• 대한화학회지
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• 제56권1호
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• pp.34-46
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• 2012

Dopants and defects can be introduced as well as the intercalation of metals into single wall carbon nanotubes (SWCNTs) to modify their electronic and magnetic properties, thus significantly widening their application areas. Through spinpolarized density functional theory (DFT) calculations, we have systemically studied the following: (i) (10,0) and (5,5) SWCNT doped with nitrogen ($CN_xNT$), (ii) (10,0) and (5,5) SWCNT with pyridine-like defects (3NV-$CN_xNT$), and (iii) chemical functionalization of (10,0) and (5,5) 3NV-$CN_xNT$ with 12 different transition metals (TMs) (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, and Pt). Attention was done in searching for the most stable configurations, deformation, calculating the formation energies, and exploring the effects of the doping concentration of nitrogen and pyridine-like nitrogenated defects on the electronic properties of the nanotubes. Also, calculating the corresponding binding energies and effects of chemical functionalization of TMs on the electronic and magnetic properties of the nanotubes has been made. We found out that the electronic properties of SWCNT can be effectively modified in various ways, which are strongly dependent not only on the concentration of the adsorbed nitrogen but also to the configuration of the adsorbed nitrogen impurities, the pyridine-like nitrogenated defects, and the TMs absorbed; due to the strong interaction between the d orbitals of TMs and the p orbitals of N atoms, the binding strengths of TMs with the two 3NV-$CN_xNT$ are significantly enhanced when compared to the pure SWCNTs.

• Structural Engineering and Mechanics
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• 제65권5호
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• pp.535-546
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• 2018

The objective of this study is to understand the behaviour of hollow core slabs strengthened with FRP and hybrid techniques through numerical and analytical studies. Different strengthening techniques considered in this study are (i) External Bonding (EB) of Carbon Fiber Reinforced Polymer (CFRP) laminates, (ii) Near Surface Mounting (NSM) of CFRP laminates, (iii) Bonded Overlay (BO) using concrete layer, and (iv) hybrid strengthening which is a combination of bonded overlay and NSM or EB. In the numerical studies, three-dimensional Finite Element (FE) models of hollow core slabs were developed considering material and geometrical nonlinearities, and a phased nonlinear analysis was carried out. The analytical calculations were carried out using Response-2000 program which is based on Modified Compression Field Theory (MCFT). Both the numerical and analytical models predicted the behaviour in agreement with experimental results. Parametric studies indicated that increase in the bonded overlay thickness increases the peak load capacity without reducing the displacement ductility. The increase in FRP strengthening ratio increased the capacity but reduced the displacement ductility. The hybrid strengthening technique was found to increase the capacity of the hollow core slabs by more than 100% without compromise in ductility when compared to their individual strengthening schemes.

• 말소리와 음성과학
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• 제1권2호
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• pp.119-128
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• 2009

Many researchers have argued about the relationship between information structure and intonation. Their results can be summarized in three main points: the intonation of topic and focus in English information structures is implemented as i) a pitch accent, ii) a tune (a pitch accent + (an) edge tone(s)), or iii) a boundary tone. The purpose of this paper is to study various intonational patterns of topic and focus in English information structures, using natural conversations. In this paper, the types of topics and foci are divided, based on contrastiveness. The topics are classified as five non-contrastive and four contrastive topics. The foci are classified as neutral focus, informational focus, and contrastive focus. The results show that the intonation of the topic in English information structures is mainly implemented as a pitch accent, except for the type of the pronoun topic (Lp) which is not implemented as a pitch accent or a tune. However, the intonation of the focus is implemented as a tune in the neutral focus (Fn) and as a pitch accent or a tune in the informational focus (Fi) and the contrastive focus (Fe). In our discussion and conclusion, we suggest that it is not always true that for the meaning of contrast, the topic or the focus is represented as a $L+H^{\ast}$ pitch accent, which has been the main contrastive intonation from earlier studies.

• 천문학회보
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• 제38권2호
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• pp.54-54
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• 2013

We performed spectroscopic and photometric monitoring observations of a QSO, PG0934+013 for a reverberation-mapping analysis, using the 9-m Southern African Large Telescope (SALT) for spectroscopy and the 2-m Faulkes Telescope North and the South for photometry. The monitoring campaign was carried out for 5 month between December 2012 to April 2013, providing 20 spectroscopic epochs and ~40 photometric epochs. Based on the obtained spectra, which typically have a signal-to-noise ratio to 30-60, we performed multicomponent decomposition using various components, i.e., power-law continuum, FeII emission complex, and broad and narrow emission lines, to properly measure the Hbeta line flux. After a flux normalization using [O III] 5007 line luminosity, we obtained a rms spectrum from all epochs, which shows clear variability of Hbeta line. We find that Hbeta line flux decreases by ~20% during the monitoring period while the continuum flux obtained from the aperture photometry based on the imaging data, shows similar variability. The current Hbeta light curve shows monotonic decrease and a reliable cross correlation analysis between Hbeta and continuum light is difficult. Nevertheless, we obtained a preliminary lag measurements as ~24 light days.

• 천문학회보
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• 제38권2호
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• pp.38.1-38.1
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• 2013

We present the Yonsei evolutionary population synthesis (YEPS) models based on the high-resolution empirical spectral energy distributions (SEDs). We have adopted the MILES library in the optical wavelength, and our new models based on the MILES library show good agreements with our previous models presented in the YEPS I. The effect of hot horizontal-branch (HB) stars on the integrated properties of simple stellar populations (SSPs) is again confirmed by our models based on empirical SEDs. In addition, we have extended our empirical models to the near-IR wavelength and predicted the strengths of the calcium II triplet (CaT) and the Paschen triplet (PaT) based on the INDO-US and the Cenarro library. We find that the effect of HB stars and the age of SSPs on the CaT is almost negligible. On the other hands, the PaT models are very sensitive to the existence of hot stars, e.g., HB stars and young turn-off stars, and show very similar results with Balmer lines. Interestingly, the CaT distribution of GCs in NGC 1407, which is at odds with the optical (B-I) color distribution, can be explained by the unique feature of the CaT-[Fe/H] relations that show almost the same equivalent widths in the metal-rich regime. We will also discuss the impact of the second-generation populations on the strength of the CaT.

• 자원환경지질
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• 제19권2호
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• pp.85-96
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• 1986

The Bupyeong Silver mine which is located approximately 35km west of Seoul is currently the leading silver producer in Korea. The deposits occur as stockwork deposits hosted in Jurassic pyroclastic rocks. Occurrences of ore deposits and mineral paragenesis suggest a division of mineralization into four stages: Stage I, deposition of iron oxide and base metal sulfides; Stage II, deposition of tin oxide and silverm inerals; stage III, deposition of native silver and other silver minerals; Stage IV, formation of pyrite bearing siderite veinlets, Silver minerals in ore are native silver, argentite, freibergite, pyrargyrite, canfieldite, polybasite, dyscrasite and Ag-Fe-S mineral. The most important silver mineral is native silver among them. Chemical composition of important silver minerals were determined by electron probe microanalyser. Assay, size and modal analyses for floatation products were carried out. In floatation products, relative proportion of native silver for total important silver minerals have following ranges: feed, 64.7 to 74.74 wt.%; A-cleaner concentrate, 80.58 to 98.79 wt.%; and final tailing, 28.12 to 72. 57 wt. %. Average degree of liberation for native silver in feed and A-cleaner concentrate are 60.49% and 77.57% respectively. Negative relationship can be recognized between native silver and argentite in their abundance and behavior in floatation precesses.

• 한국식품저장유통학회:학술대회논문집
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• 한국식품저장유통학회 2003년도 춘계총회 및 제22차 학술발표회
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• pp.121.1-121
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• 2003

증류수, 수도수, 온천수(경산 사이판 온천) 희석액 (55배 희석; I, 4배 희석; II, 2배희석; III을 사용한 반죽의 발효와 빵의 품질에 미치는 영향을 조사하였다. 경산사이판 온천수는 총고형물이 8,765 ppm 이였으며 주요 무기질로는 Na가 2296 ppm, Ca가 287 ppm, Mg와 K가 각각 65 및 8 ppm을 함유하였다. Fe, Cu, Co, F. Zn Al, S, Mo, Se 및 Si 등이 0.002~5.2 ppm을 함유하였다. 온천수를 사용한 반죽의 pH는 6.95~7.68로 증류수의 6.40보다 높았다. 반죽부피는 온천수의 농도가 높아짐에 따라 감소하였다. pH를 5.5로 조정한 온천수를 사용한 반죽의 부피는 대조구 보다 오히려 높았다. 온천수를 사용한 빵의 경도 (hardness)와 신장성(strength)는 대조구 보다 높았으나 pH를 조정한 온천수의 경우는 낮았다. 점착성은 경도 및 신장성과는 역으로 희석 온천수에서 낮았다. pH 조정 없이 구운 빵의 부드러운 정도는 4배로 희석한 온천수가 증류수 및 55배, 2배 희석 온천수보다 높았다. 쫄깃한 맛도 온천수가 대조구에 비하여 높았으며 종합적인 기호도는 4배 희석 온천수가 가장 좋았다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
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• pp.307-311
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• 2006

Chemical analyses were conducted for Nakdong River water and riverbank filtrate in Daesan-Myeon area, Changwon City in 2005. Chemical components show different trends in wet season (June, July, August and September) and dry season (the other months). The patterns of chemical variation are classified into four types. Chemical components belonging Type I, as Na and $HCO_3$, show decrease in concentration during wet season and increase in concentration during dry season for both Nakdong River water and the riverbank filtrate. Chemical components belonging Type II, as Mg and $SO_4$, show decrease in concentration during wet season and increase in concentration during dry season for Nakdong River water while show the opposite trend for the riverbank filtrate. Chemical components belonging Type III, as Cl and $NO_3$, show increase in concentration from the start of wet season and high concentration during dry season for both Nakdong River water and the riverbank filtrate. Chemical components belonging Type IV, as Fe, show increase in concentration during wet season and decrease in concentration during dry season for both Nakdong River water and the riverbank filtrate.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.563-564
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• 2014

Recent developments in the prediction of the contribution of windnoise to the interior SPL have opened a realm of new possibilities in terms of i) how the convective and acoustic sources terms can be identified, ii) how the interaction between the source terms and the side glass can be described and finally iii) how the transfer path from the sources to the interior of the vehicle can be modelled. This work discusses several simulation methods that can be used to represent the physical phenomena involved such as CFD, FEM, BEM, FE/SEA Coupled and SEA. This work focuses on the validation of the wind noise source characterization method and the vibro-acoustic models on which the wind noise sources are applied in the framework of a benchmark proposed by Hyundai Motors Corporation.

• Bulletin of the Korean Chemical Society
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• 제23권12호
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• pp.1769-1772
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• 2002

Previous $^{19}F\;and\;^{1,2}H$ electron-nuclear double resonance (ENDOR) study of fluorometmyoglobin (MbF) in frozen-solution state provided sensitive tools sensing subtle structural changes of the heme that are not obtainable from X-ray. [Fann et al., J. Am. Chem. Soc. 1995, 117, 6019] Because of the intrinsic inhomogeneouse EPR line broadening effect of MbF in frozen-solution state, detection of the intrinsic inhomogeneouse EPR line broadening effect of MbF in frozen-solution state, detection of the electronic and geometrical changes of the heme ring itself and the proximal histidine by using $^{14}N$ CW ENDOR was interfered. In the present study, hyperfine-sensitive $^{14}N$ Mims ENDOR technique of pulsed-EPR was employed to probe the changes. With two different $\tau$ values of 128 and 196 ns, $^{14}N$ ENDOR signals of the heme and proximal histidine were completely resolved at $g'_{II}(=g_e=2)$. This study present that X-band $^{14}N$ Mims ENDOR sequence can sensitively detect the small changes of the spin densities and p orbital populations of the proximal and the heme nitrogens, caused by ligand and pH variation of the distal site.