• 반도체디스플레이기술학회지
• /
• 제10권1호
• /
• pp.43-49
• /
• 2011

In this study, the dynamic characteristics of an air spring connected with an external chamber through a flexible tube are examined. The uncoupled dynamic parameters of the air spring are identified through experiments, followed by the suggestion of a model-based approach to obtain the remaining coupled dynamic parameters using the various frequency response functions derived in PART I paper [1]. To improve or control the damping characteristics of the air spring, this vibration isolation air spring system is physically established in laboratory scale. And we attempt to identify various parameters used to describe to air spring system by both theoretically [1] and experimentally, which is performed in this report. The damping parameter of the tube system is identified through experiments on the system incorporated with the air cylinder, and a nonlinear regression procedure is employed to find solutions. The resulting value is used to expect the frequency response function of dynamic pressure in the top chamber (air spring) with respect to that in the bottom chamber (external chamber). Comparison with the experimental data supports the validity of the present estimation procedures. Also, the dynamic mechanism of the damping effects particularly in a low frequency range is investigated through this experimental endeavor.

• 한국소음진동공학회논문집
• /
• 제18권4호
• /
• pp.411-423
• /
• 2008

Pneumatic vibration isolator has a wide application for ground-vibration isolation of vibration-sensitive equipments. Recent advances In precision machine tools and instruments such as nano-technology or medical devices require a better isolation performance, which can be efficiently done by precise modeling- and design- of the isolation system. This paper will discuss an efficient transmissibility design method for pneumatic vibration isolator by employing the complex stiffness model of dual-chamber pneumatic spring developed in our previous research. Three design parameters of volume ratio between the two pneumatic chambers, the geometry of capillary tube connecting the two pneumatic chambers and finally the stiffness of diaphragm necessarily employed for prevention of air leakage were found to be important factors in transmissibility design. Based on design technique that maximizes damping of dual-chamber pneumatic spring, trade-off among the resonance frequency of transmissibility, peak transmissibility and transmissibility in high frequency range was found, which was not ever stated in previous researches. Furthermore this paper will discuss about negative role of diaphragm in transmissibility design. Then the design method proposed in this paper will be illustrated through experiment at measurements.

• Structural Engineering and Mechanics
• /
• 제61권5호
• /
• pp.645-655
• /
• 2017

To determine the seismic applicability of a long-span railway concrete upper-deck arch bridge with concrete-filled steel-tube (CFST) rigid skeleton ribs, some fundamental principles and seismic approaches for long-span bridges are investigated to update the design methods in the current Code for Seismic Design of Railway Engineering of China. Ductile and mixed isolation design are investigated respectively to compare the structural seismic performances. The flexural moment and plastic rotation demands and capacities are quantified to assess the seismic status of the ductile components. A kind of triple friction pendulum (TFP) system and lead-plug rubber bearing are applied simultaneously to regularize the structural seismic demands. The numerical analysis shows that the current ductile layout with continuous rigid frame approaching spans should be strengthened to satisfy the demands of rare earthquakes. However, the mixed isolation design embodies excellent seismic performances for the continuous girder approaching span of this railway arch bridge.

• 한국소음진동공학회논문집
• /
• 제18권1호
• /
• pp.110-122
• /
• 2008

Pneumatic vibration isolator typically consisting of dual-chamber pneumatic springs and a rigid table are widely employed for proper operation of precision instruments such as optical devices or nano-scale equipments owing to their low stiffness- and high damping-characteristics. As environmental vibration regulations for precision instruments become more stringent, it is required to improve further the isolation performance. In order to facilitate their design optimization or active control, a more accurate mathematical model or complex stiffness is needed. Experimental results we obtained rigorously for a dual-chamber pneumatic spring exhibit significantly amplitude dependent behavior, which cannot be described by linear models in earlier researches. In this paper, an improvement for the complex stiffness model is presented by taking two major considerations. One is to consider the amplitude dependent complex stiffness of diaphragm necessarily employed for prevention of air leakage. The other is to employ a nonlinear model for the air flow in capillary tube connecting the two pneumatic chambers. The proposed amplitude-dependent complex stiffness model which reflects dependency on both frequency and excitation amplitude is shown to be very valid by comparison with the experimental measurements. Such an accurate nonlinear model for the dual-chamber pneumatic springs would contribute to more effective design or control of vibration isolation systems.

• 한국산학기술학회논문지
• /
• 제17권11호
• /
• pp.421-431
• /
• 2016

본 연구는 연하장애 환자의 삶의 질 향상을 목적으로 연하장애 환자의 우울, 사회적 고립감, 생의 의미와 삶의 질수준을 파악하고, 삶의 질의 영향요인을 확인하고자 시도되었다. 연구대상은 서울, 인천, 경기 지역에 소재한 종합병원과 재활병원 등 8개 기관에서 뇌졸중, 퇴행성 신경계 질환으로 인하여 연하장애가 발생한 환자 총87명을 대상으로 하였다. 자료수집기간은 2015년 2월부터 4월까지였으며, 연구도구는 CES-D, RULS, PIL, SWAL-QOL을 사용하였다. 수집된 자료는 SPSS 22.0 통계프로그램을 이용하여 기술통계, t-test, ANOVA, Pearson's correlation, Stepwise multiple regression으로 분석하였다. 연구 결과 우울이 있는 군은 대상자의 20.7%였고, 보통 이상의 사회적 고립감을 느끼는 군 92.0%, 실존적 공허상태에 있는 군이 64.4% 였다. 즉, 대다수의 대상자들이 사회적 고립감을 경험하고 실존적 공허상태에 있었으며, 삶의 질의 평균 점수는 158.89(35.97)점이었다. 연하장애 환자의 삶의 질 영향요인을 확인한 결과, 경관급식의 경우가 정상식이보다 삶의 질이 유의하게 낮았고(${\beta}=-0.57$, p<.001), 생의 의미가 낮아 실존적 공허상태에 있는 경우(${\beta}=0.19$ p=.014)가 삶의 질이 낮았다. 30-49세의 연령은 80세 이상보다 삶의 질이 높았으며(${\beta}=0.26$, p=.001), 대학교 수준 이상의 교육수준이 무학에 비해 삶의 질이 높았다(${\beta}=0.17$, p=.032). 이 중 연하장애 환자의 삶의 질에 가장 많은 영향을 주는 변수는 경관급식이었고 (${\beta}=-0.57$, p<.001), 이러한 4개의 변수는 연하장애 환자의 삶의 질에 대해 50.7%(F=28.84 p=.031)의 설명력을 나타냈다. 그러므로 연하장애 환자의 삶의 질을 높이기 위해 생의 의미를 높일 수 있는 중재 프로그램의 개발과 함께, 경관급식 환자의 삶의 질이나 정서 상태를 확인할 수 있는 후속연구가 필요하다.

• 한국수산과학회지
• /
• 제47권2호
• /
• pp.129-134
• /
• 2014

Two neuropeptides were purified from the acidified tube feet extract of the starfish Asterias amurensis by C18 reversed phase and size-exclusion high-performance liquid chromatography (HPLC). The tube feet extract and the purified peptides (AST-I and AST-II) showed potent contractile activity on dorsal retractor muscle (DRM) of the starfish Asterina pectinifera and intestine (smooth muscle) of the panther puffer Takifugu pardalis. Treatment of the purified peptides with dithiothreitol (DTT) for 60 min at $37^{\circ}C$ significantly altered their retention times, suggesting that these compounds contained disulfide bonds. The molecular weights of AST-I and AST-II were determined to be 2064.2 Da and 6137.2 Da, respectively, by MALDI-TOF mass spectrometry.

• 미생물학회지
• /
• 제16권3호
• /
• pp.111-121
• /
• 1978

About 40 temperature-sensitive mutants have been isolated as a preliminary step to study the spore germination, the cell cycle, and the control of macromolecular synthesis in Aspergillus nidulans. To obtain temperature-sensitive mutants rapidly and effectively, the selective enrichment method using antifungal antibiotic nystatin was developed. Based on the data which had applied to the concentration of auxotrophic mutants by the earlier investigators, the optimal concentration and the time of treatment at the nonpermissive temeprature were determined as 50 to 100 units per ml and 4.5 hr., respectively. Out of 41 ts mutants assigned to the strain symbol PK, thirteen that seemed to be arrested at the earlystage of spore germination were subjected to the further cytological and genetic analysis. Elght of these mutants are able to form germ tube and five not. Staining with acid fuchsin for the 5PK strains shows that one irreversible mutant, PK6 strain able to form germ tube, accumulate mitotic spindle, being arrested in mitosis. Another PK15 and PK23 strain have more than one intact nucleolus without germ tube formation at the restrictive temperature. the temperature-senstive mutation in PK12 strain, the onlystrain which is able occurred in certain gene specific for the germination of spore. All of the ts markers are recessive and complement each other in heterokaryon between two different ts markers at the restrictive temperature.

• 대한수의학회지
• /
• 제18권1호
• /
• pp.19-22
• /
• 1978

In order to isolate and identify Anaplasma bodies, two dairy cattle were inoculated with the whole blood of Korean cattle reacted to capillary tube agglutination test (Ana-test). The results obtained are as follows: 1. In the infected dairy cattle, Anaplasma bodies were first detected between 30 to 40 days post infection. 2. The isolates were identified as Anaplasma centrale on the basis of morphology of infected anaplasma bodies in erythocytes.

• 한국지반환경공학회 논문집
• /
• 제7권6호
• /
• pp.13-22
• /
• 2006

지난 30여년간 지오텍스타일은 토목분야의 건설현장에서 필터 및 배수기능을 위한 효과적인 재료로 활용되어 왔으며, 최근에는 다양한 환경 분야에서도 그 활용이 증가되고 있다. 지오텍스타일 튜브공법은 지오텍스타일의 필터 및 배수기능을 복합적으로 활용하는 공법으로 과거의 모래주머니, 훼브릭 폼, 게비언 등의 개념에서 최근 수리학적 채움기법을 적용하여 해안침식방지 구조물, 슬러지의 탈수, 오염물질의 격리처리 구조물 등의 신구조물 공법으로 자리매김 하고 있다. 본 연구에서는 지오텍스타일 튜브와 지반재료와의 복합구조물의 거동 및 설계인자에 대하여 2차원 한계평형 및 평면변형 해석방법을 통하여 분석하였다. 2차원 한계평형이론을 통하여 설계영향인자 및 현장여건에 따른 지오텍스타일 튜브 복합 구조물의 지반공학적 안정성을 분석하였으며, 지오텍스타일 튜브 전용해석 프로그램인 GeoCoPS를 이용한 2차원 평면변형 해석에서는 지오텍스타일 튜브 구조물의 설계 및 시공기법에 대하여 검토하였다. 2차원 한계평형해석 및 평면변형해석 방법을 통한 분석결과, 세가지 형태의 지오텍스타일 튜브구조물 모두 안정성을 확보하고 있으며, 지오텍스타일의 소요인장강도는 151kN/m, 펌핑압은 최대 22.7kN/m로 도출되었다.

• 대한수의학회지
• /
• 제40권2호
• /
• pp.339-343
• /
• 2000

Isolation and identification, prevalence and density of Setaria microfilariae(mf) were investigated in the blood of 406 cattle slaughtered at the abatoirs in Yungnam province from February 1999 to March 2000. Nine ml of blood from the jugular vein was collected in a test tube including EDTA respectively. The blood was mixed(10 : 1) with 0.2% Saponin in saline solution. This mixture was diluted again(1 : 10) with saline solution and stirred. This diluted mixture was filtered using Millipore membrane filter with a pore size of $3.0{\mu}m$. Mf were recovered from the membrane in saline solution. Mf isolated were identified as Setaria digitata on the basis of morphologic characteristics. Infection rate of the mf of total 406 cattle was revealed as 6.40%. Seasonal prevalences of the mf were presented 9.46%(7/74) in Autumn, 7.05%(11/156) in Summer, 4.65%(4/86) in Winter and 4.44%(4/90) in Spring respectively. Average density of the mf of every 9ml blood in 26 positive cattle was revealed as 170(2-641) worms. Seasonal densities of the mf of 9ml blood were presented average 361(160-641) worms in Autumn, 205(16-620) worms in Summer, 108(6-204) worms in Spring, 6(2-11) worms in Winter respectively.