was $Cl^->SO_4\;^{2-}>NO_3\;^->PO_4\;^{3-}\;and\;Ca^{2+}>Na^+>Mg^{2+}>K^+>NH_4\;^+$, respectively. The epilithic algal community identified 339 taxa consisting of 7 forma, 42 varieties and 290 species in 6 classes. In species composition, green algae and diatoms were heavily dominated which were evaluated 50.4% and 31.3% of total classification, respectively. In seasonal distribution, 219 species presented in summer but, 147 species were in winter. In this study, dominant species were Cocconeis placentula var. euglypta and Cosmarium furcatospermum in spering. Cyclotella meneghinasa and Synedra ulna, Scenedesmus ecornis in summer. Melosira varians, Achnathes minutissima in autumn and Gomphonema parvulum in winter were dominated. Finally, the dominant indices in this study have ranged 0.10-0.43.