전혈을 이용한 혈소판 응집능검사의 임상적 유용성에 관한 고찰

하영주,채석래,전회선,김현태 大韓血液學會 1993 大韓血液學會誌 Vol.28 No.1

Advances and challenges in impedance-based structural health monitoring

Huynh, Thanh-Canh,Dang, Ngoc-Loi,Kim, Jeong-Tae Techno-Press 2017 Structural monitoring and maintenance Vol.4 No.4

Impedance-based damage detection method has been known as an innovative tool with various successful implementations for structural health monitoring of civil structures. To monitor the local critical area of a structure, the impedance-based method utilizes the high-frequency impedance responses sensed by piezoelectric sensors as the local dynamic features. In this paper, current advances and future challenges of the impedance-based structural health monitoring are presented. Firstly, theoretical background of the impedance-based method is outlined. Next, an overview is given to recent advances in the wireless impedance sensor nodes, the interfacial impedance sensing devices, and the temperature-effect compensation algorithms. Various research works on these topics are reviewed to share up-to-date information on research activities and implementations of the impedance-based technique. Finally, future research challenges of the technique are discussed including the applicability of wireless sensing technology, the predetermination of effective frequency bands, the sensing region of impedance responses, the robust compensation of noise and temperature effects, the quantification of damage severity, and long-term durability of sensors.

Early Detection of Intravenous Infiltration Using Multi-frequency Bioelectrical Impedance Measurement System: Pilot Study

Kim, Jaehyung,Shin, Beumjoo,Jeon, Gyerok The Korea Institute of Information and Commucation 2017 Journal of information and communication convergen Vol.15 No.2

The early detection of intravenous (IV) infiltration is necessary to minimize the injury caused by the infiltration, which is one of the most important tasks for nurses. For detecting early infiltration in patients receiving invasive vein treatment, bioelectrical impedance was measured using multi-frequency bioelectrical impedance. The impedance decreased significantly at infiltration, and then decreased gradually over time after infiltration. The relative impedance at 20 kHz decreased remarkably at infiltration, and then gradually decreased thereafter. In addition, the impedance ratio increased temporarily at infiltration and then gradually decreased over time. Furthermore, the impedance at each frequency decreased quantitatively over time. This indicates that IV solution leaking from the vein due to infiltration accumulates in the subcutaneous tissues. Moreover, slopes of log Z vs. log f differently decreased with increasing log f, indicating that the impedance exhibits different responses depending on the frequency.

Online Embedded Impedance Measurement Using High-Power Battery Charger

Yong-Duk Lee,Sung-Yeul Park,Soo-Bin Han IEEE 2015 IEEE transactions on industry applications Vol.51 No.1

<P>This paper presents a new functionality for high-power battery chargers by incorporating an impedance measurement algorithm. The measurement of battery impedance can be performed by the battery charger to provide an accurate equivalent model for battery management purposes. In this paper, an extended control capability of the onboard battery charger for electric vehicles is used to measure the online impedance of the battery. The impedance of the battery is measured by the following: 1) injecting ac current ripple on top of the dc charging current; 2) transforming voltage and current signals using a virtual α-β stationary coordinate system, a d-q rotating coordinate system, and two filtering systems; 3) calculating ripple voltage and current values; and 4) calculating the angle and magnitude of the impedance. The contributions of this paper are the use of the d-q transformation to attain the battery impedance, theta, and its ripple power, as well as providing a controller design procedure which has impedance measurement capability. The online impedance information can be utilized for diverse applications such as the following: 1) a theta control for sinusoidal current charging; 2) the quantifying of reactive current and voltage; 3) ascertaining the state of charge; 4) determining the state of health; and 5) finding the optimized charging current. Therefore, the benefit of this method is that it can be deployed in already existing high-power chargers regardless of battery chemistry. Validations of the proposed approach were made by comparing measurement values by using a battery charger and a commercial frequency response analyzer.</P>

임피던스 기반 저비용 구조물 건전성 모니터링 기법

이종원(Jong-Won Lee) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.12

본 연구에서는 임피던스(impedance)를 이용하여 저비용으로 구조물의 결함을 탐지할 수 있는 기법을 연구한다. 임피던스 기법은 구조물 건전성 모니터링을 위한 국부적 결함탐지의 대표적인 기법으로써, 압전재료를 구조물의 표면에 부착하여 구조물의 전기-역학적 어드미턴스(electro-mechanical admittance) 신호를 모니터링 함으로써 결함을 추정하는 기법이다. 이 기법을 적용하기 위하여 일반적으로 고가의 임피던스 분석기(impedance analyser)가 사용되는데, 기술의 효과적인 보급을 위해서는 저비용의 기법을 개발할 필요가 있다. 본 연구에서는 임피던스 분석기를 대체하여, 일반적으로 실험실에서 사용되는 함수발생기(function generator)와 디지털 멀티미터(digital multimeter)만을 이용하여 전달 임피던스(transfer impedance)를 측정함으로써 구조물에 발생하는 결함을 탐지할 수 있는 기법을 연구한다. 즉, 건전상태와 손상상태에서 측정되는 전압의 진폭비를 이용한 손상지수를 비교함으로써 결함 유무를 판정할 수 있는 기법을 연구한다. 강재 시편에 대한 전달 임피던스 실험을 수행하였는데, 출력 전압의 진폭비를 이용한 손상지수를 비교함으로써 결함 유무를 합리적으로 판정할 수 있었다. 본 연구는 임피던스 기반 저비용 결함탐지기법을 위한 기초연구로써, 향후 결함의 위치 및 정도를 판정할 수 있는 연구가 보완된다면 구조물 건전성 모니터링에 효과적으로 활용될 수 있을 것으로 판단된다. This paper presents a method for detecting damage to a structure at low cost using its impedance. The impedance technique is a typical method to detect local damage for structural health monitoring. This is a common technique for estimating damage by monitoring the electro-mechanical admittance signal of the structure. To apply this technique, an expensive impedance analyzer is generally used. On the other hand, it is necessary to develop a low-cost variant to effectively disseminate the technique. In this study, a method based on the transfer impedance using a function generator and digital multimeter, which are generally used in the laboratory instead of an impedance analyzer, was developed. That is, this technique estimates the damage by comparing the damage index using the amplitude ratio of the output voltage measured in the healthy and damaged state. A transfer impedance test was carried out on a steel specimen. By comparing the damage index, the presence of damage could be assessed reasonably. This study is a basic investigation of an impedance-based low-cost damage detection method that can be used effectively for structural health monitoring if supplemented with future research to estimate the damage location and severity.

Impedance-based damage monitoring of steel column connection: numerical simulation

Ho, Duc-Duy,Ngo, Thanh-Mong,Kim, Jeong-Tae Techno-Press 2014 Structural monitoring and maintenance Vol.1 No.3

This study has been motivated to evaluate the practicality of numerical simulation of impedance monitoring for damage detection in steel column connection. In order to achieve the objective, the following approaches are implemented. Firstly, the theory of electro-mechanical (E/M) impedance responses and impedance-based damage monitoring method are outlined. Secondly, the feasibility of numerical simulation of impedance monitoring is verified for several pre-published experimental examples on steel beams, cracked aluminum beams, and aluminum round plates. Undamaged and damaged steel and aluminum beams are simulated to compare to experimental impedance responses. An aluminum round plate with PZT patch in center is simulated to investigate sensitive range of impedance responses. Finally, numerical simulation of the impedance-based damage monitoring is performed for a steel column connection in which connection bolts are damaged. From the numerical simulation test, the applicability of the impedance-based monitoring to the target steel column connection can be evaluated.

Calculation of the Reactor Impedance for Capacitively Coupled Plasma Sources

김용일,윤남식 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.5

The reactor impedance is calculated for capacitively coupled plasma sources, which one important sources for plasma processing. To the calculate reactor impedance, we calculate the axial profile of the electric field from a one-dimensional fluid simulation. The electromagnetic (EM) fields for the radial profile are expanded in a power series in !r/c from Maxwell’s equations and are then iteratively solved until a self-consistent steady state is obtained. Here, ! is the frequency of the applied RF wave, r is the radial position, and c is the speed of light. Using the resulting EM fields, we calculate the reactor impedance by using the field definition of impedance. We carried out a parametric study and investigated the effects on harmonics produced by a nonlinear RF sheath. In addition, we obtained the self-LC resonance conditions for various parameters. The reactor impedance is calculated for capacitively coupled plasma sources, which one important sources for plasma processing. To the calculate reactor impedance, we calculate the axial profile of the electric field from a one-dimensional fluid simulation. The electromagnetic (EM) fields for the radial profile are expanded in a power series in !r/c from Maxwell’s equations and are then iteratively solved until a self-consistent steady state is obtained. Here, ! is the frequency of the applied RF wave, r is the radial position, and c is the speed of light. Using the resulting EM fields, we calculate the reactor impedance by using the field definition of impedance. We carried out a parametric study and investigated the effects on harmonics produced by a nonlinear RF sheath. In addition, we obtained the self-LC resonance conditions for various parameters.

Yield of Combined Impedance-pH Monitoring for Refractory Reflux Symptoms in Clinical Practice

( Georgios Karamanolis ),( Georgios Kotsalidis ),( Konstantinos Triantafyllou ),( Dimitrios Polymeros ),( Asimina Gaglia ),( Smaragdi Fessatou ),( Maria Triantafyllou ),( Ioannis Papanikolaou ),( Spir 대한소화기기능성질환·운동학회(구 대한소화관운동학회) 2011 Journal of Neurogastroenterology and Motility (JNM Vol.17 No.2

Background/Aims In patients with gastroesophageal reflux disease, persistent symptoms on proton pump inhibitor (PPI) therapy may be due to residual acid or non-acid reflux. Combined impedance-pH has been suggested to be superior to pH alone in the management of refractory patients to PPI. The utility of implementation of this technique in every day clinical practice is still unknown. The aim of this study was to investigate the outcomes of patients studied with combined impedance-pH and to evaluate the yield of additional impedance monitoring over pH alone in patients with persistent gastroesophageal reflux disease symptoms. Methods Seventy-one patients (31 men; mean age, 49.1 ± 15.5 years) on PPI therapy underwent combined impedance-pH for persistent typical (76%) or atypical (49%) symptoms. Results During impedance-pH study, 44 (62%) patients reported symptoms. A positive symptom index (SI) was found in 21 (48%) patients: 8 (18.2%) had a positive SI for acid reflux, 9 (20.5%) for non-acid reflux and 4 (9.1%) for mixed reflux. Addition of impedance allowed association between reflux and symptoms in 20.5% of patients who would have been missed by pH study alone. Heartburn was the most prevalent symptom associated with acid reflux, whereas regurgitation and ear, nose and throat symptoms were associated with non-acid reflux. Conclusions The use of combined impedance-pH monitoring substantially increased the diagnostic yield compared to pH alone. With SI analysis, 20.5% of patients received a diagnosis that could not have been achieved with pH testing alone. (J Neurogastroenterol Motil 2011;17:158-163)

Electrical impedance-based crack detection of SFRC under varying environmental conditions

Kang, Man-Sung,An, Yun-Kyu,Kim, Dong-Joo Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.22 No.1

This study presents early crack detection of steel fiber-reinforced concrete (SFRC) under varying temperature and humidity conditions using an instantaneous electrical impedance acquisition system. SFRC has the self-sensing capability of electrical impedance without sensor installation thanks to the conductivity of embedded steel fibers, making it possible to effectively monitor cracks initiated in SFRC. However, the electrical impedance is often sensitively changed by environmental effects such as temperature and humidity variations. Thus, the extraction of only crack-induced feature from the measured impedance responses is a crucial issue for the purpose of structural health monitoring. In this study, the instantaneous electrical impedance acquisition system incorporated with SFRC is developed. Then, temperature, humidity and crack initiation effects on the impedance responses are experimentally investigated. Based on the impedance signal pattern observation, it is turned out that the temperature effect is more predominant than the crack initiation and humidity effects. Various crack steps are generated through bending tests, and the corresponding impedance damage indices are extracted by compensating the dominant temperature effect. The test results reveal that propagated cracks as well as early cracks are successfully detected under temperature and humidity variations.

Electrical impedance-based crack detection of SFRC under varying environmental conditions

Man-Sung Kang,Yun-Kyu An,Dong-Joo Kim 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.1

This study presents early crack detection of steel fiber-reinforced concrete (SFRC) under varying temperature and humidity conditions using an instantaneous electrical impedance acquisition system. SFRC has the self-sensing capability of electrical impedance without sensor installation thanks to the conductivity of embedded steel fibers, making it possible to effectively monitor cracks initiated in SFRC. However, the electrical impedance is often sensitively changed by environmental effects such as temperature and humidity variations. Thus, the extraction of only crack-induced feature from the measured impedance responses is a crucial issue for the purpose of structural health monitoring. In this study, the instantaneous electrical impedance acquisition system incorporated with SFRC is developed. Then, temperature, humidity and crack initiation effects on the impedance responses are experimentally investigated. Based on the impedance signal pattern observation, it is turned out that the temperature effect is more predominant than the crack initiation and humidity effects. Various crack steps are generated through bending tests, and the corresponding impedance damage indices are extracted by compensating the dominant temperature effect. The test results reveal that propagated cracks as well as early cracks are successfully detected under temperature and humidity variations.