• 산업기술연구
• /
• 제31권B호
• /
• pp.99-105
• /
• 2011

Recently, smartphones have been widely used in wireless communications which caused severe data overload in cellular networks. Cellular companies consider increasing wireless data capacity in overloaded areas. Determining overloaded areas is mainly made from user reports which are currently collected by calling or simple apps by some active users experiencing overloads. Since the current reporting method is inconvenient and does not contain detail information about the overload conditions, and therefore is used by only some active users, the overloaded areas determined from the reports are not likely to be accurate. Therefore, we need a new reporting method which is convenient enough for even inactive users to willingly report the overload condition and which delivers detail information about the overloads. In this paper, we design and implement a measurement function of smartphone's WCDMA communication quality including overload condition and management system of mobile wireless communication networks about smartphones' communication quality.

• 대한물리의학회지
• /
• 제11권2호
• /
• pp.77-82
• /
• 2016

PURPOSE: The purpose of this study was to investigate the validity of dynamic balance measurements using a smartphone. METHODS: Thirty subjects were selected out of Y-university students without fractures, operation history, and inflammatory arthritis who had not started regular exercise during the past three months. Their dynamic balance ability was measured by the Biodex Balance System (Biodex Medical Systems, Inc., USA) using smartphones. The smartphone utilized in this study was the Galaxy Note4 LTE (SM-N910K, Samsung, Korea), and the application was the Sensor Kinetics pro (Ver.2.1.2, INNOVENTIONS Inc, US). The dynamic balance ability was measured in triplicate. RESULTS: With eyes closed, a low level of correlation (r>0.30, p<0.05) and low reliability (ICC>0.60) were determined between the roll value of the smartphone gyroscope versus the medial/lateral score of the Biodex Balance System. With eyes closed, a low level of correlation (r>0.30, p<0.05) and low reliability (ICC>0.60) were determined between the total value of the smartphone gyroscope versus the total score of the Biodex Balance System. CONCLUSION: This study indicated that using a smartphone can generate highly limited data regarding balance ability. They are unlikely to replace the existing more expensive devices entirely. However, smartphones may be highly useful in environments in which an expensive device is not available or when dynamic balance ability should be measured immediately or within a few hours.

• 한국전문물리치료학회지
• /
• 제20권2호
• /
• pp.60-68
• /
• 2013

The purpose of this study was to assess the intra-rater test-retest reliability of tibial external rotation angle measurement using a smartphone-based photographic goniometer, DrGoniometer (DrG) compared to a three-dimensional motion analysis system (Vicon). The current study showed an interchangeable method using DrG to measure the tibial external rotation angle in standing knee flexion at $90^{\circ}$. Twelve healthy subjects participated in this study. A rest session was conducted 30 minutes later for within-day reliability and five days later for between-day intra-rater test-retest reliability. To assess the validity of the measurement using DrG, we used a three dimensional motion analysis system as a gold standard to measure the angle of tibial external rotation. Intra-class correlation coefficient (ICC) and the standard error of measurement (SEM) values were used to determine the within- and between- day intra-rater test-retest reliability of using DrG and a three dimensional motion analysis system. To assess validity, Pearson correlation coefficients were used for two measurement techniques. The measurement for tibial external rotation had high intra-rater test-retest reliability of within-day (ICC=.88) and between-day (ICC=.83) reliability using DrG and of within-day (ICC=.93) and between-day (ICC=.77) reliability using a three-dimentional motion analysis system. Tibial external rotation angle measurement using DrG was highly correlated with those of the three-dimensional motion analysis system (r=.86). These results represented that the tibial external rotation angle measurement using DrG showed acceptable reliability and validity compared with the use of three-dimensional motion analysis system.

• 한국콘텐츠학회:학술대회논문집
• /
• 한국콘텐츠학회 2016년도 춘계 종합학술대회 논문집
• /
• pp.247-248
• /
• 2016

To investigate activities in the evacuated situation of people, the measurement system is newly constructed, that composed of a wearable sensor device of heart beats rates and mobile devices like an Android smartphone with a bluetooth low energy (BLE) connection. Smartphone not only displays the heart beats variation (HBR) and the current location of evacuation person by Global Positioning System (GPS), but also exports the CSV formatted file that would be used for further analyzing the activity of person in detail. As an example of the application of this system, we show the case of evacuation routes for elderly person in Hizen-Hamashuku Area, Saga Prefecture. Using the proposed measuring system, the activities of evacuates can be clearly shown on the map of Geospatial Information System (GIS).

• 한국산학기술학회논문지
• /
• 제17권6호
• /
• pp.233-238
• /
• 2016

본 연구는 스마트폰의 가속도 센서를 이용하여 정적균형능력을 측정하는데 있어 신뢰도를 알아보고자 실시하였다. 본 연구의 연구대상자는 최근 3개월 이내에 골절, 수술, 염증성 관절염이 없고 정기적인 운동을 시작하지 않은 Y대학교의 학생 30명을 대상으로 하였다. 본 연구에 사용된 스마트폰은 갤럭시S5LTE (SM-G900F, Samsung, Korea, 2014)였고 어플리케이션은 Sensor Kinetics pro (Ver.2.1.2, INNOVENTIONS Inc, US, 2015)를 사용하였다. 정적균형능력은 1회당 3번씩 측정하였으며 하루 간격으로 검사-재검사로 시행되었다. 1차 측정과 2차 측정은 동일하게 진행되었다. 본 연구의 분석은 Wilcoxon 부호순위검정, 급내상관계수(ICC(2,1))를 사용하였다. 본 연구의 연구결과는 다음과 같았다. 눈을 뜬 상태에서 1차 측정과 2차 측정 간에 유의한 차이가 없었고(p>0.05) 강한 양의 상관관계를 보였으며(r>0.75, p<0.05) 매우 높은 일치도(ICC>0.80)를 보였다. 눈을 감은 상태에서 1차 측정과 2차 측정 간에 유의한 차이가 없었고(p>0.05) 강한 양의 상관관계를 보였으며(r>0.75, p<0.05) 매우 높은 일치도(ICC>0.80)를 보였다. 본 연구를 통해 스마트폰은 정적균형능력 측정에 있어 가능성이 있다는 사실을 알 수 있었으며 본 연구가 향후 균형능력측정 전용 어플리케이션 개발에 기초자료가 되기를 기대해본다.

• 한국인터넷방송통신학회논문지
• /
• 제17권2호
• /
• pp.191-197
• /
• 2017

스마트폰의 사용이 보편화됨에 따라 스마트폰을 이용한 다양한 응용서비스가 개발되고 있으며, 추가적인 장치없이 음향 신호를 이용하여 데이터를 송수신하거나 위치를 측정하는 기술이 활발하게 개발되고 있다. 그러나 스마트폰 장치의 한계로 음향 주파수의 선택에 한계가 있고, 음향신호 발생 장치의 전자회로의 비선형성으로 인해 인간이 감지할 수 있는 음향신호 잡음이 발생하는 문제가 있다. 따라서 시끄러운 소리가 나므로 실용화에 어려움이 있다. 본 논문에서는 인간이 감지하는 음향 신호의 크기 측정 방법을 제안하고, 이에 따라 여러 가지 음향 신호를 비교 분석함으로써 음향 통신 및 위치측정 시스템 개발시에 비가청 음향 신호 설계에 활용하도록 한다.

• Smart Structures and Systems
• /
• 제18권3호
• /
• pp.625-642
• /
• 2016

The rapid technology developments in smartphones have created a significant opportunity for their use in structural live load measurements. This paper presents extensive experiments conducted in two stages to investigate this opportunity. Shaking table tests were carried out in the first stage using selected popular smartphones to measure the sinusoidal waves of various frequencies, the sinusoidal sweeping, and earthquake waves. Comparison between smartphone measurements and real inputs showed that the smartphones used in this study gave reliable measurements for harmonic waves in both time and frequency domains. For complex waves, smartphone measurements should be used with caution. In the second stage, three-dimensional motion capture technology was employed to explore the capacity of smartphones for measuring the movement of individuals in walking, bouncing and jumping activities. In these tests, reflective markers were attached to the test subject. The markers' trajectories were recorded by the motion capture system and were taken as references. The smartphone measurements agreed well with the references when the phone was properly fixed. Encouraged by these experimental validation results, smartphones were attached to moving participants of this study. The phones measured the acceleration near the center-of-mass of his or her body. The human-induced loads were then reconstructed by the acceleration measurements in conjunction with a biomechanical model. Satisfactory agreement between the reconstructed forces and that measured by a force plate was observed in several instances, clearly demonstrating the capability of smartphones to accurately assist in obtaining human-induced load measurements.

• 패션비즈니스
• /
• 제25권5호
• /
• pp.88-98
• /
• 2021

In this study, the characteristics of digital anthropometric methods were determined with case studies. These methods were broadly classified into two categories: non-wearable and wearable. Then, these categories were further classified into four types: 3D Scanning, mobile app, smart clothing, and smart tool Among the non-wearable types, the "3D scanning" technique was based on the use of 3D hardware equipment. With this technique, the body shape was measured and the internal body information was obtained. Therefore, it is used in fields of healthcare and fitness. Among the wearable types, "Smart clothing" involves a special clothing that measures human body and a smartphone application. Both the components are linked to a fashion platform, which is based on the measured sizes that help shoppers. The "Smart tool" has the characteristic of measuring only with smart tools and smartphone applications; it does not involve the measurement of images. The common advantage of digital anthropometric methods are as follows: they reduce the time and cost of measurement by enabling self-measurement. Moreover, simple measurements are used to determine the size of anthropometry. Thereafter, it accumulates this data to track the continuous changes in size. From an industrial point of view, digital anthropometric technology should be used to increase sales. The on-demand market can be expanded as global consumers would throng the Korean fashion market. For the consumer, an avatar should be created to fit the user's size. This would provide a fun experience to the user.

• Journal of Positioning, Navigation, and Timing
• /
• 제12권4호
• /
• pp.399-408
• /
• 2023

In this paper, we propose a solution that enables continuous indoor/outdoor positioning of smartphone users through the integration of Pedestrian Dead Reckoning (PDR) and GPS/WiFi signals. Considering that accurate step detection affects the accuracy of PDR, we propose a Deep Neural Network (DNN)-based technology to distinguish between walking and non-walking signals such as walking in place. Furthermore, in order to integrate PDR with GPS and WiFi signals, a technique is used to select a proper measurement by distinguishing between indoor/outdoor environments based on GPS Dilution of Precision (DOP) information. In addition, we propose a technology to adaptively change the measurement error covariance matrix by detecting measurement outliers that mainly occur in the indoor/outdoor transition section through a residual-based χ² test. It is verified through experiments on a testbed that these technologies significantly improve the performance of PDR and PDR/GPS/WiFi fingerprinting-based integrated pedestrian navigation.

• 한국안광학회지
• /
• 제18권4호
• /
• pp.473-479
• /
• 2013

목적: 스마트폰 시청과 알코올 섭취에 따른 눈의 변화와 상관관계를 알아보고자 하였다. 방법: 안질환, 정신질환, 전신질환 그리고 알코올 대사에 관련된 약물복용의 병력이 없는 평소 건전한 음주습관을 가진 대상자 31명(남 18명, 여 13명)을 굴절검사, 각막곡률반경, 안압측정, 각막두께를 측정하고 분석하였다. 결과: 스마트폰 시청에 따른 호흡 중 혈중 알코올의 농도 변화는 15분, 30분, 45분, 60분 그리고 회복기에서 유의하게 감소하였다(p<0.01, p<0.001). 알코올 섭취 후 스마트폰 시청 전과 시청 후, 굴절검사 비교 결과 원주굴절력과 축에서 유의한 변화가 있었다(p=0.005, p=0.001). 알코올 섭취 후 스마트폰 시청에 따른 안압의 변화는 30분부터 유의하게 감소하였으며(p<0.001), 알코올을 섭취 한 상태에서 경과시간에 따른 스마트폰 시청은 각막두께에 유의한 변화를 주지 않았다. 결론: 스마트폰 시청과 알코올 섭취는 원주굴절력과 축 그리고 안압에 유의한 변화를 보인다. 시기능 피로를 초래할 수 있는 스마트폰 시청 및 알코올 섭취는 굴절검사 전 반드시 고려해야 할 요인이다.