• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3777-3787
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• 2012

Three kinds of 3D isomorphous and isostructural coordination polymers, namely, $\{[Ln_2(PDA)_3(H_2O)_3]{\cdot}0.25H_2O\}_{\infty}$ (Ln = La(1), Sm(2), and Gd(3)) ($PDA^{2-}$ = pyridine-2,6-dicarboxylate anion) have been synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, thermal analyses and single crystal X-ray diffraction. In these MOFs, Ln(III) centers adopt eight-coordinated and nine-coordinated with the $N_1O_7$ and $N_2O_7$ donor sets to construct distorted trianglar dodecahedron geometry and tricapped trigonal prism configurations, respectively. Based on the building block of tetranuclear homometallic $Ln_4C_4O_8$ unit (16-membered ring), 1-3 are connected into highly ordered 2D sheets via O-C-O linkers and further constructed into 3D architectures through hydrogen bonds. Crystallographic parameters suggest that the lanthanide contraction effect exist in these coordination polymers. Luminescent properties of the lanthanide-based MOFs (metal-organic frameworks) have been measured at room temperature, which reveal that they presenting ionselective characters toward certain metals, such as $Mg^{2+}$, $Cd^{2+}$ and $Pb^{2+}$ ions.

• Bulletin of the Korean Chemical Society
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• v.28 no.11
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• pp.1945-1950
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• 2007

Two fluorene-based conjugated copolymers containing hexyl-thiophene derivatives, PF-1T and PF-4T, were synthesized via the palladium-catalyzed Suzuki coupling reaction. The number-average molecular weights (Mn) of PF-1T and PF-4T were found to be 19,100 and 13,200, respectively. These polymers were soluble in common organic solvents such as chloroform, chlorobenzene, toluene, etc. The UV-vis absorption maximum peaks of PF-1T and PF-4T in the film state were found to be 410 nm and 431 nm, respectively. Electrochemical characterization revealed that these polymers have low highest occupied molecular orbital (HOMO) levels, indicating good resistance against oxidative doping. Thin film transistor devices were fabricated using the top contact geometry. PF-1T showed much better thin-film transistor performance than PF-4T. A thin film of PF- 1T gave a saturation mobility of 0.001-0.003 cm2 V?1 s?1, an on/off ratio of 1.0 × 105, and a small threshold voltage of ?8.3 V. To support TFT performance, we carried out DSC, AFM, and XRD measurements.

• Journal of Korean Society of Forest Science
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• v.90 no.6
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• pp.683-691
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• 2001

This study aimed to clarify the influencing factors of the mesopore ratio on a pore geometry of surface soil in mixed stands as an index of the water retention capacity. Twenty four factors including site conditions and soil properties were analyzed by spss/pc+ for the data collected from during March to October of 1995. The factors influencing the mesopore ratio(pF2.7) on the surface soil were as follows; mesopore ratio(pF2.7) on the B horizon soil, under vegetation coverage, organic matter contents of surface soil and F layer depth. And influencing factor on the ratio of mesopore in the soil surface was correlated with surface soil hardness and depth of 10cm soil hardness shows high negative significance. Also, multiple regression equations for mesopore ratio of the mesopore ratio of B horizon soil and organic matter contents shows high significance($R^2$; 0.84).

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.1
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• pp.159-165
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• 1995

A double-heterostructure mesa-stripe-geometry laser diode integrated with thermoelectric Peltier cooler has been designed and fabricated. Epi-layers have been grown by metal organic chemical vapor deposition(MOCVD) method. Peltier cooling effect has been measured for devices with a mesa width of 14$\mu$m and a cavity length of 380$\mu$m. The effects of thermoelectric cooling could be shown by measuring the optical output of the laser with the increase of the current in the thermoelectric cooler. While the input courrent of the laser was maintained at 250mA, the optical output was decreased from 4.8mW to 3.8mW due to heating, but with the thermoelectric cooler on the optical output power was recovered by more than 40%. The results show that the complicated cooling device is not needed since the cooling can be achevied by the developement of the fabrication processing.

• Proceedings of the Korean Environmental Health Society Conference
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• 2001.11a
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• pp.64-69
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• 2001

The present work provides a result from the preliminary experiment for hydrocyclone technology. In this work, local lake sediments and waste coal fly ash were used as test samples, prior to the application of hydrocyclone technology to the waste sludge thickening. A few cyclones based on the Rietema standard geometry were prepared. Chemical analysis of the sediments showed that more organic contaminants were in smaller particles. The experimental tests further showed that physical characteristics of particles, configuration of the cyclone and operation condition would affect the separation efficiency. The current results showed that small size cyclones might improve the separation and concentration of the lake sediments, and higher inlet velocity would increase the concentration rate of under flow and absolute concentration of sediment particles.

• Korean Journal of Organic Agriculture
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• v.23 no.4
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• pp.963-974
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• 2015

This study was conducted to determine the effects of organic vegetable cultivation on the soil physical properties in 33 farmlands under plastic greenhouse in Korea. We were investigated 5~8 farms per organic vegetable crops during the period from August to November 2014. The main cultivated vegetables were leafy lettuce (Lactuca sativa L.), Perilla leaves (Perilla frutescens var. Japonica Hara), cucumber (Cucumis sativus L.), strawberry (Fragaria ananassa L.) and tomato (Lycopersicon spp.). We have analyzed soil physical properties. The measured soil physical parameters were soil plough layer, soil hardness, penetration resistance, three soil phase, bulk density and Porosity. The measurement of the soil plough layer, soil hardness and penetration resistance were carried out direct in the fields, and the samples for other parameters were taken using the soil core method with approximately 20 mm diameter core collected from each organic vegetable field. Soil plough layer was average 36 cm and ranged between 30 and 50 cm, and slightly different depending on the sorts of vegetable cultivation. The soil hardness was $0.17{\pm}0.15{\sim}1.34{\pm}1.02$ in the topsoil, $0.55{\pm}0.34{\sim}1.15{\pm}0.62$ in the subsoil. It was not different between topsoil and subsoil, but showed a statistically significant difference between the leafy and fruit vegetables. Penetrometer resistance is one of the important soil physical properties that can determine both root elongation and yield. The increase in density under leafy vegetables resulted in a higher soil penetrometer resistance. Soil is a three-component system comprised of solid, liquid, and gas phases distributed in a complex geometry that creates large solidliquid, liquid-gas, and gas-solid interfacial areas. The three soil phases were dynamic and typically changed in organic vegetable soils under greenhouse. Porosity was characterized as range of $54.2{\pm}2.2{\sim}60.3{\pm}2.4%$. Most measured soils have bulk densities between 1.0 and $1.6gcm^{-3}$. To summarize the above results, Soil plough layer has been deepened in organic vegetable cultivation soils. Solid hardness (the hardness of the soil) and bulk density (suitable for the soil unit mass) have been lowered. Porosity (soil spatial content) was high such as a well known in organic farmlands. Important changes were observed in the physical properties according to the different vegetable cultivation. We have demonstrated that the physical properties of organic cultivated soils under plastic greenhouse were improved in the results of this study.

• Korean Journal of Materials Research
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• v.23 no.8
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• pp.453-461
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• 2013

Controlling the stick and slip motions of the contact lines in a confined geometry comprised of a spherical lens with a flat substrate is useful for manufacturing polymer ring patterns. We used a sphere on a flat geometry, by which we could control the interfaces of the solution, vapor and substrate. By this method, hundreds of concentric ring-pattern formations of a linear conjugated polymer, poly [2-methoxy-5-(2-thylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), were generated with excellent regularity over large areas after complete solvent evaporation. Subsequently, the MEH-PPV ring patterns played a role as a directed template to organize highly regular concentric rings of single-walled carbon nanotubes(SWCNTs); when a droplet of the SWCNT suspension in water was casted onto the prepared substrate, hydrophobic polymer patterns confined the water dispersed SWCNTs in between the hydrophilicized $SiO_2/Si$ substrate. As the solvent evaporated, SWCNT-rings were formed in between MEH-PPV rings with controlled density. Finally, we used a lift-off process to produce SWCNT patterns by the removal of a sacrificial polymer template with organic solvent. We also fabricated a field effect transistor using self-assembled SWCNT networks on a $SiO_2/Si$ substrate.

• Bulletin of the Korean Chemical Society
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• v.24 no.5
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• pp.605-609
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• 2003

The lower-order lithium organocyanocuprate compound, (THF)₃Li(NC)Cu($C_6$H₃-2,6-Mes₂) (1), and the bulky terphenyl Grignard reagent, Br(THF)₂Mg($C_6$H₃-2,6-Trip₂) (2), have been synthesized and structurally characterized both in the solid state by single crystal x-ray crystallography and in solution by multi-nuclear NMR and IR spectroscopy. The compound (1) was isolated as a monomeric contact ion-pair in which the C (organic ipso)-Cu-CN-Li atoms are coordinated linearly. The lithium has a tetrahedral geometry as a result of solvation by three THF molecules. The compound (1) is the first example of fully characterized monomeric lower order lithium organocyanocuprate. The bulky Grignard reagent (2) was also isolated as a monomer in which the magnesium, solvated by two THF molecules, has a distorted tetrahedral geometry. The crystals of (1) possess triclinic symmetry with the space group $P{\={1}}$, Z = 2, with a = 12.456(3) Å, b = 12.508(3) Å, c = 13.904(3) Å, α = 99.81°, β = 103.72(3)°, and γ = 119.44(3)°. The crystals (2) have a monoclinic symmetry of space group $P2_{1/C}$, Z = 4, with a = 13.071(3) Å, b = 14.967(3) Å, c = 22.070(4) Å, and β = 98.95(3)°.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.29-35
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• 1999

Soil structure and organic matter have been known to strongly affect water flow and solute transport, yet little information is available concerning soil hydraulic properties related to soil physical and chemical properties in the forest site. The purpose of this study was to quantify the spatial variability and spatial correlation of the measured parameter values from the plots established with the rainfall simulator on Japanese larch(Larix leptolepis) dominated site in Kwangju. Kyunggi-Do. Measurement of soil water flux and retention were made with the inherent soil texture, soil structure, and organic matter. The method was based on the observation that when water was applied at a constant rate to the soil surface on each plot. The method was simple to apply and consists of following steps: (i) Wet the soil from a rainfall simulator with several known discharge rates on a relatively leveled soil surface with and without organic matter. (ii) Once the borders of the ponded zone were steady, saturated hydraulic conductivity( $K_{s}$) and the matric flux function(F) was evaluated from a regression of flux vs. the reciprocal of the ponded area. A conductivity of the form $K_{i+}$$_1$ $_{c}$= $K_{i}$( $_{c}$) [1-d /dz] where flux continuity implies. For this, continuity of matric potential at the interface at all times are as follows: $_1$( $Z_{c}$) = $_2$( $Z_{c}$) = $_{c}$ for steady state intake from water ponded on the soil surface. Results of this investigation showed the importance of understanding spatial variability in wide differences of water retention and saturated hydraulic conductivity with respect to pore geometry and organic matter contents which influenced the water flux throughout the soil profile.l profile.ile.

• Journal of Integrative Natural Science
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• v.7 no.3
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• pp.149-158
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• 2014

The crystal structure of the title compounds with both coumarin and sulfonamide moieties were examined. These two groups have very special for their pharmaceutical and medicinal properties have been determined from single crystal X-ray diffraction data. In the title compound crystallizes in the monoclinic space group $P2_1/c$ with unit cell dimension a=$8.5775(4){{\AA}$, b=$24.9943(13){\AA}$ and c=$13.7319(7){\AA}$ [alpha & gamma=$90^{\circ}$ beta=$103.558(2)^{\circ}$]. In the structure The S1 atom shows a distorted tetrahedral geometry, with O1-S1-O2 [$121.08(1)^{\circ}$] and N1-S1-C5 [$105.85(1)^{\circ}$] angles deviating from ideal tetrahedral values are attributed to the Thrope-Ingold effect. The sum of bond angles around N1 ($354.9^{\circ}$) indicates that N1 is in $sp^2$ hybridization. The Pyridine ring adopts boat conformation and pyran rings adopt a sofa conformation. Crystal structure is stabilized by C-H...O intra molecular hydrogen bond interactions.