• International Journal of Concrete Structures and Materials
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• 제7권4호
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• pp.265-271
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• 2013

Prestressed concrete cylindrical pipe (PCCP) has been widely used for the distribution of water in communal, industrial, and agricultural systems for a long time. However, as it deteriorates, structural failures have been experienced. Replacing the entire existing PCCP with partial damages is not an economical method. Currently, as a cost effective repairing method, a new approach using fiber reinforced polymer (FRP) has been applied. A new design procedure of this method was proposed considering various kinds of loading condition. However, it is not easy to apply this method for design purpose due to its complex procedures. The objective of this study is to provide a new design criteria and process for PCCP rehabilitation with FRP. Through this method, the appropriate quantities of FRP layers will be decided after examining of limit states of deteriorated PCCP. For this purpose, two deterioration conditions are assumed; fully deteriorated and partially deteriorated. Different limit states for each case are applied to decide the quantities of attached FRP. The concept of "margin of safety" is used to judge whether the design results are within the optimal ranges to satisfy all limit states.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.369-372
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• 1997

Wire Ion Plasma Source (WIPS) is a plasma device which has a thin wire anode, a coaxially-set cylindrical cathode and electrodes located in both ends of the cylinder. The potential between the anode and cathode changes logarithmically by this electrode configuration. This electrode configuration enables high-density plasma to produce even at a low anode voltage. Since the electrode configuration is axially symmetric and long. plasma with axially uniform number density can be produced. Using particle-in-cell(PIC) and Monte Carlo collision(MCC), we investigate the traiectory of electrons and the characteristics of D.C. discharge in Wire ton Plasma Source.

• E2M - 전기 전자와 첨단 소재
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• 제8권6호
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• pp.721-726
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• 1995

In this paper, reduction characteristics of NOx gas produced from diesel engine combustion is studied by using pulse corona discharge. Nox concentration of 1900ppm (NO 1870, NO$\sub$2/ 30 ppm, N$\sub$2/ balance gas) was controlled in a fixed quantity of 280ppm, using a flow meter. Reactors are composed of cylinder type. NOx reduction rate is investigated with discharge electrode diameter[0.5,1,3,4.phi.], reactor length [130,300mm], reactor materials[Copper, Poly Vinyl Chloride] and Input voltage[DC, AC, DC Pulse square voltage]. In the result, NOx reduction rate is the best of all in copper reactor, small electrode diameter[0.5.phi.], DC pulse voltage and long reactor[300mm]. Then Teduction rate of NOx is about 93%.

• 생약학회지
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• 제20권3호
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• pp.162-169
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• 1989

Tissue culture of the roots of Panax ginseng was carried out to enhance the production of ginseng callus as well as to increase its contents of ginsenosides. A long cylinder type callus mass was formed when cultured IK callus by rotary shaking culture method, the growth ratio of the callus being 7.71 which was approximately 4 fold higher than those obtained by other culture methods. Ginsenosides $Rg_1$, Re and $Rb_1$ could be detected from the callus mass by TLC, however, their total contents were revealed to be approximately 9% compared to that of the fresh ginseng root equivalent by HPLC analysis,.

• 한국지진공학회논문집
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• 제26권4호
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• pp.149-156
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• 2022

Magneto-Rheological Fluid (MRF) is a functional fluid in which flow characteristics change into magnetic force due to its magnetic particles. When the semi-active control device does not use MRF for a long time, precipitation of magnetic particles and abnormal control force occur. Thus, Electro Magneto-Rheological Fluid (EMRF), which improves the precipitation of magnetic particles for MRF and exhibits existing control performance, was developed in this study. First, the optimal mix proportion ratio was selected by conducting a precipitation experiment and a controlled force test by varying the content of grease based on the existing MRF components. Also, EMRF was applied to the shear-type damper to evaluate the control performance when applied to the control device. The cylinder-type damper was developed to apply to the structure, and control performance evaluation was conducted. The result confirmed that the precipitation of the magnetic particles was improved, while the damper using EMRF exhibited excellent control performance.

• Journal of applied mathematics & informatics
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• 제41권3호
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• pp.487-510
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• 2023

We propose a mathematical model which describes the frictional contact between a piezoelectric body and an electrically conductive foundation. The behavior of the material is described with a linearly electro-viscoelastic constitutive law with long term memory. The mechanical process is dynamic and the electrical conductivity coefficient depends on the total slip rate, the friction is modeled with Tresca's law which the friction bound depends on the total slip rate with taking into account the electrical conductivity of the foundation both. The main results of this paper concern the existence and uniqueness of the weak solution of the model; the proof is based on results for second order evolution variational inequalities with a time-dependent hemivariational inequality in Banach spaces.

• 한국대기환경학회지
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• 제34권2호
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• pp.331-341
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• 2018

Hazardous air pollutants(HAPs) in the atmosphere are regulated as major air pollutants in Korea by the Air Pollution Control Act. In order to manage and control HAPs, accurate standards, which are traceable to the International System of Units(SI), are required. In this study, primary standard gas mixtures(PSMs) of volatile organic compounds(VOCs) which are specified as HAPs were developed at $1{\mu}mol/mol$ levels. The selected fourteen VOCs include Benzene, Toluene, Ethylbenzene, m-Xylene, Styrene, o-Xylene, Chloroform, 1,1,2-Trichloroethane, Trichloroethylene, Tetrachloroethylene, 1,1-Dichloroethane, Carbon tetrachloride, 1,3-Butadiene, and Dichloromethane. The HAPs PSMs were gravimetrically prepared in aluminum cylinders and their consistency was verified within the relative expanded uncertainty of 0.71% (k=2). Potential adsorption loss onto the internal surface of cylinders was estimated by cylinder-to-cylinder division method. No adsorption loss was observed within the uncerainty of 0.53%. The long-term stability of the HAPs PSMs was evaluated comparing with freshly prepared HAPs PSMs. The HAPs PSMs were stable for one year within the uncertainty of 0.38%. The final uncertainty of the PSMs was determined by combining the preparation uncertainty, verification uncertainty, and stability uncertainty. Finally, traceable and stable HAPs PSMs at $1{\mu}mol/mol$ levels were developed with the uncertainty of less than 0.76% in high-pressure aluminum cylinders.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.141-144
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• 1997

Femoral neck anteversion is the angle between the neck and the knee axis projected on a plane perpendicular to the longitudinal axis. Conventional methods that use cross-sectional Computed Tomography(CT) images to estimate femoral anteversion have several problems because of the complex 3D structure of the femur. These are the ambiguity of defining the longitudinal axis, the femoral neck axis and condylar line, and the dependence on patient positioning. Especially the femoral neck axis that is known as a major source of error is hard to determine from a single or multiple 2D transverse images. So we developed a new method for measuring femoral anteversion by 3D modeling method. In this method, femoral head is modeled as a sphere. The center of femoral neck is the mid-point of the 2D reconstructed oblique image in the femoral neck part. Then neck axis is a line connecting foregoing two centers. We model the longitude of femur as a cylinder, and the long axis is defined from the fitted cylinder. The knee axis which is tangent to the back of the femoral condyles is easily determined by table-top method. By the definition of femoral anteversion, the femoral anteversion is easily calculated from this model.

• 대한방사선기술학회지:방사선기술과학
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• 제32권2호
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• pp.213-218
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• 2009

감마선 원천핵을 두 개의 금속 평행판 사이, 실린더나 구와 같은 유한한 공간 내부에 놓았을 때 에너지 준위폭이 어떻게 변경되는가에 대하여 이론적으로 조사했다. 2개의 금속판에 의해 뒤쪽 산란된 감마선이 원천핵에 재흡수됨으로써 $^{133}Cs$핵의 여기상태(81 keV)의 에너지폭은 평행판 간격이 1.0 mm일 때 4.2 K에서 3.7% 정도 감소됨을 볼 수 있었다. 여기서 금속판은 두께 0,5 mm, 반경이 3 cm이며 금으로 만들었다. 반경 1.0 mm, 두께 0.5 mm, 길이 5 cm의 실린더 금판에 의해 뒤쪽 산란되었을 때에는 4.2 K에서 6.5% 에너지 폭이 좁아지는 결과를 얻었다. 또한, 두께 0.5 mm, 반경 1.0 mm의 금으로 된 구 안에 원천핵을 놓았을 때 4.2 K에서 18.2% 에너지준위 폭이 감소하였다. 이러한 에너지 준위 폭의 감소는 그 준위의 반감기가 연장된 것을 의미한다.

• 대한전자공학회논문지TE
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• 제42권4호
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• pp.27-32
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• 2005

액체 밸브는 실린더 부분과 액체부분으로 분리 또는 일체형 구조로 되어 있으며, 불소수지 Packing에 STS(stainless) 축을 삽입하여 실린더 머리에 연결된 구조로 되어있어 액체를 주입과 차단시 상하왕복 작동으로 인해 불소수지 패킹과 STS 축 사이에 마찰로 인해 액체의 누설로 인해 작업 환경 저하와 각 부품교체로 인한 작업능률의 저하로 생산성이 목표치에 이르지 못하고 있다. 이에 따라 액체밸브 설계에서부터 재질, 구조변경 등의 필요성이 있으며, 설계, 재질선택, 구조변경 등을 연구하였다. 본 논문은 기존의 문제점을 근본적으로 해소하고자, 피스톤과 연동되는 진동의 개발로 피스톤이 쉽게 마모되는 것을 방지하여 장 수명을 충족시키고 누설방지를 제공하는데 목적이 있다. 액체 토출후 노즐 팁에 액체가 잔류하는 것을 방지할 수 있도록 피스톤이 후퇴 시 이를 흡입시킬 수 있는 기능을 부가하여 방울 맺힘을 방지함을 목적으로 하고 있다.