• 한국재료학회지
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• 제19권10호
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• pp.533-537
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• 2009

This paper presents a new method for the improvement of color temperature without the change of the driving scheme using transparent dielectric layers with various metal oxides (CeO$_2$, Co$_3$O$_4$, CuO, Fe$_2$O$_3$, MnO$_2$, NiO) in plasma display panels (PDP). In this study, we fabricated ZnO-B$_2$O$_3$-SiO$_2$-Al$_2$O$_3$ glasse with various metal oxides and examined the optical properties of these glasses. As the metal oxides were added to the glasses, the visible transmittances of the dielectric layers decreased and the transmittances in special wavelength regions were reduced at different rates. The change of the transmittance in each wavelength range induced the variation of the visible emission spectra and the change of the color temperature in the PDP. The addition of Co$_3$O$_4$ and CuO slightly decreased the intensity of the blue light, but the intensities of the green and the red light were significantly decreased. Therefore, the color temperature can be improved from 6087K to 7378K and 7057K, respectively.

• 상하수도학회지
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• 제33권6호
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• pp.457-467
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• 2019

Because non-point source pollution is very closely related to hydrological characteristics, its importance is highly emphasized nowadays along with accelerating climate change. Especially for Korea, the non-point source pollution and its control are entirely depending on runoff, precipitation, drainage, land use or development, based on geographical and topographical reasons of Korea. Many studies reported the physical (e.g., apparatus- and natural-type facilities, etc.) and chemical methods (e.g., organic and inorganic coagulants, etc.) of controling non-point pollutant source pollution, however, those are needed to be reconsidered along with climate change causing the unexpected patterns and amounts of precipitation and strengthen complexity of social community. The objectives of this study are to assess recent situations of non-point source pollution in Korea and its control means and to introduce possible effective ways of non-point source pollution against climate change in near future.

• 생약학회지
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• 제43권1호
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• pp.46-53
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• 2012

This study was conducted to investigate the change of antioxidant activity and ingredient in 4 species medicinal plant by processing. As a result, EtOAc extract and n-BuOH extract obtained from Cistanche deserticola Y. C. Ma and processed Cistanche deserticola Y. C. Ma showed difference on the experiment of antioxidant activity by DPPH method. Change of ingredient also was confirmed by TLC and HPLC analyses. Two main compounds of antioxidant activity change were isolated by column chromatography from the EtOAc extract and n-BuOH extract of Cistanche deserticola Y. C. Ma. The chemical structure of the compound 1 isolated from EtOAc extract of Cistanche deserticola Y. C. Ma was elucidated as 2'-acetylacteoside by means of IR and NMR analyses. Also, the chemical structure of the compound 2 isolated from n-BuOH extract of Cistanche deserticola Y. C. Ma was confirmed as acteoside. The antioxidant activity of processed Cistanche deserticola Y. C. Ma. was declined by 3 time decrements of 2'-acetylacteoside such as 1.89 mg/g to 0.62 mg/g and 2 time decrements of acteoside such as 5.81 mg/g to 2.67 mg/g by processing.

• Korean Chemical Engineering Research
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• 제56권1호
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• pp.139-142
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• 2018

Silicon (Si) is a promising anode material for next-generation lithium ion batteries (LIBs) because of its high capacity of 4,200 mAh/g ($Li_{4.4}Si$ phase). However, the large volume expansion of Si during lithiation leads to electrical failure of electrode and rapid capacity decrease. Generally, a binder is homogeneously mixed with active materials to maintain electrical contact, so that Si needs a particular binding system due to its large volume expansion. Polyvinyl alcohol (PVA) is known to form a hydrogen bond with partially hydrolyzed silicon oxide layer on Si nanoparticles. However, the decrease of its cohesiveness followed by the repeated volume change of Si still remains unsolved. To overcome this problem, we have introduced the electrospinning method to weave active materials in a stable nanofibrous PVA structure, where stresses from the large volume change of Si can be contained. We have confirmed that the capacity retention of Si-based LIBs using electrospun PVA matrix is higher compared to the conservative method (only dissolving in the slurry); the $25^{th}$ cycle capacity retention ratio based on the $2^{nd}$ cycle was 37% for the electrode with electrospun PVA matrix, compared to 27% and 8% for the electrodes with PVdF and PVA binders.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.683-686
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• 1998

In this paper, we carried out the fundamental experiments on the resistance of chemical attack of mortar using the electric are furnace slag as fine aggregate. The mortar specimens made from the EAF slag as fine aggregate were immersed in four sorts of chemical solutions, and measured to investigate the change of compressive strength and weight. As the results of this study, it was found that compressive strength and weight were increased with incresing replacement ratio of the EAF slag.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.221-224
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• 2002

Recently, simulation of Chemical Mechanical Polis hing is becoming more important because Process parameters on the material removal rate are complicated. And pattern-depent effects are a key concern in CMP processes. In this paper, we have been studied the changes of pattern density vs. oxide thickness with Stine's simulation model. We also have estimated the effective density using optimal window size with density mask, and have made a study of the change of oxide thickness as a function of polishing time.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.303-306
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• 1997

In this paper, we carried out the fundamental experiments on the resistance of chemical attack of mortar using the electric arc furnace slag as fine aggregate. The mortar specimens made from the electric arc furnace slag (EAF slag) as fine aggregate were immersed in artificial seawater and two sorts of chemical solutions, and measured to investigate the change of compressive strength and weight.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.183-188
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• 1996

The durability of concrete structures decrease due to deterioration of concrete when they are constructed in marine or pollutional environments. In this study, the mortar specimens made from the five different types of cement were immersed in artificial seawater and four kinds chemical solution, and were measured the change of compressive strength and weight. The results show that the longer the immersed days are, the more the compressive strength reduction is. It has been remarked that the resistance of slag cement and ground granulated blast-furnace slag is excellent in chemical attack.

• 대한화학회지
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• 제11권1호
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• pp.17-21
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• 1967

For utilization of Bunker-C residual oil produced at KOCO., the auther tested the properties of vacuum fraction and blown asphalt, and as the result of it, (1) Vacuum fraction had so broad range of viscosity and high flash point that could be produced all kind of lublicating oil, but had to be dewaxed for high pour point, (2) Urea dewaxing was suitable to lighter fraction but not to heavier fraction, so, for heavier fraction, solvent dewaxing was needed. (3) Blown asphalt produced from vacuum residue had uniform relation between softening point and penetration in spite of broad change of blowing condition and adding of catalyst.

• Korean Chemical Engineering Research
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• 제55권6호
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• pp.807-815
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• 2017

본 연구에서는 회전증발에서 건조 온도에 따른 파클리탁셀의 잔류 펜탄 제거 효율에 대해 조사하였으며 건조 공정에 대한 동역학 및 열역학적 해석을 수행하였다. 모든 온도(25, 30, 35, 40, $45^{\circ}C$)에서 건조 초기에 많은 양의 잔류용매가 제거되었으며 건조 온도가 증가할수록 건조 효율은 증가하였다. 동역학적 해석을 위해 실험데이터 값을 다섯 종류의 건조 모델식(Newton, Page, Modified Page, Henderson and Pabis, Geometric)에 적용하였으며, 이 중 Henderson and Pabis 모델이 큰 결정계수 값과 작은 평균평방근편차 RMSD 값을 가져 가장 적합함을 확인하였다. 또한 열역학적 해석을 수행한 결과, 회전증발에서의 활성화 에너지 $E_a$는 4.9815 kJ/mol이었으며, 표준 Gibbs 자유에너지 변화(${\Delta}G^0$)는 음수 값인 반면 표준 엔탈피 변화(${\Delta}H^0$)와 표준 엔트로피 변화(${\Delta}S^0$)는 양수 값을 나타내어 건조 공정이 자발적 흡열반응이며 비가역적으로 수행됨을 알 수 있었다.