• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.6
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• pp.305-311
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• 2012

In order to recycle the coal bottom ashes (denoted as BA) produced from a thermal power plant, the artificial aggregates (denoted as AAs) containing BA and red clay were manufactured, and the physical properties of AAs were studied as a function of particle size of BA and batch compositions. As-received BA had 38 wt% coarse particles of above 2 mm and many unburned carbon mass and porous slag particles were co-existed. So the two particle sizes of BA, the fine (< 100 ${\mu}m$) and coarse (< 2 mm), were prepared by milling and screening process. The AAs containing fine BA sintered at $1100{\sim}1200^{\circ}C$ had the higher bulk density and lower water absorption compared to the specimen made of coarse BA. The inside core of AAs manufactured by using coarse BA showed nonuniform and porous microstructure, while the AAs made of fine BA had a uniform and dense microstructure. In this research, the AAs containing BA and red clay with various bulk density (1.2~1.7) and water absorption (13~21 %) could be manufactured by controlling the particle size of BA and batch compositions, so the AAs of various physical properties could be applied to the wide fields such as construction/building materials in near future.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.5
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• pp.216-220
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• 2010

Ni-Fe alloys have various applications such as thin film inductor, thin film transformer, magnetic head's shield case, etc. Magnetic properties of Ni-Fe thin films depend on the process parameters such as thickness, contents, deposition rate, substrates, etc. In this study, NiFe films with a thickness of about 150nm were deposited on Si(100) wafer and $SiO_2$/Si(100) substrate at room temperature by a DC magnetron co-sputtering using Fe and Ni targets. Their phase formation and magnetic properties as a function of annealing temperature were investigated with XRD, FE-SEM and VSM. The assputtered films have BCC structure. With increasing annealing temperature, NiFe thin film for $SiO_2$/Si(100) substrate transformed completely from BCC to FCC phase above $500^{\circ}C$, but some BCC phase remained above $500^{\circ}C$ on Si(100) wafer. For samples annealed at $450^{\circ}C$, squareness ratio of NiFe thin film shows peak value and its saturation magnetization is around 0.0118 emu, which means that the optimum annealing temperature of NiFe thin film seems to be $450^{\circ}C$. The saturation magnetization of films decreased rapidly above the annealing temperature of $500^{\circ}C$ due to phase transformation from BCC to FCC phase.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.5
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• pp.237-242
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• 2010

Magnesium-substituted BCP (biphasic calcium phosphate) powders were prepared by incorporating small amounts of magnesium into the structure of different hydroxyapatite (HAp)/${\beta}$-tricalcium phosphate (${\beta}$-TCP) ratios through coprecipitation method. A series of magnesium substitutions ranging from 0, 0.5, and 1.0 wt%, which are comparable to the measured magnesium contents, were performed. The obtained powders were characterized by the following analytical techniques: X-ray diffraction analysis (XRD), Thermo Gravimetric Analyzer (TGA) and Fourier transform infrared spectroscopy (FT-IR). The results have shown that substitution of magnesium in the calcium-deficient apatites resulted in the formation of biphasic mixtures of different HAP/${\beta}$-TCP ratios after heating above $1000^{\circ}C$. The 1.0 wt% magnesiumsubstituted-BCP were soaked in Hank's solutions after 2 weeks to observe the morphology of the biocement, especially needle-like hydroxyapatite crystals and to estimate the length and diameter of nanoneedle crystals.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.5
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• pp.193-200
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• 2016

Characteristics of $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphorescent phosphors synthesized by solid state reaction and polymerized complex method were comparatively analyzed. In order to evaluate thermal stability of $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphorescent phosphors at high temperature, phosphorescent properties of $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ were investigated with thermal treatment at $1250^{\circ}C$ under reducing atmosphere, which was the general heat treatment conditions for ceramic manufacturing process. The phosphorescent properties of thermally treated $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphors synthesized by solid state reaction and polymerized complex method were investigated. The crystal structure and crystallite size were observed through XRD analysis. Microstructure and particle size of thermally treated $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphors were analyzed by SEM and PSA. Photoluminescence and afterglow characteristics of thermally treated $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphorescent phosphors were measured by spectrofluorometer.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.3
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• pp.91-95
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• 2020

In this study, we report a hydrothermal synthesis in which BaTiO₃ nanoparticles (NPs) with enhanced size uniformity and dispersibility are synthesized by increased time and temperature, increasing nucleation and diffusion rates. The formation process of an uniform size of 20 nm BaTiO₃ NPs, which has not been extensively researched, was optimized through hydrothermal synthesis at 180℃. Simultaneous increase in the nucleation rate of TiO₂ and diffusion length of Ba²⁺ ions, resulting from a higher temperature, allowed for the synthesis of BaTiO₃ NPs (20 nm) with significantly enhanced size-uniformity. The size and crystallinity of BaTiO₃ NPs which exhibit excellent dispersibility in hexane solvent were investigated using transmission electron microscopy and X-ray diffraction. The results presented herein provide insights into improving the size uniformity and dispersibility of BaTiO₃ NPs by hydrothermal synthesis for applications to variety of electronic devices.

• Korean journal of communication and information
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• v.22
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• pp.107-130
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• 2003

This study evaluated the debate formats adopted in the 2002 Televised Presidential Debates. Presidential Debate Committee have sponsored Televised Presidential Debates during the official campaign period. However, it is not easy task for the Committee to coordinate each party's different interests, such as voters, candidates, and broadcasters. Presidential candidates tries to use the debates as one of their campaign strategies. Broadcasters argued limitations in programming and production process. Regardless of the obstacles, voters expect that the committee makes ideal debate formats. The committee adopted two new forms in the 2002 Debates. The committee allowed direct exchange between candidates as well as advance question preparation by candidate. The committee intends that candidates focus on discussing policy issues. Some studies found that the debate format to allow direct exchange between candidates makes candidates focus on image issues rather than policy issues. The findings of this study are similar to the previous studies'. The new debate formats adopted in 2002 televised presidential debates did not guarantee policy issue oriented discussion. The committee or scholars should evaluate the debate formats used in the presidential debates in order to establish ideal debate formats that gives important information for votes to determine their choice. It is necessary to systematically evaluate the debate formats of former presidential campaign for developing right debate formats.

• Korean journal of communication and information
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• v.25
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• pp.65-102
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• 2004

The purpose of this study was to examine the news attributes of the nuclear waste storage facility in Wido by conducting content analysis of two newspapers (Chosun Ilbo and Hangyoreh) and Ohmynews. Furthermore, this study measured the effects of news attributes on readers' attitude, opinion, and recognition of the event. The results of the content analysis indicated that all three newspapers focused on event-oriented coverage than issue-oriented one. Also, they only dealt with two issues-decision making process of the residents and rewards for residents-among a total of nine issues. That is, according to the hypothesis of the second-level agenda-setting theory, the media emphasize on a particular attribute while ignoring other attributes, which, in turn, make the particular attributes more salient. Based on the results of content analysis, this study conducted an experiment to measure the effects of media attributes on public recognition toward the attributes in terms of cognitive and of affective aspects. The results showed a significant relationship between media attributes and public attributes, which confirmed the effects of the second-level agenda setting. However, the transfer of attributes did not take place in affecting public opinion and public recognition of the event itself.

• Korean journal of communication and information
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• v.25
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• pp.103-133
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• 2004

Korean citizens enjoy not only the freedom of communication but also the secrecy of electronic communication. Article 18 of the Constitution of the Republic of Korea prescribes that the secrecy of correspondence should not be infringed. Namely, all citizens enjoy guaranteed privacy of correspondence. But many people have been experiencing the infringement of those rights. The purpose of this paper is to evaluate whether Paragraph 2, Article 13 of the Act on Protection of the Secrecy of Correspondence infringes on the constitutional rights of privacy of electronic communication. The results of this study indicate that the law violates the Constitution. Paragraph 3, Article 12 (Personal Liberty, Personal Integrity) of the constitution stipulates that "Warrants issued by a judge through due process (upon the request of a prosecutor) have to be presented in case of arrest, detention, seizure, or search." However, prosecutors, the police, and National Intelligence Service have made numerous inquiries calling for the journalists' telephone records without warrants issued by a judge. So, this study suggests that the paragraph should be amended to be compatible with the Constitution. Meanwhile, journalists should make a more concerted effort to protect their news sources in exercising constitutionally protected freedom of the press.

• Korean journal of communication and information
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• v.71
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• pp.116-154
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• 2015

Officially given a historical signifier as Gwangju Democratic Movement since 1987, far-right and conservative group have restated that $5{\cdot}18$ is a rebellion and a riot that was committed by rebellious elements who obeyed North Korea's command or who were connected with North Korea. As those who had been responsible for the rebellion, revolt and riot were rewarded, far-right and conservatives' collective narrative that a country was born where the pro-North Korea left became dominated aroused extreme hostility towards $5{\cdot}18$. Far-right and conservatives involved in many different fields such as political party, university, press and media and civil group carry out incendiary discourse politics with intention to reestablish history and memory of $5{\cdot}18$ in their own story. Many people at online sites such as Ilbe Storehouse who are considered 'young right wing' is a main route to spread the far-right groups' remarks on $5{\cdot}18$. Ilbe is a main channel to reconstitute and reproduce the far-right conservatives' remarks and information on $5{\cdot}18$. Ilbe is one of main area where remarks of disparagement and ridicule, hostility and hatred on $5{\cdot}18$ unfurl. This study collects $5{\cdot}18$-related remarks and stories unfolded at Ilbe and examines how these remarks and stories make significance as to $5{\cdot}18$ and how information resources which remarks are dependent upon are connected each other. In this process, this study intends to find implications of incendiary politics that echoed of remarks on $5{\cdot}18$ have which at the online site Ilbe and by the far-right conservatives.

• Korean journal of communication and information
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• v.75
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• pp.9-42
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• 2016

This study critically examines the social and personal meanings that luxury consumption have in contemporary Korean society through understanding the consumption experiences of men in their 30s. Interviews with nine male consumers who are committed to luxury brands, especially those that produce suits, watches, fountain pens, and shoes, were conducted to collect qualitative data. We found that participants are satisfied with the whole process of luxury brand consumption including buying, using, and managing and try to consume the products for self-expression, congruent with their lifestyle and identity. Individuals have learned how to consume the luxury brand from their role models. Their consumption follows hybrid and postmodern patterns and combines luxury brand products with non-luxury one. In contemporary Korean society, using the luxury products is considered necessary to achieve some advantages in social contexts and can be also functioned as a sort of social signifier and self-help, as well as, a tool for self satisfaction or well-being.