• 한국진공학회:학술대회논문집
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• 한국진공학회 1994년도 제6회 학술발표회 논문개요집
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• pp.35-35
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• 1994

The surface segragation of NiZr, CuZr alloy has been studied wi th X-ray Imotoelectron spectroscopy(XPS), Auger electron spectroscopy(AES) and low energy ion scattering(LEIS). The composition of outmost atomic layer has been determinded by the use of LEIS at several incident energies using Ar+ ion. In the LEIS analysis, the effect of charge exchange has been estimated by a novel measurment of the charge exchange parameters while simul taneous determining the relative concentrations of Ni and Zr and the complementary information obtained will be described. The composition of the clean annealed surface, measured with AES only, will be contrasted wi th the surface concentration of the preferentially sputtered surface. The experimental results has been clearly demonstrated that when the NiZr ruld CuZr alloys are exposed to continuous Ar+ ion bombardment the outermost atomic layer is Zr rich due to preferential sputtering of Ni atoms. where Ni is preferentially sputtered, but the difference in sputtering yields is not sufficient to explain the observed composition. Therefore, it is necessary to consider other processes such as Radiation Induced Segregation(RIS). The surface composition of the heated sample surface predicts that Zr should surface segregate which futher supports the view that part of the Zr enrichment is due to RIS.to RIS.

• Food Science and Biotechnology
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• 제15권2호
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• pp.163-167
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• 2006

Pectin was enzymatically extracted from industrial lemon pomace by using an endo-polygalacturonase from Aspergillus niger as a processing aid and compared to pectin extraction by hot hydrochloric acid. The yield of pectin was 17.6 and 20.2% with enzymatic and acidic treatments, respectively. The molecular weight distribution did not vary greatly between the samples extracted with enzyme or acid. Large differences in charge density were observed, however, when the samples were analyzed by anionic-exchange chromatography. Pectin extracted by the enzymatic treatment indicated higher charge density than that obtained by hydrochloric acid. The higher charge density could due to the presence of endogenous lemon pectinesterase, which was activated at low pH 4.5 in situ conditions during the process of enzymatic extraction, leading to low methoxylated pectin with a higher charge density.

• 한국환경농학회지
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• 제3권2호
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• pp.50-54
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• 1984

K완효성 비료개발을 위해 $K^+$로 이온교환된 montmorillite를 규정하고 n-alkylammonium method에 의한 충전하 결정을 통해 그 특성을 확인하있다. 이 방법을 통해 결정내의 불균일한 전하분포를 식별하고 충전하 상하영역을 평가했다(충전하는 영일 bentonite에 국한 : ${\xi}=0.39-0.28e/(SiAl)_4O_{10}$, ${\xi}=0.34$). 그리고 층간 양이온 교환능(C.E.C.) 평균가는 0.915meq/100g임을 알았다.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.457-465
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• 2014

Size-controlled lead sulfide (PbS) quantum dots were synthesized by the typical hot injection method using oleic acid (OA) as the stabilizing agent. Subsequently, the ligand exchange reaction between OA and thioacetic acid (TAA) was employed to obtain TAA-capped PbS quantum dots (PbS-TAA QDs). The condensation reaction of the TAA ligands on the surfaces of the QDs enhanced the conductivity of the PbS-TAA QDs thin films by about 2-4 orders of magnitude, as compared with that of the PbS-OA QDs thin films. The electron transport mechanism of the PbS-TAA QDs thin films was investigated by current-voltage (I-V) measurements at different temperatures in the range of 293 K-473 K. We found that the charge transport was due to sequential tunneling of charge carriers via the QDs, resulting in the thermally activated hopping process of Arrhenius behavior.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1994년도 제6회 학술발표회 논문개요집
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• pp.50-50
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• 1994

Half-metallic Heusler alloys (NiMnSb, ppdMnSb, pptMnSb) have attracted much attention due to their unique electronic and magnetic structures. Sppin-ppolarized band structure calculation ppredicts metallic behavior for the majority sppin states and semiconductor behavior for the minority sppin states. We have studied the electronic structures of these half-metallic Heusler alloys by core-level pphotoemission sppectroscoppy of Mn 2pp and 3s XppS sppectra. We found large intensities of Mn 2pp satellites and 3s exchange spplitting comppared with other metal Mn-alloys. These satellite structure can be understood by applying Anderson imppurity model. This fact supports the calculated sppin pprojected ppartial density of states which suggests that the valence electrons be highly sppin ppolarized near Fermi level and that the electrons involved with charge-transfer be mainly minority sppin ones which have semiconducting band structure. The trend of charge transfer energies Δ from ligands (Sb 5pp) to Mn 3d, obtained from our model fitting, is consistent with that calculated from sppin pprojected ppartial density of state. Also the trend of d-d electron correlation energies U calculated from Mn Auger line L3 VV by Mg $K\alpha$ source is comppatible with that resulted from our model fitting. We fitted the Mn 3s curve in the same way as for insulating Mn comppounds by using the same pparameters calculated from Mn 2pp curve fitting exceppt for the Coulomb interaction energy Q between core hole and d-electrons. The 3s sppectra were analyzed by combing the charge transfer model and a simpple model taking into account the configuration mixing effect due to the intra-shell correlation. We found that the exchange interaction between 3s hole and 3d electrons is mainly respponsible for the satellite of Mn 3s sppectra. This is consistent with the neutron scattering data, which suggests local 3d magnetic moment. We find that the XppS analysis results of Mn 2pp and 3s satellite structures of half-metallic Heusler alloys are very similar to those of insulating transition metal comppounds.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2009년도 춘계학술발표회
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• pp.89-94
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• 2009

본 연구에서는 부산 북항 재개발의 개발 단계별 해수순환 특성을 살펴보고, 이와 동시에 북항으로 유입되는 4개의 하천의 유량을 갈수기, 평수기, 홍수기로 나누어 각 시기별 하천유량의 유입이 북항의 해수순환에 어떠한 영향을 미치는지를 수치모의하고자 하였다. 결과적으로 부산 북항을 중심으로 한 해수유동 수치모의 시 건설 전과 후에 하천유량이 증가할수록 신선대 방향으로의 Flux가 증가하고 이는 건설 전 후와 상관없이 유동방향이 변하지 않기 때문인 것으로 사료된다. 또한 건설 이전의 홍수시 하천 조건에서의 해수교환율은 60%, 건설 전 후의 해수교환율은 하천유량조건과 관계없이 거의 같은 간으로 해수교환율이 증가하였다.

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1635-1639
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• 2011

An efficient and novel positive charge-doping on the sidewalls of multi-walled carbon nanotubes has been achieved in the presence of tetrahydrofuran as a dopant and Lewis acidic ionic liquids, [bmim]$Sb_nF_{5n+1}$ (n ${\geq}$ 2; bmim = 1-butyl-3-methylimidazolium), as an activator, leaving air-stable derivatives having positively charged sidewalls and the counter anions, [MWCNT$^{y+}$][SbF$_6^-$]$_y$ (MWCNT = multi-walled carbon nanotube). The derivatization took place very fast in one-pot and under mild reaction conditions. The ionic structure enabled a tunable dissolution of the derivatives in various solvents through anion exchange.

• 설비공학논문집
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• 제15권6호
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• pp.461-470
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• 2003

The purpose of this study is to investigate the performance of a transcritical cycle for hot water heating using $CO_2$ as a working fluid. Some of the main parameters that affect the practical performance of the $CO_2$ system are discussed; the performance on the variation of refrigerant charge, changes in flow conditions of secondary fluids, and that with or without internal heat exchanger, The experimental results show that the optimum charge is approximately the same for various mass flow rates of the secondary fluid at gas cooler. The experimental results on the effect of secondary fluids are in general agreement with the experimental results of transcritical cycle in the open literature and show similar trend for conventional subcritical vapor compression cycles. The heat exchanger effectiveness increases with an increase of the heat exchange area of the internal heat exchanger regardless of the mass flow rate at the gas cooler.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.132-135
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• 2003

Solution chemistry, sorbate chemistry, and sorbent chemistry were widely investigated to find important factors that affect PAH sorption on mineral surfaces and to elucidate its microscopic mechanism. The solution chemistry, pH and ionic strength caused measurable change of HOC sorption reaction to minerals. The detectable change of Ka occurred at a pH region crossing the PZC (Point of Zero Charge) of each mineral. The PAH hydrophobicity, one of sorbate chemistry, was observed to have a strong correlation with PAM sorption to mineral. Mineral surface area was not found to be a predominant factor controlling PAH sorption. The mineral type might be more likely to play a crucial role in controlling the PAH sorption behavior. The CEC (Cation Exchange Capacity) of mineral, representing surface charge density, has meaningful correlation with regression slope of sorption coefficients (log $K_{d}$) versus aqueous activity coefficients (log Υ$_{w}$).).).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.386-388
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• 2001

The change of the electricity charge from cost base to price base due to the introduction of the electricity market competition causes consumer to choose a variety of charge schemes and a portion of loads to be affected by this change. Besides, it is required the index that consolidate the price volatility experienced on the power exchange with gaming and strategic bidding by suppliers to increase profits. Therefore, in order to find a mathematical model of the sensitively-responding-to-price loads, the price-sensitive load model is needed. And the development of state-of-the-art technologies affects the electricity price, so the diffusion of high-efficient end-uses and these price affect load patterns. This paper shows the analysis on learning curves algorithms which is used to investigate the correlation of the end-uses' price and load patterns.