타이타늄 임플란트와 상부구조물의 갈바닉 쌍의 전기화학적 특성

오근택,김명화,최병갑,김경남 大韓齒科器材學會 2003 대한치과재료학회지 Vol.30 No.1

For the aesthetic and functional restoration of edentulous patients, recently dental implants have been used widely. Dental implants and restorative alloys are required with the high corrosion resistance. Suprastructure and implant with different compositions, which are in electrical contact, may develop galvanic or coupled corrosion problems. Besides galvanic corrosion, crevice and pitting corrosion may occur in the marginal gap or the gap between dental implant assemblies. In this study, Ti implants, gold, silver-palladium, cobalt-chromium and nickel-chromium suprastructures were used to investigate their galvanic and crevice corrosion of suprastructure/Ti implant couples. Potentiodynamic and potentiostaic testing were performed in artificial saliva at 37℃. Potentiodynamic testing was carried out at the potential scan rate of 1 ㎷/sec and in the range of -600∼1600 ㎷(SCE). Potentiostatic testing such as open circuit potential and current densities at -250, 0 and 250 ㎷(SCE) was performed for 5000 seconds in artificial saliva. After electrochemical testing, the surface and cross-sectional morphologies of the samples were observed using optical microscopy. Potentiodynamic test results indicated that suprastructure/Tim implant couples exhibited the passive current density range of 0.5∼12 ㎂/㎠, Ti abutment/Tim implant and gold/Tim implant couples exhibited relatively low passive current density, Co-Cr/Tim implant couples the highest. Co-Cr and Ni-Cr/Tim implant couples showed the breakdown potentials of 700 and 570 ㎷(SCE), respectively. Open circuit potentials of silver, Ti abutment, gold, Ni-Cr and Co-Cr/Ti implant couples were -93.2±93.9, -123.7±58.8, -140.0±80.6, -223.5±35.1, and -312.7±29.8, respectively and stable according to immersion time. The couples exhibited cathodic current densities at -250 ㎷(SCE), especially, gold and silver alloys showed the high cathodic current densities of ±3.18 and ±6.63 ㎂/㎠, respectively. At 250 ㎷(SCE), Ti abutment/Ti implant couples exhibited the lowest current density of 9.48×10^-2 ㎂/㎠, and gold, Ni-Cr, Co-Cr and silver/Ti implant couples exhibited 0.313, 1.27, 5.60 and 8.06 ㎂/㎠, respectively. The couples exhibited relatively low current densities at 0 ㎷(SCE). The photographs after electrochemical testing showed crevice or pitting corrosion in the marginal gap and suprastructure surface. Although Co-Cr/Ti implant couples among the tested samples had the possibility of the galvanic corrosion, its degree was not significant.

광주지역 HIV/AIDS, 매독 혈청 양성률 및 임질 양성률 분포조사(2002-2006)

기혜영,최병선,서진종,김선희,김민지,김은선,박종태,정재근 대한감염학회 2009 감염과 화학요법 Vol.41 No.4

Background : The epidemic of human immunodeficiency virus (HIV) or sexually transmitted infections (STIs) is an important public health issue in the worldwide. Therefore, we investigated the trends of the seroprevalence of HIV and, syphilis and the gonorrhea positive rates in Gwangju from 2002 to 2006. Materials and Methods : The results of laboratory tests for HIV, syphilis and gonorrhea were collected from five public health centers and 19 hospitals in Gwangju. The number of tested patients from 2002 to 2006 was 348,202 cases for HIV, 80,115 cases for syphilis and, 103,548 cases for gonorrhea. Results : HIV/AIDS infections have rapidly increased at public health centers and hospitals. Especially, most of newly HIV-infected people were patients on ambulatory care/hospitalization, and they were also found via preoperation tests and according to the clinical symptoms. The gonorrhea positive rates have gradually decreased by year while the syphilis infection rates have slightly increased from 2002 to 2006. Conclusions : We have to determine the reasons why HIV and syphilis infections, but not gonorrhea, have increases simultaneously by the year. These results should be helpful to create a more effective STD prevention policy and the treatment guidelines for the people in Gwangju in the near future.

국내 Human Immunodeficiency Virus(HIV) 감염자와 정상인의 면역학적 표지인자 비교연구

신영오,류재천,최병선,박용근 THE KOREAN SOCIETY FOR BIOMEDICAL LABORATORY SCINE 1995 Journal of biomedical laboratory sciences Vol.1 No.1

HIV감염자는 질병의 진전에 무관하게 감염 후의 경과시기에 따라서 CD4 T림프세포등 각종 면역상태를 나타내는 표지가 변한다. 따라서 HIV감염자의 질병진전을 예보하기 위하여서는 정기적으로 CD4등 각종표지를 측정하여 감염자의 질병상태를 monitoring하게 된다. 그러나 이러한 수치를 감염자관리에 적용하기 위하여서는 우리나라 일반인의 정상치를 파악하여 이를 지표로 해야하므로 국내정상인의 각종면역치에 대한 조사가 요구된다. 현재의 기준으로는 500이하로 떨어질 때에는 예방차원에서 AZT를 복용하게 되며 200이하로 떨어지면 질병의 유무에 관계없이 환자로 관리하게 된다. 본연구에서는 한국인 185명의 감염자와 140명의 비감염자에 대하여 정기적으로 CD4 및 CD8T 림프세포와 CD4/CD8비를 측정하였다. 시험은 Flow cytometer(Facstar)를 이용하여 각각의 CD 분자에 대한 모노크로날 항체를 이용하여 2중혈광색소염색방법으로 측정하였다. HIV감염자의 CD4-T림프세로 절대수 및 백분율은 각각 462 및 18.2%이었는 반면, CD8의 수치는 1,170 및 47.0%이었다. 또한 CD4/CD8비는 0.43이었다. 이와는 대조적으로 비감염자의 경우, 한국인의 CD4의 평균세포수는 886, 백분율은 32.9%이었으며, CD8 세포수는 730, 백분율은 26.8 그리고 CD4/CD8비는 1.31이었다. 외국인과 한국인과의 면역지표수치를 비교하였을 때에 CD4세포수와 백분율, CD8의 백분율에서는 현저한 차이가 없었으나 외국인 비감염자의 경우 CD4백분율이 43.6%, CD8 T림프세포의 절대수가 560으로 한국인과 약간의 차이가 있었다. 따라서 HIV감염자관리를 위한 면역지표측정시험에서의 각종수치의 정확한 해석을 위하여서는 한국인 비감염자수치를 고려해야할 것으로 판단된다. Several studies showed that the immunological factors such as CD4+ cell number, CD4%, CD8+ cell number and CD4/CD8 ratio and the serological factors such as β²-microglobulin(β²-MG), neopterin, soluble CD4, and soluble CD8 are related to the risk of development of AIDS. Especially, the CD4+ cell counts have been used to monitor progresson of HIV disease, to stratify, and to follow patients in clinical trials. Recently, the Centers for Disease Control and Prevention(CDCP) in USA has made the CD4+ cell count as a part of the classification of HIV disease. It is composed of 3 categories such as 1, 2, and 3 which asr ≥500/㎣, 200/㎣ ≥and <500/㎣, and < 200/㎣, respectively. In this study, to estimate the differences of immunological factors between HIV-infected and normal human groups in Korea, CD4+ T and CD8+ T cells, and the CD4/CD8 ratio were measured in 185 HIV-infected subjects and 140 healthy adult subjects. The lymphocyte subsets such as CD4+ T and CD8+ T were analysed by flow cytometer(FACStar) with two-color immunofluorescent stain using monoclonal antibodies such as anti-CD4 and anti-CD8 antibodies. The absolute numbers and percentages of CD4+ T and CD8+ T and the CD4/CD8 ratio of HIV infected persons were 462±277/㎣, 18.2±7.7%, 1,170±534/㎣, 47.0±10.6% and 0.43±0.26 whereas those of uninfected persons were 886±299/㎣, 32.9±7.0%, 730± 259/㎣, 26.8±6.4% and l.31±0.46(P<0.01). In addition, estimating the reference values of peripheral blood lymphocyte subsets of Korean, the absolute numbers and percentages of CD4+ T and CD8+ T and the CD4/CD8 ratio of 140 healthy adults persons were measured and compared with those of foreigners. The reference ranges of CD4+ T cells, CD8+ T cells, CD4%, CD8%, and the CD4/CD8 ratio and 1.31t0.46, respectively. The significant differences were not observed when compared with those of foreigners. However a little difference was observed in the percentages of CD4+ T and the absolute numbers of CD8+ T between the normal values of Korean and those of foreigners were 43.6±8.9%, 560±230/㎣. This result can also be useful as a basic data for the treatment and surveillance of HIV-infected patients in Korea.

Optimization of Strain Gauge Position on Blades for Vibration Measurement

Choi, Byeong-Keun,Mignolet, Marc P. 경상대학교 해양산업연구소 2002 해양산업연구소보 Vol.15 No.-

This paper focuses on the formulation and validation of an automatic strategy for the selection of the locations and directions of strain gauges to capture at best the modal response of a blade in a series of modes. These locations and directions are selected to render the strain measurements as robust as possible with respect to random mispositioning of the gauges and gauge failures. The approach relies on the evaluation of the signal-lo-noise ratios of the gauge measurements from finite element strain data and includes the effects of gauge size. A genetic algorithm is used to find the strain gauge locations-directions that lead to the largest possible value of the smallest modal strain signal-to-noise ratio, in the absence of gauge failure, or of its expected value when gauge failure is possible. A fan blade is used to exemplify the applicability of the proposed methodology and to demonstrate the effects of the essential parameters of the problem, i.e. the mispositioning level, the probability of gauge failure, and the number of gauges.

Compare the vibration characteristics of the pipe defects and leak of pipes

Byeong-Keun Choi(최병근),Yong-Seok Kim(김용석),Sun-Hwi Park(박선휘),Jeong-Min Ha(하정민),Seon-Hwa Kim(김선화) 한국소음진동공학회 2016 한국소음진동공학회 학술대회논문집 Vol.2016 No.4

Optimal Placement of Strain Gauge for Vibration Measurement

( Byeong Keun Choi ),( Marc P. Mignolet ) 경상대학교 해양산업연구소 2003 해양산업연구소보 Vol.16 No.-

Optimal design of rotor-bearing systems using immune-genetic algorithm

Choi, Byeong-keun,Yang, Bo-suk 부경대학교 음향진동공학연구소 2001 音響振動工學硏究所 硏究報告 Vol.6 No.-

Diagnosis of Cryogenic Pump-Motor Systems Using Vibration and Current Signature Analysis

Choi Byeong-Keun,Kim Hak-Eun,Gu Dong-Sik,Kim Hyo-Jung,Jeong Han-Eul The Korean Society of Mechanical Engineers 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.7

In general, to send out natural gas via a pipeline network across the nation in LNG terminal, high-pressure cryogenic pump supply highly compressed LNG to high-pressure vaporization facilities. The Number of cryogenic pumps determined the send-out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high vibration at cryogenic pumps-motor system in LNG terminal, vibration spectrum analysis and motor current signature analysis have been performed together. Through the analysis, motor rotor bar problems are estimated by the vibration analysis and confirmed by the current analysis. So, it is demonstrated through the case study in this paper, how performing vibration analysis and current signature analysis together can reliable diagnosis rotor bar problems in pump-motor system.

OPTIMIZATION OF INTENTIONAL MISTUNING PATTERNS FOR THE REDUCTION OF THE FORCED RESPONSE EFFECTS OF UNINTENTIONAL MISTUNING

Byeong-Keun Choi,Jeff Lentz,Alejandro Rivas-Guerra,Marc P. Mignolet 한국동력기계공학회 2002 한국동력기계공학회 학술대회 논문집 Vol.- No.-

The History of the instiute of marine industry : Research papers ; Pattern Optimization of Intentional Mistuning for Bladed dik by Genetic Algorithm

( Byeong Keun Choi ),( Marc P. Mignolet ) 경상대학교 해양산업연구소 2002 해양산업연구소보 Vol.15 No.-