• 한국해양공학회지
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• 제13권3호통권33호
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• pp.100-107
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• 1999

Due to the high temperature and pressure, the materials of pipeline in power plant are degraded by creep damage. So far, many conventional measurement techniques such as replica method, electric resistance method, adn hardness test method for creep damage have been used. Among them, the replica method has mainly been used for the inspection of components. But this technique is restricted to the applications at the surface of the objects and cannot be used to material inside. In this paper, the measuring methods of evaluation by using ultrasonic attenuation and electric resistance for the creep detection of creep damage in the form of cavities on grain boundaries or intergranular microcracks were carried out. Absolute measuring method of quantitave ultrasonic attenuation technique for 1Cr0.5Mo material degradation was analyzed for determining the creep degradation steps using life prediction formula. As a result of measurement for creep specimens, we founded that the coefficient of utrasonic attenuation was increased as the increase of creep life fracton(${phi}c$) and the decreasing rate of wlwctric resistance was also increased.

• 한국전자통신학회논문지
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• 제8권3호
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• pp.403-408
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• 2013

본 연구는 자동차 브레이크 패드 생산 공정에서 컨베어벨트 실려가는 차종별 패드의 유형을 자동 판별하고 표면의 균열을 검사하는 시스템을 개발한다. 브레이크 패드는 여러 혼합제로 고열, 고압 성형하여 만든다. 패드생성과정에서 패드 표면의 균열 및 손상이 발생한다. 본 연구에서는 불량품을 검출하는데 적합한 시스템 구축하고 응용소프프웨어 개발을 한다. 패드 표면의 균열이나 손상 부위는 인공조명을 비출 때 그림자를 생성하게 되며 이를 컴퓨터 비전 기술을 활용하여 검출한다.

• Journal of Welding and Joining
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• 제30권6호
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• pp.36-41
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• 2012

General condensers consist of many tubes supported by tube sheets and support plates to prevent the deflection of the condenser tubes. When a fluid at high pressure and temperature runs over the tubes for the purpose of transferring heat from one medium to another, the tubes vibrate and their surface comes into contact with the support plates. This vibration causes damage to the tubes, such as cracks and wear. We propose an ultrasonic guided wave technique to detect the above problems in the support plate region. In the proposed method, the ultrasonic guided wave mode, L(0,1), is excited using an internal transducer probe from a single position at the end of the tube. In this paper, we present a preliminary experimental verification using a super stainless tube and show that the defects can be discriminated from the support signals in the support region.

• 비파괴검사학회지
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• 제33권6호
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• pp.519-523
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• 2013

A steam generator (SG) tube is an important component of a nuclear power plant (NPP). It works as a pressure boundary between the primary and secondary systems. The integrity of a SG tube can be assessed by an eddy current test every outage. The eddy current technique(adopting a bobbin probe) is currently the main technique used to assess the integrity of the tubing of a steam generator. An eddy current signal analyst for steam generator tubes continuously analyzes data over a given period of time. However, there are possibilities that the analyst conducting the test may get tired and cause mistakes, such as: missing indications or not being able to separate a true defect signal from one that is more complicated. This error could lead to confusion and an improper interpretation of the signal analysis. In order to avoid these possibilities, many countries of opted for automated analyses. Axial ODSCC (outside diameter stress corrosion cracking) defects on the tubes of OPR1000 steam generators have been found on the tube that are in contract with tube support plates. In this study, automated analysis software called CDS (computer data screening) made by Zetec was used. This paper will discuss the results of introducing an automated analysis system for an axial ODSCC on the tubes of an OPR1000 steam generator.

• 한국멀티미디어학회논문지
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• 제21권2호
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• pp.261-270
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• 2018

Hearing-impaired people are increasing rapidly due to the global aging trend. Early detection of hearing loss requires an easy-to-use audiometry device for the public. Existing audiometry systems were developed as PC-based, PDA-based, or smartphone apps. These devices were often dependent on specific software platforms and hardware platforms. In this paper, we tried to improve software platform compatibility by using cross platform, and tried to implement IoT-based pure tone audiometry device which does not require sound pressure level correction due to hardware differences. Pure tone audiometry is available in a variety of ways depending on the type of hearing loss and age. Using the IoT-based audiometry device implemented in this paper, it will be possible for an app developer who lacks hardware knowledge to easily develop an app with various scenarios for hearing screening. The results of this study will contribute to overcoming the software and hardware dependency in the development of IoT-based healthcare device.

• 대한기계학회논문집B
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• 제28권3호
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• pp.315-323
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• 2004

An electrical cascade impactor is a multi-stage impaction device to separate airborne particles into aerodynamic size classes using particle charging and electrical detection techniques. A Faraday cage and an aerosol charger, which are basic components of the electrical cascade impactor, were designed and evaluated in this study. The low-level current response of the Faraday cage was investigated with changing particle size and air flow rate by using sodium chloride (NaCl) particles. The response of the prototype Faraday cage was very similar to that of a commercial aerosol electrometer (TSI model 3068) within ${\pm}$5% for singly-charged particles. The response linearity of the prototype Faraday cage could be extended up to flow rate of 30 L/min. For the performance evaluation of the aerosol charger the monodisperse liquid dioctyl sebacate (DOS) particles, with diameters of 0.1∼0.8$\mu\textrm{m}$, were generated using spraying from an atomizer followed by evaporation-condensation process. Typical performance parameters of the aerosol charger such as P$.$n, wall loss, and elementary charges per particle were evaluated. The performance of the prototype aerosol charger was found to be close to that of the aerosol charger used in an electrical low pressure impactor (ELPI, Dekati).

• 한국공작기계학회논문집
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• 제12권2호
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• pp.23-30
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• 2003

It is very important to detect and evaluate the surface or subsurface flaws because of their influences on mechanical properties of materials. Rayleigh wave and creeping wave are commonly used for the detection of surface and subsurface flaws. These techniques, however, have following problems. Each amplitudes are remarkably affected by the surface condition and evaluation of echo pattern is usually difficult because shear wave mode propagate in the material at the same time. On the other hand, surface SH-wave which is horizontally polarized shear wave traveling along near surface layer is an attractive technique for the surface or subsurface material characterization and this technique is useful to solve the problems mentioned above. In this paper, The stability and transmission coefficient of SH waves through a viscous fluid layer is theoretically studied and simulated. Its results agreed well with the theoretical expectation for the experimental verification. These experimental results show that viscosity of couplants, thickness of couplant and surface roughness are closely related to transfer efficiency in surface SH angle beam method.

• 대한약침학회지
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• 제9권3호통권21호
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• pp.117-129
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• 2006

Objectives : The aim of this study was to find optimal conditions for producing red ginseng from cultivated wild ginseng using the Turbo Mill. Methods : Characteristics of powdered cultivated wild ginseng based on various temperature settings of the Turbo Mill were observed, and changes in the content was measured by HPLC for various ginsenosides. Results : 1. The diameter of cultivated wild ginseng powder ground by the Turbo Mill was around 10${\mu}m$. 2. As the temperature rose, pressure, Specific Mechanical Energy(SME), and density decreased, whileas Water Solubility Index(WSI) increased. 3. As the temperature rose, super fine powder showed tendency to turn into dark brown. 4. Measuring content changes by HPLC, there was no detection of ginsenoside Rg3 and ginsenosideRg1, Rb1, and Rh2 concentrations decreased with increase in temperature. Conclusions : Super fine powder of cultivated wild ginseng produced by the Turbo Mill promotes easy absorption of effective ingredients by breaking the cell walls. Using this mechanism to produce red ginseng from cultivated wild ginseng, it yielded less than satisfactory results under the current experiment setup. Further researches are needed to verify more suitable condition for the production of red ginseng.

• 비파괴검사학회지
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• 제25권4호
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• pp.268-273
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• 2005

폐활량계(Spirometer)는 호흡하는 가스의 용적 유량의 순간적인 속도를 측정하는 의료기구로 폐의 기능시험과 환자 모니터링에 사용되며 용적 유량 신호를 합친 폐의 절대적인 용적변화를 측정한다. 본 논문에서는 환자를 대상으로 약한 호흡에서도 폐활량 측정이 가능하도록, 관성의 오차 및 압력의 오차에 영향을 거의 받지 않는 초음파 센서를 이용하여 송수신시 초음파 신호를 향상시켰으며, ARM 9207 프로세서를 사용하여 약한 호흡에도 정확하고 빠른 검출이 가능한 시스템을 구현하였다.

• 한국임상수의학회지
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• 제16권1호
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• pp.31-36
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• 1999

The aim of this study is to determine the phagocytosis-promoting factor(s) for feline peripheral blood polymorphonuclear cells (PMN) by culture supernatant from mono-nuclear cells (MNC) treated with egg white derivatives (EWD). The phagocytic activity of PMN was analyzed by a flow cytometry system. The EWD did not show direct effect on the phagocytic response of PMN. The phagocytic activity of PMN was enhanced by culture supernatant from MNC but not PMN treated with EWD. Therefore, it was suggested that the enhanced phagocytic activity of feline PMN could be mediated by humoral factor(s) released from MNC treated with EWD. Thus, the phagocytosis-promoting factor(s) in supernatant fraction from MNC culture treated with EWD were isolated by reverse phase high pressure liquid chromatography. The resulting supernatant fraction on 29.02 minutes of retention time showed high phagocytic activity of PMN. The molecular weight of this supernatant fraction was 16 to 18 kDa when analyzed by capillary electrophoresis. The isoelectric point was pH 5.76 when assessed by ion-exchange chromatography. These results suggest that EWD stimulates feline MNC to elaborate a phagocytosis-promoting factor, 16 to 18 kDa of molecular weight, which could be an important mediator for the enhancement of phagocytic activity of feline peripheral blood phagocytes. Further study will be needed to elucidate this phagocytic factor.