Rheology of Decamethylceclopentasiloxane (cyclomethicone) W/O Emulsion System

Choi, Min-Hyung,Jeong, So-Ra,Nam, Sang-In,Shim, Sang-Eun,Chang, Yoon-Ho The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.12

A highly dispersed W/O emulsion of silicone oil (cyclomethicone)/water system was prepared with a nonionic surfactant. The surface and interfacial tension between the oil and water were characterized in terms of the droplet size distribution and viscosity change of the emulsion. When the dispersed phase concentration was relatively high, the viscosity of the emulsion was rapidly increased and the droplet size of the emulsion was decreased. The rheological behavior of the emulsion system showed non-Newtonian and shear thinning phenomena depending upon the content of the dispersed phase. The droplet size of the emulsion was decreased with increasing surfactant content and water concentration. The relative viscosity of the emulsion was better predicted with the Choi-Schowalter model than with the Taylor model. The value of the complex modulus increased with increasing surfactant concentration. The linear viscoelastic region was expanded with a dispersed phase concentration. According to the change in the viscosity, the behavior was classified into three distinct regions: [I] linear viscoelastic, [II] partially viscoelastic, and [III] viscous. The creep/recovery behaviors in each region were characterized.

압축성 코드에서 예조건화 코드로의 이진

한상훈(Sang-Hoon Han),김명호(Myeong-Ho Kim),최정열(Jeong-Yeol Choi) 한국항공우주학회 2007 韓國航空宇宙學會誌 Vol.35 No.3

이차원 범프 유동에 대한 다양한 예조건화 행렬의 수렴 특성을 살펴 Choi와 Merkle의 예조건화 행렬을 선택하여, 압축성 및 예조건화 Roe의 Riemann 해법의 수치 소산항을 수학적으로 비교하였다. 이 결과 코드의 구조는 동일하게 유지한 채, 고유치의 작은 수정만으로 압축성 해법을 예조건화 해법으로 이전할 수 있는 방법을 알 수 있었다. 아울러 점성 유동 영역에서의 안정성 및 정확성을 향상시키기 위하여 von Neumann 안정 조건 및 점성 자코비안을 고려하였으며, 개발된 코드는 표준 검증 문제에 적용하여 검증을 수행하였다. Comprehensive mathematical comparison of numerical dissipation vector was made for a compressible and the preconditioned version Roe's Riemann solvers. Choi and Merkle type preconditioning method was selected from the investigation of the convergence characteristics of the various preconditioning methods for the flows over a two-dimensional bump. The investigation suggests a way of migration from a compressible code to a preconditioning code with a minor changes in Eigenvalues while maintaining the same code structure. Von Neumann stability condition and viscous Jacobian were considered additionally to improve the stability and accuracy for the viscous flow analysis. The developed code was validated through the applications to the standard validation problems.

열공형과 비열공형 피질하 혈관성 치매에서 위험인자의 차이에 관한 비교 연구

배희준,정지향,유경호,나덕렬,김상윤,최경규,양동원,손의주,이상도,김재우,박경원,김응규,이재홍,박미영,한일우,함동석,최문성,하충건,최성혜,이애영,이병철,한설희 대한치매학회 2003 Dementia and Neurocognitive Disorders Vol.2 No.2

Backgrounds and Objectives: Vascular dementia is a group of dementing disoders arising from various stroke syndrome. Among these. subcortical ischemic vascular dementia (SIVD) is regarded as a relatively distinct clinical entity. However, MRI patterns of SIVD are not homogenous. In some patients, lacunes are dominant, and in others, subcortical white matter changes are. This study was designed to compare risk factor profiles between SIVD with and without multiple lacunes. Methods: We divided 47 subjects (22 males, mean age. 68 years) recruited from VADAPET (Multicenter Trial For Evaluation Of The Changes In the PET Images Of Subcortical Vascular Dementia Patient) study into two groups one with more than 5 lacunes in deep gray matter (lacune group) and the other with 5 or less(non-lacune group) Clinical characteristics and laboratory findings of two groups were compared. Results: Nineteen of 47 patients (40%) belonged to the lacune group. The lacune and non-lacune groups d d not differ in the following variables: age, hypertension, diabetes mellitus, hyperlipidemia heart disease, history of stroke or TIA, history of trauma or major surgery, family history of hypertension stroke, or dementia, age at diagnosis of dementia, body mass index, white blood cell count, ESR, CRP, fibrinogen, hemoglobin A1C, total cholesterol. LDL cholesterol creatinine, proteinuria, glucosuria, and microhematuria. However, male sex, smoking alcohol. hemoglobin, and HDL cholesterol were possibly associated more with lacune group SIVD than with non-lacune group (p<0 1) Multivariate analyses revealed that smoking, hemoglobin, and HDL cholesterol were independent predictors of SIVD with multiple lacunes Conclusion: Our study suggests that SIVD with multiple lacunes may be significantly different in smoking habits hemoglobin, and HDL cholesterol from SIVD without multiple lacunes.

혈액 투석 환자에서 중심정맥 협착에 대한 스텐트 삽입술 : Wallstent Placement

임대승,노상필,이유선,정승현,김보영,이정우,강정아,김정희,이민수,정준용,최시완,정진옥,성인환,이강욱,신영태 충남대학교 의과대학 의학연구소 2002 충남의대잡지 Vol.29 No.1

Stenosis of central vein is a common complication arising after percutaneous subclavian vein catheter insertion performed for temporary vascular access in chronic renal failure patients undergoing hemodialysis. There are several treatment methods for the condition like percutaneous angioplasty(PTA), stent insertion, and surgery, but recent trend is toward PTA and stents. Among the patients diagnosed with chronic renal failure from March 1993 to May 2002 and undergoing hemodialysis through AV fistula, the 14 Patients in whom central vein stenosis arose were selected for the study. A total of 28 percutaneous interventions(5 PTA and 23 stent placement) were performed, and restenosis rate and the time taken till the restenosis in de novo lesions and instant lesions were compared. All 28 cases were operated successfully. The 14 cases that received both anigioplasty and stent placement initially. (de novo lesion : 14 cases), Among the 10 cases with de novo lesion that followed up more than 1 year, 3 cases are currently undergoing hemodialysis without restenosis, and the remaining 7 cases have recurred stenosis with the mean time to restenosis of 10.9 months. In the 7 cases in whom stenosis recurred, 11 interventions were done(instent lesion: 11 cases). 4 of these were using only ballon angioplasty with 100% restenosis rate and the mean time of 3 months until restenosis. The remaining 7 cases were using both balloon angioplasty and stent placement, also with 100% restenosis rate but with the mean time of 12 months until restenosis, which was later than the group receiving only balloon angioplasty. In treating the patients with central vein stenosis, stent placement seems to be more advantageous over PTA in terms of restenosis rate and the mean duration of patency. In the case of instent lesion, inserting the stent for the second time after stenosis recurred lengthened the duration of patency compared to performing balloon angioplasty alone.

전국 10개 종합병원 중환자실 환자의 직장내 Vancomycin-resistant Enterococci(VRE) 보균율, 보균의 위험요인 및 유전적 다양성 조사

정희진,송준영,엄중식,김우주,최선주,최정현,이혁,정문현,이광미,신동현,손보라,최종성,우흥정,권정아,이경원,최강원,박승철 대한감염학회 2002 감염 Vol.34 No.5

FLexural Beam에 따른 초음파 물체부상 이송시스템의 진동특성

정상화,최석봉 朝鮮大學校 機械技術硏究所 2005 機械技術硏究 Vol.8 No.2

In the semiconductor and optical industry. a new transport system which can replace the conventional transport system is required. The transport systems are driven by the magnetic field and the conveyer belt. The magnetic field may damage semiconductor and the contact force of the conveyer belt may scratch the optical lens. The system driven by the ultra sonic ware can solve these problems. In this semiconductor and optical industry. the non-contact system is required for reducing the damages. The ultrasonic transportation is the solution of the problem. In this paper, the ultrasonic levitation system for levitation object are proposed. The 3D vibration profile of the beam is measured by Laser Scanning Vibrometer for verifying the vibration characteristic of the system and the amplitude of the beam and the levitation heights of object are measured for evaluating the performance.

리튬이 도핑된 막을 이용한 실리콘-실리콘 접합

정지원,주병권,최우범,정성재,이남양,최두진,오명환 경북대학교 센서기술연구소 1997 센서技術學術大會論文集 Vol.8 No.1

Silicon-to-silicon anodic bonding was accomplished using lithium doped interlayer. Lithium doped interlayers were deposited on silicon substrates by electron beam evaporation, which has a fast deposition rate compared with sputtering method. Silicon-to-silicon bonding occurs in the range of temperatures from 250℃ to 300℃ with the applied voltages from 70V_(DC) to 100V_(DC). The bonding strength obtained from tensile test was about 5MPa under the condition of 80V_(DC) in 300℃. The surface morphology of lithium doped interlayer was studied with the atomic force microscopy (AFM). Finally, secondary ion mass spectroscopy (SIMS) analysis was carried out in order to investigate the role of the lithium ions in bonding mechanism.

장기간의 생식 및 자연요법 식이 후에 발생한 Kwashiorkor 1례

최성식,정혜천,하태선 충북대학교 의과대학 충북대학교 의학연구소 2003 忠北醫大學術誌 Vol.13 No.1

Kwashiorkor는 주로 저개발국가에서 단백질과 칼로리 섭취가 극도로 결핍되고 부적절한 영양을 공급함으로써 나타나는 질환으로 영아 초기에서 5세 사이의 어린 영아에 주로 나타나는데 모유를 이유한 후 양질의 단백질과 칼로리가 심하게 부족한 이유식이나 음식을 장기간 섭취할 경우에 주로 나타나지만 식이에 대한 부적절한 지식으로 단백질을 제한함으로 질환이 발생하기도 한다. 저자들은 부모의 식이에 대한 부적절한 지식으로 장기간의 생식과 자연요법으로 단백질 섭취가 제한되어 kwashlorkor가 발생한 24개월된 남자환아를 1례 경험하였기에 문헌 고찰과 함께 보고하는 바이다. Kwashiorkor occurs most commonly in areas of famine, limited food supply, and low levels of education leading to inadequate knowledge of proper diet. It is associated with extreme poverty in developing countries. It is the name given to the syndrome of severe protein malnutrition. Kwashiorkor is an African term that refers to a child from early infancy to 5 years of age who is no longer being breastfed. Signs and symptoms associated with the syndrome result from a lack of nutritional protein coupled with an excess of carbohydrates. We report on 1 case of Kwashiorkor caused by raw food and naturopathic medicine and present brief review of literature. The child presented at 24 months of age with generalized edema.

BLDC 모터를 이용한 PV 양수 펌프 시스템

최성호,조정민,전기영,김성남,성낙규,김용주,한경희 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-

In this paper, we adapted BLDC motor to PV water pumping systems to maintain high efficiency in the wide speed area. Also to design confidence, we adapted the vector control that drive the maximum torque at each speed limit. We designed optimal gain value of current, speed and pressure PI controller. Inverter gate pulse used Space Vector PWM to reduce torque pulsation of BLDC motor. Finally it was improve general matters of high water storage tank method by direct water supply pumping method.

양측성 관상동정맥루 1예

최용원,오석규,이재훈,이상재,권경희,최은경,김남호,정진원 圓光大學校 醫科學硏究所 2002 圓光醫科學 Vol.17 No.1

저자들은 호흡곤란, 흉부불쾌감, 심계항진 등을 주소로 내원한 환자에서 경흉부 및 경식도 심초음파 검사상 주폐동맥에서 이완기에 전행하는 지속적인 혈류의 흐름을 관찰하고, 관상동맥 조영술을 통해 좌전하행지 중간부위와 우관상동맥 근위부에서 각각 기시하여 공통경로를 이루면서 주폐동맥으로 유입되는 양측성 관상동정맥루를 보이는 드문 1예를 경험하였기에 문헌 고찰과 함께 보고하는 바이다. A coronary arteriovenous fistula is infrequently encountered vascular communication between a coronary artery and a cardiac chamber, a great artery or the vena cava. It is the most common congenital anomaly that can affect coronary perfusion. Bilateral involvement of coronary fistula constitutes an uncommon subgroup of coronary arteriovenous fistulas. A 69 year-old female patient presented with chest discomfort, palpitation, and dyspnea. In the echocardiography, doppler color flow imaging visualized abnormal flow signals with mosaic appearance in the main pulmonary artery during diastolic phase. Coronary angiography revealed arteriovenous fistula arising from the left anterior descending artery and the right coronary artery. Both coronary arteriovenous fistulas drained into the main pulmonary artery. We report a case of bilateral coronary arteriovenous fistula that was confirmed by echocariography and coronary angiography.