• Korean Journal of Materials Research
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• v.13 no.10
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• pp.677-682
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• 2003

SiC nanowires were synthesized by carbothermal reduction using metal catalysts. Synthesized nanowires had mean diameters of 30∼50 nm and several $\mu\textrm{m}$ length. The kind of catalysts affects form of SiC nanowire because of difference of growth mechanisms. These differences were made by catalyst's physical property and relative activities to the source gas. Ni acted a conventional catalyst of VLS growth mechanism. But, Case of Fe, SiC nanowire was grown by stable VLS growth mechanism without relation of growth conditions. SiC nanowire was grown by two step growth model using Cr catalyst. Conversion ratios to the SiC nanowire were increased with growth conditions. Case of Cr, conversion ratio was about 45% that was higher than other catalyst used. This high conversion ratio was obtained by the addition VS growth to radial direction on the as-grown nanowires.

• Bulletin of the Korean Chemical Society
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• v.14 no.5
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• pp.567-574
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• 1993

Mordant Red 19(MR19) is reduced at mercury electrode at -0.67 V vs. Ag/AgCl with two electrons per molecule in pH 9.2 buffer by differential pulse polarography and linear sweep voltammetry. The peak potential is dependent on the pH of solution. The exhaustive electrolysis, however, gives 4 electrons per molecule because of the disproportionation of the unstable hydrazo intermediate. The electrochemical reduction of lanthanide-MR19 complexes is observed at more cathodic potential than that of free ligand. The difference in peak potentials between complex and free ligand varies from 75 mV for $La^{3+}$ to 165 mV for $Tb^{3+}$ and increases with increasing the atomic number of lanthanide. The electrochemical reduction of lanthanide complexes with MR19 is due to the reduction of ligand itself, and it can be potentially useful as an indirect method for the determination of lanthanides. The shape of i-E curves and the scan rate dependence indicates the presence of adsorption and the adsorption was confirmed by potential double-step chronocoulometry and the effect of standing time. Also the surface excess of the adsorbed species and diffusion coefficients are determined. The composition of the complex is determined to be 1 : 2 by spectrophotometric and electrochemical methods.

• Journal of the Korean institute of surface engineering
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• v.55 no.2
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• pp.63-69
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• 2022

Preparing various types of thin films of oxide semiconductors is a promising approach to fabricate efficient photoanodes and photocathodes for hydrogen production via photoelectrochemical (PEC) water splitting. In this work, we investigate the feasibility of an efficient photocathode for PEC water reduction of a p-type oxide semiconductor cupric oxide (CuO) thin film prepared via a facile method combined with sputtering Cu metallic film on fluorine-doped thin oxide (FTO) coated glass substrate and subsequent thermal oxidation of the sputtered Cu metallic film in dry air. Characterization of the structural, optical, and PEC properties of the CuO thin film prepared at various Cu sputtering powers reveals that we can obtain an optimum CuO thin film as an efficient PEC photocathode at a Cu sputtering power of 60 W. The photocurrent density and the optimal photocurrent conversion efficiency for the optimum CuO thin film photocathode are found to be -0.3 mA/cm² and 0.09% at 0.35 V vs. RHE, respectively. These results provide a promising route to fabricating earth-abundant copper-oxide-based photoelectrode for sunlight-driven hydrogen generation using a facile method.

• Journal of The Korean Digital Architecture Interior Association
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• v.12 no.1
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• pp.89-98
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• 2012

While the housing transaction price of Seoul tends to be stagnant or declining in line with the housing market recession since 2007, the jeonse price keeps continual increase. Such flow of jeonse price change has a serious influence on ordinary person's housing stability seriously. Therefore, it is very meaningful in terms of social policy to analyze the trend of recent jeonse price change. This study aims to have an empirical analysis of structural characteristics of the trend of recent jeonse price change. After the review of various previous studies, this study selected housing jeonse price index, non-sold house quantity, jeonse vs. transaction price rate, and housing construction performance as analytical variables, and employed monthly time series resources from January 2007 to April 2011. As a result, when the housing supply reduced, the potential quantity for jeonse market reduced that occurred unbalance of supply and demand in jeonse market. In turn, it caused the increase of jeonse price. And, in case of jeonse vs. transaction price rate change, the rate increased which means the increase of required rate of return of invested demand. As such, the increase of market risk degenerates the investment sentiment which caused the reduction of quantity for jeonse market as a submarket.

• Korean Journal of Biological Psychiatry
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• v.3 no.2
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• pp.258-261
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• 1996

Objective : Several studies hove suggested that reduction of cholesterol concentration and low cholesterol level increases suicide, homicide, and depression. The authors sought to determine whether low cholesterol is associated with a history of suicidal attempts among major depression patients. Method : The subjects were 105 patients with major depression, diagnosed according to the DSM-III-R criteria, and 105 age, sex matched healthy controls. Blood was token following overnight fast and serum cholesterol concentration were measured by a enzymatic method Results : The serum cholesterol level was significantly lower in the patients with major depression than in healthy controls($180.4{\pm}43.4mg/dl$ vs $199.7{\pm}35.8mg/dl$). And the serum cholesterol level was significantly lower in major depression patients with suicidal attempt than in major depression patients without suicidal attempt($156.7{\pm}38.2mg/dl$ vs $ 187.8{\pm}42.5mg/dl$) Conclusion : It is hypothesized that low cholesterol level is associated with depression by modifying the serotonin metabolism and the production of interleukin-2, low cholesterol concentration should be further investigated as a potential biological marker of suicidal risk in major depression. Prospective study with serial cholesterol determinations should be done.

• Korean Management Science Review
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• v.27 no.2
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• pp.1-20
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• 2010

Many firms are trying to acquire innovative technologies and relative knowledge by offshoring R&D work. Although research to date has focused on the multinational corporations' motivations of R&D offshoring, such as cost reduction and market expansion, little is known about external or environmental factors influencing the performance of global R&D activities. We investigated the relationship between the offshore R&D performance and the technical capabilities of the parent company, the host country and the home country as enhancers from outside R&D facilities. The analysis uses European patent data and EU R&D scoreboard of 134 overseas R&D labs from 46 multinational corporations in 2005. Also, we calculated total patent number of each country for this. Results from path analysis supported our main hypothesis that the technological capabilities of the parent company and the host country positively affect the overseas R&D performances. By multi-group analysis, we also found that the relationships among the variables are different for each industry.

• International journal of advanced smart convergence
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• v.9 no.3
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• pp.221-226
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• 2020

Smart homes have become the state of the art in the reduction and monitoring of energy usage within a residential setting. Emerging threats such as climate change, global warming and volatility in energy prices have fuelled the interest in smart systems. Given that environmental sustainability has become a more significant factor for consumers, this research examines whether consumers' attitudes toward smart home services for efficient energy management differ according to their regulatory focus. Specifically, it is predicted that consumers will have more favorable attitudes toward smart home services for efficient energy management when they are promotion-focused (vs. prevention-focused). The results indicate that respondents with a promotion (vs. prevention) focus reported significantly more favorable attitudes toward smart home services for energy management (e.g., smart cooling/heating system, smart ventilation & air conditioning system, smart thermostats, smart plugs, and smart switches). We suggest that regulatory focus may be an effective marketing and segmentation tool in promoting smart home services for energy management and facilitating their receptiveness to the services.

• Clinical and Experimental Reproductive Medicine
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• v.47 no.3
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• pp.186-193
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• 2020

Objective: The effectiveness of Staphylococcus protein A (SPA) in improving the penetration ability of sperm and reducing antisperm antibody (ASA) titers in immunologically infertile males was evaluated. Methods: Seminal fluid samples were obtained from 15 infertile men, and ASA titers were assessed with the latex agglutination test. Identification of immunoglobulin (Ig) classes and characterization of the antigens involved in the immune response were performed using indirect immunofluorescence. Local ASAs typically present as a mixture of IgG and IgA classes. The capillary tube penetration method was used to assess the capability of spermatozoa to penetrate the cervical mucus (CM). Results: ASAs associated with the neck region of sperm showed a significantly lower migration distance in the CM of infertile females than ASAs associated with the head or tail segments. ASA-positive seminal fluid exhibited significant increases in the mean migration distance (2.6 ± 1.4 cm vs. 1.54 ± 1.1 cm, respectively; p< 0.001) and sperm concentration (174 ± 121.0 × 10³/mL vs. 101 ± 93.7 × 10³/mL, respectively; p= 0.033) after treatment with SPA compared to pre-treated samples. A significant reduction (p< 0.01) in the recorded ASA titer was detected. Conclusion: These results indicate that SPA can be used as a sorting regimen for insemination programs. However, further studies are warranted to assess its influence on pregnancy rate.

• Transactions of Materials Processing
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• v.24 no.6
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• pp.411-417
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• 2015

The piston engine is an essential component in automobiles. Since the piston is used in a high temperature and high pressure environment, the piston needs to be manufactured to achieve high strength and high durability. In addition, cost reduction is also an important consideration. In conventional forging, an additional heat treatment after hot forging is necessary to ensure proper mechanical properties for heavy-duty engine pistons. The newly developed manufacturing method lowers production costs by saving manufacturing time and reduces energy consumption. The current paper describes the hot forging of an engine piston made from 38MnSiVS5 micro-alloyed steel using controlled cooling. The finite element analysis was used to check for possible problems and suitable press capacity. Hot forging experiments were then conducted on a 2500tons crank press to evaluate feasibility of the proposed material and process. To check the mechanical properties after hot forging, the forged specimens were tensile tested, and the microstructures were examined in order to compare the results with the conventionally forged material. The skirt region of the as-forged 38MnSiVS5 piston showed better material properties compared to the conventional material. In addition, the total production time was reduced by about 80% as compared to conventional forging.

• Journal of Sensor Science and Technology
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• v.16 no.6
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• pp.407-412
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• 2007

For $VO_{2}$ sensors applicable to temperature measurement by using the nature of semiconductor to metal transition, the crystallinity, microstructure, and temperature vs. resistance characteristics were investigated systematically as a function of the annealing condition. The starting materials, vanadium pentoxide ($V_{2}O_{5}$) powders, were mixed with vehicle to form paste. This paste was screen-printed on $Al_{2}O_{3}$ substrates and then $VO_{2}$ thick films were heat-treated at $450^{\circ}C$ to $600^{\circ}C$, respectively, for 1 hr in $N_{2}$ gas atmosphere for the reduction. As results of the temperature vs. resistance property measurements, the electrical resistance of the $V_{2}O_{5}$ sensor in phase transition range was decreased by $10^{3.9}$ order. The presented critical temperature sensor could be used in fire-protection and control systems.