• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.1
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• pp.42-46
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• 2004

Deep Ocean Water (DOW) is formed within restricted area including polar sea (high latitude) by cooling of surface seawater and globally circulating in the state of isolation from surface seawater. Although it is not as obvious as estuaries mixing, brine ground water is mixture of recirculated seawater and ground water. Seawater having high osmotic pressure infiltrates into an aquifer which is connected to the sea. In order to clarify the characteristics of deep ocean water and brine ground water, we investigated their origins, chemical compositions, water qualities and resources stabilities. While concentrations of stable isotopes (/sup 18/O and ²H) in seawater is 0‰, those in brine ground water is on meteoric water line or shifted toward oxygen line. It means that origin of brine ground water is different than that of deep ocean water. The ions dissolved in seawater (Na, Ca, Mg, K) are present in constant proportions to each other and to the total salt content of seawater. However deviations in ion proportions have been observed in some brine ground water. Some causes of these exception to the rule of constant proportions are due to many chemical reactions between periphery soil and ground water. While DOW has a large quantity of functional trace metals and biological affinity relative to brine ground water, DOW has relatively small amount of harmful bacteria and artificial pollutants.

• Journal of Korean Society of Archives and Records Management
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• v.15 no.2
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• pp.165-179
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• 2015

Archives have historical and academic values. That is why the study of preservation conditions and the environment for the effective management of various records progress. However, materials such as paper and adhesives will inevitably cause biological damages. These damages spread into the inner side of archives, which would make it impossible to recover. For example, archival records from Malaysia and Oman are easily exposed to biological damage because of these countries' hot and humid climate. As such, once records are damaged, disinfection operations are customary in these areas. Methyl bromide (MeBr) and ethylene oxide (EtO) were used in the disinfection process as they showed good insecticidal effect. However their antibacterial effect are negligible. As such, the need for an environmental-friendly fumigator was evident. An environmental-friendly fumigator is designed to improve storage stability. Such equipment is expected to contribute to prevention of damages to cultural heritages through its use of vaporization technology, maintenance of a disinfection space (chamber), and self-generation of nitrogen.

• Journal of Chest Surgery
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• v.30 no.7
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• pp.733-738
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• 1997

Sequential bilateral lung transplantation may result in a variety of perioperative and postoperative complications, showing high perioperative morbidity and mortality rates. This research was performed to investigate the hemodynamic changes in adult mongrel dogs after bilateral reimplantation, two methods preferred for avoiding or minimizing graft rejection. The anterior portion of the pulmonary artery and the left atrium proximal to the superior and the inferior pulmonary veins were resected out and then re-anastomosed one hour later to prevent torsion or stenosis of the anastomotic site and the formation of a thrombosis in the left atrium. An everted suture technique was employed for the left atrium; An hour after the division, however, the main bronchus was tightly anastomose by interrupted sutures of No. 4-0 prolene in a telescope method. A modified I-C solution mixed with PGEI was infused into the cut portion of the pulmonary artery at the rate of 15 mllkglmin and at a pressure of 40 cmH20 for a total dosage of 70 mlfkg in order to preserve the transected lung. Topical cooling using wet gauzes soaked with cold I-C solution was performed for one hour to prevent ischemic lung injury. The above procedures are considered to be beneficial for achieving a satisfactory outcome for bilateral lung reimplantation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.8 s.350
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• pp.13-18
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• 2006

[ $SnO_2$ ] and ZnO nanostructures were grown on the surface of thin film by heat treatment of metal Sn, Zn under Ar gas flow and $O_2$ at atmospheric pressure, respectively. The sensitivity of the $SnO_2$ thin film device on which grown nanowires to CO gas(5,000 ppm) was 50 % at the operating temperature of $200^{\circ}C$. In case of using Pt as catalysts, the sensitivity was enhanced and operating temperature was reduced(73 % at $150^{\circ}C$ ). The sensitivity of the ZnO nanorods device using Cu as catalysts to NOx gas was 90 % at the operating temperature of $200^{\circ}C$. It was found that the sensitivity to CO and NOx gases for the device on which grown nanostructures was much higher than those for general thin film device.

• Journal of the Korean Chemical Society
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• v.35 no.2
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• pp.99-104
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• 1991

Nonstoichiometric solid solutions of Sr$_{1+x}Er _{1-x} FeO _{4-y}$ system (x = 0.00, 0.25, 0.50, 0.75 and 1.00) with layered $K_2NiF_4$ type structure were prepared at 1350$^{\circ}$C under atmospheric pressure. By the analysis of X-ray diffraction, the crystallographic structures of the solid solution of all compositions were found to be pseudo-tetragonal system. Nonstoichiometric chemical formulas have been determined by Mohr salt analysis. It shows that the amount of Fe$^{4+}$ increases with increasing x up to 0.50 and then decreases, and the value of oxygen nonstoichiometry increases with increasing x value. Mixed valency states of Fe$^{3+}$ and Fe$^{4+}$ in the sample were identified again by Mossbauer spectroscopic analysis at 298 K. Electrical conductivity varied within the semiconductivity range of 10-2 ∼ 10-7(${\Omega}$-1cm-1), activation energy for electrical conduction decreased with the increment of the mole ratio of Fe$^{4+}$ or ${\tau}$ value. The conduction mechanism could be explained by the hopping model of the conduction electrons between the valency states of Fe$^{3+}$ and Fe$^{4+}$.

• Journal of the Korean Chemical Society
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• v.37 no.11
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• pp.923-928
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• 1993

The series of solid solutions in the $Sr_{1+x}Ho_{1-x}FeO_{4-y}$ (x = 0.00, 0.25, 0.50, 0.75 and 1.00) systems with $K_2NiF_4$ type structure have been prepared at 1550$^{\circ}$C under an atmospheric air pressure. The X-ray powder diffraction spectra of these samples assign that the crystallographic phases are tetragonal system over the whole x range. The lattice volume was increased with increasing the substitution amount of the $Sr^{2+}$ ion. The mole ratio of the $Fe^{4+}$ ion to total iron ions or ${\tau}$ value has been determined by Mohr salt titration of the sample and then the y value was calculated from x and ${\tau}$ values. The ${\tau}$ and y values have been increased with x values. The nonstoichiometric chemical formula are formulated from the general formula of $Sr_{1+x}Ho_{1-x}Fe^3_{1-}\;^+_{\tau}Fe_{\tau}^{4+}O_{4-y}$ replaced by x,${\tau}$ and y values. Mossbauer spectra show the mixed valence state and coordination state of $Fe^{3+}\;and\;Fe^{4+}$ ions. It is found out that the magnetic property of the samples is paramagnetic at room temperature. Electrical conductivity varied within the semiconductivity range of 1.0 to 1 ${\times}\;10^{-9}{\Omega}^{-1}cm^{-1}$. Activation energy of the electrical conductivity was decreased with the $\tau$ value. The conduction mechanism should be explained by the hopping model of the conduction electrons between the valence states of $Fe^{3+}\;and\;Fe^{4+}$ ions.

• Korean Journal of Environmental Biology
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• v.37 no.2
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• pp.136-143
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• 2019

This study investigates the effect of denitrified biofloc water on changes in the water quality parameters and the physiological characteristics of shrimps. Biofloc rearing water contains a large number of microorganisms and can rapidly stabilize the water quality and energy saving if reusable due to high water temperatures. Rearing water contain floating bacteria with both aerobic and anaerobic bacteria. Therefore, when the carbon source is added in limited air supply, the anaerobic state is activated and the denitrification process is possible. In this study, the denitrification water had the following properties: ammonia (6.9 mg L^-1), nitrite (0.3 mg L^-1), nitrate concentration (9.2 mg L^-1), high pH (8.42) and alkalinity (590 mg L^-1). The experimental group consisted of seawater (SW, control), a mixture of Seawater and denitrified biofloc water (DNW) in the ratio of 3:1, 1:1 and DNW only. All experiments were done in triplicate. As a result, the survival rate never changed even when 100% of the denitrification water was utilized. However, a body fluid analysis showed that creatine and BUN were increased due to index of stress and the tissue damage resulting from the high denitrified water content. Body fluid ions (Na⁺, K⁺, and Cl^-) significantly decreased as the denitrified water content increased. It was recommended that the denitrification water be mixed with a certain ratio (less than 50%) in the future as it may affect the osmotic pressure control in shrimps.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.181-188
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• 2009

Pt catalyst was adsorbed on Carbon nanofiber (CNF) by modified polyol method after acid treatment of the carbon support with $HNO_3$ and $H_{2}SO_{4}$. As the time for acid treatment increases, more oxygen functional groups on carbon surface were produced which improve the loading amount and dispersion of Pt catalyst on carbon supports. In order to inspect the effect of CNF acid treatment time on electrochemical corrosion, constant potential of 1.4 V was applied to a single cell for 30 min and the amount of $CO_2$ emitted was monitored with on-line mass spectrometry. According to the results of our experiment, more $CO_2$ was produced with Pt/ oxidized-CNF catalyst in compared to that with unoxidized-CNF. Increasing acid treatment time also induces the more $CO_2$ emission. Besides, performance degradation after corrosion test expanded with severer carbon corrosion. From the observed results, it can be concluded that the acid treatment of CNF is beneficial to catalyst loading, but it also is a significant factor declining the fuel cell durability by accelerating electrochemical oxidation of carbon support.

• 한국해양학회지
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• v.22 no.3
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• pp.207-215
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• 1987

The Keum River Estuary was investigated two times in April and July, 1986, to study process controlling chlorophyll distribution in estuarine waters. During the surveys, distribution patterns were studied for chlorophyll-a, nutrients, ph, SPM (Suspended Particulate Matter), DO (Dissolved Oxygen), temperature, salinity, etc. During April survey(low-discharge period), sea water penetrated to Kangkyung, about 35km upstream from the constructing weir, while in July (high-discharge period) only to 3 km upstream from the weir,In April SPM showed very high concentrations (500mg/l)on the average. But very low concentrations(about10mg/l)were observed in July due to high discharge of fresh water.Chlorophyll-a concentrations showed large variations both in time and space :much higher concentraations in July than in April and sharp decrease in concentrations at the fresh water-sea water interface (April:$6.5\mu\textrm{g}/{\ell}$ for fresh waters and 41.4\mu\textrm{g}/{\ell}$ forestuarine waters). Differebce ub chlorophyll-a concentrations for these two surveys appear to be caused mainly by the difference in effectiveness of penetrating lights controlled by SPM in the waters. Sharp decrease in chlorophll-a at the fresh water-sea water interface is believed to be resulted from mass mortality of fresh water phytoplankton caused by changes in osmotic pressure in the region. Observations in the same regions such as increase in AOU(Apparent Oxygen Utilization)and ammonia, decrease in PH,probably resulted through decomposition processes of dead planktons,furtuer support the idea.

• Journal of the Korean Chemical Society
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• v.31 no.6
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• pp.491-497
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• 1987

$ThO_2-Tm_2O_3$ (TDT) solid solutions containing 1,3,5,8,10, and 15 mol% $Tm_2O_3$ were synthesized from spectroscopically pure $ThO_2$ and $Tm_2O_3$ polycrystalline powders. The TDT solid solutions were indentified to the fluorite structure by the X-ray powder technique. The values of the lattice parameter were decreased with increasing amount of $Tm_2O_3$ incorporated. But, there was no linearity for the samples containing 8, 10, and 15 mol% $Tm_2O_3$. It was concluded that these samples became incomplete solid solutions. From the intensity analyses of X-ray diffraction patterns, the residual factor was found below 0.13 even for the 15 mol% TDT system. lt was confirmed from the DTA and TGA analyses that any phase transitions did not occur under the experimental condition executed. Comparing the pycnometric density with the lattice parameter obtained from XRD, it was suggested that the predominant defect model be an oxygen vacancy.