• Membrane Journal
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• v.34 no.1
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• pp.10-19
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• 2024

The bipolar membrane is an ion exchange membrane consisting of a cation exchange layer, an anion exchange layer, and an interface layer, and is a membrane that generates protons and hydroxide ions based on water dissociation characteristics. Using these properties, research is being conducted in various application fields such as the chemical industry, food processing, environmental protection, and energy conversion and storage. This paper investigated the concept of bipolar membrane, water dissociation mechanism, and water dissociation catalyst to provide a comprehensive understanding of bipolar membrane technology, were investigated. Lastly, we also investigated the bipolar membrane process that has been recently applied to energy technology.

• Journal of The Korean Society of Grassland and Forage Science
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• v.28 no.4
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• pp.331-340
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• 2008

This study was conducted to investigate the effects of the type of swine manure on herbage productivity, the properties of soil and environmental pollution in mixed grassland. The field experiment was carried out on Livestock Breeding Station, Chonbuk in Korea from Nov. 2002 to Nov. 2005. Experimental plots were consisted of the types of swine manure, such as additional swine manure fermented with sawdust (SMFWS)+urea 50% and swine slurry (SS)+urea 50%. And then, chemical fertilizer (Urea) is used as control. DM yields of herbage were not different between chemical fertilizer and the type of swine manure. Feed values (CP, NDF, ADF, TDN) were not different between chemical fertilizer and swine manure treatments. After finishing with the experiment, Organic matter contents in soil increased. Organic matter, available phosphorous and Ca contents in swine manure treatment were higher than those of chemical fertilizer (p<0.05). $NO_3$-N and $NH_4$-N concentrations in leaching water in the mixed grassland was hardly influenced by application of swine manure and urea, whereas $NO_3$-N and $NO_3$-N levels in leaching water were less than 5 ppm.

• Journal of the Korean Chemical Society
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• v.44 no.3
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• pp.220-228
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• 2000

This study deals with the water qualities of Dalgi mineral spring in Cheongsong district.Water samples which were taken from upper, middle and bottorn spring sites were tested for twenty eight important water quality items including minerals, essential and/or toxic trace elements, and the analytical items to affect the taste of mineral water, seasonally from May 1999 to February 2000 The results obtained wereas follows:Each spring site showed much difference in major items. Bottom spring water showed higher value of Mg and Na than others. Middle spring water showed the highest value in all of the items except Mg and Na. The concentration of Hardness, Fe and Mn in mineral water were over than the normal standard for drinking water, but these items are not specified for the mineral water. As, Cd, $Cr^{6+}$ and Hg were not found and Pb was found ln trace level. All of the items proved nearly constant during the four seasons except water temperature. The contribution of mineral water to the nutrition of human was calculated in order to investigate the health effect of drinking water on the bases of Required Daily Allowance,one liter of water drinking and the mineral concentration of the bottom spring. The percentage of consumable minerals of Ca, Mg, Na, K, Mn,Zn and Fe were 35.05,36.43,5.88∼10.63,0.19∼0.57,21.86∼43.72,0.65, and 95.l respectively. This means Dalgl mineral water is pIenty of iron mineral. The K and O indexes of mineraI water appeared to be good for healthy and delicious water.

• Journal of Environmental Health Sciences
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• v.43 no.1
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• pp.77-86
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• 2017

Objectives: The purpose of this study was to compare permeation characteristics in three skin types using oil-soluble benzoic acid and water-soluble caffeine after method condition optimization based on OECD guideline 428. Methods: A Franz diffusion cell, a reliable alternative method for skin permeation, was used. One-milliliter samples were taken and immediately replaced with fresh solution in the receptor chamber at regular time intervals (1, 2, 4, 7, 10 and 24 hr). The amount of test substances was measured by LC-MS/MS. Results: The permeation rate increased dose-dependently, and the permeation orders were $KeraSkin^{TM}$ > hairless mouse full skin > human cadaver epidermis for skin types, and benzoic acid solution > caffeine solution > benzoic acid cream > caffeine cream for type of test materials. Conclusion: According to the definitions of Marzulli, benzoic acid and caffeine would be classified as 'fast' and 'moderate' compared with the permeation of other chemical species. The setting conditions and permeation characteristics performed in this study are expected to contribute to future permeation studies.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.6
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• pp.577-585
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• 2015

We fabricated multi-scale such as macro-, micro-, and multi-scale wrinkles by using repetitive volume dividing (RVD) method and thermal curing process. Also wrinkle surface was modified with coating of a self-assembled monolayer (SAM). We measured the contact angle of each wrinkled surface, and observed the behavior of droplets on sloping surface. Through experimental study, we found out that the contact angle was much higher in case of multi-scale and SAM coated wrinkles. And micro-scale wrinkle showed a high contact angle comparing with that of macro-scale wrinkle. Dynamic behaviors of a water droplet like sliding velocity on diverse wrinkled surfaces were dependent on their static contact angles. These results showed that hydro-dynamic characteristics were changed depending on the wrinkle structure and the material forming the wrinkle. These dynamic characteristics can be utilized in bio-chip, microfluidics, and many others in order to control easily chemical reactivity.

• Korean Journal of Ecology and Environment
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• v.38 no.4 s.114
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• pp.435-438
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• 2005

We observed the physical, chemical, and biological characteristics of an acidic lake, Lake Katanuma, from 1998 to 2002 at weekly or biweekly intervals, except during the winter. This volcanic lake has a dimictic thermal pattern. In summer, the volcanic heat supply at the lake bottom results in weak thermal stratification. In 1998, 1999, and 2002, short-term holomixis was observed during the stratification period, when the anoxic, hydrogen sulfide-rich water from the hypolimnion spread across the entire lake. In contrast, distinct short-term holomixis did not occur during the stratificatlon period in 2000 and 2001. However, the early onset of the autumn turnover in August 2000 and 2001 caused anoxic conditions to persist throughout the entire water column for more than 2 weeks. The anoxic and hydrogen sulfide-rich conditions affected population densities of chironomid larvae (Chironomus acerbiphilus) and planktonic algae (Chlamydomonas acidophila), both dominant species in Lake Katanuma. Thus, the interannual variations of limnological characteristics influenced the seasonal population changes of these species.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.3
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• pp.239-254
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• 2015

Little information on HUmic-Like Substances (HULIS) in ambient particulate matter has been reported yet in Korea. HULIS makes up a significant fraction of the water-soluble organic mass in the atmospheric aerosols and influence their water uptake properties. In this study 24-hr $PM_{2.5}$ samples were collected between December 2013 and October 2014 at an urban site in Gwangju and analyzed for organic carbon (OC), elemental carbon (EC), water-soluble OC (WSOC), HULIS, and ionic species, to investigate possible sources and formation processes of HULIS. HULIS was separated using solid phase extraction method and quantified by total organic carbon analyzer. During the study period, HULIS concentration ranged from 0.19 to $5.65{\mu}gC/m^3$ with an average of $1.83{\pm}1.22{\mu}gC/m^3$, accounting for on average 45% of the WSOC (12~ 73%), with higher in cold season than in warm season. Strong correlation of WSOC with HULIS ($R^2=0.91$) indicates their similar chemical characteristics. On the basis of the relationships between HULIS and a variety of chemical species (EC, $K^+$, $NO_3{^-}$, $SO_4{^{2-}}$, and oxalate), it was postulated that HULIS observed during summer and winter were likely attributed to secondary formation and primary emissions from biomass burning (BB) and traffics. Stronger correlation of HULIS with $K^+$, which is a BB tracer, in winter ($R^2=0.81$) than in summer ($R^2=0.66$), suggests more significant contribution of BB emissions in winter to the observed HULIS. It is interesting to note that BB emissions may also have an influence on the HULIS in summer, but further study using levoglucosan that is a unique organic marker of BB emissions is required during summer. Higher correlation between HULIS and oxalate, which is mainly formed through cloud processing and/or photochemical oxidation processes, was found in the summer ($R^2=0.76$) than in the winter ($R^2=0.63$), reflecting a high fraction of secondary organic aerosol in the summer.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.6
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• pp.577-585
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• 2014

Nanorod and particle shape $CeO_2$ were synthesized via hydrothermal process and precipitation method, respectively, and used as supports of Pt catalyst for water gas shift (WGS) reaction. Three different durations (12, 48, and 96h) for hydrothermal process were applied for the preparation of nanorod type $CeO_2$. 1.0 wt% of Pt was loaded on the prepared supports with incipient wetness method prior to the catalytic activity tests that were carried out at a GHSV of $95,541h^{-1}$, and a temperature range of 200 to $360^{\circ}C$. Varying duration of hydrothermal process led to the difference in physical characteristics of $CeO_2$ nanorods, such as aspect ratio, BET surface area, pore diameter, and pore volume. Consequently, the catalytic activities of Pt/$CeO_2$ nanorods were affected by the physical characteristics of the supports and appeared to be in the order of Pt/$CeO_2$(12) > Pt/$CeO_2$(48) > Pt/$CeO_2$(96). The comparison of the catalytic activities and results of the analysis (XPS, XRD, SEM, BET and TPR) for the supports revealed that the activity of the catalysts depends on chemical states of the Pt and the support materials in the temperature range that is lower than $280^{\circ}C$. However, the activity is rather dependent on the physical characteristic of the supports because the increased gas velocity limits the mass transfer of reactants in micropores of the supports.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.17-18
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• 2011

Plasma in liquid phase has attracted great attention in the last few years by the wide domain of applications in material processing, decomposition of organic and inorganic chemical compounds and sterilization of water. The plasma in liquid is characterized by three main regions which interact each - other during the plasma operation: the liquid phase, which supply the plasma gas phase with various chemical compounds and ions, the plasma in the gas phase at atmospheric pressure and the interface between these two regions. The most complex region, but extremely interesting from the fundamental, chemical and physical processes which occur here, is the boundary between the liquid phase and the plasma gas phase. In our laboratory, plasma in liquid which behaves as a glow discharge type, is generated by using a bipolar pulsed power supply, with variable pulse width, in the range of 0.5~10 ${\mu}s$ and 10 to 30 kHz repetition rate. Plasma in water and other different solutions was characterized by electrical and optical measurements. Strong emissions of OH and H radicals dominate the optical spectra. Generally water with 500 ${\mu}S/cm$ conductivity has a breakdown voltage around 2 kV, depending on the pulse width and the repetition rate of the power supply. The characteristics of the plasma initiated in ultrapure water between pairs of different materials used for electrodes (W and Ta) were investigated by the time-resolved optical emission and the broad-band absorption spectroscopy. The deexcitation processes of the reactive species formed in the water plasma depend on the electrode material, but have been independent on the polarity of the applied voltage pulses. Recently, Coherent anti-Stokes Raman Spectroscopy method was employed to investigate the chemistry in the liquid phase and at the interface between the gas and the liquid phases of the solution plasma system. The use of the solution plasma allows rapid fabrication of the metal nanoparticles without being necessary the addition of different reducing agents, because plasma in the liquid phase provides a reaction field with a highly excited energy radicals. We successfully synthesized gold nanoparticles using a glow discharge in aqueous solution. Nanoparticles with an average size of less than 10 nm were obtained using chlorauric acid solutions as the metal source. Carbon/Pt hybrid nanostructures have been obtained by treating carbon balls, synthesized in a CVD chamber, with hexachloro- platinum acid in a solution plasma system. The solution plasma was successfully used to remove the template remained after the mesoporous silica synthesis. Surface functionalization of the carbon structures and the silica surface with different chemical groups and nanoparticles, was also performed by processing these materials in the liquid plasma.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.9
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• pp.597-603
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• 2012

To investigate the effects of weir construction on sediment characteristics of river bed, we conducted sediments sampling on the 9 locations near the weir, Kangchun, Yuju and Ipo in Namhan-River. Physical and chemical characteristics of sediments were analyzed by measuring particle size distribution, water content, Ignition loss, COD (Chemical Oxyzen Demand), TOC (Total Organic Carbon), TP (Total Phosphorus), SRP (Soluble Reactive Phosphorus) and TN (Total Nitrogen). Particle classification of all three weir sediments showed sandy loam that was caused by the river bed dredging. Due to the presence of weir, Ignition loss, COD, TOC, TP, SRP and TN showed similar trend such as the concentrations of upward weir had higher than those of downward weir. For the case of SRP concentration and C/N ratio, however, there is not much difference in the sediment characteristics compared to the those of sediments before weir construction. Therefore, It can be predicted that there are little effects of weir construction on sediment characteristics. However, weir construction could influence water quality of the river by controlling the transport and the accumulation of suspended materials from rainfall. Therefore, more intensive monitoring is required to examine the magnitude and patterns of sediment accumulation which could influence overlying water quality.