• 대한화학회지
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• 제32권2호
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• pp.113-121
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• 1988

역상 액체 크로마토그래피에 의한 방향족 슬폰산 및 카르복시산들의 머무름 기구와 분리를 브롬화 도데실트리메틸 암모늄(DTAB)을 포함하는 이동상에서 연구하였다. 머무름 기구는 DTAB가 정지상에 일차층을 형성하고 반면 음이온 시료와 이동상에 존재하는 다른 공존 음이온들이 경쟁적으로 이차층을 형성하는 이온-상호작용 모델임을 확인하였다. 시료들의 용량인자들은 pH, 여러 유기 용매들의 농도, 이동상에 존재하는 공존 음이온 및 시료의 작용기 등 여러 인자들에 의해 영향을 받았다. 그리고 몇 가지 유기 혼합시료들을 최적 조건하에서 상호 분리를 시도하였다

• Current Optics and Photonics
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• 제1권2호
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• pp.118-124
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• 2017

Color rendering index (CRI) and luminous efficacy (LE) are two key performance factors of white LEDs (WLED). While most recent works in optics focus on methodology to improve these factors, little attention has been dedicated to chemical composition of materials. This paper studies the effect of $Sr_{2.4}1F_{2.59}B_{20.03}O_{74.8}:Eu_{0.12},Sm_{0.048}$ phosphor (SrSm), in terms of concentration and particle size on CRI and LE of 8500 K - WLEDs. Importantly, the molar mass of the componential ions in SrSm are calculated to shed light on the connection between the chemical composition of the material of interest and the performance of WLEDs. Results show that CRI can be improved to a value of around 86 by boosting red-light components in WLEDs, for all 3 major configurations: conformal, in-cup, and remote phosphor. CRI value tends to decrease with larger size of particles, while LE value goes in the reverse direction. On the other hand, both CRI and LE appear to be reduced at higher concentration of SrSm. This light attenuation is analyzed by using the Lambert-Beer law and Mie-scattering theory.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3221-3224
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• 2010

This study investigates the requirements of lithium-air cathodes, which directly influence discharge capacity. The cathodes of Li-air cell are made by using five different carbon materials, such as Ketjen black EC600JD, Super P, Ketjen black EC300JD, Denka black, and Ensaco 250G. The Ketjen black EC600JD provides discharge capacity of 2600 mAh/g per carbon weight, while that of Ensaco 250G shows only 579 mAh/g. To figure out the differences of discharge capacity from carbon materials, their surface area and pore volume are analyzed. These are found out to be the critical factors in determining discharge capacity. Furthermore, carbon loading on Ni foam and amounts of electrolyte are significant factors that affect discharge capacity. In order to investigate catalyst effect, electrolytic manganese dioxide (EMD) is incorporated and delivered 4307 mAh/g per carbon weight. This infers that EMD facilitates to break $O_2$ interactions and leads to enhance discharge capacity.

• 대한화학회지
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• 제44권5호
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• pp.470-476
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• 2000

이 연구에서는 비화학전공 공학계 학생들의 일반화학실험에 대한 흥미도를 조사하고, 이러한 흥미도에 영향을 미치는 요인이 무엇인지 분석하였다. 연구결과 학생들은 일반화학 실험주제에 따라 흥미도의 차이를 보여주었다. 학생들은 이론에 치우치고 이를 재확인하 는 실험보다는, 실행활과 관련이 있고 자신들이 직접 무엇인가를 만들어 내는 실험을 선호하였다. 이러한 학생들의 흥미도에 영향을 미치는 변인으로 실험을 담당한 조교, 학생들이 전공, 성별의 요소를 선정하여 분석하였다. 이 중 조교변인이 학생들의 흥미도에 가장 큰 영향을 미치는 것으로 나타났으며, 학생들의 전공이나 성별은 학생들의 흥미도에 큰 영향을 미치는 않는 것으로 나타났다.

• Bulletin of the Korean Chemical Society
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• 제34권10호
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• pp.2978-2982
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• 2013

A doubly tethered $N-CH_3$ amide chiral stationary phase (CSP 4) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid was applied to the resolution of an antiarrythmic agent, tocainide, and its analogues and the chromatographic resolution results were compared with those on a singly tethered N-H amide CSP (CSP 1), a singly tethered $N-CH_3$ amide CSP (CSP 2) and a doubly tethered N-H amide CSP (CSP 3) under an identical aqueous mobile phase condition. CSP 4 was found to be generally better than other CSPs in terms of the separation factors (${\alpha}$) and resolutions (RS). The retention times of analytes denoted by the retention factors ($k_1$) on CSP 4 were quite long compared to those on other CSPs because of the improved lipophilicity of CSP 4. The long retention times of analytes on CSP 4 were successfully controlled by the addition of a small amount of ammonium acetate to aqueous mobile phase without hurting the chiral recognition efficiency. The variation of the content and type of organic and acidic modifier in aqueous mobile phase was found not to change the chiral recognition efficiency significantly.

• 한국환경과학회지
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• 제8권1호
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• pp.51-59
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• 1999

Chemical composition of atmospheric aerosols was measured at 4 sites in Pusan. All the samples were collected with a high volume air sampler from January to October 1996, to analyze major ions and heavy metals. Dominant ions of aerosols were S $O_4$$^{2-}$ in anion and N $a^{+}$ in cation. Sulfate, nitrate and ammonium ions in aerosols showed high enrichment factor to soil and seawater composition. The concentrations of heavy metals in aerosols was lowest at the site PI near the coast. The lowest concentrations of major ions and heavy metals mainly appeared in August, probably due to scavenging by frequent rains. Especially, the concentrations of total suspended particulate matter(TSP) and heavy metals in aerosols showed good correlations in Pusan. Based on crustal Al, enrichment factors for some metals(Zn, Cu, Pb, Cd) in aerosols were significantly greater than unity, and the order was Cd ＞ Pb ＞ Zn ＞ Cu. This evidence suggests that Cd and Pb are derived predominantly from non-crustal sources.s.

• Bulletin of the Korean Chemical Society
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• 제22권1호
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• pp.63-67
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• 2001

The photophysical properties and the singlet oxygen generation efficiency of tetrathiarubyrin have been investigated to elucidate the possibility of its use as a photodynamic therapy (PDT) photosensitizer by steady-state and time-resolved spectroscopic methods. The observed photophysical properties were affected by various molecular aspects, such as extended ${\pi}conjugation$, structural distortion, and internal heavy atom. The steady-state electronic absorption spectrum was red-shifted due to the extended $\pi-conjugation$, and the spin orbital coupling was enhanced by the structural distortion and the internal heavy atom effect. As a result of the enhanced spin orbital coupling, the triplet quantum yield increased to 0.90 $\pm$ 0.10 and the triplet state lifetime was shortened to 7.0 $\pm$ 1.2 ${\mu}s$. Since the triplet state decays at a relatively faster rate, the efficiency of the oxygen quenching of the triplet state decreases. The singlet oxygen quantum yield was estimated to be 0.52 $\pm$ 0.02, which is somewhat lower than expected. On the other hand, the efficiency of singlet oxygen generation during the oxygen quenching of triplet state, $f{\Delta}^T$, is near unity. Such high efficiency of singlet oxygen generation can be explained by the following two possible factors: The hydrogen bonding of ethanol which impedes the deactivation pathway of the charge transfer complex with oxygen to the ground state, the less probability of the aggregation formation.

• Bulletin of the Korean Chemical Society
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• 제18권10호
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• pp.1085-1089
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• 1997

A new HPLC chiral stationary phase (CSP 3) has been prepared by connecting N-phenyl N-propyl amide of (S)-naproxen to silica gel through the 6-methoxy-2-naphthyl group of (S)-naproxen. The new CSP has been applied in resolving a homologous series of N-(3,5-dinitrobenzoyl)-α-amino acid esters and a homologous series of N-(3,5-dinitrobenzoyl)-α-(4-alkylphenyl)alkylamines. The separation factors, α, for resolving a homologous series of N-(3,5-dinitrobenzoyl)-α-amino esters and a homologous series of N-(3,5-dinitrobenzoyl)-α-(4-alkylphenyl)alkylamines on the new CSP have been found to remain almost constant throughout the wide range of the length of the alkyl substituent of the analytes while those on the previously reported CSPs (CSP 1 and 2) which were prepared by connecting N-phenyl N-propyl amide of (S)-naproxen to silica gel through the N-propyl group increase or decrease continuously. These results are concluded to support the chiral recognition models which utilize the intercalation of the alkyl substituent of the racemic analytes between the adjacent strands of CSP 1 or 2 to rationalize the increasing or decreasing trends of separation factors.

• Animal cells and systems
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• 제5권2호
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• pp.117-126
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• 2001

Occurence, seasonal changes and vertical distribution of the silica-scaled chrysophytes in a small fish-free pond were studied using electron microscopy (EM) and light microscopy (LM) from October 1998 to July 1999. The phytoplankton community was characterized by Chrysophyta and Cryptophyta. Ten species of the silica-scaled chrysophytes of genera Mallomonas, Synura, Chrysosphaerella and Spiniferomonas were identified by EM, and the most abundant species were Mallomonas akrokomos and M. portae-ferreae. The maximum population density of M. akrokomos was observed in December and several peaks appeared periodically at about one to two month intervals, whereas M. portae-ferreae developed the maximum density in March. The diurnal vertical distribution of M. akrokomos exhibited clear downward migration at night and slightly upward migration in the morning. A complex interaction among physico-chemical and biological factors seemed to affect the vertical distribution of M. akrokomos. However, the seasonal changes of M. akrokomos did not show significant corre1ations with the physico-chemical and some biologica1 factors. Although M. akrokomos was evenly distributed throughout the water column during some experimental periods, the diurnal patterns found in the two diurnal cycles showed consistency in that it clearly avoided the surface water during the day. This suggested that M. akrokomos may be a shade plankton with maximum densities below surface layer.

• 교육시설 논문지
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• 제26권3호
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• pp.3-13
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• 2019

Purpose: The human body is a chemical laboratory. Artists are exposed to a variety of chemicals in art studio space and the art materials used in the creation contain toxic ingredients, exposing them to a variety of incurable diseases, including cancer. It aims to analyze the problems of the studio space environment and the risks of art materials, which are fundamental causes of the outbreak of incurable diseases, and to derive the direction of specific practices that can reduce the occurrence of incurable diseases by artists. Method: The harmfulness of an artist's creative space is the cause of a disease outbreak, and two primary factors cause it. One is the environmental hazards caused by the use of tools, air pollution, and chemical hazards caused by art materials in the architectural space environment of the studio. Necessary measures are put forward to control disease outbreaks by identifying the status and cause of intractable diseases caused by studies. Result: The plan is urgent for the establishment of safety rules and regular pre-trainthese two factors and analyzing the results of prior research and implementation investigationing, the legal provisions of studio architecture design and the introduction of labelling rules to control the distribution of harmful art materials.