• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.66-82
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• 2017

Organosilicone-based surfactants consist of hydrophobic organosilicone groups coupled to hydrophilic polar groups. Organosilicone surfactants have been widely used in many industrial fields starting from polyurethane foam to construction materials, cosmetics, paints & inks, agrochemicals, etc., because of their low surface tension, lubricity, spreading, water repellency and thermal and chemical stability, resulted from the unique properties of organosilicone. Especially, trisiloxane surfactants, having low molecular weight organosilicone as hydrophobe, exhibit low surface tension and excellent wettability and spreadability, leading to their applications as super wetter/super spreader, but have the disadvantage of vulnerability to hydrolysis. A variety of trisiloxane surfactant structures are required to provide the functional improvement and the defect resolution for reflecting the necessities in the various applications. This review covers the synthetic schemes of reactive trisiloxanes as hydrophobic siloxane backbones, the main reaction schemes, such as hydrosilylation reaction, for coupling reactive trisiloxanes to hydrophilic groups, and the synthetic schemes of the main trisiloxane surfactants including polyether-, carbohydrate-, gemini-, bolaform-, double trisiloxane-type surfactants.

• Journal of the Korean Applied Science and Technology
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• v.34 no.3
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• pp.461-477
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• 2017

Organosilicone-based surfactants, consisting of hydrophobic organosilicone groups coupled to hydrophilic polar groups, have been widely used in many industrial fields starting from polyurethane foam to construction materials, cosmetics, paints & inks, agrochemicals, etc., because of their low surface tension, lubricity, spreading, water repellency and thermal and chemical stability, resulted from the unique properties of organosilicone. Especially, organosiloxane surfactants, having low molecular weight siloxane as hydrophobe, exhibit low surface tension and excellent wettability and spreadability, leading to their applications as super wetter/super spreader, but have the disadvantage of vulnerability to hydrolysis. A variety of low molecular weight siloxane surfactant structures are required to provide the functional improvement and the defect resolution for reflecting the necessities in the various applications. This review includes the synthetic schemes of reactive tetrasiloxanes and disiloxanes as hydrophobic siloxane backbones, the main reaction schemes, such as hydrosilylation reaction, for coupling reactive tetrasiloxanes or disiloxanes to hydrophilic groups, and the main synthetic schemes of the tetra- and di-siloxane surfactants having polyether-, carbohydrate-, gemini-, bola-type surfactant structures.

• Polymer(Korea)
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• v.29 no.5
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• pp.468-474
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• 2005

PLGA and PCL copolymers initiated by carbitol as drug carriers were synthesized by ring-opening polymerization of L-lactide (LA), glycolide (GA), and $\varepsilon-caprolactone(\varepsilon-CL)$. Implantable wafers were simply fabricated by direct compression method after physical mixing of copolymers and bovine serum albumin-fluorescein isothiocyanate (BSA-FITC) as a model protein drug. The release amounts of BSA-FITC from wafers were determined by fluorescence intensity using the fluorescence spectrophotometer. Also, the release behavior of BSA-FITC on wafers was controlled by adding the additives such as collagen, small intestinal submucosa (SIS), poly(vinyl pyrrolidone) (PVP), and poly(thylene glycol) (PEG). The wafer prepared by PLGA and PCL exhibited slow release within $10\%$ for 30 days. But, those prepared by a variety of additives exhibited the controlled BSA release patterns with a dependence on the additive contents. furthermore, the wafers containing natural materials such as collagen and SIS showed more zero-order release profile than that with synthetic materials such as PVP and PEG. It was confirmed that the release of BSA from implantable wafers could be easily controlled by adding natural additives.

• Economic and Environmental Geology
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• v.53 no.6
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• pp.703-713
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• 2020

In many geological fields, including hydrogeology, it is of great importance to determine the heterogeneity of the subsurface media. This study briefly introduces the concept and theory of the method that can estimate the hydraulic properties of the media constituting the aquifer, which was recently introduced by Park (2020). After the introduction, the method was applied to the synthetic aquifer to demonstrate the practicality, from which various implications were drawn. The introduced technique uses a global optimization technique called the covariance matrix adaptation evolution strategy (CMA-ES). Conceptually, it is a methodology to characterize the aquifer heterogeneity by assimilating the groundwater level time-series data due to the imposed hydraulic stress. As a result of applying the developed technique to estimate the hydraulic conductivity of a hypothetical aquifer, it was confirmed that a total of 40000 unknown values were estimated in an affordable computational time. In addition, the results of the estimates showed a close numerical and structural similarity to the reference hydraulic conductivity field, confirming that the quality of the estimation by the proposed method is high. In this study, the developed method was applied to a limited case, but it is expected that it can be applied to a wider variety of cases through additional development of the method. The development technique has the potential to be applied not only to the field of hydrogeology, but also to various fields of geology and geophysics. Further development of the method is currently underway.

• Korean Journal of Agricultural Science
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• v.29 no.1
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• pp.32-43
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• 2002

The peach pyralid moth (Dichocrocis punctiferalis) is reported as import ant pest insect to chestnut fruits in Asia including Korea. For seasonal occurrence of D. punctiferalis in 1996, 1998 and 1999, D. punctiferalis adults were collected by light trap and sex pheromone wing trap in the chestnut orchard. Also, damaged rate of chestnut fruits were examined each collecting site. In 1996, according to examination by using light trap at three different site in Kongju, the occurrence peak of 2nd gene ration of D. punctiferalis adults was early August. Collected individuals after September were cons ide red as 3rd generation. Damaged rate due to maturation type was 26.5% averagely. The order of damaged rate were early, late and middle maturation type as 35.04%, 19.35% and 26.03%, respectively. Using synthetic sex pheromone trap at Kongju, Cheungyang and Buyeo in 1998, occurrence peaks were occurred mid-August to 2nd generation and late September to 3nd gene ration in Kongju. However, from early-August to late-September 5 peaks were occurred sequentially in Cheungyang. Second generation adults were occurred in mid-August and 3rd ones were occurred from late-September to early-October in Buyeo. In 1999, occurrence peaks of 3rd generation were early, middle and late September in Kongju, Cheungyang and Buyeo respectively. Damaged rate were 6.8%, 6.6% and 15.3% in Kongju, Cheungyang and Buyeo, respectively. Damaged rate order due to variety were Eunki, Chukpa, Danpa, Bokpa, Wangjung, Byunggo57, Yuoma at Buyeo and were Chukpa, Dukmyung, Byunggo57 at Cheungyang in 1999. Damage rate of chestnut were different with variety. Eunki and Chukpa in Buyeo and Chukpa and Dukmyung in Cheungyang were more damaged by D. punctiferalis respectively.

• Geophysics and Geophysical Exploration
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• v.15 no.2
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• pp.51-56
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• 2012

One of the most critical and essential procedures in the interpretation of gravity and magnetic data is to separate the anomaly due to the specific geologic structure from the summation of effects from a broad variety of geologic sources, especially those of different depths. Separation of the residual anomaly from the regional field is the most simple case of the vertical separation. If the anomaly due to a layer of specific depth can be separated or the depth of the separated layer can be quantitatively determined, it may deserve the separation-sounding. We suggest a wavelength filter whose cutoff frequency is determined by log-power spectrum analysis, as a separation-sounding filter. We applied this filter both to synthetic and real gravity data acquired at Heunghae area, and compared the results with those of Jacobsen's upward continuation filter. These showed that the proposed separation-sounding filter could be a useful tool for interpretation of the vertical geologic structure by stripping the gravity effects of geologic sources down to the desired depth.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.212-221
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• 1999

The periapical response to injury is a complex interaction of inflammatory, immune, neural, vascular and synthetic activity. Nitric oxide(NO), synthesized by nitric oxide synthetase(NOS) from L-arginine, is becoming recognized as an important bio-regulatory molecule in a variety of tissue, but little is known about its possible role in periapical tissue. The purpose of this study was to investigate the expression of nitric oxide synthetase(NOS) in tooth follicle, periapical abscess, granuloma and cyst. The expression of NOS in periapical lesions was evaluated by immunohistochemical staining for $NOS_2$, and $NOS_3$. The immunoreactivity was evaluated by staining intensity, and inflammatory cell infiltration. Correlationship between the periapical lesion in immunoreractivity were statistically analyzed by SPSS. The degree of $NOS_2$ and $NOS_3$ expression in periapical abscess was higher than in any other periapical lesions, and stastically significant. The expression degree of $NOS_2$ and $NOS_3$ was not correlated with periapical abscess and granuloma, but expression of $NOS_2$ showed very significant in periapical cyst. The increased expression of $NOS_2$ and $NOS_3$ was correlated with inflammatory cell infiltration degree of the periapical cyst. These results suggested that NO should play an important role in progress and/or mediation of periapical lesions.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.05a
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• pp.181-182
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• 2003

Exposure to some synthetic environmental chemicals and their metabolites cause reproductive problems in a variety of vertebrate via endocrine mechanisms. However, in most cases, the link between these compounds and adverse effects on humans, fish, and wildlife has not been established, which necessitates a closer look at the molecular, functional, and clinical implications of these chemicals in the environment. Calbindin-D9k (CaBP-9k) is a member of a largo family of intracellular calcium binding proteins that have high affinities for calcium. It was reported that the estrogen level of uterus affected the expression of the CaBP-9k gene in rat uterus. We examined the dose-dependent CaBP-9K gene expression in the uterus for three-days injection of methoxychlor (HC) in the overectomized immature rats and the relation with uterotrophic response of the compoundsand compared the responses induced by MC according to the route of administration.

• Journal of Microbiology and Biotechnology
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• v.10 no.1
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• pp.1-7
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• 2000

Bioconversion of fumarate to succinate was anaerobically conduced in a synthetic medium containing glycerol as a hydrogen donor and fumarate as a hydrogen acceptor. We investigated the effects of pH, carbon and nitrogen sources, conversion substrate, and other culture conditions on the production of succinate using a nwely isoloated Enterococcus facalis PKY1. Addition of a variety of carbonates to the medium significantly increasd the rates of production of succinate. The production of succinate and cell growth were relatively satisfactory in the pH range of 7.0-7.6. By using glycerol as a hydrogen donor, high purity succinate was produced with few byproducts. Yeast extract as a sole nitrogen source was the most effective for producing succinalte. As a result, the optimum condition of biconversion was obtained at a medium containing 20g/I glycerol, 50 g/l fumarate, 15 g/l yeast extract, 10 g/l $K_2HPO_4$, 1 g/I NaCl, 50ppm $MgCl_2{\cdot}6H_2O$, 10ppm $FeSo_4{\cdot}7H_2O$, and 5 g/I $Na_2CO_3$ at pH 7.0-7.6. Under the optimum condition, a succinate concentration of 153 g/I was produced in 36 h. The total volumetric production rate and the molar yield of succinate were 4.3 g/l/h and 85%, respectively.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.28 no.3
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• pp.7-39
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• 2002

The extensive variation in human cutaneous pigmentation is mainly due to differences in the rate of melanin synthesis by epidermal melanocytes, the relative amounts of eumelanin and pheomelanin synthesized, and the manner and rate of transfer of melanosomes from melanocytes to keratinocytes. Pigmentation is a complex trait that is regulated genetically and environmentally. One gene that has been receiving a lot of attention is the gene for the melanocortin 1 receptor The extensive polymorphism of this gene in human populations suggests its significance in the diversity of pigmentation. Exposure to solar ultraviolet radiation (UV) results in increased synthesis of a variety of growth factors, cytokines and hormones, and in modulation of their receptors in the epidermis. Knowledge about the regulation of pigmentation has led to strategies for clinical treatment of hyperpigmented skin lesions. Three main strategies are: 1) the use of chemicals that interfere with the melanin synthetic pathway, 2) the design of peptides or peptide-mimetics based on the structure of hormones that regulate eumelanin synthesis, and 3) the use of agents that reduce melanosome transfer from melanocytes to keratinocytes. All three strategies are expected to induce hypopigmentation, by inhibiting total melanin synthesis, eumelanin production, or the epidermal melanin unit, respectively.