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부분적으로 유체가 채워진 원통형 관내의 외팔보 진동특성에 관한 실험적 연구
권대규,유계형,소순선,이성철 전북대학교 공학연구원 ( 구 전북대학교 공업기술연구소 ) 2003 工學硏究 Vol.34 No.-
This paper presents the vibration characteristics of an intelligent cantilever beam in contact with fluid using PZT actuator and PVDF film. The effect of liquid level on free vibration of composite beam in a partially liquid-filled circular cylinder is investigated. The dynamic behaviors of a flexible beam-water interaction system are examined. The coupled system is subject to an undisturbed boundary condition in the fluid domain. In the vibration analysis of wetted beam, the decoupled analyses between beam and fluid have been conventionally employed by considering firstly the composite beam vibration in air and secondly performing the correction taking account for surrounding fluid effects. That is, this investigation was to look at how natural frequencies, mode shapes, and damping are affected by liquid level variations. Using the coupled modal reanalysis method employing the governing equations and the clamped-free and free-free boundary conditions, the vibration analysis of beam in contact with fluid is performed. We also carried out the experimental verification about reliability of theoretical methods to inclusive vibration analysis of the fluid-structure system with PZT actuator and PVDF film. It was found that the coupled natural frequencies decrease with the fluid level for the identical composite beam due to added mass effect.
임상화학 검사의 Delta Check System 개발 및 정도관리 효율성 검토
권계철,임춘화,김문희,박연보 충남대학교 의과대학 지역사회의학연구소 2001 충남의대잡지 Vol.28 No.1
Background : The application of the delta check in tests in general chemistry detects both random and clerical errors, thus enhancing the reliability of tests. However, since this approach adds the burden of confirming the results to the laboratory, it has the disadvantage of lengthening the turn around time of tests. We speculated that an online delta check system needed to reduce the turn around time. We developed delta quality control system and evaluated its effectiveness of quality control in clinical chemistry. Methods : We developed an online delta check system based on the client-server paradigm. We used IBM PentiumⅢ PC as server and as clients. The database system used was powerbuilder 6.0. Results : In the system we developed, delta screening was performed when test results were input to the computer. The decision over the delta screening was made by comparing it against patient's clinical information and cumulative results within the same screen. Conclusions : The developed delta check method made it available to reduce the turn around time previously spent on delta screening by eliminating the batch processing of tests which was needed in previous approaches separate query cumulative results and patient's clinical informations for screening purposes.
유계형,권대규,정경훈,이성철 한국산업안전학회 2003 한국안전학회지 Vol.18 No.1
This paper presented an experimental modal analysis of clamped perforated rectangular plates submerged in water. The penetration of holes in the plates had a triangular pattern with P/D(pitch to diameter) 1.750, 2.125, 2.500, 3.000 and 3.750. The natural frequencies of the perforated plates in air were obtained by the Rayleigh-Ritz method and compared with the experimental results. Good agreement was obtained between the analytical solution and experimental result. The experimental results in water showed that the mode shapes are not sensitive to the depth of submergence. The natural frequencies were shown to decrease drastically once the perforated plates come in contact with water. However, the natural frequencies decrease with the depth of submergence until a certain depth is reached, and become the asymptotic values beyond this depth of submergence. The depth of submergence did not affect the damping ratio greatly.
유체로 연성된 직사각평판의 거리 변화에 따른 고유진동 해석
유계형,이명규,권대규,이성철 전북대학교 공학연구원 ( 구 전북대학교 공업기술연구소 ) 2002 工學硏究 Vol.33 No.-
This study dealt with the experimental modal analysis of the perforated rectangular plate coupled with fluid. The natural frequencies of the perforated plate and solid plate in air were obtained by the analytical method based on the relation between the reference kinetic and maximum potential energy and compared with the experimental results. Good agreement between the results was found for the natural frequencies of the perforated plate in air. It was empirically found the natural frequencies of the perforated plate coupled with fluid. The transverse vibration modes, in-phase and out-of-phase, were observed alternately in the fluid-coupled system. Additionally, the effect of distance between perforated plate and solid plate on the fluid-coupled natural frequency was investigated.
말초혈액 조혈모세포 채혈 및 이식 후 생착에 관한 연구
손계성 ( Gye Sung Son ),권흥만 ( Heung Man Kwon ),권계철 ( Gye Cheol Kwon ) 대한임상검사과학회 2006 대한임상검사과학회지(KJCLS) Vol.38 No.1
Peripheral bood stem cell collection (PBSCC), including peripheral blood stem cell transplantation (PBSCT), has been utilized worldwide as a very beneficial treatment method instead of allogenic Bone Marrow Transplantation (BMT) because it has many advantages such as rapid bone marrow engraftment and hematopoietic recovery, easy and safe accessibility and lower risk of rejection compared with allogenic BMT. In order to identify most the observable parameter in PBSCC, we analyzed various hematological parameters before and after PBSCC, and evaluated the correlation between the time of bone marrow engraftment and the number of CD34+ cells. Thirteen patients, who underwent 54 PBSCCs from January, 2003 to August, 2004 at Chungnam National University Hospital due to various systemic neoplasms, were analyzed in aspects of various hematological parameters including CD34+ cells using by Flow Cytometry (FCM). PBSCC harvests are described below: Mononuclear cells (MNC) 2.3 ± 1.4×108/kg and CD34+ cells 0.63 ± 0.35×106/kg on average, respectively. There was a statistical significance in Hb and Hct before and after PBSCC, but not in WBC and platelet counts. The period to reach the hematological bone marrow engraftment was 13.4(10~21) days and 19.5(11~38) days according to the criteria of absolute neutrophile counts (ANC) ≥ 500/uL and platelet counts ≥50,000/μL in peripheral blood, respectively. There was a significant correlation between the numbers of CD34+ cell and ANC (p<0.05), and a borderline significance between MNC and ANC (p=0.051). We found that a group of patients, who were infused with CD34+ cells more than 3.5×106/kg, reached more rapidly the period of bone marrow engraftment in platelet counts (p=0.040). This present study suggested that Hb and Hct were the most useful parameters and should be closely monitored before and after PBSCC, that a PBSCT with the dosage of more than 3.5×106/kg of CD34+ cells was needed to perform successful bone marrow engraftment, and additionally that platelet counts could be more useful in indicating bone marrow engraftment than ANC.
( Ji Won Gye ),( Ji Yeon Yoo ),( Sung Ku Ahn ),( Ji Eun Kwon ),( Chan Hee Nam ),( Ji Seok Kim ),( Jee Young Kim ),( Byung Cheol Park ),( Myung Hwa Kim ),( Seung Phil Hong ) 대한피부과학회 2013 대한피부과학회 학술발표대회집 Vol.65 No.2
Background: Non-melanoma skin cancers are caused mainly by prolonged UV exposure. However, there is no effective prevention other than avoiding sun exposure. Recently, ablative fractional laser(FL) treatment is actively being carried out for facial rejuvenation. Objectives: We elucidated whether the occurrence of skin tumors caused by exposure to UV can be decreased by multiple sessions of ablative CO2 FL. Methods: Two groups of hairless mice were treated with either ablative CO2 FL or nothing at 3-week intervals during the 20 weeks of UV exposure period. At the 30-week, representative tumors were taken to evaluate the type of tumor and check the mRNA expression levels of the MMP-13 and type-1 procollagen. In addition, we evaluated the change of skin barrier function at 12 weeks and 20 weeks. Results: At 30 weeks, the UV plus FL treated group(group I) showed a significantly lower average size of tumor and a lower occurance rate of tumors than the UV only treated group(group II). Tumors in the group II showed more malignant progression. And the groups II showed significantly greater trans-epidermal water loss than the group I. The group II showed significantly decreased collagen and elastic contents than the group I. The group I presented a higher mRNA level of type-1 procollagen, and a lower level of MMP-13 than the group II. Conclusion: Ablative CO2 FL can be effective for not only skin rejuvenation but also for prevention of skin tumors induced by UV.