• 디지털산업정보학회논문지
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• 제11권4호
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• pp.189-202
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• 2015

This paper is focused on the investigation of the negative factors from smart-phone as internal affecting the use of smartphone and found their relationship. For the validation of this study model, 300 university students randomly selected in Seoul and Gyeongnam province. The measurement model was evaluated by using SPSS 18.0, and the evaluated result was summarized as follows. First, it was found that the techno-stress of smartphone user significantly associated with the fun and pleasure felt from using smatphone. It was assumed that a higher techno-stress negatively affects fun and pleasure from using smartphone. Second, the techno-stress of smartphone users was found to affect smartphone addiction. This means that more techno-stress users feel as they use smartphone, the more tendency to smartphone addiction. Third, flow was significantly associated with the smartphone addiction. Forth, Flow was significantly associated with satisfaction of the smartphones use. Fifth, it was indicated that when users had more flow and addiction from using smartphone, their satisfaction level was also higher.

• 한국안전학회지
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• 제28권1호
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• pp.24-28
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• 2013

This article evaluates the accuracy of noise measurements for 37 noise measurement applications for iPhone 4 and iPhone 3Gs. Noise levels were measured using simultaneously a precision sound level meter and iPhones installed noise measurement applications at the levels of 70 dB, 80 dB and 90 dB at 1,000 Hz. Measurement errors were estimated by subtracting two measurements between iPhone and sound level meter. It was found that measurement errors of 34 applications(89.2%) were greater than ${\pm}2$ dB which is the maximum allowable error range for the Type II sound level meter. It was only 4 applications that measurement errors lie within ${\pm}2$ dB error range. There was no significant differences among measurements with four iPhone 4s. However, there were significant differences between the measurements with iPhone 4 and iPhone 3Gs using the same application. It was due to the different hardware specifications such as microphone. Therefore, noise measurement applications, for example, which has to utilize hardware of the smartphone, should be programmed to identify hardware specifications and to adopt appropriate correction factors upon hardware specifications. In conclusion, it is necessary to check accuracy and validity before using the noise measurement applications for iPhones. Also, it was suggested that it should develop an evaluation guideline or protocol on accuracy testing for the measurement applications using a smartphone.

• 한국산림과학회지
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• 제110권1호
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• pp.72-81
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• 2021

본 연구는 다양한 임목 정보를 측정하고 효과적으로 관리하기 위해 스마트폰 애플리케이션과 웹 애플리케이션 서버(Web Application Server, WAS)를 개발하였다. 수고, 방위, 고도, 경사, 위치 좌표는 스마트폰에 내장된 동작센서를 통해 취득된 각도를 삼각법에 적용하여 측정하였으며, 흉고직경 및 거리는 Google AR Core에서 제공하는 AR API(Application Programming Interface)를 응용하여 측정할 수 있도록 하였다. 웹 애플리케이션 서버는 스마트폰이 측정한 데이터를 수신하여 저장, 조회, 출력하고 수목의 위치를 카카오 맵에 표시할 수 있도록 개발하였다. 또한, 개발된 애플리케이션의 정확성을 평가하기 위해 인공 침엽수림에서 잣나무 90본, 천연 혼효림에서 무작위로 90본을 선정하여 버텍스 및 윤척과 비교하였다. 비교 결과, 흉고직경과 수고 모두 95% 수준에서 유의한 결과를 나타내었으며, 흉고직경의 경우 인공 침엽수림이 평균 0.6745 cm, 천연 혼효림에서는 평균 1.0139 cm의 오차를 보였다. 수고는 인공 침엽수림이 평균 0.6714 cm, 천연 혼효림은 평균 1.3297 m의 오차를 보였다.

• 대한임베디드공학회논문지
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• 제9권6호
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• pp.323-334
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• 2014

In this paper, we proposed indoor positioning system with improved accuracy. The proposed indoor location measurement system is based pedestrian location measurement method that use the embedded sensor of smartphone. So, we do not need wireless external resources, such as GPS or WiFi signals. The conventional methods measure indoor location by generating a movement route of pedestrian by step and direction recognition. In this paper, to correct the direction sensor error, we use the common feature of the normal indoor floor map that the indoor path is lattice-structured. And we quantize moving directions depending on the direction of indoor path. In addition, we propose moving direction measuring method using geomagnetic sensor and gyro sensor to improve the accuracy. Also, the proposed step detection method uses angle and accelerometer sensors. The proposed step detection method is not affected by the posture of the smartphone. Direction errors caused by direction sensor error is corrected due to proposed moving direction measuring method. The proposed location error correction method corrects location error caused by step detection error without the need for external wireless signal resources.

• Structural Engineering and Mechanics
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• 제63권6호
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• pp.771-777
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• 2017

The applications of smartphones or other portable smart devices have dramatically changed people's lifestyle. Researchers have been investigating useage of smartphones for structural health monitoring, earthquake monitoring, vibration measurement and human posture recognition. Their results indicate a great potential of smartphones for measuring pedestrian-induced loads like walking, jumping and bouncing. Smartphone can catch the device's motion trail, which provides with a new method for pedestrain load measurement. Therefore, this study carried out a series of experiments to verify the application of the smartphone for measuring human-induced load. Shaking table tests were first conducted in order to compare the smartphones' measurements with the real input signals in both time and frequency domains. It is found that selected smartphones have a satisfied accuracy when measuring harmonic signals of low frequencies. Then, motion capture technology in conjunction with force plates were adopted in the second-stage experiment. The smartphone is used to record the acceleration of center-of-mass of a person. The human-induced loads are then reconstructed by a biomechanical model. Experimental results demonstrate that the loads measured by smartphone are good for bouncing and jumping, and reasonable for walking.

• Journal of the Optical Society of Korea
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• 제17권3호
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• pp.249-254
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• 2013

In ophthalmology, a pupillometer, a device to measure the diameter of the pupil of the eye, can provide information on the function of the autonomic nervous system. The current pupillometers on the market are either too large to be a handheld instrument, or relatively expensive. In this study, a pupillometer based on a smartphone was designed. Both white and infrared LEDs and a 3M pixel camera of a smartphone were applied for the visual stimuli to an eye and for the acquisition of the eye images, respectively. Contrary to the existing method of pupil measurement that usually observe the variation of pupil diameter, the proposed algorithm in this study was applied to calculate the constriction ratio of the pupillary area in response to pupillary light reflex. The results showed that the constriction ratio of the pupillary area were all in the normal range (above 4.0) from the sixteen healthy participants. It is believed that the approach to pupil measurement used in this study is suitable for a mobile interface, and this system can be applied to clinical research, home-use healthcare, and distributed to some areas which suffer from problems like a lack of medical support.

• Journal of Positioning, Navigation, and Timing
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• 제9권3호
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• pp.273-284
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• 2020

The performance of Global Navigation Satellite System (GNSS) chipset and Inertial Measurement Unit (IMU) sensors embedded in smartphones for location-based services (LBS) is limited due to the economic reasons for their mass production. Therefore, it is necessary to efficiently process the output data of the smartphone's embedded sensors in order to derive the optimum navigation values and, as a previous step, output performance of smartphone embedded sensors needs to be verified. This paper analyzes the navigation performance of such devices by processing the raw measurements data output from smartphones. For this, up-to-dated versions of smartphones provided by Samsung (Galaxy s10e) and Xiaomi (Mi 8) are used in the test experiment to compare their performances and characteristics. The GNSS and IMU data are extracted and saved by using an open market application software (Geo++ RINEX Logger & Mobile MATLAB), and then analyzed in post-processing manner. For GNSS chipset, data is extracted from static environments and verified the position, Carrier-to-Noise (C/N₀), Radio Frequency Interference (RFI) performance. For IMU sensor, the validity of navigation and various location-based-services is predicted by extracting, storing and analyzing data in static and dynamic environments.

• Journal of Radiation Protection and Research
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• 제42권4호
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• pp.205-211
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• 2017

Background: Radiation is used in a variety of areas, but it also poses potential risks. Although radiation is often used with great effectiveness in many applications, people perceive potential risks associated with radiation and feel anxious about the possibility of radiation exposure. Various methods of measuring radiation doses have been developed, but there is no way for the general public to measure their doses with ease. Currently, many people use smartphones, which provide information about the location of an individual phone through network connections. If a smartphone application could be developed for measuring radiation dosage, it would be a very effective way to measure individuals' radiation doses. Thus, we conducted a survey study to assess the social acceptance of such a technology by the general public and their intent to use that technology to measure radiation doses, as well as to investigate whether such an intention is correlated with anxiety and attitudes toward the use of radiation. Materials and Methods: A nationwide online survey was conducted among 355 Koreans who were 20 years old or older. Results and Discussion: Significant differences were found between the genders in attitudes, perceptions of radiation risk, and fears of exposure to radiation. However, a significant difference according to age was observed only in the intent to use a smartphone dose measurement application. Attitudes towards the use of radiation exerted a negative effect on radiation risk perception and exposure anxiety, whereas attitudes towards the use of radiation, risk perception, and anxiety about exposure were found to have a positive impact on the intent to use a smartphone application for dose measurements. Conclusion: A survey-based study was conducted to investigate how the general public perceives radiation and to examine the acceptability of a smartphone application as a personal dose monitoring device. If such an application is developed, it could be used not only to monitor an individual's dose, but also to contribute to radiation safety information infrastructure by mapping radiation in different areas, which could be utilized as a useful basis for radiation research.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.993-995
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• 2014

우리나라의 대표적인 주거형태는 공동주택이다. 이로 인해 생활 소음으로 인한 민원 발생이 급증하고 있는 상태이다. 이에 실생활에서 주변 소음으로 인해 고통을 받는 경우에는 소음 측정기로 측정하여 민원을 제기할 수도 있다. 그러나 일반 가정에서는 전문적인 장비를 동원해 소음 측정을 하기가 어렵기 때문에 간편하게 스마트폰 앱을 사용하는 경우가 많다. 기존에 출시된 소음 측정 앱은 스마트폰의 기종별로 센서의 감도가 달라 동일한 조건에서 측정하여도 값이 다르게 나오는 등 정확도가 현저히 떨어지며, 실제 소음 측정을 위한 목적으로 사용하기가 어렵다. 따라서 본 논문은 스마트폰을 이용한 생활 환경의 소음 측정을 위한 모바일 데이터 처리 시스템을 제안한다. 본 연구의 기대 효과는 소음 측정의 정밀도를 높이고 소음이 발생하는 위치를 검색하여 민원처리에 활용할 수 있다.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.231-234
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• 2013

According to the recent development of USN technology, it has been applied in various fields of construction management. In particular, the concrete curing management using the wireless measurement system is actively being conducted. However, the existing method has limitations such as the reinstallation of temperature sensors and repositioning of repeaters. It is also not easy to acquire the measured data. Thus, this study focuses on the concrete curing management. This study proposes data acquisition method using the smartphone on construction site and tests applicability of the data measuring device and the smartphone. The test allows us to suggest the actual communication distance on construction site and to determine the correction value that is applied to the measured temperature. The data acquisition method proposed in this study is intended to enable appropriate management on construction site and will be able to be applied effectively to a variable construction site. It can also be used in all fields of construction management.