• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1881-1903
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• 2015

With the fast-developing of mobile terminals, positioning techniques based on fingerprinting method draws attention from many researchers even world famous companies. To conquer some shortcomings of the existing fingerprinting systems and further improve its performance, we propose a radio map building and updating technique, which is able to customize the spatial and temporal dependency of radio maps. The method includes indoor propagation and penetration modeling and the analysis of human traffic. Based on the combination of Ray-Tracing Algorithm, Finite-Different Time-Domain and Rough Set Theory, the approach of indoor propagation modeling accurately represents the spatial dependency of the radio map. In terms of temporal dependency, we specifically study the factor of moving people in the interest area. With measurement and statistics, the factor of human traffic is introduced as the temporal updating component. We improve our existing indoor positioning system with the proposed building and updating method, and compare the localization accuracy. The results show that the enhanced system can conquer the influence caused by moving people, and maintain the confidence probability stable during week, which enhance the actual availability and robustness of fingerprinting-based indoor positioning system.

• Laser Solutions
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• v.18 no.1
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• pp.1-6
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• 2015

High welding speed and narrow weld seam are favorable for welding of magnesium alloy. Magnesium alloy is recommended for the smart frame because it has several advantages such as low density, high thermal conductivity, EMI shielding capability and good cast ability. This study is for the assembly welding of the magnesium smart frame with high productivity, good performance and low cost. The window for battery on AZ91D frame produced by die-casting was prepared by CNC machining. Corresponding AZ31 blank of 0.2mm thickness was prepared by die-blanking cut. All system set was fixed at the stationary bed but the laser beam was manipulated by scanner up-to 1,000mm/s speed. The weld joint between AZ31 sheet and AZ91D frame was welded by fiber laser on 850~1,000W output power. The joint showed penetration enough but some humping bead. The distortion by the weld heat was almost free because of the quick dissipation of the heat by small beam size and fast welding. Consequently, the thinner magnesium foil was assembled successfully to the magnesium frame of mobile phone.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.95-102
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• 2021

The urinalysis, which is universally accessible to the general public, has disadvantages of being less objective using sight and purchasing a separate portable urinalysis machine. However, due to the high penetration rate and performance improvement of smartphone created by the development of mobile communication technology, research on urinalysis services using smartphone has been conducted. In this paper, a new urinalysis screening application based on smartphone was developed by supplementing the limitations of the previously studied urinalysis services. The key technology of the application is urinalysis recognition algorithm and urinalysis pad color determination algorithm through image-processing and contour detection. In order to confirm the performance of the developed application, urinalysis strip was photographed and analyzed from various backgrounds and angles.

• Journal of Internet Computing and Services
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• v.11 no.2
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• pp.61-72
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• 2010

This paper addresses the problem of moving object localization using Ultra-Wide-Band(UWB) range measurement and the method of location accuracy improvement of the indoor moving object. Unlike outdoor environment, it is difficult to track moving object position due to various noises in indoor. UWB is a radio technology that has attention for localization applications recently. UWB's ranging technique offer the cm accuracy. Its capabilities for data transmission, range accurate estimation and material penetration are suitable technology for indoor positioning application. This paper propose a positioning algorithm of an moving object using UWB ranging technique and particle filter. Existing positioning algorithms eliminate estimation errors and bias after location estimation of mobile object. But in this paper, the proposed algorithm is that eliminate predictable UWB range distance error first and then estimate the moving object's position. This paper shows that the proposed positioning algorithm is more accurate than existing location algorithms through experiments. In this study, the position of moving object is estimated after the triangulation and eliminating the bias and the ranging error from estimation range between three fixed known anchors and a mobile object using UWB. Finally, a particle filter is used to improve on accuracy of mobile object positioning. The results of experiment show that the proposed localization scheme is more precise under the indoor.

• Journal of Korean Neurosurgical Society
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• v.63 no.2
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• pp.237-247
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• 2020

Objective : Fixation of the C1-2 segment is challenging because of the complex anatomy in the region and the need for a high degree of accuracy to avoid complications. Preoperative 3D-computed tomography (CT) scans can help reduce the risk of complications in the vertebral artery, spinal cord, and nerve roots. However, the patient may be susceptible to injury if the patient's anatomy does not match the preoperative CT scans. The intraoperative 3D image-based navigation systems have reduced complications in instrument-assisted techniques due to greater accuracy. This study aimed to compare the radiologic outcomes of C1-2 fusion surgery between intraoperative CT image-guided operation and fluoroscopy-guided operation. Methods : We retrospectively reviewed the radiologic images of 34 patients who underwent C1-2 fusion spine surgery from January 2009 to November 2018 at our hospital. We assessed 17 cases each of degenerative cervical disease and trauma in a study population of 18 males and 16 females. The mean age was 54.8 years. A total of 139 screws were used and the surgical procedures included 68 screws in the C1 lateral mass, 58 screws in C2 pedicle, nine screws in C2 lamina and C2 pars screws, four lateral mass screws in sub-axial level. Of the 34 patients, 19 patients underwent screw insertion using intraoperative mobile CT. Other patients underwent atlantoaxial fusion with a standard fluoroscopy-guided device. Results : A total of 139 screws were correctly positioned. We analyzed the positions of 135 screws except for the four screws that performed the lateral mass screws in C3 vertebra. Minor screw penetration was observed in seven cases (5.2%), and major pedicle screw penetration was observed in three cases (2.2%). In one case, the malposition of a C2 pedicle screw was confirmed, which was subsequently corrected. There were no complications regarding vertebral artery injury or onset of new neurologic deficits. The screw malposition rate was lower (5.3%) in patients who underwent intraoperative CT-based navigation than that for fluoroscopy-guided cases (10.2%). And we confirmed that the operation time can be significantly reduced by surgery using intraoperative O-arm device. Conclusion : Spinal navigation using intraoperative cone-beam CT scans is reliable for posterior fixation in unstable C1-2 pathologies and can be reduced the operative time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.573-582
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• 2021

In this study, a series of processes for evaluating the effective protection against barriers that should be equipped in institutions that perform reliability tests on high-risk ammunition, such as high-explosive ammunition, were introduced. The impact that high-explosive bombs can have on personnel includes damage to the eardrum and lungs caused by explosion overpressure and penetrating wounds that can be received by fragments generated simultaneously with the explosion. Therefore, a high-explosive with COMP B explosives as its contents were set up, and an explosion protection theory investigation to calculate the degree of damage, numerical calculations and simulations were performed to verify the protection power. A numerical calculation revealed the maximum explosion overpressure on the protective wall when the high-explosive exploded and the penetration force of the fragment against a 50 mm-thick protective wall to be 77.74 kPa and 41.34 mm, respectively. In the simulation verification using AUTODYN, the maximum explosion overpressures affecting the firewall and personnel were 56.68 kPa and 18.175 kPa, respectively, and the penetration of fragments was 35.56 mm. This figure is lower than the human damage limit, and it was judged that the protective power of the barrier would be effective.

• Journal of Korean Medical classics
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• v.30 no.3
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• pp.133-141
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• 2017

Objectives : As of 2013, South Korea ranked number one in the world in smartphone penetration rate with 67.6%. Unfortunately, with the rise of smart phone use, side effects such as fraud, loss of personal information, identity theft, formation and widening of a mobile information gap, and last, but not least, smart phone addiction, also increased. Methods : Seventh (7th)graders from a girls' junior high school in Seoul, the capital of South Korea, we reevaluated the Smart phone Addiction Proneness Scale (S-scale). Among the 9 students classified as high risk users, 5 were randomly selected for a study group, and the remaining 4 students, meanwhile, were designated as a control group. The study group received Korean medicine music therapy (KMMT) in a total of 8 sessions, each session lasting 50 minutes. Both pre- and post-interventions, the two groups completed the S-scale, Harris and Harris' concentration grid exercise, STAI, and STAXI-K. We analyzed the data by t-test and paired t-test using IBM SPSS Statistics. Results : KMMT had a significant influence on proneness to smart phone addiction (t=3.130, p=.035). KMMT had positive effects on concentration improvement (t=-2.935, p=.043), trait-anxiety symptoms improvement (t=2,992, p=.040), and anger-expression control (t=4.416, p=.012). Conclusions : KMMT had positive, improving effects on trait anxiety and anger expression, which in turn enhanced the improvement of concentration as well as the decrease of smart phone-addiction proneness.

• The Journal of the Korea Contents Association
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• v.15 no.9
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• pp.509-526
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• 2015

The study investigated the N-Screen strategies of paid digital contents of foreign newspapers belonging to advanced companies: USA, United Kingdom, and Japan. This research employed the time to launch paid digital content business, whether or not to segment market, and 4p marketing mix strategies for analyzing the strategies. The results show that the strategies, starting around the year 2000, had experience chasm, and then revived since the year 2010, when the penetration rate of mobile devices proliferated. Most newspapers still supply contents under the assumption that they paly in a mass market. The items of paid digital contents are mainly composed of e-paper and digital contents. Regarding the price strategy, soft paywall and combination paywall are largely used. Distribution strategy is subject to whether or not to discriminate the path of digital contents. As for promotion strategy, bundling strategy with newspaper is mostly utilized. The difference between western countries and Japan was found in term of the free trial service.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.200-206
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• 2008

To implement a mobile radio system, wave-propagation models are necessary to determine propagation characteristics accurately, Currently, the empirical/theoretical prediction models for urban environments are fairly well-developed. But there is a lack of a suitable prediction model for mountain region. So in this paper, to develop the prediction model for mountain region, propagation environments are classified based on three basic mechanisms: reflection, diffraction, penetration(absorbtion and scattering), and measurements have been performed for the classified mountain regions including open area, forest and ridge. Using the measurement data, empirical modeling of propagation characteristics are performed, and then a prediction model for mountain region is proposed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.862-865
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• 2013

The smartphone digs deep into our lives, is changing our life. With increases the penetration of smart phones, it getting better performance. In recent years, tend to increase its utilization by an increase in the prevalence of smart phones equipped with NFC short-range wireless communication technology based on RFID in a number of areas, including e-cards, tagging. In this paper, we implement a system that can operate the system by traditional saddlecloth way of waiting waiting waiting standby system more efficient by applying NFC.