• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.2
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• pp.81-87
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• 2017

The pipe connection process using a clamping ring is used for joining small pipes in the refrigerator and air-conditioner industries instead of the brazing process, which induces inevitable thermal deformation in the pipes. However, few studies have been carried out on the process to select optimal parameters in joining pipes, and studies on the relation between the process parameters of the connection and connecting force of the joint have not been conducted. In this study, the connection process of pipes with the clamping ring was modeled using the finite element method (FEM) and analyzed to obtain the contact stress distribution between the pipes with which the connecting force of the joint was estimated. Considering the characteristics of pipe connection, the process was modeled and simulated in a two-dimensional axisymmetric solution domain. With the numerical model, the effect of ring shape on the connection was studied by adding a projection to the end of a ring or changing the length of a ring. The results of the analyses revealed that the contact stress distribution could be predicted with the suggested model. The effect of the ring shape was also presented. The effect of any combination of process parameters could be easily estimated through the related analyses.

• Korean Journal of Pharmacognosy
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• v.32 no.4 s.127
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• pp.292-296
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• 2001

The Radix of Peucedanum japonicum (Umbelliferae) has been used for dispelling wind-damp, headache, chills and wind cold. In order to evaluate to quality of it, the method for the quantitative determination of peujaponiside $(peucedanol\;7-O-{\beta}-D-apiofuranosyl(1{\rightarrow}6)-{\beta}-D-glucopyranoside)$ as standard compound has been developed. Peujaponiside is a major compound of Peucedani Radix. It was analyzed by HPLC using the solvent system of 15% $CH_3CN$. The amount of peujaponiside from Peucedani Radix are in the range 0.14% (n=20).

• Korean Journal of Pharmacognosy
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• v.48 no.1
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• pp.88-92
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• 2017

In the present study, we carried out quantitative analysis of chrysin and pinocembrin in Korean propolis by ultra performance liquid chromatography (UPLC) equipped with diode array detector. The separation was done using BEH C18 ($2.1{\times}50mm$, $1.7{\mu}m$) column with a mobile phase consisting of MeCN and 0.1% $H_3PO_4$ at 280 nm. The chromatographic method was validated for specificity, limit of detection, limit of quantification, linearity, precision, and accuracy. A quantitative analysis exhibited that the contents of the two compounds in Korean propolis collected from 8 inland areas except Jeju-do ranged from 3.1-46.0 mg/g. These results will be valuable as basic data for standardization of Korean propolis.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.280-280
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• 2013

Using both experimentaland theoretical methods, we have investigated the structural and electronic properties of self-assembled two-dimensional organic molecule (hexaaza-triphenylene-hexacarbonitrile, HATCN), which is used as an efficient OLED hole injection material, on Au(111) surfaces. Low-temperature scanning tunneling microscope (STM) measurements revealed that self-assembled linear and hexagonal porous structures are formed at atomic steps and terraces of Au(111), respectively. We also found that the hexagonal porous structure have chirality and forms only small (＜1,000 nm2) phase-separated chiral domains that can easily change their chiral phase in subsequence STM images at 80 K. To explain these observations, we calculated the molecular-molecular and molecule-surface interaction energies by using first-principles density functional theory method. We found that the change of their chiral phase resulted from the competition between the two energies. These results have not only verified our experimental observations, but also revealed the delicate balance between different interactions that caused the self-assembed structures at the surface.

• Journal of the Korean Society of Combustion
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• v.15 no.4
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• pp.58-64
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• 2010

Spontaneous ignition tests of five different coals with non-iso-thermal and iso-thermal test method based on the standard test procedure of NF T20-036 were carried. These five coals included the 2 low rank coals and 3 bituminous coals. Test results showed that the ignition temperatures of all coals at the iso-thermal conditions were higher than that of non-isothermal condition, and those of low rank SM and BR coal in both nonisothermal and isothermal conditions were lower than bituminous AN and CN coals. The chemical species of coals such as oxygen and hematite also plays an important role in enhancing the ignition rate that the ignition temperature of SM coal was lowered. The heat accumulation tendency of five coals inside outdoor stack pile was monitored with emphasis on the change in the temperature of the coal depth in stack pile. In case of low rank BR coal, its temperature inside coal stack pile due to the rate of high heat accumulation and oxidation was $59^{\circ}C$ compared to $51^{\circ}C$ for other SW bituminous coal. And the heat accumulation rate inside coal stack piles was increased with increased the Cp value which it was defined as the specific heat of coal at constant pressure, whereas other factors such as thermal diffusivity and conductivity of coal relatively had less effect on heat accumulation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.183-187
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• 1997

The Thin films were obtained by plasma polymerization of phenyl isothiocyanate. Polymerizations were carried out in rf(13.56 [MHz]) glow discharge generated in an inter-electrode capacitively coupled gas flow system. It was fecund that this monomer produces uniform films with a wide range of thicknesses, from hundreds of nanometers to tens of micrometers. The deposition rate appeared to be dependent on the substrate distance from the monomer inlet. The IR data revealed significant decrease in -NCS groups content in the polymer as compared with the monomer spectrum and indicated for the appearance of new absorption bands corresponding to the -CN and C-H aliphatic groups. The soluble fraction by GC was found to be composed of numerous low molecular-weight compounds.

• Journal of Korean Academy of Nursing
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• v.34 no.3
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• pp.541-551
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• 2004

Purpose: This study was to identify the effects of the predictive factors of Internet addiction and to develop a predictive model that explains Internet addiction among adolescents in Korea. Method: Data was collected from 664 adolescents in Puasan and Ulsan. Data analysis was done using the SPSS 10.0 Win Program for descriptive and correlational statistics and the LISREL 8.53 Win Program for Covariance structural analysis. Result: The fit of the hypothetical model to the data was moderate, it was modified by deleting four paths. Compared to the hypothetical model, the revised one had a better fit to the data($\chi^2$/df=6.50, GFI=.99, AGFI=.90, RMR=.02, NNFI=.88, NFI=.98, CN=279). Gender, friend support, and loneliness had significant direct effects on Internet addiction. The direct and indirect effect of self-esteem on Internet addiction was significant. The indirect effect of family support on Internet addiction was significant but its direct effect was insignificant. The direct and indirect effects of stress and impulsiveness on Internet addiction were significant but their total effects were insignificant. Conclusion: Finally, to decrease loneliness, and to increase family support and self-esteem, an effective intervention program and education should be developed to prevent Internet addiction of adolescents.

• Korean Journal of Adult Nursing
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• v.18 no.2
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• pp.213-222
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• 2006

Purpose: This study was designed to construct a structural model for explaining model health-related quality of life in acquired people with physical disabilities. Method: The hypothetical model of this study was consisted of 6 latent variables and 14 observed variables. Exogenous variables included in this model were physical status and economical level. Endogenous variables were social attitudes, family function, self-esteem, and health-related quality of life. Data were collected from 226 acquired people with physical disabilities residing in Seoul and Kyunggi-do from January to February, 2005. The collected data were analyzed using SAS 8.2 version and LISREL 8.32 version program. Results: The results of the fitness test of the modified model were follow as; ${\chi}^2=67.479$ (df=50, p=.05), GFI=.959, AGFI=.914, SRMR=.049, NFI=.961, NNFI=.979, CN=249.244. Health-related quality of life was influenced directly by physical status, economic level, and social attitudes and accounted for 88.8% of the variance by these factors. Conclusion: These results suggest that physical status is the most significant effect on health-related quality of life, and social attitudes and economic level are important factors having influences on health- related quality of life. Therefore improving physical status and economic level, and modifying negative attitudes are necessary to increase health-related quality of life of acquired people with acquired physical disabilities.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.872-875
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• 2003

Carbon nitride($CN_x$) thin films were deposited on quartz substrates using reactive RF magnetron sputtering system at uarious deposition conditions and investigated dielectric characteristics. Samples for capacitance measurements were of the MIM(Metal-Insulator-Metal) type devices. Aluminum film electrodes were prepared by a vacuum thermal evaporation method before and after the deposition of carbon nitride films. Capacitances were measured by a FLUKE PM6306 RCL Meter at room temperature. Current-voltage(I-V) characteristics and resistivity were measured by a CATS CA-EDA semiconductor test and analyzer. The carbon nitride films showed ${\alpha}-C_3N_4$ and ${\beta}-C_3N_4$ etc. peaks through Raman and FTIR. Observed surface of film and side structure using SEM(Scanning Electron Microscope), and measured thickness of film by ${\alpha}-step$. We can find that the dielectric constant was the lowest value in 50% nitrogen ratio and the resistivity was the highest value in 70% nitrogen ratio.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.2
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• pp.209-217
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• 2014

Of several approaches for future Internet, separating two properties of IP address into locator and identifier, is being considered as a highly likely solution. IETF's LISP (Locator ID Separation Protocol) is proposed for this architecture. In particular, the LISP model easily allows for device mobility through simple update of information at MS (Mapping Server) without a separate protocol. In recent years, some of the models supporting device mobility using such LISP attributes have emerged; however, most of them have the limitation for seamless mobility support due to the frequent MS information updates and the time required for the updates. In this paper, PMIPv6 (Proxy Mobile IPv6) model is applied for mobility support in LISP model. PMIPv6 is a method that can support mobility based on network without the help of device; thus, this we define anew the behavior of functional modules (LMA, MAG and MS) to fit this model to the LISP environment and present specifically procedures of device registration, data transfer, route optimization and handover. In addition, our approach improves the communication performance using three tunnels identified with locators between mobile node and corresponding node and using a route optimized tunnel between MN's MAG and CN's MAG. Finally, it allows for seamless mobility by designing a sophisticated handover procedure.