• Journal of Life Science
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• v.22 no.7
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• pp.863-870
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• 2012

Rhodopsin, a dim light photoreceptor, has been regarded as one of the model systems for the structural and functional study of G protein-coupled receptors (GPCRs). Constitutively active mutant GPCRs leading to the activation of heterotrimeric GDP/GTP-binding protein signaling in the absence of ligand binding are of interest for the study of the activation mechanism in GPCRs. The present study focused on the opsin mutant E134Q/M257Y, which showed a moderate level of constitutive activity and the formation of two distinct rhodopsin chromophores with absorption maxima of 500 nm and 380 nm, depending on the presence of an inverse agonist, 11-cis-retinal, and an agonist, all-trans-retinal, respectively. Reconstitution of the mutant rhodopsin upon incubation with different ratios of 11-cis-retinal and the all-trans-retinal, as well as upon sequential binding of the two retinals, indicated its preferential binding to 11-cis-retinal. The thermal stability of the 11-cis-retinal-bound form of the E134Q/M257Y mutant was lower than that of the mutants containing a single replacement but higher than that of the all-trans-retinal-bound forms. The mutant also showed a lower stability in its opsin state as compared with that of the wild-type opsin but had little effects on the binding affinity to 11-cis-retinal. Information obtained in this study will be helpful for analyzing the structural changes associated with the activation of rhodopsin and GPCRs.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.1
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• pp.1-6
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• 1977

Fifteen soils including volcanic ash, acid sulfate and degraded saline soils were investigated for Languir adsorption isotherm of ammonium using $NH_4H_2PO_4$. The results are as follows. Languir adsorption maxima of ammonium (LAMA) ranged from 2.4me/100g soil to 12.3 and the average was 5.3. Initial concentration of 30 to 60 or 40 to 80 ppm(as N) appears to be suitable for LAMA measurement. There were two LAMA in some soils. Difference between adsorption constants (bonding energy) was mostly greater than that between LAMA. LAMA ranged from 9.4% to 72% of cation exchange capacity and average was 47%. It did not show any clear tendency with CEC, pH, organic matter content, base saturation percent, P, K, Ca, Mg, Na and Si. Except volcanic ash soils which were grouped into two groups according to ammonium adsorption LAMA was significantly (r=0.951 at 1%) correlated with adsorption at 200ppm. This single concentration seems suitable for LAMA measurement. Probable mechanism of ammonium adsorption was discussed, in which the associated anions were combined with iron and aluminum and then ammonium was bound to phosphorus. Applicability of Langmuir adsorption isotherm model to the soils under field condition was also discussed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1054-1065
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• 1993

A computer simulation is performed on the effectiveness of the active minimization of harmonically excited enclosed sound fields for producing global reduction in the amplitude of the pressure fluctuations. In this study for the appreciable reductions in total time averaged acoustic potential energy, $E_{pp}$, the transducer location strategies for three dimensional active noise control is presented based on a state space modal which approximates the closed acoustic field.In this study, the above theoretical basis is used to investigate the application of active control to sound fields of low modal density. By the used of room-like 3-dimensional rectangular enclosure it is demonstrated that the reductions in $E_{pp}$ can be achieved by using a single secondary source, provided that the source is placed within the half a wavelength from the primary source and placed away from nodal line of the sound field. Concerning the reductions in $E_{pp}$ by minimzing the pressure in sound fields by the use of 3-dimensional rectangular enclosure, the effects of the number of sensors and the locations of these sensors are investigated. When a few modes dominate the response it is found that if only a limited number of sensors are located away from nodal line and located at the pressure maxima of the sound field such as at each corner of a rectangular enclosure.

• Bulletin of the Korean Chemical Society
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• v.26 no.12
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• pp.1946-1952
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• 2005

New group 15 organometallic compounds, M$(phenanthrenyl)_3$ (M = P (1), Sb (2), Bi (3)) have been prepared from the reactions of 9-phenanthrenyllithium with $MCl_3$. A reaction of 9-(diphenylphosphino)phenanthrene with 2,6-diisopropylphenyl azide led to the formation of (phenanthrenyl)${(Ph)}_2P$=N-(2,6-$^iPr_2C_6H_3$) (4). The crystal structures of 2 and 4 have been determined by single-crystal X-ray diffractions, both of which crystallize with two independent molecules in the asymmetric unit. Compound 2 shows a trigonal pyramidal geometry around the Sb atom with three phenanthrenyl groups being located in a screw-like fashion with an approximately $C_3$ symmetry. A significant amount of CH- -$\pi$ interaction exists between two independent molecules of 4. The phosphorus center possesses a distorted tetrahedral environment with P-N bond lengths of 1.557(3)$\AA$ (P(1) N) and 1.532(3)$\AA$ (P(2)-N), respectively, which are short enough to support a double bond character. One of the most intriguing structural features of 4 is an unusually diminished bond angle of C-N-P, attributable to the hydrogen bonding of N(1)-H(5A) [ca. 2.49$\AA$ between two adjacent molecules in crystal packing. The compounds 1-3 show purple emission both in solution and as films at room temperature with emission maxima ($\lambda_{max}$) at 349, 366, and 386 nm, respectively, attributable to the ligand centered $\pi$ $\rightarrow$ $\pi^\ast$ transition in phenanthrene contributed by the lone pair electrons of the Gp 15 elements. Yet the nature of luminescence observed with 4 differs in that it originates from $\pi$ (diisopropylbenzene)-$\pi^\ast$ (phenanthrene) transitions with the $\rho\pi$contribution from the nitrogen atom. The emission maximum of 4 is red-shifted ranging 350-450 nm due to the internal charge transfer from the phenanthrenyl ring to the N-arylamine group as deduced from the ab initio calculations.

• Phonetics and Speech Sciences
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• v.5 no.1
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• pp.109-121
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• 2013

This study examined several kinematic properties of the primary articulator (the tongue dorsum) and the supplementary articulator (the jaw) in the articulation of the voiceless velar stop (/k/) within nonassimilating contexts. We examined in particular the spatiotemporal properties (constriction duration and constriction maxima) from the constriction onset to the constriction offset by analyzing a velar (/k/) followed by the coronal fricative (/s/), the coronal stop (/t/), and the labial (/p/) in across-word boundary conditions (/k#s/, /k#t/, and /k#p/). Along with these measurements, we investigated intergestural temporal coordination between C1 and C2 and the jaw articulator in relation to its coordination with the articulation of consonant sequences. The articulatory movement data was collected by means of electromagnetic midsagittal articulometry (EMMA). Four native speakers of Seoul Korean participated in the laboratory experiment. The results showed several characteristics. First, a velar (/k/) in C1 was not categorically reduced. Constriction duration and constriction degree of the velar (/k/) were similar within nonassimilating contexts (/k#s/=/k#t/=/k#p/). This might mean that spatiotemporal attributes during constriction duration were stable and consistent across different contexts, which might be subsequently associated with the nontarget status of the velar in place assimilation. Second, the gestural overlap could be represented as the order of /k#s/ (less) < /k#p/ (intermediate) < /k#t/ (more) as we measured the onset-to-onset lag (a longer lag indicated shorter gestural overlap.). This indicates a gestural overlap within nonassimilating contexts may not be constrained by any of the several constraints including the perceptual recoverability constraint (e.g., more overlap in Front-to-Back sequences compared to the reverse order (Back-to-Front) since perceptual cues in C1 can be recovered anytime during C2 articulation), the low-level speech motor constraint (e.g., more overlap in lingual-nonlingual sequences as compared to the lingual-lingual sequences), or phonological contexts effects (e.g., similarity in gestural overlap within nonassimilating contexts). As one possible account for more overlap in /k#t/ sequences as compared to /k#p/, we suspect speakers' knowledge may be receptive to extreme encroachment on C1 by the gestural overlap of the coronal in C2 since it does not obscure the perceptual cue of C1 as much as the labial in C2. Third, actual jaw position during C2 was higher in coronals (/s/, /t/) than in the labial (/p/). However, within the coronals, there was no manner-dependent jaw height difference in C2 (/s/=/t/). Vertical jaw position of C1 and C2 was seen as inter-dependent as higher jaw position in C1 was closely associated with C2. Lastly, a greater gap in jaw height was associated with longer intergestural timing (e.g., less overlap), but was confined to the cluster type (/kp/) with the lingual-nonlingual sequence. This study showed that Korean jaw articulation was independent from coordinating primary articulators in gestural overlap in some cluster types (/k#s/, /k#t/) while not in others (e.g., /k#p/). Overall, the results coherently indicate the velar stop (/k/) in C1 was robust in articulation, which may have subsequently contributed to the nontarget status of the velar (/k/) in place assimilation processes.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.5
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• pp.475-489
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• 2010

In order to verify the enhancement of ozone and carbon monoxide (CO) during springtime in East Asia, we investigated weather conditions and data from remote sensors, air quality models, and air quality monitors. These include the geopotential height archived from the final (FNL) meteorological field, the potential vorticity and the wind velocity simulated by the Meteorological Mesoscale Model 5 (MM5), the back trajectory estimated by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, the total column amount of ozone and the aerosol index retrieved from the Total Ozone Mapping Spectrometer (TOMS), the total column density of CO retrieved from the Measurement of Pollution in the Troposphere (MOPITT), and the concentration of ozone and CO simulated by the Model for Ozone and Related Chemical Tracers (MOZART). In particular, the total column density of CO, which mightoriginate from the combustion of fossil fuels and the burning of biomass in China, increased in East Asia during spring 2000. In addition, the enhancement of total column amounts of ozone and CO appeared to be associated with both the upper cut-off low near 500 hPa and the frontogenesis of a surface cyclone during a weak Asian dust event. At the same time, high concentrations of ozone and CO on the Earth's surface were shown at the Seoul air quality monitoring site, located at the surface frontogenesis in Korea. It was clear that the ozone was invaded by the downward stretched vortex anomalies, which included the ozone-rich airflow, during movement and development of the cut-off low, and then there was the catalytic photochemical reaction of ozone precursors on the Earth's surface during the day. In addition, air pollutants such as CO and aerosol were tracked along both the cyclone vortex and the strong westerly as shown at the back trajectory in Seoul and Busan, respectively. Consequently, the maxima of ozone and CO between the two areas showed up differently because of the time lag between those gases, including their catalytic photochemical reactions together with the invasion from the upper troposphere, as well as the path of their transport from China during the weak Asian dust event.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.4
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• pp.289-297
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• 1999

Concentrations of total dissolved free amino acids (DFAAs) in the northeast Pacific Ocean $9^{\circ}54'-10^{\circ}27'N$, $131^{\circ}43'-131^{\circ}53'W$) ranged from 15.9 to 1778.2 17M, and the average was 407.2 nM. Concentrations of DFAAs in surface mixed layers, ranged from 60.1 to 1411.9 nM, and the average was 535.2 nM. Seasonal thermoclines with maxima were formed between the depth of 50 to 150 m. DFAAs in this layer were varied in concentrations from 91.7 to 1778.2 nM, and the average was 588.5 nM. DFAAs below the seasonal thermoclines fluctuated from 15.9 to 384.2 nM, and the average was 175.1 nM. Consequently, in average relatively abundant DFAAs were observed in the subsurface layer than the deeper layer. DFAA vertical profiles and compositions of station A showed similar to station Band C. Glycine, alanine, glutamic acid, serine and valine were predominant accounting for more than 60% of total amino acids. Isoleucine, tyrosine, methionine and phenylalanine comprised only few percents of total DFAAs in the study area. In mole % of amino acid, according to characteristics of functional group of amino acid, aliphatic neutral accounted for 59% and aliphatic hydroxy 16%, acidic 12%, respectively. Although differences in DFAA concentrations with depth were observed, the amino acid composition and mole % of deeper layers in all stations were similar to those of subsurface layers. The results indicate that individual DtAAs remains invariably in water columns relative to the compositions and distributions of DFAAs in the study area, which may be the result of close coupling between microbial activity and their water solubility.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.31-36
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• 2001

The secondary election emission (SEE) yields for the thermally grown $SiO_2$ thin layers were measured by varying the thickness of the $SiO_2$ layer and the primary current. $SiO_2$ thin layers were thermally grown in a furnace at $930^{\circ}C$, whose thickness varied to be 5.8 nm, 19 nm, 43 nm, 79 nm, 95 nm, and 114 nm. When the $SiO_2$ layers were thinner than 43 nm, it was found that SEE curves followed the universal curve. However, for samples with a $SiO_2$ layer thicker than 79 nm, the SEE curves exhibited two maxima and the values of SEE yields were reduced. Additionally, as the current of primary electrons increased, the SEE yields were reduced. In this experiment, the maximum value of the SEE yield for $SiO_2$ layers was obtained to be 3.35 when the thickness of $SiO_2$ layer was 19 nm, with the primary electron energy 300 eV and the primary electron current 0.97 $\mu\textrm{A}$. The penetration and escape depth of an electron in the $SiO_2$ layers were calculated at the primary electron energy for the maximum value of the SEE yield and from these depths, it was calculated that the thickness of the $SiO_2$layer.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.2
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• pp.236-241
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• 1997

Inhibitory effects of several edible plant extracts against 3-hydroxy-3-methylglutaryl coenzyme A(HMG-CoA) reductase, a rate-limiting enzyme in the biosynthesis of cholesterol, were screened. Inhibition rates of $10{\sim}15%$ were observed with hot water extracts of Allium fistulosum, Allium sativum and Cucurbita maxima. Methanol extracts of Aster scaber, Allium sativum, Zingiber officinale, Oenanthe javanica and Angelica keiskei effectively reduced the enzyme activity with inhibition rates of $29{\sim}51%$. The methanol extract of Angelica keiskei was fractionated sequentially with chloroform, ethyl acetate and n-butanol. Of the fractions ethyl acetate fraction showed the highest inhibition against the enzyme. $Luteolin-7-O-{\beta}-D-glucoside$ and hyperoside isolated from the ethyl acetate fraction of Angelica keiskei inhibited the enzyme activity by 65.5% and 14.8%, respectively, at the concentration of $30{\mu}M$.

• The Korean Journal of Mycology
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• v.15 no.1
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• pp.29-37
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• 1987

Cellulolytic mocrooganisms were isolated from the cellulose-cultural properties. Among them, Aspergillus clavatus with the highest cellulase activity was identified by the morphological characteristics and it's enzyme activities were compared on the various cultural conditions. It was found that the induction of carboxymethylcellulase(CMCase), avicelase and salicinase in CMC liquid media showed the highest enzyme acitivity on five day's cultivation at $30^{\circ}C$ and thereafter their activities were gradually decreased with time. After crude extracellular enzymes precipitated with the 70% saturated ammonium sulfate solution were dialyzed with 20 mM acetate buffer pH 6.0, each crude enzyme was examined. The optimal activities of CMCase and avicelase were both found to be at $50^{\circ}C$ and pH 6.0. Their thermal stability was appeared at the $50^{\circ}C$. CMCase and avicelase had the maxima activities with 1.5% and 2.2% substrate concentration, respectively. The concentration of 5 mM $Mg^{++}$ or $Ca^{++}$ was found to have a maximum cellulase activity and its activity was inhibited with more than 5 mM $Cu^{++}$ and $Zn^{++}$ concentration. Cellulase activity was also inhibited sensitively by the inhibitors such as 2-mercaptoethanol, iodine and sodium azide.