• 한국표면공학회지
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• 제46권4호
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• pp.139-144
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• 2013

c-BN(cubic boron nitride) is known to have extremely high hardness next to diamond, as well as very high thermal and chemical stability. The c-BN in the form of film is useful for wear resistant coatings where the application of diamond film is restricted. However, there is less practical application because of difficult control of processing variables for synthesis of c-BN film as well as unclear mechanism on formation of c-BN. Therefore, in the present study, the structural characterization of c-BN thin film were investigated using $B_4C$ target in r.f. magnetron sputtering system as a function of processing variables. c-BN films were coated on Si(100) substrate using $B_4C$ (99.5% purity). The mixture of nitrogen and argon was used for carrier gas. The deposition processing conditions were changed with substrate bias voltage, substrate temperature and base pressure. Fourier transform infrared microscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were used to analyze crystal structures and chemical binding energy of the films. In the case of the BN film deposited at room temperature, c-BN was formed in the substrate bias voltage range of -400 V~ -600 V. Less c-BN fraction was observed as deposition temperature increased and more c-BN fraction was observed as base pressure increased.

• 상하수도학회지
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• 제21권1호
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• pp.113-122
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• 2007

Experimental studies were performed to investigate speciation and leaching potential of heavy metals(Cu, Cd, Pb Zn, Ni) in ten sediment samples collected from Nakdong River. Acid Volatile Sulfide (AVS) and Simultaneously Extractable Metals (SEM) measurements were used to estimate heavy metals that can be leached under anaerobic conditions. Sequential Extraction Procedure (SEP) and Toxicity Characteristic Leaching Procedure (TCLP) were used to characterize speciation and leaching potential of heavy metals under aerobic conditions. The results show that total concentrations of Cu, Zn and Ni were relatively high in the sediments from points Seongseo industrial complex stream (upper stream) (D), Seongseo industrial complex stream (midstream) (E), Dalseo stream (F), and Nakdong river estuary (J), and that Cd concentrations were higher in all sampling points except for Goriung Bridge (G) and Soosan Bridge (H). SEM and AVS analyses reveal that samples from points Ilsun Bridge (A), Namgumi Bridge (C), and Soosan Bridge (H) have potential of heavy metals leaching, although leachable concentrations are relatively low. The leaching potential of heavy metals in other points was low because of higher concentrations of AVS than SEM. SEP results show that more than 50% of Cu, Zn and Ni were present in residual fraction, which means these metals are less amenable to leaching in anaerobic conditions. On the other hand, more than 50% of Pb and Cd were extracted during the first through third step of the SEP, which means substantial fraction of these metals can be leached upon changing of redox conditions. TCLP tests predict that leaching potential of heavy metals was generally low, which is consistent with the results obtained by AVS and SEM measurements.

• 한국식품과학회지
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• 제11권2호
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• pp.122-125
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• 1979

배아를 제거한 현미(품종 : 아끼바레 및 밀양 23호)를 중량비로 약 $5{\sim}6{\;}%$씩 계속 5번 나누어 제거후 각 가루획분, 잔여 미립 및 현미의 칼슘, 인산, 철분, 비타민 $B_1$ 및 $B_2$를 정량하여 이들 성분의 분포를 살펴보았다. 처음 획분(현미를 $5{\sim}6%$ 도정한 가루)은 현미 자체보다 칼슘 및 인산이 8배, 철분이 4배, 비타민 $B_1$이 3배, 비타민 $B_2$가 4배 많았다. 이들 성분은 미립외부로부터 중심으로 갈수록 그 함량이 적었다. 인산 및 비타민 $B_1$의 분포양상은 두 품종간에 차이가 없었으나 밀양 23호는 아끼바레에 비하여 칼슘 및 비타민 $B_1$의 함량은 중심으로 갈수록 급격히 감소한 반면 철분은 오히려 균일하게 분포되어 있었다.

• Journal of Plant Biotechnology
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• 제47권1호
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• pp.90-99
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• 2020

This study aimed to screen for plants with antimicrobial potential among the evergreen woody species of South Korea that are used for horticulture and landscaping and to provide basic information about plants with proven antimicrobial activity to underpin future research. The plant materials were extracted under various conditions, and the antimicrobial activities of the extracts were evaluated by agar diffusion assay. The screening tests demonstrated that the crude extracts of 43 species had inhibitory effects against S. aureus. The inhibitory activities of four species (Elaeocarpus sylvestris, Camellia japonica, Cleyera japonica, and Quercus salicina) were relatively higher than that of the synthetic antimicrobial agents methylparaben and phenoxyethanol. The highest inhibitory activity was observed with the leaf extracts (extracted with methanol for 30 minutes) of E. sylvestris, based on induction of the largest inhibition zone of 23.3 mm in size. In addition, solvent fractions of E. sylvestris were evaluated. The largest inhibitory zone of 23.1 mm was observed for the n-butanol fraction, which is likely to contain effective compounds that exhibit inhibitory activity against S. aureus. In contrast, n-hexane and residual aqueous fractions showed no antimicrobial activity. Overall, our findings confirm that evergreen woody plants native to South Korea have potential antimicrobial activity.

• 대한환경공학회지
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• 제27권1호
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• pp.25-35
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• 2005

산업도시인 울산지역의 토양을 대상으로 단계별추출법을 통해 토양 내 축적된 중금속의 총 농도와 존재형태에 대해서 분석하였다. 울산지역을 오염배출원의 특성별로 6개(녹지, 주거지, 교통밀집, 기계 및 조선공단, 석유화학공단, 비철금속공단) 지역으로 구분하여 토양시료를 채취하였다. 연속추출법에 의하여 분석한 토양 중 중금속의 총 농도는 대체적으로 비철금속공단지역 >> 기계 및 조선공단지역 > 교통밀집지역 > 녹지 > 주거지의 순으로 나타났다. 거의 대부분의 지역에서 Cd, Cr 및 Ni은 50% 이상이 residual의 형태로 존재하였고 다음으로 Fe & Mn oxide 형태였다. 그러나 다른 지역보다 다소 높은 중금속 농도를 보였던 비철금속 공단지역에서는 residual의 존재비율이 낮았으며, 다른 지점에 비해 organic & sulfides의 비율이 높았다. Cu는 지역에 따라 다소 다른 존재형태를 보였다. Pb와 Zn은 Fe & Mn oxide가 가장 중요한 존재형태였고 Pb의 경우 그 다음으로 residual이 높은 존재형태를 보였다. 토양이나 빗물의 pH와 같은 환경 조건의 변화에 따라 쉽게 자연계로 유입될 수 있는 이동성을 가진 exchangeable 및 carbonates형태의 중금속이 차지하는 비율은 분석대상 전 지점에 걸쳐 대체적으로 낮은 것으로 나타났다. 그러나 비철금속 공단지역의 토양에서는 중금속의 총 농도가 심각하게 높게 나타났다. 그래서 토양 중 이동성 중금속의 상대적인 존재비율은 낮을지라도, 그 지역의 매우 높은 총 농도 때문에 많은 양의 중금속이 자연계에 유입될 가능성이 크다고 볼 수 있다. 따라서 배출원에서의 사전 오염방지 대책이나 중금속에 오염된 토양의 복원 등 긴급한 대책이 절실한 것으로 판단된다. 또한, 왕수추출법과 연속추출법에서 얻어진 중금속의 총 농도는 Cd를 제외하고 전 항목에 대해 높은 결정계수(0.7 < R2 < 0.9)를 보였다.

• 한국토양비료학회지
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• 제38권1호
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• pp.52-57
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• 2005

굴껍질을 주원료로 하는 패화석비료가 토양개량제로서 배추의 생육 및 수량을 증진시키고 토양의 이화학적 특성 개선에 효과가 있는 것으로 알려져 있다. 평택통 (Fine silty, Typic Endoaquepts)의 밭 토양에 굴패화석비료를 0, 4, 8, 12, and $16Mg\;ha^{-1}$ 처리하여 봄배추를 재배하는 과정 중 패화석비료 시용량이 증가함에 따라 토양내 유효인산함량은 일정하게 증가되는 것이 확인되었다. 유효인산 함량의 증가는 1차적으로 패화석비료내 포함된 인산 ($1.5g\;P_2O_5\;kg^{-1}$)의 직접투입이 토양 내 전 인산을 증가시키고 유효인산을 증진시킨 것으로 평가되었다. 그리고 알카리성 제재인 패화석비료가 pH 5.8의 공시토양의 pH를 중성범위로 높이면서 간접적으로 유효인산함량을 증진시킨 것으로 해석되었다. 패화석비료의 시용량이 증가함에 따라 토양내 수용성 인산과 Ca-P 함량을 다소 증가시켰으나, Al-P와 Fe-P의 비율을 크게 감소되었다. 결과적으로 패화석비료는 토양내 유효인산함량 증진에 효과가 있으며, 이렇게 많아진 유효인산을 이용하여 인산시비량을 저감하고 나아가 인산유출을 저감할 수 있는 방법이 될 수 있을 것으로 판단된다.

• Radiation Oncology Journal
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• 제6권2호
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• pp.211-226
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• 1988

방사선 단독 치료나 수술후 방사선 치료를 받았던 165명의 식도암 환자 중에서 평균 생존율은 6.6개원이였으며 3,5년 생존율은 $10\%,\;8\%$였다. 생존율을 semilogarithmical하게 나타낸 biphasic plotting에서 보면 non-responder group은 치료에도 불구하고 1년내 모두 사망하였고 responder group중에서는 수술후 방사선 치료를 받았던 환자 20명 $(54\%)$은 1, 2, 3년 생존율이 각각$80\%,\;70\%,\; 60%$였으며, 방사션 치료만 받은 환자 61명$(48\%)$의 생존율은 각각 $62\%,\;38\%,\;23\%$였다. 즉, 3년간의 생존율의 비교는 수술후 방사선 치료가 방사선 단독치료 보다는 좋았다 (P<0.01). 가장 많은 사망의 원인으로는 연하곤란$(55\%)$이였으며 환자의 대다수는 국소적인 치료실패에 의해 사망하였으며 $(62\%)$ 협착의 $88\%$는 지속적인 암의 존재와 관련이 있었다. 환자의 $50\%$는 국소적인 임파절 전이가 발견되었다. 수술전의 진단 실패율은 $54\%$가 국소임파절 전이 때문에, $29.7\%$가 육안적인 임파절 전이 때문에, $13.5\%$가 혈행성 전이 때문에 그리고 $14\%$가 국소적인 직접 침범 때문이였다. Conventional radiation (6000 cGy/30 fraction in 6 weeks)이나 hyperfractionation radiation (upto 6900cGy, l15cGy/fraction)이거나 관계없이 gross disease는 충분히 즉일수 없었다. 그러나 hyperfractionation 테크닉에 의해서 급성 방사선 염증이 감소되어서 환자의 고통을 덜어줄 수 있었으며 그 후의 만성 부작용으로서의 방사선 합병증이 현저히 감소되었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권2호
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• pp.907-923
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• 2020

For the severe haze situation in the Beijing-Tianjin-Hebei region, conventional fine particulate matter (PM2.5) concentration prediction methods based on pollutant data face problems such as incomplete data, which may lead to poor prediction performance. Therefore, this paper proposes a method of predicting the PM2.5 concentration based on image analysis technology that combines image data, which can reflect the original weather conditions, with currently popular machine learning methods. First, based on local parameter estimation, autoregressive (AR) model analysis and local estimation of the increase in image blur, we extract features from the weather images using an approach inspired by free energy and a no-reference robust metric model. Next, we compare the coefficient energy and contrast difference of each pixel in the AR model and then use the percentages to calculate the image sharpness to derive the overall mass fraction. Furthermore, the results are compared. The relationship between residual value and PM2.5 concentration is fitted by generalized Gauss distribution (GGD) model. Finally, nonlinear mapping is performed via the wavelet neural network (WNN) method to obtain the PM2.5 concentration. Experimental results obtained on real data show that the proposed method offers an improved prediction accuracy and lower root mean square error (RMSE).

• 한국세라믹학회지
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• 제29권7호
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• pp.558-564
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• 1992

The effect of composed phase in the hot pressed CaO-MgO-Al2O3-SiO2 glass-ceramic has been investigated through microstructure studies, thermal, physical and mechanical properties. Sintering was done in the condition at the temperature range 900~95$0^{\circ}C$ for 20~120 mins under 7.5 MPa unilateral pressure. Sintered ceramics were composed of diopside, anorthite, residual glass and the portion of each phase was dependent on the sintering temperature and the holding time: as the temperature increases, the amount of diopside increased and then the rate of increase of diopside reduced with increasing anorthite. The thermal expansion coefficient of hot pressed was reduced with increasing crystallinity of hot pressed and was in the range of 6.69~7.46$\times$10-6 K-1 below $600^{\circ}C$. The elastic constant of hot pressed increased with increasing crystallinity up to about 80%, but after that was reduced due to the change of microstructure. The flexural strength of sintered ceramics was decreased with higher temperature and holding time, while the fracture toughness of those increased. It was shown that the physical and mechanical properties of hot pressed ceramic were related to the fraction of composed sintered ceramics, similar to a particulate composite, to the crystallinity of 80% of the glass-ceramic.

• 환경영향평가
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• 제9권4호
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• pp.301-314
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• 2000

Marine surface sediments in the vicinity of Samcheonpo coal-fired power plant were analyzed by a total analysis($HF+HNO_3+HClO_4$) and sequential extraction procedure for heavy metals in order to investigate the total concentrations and geochemical phases of heavy metals. The result showed that the concentrations of Cr, Cu, Fe and Zn were within ranges typical for coastal areas, which reflected the mineralogical composition of the sediments in the studied area. However, the distributions of Cd, Co, Mn, Ni and Pb were rather different from the former, indicating that these heavy metals had a different origin, or that they were affected by a different geochemical mechanism. Chemical partitioning of heavy metals using sequential extraction procedure revealed that Cu, Fe, Pb, Zn were significantly bound to the residual phases of the sediments, whereas carbonate phases contained considerable amounts of Mn. The significant association of Pb with the exchangeable fraction also indicated that Pb was more mobile and bioavailable than Cu, Fe, Mn, Zn.