• Journal of Korean Society of Environmental Engineers
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• v.39 no.7
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• pp.426-439
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• 2017

This review summarizes advantage and limitation in infrared spectroscopy and computational chemistry to understand rhizospheric interaction among organic acids, oxyanions and metal oxides. Since organic acids and metal oxides determine dynamics of oxyanions in the soil environment, knowledge of fundamental mechanisms is a prerequisite for understanding the interactions at soil-water interface. Attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR) is a powerful tool to measure the interfacial reactions. However, the ATR-FTIR measurements are abstruse, because the optical characteristics for measurements are variable depending on the experimental setup. In addition, spectral overlapping is a primary obstacle to the analysis of the interfacial reaction; thus, it is essential to detect and to deconvolute bands for signal interpretation. In this review, we expained the fundamental principle for spectrum processing, and four band identification methods, such as derivative spectroscopy, two-dimension correlation spectroscopy, multivariate curve resolution, and computational chemistry with example of aqueous phosphate speciation. As a result, spectrum processing and computational chemistry improved interpretation and spectral deconvolution of overlapped spectra in relatively simple systems, but it was still unsatisfactory for the problems in more complexed system like nature. Nevertheless, we believed that our challenge would contribute practically to develop adequate analytical procedure, signal processing and protocols that could help to improve interpretation and to understand the interfacial interactions of oxyanions in natural systems.

• Journal of the Korean Chemical Society
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• v.33 no.2
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• pp.185-191
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• 1989

Es wurden die Protonenspektren $wa{\beta}rigerH_2{^{17}}O$-haltige Erdalkalimetall-und Tetraalkylammoniumchlorid-Losungen bei $25^{\circ}$ und verschiededenen pH-Werten mit Hilfe der kernmagnetischen Resonanz-spektroskopie aufgenommen. Aus der Halbwertsbreite der Signale wurde die Austauschrate des Protons im Wassermolekul berechnet. Die Austauschrate, die in diesen Losungen beobachtet werden konnte, ist pH-abhangig. Bemerkernwerterweise ist die minimalle Austauschrate pH-abhangig. Dieses letztere Phanomen wird durch den Strukturbildungseffekt der Erdalkalimetallchloride und die hydrophobe Hydratation an Tetraalkylammoniumionen erklart.

• Korean Journal of Optics and Photonics
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• v.23 no.1
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• pp.36-41
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• 2012

Total external reflection (TER), which does not occur on a dielectric interface, is a unique feature of surface plasmon-polaritons (SPP). We propose an SPP-TER waveguide structure consisting of low-index dielectric nanocore covered with high-index dielectric on a flat metal surface. The SPP mode confined in the nanocore by the TER effect has a mode size much smaller than wavelength scale. Numerical comparison of mode characteristics between the SPP-TER waveguides and other total-internal-reflection-based waveguides such as metal or high-index dielectric nanowires show that the SPP-TER structures can possess higher modal gain for applications of nanocavity lasers.

• Journal of Practical Engineering Education
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• v.12 no.1
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• pp.203-212
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• 2020

This study surveyed 244 employees out of a total of 356 graduates from the steel industry in 2015 to February 2019. The employment rate of graduates is POSCO 67.7%, Hyundai Steel 23.8%, POSCO families 13.1%, and Hyundai Steel families 8.5%. The national certificates acquired by each section were surveyed, with 53.1% of metal section, 39.8% of mechanical section, and 7.1% of other section. Preferred national certificates were POSCO, machinery maintenance industry technicians, steelmaking technicians, and Hyundai Steel followed steelmaking technicians, mechanical maintenance industrial technicians. Among other certifications, the national certificate of industrial safety industrial engineer was preferred. In addition, the average number of national certificates per person for major employment is 5.06 for POSCO, 5.35 for POSCO families, 5.29 for Hyundai Steel, and 4.73 for Hyundai Steel families. The average number of national certificates for S-OIL, KEPCO, Poongsan Metal, etc., is 2.51. In conclusion, it was found that the national certificates related to majors are used as the main evaluation data in finding suitable majors and competency for the job when recruiting talents.

• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.441-448
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• 2016

Heavy metal removal study is conducted from synthetic waste water by reduction and oxidation(redox) reaction of Cu-Zn metal alloy and adsorption reaction of aluminium silicate. Heavy metal whose ionization tendency is smaller than zinc are reducted in an aqueous solution, and the concentration of ionized zinc is reduced by adsorption reaction. The average diameter of metal alloy micro fiber is about $200{\mu}m$, and the surface area is wide enough to get equilibrium in a single cycle treatment. A single cycle treatment of redox reaction of Cu-Zn metal alloy, could remove 100.0 % of Cr(III), 98.0 % of Hg, 92.0 % of Sn and 91.4 % of Cu respectively. An ionization tendency of chromium is very close to zinc, but removal efficiency of chromium by redox reaction is significant. This result shows that trivalent chromium ion is expected to generate hydroxide precipitation with $OH^-$ ion generated by redox reaction. Zinc ion generated by redox reaction is readily removed by adsorption reaction of aluminium silicate in a single cycle treatment. Other heavy metal components which are not perfectly removed by redox reaction also showed very high removal efficiency of 98.0 % or more by adsorption reaction. Aluminium ion is not increased by adsorption reaction of aluminium silicate. That means heavy metal ion removal mechanism by adsorption reaction is turned out to be not an ion exchange reaction, but an adsorption reaction.

• Conservation Science in Museum
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• v.11
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• pp.31-42
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• 2010

Here is an introduction of the conservation and making process of Seodae(Rank Belt with A Rhinoceros' Horn) of the Chuncheon National Museum. The seodae has a structure composed of wrapping fabric around a leather frame and decorated with ttidon(an ornament) made of a rhinoceros' horn and a metal frame. The adhesion between leather was weak and separation was taking place, parts of the horn were missing and the fabric was discoloring. Also the metal frame and the metal wire attaching ttidon were severly corroded. Nondestructive analysis was carried out by using a portable x-ray fluorescence spectroscopy to analyze the components of the metal parts. Conservation was carried out by dismantling parts and carrying out conservation process of each one according to material, then the parts were put back together.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.829-834
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• 1995

최근 전세계적으로 활발히 연구가 진행되고 있는 저준위 방사성폐기물 유리화에 관한 타당성을 조사하기 위해 여러 형태의 유리용융로에 대한 기술성을 분석하고, 기술성 분석에서 선택한 용융로를 이용한 3종류의 새로운 처리개념에 대한 경제성 분석을 수행하였다. 기술성 분석 대상 용융로는 프랑스 CEA/SGN 사의 직접유도가열식 저온로, 미국 VECTRA 사의 수직전극가열식 저온로, 미국 SEG사의 용응금속로 미국 Retech 사의 플라즈마토치 용융로이다. 기술성 분석결과 직접유도가 열식 저온로와 플라즈마토치 용융로를 병행하여 적용하는 것이 바람직하다는 결론을 얻었다. 이 용융로들을 이용한 3종류의 처리개념에 대해 처분부피, 처분단가에 따른 처분비, 처리비를 산정하고 현재 적용하고 있는 처리개념과 상호 비교하였다. 비교 결과 유리화 기술을 적용하는 것이 경제적이라 것과 현재 보다 80 %이상 처분부피를 감소시킬 수 있다는 것을 알 수 있었다.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.3
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• pp.264-271
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• 2017

Purpose: The purpose of this study is to investigate the differences in bond strength of four different indirect composites to the gold alloy and Ni-Cr alloy according to type of metal surface treatment after water storage. Materials and methods: Type IV gold alloy and Ni-Cr alloy were used for casting alloy while four types of indirect composite resins (Gradia, Tescera Sinfony and in;joy) were used in this study. Metal specimens were produced by casting and total of 240 specimens (60 specimens per one indirect composite group) were prepared. After bonding indirect composite resin and undergoing 24 hours of polymerization, customized jig was attached to the metal specimen and shear bond strength were measured using universal testing machine. Also, differences in shear bond strength before and after water storage for 240 hours were also measured. Results: In the measurement of shear bond strength according to the metal surface treatments, bead group showed high strength followed by loop and flatting group (P<.05). After being stored in water bath for 240 hours, Gradia showed statistically significant high bond strength compared to other indirect composite resins in all groups (P<.05). Conclusion: Shearbond strength was found to be different according to type of metal surface treatment and type of metal used after storage in water. Further studies need to be developed for clinical practices as three are still problems of microleakage, stain or wear.

• Conservation Science in Museum
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• v.4
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• pp.57-61
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• 2003

From the stupa of Sujongsa-Temple, located in Yangpyeong, Gyeonggi-do province, was excavated a celadon jar with lid, a gilt-bronze nine-storied miniature pagoda and a silver-plate hexagonal miniature shrine, etc. Among them, the gilt-bronze miniature pagoda has been known as a gilt-bronze product since most of its surface has copper tint and the base part has bronze corrosion. Its formal title registered on the Cultural Properties Administration also begins with "a gilt-bronze". However, it was supposed to be a gold product in many aspects: the color and status of the surface, degree of the bronze corrosion creation and the metal thread joining the wind bell. So the necessity to prove its material by a scientific analysis was raised. We examined it with nondestructive method. The results were traces of open-working on many parts of the surface, but no traces of gilding. Moreover, as we perform an XRF analysis, the main component were gold and silver(16%) and some impurities such as copper and iron were found. Therefore, it could be inferred that this miniature pagoda is a gold product.

• Applied Chemistry for Engineering
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• v.7 no.1
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• pp.109-117
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• 1996

Removal of metal ions on the ultrafiltration membrane with micellar-enhanced with anion surfactants is a recently developed technique which can remove heavy metals and small molecular weight ions from wastewater with simple separation process and without a phase change. Above a certain concentration, so called the critical micelle con binding cationic cobalt ions and anionic surfactants, were removed by ultrafiltration membrane. The transmembrane pressure difference had a relatively small effect on the rejection coefficient of metal ions on the ultrafiltration membrane whereas the level of anionic surfactant-to-metal ratio (S/M) had a substantial effect.