• IMMUNE NETWORK
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• v.7 no.3
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• pp.133-140
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• 2007

Background: It is well established that cross talk between natural killer (NK) cells and myeloid dendritic cells (DC) leads to NK cell activation and DC maturation. In the present study, we investigated whether type 1-polarized DC (DC1) matured in the presence of IFN-${\gamma}$ and type 2-polarized DC (DC2) matured in the presence of PGE2 can differentially activate NK cells. Methods: In order to generate DC, plastic adherent monocytes were cultured in RPMI 1640 containing GM-CSF and IL-4. At day 6, maturation was induced by culturing the cells for 2 days with cytokines or PGE2 in the presence or absence of LPS. Each population of DC was cocultured with NK cells for 24 h. The antigen expression on DC was analyzed by flow cytometry and cytokine production in culture supernatant was measured by ELISA or a bioassay for TNF-${\alpha}$ determination. NK cell-mediated lysis was determined using a standard 4h chromium release assay. Results: DC2, unlike DC1, had weak, if any, ability to induce NK cell activation as measured by IFN-${\gamma}$ production and cytolytic activity. DC2 were weakly stimulated by activated NK cells compared to DC1. In addition, IFN-${\gamma}$-primed mature DC appeared to be most resistant to active NK cell-mediated lysis even at a high NK cell/DC ratio. On the other hand, PGE2-primed DC were less resistant to feedback regulation by NK cells than IFN-${\gamma}$-primed mature DC. Finally, we showed that the differential effect of two types of DC population on NK cell activity is not due to differences in their ability to form conjugates with NK cells. Conclusion: These results suggest that different combinations of inflammatory mediators differentially affect the effector function of DC and, as a result, the function of NK cells, eventually leading to distinct levels of activation in adaptive immunity.

• Journal of Pharmaceutical Investigation
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• v.29 no.3
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• pp.227-234
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• 1999

Solid dispersions were prepared to increase the dissolution rate of biphenyl dimethyl dicarboxylate (DDB) using water-soluble carriers such as povidone, copolyvidone, $2-hydroxypropyl-{\beta}-cyclodextrin (HPCD)$, sodium salicylate or sodium benzoate by solvent evaporation method. Solid dispersions were characterized by infrared spectrometry, differential scanning calorimetry (DSC) and powder X-ray diffractometry, dissolution and permeation studies. DDB tablets (7.5 mg) were prepared by compressing the powder mixtures composed of solid dispersions, lactose, com starch, crospovidone and magnesium stearate using a single-punch press. DDB capsules (7.5 mg) were also prepared by filling the mixtures in empty hard gelatin capsules (size No.1). From the DSC and powder x-ray diffractometric studies, it was found that DDB was amorphous in the HPCD or copolyvidone solid dispersions. Dissolution rates after 10 min of DDB alone and solid dispersions (1 : 10) in sodium benzoate, sodium salicylate and copolyvidone were 11.8, 23.5, 22.8 and 82.5%, respectively. Dissolution rates of DDB after 30 min from 1 : 10 and 1 : 20 copolyvidone solid dispersions were 80.5 and 95.0%, respectively. For the DDB tablets prepared using solid dispersions (1 : 20), the initial dissolution rate was dependent on carrier material, and was ranked in order, $Kollidon\;30\;{\ll}$ copolyvidone < HPCD. For the HPCD solid dispersion tablets, dissolution rate reached 97.4% after 15 min, but thereafter slowly decreased to 80.7% after 2 hr due to the precipitation of DDB. However, in the case of copolyvidone solid dispersion tablets, dissolution increased linearly and reached 93.4% after 2 hr. Reducing the volume of test medium from 900 to 300 ml markedly decreased the dissolution rate of the tablets containing 1 : 20 HPCD solid dispersions and 1 : 10 copolyvidone solid dispersion. For 1 : 20 copolyvidone solid dispersion tablets, there was no significant change in dissolution rate up to 1 hr with different volumes of test medium. Preparation of the copolyvidone solid dispersion (1 : 20) in capsules markedly delayed the dissolution (31.2 % after 2hr) due to the limited diffusion within capsules. The permeation rate $(13.4\;g/cm^2\;after\;8\;hr)$ of DDB through rabbit duodenal mucosa from copolyvidone solid dispersion (1 : 10) was markedly enhanced, when compared with drug alone or physical mixtures. From overall findings, DDB formulations containing copolyvidone solid dispersions (1 : 20) could be used to remarkably improve the dissolution rate in dosage form of powders and tablets.

• Archives of design research
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• v.17 no.1
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• pp.329-338
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• 2004

This study did derive a characteristic of a cover design through considering a concept, a function and components of a cover design based on a literature study and through analyzing cases of the best-seller cover designs for the literature section from 1999 to 2002. In terms of a reader's preference for a cover design according to an age and sex of a reader, it tried to suggest a condition and a method of a book-cover design through a questionnaire survey and the image evaluation. In a survey of the preference for a cover design, there was the difference of interest degree in a kind of a book, a place to buy a book and a cover design according to an age and sex. In addition, it was shown that a woman prefers the stylish typography, and both a man and a woman prefer the cool color. However, except these two, the reason why there is no difference in preference for visual elements are that a cover design is an integrative image comprising several elements. Accordingly, through the Semantic Differential Method, it carried out the evaluation as to a cover design as an integrative image. As a result of that, an abstract image was shown to be difficult to convey a meaning because of its fall in clarity. Further, a cover design mainly comprising the stylish typography gained the high evaluation in unique and clarity. It is thought to be attributable to the easiness to achieve a goal of seeing and reading in a cover design in which an image and the typography are balanced, rather than the excessive visual. Even though the visual is excellent, there was difference from what having been excellent in conveying a meaning, which is a functional aspect. This study tried to examine, limiting it only to a visual element. It will be hereafter required to proceed with a study on the influence on a reader's preference according to material, bookbinding and a form of book which are elements comprising a cover design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.27-33
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• 2016

Phenolic resin has excellent heat resistance and good mechanical properties as a thermosetting resin. However, its thermosetting characteristics cause it to produce a non-recyclable waste in the form of sprue and runner which is discarded and represents up to 15~20% of the overall products. Forty thousand tons of phenolic resin sprue and runner are disposed of (annually). The (annual) cost of such domestic waste disposal is calculated to be 20 billion won. In this study, discarded phenol resin scraps were pulverized and treated by silanes to improve their interfacial adhesion with HDPE. The sizes of the pulverized pulverulent bodies and fine particles were (100um~1000um) and (1~100um), respectively. The pulverized phenol resin was treated with 3-(methacryloyloxy) propyltrimethoxysilane and vinyltrimethoxy silane and the changes in its characteristics were evaluated. The thermal properties were evaluated by DSC and HDT. The mechanical properties were assessed by a notched Izod impact strength tester. When the silane treated phenol resin was added, the heat distortion temperature of HDPE increased from $77^{\circ}C$ to $96^{\circ}C$ and its crystallinity and crystallization temperature also increased. Finally, its impact strength and tensile strength increased by 20% and 50%, respectively, in comparison with the non-treated phenol resin.

• Journal of The Geomorphological Association of Korea
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• v.19 no.3
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• pp.51-69
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• 2012

Physical strength of the rock is the most important factor of resistance to erosion and has been measured through various way. Bedrock microforms, like potholes and grooves, are the forms sculpted by the erosional processes of flow and the location and morphology are strongly affected by the differential erosion. It also assumed that the physical strength of the rock controls the erosion rate and mode of erosion. The schmidt hammer has been used to measure the rock strength in the field for the geomorphological research. To find the relationship between the rock strength and microforms, Schmidt hammer's R(rebound) were measured in the Baeksuktan, middle reach of Gilancheon, Cheongsong, Gyungsangbuk do. The overall values of rebound of the local sandstone showed over 65 in most cases, so it can be regarded as 'very strong'. It is found that the rebound values of the rock surface decreased towards current water level. It also, however, found that there was no systematic differences in rebound values among the topographically high and lows in the bedrock surface. There was no statistically significant difference in rebound values of the area with well developed microforms and others. The values of R from the exposed faces and inside of the microforms are similar. In the case of conglomerate, the part with the gravel showed higher values that the parts with sands. The rebound values are decreased near of(<1cm) the geological discontinuities(including joint and faults), so this line of weakness could be the point of initiation of active erosion to form microforms. However there is large variations in rebound values within this part. It also should be mentioned that topological relation between the strike of the geologic discontinuities and flow direction looks control the mode of erosional processes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.86-92
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• 2019

Polymers with various compositions of azobenzene and hexamethylene groups in the main chain were synthesized by a Schotten-Baumann reaction and their properties were investigated. The chemical structures and physical properties of the synthesized polymers were investigated by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, differential scanning calorimetry, thermogravimetric analysis, polarized optical microscopy, and x-ray diffraction. The polymers showed an inherent viscosity of 1.28-1.36 dl/g and were relatively insoluble in most organic solvents. The melt transition temperature increased rapidly with increasing number of azobenzene groups in the polymer. When the azobenzene monomer content was more than 50 mol%, no melting transition occurred below the decomposition temperature. Among the polymers with a melt transition temperature, the MP-A3C7 and MP-A5C5 polymers were liquid crystalline materials and exhibited a nematic phase with weak liquid crystallinity over a wide liquid crystal temperature range. This difference in the properties of the synthesized polymers is likely due to the changes in intermolecular forces resulting from the linearity and polarity of the trans-form of azobenzene.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.461-466
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• 2021

In this article, a portable and cost-effective voltammetric biosensor with nanoparticles was developed for the measurements of heterogeneous nuclear ribonucleoprotein A1 protein (hnRNP A1) biomarker which can potentially be used for lung cancer diagnosis. Gold nanoparticles were first electrodeposited onto screen printed carbon electrode (SPCE) followed by immobilizing a single stranded DNA aptamer specific to hnRNP A1 onto the electrode surface. Ethanolamine was also used when immobilizing DNA aptamer on the surface to prevent signals from non-specific adsorption events. Sequential injection of hnRNP A1 biomarker and anti-hnRNP A1 conjugated with alkaline phosphatase (ALP) onto the aptamer chip surface allows to form the sandwich complex of DNA aptamer/hnRNP A1/ALP-anti-hnRNP A1 on the electrode surface which further reacted with 4-aminophenyl phosphate (APP). The electrocatalytic reaction of the enzyme, ALP, and the substrate, APP, resulting in the oxidative current response changes at -0.05 and -0.17 V (vs. Ag/AgCl) against the hnRNP A1 concentration was measured using cyclic and differential pulse voltammetry, respectively. The Au nanoparticles-integrated voltammetric biosensor was applied to analyze human normal serum solutions possibly suggesting potential applicability for lung cancer diagnosis.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.71-79
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• 2021

In this study, we have successfully fabricated the Sn-Ni paste and evaluated the bonding properties for high-temperature endurable EV (Electric Vehicle) power module applications. From evaluating of the micro-structural changes in the TLPS (Transient Liquid Phase Sintering) joints with Sn and Ni contents in the Sn-Ni pastes, a lack of Ni powders and Ni particle agglomerations by Ni surplus were observed in the Sn-20Ni and Sn-50Ni joints (in wt.%), respectively. In contrast, relatively dense microstructures are observed in the Sn-30Ni and Sn-40Ni TLPS joints. From differential scanning calorimetry (DSC) thermal analysis results of the fabricated Sn-Ni paste and TLPS bonded joints, we confirmed that the complete reactions of Sn with Ni to form Ni-Sn intermetallic compounds (IMCs) at bonding temperatures occurred, and there is no remaining Sn in the joints after TLPS bonding. In addition, the interfacial reactions and IMC phase changes of the Sn-30Ni joints under various bonding temperatures were reported, and their mechanical shear strength were investigated. The TLPS bonded joints were mainly composed of residual Ni particles and Ni₃Sn₄ intermetallic phase. The average shear strength tended to increase with increasing bonding temperature. Our results indicated a high shear strength value of approximately 30 MPa at a bonding temperature of 270 ℃ and a bonding time of 30 min.

• The Journal of the Korea Contents Association
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• v.22 no.1
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• pp.99-115
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• 2022

In this study, domestic academic journal papers on tax compliance, tax consciousness, and faithful tax payment (hereinafter referred to as "tax compliance") were comprehensively analyzed from an interdisciplinary perspective as a representative research topic in the field of tax science. To achieve the research purpose, topic modeling technique was applied as part of text mining. In the flow of data collection-keyword preprocessing-topic model analysis, potential research topics were presented from tax compliance related keywords registered by the researcher in a total of 347 papers. The results of this study can be summarized as follows. First, in the keyword analysis, keywords such as tax investigation, tax avoidance, and honest tax reporting system were included in the top 5 keywords based on simple term-frequency, and in the TF-IDF value considering the relative importance of keywords, they were also included in the top 5 keywords. On the other hand, the keyword, tax evasion, was included in the top keyword based on the TF-IDF value, whereas it was not highlighted in the simple term-frequency. Second, eight potential research topics were derived through topic modeling. The topics covered are (1) tax fairness and suppression of tax offenses, (2) the ideology of the tax law and the validity of tax policies, (3) the principle of substance over form and guarantee of tax receivables (4) tax compliance costs and tax administration services, (5) the tax returns self- assessment system and tax experts, (6) tax climate and strategic tax behavior, (7) multifaceted tax behavior and differential compliance intentions, (8) tax information system and tax resource management. The research comprehensively looked at the various perspectives on the tax compliance from an interdisciplinary perspective, thereby comprehensively grasping past research trends on tax compliance and suggesting the direction of future research.

• Journal of Digital Convergence
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• v.20 no.5
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• pp.393-400
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• 2022

In a situation where the company handles accounting conservatively, the management's earnings forecasting information will be more conservative, and the conservativeness of this earnings forecasting information will have a differential effect in evaluating the performance of managers and paying compensation. This study aims to examine how the level of corporate accounting conservatism affects the forecast information of managers and how this affects the compensation of managers. This study establishes a hypothesis on the effect of the level of accounting conservatism on the earnings forecasting information and compensation of managers, and examines the relationship between managerial profit forecasting information & manager compensation according of conservatism in corporate accounting that can vary depending on the manager's disposition. As a result of the analysis, conservative managers are also conservative in earnings forecasting disclosure, and when corporate managers are highly conservative, they show their ability by making earnings forecasts disclosures more frequently and more accurately than corporate managers with low conservatism. It will help reduce the forecasting errors of stakeholders. Therefore, it is expected that this will play an important role in judging the manager's ability and determining compensation. Therefore, when a company handles accounting conservatively, management's earnings forecasts are also measured conservatively, which is expected to provide useful information on the basis and form of management's compensation to stakeholders.