• Journal of the Society of Cosmetic Scientists of Korea
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• v.50 no.2
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• pp.143-151
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• 2024

Ozone is a colorless, toxic gas that is produced when nitrogen oxides and hydrocarbons undergo a photochemical oxidation reaction in the sun's rays. Even at low concentrations, it affects the respiratory system, causing coughing and other harmful effects. It was confirmed that ozone was generated from nitrogen plasma among cosmetic raw materials, and it was found that the concentration of ozone decreased after 1 day. On the other hand, ozone was not detected in ozone-free plasma generated with argon gas. Therefore, we aimed to produce ozone-free cosmetics by utilizing ozone-free plasma. For efficient plasma processing, the non-sinking method was utilized to inject the plasma into layer separation mists, toners, and ampoules, and the stability was observed. It was found that the successful injection of plasma in the layer separation mist was higher than the other two formulations, but decreased sharply compared to the toner and ampoule. It was found that the ozone-free plasma used did not affect the stability of the layer separation mist, toner, and ampoule under low temperature (4 ℃), room temperature (25 ℃), and high temperature (37 ℃, 50 ℃) conditions. Therefore, this study suggests the importance of ozone-free plasma for cosmetic potential and stability of each formulation.

• Applied Chemistry for Engineering
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• v.25 no.5
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• pp.455-462
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• 2014

This work investigated the hydrophobic coating of silicate yellow phosphor powder in the form of divalent europium-activated strontium orthosilicate ($Sr_2SiO_4:Eu^{2+}$) by using an atmospheric pressure dielectric barrier discharge (DBD) plasma with argon as a carrier and hexamethyldisiloxane (HMDSO), toluene and n-hexane as precursors. After the plasma treatment of the phosphor powder, the lattice structure of orthosilicate was not altered, as confirmed by an X-ray diffractometer. The coated phosphor powder was characterized by scanning electron microscopy, fluorescence spectrophotometry and contact angle analysis (CAA). The CAA of the phosphor powder coated with the HMDSO precursor revealed that the water contact angle increased from $21.3^{\circ}$ to $139.5^{\circ}$ (max. $148.7^{\circ}$) and the glycerol contact angle from $55^{\circ}$ to $143.5^{\circ}$ (max. $145.3^{\circ}$) as a result of the hydrophobic coating, which indicated that hydrophobic layers were successfully formed on the phosphor powder surfaces. Further surface characterizations were performed by Fourier transform infrared spectroscopy and X-ray photoelectron spectrometry, which also evidenced the formation of hydrophobic coating layers. The phosphor coated with HMDSO exhibited a photoluminescence (PL) enhancement, but the use of toluene or n-hexane somewhat decreased the PL intensity. The results of this work suggest that the DBD plasma may be a viable method for the preparation of hydrophobic coating layer on phosphor powder.

• Journal of the Korean Magnetics Society
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• v.7 no.2
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• pp.90-96
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• 1997

We have studied crystallographic and magnetic properties of $NdFe_{10.7}Ti_ {1.2}Mo_{0.1}$ by Mossbauer spectroscopy, X-ray diffraction and vibrating sample magnetometer (VSM). The alloys were prepared by arc-melting under an argon atmosphere. The $NdFe_{10.7}Ti_{1.2}Mo_{0.1}$ has pure a single phase, whereas $NdFe_{10.7}Ti_{1.3}$ contains some $\alpha$-Fe, conformed with X-ray diffractometry and Mossbauer measurements. The $NdFe_{10.7}Ti_ {1.2}Mo_{0.1}$ has a $ThMn_{12}-type$ tetragonal structure with $a_0=8.637{\AA}$ and $c_0=4.807{\AA}$. The Curie temperature ($T_c$) is 600 K from the result of Mossbauer measurement performed at various temperatures ranging from 13 to 800 K. Each spectrum of below $T_c$ is fitted with five subspectra of Fe sites in the structure ($8i_1, 8i_2, 8j_2, 8j_1, 8f$). The area fractions of the subspectra at room temperature are 12.3%, 14.0%, 21.0% 11.8%, 40.9%, respectively. Magnetic hyperfine fields for the Fe sites decrease in the order, $H_{hf}(8i)>H_{hf}(8j)>H_{hf}(8f)$. The abrupt changes in the magnetic hyperfine field, an magnetic moment observed at about 160 K in $NdFe_ {10.7} Ti_{1.2}Mo_{0.1}$ are attributed to spin reorientations. The average hyperfine field of the $NdFe_{10.7}Ti_{1.2}Mo_{0.1}$ shows a temperature dependence of $[H_{hf}(T)-H_{hf}(0)]/H_{hf}(0)=-0.34(T/T_C)^{3/2}-0.14(T/T_C)^{5/2}$ for $T/T_c<0.7$, indicative of spin wave excitation. The Debye temperatures of $NdFe_{10.7}Ti_{1.2}Mo_{0.1}$ is found to be Θ=340$\pm$5 K.

• Economic and Environmental Geology
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• v.35 no.6
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• pp.523-532
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• 2002

The rare earth elements (REE) and Nd, Sr and noble gas isotopic compositions eHer'He, 4$^{\circ}$Arp6Ar) for the Quaternary alkali basaltic rocks and mantle xenoliths in the basaltic rocks from the Baegryongdo were investigated to decipher the origin of alkali basaltic magma and xenolith beneath the Sino-Korean craton. Analytical results are summarized as follows; (1) The alkali volcanic rocks with voluminous xenoliths which are represented by the Mg-olivine and clinopyroxene dominant spinel-lherzolite in the Baegryongdo consist mainly of the basalt-mugearite and basaltic andesite. (2) The REE pattern of alkali basaltic rocks characterized by high HREE is similar to that of oceanic island basalt (OlB). Relatively concordant REE patterns of the basaltic rocks suggest that the alkali basaltic magma be formed by the identical source materials. (3) The Nd-Sr isotopic data of the alkali basaltic rocks suggest that the alkali basaltic magma be originated from the depleted mantle source with a little contamination of the continental crustal materials. (4) The $^3$He/ $^4$He ratios in olivines of xenoliths ranging from 5.0${\pm}$1.lRa to 6.7${\pm}$1.3Ra are lower than that of MORB (ca. 8.0Ra). It suggest that the xenolith be derived from the subcontinental lithospheric mantle. However, the high $^3$Her'He value of 16.8${\pm}$3.IRa at 1800$^{\circ}$C fraction (sample no OL-7) might be resulted from the post-eruptive cosmogenic $^3$He. The 4OAr/ 36 Ar ratios in olivines of mantle xenoliths are comparable to that of atmospheric argon, and are much lower than that of the MORB type mantle. These facts can lead to conclusion that the olivine of the xenolith in the Baegryongdo is affected by the post-eruptive atmospheric contamination during the slow degassing process.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.16-24
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• 2001

The purpose of this study was to evaluate the specificity, sensitivity, and diagnostic power of caries activity test using laser fluorescence. The subjects of this study were 50 children of $7\sim9$ years old. Fluorescence from initial carious lesion of teeth illuminated by an argon laser(480nm) was observed and photographed with barrier filter. Visual examination for the dDfFtT rate and Streptococcus mutans colony counting was done to evaluate correlation with caries activity test using laser fluorescence. Data analysis was accomplished by Axelsson's method. The results from the present study can be summarized as follows: 1. There was positive correlation $(\gamma=0.48)$ between laser fluorescence test and Streptococcus mutans count. And also positive correlation $(\gamma=0.39)$ exists between laser fluorescence test and dDfFtT rate (P<0.01). 2. Positive correlation $(\gamma=0.27)$ between Streptococcus mutans colony count and dDfFtT rate was found(P<0.05). 3. When dDfFtT rate was defined to standard testing method, the specificity, senstivity, and diagnostic power of laser fluorescence test were 44.4%, 85.7%, and 87.8%. 4. When dDfFtT rate was defined to standard testing method, the specificity, senstivity, and diagnostic power of S. mutans colony counting were 77.8%, 92.9%, 84.8%. 5. When S. mutans colony counting was defined to standard testing method, sensitivity, specificity and diagnostic power of laser fluorescence test were 40.0%, 84.8%, 95.1%. In regard to above results, laser fluorescence test considered to be accurate and reliable method for determining caries activity because of it's close relationship with caries susceptibility test and caries experience measurements. And it was also considered to be practical because it would be simple, inexpensive, and time saving method.

• Tuberculosis and Respiratory Diseases
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• v.64 no.4
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• pp.272-277
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• 2008

Background: The efficacy of the use of the interventional bronchoscope for palliation of patients with central airway obstruction has been established. In the palliative setting to alleviate central airway obstruction, the use of laser resection, electrocautery, argon plasma coagulation, photodynamic therapy and cryotherapy can provide relief of an airway obstruction. Cryotherapy is the therapeutic application of extreme cold for the local destruction of living tissue. Recently, this technique has been used for endoscopic management of central airway obstructions in Korea. We report the role and complications of the use of cryotherapy for airway obstructions in patients with advanced lung cancer. Methods: We used a flexible cryoprobe for cryotherapy using nitrous oxide as a cryogen. The cryoprobe was applied through the working channel of a flexible fiberoptic bronchoscope. The temperature of the tip was approximately $-89^{\circ}C$, and the icing time was 5~20 seconds. Results: Four patients with a central airway obstruction from advanced lung cancer were treated with cryotherapy. Three of the four patients were treated successfully and the airway obstruction was improved after the cryotherapy procedure. Dyspnea, hypoxia and atelectais were improved in three cases. Two patients experienced complications- one patient experienced pneumomediastinum and the other patient experienced massive hemoptysis during the cryotherapy procedure. However, these complications resolved and did not influence mortality. Conclusion: This technique is effective and relatively safe for palliation of inoperable advanced lung cancer with a central airway obstruction.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.2
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• pp.51-55
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• 2015

The present research is focused on the effect of porous graphite what is influenced on the 4H-SiC crystal growth by PVT method. We expect that it produces more C-rich and a change of temperature gradient for polytype stability of 4H-SiC crystal as adding the porous graphite in the growth cell. The SiC seeds and high purity SiC source materials were placed on opposite side in a sealed graphite crucible which was surrounded by graphite insulator. The growth temperature was around $2100{\sim}2300^{\circ}C$ and the growth pressure was 10~30 Torr of an argon pressure with 5~15 % nitrogen. 2 inch $4^{\circ}$ off-axis 4H-SiC with C-face (000-1) was used as a seed material. The porous graphite plate was inserted on SiC powder source to produce a more C-rich for polytype stability of 4H-SiC crystal and uniform radial temperature gradient. While in case of the conventional crucible, various polytypes such as 6H-, 15R-SiC were observed on SiC wafers, only 4H-SiC polytype was observed on SiC wafers prepared in porous graphite inserted crucible. The defect level such as MP and EP density of SiC crystal grown in the conventional crucible was observed to be higher than that of porous graphite inserted crucible. The better crystal quality of SiC grown using porous graphite plate was also confirmed by rocking curve measurement and Raman spectra analysis.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.111-112
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• 2009

Diamond-like carbon (DLC) is a convenient term to indicate the compositions of the various forms of amorphous carbon (a-C), tetrahedral amorphous carbon (ta-C), hydrogenated amorphous carbon and tetrahedral amorphous carbon (a-C:H and ta-C:H). The a-C film with disordered graphitic ordering, such as soot, chars, glassy carbon, and evaporated a-C, is shown in the lower left hand corner. If the fraction of sp3 bonding reaches a high degree, such an a-C is denoted as tetrahedral amorphous carbon (ta-C), in order to distinguish it from sp2 a-C [2]. Two hydrocarbon polymers, that is, polyethylene (CH2)n and polyacetylene (CH)n, define the limits of the triangle in the right hand corner beyond which interconnecting C-C networks do not form, and only strait-chain molecules are formed. The DLC films, i.e. a-C, ta-C, a-C:H and ta-C:H, have some extreme properties similar to diamond, such as hardness, elastic modulus and chemical inertness. These films are great advantages for many applications. One of the most important applications of the carbon-based films is the coating for magnetic hard disk recording. The second successful application is wear protective and antireflective films for IR windows. The third application is wear protection of bearings and sliding friction parts. The fourth is precision gages for the automotive industry. Recently, exciting ongoing study [1] tries to deposit a carbon-based protective film on engine parts (e.g. engine cylinders and pistons) taking into account not only low friction and wear, but also self lubricating properties. Reduction of the oil consumption is expected. Currently, for an additional application field, the carbon-based films are extensively studied as excellent candidates for biocompatible films on biomedical implants. The carbon-based films consist of carbon, hydrogen and nitrogen, which are biologically harmless as well as the main elements of human body. Some in vitro and limited in vivo studies on the biological effects of carbon-based films have been studied [$2{\sim}5$].The carbon-based films have great potentials in many fields. However, a few technological issues for carbon-based film are still needed to be studied to improve the applicability. Aisenberg and Chabot [3] firstly prepared an amorphous carbon film on substrates remained at room temperature using a beam of carbon ions produced using argon plasma. Spencer et al. [4] had subsequently developed this field. Many deposition techniques for DLC films have been developed to increase the fraction of sp3 bonding in the films. The a-C films have been prepared by a variety of deposition methods such as ion plating, DC or RF sputtering, RF or DC plasma enhanced chemical vapor deposition (PECVD), electron cyclotron resonance chemical vapor deposition (ECR-CVD), ion implantation, ablation, pulsed laser deposition and cathodic arc deposition, from a variety of carbon target or gaseous sources materials [5]. Sputtering is the most common deposition method for a-C film. Deposited films by these plasma methods, such as plasma enhanced chemical vapor deposition (PECVD) [6], are ranged into the interior of the triangle. Application fields of DLC films investigated from papers. Many papers purposed to apply for tribology due to the carbon-based films of low friction and wear resistance. Figure 1 shows the percentage of DLC research interest for application field. The biggest portion is tribology field. It is occupied 57%. Second, biomedical field hold 14%. Nowadays, biomedical field is took notice in many countries and significantly increased the research papers. DLC films actually applied to many industries in 2005 as shown figure 2. The most applied fields are mold and machinery industries. It took over 50%. The automobile industry is more and more increase application parts. In the near future, automobile industry is expected a big market for DLC coating. Figure 1 Research interests of carbon-based filmsFigure 2 Demand ratio of DLC coating for industry in 2005. In this presentation, I will introduce a trend of carbon-based coating research and applications.

• Economic and Environmental Geology
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• v.41 no.1
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• pp.15-32
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• 2008

The hydrochemical and isotopic (stable isotopes and noble gas isotopes) analyses for hot spring waters, cold groundwaters and surface water samples from the Seokmodo hot spring area of the Ganghwa province were carried out to characterize the hydrogeochemical characteristics of thermal waters and to interpret the source of thermal water and noble gases and the geochemical evolution of hot spring waters in the Seokmodo geothermal system. The hot spring waters and groundwaters show a weakly acidic condition with the pH values ranging from 6.42 to 6.77 and 6.01 to 7.71 respectively. The outflow temperature of the Seokmodo hot spring waters ranges from $43.3^{\circ}C\;to\;68.6^{\circ}C$. Relatively high values of the electrical conductivities which fall between 60,200 and $84,300{\mu}S/cm$ indicate that the hot spring waters were mixed with seawater in the subsurface geothermal system. The chemical compositions of the Seokmodo hot spring waters are characterized by Na-Ca-Cl water type. On the other hand, cold groundwaters and surface waters can be grouped into three types such as the Na(Ca)-$HCO_3$, Na(Ca)-$SO_4$ and Ca-$HCO_3$ types. The ${\delta}^{18}O\;and\;{\delta}D$ values of hot spring waters vary from -4.41 to -4.47%o and -32.0 to -33.5%o, respectively. Cold groundwaters range from -7.07 to -8.55%o in ${\delta}^{18}O$ and from -50.24 to -59.6%o in ${\delta}D$. The oxygen and hydrogen isotopic data indicate that the hot spring waters were originated from the local meteoric water source. The enrichments of heavy isotopes ($^{18}O\;and\;^2H$) in the Seokmodo hot spring waters imply that the thermal water was derived from the diffusion Bone between fresh and salt waters. The ${\delta}^{34}S$ values ranging from 23.1 to 23.5%o of dissolved sulfate are very close to the value of sea water sulfate of ${\delta}^{34}$S=20.2%o in this area, indicating the origin of sulfate in hot springs from sea water. The $^3H/^4He$ ratio of hot spring waters varies from $1.243{\times}10^{-6}\;to\;1.299{\times}10^{-6}cm^3STP/g$, which suggests that He gas in hot spring waters was partly originated from a mantle source. Argon isotopic ratio $(^{40}Ar/^{36}Ar=298{\times}10^{-6}cm^3STP/g)$ in hot spring waters corresponds to the atmospheric value.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.4
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• pp.228-232
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• 2006

Purpose: electrophilic $^{18}F(T_{1/2}=110\;min)$ radionuclide in the form of $[^{18}F]F_2$ gas is of great significance for labeling radiopharmaceuticals for positron omission tomography (PET). However, its production In high yield and with high specific radioactivity is still a challenge to overcome several problems on targetry. The aim of the present study was to develop a method suitable for the routine production of $[^{18}F]F_2$ for the electrophilic substitution reaction. Materials and Methods: The target was designed water-cooled aluminum target chamber system with a conical bore shape. Production of the elemental fluorine was carried out via the $^{18}O(p,n)^{18}F$ reaction using a two-step irradiation protocol. In the first irradiation, the target filled with highly enriched $^{18}O_2$ was irradiated with protons for $^{18}F$ production, which were adsorbed on the inner surface of target body. In the second irradiation, the mixed gas ($1%[^{19}F]F_2/Ar$) was leaded into the target chamber, fellowing a short irradiation of proton for isotopic exchange between the carrier-fluorine and the radiofluorine absorbed in the target chamber. Optimization of production was performed as the function of irradiation time, the beam current and $^{18}O_2$ loading pressure. Results: Production runs was performed under the following optimum conditions: The 1st irradiation for the nuclear reaction (15.0 bar of 97% enriched $^{18}O_2$, 13.2 MeV protons, 30 ${\mu}A$, 60-90 min irradiation), the recovery of enriched oxygen via cryogenic pumping; The 2nd irradiation for the recovery of absorbed radiofluorine (12.0 bar of 1% $[^{19}F]fluorine/argon$ gas, 13.2 MeV protons, 30 ${\mu}A$, 20-30 min irradiation) the recovery of $[^{18}F]fluorine$ for synthesis. The yield of $[^{18}F]fluorine$ at EOB (end of bombardment) was achieved around $34{\pm}6.0$ GBq (n>10). Conclusion: The production of $^{18}F$ electrophilic agent via $^{18}O(p,n)^{18}F$ reaction was much under investigation. Especially, an aluminum gas target was very advantageous for routine production of $[^{18}F]fluorine$. These results suggest the possibility to use $[^{18}F]F_2$ gas as a electrophilic substitution agent.