• 펄프종이기술
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• 제40권4호
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• pp.59-65
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• 2008

Electrochemical properties of pulp fiber could be modified by LbL(Layer-by-Layer) multilayering. Salt concentration and pH affect the conformation and ionization degree of polyelectrolyte. In this study, therefore, we intended to evaluate the effect of pH and salt concentration in polyelectrolyte multilayering on the electrochemical properties of pulp fiber. The pH of the stock was varied to 4, 7, and 10. Salt concentration was controlled at 0.001, 0.003, and 0.005 M of NaCl. Higher zeta potential was obtained when pulp fibers were multilayered at the condition of higher pH and higher salt concentration. The final zeta potential of pulp fiber after multilayering was dependent on the adsorption ratio of polyelectrolyte and the initial zeta potential of fibers.

• 한국항해항만학회지
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• 제28권2호
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• pp.121-127
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• 2004

The shipping industry can be explained by a growing process of concentration and centralization of tonnage. A few largest shipping company control a great deal of shipping tonnage in the total tonnage through the process of concentration and centralization of tonnage in shipping over time. It confirms that a decreasing number of operators take an increasing quantity of tonnage in the total tonnage. Thus, the extremely dualistic structure (extremely unequal distribution of tonnage) are shown not only in the shipping industry in a given country but also in liner shipping in the world In this paper, the two countries, that is, Korea and Egypt, are compared considering the absolute size of tonnage and shipping policy in tenn., of concentration and centralization of tonnage in shipping. In order to measure the degree of concentration of tonnage in shipping, the quantitative measurements; the Lorenz curve and Gini coefficient are introduced. But it should be supplemented with the qualitative measures of tonnage in a given country.

• 펄프종이기술
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• 제36권5호
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• pp.78-84
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• 2004

Lignin precipitated from black liquor of soda pulping of bagasse was used to prepare cation-exchange resin. The effect of sulfuric acid treatment, concentration of phenol and formaldehyde on the properties of the prepared cation-exchange resin was investigated. It was found that sulfonated resinified phenolated lignin gave a resin with an ion-exchange capacity higher than that of resin, which resulted from sulfonation of resinified lignin at zero phenol concentration. Infrared spectroscopy of the prepared ion-exchange resin shows anew bands at 1060, 1160, 1280 and $1330\;cm^{-1}$ which indicated to the presence of $SO_{3}$.

• 인터넷정보학회논문지
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• 제12권4호
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• pp.51-59
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• 2011

본 연구의 목적은 해외유료방송의 시장집중과 시장성과 간의 실증적인 관계분석을 통해 국내 미디어산업의 바람직한 규제 및 정책 방향을 고찰해 보는 것이다. 세계적으로 방송통신이 융합되어 규제가 완화되고 있음에도 불구하고, 국내의 경우에는 미디어 시장이 특정사업자에 집중될 경우 시장 비효율이 발생하고 다양성이 훼손된다는 전제 하에, 여전히 시장집중현상을 집중적으로 규제하고 있다. 본 연구에서는 전 세계 17개 유료방송시장을 대상으로 1위 사업자의 시장점유 정도가 시장가격과 서비스 보급에 영향을 미치는지 분석하였다. 조사결과 시장집중 현상이 초래되어도 가격이 상향되거나 서비스 보급이 지연되는 않는 것으로 분석되었다. 본 연구결과, 시장성과에 영향을 주는 요인들이 다각화되었기 때문에 단순히 시장집중만을 규제하면 기술혁신 침체와 같은 부작용도 발생하는 것을 포함하여 다양한 시사점들이 도출되었다.

• 환경위생공학
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• 제11권3호
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• pp.1-7
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• 1996

Mandelic acid is the major metabolite and phenylglyoxylic acid is the minor metabolite of styrene in human. This study was conducted to investigate the correlation between exposure concentrations of styrene and concentration of the metabolites in urine The concentrations of metabolites in urine and exposure concentrations were measured in 60 workers who were occupationally exposed to styrene in FRP industry as well as paint industry and musical instrument manufacturing industry and the concentrations of metabolites in urine ware measured in 90 workers not occupationally exposed to styrene for review the background level in the unexposed population. The results obtained were as follows; 1. The mean exposure concentration is 16.6 $\pm $12.2 ppm (range 0.4-49.9ppm) in the styrene exposed workers. 2. The concentration of mandelic acid in urine collected at the end of shift from worker exposed 8 hours to 50ppm of styrene, based on extrapolation from correlation equations was 578.5 mg/g creatinine and 176.8 mg/g creatinine for next morning urine, the concentration of phenylglyoxylic acid in urine collected at the end of shift was 291.1 mg/g creatinine, 177.9 mg/g creatinine in next morning urine. In the sum of mandelic acid and phenylglyoxylic acid in the urine 870.2 mg/g creatinine in urine sampled at the end of shift corresponds to an exposure of 50ppm of styrene and 366.0 mg/g creatinine for next morning sample corresponds to 50ppm. 3. The correlation of the degree of exposed with sum concentration of mandeliacid and phenylglyoxylic acid in the urine was better(r=0.079 for end of shift, r=0.78 for next morning) than the correlation with single determinant measurement in urine(r=0.75 for mandelic acid at end of shift, r=0.73 for mandelic acid at next morning, r=0.69 for phenylglyoxylic acid at end of shift, r=0.62 for phenylglyoxylic acid at next morning). The monitoring of sum concentration of mandelic acid and phenylglyoxylic acid in urine is a valuable indicator of time weighted average daily exposure ti styrene. And the exposure standard of urinary metabolites produced by styrene should be set, in distinction urine at the end of shift from urine at next morning.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2012년도 제46차 학술발표회
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• pp.122-122
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• 2012

The aims of this study were to examine the efficacy of phytochemical compounds of colorants as anti-oxidant agent. The bioactive properties of natural colorants were studied by total phenolic contents, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and anti-bacterial activity in Escherichial coli. The concentration ($IC_{50}$) of various extracts from colorants required to exert 50% reducing effect on DPPH radical were found to be 0.007-4 mg/ml. Especially, the gallnut (Schlectendalia Chinensis) displayed remarkable effect of DPPH as compared to positive control ascorbic acid. The total phenolic contents (TPC) and restraint of E coli. also analyzed. It was found that gallnut extracts effectively inhibited DPPH radical at a concentration below 0.01 mg/ml. Natural colorant extracts could be of good resources as anti-oxidant and anti-bacterial agents. The results suggest that our study may contribute to the development of natural and functional materials with potential application to reduce oxidative damage.

• 한국언론정보학보
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• 제78권
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• pp.141-176
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• 2016

본고는 기존의 미디어산업 분석에서 사용된 정태적 집중지표가 일부 유형에 한정되어 있다는 것에 주목하고 새로운 정태적 집중지표의 활용 가능성을 탐색하였다. 특히, 산업 내의 불평등 구조를 포착하는 타일지수는 미디어 산업의 정태적 분석에 있어서 유용하게 사용될 수 있다. 동태적 경쟁을 포착하는 여러 유형의 이동지표도 미디어 산업을 동태적 시각에서 분석하는 데에 있어서 다양한 정보를 제공한다. 타일지수와 이동지표들을 활용하여 2001년에서 2015년까지 전국종합일간지 시장구조를 분석한 결과는 다음과 같다. 시장규모 변화 추세를 보면 매출액 규모는 감소했다. 반면에 자산 규모는 U자형의 추세를 보였는데, 이는 자기자본비율의 증가에 기인한다. 또한 발행부수 및 유료부수 규모도 감소했다(2010~2014년). 자산 기준으로 보면 시장집중도 뿐만 아니라 조중동 그룹과 기타 그룹 간 불균등도가 이명박 정부에서 가장 높았다. 매출액 기준으로 보면 시장집중도는 노무현 정부에서 가장 낮았으며 그룹 간 불균등도는 박근혜 정부 초기에서 가장 높았다. 전반적으로 신문사들의 자산과 매출액은 각각 평균으로 수렴하려는 이동성을 보였다. 그리고 자산에 비해 매출액으로, 매출액에 비해 발행부수로 시장점유율을 측정할 경우에 동태적 경쟁의 정도는 약하게 나타났다.

• Asian Journal of Atmospheric Environment
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• 제2권2호
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• pp.81-89
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• 2008

The numerical simulation of wind and ozone ($O_3$) transport in mountainous regions was performed with a computational fluid dynamics technique. A dry deposition model for $O_3$ was designed to estimate $O_3$ deposition in complex terrain, and the qualitative validity of the predicted $O_3$ concentration field was confirmed by comparison with observed data collected with passive samplers. The simulation revealed that wind velocity increases around ridge lines and peaks of mountains. The areas with strong wind corresponded well with the sites of tree decline at high altitudes, suggesting that it is an important factor in the localization of tree/forest decline. On the other hand, there is no direct relationship between forest decline and $O_3$ concentration. The $O_3$ concentration, however, tends to increase as wind velocity becomes higher, thus the $O_3$ concentration itself may be a potential secondary factor in the localized decline phenomena. While the diffusion flux of $O_3$ is not related to localized tree decline, the pattern of advection flux is related to those of high wind velocity and localized tree decline. These results suggest that strong wind with large advection flux of $O_3$ may play a key role in the promotion of tree/forest decline at high mountain ridges and peaks.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2003년도 한국해안해양공학발표논문집
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• pp.18-27
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• 2003

The goal of the UN Framework Convention on Climate Change (UNFCCC) is to stabilize atmospheric CO2 concentration for preventing global warming in future. However, there are many unknown factors regarding stabilization of CO2 concentration. What level of concentration should be appropriate to prevent global warming？ When should we stop the increase of CO2 concentration\ulcorner What kind of countermeasures of reducing CO2 emission will be available for CO2 stabilization？(omitted)

• 펄프종이기술
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• 제48권3호
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• pp.37-43
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• 2016

Various mechanical and chemical pretreatment methods including alkali treatment, pre-beating, enzyme treatment and oxidation treatment have been used to reduce the production energy of the microfibrillated cellulose (MFC). Among them, alkali swelling can be helpful to reduce the energy consumption because the internal bonding between fibrils could be weakened. In this study, dimethyl sulfoxide (DMSO) was used as a cosolvent to improve alkali pretreatment efficiency and the effects of NaOH concentration during NaOH-DMSO swelling on changes in fiber characteristics of softwood bleached kraft pulp (SwBKP) were elucidated. For alkali treatment in H2O-DMSO solvents, fiber length were decreased with increasing NaOH concentration while fiber width, curl and WRV were increased. WRV began to increase at 8% NaOH solution. In addition, above 8% concentration of NaOH, crystalline structure of pulp fibers converted from cellulose II to cellulose III by DMSO cosolvent. Comparing the previous results with this study, it was shown that DMSO cosolvent could promote swelling of pulp fibers and thus reduce NaOH concentration for the maximum swelling of fibers.