• Membrane Journal
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• v.12 no.4
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• pp.216-225
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• 2002

Experimental study on the crossflow electro-microfi1tation of simulated oil emulsion waste water was carried out with polypropylene microfiltration membrane to evaluate the applicability of electrofiltration process in the treatment of oily waste water generated from many industries including nuclear field. The effects of electric field strength transmembrane pressure, crossflow velocity, and oil emulsion concentration on the permeate flux were investigated. In electro-microfiltration process using the external electric field, significant enhancement of permeate flux was achieved by diminishing membrane fouling and it was shown that considerable permeate flux can be maintained for long-term operation compared with conventional membrane filtration process without an electric field.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.05a
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• pp.201-204
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• 2009

미용 향장분야에서 많이 사용되고 있고, 소염작용, 진통효과, 면역증진작용, 강장작용이 있다고 알려진 저먼 카모마일, 라벤더, 샌달우드, 호호바 등의 혼합 아로마 오일을 NC/Nga 생쥐의 피부에 도포하여 생쥐의 피부조직내 염증세포와 mast cell 의 변화를 파악하여 아토피 피부염에 대한 효과를 검증하였다. 그 결과 아로마 혼합오일인 CLS 가 아토피 피부염의 주증상인 표피세포의 각질화와 mast cell의 감소에 영향을 주어 아토피 피부염에 효과가 있을 것으로 사료된다.

• Tribology and Lubricants
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• v.11 no.4
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• pp.1-12
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• 1995

여러 가지 필수적인 윤활유 성상과 함께 요즘 개발된 엔진에서 요구되는 중요한 특성 중 하나가 윤활유 내의 공기 혼입(aeration) 문제이다. 만일 윤활유 내에 공기가 일정 한도 이상 혼입되면 윤활유가 수행하는 일반 기능 중 하중을 분산시키는 압력 분산 작용과 윤활 작용 및 마찰열을 식혀 주는 냉각 작용이 제대로 되지 않아 엔진 수명과 내구성에 심각한 문제를 초래한다. 특히 현재 밸브 소음 저감 및 정비성 향상을 위해 대부분의 엔진에서 채용하고 있는 hydraulic valve lash adjuster(HLA)에 미치는 영향이 가장 심각하다. HLA는 그 작동 특성이 엔진 오일의 비 압축성을 이용하고 있기 때문에 만일 HLA 내부의 고압실에 공기가 오일에 섞여 들어간다변 밸브 시스템 강성이 떨어지게 되어 오히려 HLA 사용 목적에 반해 밸크 이상 거동에 의한 소음이 유발될 뿐만 아니라 심하면 밸브가 파단되는 심각한 현상이 초래되기도 한다. 상기한 바와 같이 aeration 현상은 경우에 따라 매우 심각한 문제를 유발하기도 하며 엔진이 고속 고출력화 하면서 그 특성은 더욱 관심사가 되어 왔다. 따라서 엔진 각 부분의 올바른 기능과 신뢰성 확보를 위해 aeration의 특징 발생 원인 및 대책을 살펴보고 특히 oil aeration이 HLA와 엔진 베어링에 미치는 영향에 대해 분석 고찰해 봄으로써 그 특성을 이해하고자 한다.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.113-114
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• 2016

본 논문에서는 오일 쿨러용 컴프레셔의 속도 맥동에 의한 영향을 분석하고 이를 저감하기 위한 알고리즘을 제안한다. 일반적으로 공작기계의 공작물 가공부위에서 발생하는 열 변형 오차를 줄이기 위해 오일 쿨러용 컴프레셔가 사용된다. 하지만 싱글 로터리 구조의 컴프레셔에서 발생하는 기계적인 진동은 배관의 피로파괴와 소음을 야기하므로 반드시 저감시켜야 한다. 따라서 본 논문에서는 싱글 로터리 컴프레셔의 운전 시 발생하는 속도 맥동의 영향을 최소화할 수 있는 실시간 보상기법을 제안한다. 제안된 기법은 특정 맥동 성분을 저감할 수 있는 비례공진제어기를 적용하여 속도 맥동의 주파수 성분을 검출하여 이를 최소화 하는 방향으로 보상신호를 주입하는 방식이다. 시뮬레이션과 실험을 통해 제안하는 기법의 효용성을 검증한다.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.969-979
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• 2012

In this study, the effects of cosurfactant on phase equilibrium and dynamic behavior were studied in systems containing nonylphenol ethoxylate (NP) surfactant solutions and nonpolar hydrocarbon oils. All the cosurfactants used during this study such as n-pentanol, n-octanol and n-decanol acted as a hydrophobic additive and the hydrophobic effect was found to increase with both increases in chain length and amount of addition of a cosurfactant. Dynamic behavior studies under hydrophilic conditions showed that the solubilization of hydrocarbon oil by NP micellar solution is controlled by an interface-controlled mechanism rather than a diffusion-controlled mechanism. Both spontaneous emulsification of water into oil phase and expansion of oil drop were observed under lipophilic conditions because of diffusion of surfactant and water into oil phase. Under conditions of a three phase region including a middle-phase microemulsion, both rapid solubilization and emulsification of oil into aqueous solutions were found mainly due to the existence of ultralow interfacial tension.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.162-177
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• 2001

The hydrolysis rates of seven kinds of polyol ester base oils 〔POEs〕 of different branch shape were investigated by using a simple apparatus under mild acidic condition. Seven polyol ester base oils were made of poly hydric alcohols of two-four valence, normal or branched fatty acids of different carbon number. p-Toluene sulfonic acid was used as acid catalyst to accelerate the rate of hydrolysis. Partial esters and fatty acid produced by sequential hydrolysis of POEs were identified and their concentrations were determined by calibrated-internal standard method using Gas Chromatography. The rate constants of each step in sequential hydrolysis were determined by the least square method from rate equation and the concentration of each component, were compared with one another. It was shown that the rate of hydrolysis of POEs was strongly affected by whether molecular structure of fatty acid was straight chain or branch chain and which position was branched. The hydrolysis stability for all the POEs can be reasonably explained by using a steric hindrance effect anticipated fi:om their molecular structures affecting as water molecule makes an attack on the carbonyl carbon of POEs.

• Journal of Convergence for Information Technology
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• v.9 no.3
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• pp.56-67
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• 2019

The aim of this study was to investigate the influence of rosemary oil inhalation on memory, attention and autonomic nervous system according to the concentration difference in the aged. The research design was non-equivalent control group non-synchronized design. Participants were 89 individuals aged 65 or older who live in the community. Participants inhaled almond carrier oil(control group), 10%(experimental group A) and 100%(experimental group B) rosemary oil. Memory, attention, and autonomic nervous system responses were measured. Data were analyzed by SPSS win 24.0. The differences of the group and time were analyzed through repeated measure ANOVA. There were no significant differences in immediate recall (F=.42, p =.656), delayed recall (F=.45, p=.639), recognition (F=1.45, p=.242), digit span-forward (F=1.53, p=.223), digit span-backward (F=.46, p=.636), activities of sympathetic nerve system (LF)(F=.19, p=.828), activities of parasympathetic nerve system (HF)(F=.37, p=.694), LH/HF(F=1.39, p=.256), systolic blood pressure (F=.37, p=.694), diastolic blood pressure (F=1.25, p=.291). The inhalation of 10% and 100% rosemary oil for five minutes showed no significant effects on memory, attention and automatic nervous system in the aged.

• Clean Technology
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• v.25 no.4
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• pp.275-282
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• 2019

In this study, the extraction of Conger myriaster oil by using supercritical carbon dioxide (SC-CO₂) and organic solvent was investigated. The extraction conditions conducted for SC-CO₂ varied for pressure (25, 30 MPa) and temperature (45, 55 ℃), while the SC-CO₂ flow rate was kept constant during the experiment (27 g min^-1) and hexane was used as a conventional organic solvent. The extraction yield indicated that the best extraction condition would be SC-CO₂ at 55 ℃ and 30 MPa, resulting in the highest yield of 37.73 ± 0.14%. The oils were characterized for their fatty acid (FAs) composition using gas chromatography, while it was revealed that the major FAs were mystric acid, palmitoleic acid, oleic acid, electroosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). The oxidation stability of the extracted C. myriaster oil was evaluated by measuring the acid value, peroxide value, and free fatty acid. The best oxidative stability was obtained from SC-CO₂ extracted oil at 30 MPa and 55 ℃. There was a significant difference in the color properties of the SC-CO₂ and hexane extracted oils, with the SC-CO₂ extracted oil showing better chromaticity than the oil extracted using hexane. Extracting oils from C. myriaster with SC-CO₂ could bring better economic benefits than using organic solvents. When supercritical carbon dioxide was used, there was no post-treatment process; thus, it was confirmed that this is a more environmentally friendly oil extraction method.

• Elastomers and Composites
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• v.47 no.1
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• pp.36-42
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• 2012

More than 3 wt% of polycyclic aromatics (PCAs) in process oil is known to cause skin cancer. The criterion of distinguishing between low PCA oil and high PCA oil is based on 3 wt% of PCA. High PCA oil is called as a carcinogen like distillate aromatic extract (DAE). Low PCA oil is considered as safety oils like treated distillate aromatic extract (TDAE), mild extract solvate (MES), and paraffinic oil. Four types of process oils such as DAE, TDAE, MES, and paraffinic oil purified by solvent extraction and separation skills from SBR vulcanizates were measured by FT-IR techniques. The effects of rubber chemicals such as N-1,3-dimethylbutyl-N'-phenyl-p-phenylnenediamine (HPPD), polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMDQ), paraffin wax as antidegradants, and processing aid like Structol 40MS on paraffinic oil from SBR vulcanizates were also studied. The type of low or high PCA was identified by the relative abundance of absorbance at the aromatic substitution patterns of 864, 810, and $754cm^{-1}$ and at the paraffinic or naphthenic pattern of $721cm^{-1}$.

• Journal of the Korea Institute of Military Science and Technology
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• v.1 no.1
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• pp.166-188
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• 1998

본 논문에서는 쿼터니온 궤환 개념이 기존의 오일러각 궤환 개념에 비해 추력벡터제어(Thrust Vector Control) 방식을 사용하는 전술 유도탄 자세제어에 보다 효과적으로 적용될 수 있음을 보인다. 오일러각 궤환 방식을 택한 기존의 자세제어기에서 오일러각 궤환 부분을 쿼터니온 궤환으로 적절히 바꾸어 주게 되면 자세명령 크기 변화에 따른 시간응답 특성의 변화를 줄일 수 있으며, 쿼터니온 궤환 방식을 택할 경우, 우주비행체 자세제어 분야에서 활발히 연구되고 있는 고유축(Eigen Axis) 회전에 의한 자세변환을 수행할 수 있는 자세제어기 설계가 가능하다. 고유축 회전은 최단경로에 의한 자세변환 개념이므로, 이러한 능력을 갖춘 자세제어기는 신속한 자세변환이 필요한 전술 유도탄의 초기비행에 매우 효과적으로 이용될 수 있다. 더욱이, 제어법칙에 공력모멘트를 보상하는 항을 추가하게 되면 변화가 심한 공력 모멘트가 유도탄의 회전운동에 미치는 영향을 줄일 수 있어 고유축 회전성능을 보다 개선시킬 수 있다. 우선, 오일러각 궤환보다 쿼터니온 궤환이 유리한 점을 논하고, 쿼터니온 궤환에 근거한 자세제어기의 설계 개념과 제안된 제어기에 의해 구성되는 폐루우프에 대한 안정성 문제를 다룬 후, 시뮬레이션을 통해 그 타당성을 검증한다.