• Journal of Environmental Health Sciences
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• v.35 no.6
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• pp.461-467
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• 2009

Exposure analysis is a critical component of determining the health impact of pollutants. Global positioning systems (GPS) could be useful in developing time-location information for use in exposure analysis. This study compares four low cost GPS receivers with data logging capability (Garmin 60, Garmin Forerunner 201, GeoStats GeoLogger and Skytrx minitracker MT4100) in terms of accuracy, precision, and ease of use. The accuracy of the devices was determined at two known National Geodetic Survey points. The coordinates logged by the devices were compared when the devices were carried while walking and driving. The Garmin 60 showed better accuracy and precision than the GeoLogger when they were placed at the geodetic points. The Forerunner and Skytrx did not record when they were kept stationary. When the subject wore the devices while walking, the location of the devices differed by about 8 m on average between any two device combinations involving the four devices. The distance between the coordinates logged by the devices decreased when the devices were carried with their antennas facing the sky. All the devices showed similar routes when they were used in a car. All the devices except the Forerunner had satisfactory signal reception when they were worn and when they were carried in the car. The GeoLogger is less comfortable for the subject because of specific wearing requirements. This evaluation found that the Garmin 60 and the Skytrx may be useful in personal exposure analysis studies to record time-location data.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.3
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• pp.105-113
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• 2007

This study was conducted to analyze the effects of environmental factors such as soil moisture, light intensity, temperature and humidity on changes in cambial electrical resistance. To improve data quality, cambial electrical resistance was continuously measured at fixed points by using a data logger isolated from alternating current. The relationship between environmental factors and changes in cambial electrical resistance was also analyzed. The results are as follows: 1. Cambial electrical resistance is highly correlated to the temperature of the measured area(r=-0.934). Therefore, temperature compensation is needed to analyze the effects of other environmental factors on cambial electrical resistance changes. 2. If temperature is compensated for, the change of cambial electrical resistance is highly correlated to water vapor pressure(r=-0.836). 3. If temperature and humidity are compensated for, the change of cambial electrical resistance is highly correlated to intensity of light(r=-0.738). 4. Diurnal deviation of soil water potential is not more significantly related than the change of cambial electrical resistance. However, in the long-term, soil water potential and cambial electrical resistance are highly correlated(r=-0.831). This indicates that soil moisture significantly influences the long-term change of cambial electrical resistance.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.375-383
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• 2011

This paper describes a real-time hardware simulator for a grid-tied Permanent Magnet Synchronous Generator (PMSG) wind power system, which consists of an anemometer, a data logger, a motor-generator set with vector drive, and a back-to-back power converter with a digital signal processor (DSP) controller. The anemometer measures real wind speed, and the data is sent to the data logger to calculate the turbine torque. The calculated torque is sent to the vector drive for the induction motor after it is scaled down to the rated simulator power. The motor generates the mechanical power for the PMSG, and the generated electrical power is connected to the grid through a back-to-back converter. The generator-side converter in a back-to-back converter operates in current control mode to track the maximum power point at the given wind speed. The grid-side converter operates to control the direct current link voltage and to correct the power factor. The developed simulator can be used to analyze various mechanical and electrical characteristics of a grid-tied PMSG wind power system. It can also be utilized to educate students or engineers on the operation of grid-tied PMSG wind power system.

• Wind and Structures
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• v.14 no.4
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• pp.337-357
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• 2011

The collection of wind speed time series by means of digital data loggers occurs in many domains, including civil engineering, environmental sciences and wind turbine technology. Since averaging intervals are often significantly larger than typical system time scales, the information lost has to be recovered in order to reconstruct the true dynamics of the system. In the present work we present a simple algorithm capable of generating a real-time wind speed time series from data logger records containing the average, maximum, and minimum values of the wind speed in a fixed interval, as well as the standard deviation. The signal is generated from a generalized random Fourier series. The spectrum can be matched to any desired theoretical or measured frequency distribution. Extreme values are specified through a postprocessing step based on the concept of constrained simulation. Applications of the algorithm to 10-min wind speed records logged at a test site at 60 m height above the ground show that the recorded 10-min values can be reproduced by the simulated time series to a high degree of accuracy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1311-1312
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• 2010

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.34-41
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• 2006

A 3-dimensional stress measurement system based on the bore hole bottom deformation method, which is one of the stress relief methods, was developed. A pilot bore hole is drilled from the bottom of a bore hole and the stress meter is inserted into the pilot bore hole in the method. The bore hole is advanced as an over coring and the deformations in seven directions are measured by cantilever type-sensors. Using the cantilever type-sensors saves time for hardening of glue. No cable connection between the stress meter and a data logger is necessary since a compact data logger is installed in the stress meter. The accuracy of the stress meter was confirmed by a biaxial test for a Shikotsu welded tuff block although in-situ tests have not been carried out yet.

• Journal of the Korean Society of Physical Medicine
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• v.4 no.2
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• pp.117-124
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• 2009

Purpose：The purpose of this study was to investigate of the change of the forward head posture(FHP) according to computer using time. Methods：Subjects were 30 male and 30 female. The factors of FHP were measured cranial vertical angle, cranial rotation angle, and head, upper back, neck flexion/extension angle according to computer using time. Change of FHP used to Digital Inclinometry(JTech, Dualer IQTM Dual Inclinometer). The data were collected by data logger(Logger Teknologi HB, Akarp, Sweden). Results：Cranial vertical angle, cranial rotation angle, and head, upper back, neck flexion/extension were increased according to computer using time(p<.05). But cranial vertical angle and cranial rotation angle, and head, upper back, neck flexion/extension were not significant differences between male and female group(p>.05). Conclusion：The effects of cranial vertical angle, cranial rotation angl and head, neck and upper back angle depend on the computer task time. Increased of FHP may result increased tension in posture muscles of cervical spine, resulting in a risk of musculoskeletal disorders.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.2
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• pp.141-152
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• 2022

As a method to understand the ecological habits around the artificial reef, various reports such as fishing gear survey, diving, sound survey, underwater CCTV and camera, etc. are reported. Among them, the sound survey method is carried out by installing an acoustic system on the ship and can be investigated regardless of the marine environment such as time constraints and turbidity. Such method, however, takes a lot of manpower and time as the ship travels at a constant speed. Investigations around artificial reefs are being conducted in an artificial way, and a lot of time and labor are consumed as such. Maritime buoys have been operated for various purposes such as route signs, weather observation, marine environment monitoring and defense monitoring for navigation safety in the past, but studies on monitoring systems for ecological habits and distribution of fish using marine buoys are remarkably insufficient. Therefore, this study aims to develop a system that allows users to directly monitor fish group detector data by estimating the distribution of fish groups around artificial reefs and using wireless communication at sea. In order to confirm the suitability of the maritime buoy used in this study, it was operated to compare data using LTE-equipped buoys capable of wireless communication and a data logger-type system buoy. Data transmission of buoys capable of LTE communication was carried out in a 10-minute ON, 10-minute OFF method due to the limitation of the power supply capacity, and data of the data logger-type buoy received full data. We compared and analyzed the data received from the two fish detectors. It is expected that real-time monitoring of the wireless buoy detection device using LTE will be possible through future research.

• The Journal of the Acoustical Society of Korea
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• v.25 no.4
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• pp.178-183
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• 2006

A hydrophone away is used to measure spatial distribution in underwater sound field and to detect incoming direction of sound waves in the ocean. It is not usually convenient to handle the hydrophone away because of its extensive scale. And it is not easy to purchase the hydrophone away because of expensive price. A hydrophone logger combined with a hydrophone and data logger was developed to consist conveniently of a hydrophone away for use to receive underwater sound waves. And a hydrophone array system with the hydrophone loggers was developed. Main configurations of the hydrophone 1o99er and the hydrophone array system are introduced in this paper. Also we present some measurement results by the hydrophone logger in a water tank and measurement examples on ambient noise in the sea by the hydrophone away system. And we discuss some advantages in use of the hydrophone array system.

• Journal of Korean Society of Rural Planning
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• v.21 no.4
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• pp.177-186
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• 2015

The main objective of this study was to assess the applicability of IoT (Internet of Things)-based flood management under climate change by developing intelligent water level monitoring platform based on IoT. In this study, Arduino Uno was selected as the development board, which is an open-source electronic platform. Arduino Uno was designed to connect the ultrasonic sensor, temperature sensor, and data logger shield for implementing IoT. Arduino IDE (Integrated Development Environment) was selected as the Arduino software and used to develop the intelligent algorithm to measure and calibrate the real-time water level automatically. The intelligent water level monitoring platform consists of water level measurement, temperature calibration, data calibration, stage-discharge relationship, and data logger algorithms. Water level measurement and temperature calibration algorithm corrected the bias inherent in the ultrasonic sensor. Data calibration algorithm analyzed and corrected the outliers during the measurement process. The verification of the intelligent water level measurement algorithm was performed by comparing water levels using the tape and ultrasonic sensor, which was generated by measuring water levels at regular intervals up to the maximum level. The statistics of the slope of the regression line and $R^2$ were 1.00 and 0.99, respectively which were considered acceptable. The error was 0.0575 cm. The verification of data calibration algorithm was performed by analyzing water levels containing all error codes in a time series graph. The intelligent platform developed in this study may contribute to the public IoT service, which is applicable to intelligent flood management under climate change.