• 한국환경농학회지
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• 제27권3호
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• pp.279-284
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• 2008

We investigated whether carboxylate exudation of Brassica pekinensis Rupr. was affected by nitrate deposition from simulated acid rain. A gas chromatographic (GC) analysis was employed for the determination of low molecular weight organic acids (LOA) in rhizosphere soils, bulk soil, roots and leaves of Brassica pekinensis Rupr.. Rhizosphere soils were collected after 8 weeks of plant growth by first removing the bulk soil from the root system and then by mechanical move off the rhizosphere soil that adhered to the root surface with soft brush. Soil and plant materials were simultaneously extracted with the mixture of methanol and sulfuric acid (100:7, v/v). Seven organic acids, oxalic, malonic, fumaric, succinic, maleic, L-malic and citric acid were identified and quantified by GC equipped with FID. Oxalic, L-malic, and citric acids were found in both the bulk and rhizosphere soils, while most LOAs were not detected in the control treatment. On the contrary, except maleic acid, all other organic acids were detected in the leaves and roots of cabbages treated with nitrate deposition.

• 공업화학
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• 제5권2호
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• pp.313-320
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• 1994

로진과 말레산무수물로부터 rosin-maleic anhydride adduct(RMA)를 합성하였다. 중합반응의 단량체로서 이용하기 위한 고순도의 RMA의 합성에는 정제공정을 수반하는 용융합성법과 정제공정이 불필요한 용액합성법을 이용하였다. 용액합성법에서 합성한 RMA의 수율이 용융합성업보다 높았다. 용융합성법의 최고수율은 40%였으나 사염화탄소 및 아세트산을 반응용제로하는 용액합성법에서 얻은 생성물의 수율과 순도를 검토한 결과 비교적 고순도의 RMA를 얻을 수 있었고, 수율은 사염화탄소 용제법의 경우 48%(이론수율 87.6%), 아세트산 용제법의 경우 51%(이론수율 94%)였다.

• Restorative Dentistry and Endodontics
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• 제21권1호
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• pp.136-149
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• 1996

The effects of various All-Etching Agents (10% phosphoric acid, 10% maleic acid and 10 % citric acid) and 32 % phosphoric acid and varied etching time were evaluated by observing the morphology of the etched enamel surfaces using Scanning electron microscopy and by measuring the shear bond strength of a composite resin to human enamel. A total of 156 extracted premolar and molar teeth free of irregularities were employed in this study. Specimens for the observation of enamel morphology were divided into 12 groups of 3 teeth each, based on the type of etchant used and application time. After exposure to the etching agent specimens were washed air-dried and then glued to aluminum stubs and coated with a layer of gold for examination in the scanning electron microscope. Specimens for the evaluation of bond strength were divided into 12 groups of 10 teeth each also based on the type of etchant used and application time. After exposure to the etching agent the specimens were washed, air-dried and a thin layer of bonding agent was applied using a brush. Z 100 composite resin was light cured to the surface and stored at $37^{\circ}C$, 100% humidity for 7 days. An Instron Universal Testing Machine was used to apply a shearing force at $90^{\circ}$ angle from the enamel surface. It is concluded from this study that commercial All-etching agents can be used with a 15-second etching without adversely affecting retention of dental resin materials. At the same time, the acid concentration is probably a suitable compromise regarding the acid's function as a dentin demineralizing all-etch conditioning agent. The following results were obtained. 1. Specimens etched with 10 % citric acid showed a random superficial etching pattern which could not be related to prism morphology. 2. Specimens etched with 10 % and 32 % phosphoric acid and 10 % maleic acid showed a type I pattern in which core material was preferentially removed leaving the prism peripheries relatively intact or a type II pattern in which prism peripheries were preferentially removed. This delineation became more distinguished as etching time was increased. 3. All-Etching Agents and 32 % phosphoric acid showed a statistically significant higher shear bond strength at 15 seconds etching time.(p<0.05) 4. 10 % maleic acid and 32 % phosphoric acid exhibited a statistically significant higher shear bond strength than 10 % phosphoric and citric acid at 15 seconds etching time.(p<0.05).

• Archives of Pharmacal Research
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• 제4권1호
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• pp.9-17
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• 1981

A simple, accurate and specific NMR procedure is described for the determination of amplicilin and cloxacillin mixtures in injection dosage form and capsules. The solvent was dimethysulfoxde $d_{6}$ and maleic acid was the internal standard. By integrating the peak at 2.68 ppm and 4.57 ppm, cloxacillin and ampicillin could be determined respectively. The relative proton ratio of ampicillin trihydrate and cloxacillin were 1.038 and 0.950. The coefficents of variation of amplicillin trihydrate and cloxacillin in a few commerical preparation were 1.55 % (n =9), 2.69 % (n =15).

• Journal of Photoscience
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• 제10권3호
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• pp.241-243
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• 2003

Photoreactions of some carbonyl compounds with TiO$_2$ were investigated in methanol. Although 1,3-cyclohexanedione and phthalimide afforded 3-methoxy-2-cyclohexen-l-one and 3-methoxy-1-isoindolinone, respectively, acid anhydrides such as succinic, phthalic, and maleic anhydrides gave the monoesters of dicarboxylic acids in good to excellent yields, when they were irradiated on TiO$_2$ in methanol with 300 nm UV light.

• 한국산학기술학회논문지
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• 제22권6호
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• pp.275-282
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• 2021

Maleic anhydride (MA)와 divinylbenzene (DVB)을 개시제인 di(tert-butyl-perxoyisopropyl)benzene (PK-14)과 함께 이축 압출기에서 용융 그래프팅 반응을 통해 상용화제인 high-molecular-weight maleic anhydride-grafted polylactic acids (HMMA-g-PLA)를 제조하였다. 제조된 HMMA-g-PLA의 특성을 분석하기 위해 Fourier transform infrared (FTIR), Melt index (MI), 그리고 역적정을 실시하였다. HMMA-g-PLA는 DVB의 함량이 증가함에 따라 MA의 그래프팅율은 증가하나 MI는 감소하였는데, DVB의 도입으로 PLA의 𝛽-scission 반응이 억제되어 분자량이 증가되었기 때문이다. HMMA-g-PLA를 사용한 PLA기반 합성목재(wood-plastic composites, WPCs)는 matrix인 PLA에 보강재인 목재와 무기 충전재인 talc를 첨가하여 일축 압출기로 용융 블렌드하였다. 상용화제인 HMMA-g-PLA가 도입된 WPCs는 도입되지 않은 WPCs와 비교하여 더 높은 굴곡강도 및 충격강도를 보였다. 이것은 Scanning electron microscope (SEM) 분석을 통해 HMMA-g-PLA의 첨가로 PLA와 목분과의 계면 결합력이 우수해졌기 때문인 것을 알 수 있었다. 하지만 HMMA-g-PLA의 함량이 높을 때는 WPCs의 기계적 물성을 악화시켰다. 이는 도입된 HMMA-g-PLA 상용화제의 분자량이 PLA 고분자 수지보다 더 낮아 기계적 물성을 감소시킨 것으로 판단하였다.

• 한국식품영양과학회지
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• 제20권3호
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• pp.220-224
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• 1991

물 및 다섯가지 탈검제(citric acid, phosphoric acid, acetic anhydride 및 maleic anhydride)를 사용하여 미강유를 탈검하고 그 탈검효율을 비교하였다. 미강유 원유로부터 인 함유 물질을 제거하는데 있어서 모든 탈검제가 보다 효과적이었으며, 특히 acetic anhydride와 phosphoric acid는 각각 92.5% 및 93.3%까지 인 함유율을 저하시켰다. 또한 비수화성 인지질 특히 Lyso PC를 제거하는데 있어서 모든 탈검제가 효과적이었다. 미강유로부터 추출한 AI의 인지질은 주로 PC, PI, PE 및 Lyso PC로 구성되어 있었으며, 주요 지방산은 oleic acid, linoleic acid 및 palmitic acid의 순이었다. Acetic anhydride를 사용하여 얻은 AI가 가장 안정된 유화를 형성하였으며, 반면에 phosphoric acid 및 oxalic acid를 처리하여 얻은 AI는 매우 빈약한 유화성을 나타냈다.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1991년도 제2차 학술발표초록집
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• pp.52-52
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• 1991

• Bulletin of the Korean Chemical Society
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• 제15권5호
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• pp.407-410
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• 1994

• 한국식품영양학회지
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• 제13권5호
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• pp.440-445
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• 2000

단감재배농가에서 전량 폐기되는 적과단감을 이용한 가공식품을 개발하기 위한 기초자료를 얻고자 일반성분, 유리당, 유기산, 무기질 및 비타민 등을 분석하였다. 일반성분은 수분이 89.08%로 대부분을 차지하였으며 회분이 0.26%, 조지방이 0.56%, 조단백질이 0.75%이었다. 유리당은 glucose와 fructose가 각각 3.34%, 3.01%로 대부분을 차지하였으며 sucrose는 미량 검출되었다. 유기산은 citric acid, maleic acid, fumalic acid, lactic acid 등이 검출되었으며 그 중 lactic acid가 68.65mg%로 전체 유기산 함량의 79%를 차지하였다. 무기질은 K, P, Na. Ca, Fe, Zn 등이 검출되었으며 그 중 K이 126.l2mg%로 대부분을 차지하였으며 Fe과 Zn은 미량 검출되었다. 비타민 A는 33.95 R.E.로 완숙단감보다 함량이 적었으며 비타민 C는 171.01mg%로 완숙단감에 비해 10배 이상 함유하였으며 비타민 B$_1$과 B$_2$는 소량 검출되었다.