반회분 공정에 의한 실리카 미립자의 생성

김희택,김기도 漢陽大學校 工學技術硏究所 1998 工學技術論文集 Vol.7 No.1

기존의 회분식 반응을 통한 실리카 미립자 생성의 한계성을 극복하기 위하여 반회분 공정을 이용하여 Ethyl Silicate(TEOS)의 가수분해 로부터 실리카 미립자를 제조 하였다. 그 결과 생성된 실리카 미립자는 반회분 공정에 의한 경우가 회분식 반응에 의한 것보다 단분산도, 입경, packing, 구형, 수율면 등에서 더 좋은 결과를 나타내었다. 특히, 수 미크론의 입자 크기를 갖는 단분산 실리카 미립자를 제조 하기에는 반회분 공정이 매우 효과적인 방법임을 알 수 있었다. Silica fine particles were produced from the hydrolysis of Si(OC2H5)4 by using semi-batch process in order to overcome difficulties for a production of fine particles by a batchwise reaction. The SiO2 fine particles obtained using semi-batch process were better than those using batch process in size distribution, packing, mean size, yield, and sphericity. Especially, it was found that semi-batch process was a successful method of controlling the size, i.e., a narrow distribution of a particle size which ranges to several microns.

3-Joint Planar Type 로봇 매니퓰레이터의 자기동조적응제어에 관한 연구

김규로,양희주,유용석,최명진,오택열 慶熙大學校 大學院 院友會 1996 高凰論集 Vol.17 No.-

This study has parallelogram trajectory tracking of Three Joint Planar type Robot Manipulator. The equation of motion for the three joint planar manipulator are obtained by substituting Lagrange's energy expression into Euler-Lagrange's equation and forming the appropriate derivative. Lagrangian method allows us to obtain the dynamics equations for very complicated systems in the simplest manner possible. SISO model is used for design of the controller. The design of controllers may be considered primary controller for manipulators to track the desired trajectory under ideal conditions and secondary controller to compensates for undesirable deviations of the motion from the trajectory caused by external and internal disturbances. The aim of this paper is to evaluate the efficiency by self-tunning adaptive control and considering a characteristic of control. Through the computer simulation, obtained the following results 1) selt-tunning adaptive control is superior to PD control, 2) During the learning period, the adaptive control algorithm is searching proper estimates and controller gains. After this period, the outputs of the joints start tracking closely the desired valued.

신경망을 이용한 ATM 망에서 트래픽 제어에 관한 연구

서동신,김희철,임방택,나상동 조선대학교 동력자원연구소 1996 動力資源硏究所誌 Vol.18 No.1

A traffic control using back-propagation neural networks propose for the ATM communications networks. This paper proposes adaptive call admission control using back-propagation algorithm in link capacity control. In this paper, back-propagation algorithm is trained to estimate call admission rate from traffic load and link capacity, and link capacity assignment is optimized by back-propagation algorithm method which used learning rate and moment term. Therefore, simulation results yield efficient ATM traffic control which use neural networks training between quality of service(QOS) and traffic parameter in the number of class 1, 2 and evaluate call loss rate 10exp(-6) using the Erlang-Bequation by trained back-propagation neural networks.

동적방법을 이용한 SBR 열분해의 속도론적 연구

오세천,김희택 漢陽大學校 工學技術硏究所 2001 工學技術論文集 Vol.10 No.-

동적방법을 이용하여 고분자물질의 열분해 반응에 대한 각 속도상수를 구할 수 있는 새로운 속도론적 해석법을 제안 하였다. 본 연구에서 제시한 방법의 타당성을 검증하기 위하여 가열속도 10∼50℃/min 범위내에서 상업용 SBR 시료에 대한 TGA 열분해 실험을 수행하였으며, 동적방법으로부터 얻어진 결과와 비교 하였다. 그 결과 실험 데이터와 잘 일치함을 알 수 있었으며 이로부터 본 연구에서 제시한 동적방법의 타당성을 확인할 수 있었다. A new method of kinetic analysis using a dynamic method which accounts for the thermal degradation of the polymer at any time, was proposed. The method was applied to predict the thermal degradation of SBR(styrene-butadiene rubber) by a conventional nonisothermal thermogravimetric technique at several heating rates between 10 and 50℃/min. To verify the effectiveness of the kinetic analysis method used in this work, the calculation results based on dynamic method were compared to those of TGA(thermogravimetric analysis) data. From this work, it was found that the dynamic method used in this work gave a reliable kinetic parameters of the thermal degradation of SBR.

반응매체로써 용융염을 사용한 연소가스로부터 NO의 제거에 관한 연구(Ⅱ)

배성렬,김희택 漢陽大學校 環境科學硏究所 1989 環境科學論文集 Vol.10 No.-

기포탑내에서 용융염(50mol% NH₄HSO₄, 50mol% NaHSO₄)과 V₂??계 촉매를 사용하여 온도범위 150∼180℃ O₂존재하에서 NH₃에 의한 NO의 환원반응에 대하여 조사하였다. NO의 환원속도는 NO의 농도에 대하여 1차 나타내었고 V₂??와 V₂??-NH₄Br-TiO₂-SiO₂촉매계에서1차 속도상수를 결정하였다. 또한 같은 온도범위내에서 용융염중의 NO에 대한 Henry 상수를 결정하였다. The kinetics of the reduction of NO by NH₃in the presence of O₂ in molten salts of 50mol% NH₄HSO₄and 50mol% NaHSO₄with V₂O as catalyst were investigated by chemical absorption method using a bubble column reactor at temperatures ranging from 150 to 180℃. The rate of the reduction of NO could be expressed as first-order with respect to the concentration of NO. The first-order reaction rate constants with V₂?? and V₂??-NH₄Br-TiO₂-SiO₂as catalyst were determined. The Henry's law constants of NO in the molten salts were determined in the same range of temperature.

공냉형 흡수식 냉난방기용 5성분계 작동매체의 물성 측정 및 분석

윤혁민,김희택 漢陽大學校 工學技術硏究所 2000 工學技術論文集 Vol.9 No.1

에너지 절약과 지구 환경문제에 대한 관심이 증가함에 따라서, CFCs와 HCFCs와 같은 냉매가 필요없는 흡수식 냉난방기가 최근 많은 관심을 얻고 있다. 공기냉각방식의 흡수식 냉난방기는 소형장치를 위해 개발되었으나, 용해도와 증기압 등의 높은 물리화학적 특성들을 요구한다. 본 연구의 주된 목적은 5성분 작동매체의 가능성을 평가하는 것이다. LiBr+LiNO3+LiCl+ZnBr2 시스템을 선택하였고, 실험을 동해서 최적의 몰비가 LiBr:LiNO3:LiCl:ZnBr2= 5:1:2:2.5로 선정되었다. 용해도는 68~76wt%에서 측정하였고, 증기압은 293.15K~324.15K에서 측정하였다. 실험 데이터는 Antoine-type 식으로 상관관계를 지었고, 용해도와 증기압의 측정 값들을 통해서 P-T-X 선도를 작성하였다. In accord with the increasing concern about the energy saving and the global environmental issues, the absorption chiller is currently being considered very attractive since they do not require refrigerants such as chlorofluorocarbons(CFCs) and hydrochloro-fluorocarbons(HCFCs). Air-cooled absorption chiller is being developed for small scale but this unit requires high physical and thermal properties such as solubilities, vapor pressure and so on. The main purpose of this study is evaluating the possibilities of 5 components working fluid. LiBr+LiNO3+LiCl+ZnBr2 system was selected and the optimum mole ratio was experimentally determined to be LiBr:LiNO3:LiCl:ZnBr2=5:1:2:2.5. The solubilities were measured at concentrations from 68~76wt% and the vapor pressures were measured at temperatures from 293.15 to 423.15K. The experimental data was correlated with an Antoine-type equation and P-T-X chart was constructed through the measurements of solubility and vapor pressure.

도시고형폐기물의 성분분석에 관한 연구

선정화,김희택,배성렬,강신춘 한양대학교 에너지·환경기술연구소 1994 에너지·環境技術論文集 Vol.1 No.-

도시지역에서 배출되는 일반폐기물에 대한 성분분석결과 밀도는 250∼300㎏/㎥, 수분함량은 중량비로 평균 51.83%, 가연성분 42.09%, 회분 6.08%로 각각 측정되었다. 한편, 저위발열량은 주거지역이 700∼1,700㎉/㎏, 상업지역이 2,000㎉/㎏이상으로 측정되어 상업지역이 주거 지역보다 발열량이 높은 폐기물이 배출됨을 알 수 있었는데 이는 수분함량이 높은 주개류의 배출이 상업지역이 주거지역보다 적으며 소비자 포장지로서 종이, 비닐, 플라스틱류 등의 사용이 많은데 기인하는 것으로 생각되어 진다. 한편, 분리수거, 유가품에 대한 자원 재활용, 연탄재 배출의 감소추세 등의 효과로 폐기물 중 불연성 함량은 줄어들고 반면 종이, 비닐, 플라스틱류 등의 가연성 폐기물의 함량은 크게 늘어 전체적으로 폐기물의 질이 향상되고 있음을 알 수 있다. The analysis results of components of municipal solid wastes are as follows : ① Density ranged from 250㎏/㎥ to 300㎏/㎥. ② Water content, combustible content and ash content measured 51.83%, 42.09%, 6.08% respectively. ③ Low calorific value was ranged from 700 to 1,700㎉/㎏ in residential area and measured 2,000㎉/㎏ in commercial one. Therefore, it was known that calorific value of wastes in residential area is smaller than that in commercial area. Also, the quality of wastes was improved by increase of combustible content which results from vitality of valuable recycling, reduction trend of briquette ash generation rate and increase of paper, plastic consumption as wrapping materials.

컴퓨터를 이용한 혈액학 교육시스템의 개발

이기형,손보라,윤희석,조원덕,김승택 충북대학교 의학연구소 2001 忠北醫大學術誌 Vol.11 No.1

연구목적 : 전통적인 의학교육 시스템은 최근 개발되고 있는 여러 가지 영상 진단법 등 시각적 자료를 전달하는데 한계가 있으며, 이러한 한계는 모든 분야에 걸쳐서 나타나지만 특히 혈액학이나 심장학 등 시각적인 자료가 진단에 필수적인 분양에서 두드러진다고 할 수 있다.본 연구는 혈액학 교육에 사용되던 기존의 강의실 교육에 시각적 자료가 첨부된 CD-ROM을 개발하여 혈액학 교육 시스템을 개선하기 위한 것이다. 대상 및 방법 : 기존의 혈액학 교육에 있어서 필수적으로 강의 되어오던 자료를 수집하여 체계적으로 정리하였다.강의 자료에 따라서 필요한 영상 자료를 충북대학교 병원에 입원한 혈액질환 환자들의 검사 자료로부터 수집하여 컴퓨터를 기반으로 한 의학영상 처리 및 분석시스템을 통하여 이미지 파일로 변형하였다.또한 입원 환자들 중 대표적인 증례들을 수집하여 실제 임상 진료와 유사한 형태의 증례를 통한 학습을 할 수 있도록 하였다. 결과: 본 CD-ROM은 혈액학 교육에 필요한 대부분의 영역을 포함한다 각 질환의 병태생리, 진단, 임상양상, 치료 및 예후 등 전통적으로 강의되어 오던 강의록에 이미지 파일로 변형된 영상 자료를 필요한 곳마다 링크시켰다.따라서 학습자는 특별한 장치 없이 텍스트 및 영상을 한 화면에서 볼 수 있어 전통적인 교육 시스템에 비하여 시,공간적인 장점을 갖는다 할 수 있다.또한 입원 환자들로부터 수집된 증례를 통하여 실제 임상 진료와 매우 유사한 경험을 하도록하여 교육효과를 증대시켰다. 결론: 혈액학 교육에 있어서 멀티미디어적 효과를 극대화시켜 질환의 병태생리 등 강의실 교육자료뿐 아니라 진단에 필수적인 시각적 자료를 손쉽게 접할 수 있는 CD-ROM의 개발로 전통적인 강의방법이 갖는 한계를 개선시킬 수 있을 것으로 기대된다. Purpose : The traditional medical education system has its limitations in effectiveness of conveying informations in multiple modalities used in diagnosis of patients with hematologic diseases.This study was performed to develop such a multimedia system using computer based CD-ROM, which includes visual assistant systems, several hematological case studies as well as the traditional text-wise education systems. Materials and Methods: The informations about hematologic diseases were compiled and organized.The main visual data was peripheral blood smears, bone marrow data, and several laboratory results accrued from patients admitted to Chungbuk National University Hospital.Each visual data were transformed through computer-based medical image processing and analyzing system and saved as to JPEG files.Case studies were also acquired from admitted patients and the laboratory data of that patients were used unmodified as possible as. Results : The CD-ROM covers almost all kinds of hematologic diseases that must be included in ordinary medical education courses.The text part includes pathophysiology, diagnosis, clinical features, treatment and prognosis of each hematologic diseases.The essential visual data were linked to each text part and accessible with ease, by one click.Case studies were simulated to actual clinical settings and presented step by step from diagnoses to treatments. Conclusion: A multimedia approach for the study of hematologic diseases has been developed and available in CO-ROM format.This system has advantage over traditional education system in conveying all kinds of visual data which is essential in educating hematologic disorders.

Formation of Monodisperse TiO2 Nanoparticles Generated without HPC Dispersant by Controlling Reaction Method and Temperature

Kim, Hee Taik,Kim, Ki Do 한국공업화학회 2000 Journal of Industrial and Engineering Chemistry Vol.6 No.5

Monodisperse TiO₂ nanoparticles were synthesized from tetraethyl orthotitanate (TEOT) dissolved in ethanol using a semibatch method, which is easier than a batch process in controlling the size, shape, and size distribution, without the addition of HPC. In this semibatch system, the preparation conditions of a low flow rate (1.1 ㏄/min) and high reaction temperature (70℃) were applied to produce monodisperse nanoparticles. As a result, the smallest size nanoparticles (∼12.7 ㎚ in diameter) with a narrow size distribution were produced. In addition, it was found that the semibatch reaction had an advantage of a short nucleation due to the repetitive addition of the TEOT solution and a high temperature, at which point the solubility of the solute increased, thereby decreasing the particle size. In conclusion, the efficacy of nanoparticle synthesis was established by controlling the reaction method and temperature

Neuroprotective Effect of Chebulagic Acid via Autophagy Induction in SH-SY5Y Cells

( Hee Ju Kim ),( Joon Ki Kim ),( Ki Sung Kang ),( Keun Taik Lee ),( Hyun Ok Yang ) 한국응용약물학회 2014 Biomolecules & Therapeutics(구 응용약물학회지) Vol.22 No.4

Autophagy is a series of catabolic process mediating the bulk degradation of intracellular proteins and organelles through formation of a double-membrane vesicle, known as an autophagosome, and fusing with lysosome. Autophagy plays an important role of death-survival decisions in neuronal cells, which may infl uence to several neurodegenerative disorders including Parkinson`s disease. Chebulagic acid, the major constituent of Terminalia chebula and Phyllanthus emblica, is a benzopyran tannin compound with various kinds of benefi cial effects. This study was performed to investigate the autophagy enhancing effect of chebulagic acid on human neuroblastoma SH-SY5Y cell lines. We determined the effect of chebulagic acid on expression levels of autophagosome marker proteins such as, DOR/TP53INP2, Golgi-associated ATPase Enhancer of 16 kDa (GATE 16) and Light chain 3 II (LC3 II), as well as those of its upstream pathway proteins, AMP-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR) and Beclin-1. All of those proteins were modulated by chebulagic acid treatment in a way of enhancing the autophagy. Additionally in our study, chebulagic acid also showed a protective effect against 1-methyl-4-phenylpyridinium (MPP+)-induced cytotoxicity which mimics the pathological symptom of Parkinson`s disease. This effect seems partially mediated by enhanced autophagy which increased the degradation of aggregated or misfolded proteins from cells. This study suggests that chebulagic acid is an attractive candidate as an autophagy-enhancing agent and therefore, it may provide a promising strategy to prevent or cure the diseases caused by accumulation of abnormal proteins including Parkinson`s disease.