• 한국안전학회지
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• 제16권1호
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• pp.37-42
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• 2001

The severity of electric shock is entirely dependent on body resistance. When the human body becomes a part of electric circuit, the body resistance is given as a function of shock scenario. Factors which consist of applied voltage, shock duration, body current path and contact area, etc.. The body resistance is defined as the voltage applied to subjects divided by the body current. To secure safety of the subjects, the experiment is conducted on 10 subjects, the body current is limited to 4mA. And only three factors under many shock scenario conditions are used to determine the body resistance. The three factors are the applied voltage, the current pathway and the contact area. The object of this work is to estimate the dynamic resistance of the human body as a function of applied voltage using the body current at low-voltage levels. The data of the body current at low-voltage levels are extrapolated to high-voltage levels using two analytic functions with specified constants calculated by numerical method. Also we can provide permissible body voltage for various copper electrodes on the basis of the data determined with the dynamic resistance and the body current.

• 대한한의학회지
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• 제24권1호
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• pp.100-109
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• 2003

Objectives : The purpose of this study is to 1. measure the skin resistance of jeong-acupuncture points using compound electrode, and 2. develop a database of skin resistance based on age and gender. Methods : The skin resistance of jeong-acupuncture points on the hands and feet of 191 healthy volunteers was measured using a specially designed compound electrode. A constant current of $5{\mu\textrm{A}}$ was applied to the measurement points and the skin resistance was obtained using amplifier, A/D converter and Acknowledge software program, Results : 1. ANOVA statistical analysis showed no significant differences between jeong-acupuncture points on hands and feet. 2. Paired samples t-test showed no significant differences between Yin-Yang meridian points, 3. When the data were sorted by gender, factor analysis showed statistically significant differences between male and female groups in all measured points except for left foot. 4. Based on the factor analysis, a significant relationship between the skin resistance and age was found in feet. However, no such relationship was found in hands. Conclusions : There are differences in skin resistance according to sex and age, Further clinical research is necessary using compound electrode method.

• International Journal of Automotive Technology
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• 제8권2호
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• pp.249-258
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• 2007

This paper proposes a method that can be used for the resistance estimation of a PWM (Pulse Width Modulation)-driven solenoid. By using estimated solenoid resistance, the PWM duty ratio was compensated to be proportional to the solenoid current. The proposed method was developed for use with EHB (Electro-Hydraulic Braking) systems, which are essential features of the regenerative braking system of many electric vehicles. Because the HU (Hydraulic Unit) of most EHB systems performs not only ABS/TCS/ESP (Electronic Stability Program) functions but also service braking function, the possible duration of continuous solenoid driving is so long that the generated heat can drastically change the level of solenoid resistance. The current model of the PWM-driven solenoid is further developed in this paper; from this a new resistance equation is derived. This resistance equation is solved by using an iterative method known as the FPT (fixed point theorem). Furthermore, by taking the average of the resistance estimates, it was possible to successfully eliminate the effect of measurement noise factors. Simulation results showed that the proposed method contained a sufficient pass-band in the frequency response. Experimental results also showed that adaptive solenoid driving which incorporates resistance estimations is able to maintain a linear relationship between the PWM duty ratio and the solenoid current in spite of a wide variety of ambient temperatures and continuous driving.

• 한국도로학회논문집
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• 제15권6호
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• pp.25-32
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• 2013

PURPOSES : The purpose of this study is to provide the method of how to measure the coefficient of thermal expansion of concrete using temperature compensation principle of electrical resistance strain gauge. METHODS : The gauge factor compensation method and thermal output(temperature-induced apparent strain) correction method of self-temperature compensation gauge were investigated. From the literature review, coefficient of thermal expansion measurement method based on the thermal output differential comparison between reference material(invar) and unknown material(concrete) was suggested. RESULTS : Thermal output is caused by two reasons; first the electrical resistivity of the grid conductor is changed by temperature variation and the second contribution is due to the differential thermal expansion between gauge and the test material. Invar was selected as a reference material and it's coefficient of thermal expansion was measured as $2.12{\times}10^{-6}m/m/^{\circ}C$. by KS M ISO 11359-2. The reliability of the suggested measurement method was evaluated by the thermal output measurement of invar and mild steel. Finally coefficient of thermal expansion of concrete material for pavement was successfully measured as $15.45{\times}10^{-6}m/m/^{\circ}C$. CONCLUSIONS : The coefficient of thermal expansion measurement method using thermal output differential between invar and unknown concrete material was evaluated by theoretical and experimental aspects. Based on the test results, the proposed method is considered to be reasonable to apply for coefficient of thermal expansion measurement.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.122.2-122.2
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• 2010

Knowledge of ground thermal properties is most important for the proper design of BHE(borehole heat exchanger) systems. The configure type, pipe size and thermal performance of the BHE is highly dependent on the ground source heatpump system-efficiency and instruction cost. Thermal response tests with mobile measurement devices were developed primarily for in-situ determination of design data for Standing Column Well apply. The main purpose has been to determine in-situ values of effective ground thermal conductivity and thermal resistance, including the effect of ground-water flow and natural convection in the boreholes. The test rig is set up on a some trailer, and contains a sub-circulation pump, a boiler, temperature sensors, flow meter and a data logger for recording the temperature and circulation fluid flow data. A constant heating power is injected into the SCW through the test rig and the resulting temperature change in the SCW is recorded. The recorded temperature data are analysed with a line-source model, which gives the effective in-situ values of rock thermal conductivity and thermal resistance of SCW.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1998년도 추계학술대회논문집:21세기에 대비한 지능형 통합항만관리
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• pp.183-188
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• 1998

A quartz crystal analyzer is utilized to monitor the cmsion process of an aluminum surface of a quartz crystal by sea water. A quartz crystal having 2000${\AA}$ of aluminum layer is installed in a spedally designed cell and is in contact with an electrolyte solution. While a constant potential is applied to the cell, the resonant frequency and resonant resistance are simultaneously measured using the quartz crystal analyzer. In addition, surface topographs are taken with an atomic force microscope(AFM) and the element analysis of the surface is conducted using an energy dispersive X-ray spectrornetedEDX). The simultaneous measurement of resonant frequency and resonant resistance during the corrosion process explains the change of surface structure caused by the corrosion. The variation of resonant frequency addresses the amount surface metal dissolution. As a conclusion, it is found that a simple measurement using the quartz crystal analyzer can replace the complex monitoring employing large equipments in the investigation of a corrosion process of metal surface.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.581-586
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• 2009

Knowledge of ground thermal properties is most important for the proper design of large scale BHE(borehole heat exchanger) systems. The type, pipe size and thermal performance of the BHE is highly dependent on the ground source heatpump system-efficiency and instruction cost. Thermal response tests with mobile measurement devices were developed primarily for insitu determination of design data for large diameter BHE for triple-U spacer apply. The main purpose has been to determine insitu values of effective ground thermal conductivity and thermal resistance, including the effect of ground-water flow and natural convection in the boreholes. The test rig is set up on a some trailer, and contains a circulation pump, a inline heater, temperature sensors, flow meter, power analysis meter and a data logger for recording the temperature, fluid flow data. A constant heat power is injected into the borehole through the tripl-U pipes system of test rig and the resulting temperature change in the borehole is recorded. The recorded temperature data are analysed with a line-source model, which gives the effective insitu values of rock thermal conductivity and borehole thermal resistance of large diameter BHE for spacer apply.

• 한국환경복원기술학회지
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• 제8권1호
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• pp.100-107
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• 2005

As a result of this study, vitality of natural monuments (large trees) looks relatively good but they require continuous management. Also, the management for condition recovery and condition maintenance, and minimum measures are needed at least to avoid natural calamity. Major points induced are as follows : The first, although most of natural monument large trees showed favorable growth environment, most of them are aged and have dense twigs with requirement for weed trimming to remove complicated and unnecessary branches. In addition, as most of large trees grow alone in a large space with potential natural calamity, thus, minimum measures are required at least. Secondly, change in electric resistance in surveyed large trees was relatively favorable, however, large trees with soil covering showed high electric resistance and were found to have low vitality. As shown, this study was conducted to find out the measurement techniques of natural monuments, Basic foundation is suggested through the measurement of electric resistance, and the vitality of natural monuments; more accurate investigation will be remained for further discussion.

• 한국전기전자재료학회논문지
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• 제19권9호
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• pp.825-831
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• 2006

As an increase of chip complexity and level of chip integration, chip input/output (I/O) pad pitches are also drastically reduced. With arrival of high complexity SoC (System on Chip) and SiP (System in Package) products, conventional horizontal type probe card showed its limitation on probing density for wafer level test. To enhance probing density, we proposed new vertical type probe card that has the $70{\mu}m$ probe needle with tungsten wire in $80{\mu}m$ micro-drilled hole in ceramic board. To minimize alignment error, micro-drilling conditions are optimized and epoxy-hardening conditions are also optimized to minimize planarity changes. To apply wafer level test for target devices (T5365 256M SDRAM), designed probe card was characterized by probe needle tension for test, contact resistance measurement, leakage current measurement and the planarity test. Compare to conventional probe card with minimum pitch of $50{\sim}125{\mu}m\;and\;2\;{\Omega}$ of average contact resistance, designed probe card showed only $22{\mu}$ of minimum pitch and $1.5{\Omega}$ of average contact resistance. And also, with the nature of vertical probing style, it showed comparably small contact scratch and it can be applied to bumping type chip test.

• 전자공학회논문지A
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• 제31A권8호
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• pp.46-52
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• 1994

DC and AC current crowding effects for microwave and high speed bipolar transistors are investigated in detail using a new and accurate measurement technique based on Z-parameter equationa. Using the new measurement technique dc and ac current crowding effects have been explained clearly in bipolar junction transistors. To model ac crowding effects a capacitive element defined as base capacitance (C$_b$), called ac crowding capacitance is added to base resistance in parallel thereby treating the base resistance(R$_b$) as base impedance Z$_b$. It is shown that base resistance decreases with increasing collector current due to dc current crowding and approaches to a certain limited value at high collector current due to current crowding and approaches to a certain limited value at high collector currents regardless of the emitter size. It is also observed that due to ac current crowding base capacitance increases with increasing collector current. To quantigy the ac crowding effects for SPICE circuit simulation the base capacitance(C$_b$) including the base depletion and diffusion components has been modeled with an analytical expression form.