• 한국안전학회지
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• 제31권6호
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• pp.19-24
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• 2016

One of key parameters on lightning protection system design of electric, information and communication system is grounding impedance. Earth impedance includes numerous information about earthing performance of grounding system. This paper suggests grounding impedance measuring device which is comprised of wideband current source, voltage and current measuring components. We used IQ Demodulation to measure more accurate phase difference of voltage and current. The range of frequency is up to 1 MHz that is IEEE defined as the range of lightning surge. We compared developed grounding impedance measuring device with existing one to test its performance, and we used grounding system while we implemented measurement and analysing by using fall of potential method IEEE Std.81 proposed.

• 한국자동차공학회논문집
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• 제6권6호
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• pp.218-225
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• 1998

FTIR spectroscopy, useful technology for simultaneous and continuous measurement of the various components of the automotive exhaust gas, is utilized to investigate catalytic reaction charactristics of methane and a few unregulated exhaust emissions of NGV. Major findings are (1) catalytic reaction characteristics of methane measured in unsteady states of varying temperature are similar to those measured in steady states, (2) about 24 % of NO was oxidized to $NO_2$ as soon as they encounter catalysts, (3) study of formaldehyde suffers from difficulties in measurement due to the proximity in wavenumber of formaldehyde and methane, and requires an analyzer of higher resolution and accuracy than used in this study.

• 한국항행학회논문지
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• 제20권6호
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• pp.625-630
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• 2016

최근 다양한 형태의 영상 콘텐츠가 제작되고 있고, 이를 위한 저작권 보호기술에 대한 관심이 높아지고 있다. 본 논문에서는 컬러 영상을 위한 영상암호화 기술을 제안한다. 이 기술은 영상을 RGB 색차성분으로 분할한 후, 윤곽선을 기준으로 쿼드트리 분할을 수행한다. 쿼드트리 분할 후, 선정된 블록들을 대상으로 암호화를 수행한다. 색차성분을 대상으로 암호화를 수행하여 암호화 효율을 측정하고, 컬러 영상으로 재구성한 후에도 암호화 효율을 측정한다. 암호화 효율은 시각적인 측정방식과 객관적인 화질평가 방식을 이용한다. 실험결과 PSNR 수치는 색차성분의 경우 7~10[dB], 컬러 영상의 경우 16~19[dB]로 측정되었다. 본 논문에서 제안한 영상암호화 기술은 향후 다양한 디지털 영상 콘텐츠의 저작권 보호에 사용될 것으로 보인다.

• Wind and Structures
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• 제6권1호
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• pp.53-70
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• 2003

Tsing Ma Bridge in Hong Kong is the longest suspension bridge in the world carrying both highway and railway. It has two H-shape concrete towers, each of which is composed of two reinforced concrete legs and four deep transverse prestressed concrete beams. A series of wind tunnel tests have been performed to measure the aerodynamic coefficients of the tower legs and transverse beams in various arrangements. A 1:100 scaled 3D rigid model of the full bridge tower assembled from various tower components has been constructed for different test cases. The aerodynamic coefficients of the lower and upper segments of the windward and leeward tower legs and those of the transverse beams at different levels, with and without the dummy bridge deck model, were measured as a function of yaw wind angle. The effects of wind interference among the tower components and the influence of the bridge deck on the tower aerodynamic coefficients were also investigated. The results achieved can be used as the pertinent data for the comparison of the computed and field-measured fully coupled buffeting responses of the entire bridge under yaw winds.

• ETRI Journal
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• 제34권6호
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• pp.858-868
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• 2012

In this paper, stochastic models for the cross-correlation of multiple channels are established based on measurement data collected using a wideband multiple-input multiple-output relay Band Exploration and Channel Sounder system at 3.7 GHz. We propose models for the cross-correlation characteristics of large-scale parameters (LSPs) between two links, that is, the base station and mobile station (MS) link and the relay station and MS link. The LSPs include shadow fading, Rician K-factor, delay spread, angle spread of arrival, and angle spread of departure. Furthermore, models are established for the cross-correlation of the small-scale fading in the impulse responses of two links. The statistics of these model parameters are investigated as functions of geometrical features of the multilink. They are extracted from a large amount of cross-correlation observations, which are obtained in three measurement sites along more than one hundred measurement routes. These models can be used together with the standard single-link channel models for the generation of correlated components, for example, path clusters, in two separate channels.

• 한국정밀공학회지
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• 제12권7호
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• pp.46-52
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• 1995

This paper proposes methodologies for the development of radiation thermometer using InSb photo-detector of which spectral sensitivity is excellent over the wave length range of 2 .mu. m .approx. 5 .mu. m. The proposed radiation thermometer has broad measurement range from normal to high, up to more than 1000 .deg. C, with high accuracy, and can measure temperature on the material surface or heat emission noncontactely with high speed. Optical system was consisted of two convex lens with foruslength of 15.2mm for infrared lay focusing, Ge filter to cut the short wave length components and sapphire filter to cut the long wave length components. The cold shielded was installed in the whole surface of the light-absorbing element to remove the error- mometer, calibration using black body furnace which has temperature range of 90 .deg. C .approx. 1100 .deg. C was carried out, and temperature calaibration curve was obtained by exponential function curvefitting. The result shows maximum error less than 0.24%(640K .+-. 1.6K) over the measurement range of 90 .deg. C .approx. 700 .deg. C, and from this result the usefulness of the developed thermometer has been confirmed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권6호
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• pp.2463-2482
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• 2016

Cloud services are often provisioned to their customers using user-friendly web browsers with flexible and rich plug-in environments. Delay is one of the fundamental performance metrics of these web-based services. Commonly-used network measurement tools usually only measure network delay and it may be difficult to infer the web-delay performance using only network layer measurement approaches. In this paper, we propose to evaluate the application layer delay in a browser-based network measurement platform using engineered scripts. We conducted a delay measurement study using instrumented scripts in the proposed browser-based measurement platform. Our investigation included a comparison study of three browser-scripting delay measurement methods, including Java applet, JSP and Flash ActionScript. We developed a browser-based delay measurement testbed over the Internet so that different delay measurement tools could be evaluated in the same real network environment including typical Internet paths and the Baidu cloud. We also decomposed the components of the end-to-end delay process of the above measurements to reveal the difference and relationship between the network-layer delay and the application-layer delay. Our measurement results characterize the stochastic properties of the application-layer delay over real Internet paths, and how these properties vary from the underlying network layer delay. This browser-scripting measurement approach can be easily deployed on different cloud service platforms to inspect their application-layer delay performance between end clients and the cloud platforms. Our measurement results may provide insights into designing new cloud services with enhanced quality-of-experience perceived by cloud users.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.101-104
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• 2004

This paper addresses uncertainty issues encountered recently in measuring head vibration using the conventional 6-axis or 9-axis bite-bar Those conventional bite-bars are shown to present insufficient information to measure a complete 6 degree-of-freedom motion of head vibration. In order to overcome such limit, a theoretical measurement model that consists of four 3-axis linear accelerometers is suggested (Theoretical backgrounds presented in this paper shall have been addressed in the international congress of ICA 2004 in this April). It is shown to enable the direct measurement of three angular acceleration components and six angular velocity-dependent nonlinear terms. In audition to the three linear acceleration terms, those nine angular motion-dependent ones are found to make it possible to evaluate the general head vibration for a given position. To examine the feasibility of the proposed method, a newly designed 12-axis bite-bar was developed. Detailed experimental results obtained using the developed 12-axis bite-bar are illustrated in the presentation of this paper, which illustrates what amount of measurement accuracy provides. But, this paper provides more detailed experimental data and extended uncertainty factors.

• Journal of Power Electronics
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• 제10권6호
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• pp.611-620
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• 2010

This paper presents a new architecture, called "Power Electronics Remote Wiring and Measurement Laboratory (PermLAB)", that translates a common gateway interface (CGI) string from a remote web user to a web server connected to a 3-dimension switching matrix board, can be used to switch on and off, and to control a cluster of instruments and components. PermLAB addresses real-time connection, switching, and data acquisition over the Internet instead of using simulated data. A software procedure uses a signature system to identify each instrument and component in a complex system. The Web-server application is developed in HTML, JavaScript and Java, and in C language for the CGI interface, which resides in a controller portion of LabVIEW. The LabVIEW software fully integrates the Web sever, LabVIEW data acquisition boards and controllers, and the 3-dimensional switching matrix board. The paper will analyze a half-wave rectifier (AC - DC converter) circuit connected over the Internet using the PermLAB. PermLAB allows students to obtain real data by real-time wiring of real circuits in the laboratory using a "virtual breadboard" on the Web. The software for the Web-based 3-dimensional system is flexible, portable, can be integrated into many laboratory applications or expanded, and easily accessible worldwide.

• 대한임베디드공학회논문지
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• 제18권6호
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• pp.277-283
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• 2023

Vital signals provide essential information regarding the health status of individuals, thereby contributing to health management and medical research. Present monitoring methods, such as ECGs (Electrocardiograms) and smartwatches, demand proximity and fixed postures, which limit their applicability. To address this, Non-contact vital signal measurement methods, such as CW (Continuous-Wave) radar, have emerged as a solution. However, unwanted signal components and a stepwise processing approach lead to errors and limitations in heart rate detection. To overcome these issues, this study introduces an integrated neural network approach that combines noise removal, demodulation, and dominant-frequency detection into a unified process. The neural network employed for signal processing in this research adopts a MLP (Multi-Layer Perceptron) architecture, which analyzes the in-phase and quadrature signals collected within a specified time window, using two distinct input layers. The training of the neural network utilizes CW radar signals and reference heart rates obtained from the ECG. In the experimental evaluation, networks trained on different datasets were compared, and their performance was assessed based on loss and frequency accuracy. The proposed methodology exhibits substantial potential for achieving precise vital signals through non-contact measurements, effectively mitigating the limitations of existing methodologies.