• Journal of Soil and Groundwater Environment
• /
• v.22 no.3
• /
• pp.27-41
• /
• 2017

This study dealt with the characteristics and the interrelations of hydrogeological parameters such as hydraulic conductivity, dispersivity and effective porosity of unconsolidated sediments for providing the basic data necessary for the planning of the management and preservation of groundwater quality in the Nakdong River Delta of Busan City, Korea. Groundwater quality in this area has been deteriorated due to seawater intrusion, agricultural fertilizer and pesticide, industrial wastewater, and contaminated river water. The physical properties (grain size distribution, sediment type, sorting) and aquifer parameters (hydraulic conductivity, effective porosity, longitudinal dispersivity) were determined from grain size analysis, laboratory permeability test and column tracer test. Among 36 samples, there were 18 Sand (S), 7 Gravelly Sand (gS), 5 Silty Sand (zS), 5 Muddy Sand (mS), and 1 Sandy Silt (sZ). Hydraulic conductivity was determined through a falling head test, and ranged from $9.2{\times}10^{-5}$ to $2.9{\times}10^{-2}cm/sec$ (0.08 to 25.6 m/day). From breakthrough curves, dispersivity was calculated to be 0.35~3.92 cm. Also, effective porosity and average linear velocity were obtained through the column tracer test, and their values were 0.04~0.46 and 1.06E-04~6.49E-02 cm/sec, respectively. Statistical methods were used to understand the interrelations among aquifer parameters of hydraulic conductivity, effective porosity and dispersivity. The relation between dispersivity and hydraulic conductivity or effective porosity considered the sample length, because dispersivity was affected by experimental scale. The relations between dispersivity and hydraulic conductivity or effective porosity were all in inverse proportion for all long and short samples. The reason was because dispersivity was in inverse proportion to the groundwater velocity in case of steady hydrodynamic dispersion coefficient, and groundwater velocity was in proportion to the hydraulic conductivity or effective porosity. This study also elucidated that longitudinal dispersivity was dependent on the scale of column tracer test, and all hydrogeological parameters were low to high values due to the sand quantity of sediments. It is expected that the hydrogeological parameter data of sediments will be very useful for the planning of groundwater management and preservation in the Nakdong River Delta of Busan City, Korea.

• Economic and Environmental Geology
• /
• v.45 no.1
• /
• pp.23-30
• /
• 2012

Major ions and nitrogen isotopic analyses were performed to determine the geochemical characters and to identify the source of nitrate of the shallow groundwater around agricultural field in the Youngdong area. The pH value of groundwater ranges from 60. to 8.2 (pH 7.2, mean). The average of EC, Eh and DO is 369 ${\mu}S/cm$ (70~729 ${\mu}S/cm$), 165.6 mV (29~383.2 mV), 4.3 mg/L (1.8~8.0 mg/L) respectively. The ion concentraion of groundwater was in the order of $Ca^{2+}$>$Na^{2+}$>$Mg^{2+}$>$K^{2+}$ and ${HCO_3}^-$>${NO_3}^-$>${SO_4}^{2-}$>$Cl^-$>$F^-$. Most of groundwater is Ca-$HCO_3$ type. The groundwater was affected by water-rock interaction in the shallow depth. Some groundwater is Ca-Cl or Na-$HCO_3$ (2.5%) type that was due to agricultural activities. The $NO_3$_N concetration of grondwater range from 10.2 mg/l to 26.9 mg/l, which show that this area is under nitrate pollution. ${\delta}^{15}N-NO_3$ value of the groundwater is the origins of are a combination of animal wastes and man-made fertilizers.

• Journal of the Korean Chemical Society
• /
• v.41 no.3
• /
• pp.117-122
• /
• 1997

On the basis of our previous paper[Bull. Korean Chem. Soc. 1995, 16, 1015], the relative stability, ionization potential, and chemical reaction of the neutral and multiply charged $C_{60}$n ions(n=3+ to 6-) have been investigated by the semi-empirical MNDO method. $C_{60}^{1-}$ has the highest stability. The ionization potential values of the $C_{60}$ ions range from 15.31 eV of $C_{60}^{2+}$ to -13.01 eV of $C_{60}^{6-}$. These values show a linear relationship according to charges. The average IP per charge is 3.15 eV from our calculations and 3.22 eV from the linear function of IP. A charge- or electron-transfer reaction of $C_{60}^{n+}$ will only occur if the ionization potential of any guest molecule is lower than the electron affinity of the host $C_{60}^{n+}$. If the energy gap between ionization potential and electron affinity, ${\Delta}_{IP-EA}$, is high, charge-transfer reactions arise by the charge-controlled effect. However, if ${\Delta}_{IP-EA}$ is low, electron-transfer reactions arise by the frontier-controlled effect.

• 한국해양학회지
• /
• v.19 no.2
• /
• pp.153-162
• /
• 1984

This study was conducted to interpret the relations between the polychaete community and its environments in Kwangyang Bay during July, 1982. The type of sediments in the study area varies from sand to clay and the organic content obtained by ignition was in the ranges of 0.3% to 15.4%. The polychaetes which occurred at 25 stations comprised 70 species representing 63 genera and had an average density of 490 animals/m$\^$2/. The most abundant species were Lagis bocki (20%), Lumbrineris longifolia (10%), Chohe teres (7%), and Sternaspis scutata (5%). The polychaete populations show the highest density in muddy sand sediments and have a tendency to decrease their abundance in finer sediments such as bud and clay. The individual numbers of each feeding type show the same tendency. Kwangyang Bay consists of three distinct characteristic communities, representing different physical and biological factors: delta community, muddy flat community and channel community. Delta community has very poor organisms and seems to be determined by physical factors such as tidal current, and by sediment conditions and seems to be determined by physical factors such as tidal current, and by sediment conditions and by the food availability. Muddy flat community shows more diverse and higher abundance than delta community but seems to be impoverished by the stress of oxygen deficiency in sediments. Channel community has the highest density in the study area and comprises more various feeding types. This is probably due to the supply of allochthonous materials from the Seomjin River and offshore as food, the heterogeneous sediments and some biological interactions within habitats.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.14 no.4
• /
• pp.359-364
• /
• 1985

Being used the three kinds of aqueous solution of tobacco extracts as a new experimental material, experiment and theoretical analysis are performed. Measurements are made with a apparatus designed and constructed by the author.The average diameter of the ice crystals is 0.04-0.1cm between 0.2 and $0.6^{\circ}C$ of the subcooling temperature of the solution. The growth rate of ice crystals in direction of axies A, $V_a$ is in proportion to the subcooling temperature, viz; $v_a=0.058{\Delta}t_b,\;where\;{\Delta}t_b<0.1^{\circ}C$ The growth rate of ice crystal have to be considered not only the mass diffusion and the heat transfer of rate controlling but also the process in ice crystallization. The growth rate of ice crystal is found to be independent on the concentration of the solution and a diameter of ice crystal.

• Korean Chemical Engineering Research
• /
• v.43 no.6
• /
• pp.740-744
• /
• 2005

Perovskite-type oxide $La_{1-x}Sr_xCo_{1-y}Fe_yO_{3-{\delta}}$ sols were prepared by sol-gel method using $La(NO_3)_3{\cdot}xH_2O$, $Sr(NO_3)_2$, $Co(NO_3)_2{\cdot}6H_2O$ and $Fe(NO_3)_3{\cdot}9H_2O$ as starting materials. The properties of the perovskite-type oxide sols were investigated by viscometer, FT-IR, TG-DTA and XRD. The prepared sols showed 1.16 cp in average viscosity, and a strong acidic condition of pH 0.5, irrespective of composition of the starting materials. The viscosity of sols at the same volume decreases, but the gelation time of sols, at which the sol viscosity increases rapidly, increases when increasing La concentration in composition of starting materials.

• Economic and Environmental Geology
• /
• v.43 no.1
• /
• pp.43-52
• /
• 2010

The geochemical and nitrogen isotopic analyses for shallow groundwater of Ogcheon area were carried out to characterize the geochemical characteristics of the groundwater and to identify the source of nitrate. Groundwater shows a neutral pH to weakly alkalic condition with pH values ranging from 6.9 to 8.4. The average of EC, Eh and DO is $344.2\;{\mu}s/cm$, 195 mV, 4 mg/L, respectively. According to piper diagram, chemical composition of groundwater is dominantly characterized by Ca-$HCO_3$ type. On the other hand, groundwater type in the study area include Ca-Cl+$NO_3$ type that were highly influenced by agricultural activities. $NO_3$-N concentration of the collected samples(n=45) range from 12.4 to 34.2 mg/l. These data show that the $NO_3$-N concentration exceeds Korea Drinking Water Standard (10 mg/l). The $\delta^{15}N-NO_3$ values range from $2.7^{\circ}/_{\circ\circ}$ to $18.8^{\circ}/_{\circ\circ}$. The enrichments of heavy isotope in the groundwater indicate that major origin of nitrate pollution were associated with animal and human waste. Also the denitrification may have partly contributed as one of the sources of nitrogen.

• Korean Journal of Materials Research
• /
• v.3 no.5
• /
• pp.497-504
• /
• 1993

Effects of $Ta_2O_5,ZrO_2$ and $SiO_2$ addition on magnetic properties of 0.02wt%$Bi_2O_3$ and 0 . 0 5 wt%$CaCO_3$ doped Mn-Zn ferrites(58.5mol% $Fe_2O_3$, 25.5 mol% ZnO) were investigated. E:lectrlcal resistivity and magnetic properties such as the initial permeability($\mu_i$), loss factor(tan$\delta$), coercive force Hc(m0c) were measured. With lncreasing $Ta_2O_5$ and $ZrO_2$ addition, the following effects were observed: I ) Decreasing of the average grain size; 2) lncreasing of the electrical resistivity and initial permeability; 3) Ilecreasmg of loss factor values. (very low loss esprcially at high frequency region) ; 4 ) Fine and uniform microsrructures were obtamed at O.lwt% nddecl samples. In case of $SiO_2$ addition, anomalous grain growth and degradation of magnetic properties were observed. The obtained maximum initial permeability value was 6260 at IOkHz. $25^{\circ}C$ from 0.02wt%$Bi_2O_3$. 0.05wt%$CaCO_3$, 0.lwt%$Ta_2O_5$ added sample, the corresponded relative loss factor (tan$\delta /\mu_i$)for the sample was $4.2 \times 10^{-6}$.

• Korean Journal of Clinical Pharmacy
• /
• v.8 no.2
• /
• pp.107-112
• /
• 1998

Lovastatin is a lipid lowering agent for the treatment of hypercholesterolemia and belongs to a new class of pharmacologic compounds called the 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors. By competitively inhibiting HMG CoA reductase, lovastatin disrupts the biosynthesis of cholesterol in hepatic and peripheral cells and increases the synthesis of high-density-lipoprotein HDL) receptors. Following oral administration, the lactone ring of lovastatin is hydrolysed to the active inhibitor of HMG CoA reductase, lovastatin acid. Lovastatin is known to have poor oral absorption and wide individual variation. In this study, bioequivalence test of two lovastatin formulations, the test drug ($Lovaload^{TM}$, Chong Kun Dang Pharmaceutical Co.) and the reference drug ($Mevacor^{TM}$, Chung Wae Pharmaceutical Co.) were conducted according to the guidelines of Korea Food and Drug Administration (KFDA). A total of 18 healthy male volunteers, $31.90\pm3.60$ years old and $72.17\;7.88$ kg of body weight in average, were evaluated in a randomized crossover manner with a 2-week washout period. Concentrations of lovastatin acid in plasma were measured upto 12 hours following a single oral administration of eight tablets (20 mg of lovastatin per tablet) by high-performance liquid chromatography with UV detection at 238 nm. The area under the concentration-vs-time curve from 0 to 12 hours $(AUC_{0-12h})$ was calculated by the trapezoidal summation method. The statistical analysis showed that there are no significant differences in $AUC_{0-12h),\;C_{max}\;and\;T_{max}$ between the two formulations ($6.72\%,\;1.52\%,\;and\;0.88\$, respectively). The least significant differences between the formulations at $\alpha$=0.05 were less than $20\%\;(11.65\%,\;19.73\%,\;and\;14.81\%\;for\;AUC_{0-12h},\;C_{max}\;and\;T_{max}$, respectively). The $90\%$ confidence intervals for these parameters were also within $\pm20\%\;(-1.50{\leq}{\delta}{\leq}15.00$, $-12.50{\leq}{\delta}{\leq}15.50,\;and\;-9.64{\leq}{\delta]{\leq}11.40{\leq}\;for\;\;AUC_{0-12h}$ ,$C_{max}\;and\;T_{max}$, respectively). In conclusion, the new generic product $Lovaload^{TM}$ was proven to be bioequivalent with the reference drug.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.12
• /
• pp.2755-2760
• /
• 2010

The moxibustion therapy of orient medical is well known. Moxibustion method is used to burning moxibustion. The variation factors of the moxibustion stimulation for body can be applied to the electronic moxibustion method. This study is to analyze and examine the electroencephalogram(EEG) variations for moxibustion stimulation. In experiment, we divided six healthy male subjects into two same sized groups : with and without stimuli. The given stimuli are the moxibustion for CV4(Kwan-Won), CV8(Shin-Guel), and CV12(Jung-wan) acupuncture points. We have analyzed the power spectrum for ${\alpha}$, ${\beta}$, ${\delta}$, ${\Theta}$ waves and the average EEG variation level and each channels variation level of EEG. The result was that the moxibustion stimulation decreased the EEG levels of parietal lobe(ch 2, 3, 6, 7) according to the somatosensory system. And the apparent different points are that mild-heat($42{\sim}44^{\circ}C$) stimulation generating ${\alpha}$-wave is increased and ${\beta}$-wave is decreased, also slight-hot($45{\sim}48^{\circ}C$) stimulation made ${\alpha}$-wave decrease and ${\beta}$-wave increase for occipital lobe(ch 4,8) on the simulation group.