• Journal of Internet Computing and Services
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• v.22 no.1
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• pp.31-39
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• 2021

Obtaining delivery addresses from calls is one of the most important processes in TV home shopping business. By automating this process, the operational efficiency of TV home shopping can be increased. In this paper, a method of recognizing and validating road name address, which is the address system of South Korea, from speech oriented text is proposed. The speech oriented text has three challenges. The first is that the numbers are represented in the form of pronunciation. The second is that the recorded address has noises that are made from repeated pronunciation of the same address, or unordered address. The third is that the readability of the resulted address. For resolving these problems, the proposed method enhances the existing address databases provided by the Korea Post and Ministry of the Interior and Safety. Various types of pronouncing address are added, and heuristic rules for dividing ambiguous pronunciations are employed. And the processed address is validated by checking the existence in the official address database. Even though, this proposed method is for the STT result of the address pronunciation, this also can be used for any 3^rd party services that need to validate road name address. The proposed method works robustly on noises such as positions change or omission of elements.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.301-308
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• 2021

It is important to develop a digital SOC (Social Overhead Capital) maintenance system for preemptive maintenance in response to the rapid aging of social infrastructures. Abnormal signals induced from structures can be detected quickly and optimal decisions can be made promptly using IoT sensors deployed on the structures. In this study, a digital SOC monitoring system incorporating a multimetric IoT sensor was developed for long-term monitoring, for use in cloud-computing server for automated and powerful data analysis, and for establishing databases to perform : (1) multimetric sensing, (2) long-term operation, and (3) LTE-based direct communication. The developed sensor had three axes of acceleration, and five axes of strain sensing channels for multimetric sensing, and had an event-driven power management system that activated the sensors only when vibration exceeded a predetermined limit, or the timer was triggered. The power management system could reduce power consumption, and an additional solar panel charging could enable long-term operation. Data from the sensors were transmitted to the server in real-time via low-power LTE-CAT M1 communication, which does not require an additional gateway device. Furthermore, the cloud server was developed to receive multi-variable data from the sensor, and perform a displacement fusion algorithm to obtain reference-free structural displacement for ambient structural assessment. The proposed digital SOC system was experimentally validated on a steel railroad and concrete girder bridge.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.25-32
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• 2019

The purpose of this study is to investigate how to make a proper investment in ICO in the market. Previously, companies used to borrow money from banks or to obtain investments from venture capital (VC) and angel investors, but now ICOs are used as a new type of funding and financing model. The ICO sells the tokens or coins created on the blockchain openly online to raise the necessary funds, and provides the market value by paying the tokens or coins as much as the investment amount. According to this study, the limitations of the ICO market are (1) difficulties in evaluating the company, (2) uncertainties in investments, (3) lack of legal safeguards, and (4) measures to secure corporate stability after recruitment. At present, there is no way to cope with this systematically since the ICO is not protected in the legal framework. Nevertheless, we investigated the ways to make proper investment in the existing ICO market. In investing in ICO, investors should (1) consider investment methods and profitability, and (2) verify and judge investment fraud through various channels (ex. Homepage, composition team profile, etc.) and make investments based on this. This study will contribute to the formation of a healthy ICO market by understanding the newly emerged ICO market and studying the considerations when investing in it, thereby contributing to the right investor training and reducing the mass production of consumer damages caused by fraud. The limitation of this study is that the domestic ICO has not yet been examined in the legal framework, so further research is needed when policy changes occur in the future.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.2
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• pp.23-36
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• 2005

The main obstacle hindering the wide deployment of identity-based cryptosystem is that the entity responsible for creating the private key has too much power. As a result, private keys are no longer private. One obvious solution to this problem is to apply the threshold technique. However, this increases the authentication computation, and communication cost during the key issuing phase. In this paper, we propose a new effi ient model for issuing multiple private keys in identity-based encryption schemes based on the Weil pairing that also alleviates the key escrow problem. In our system, the private key of a user is divided into two components, KGK (Key Description Key) and KUD(Key Usage Desscriptor), which are issued separately by different parties. The KGK is issued in a threshold manner by KIC (Key Issuing Center), whereas the KW is issued by a single authority called KUM (Key Usage Manager). Changing KW results in a different private key. As a result, a user can efficiently obtain a new private key by interacting with KUM. We can also adapt Gentry's time-slot based private key revocation approach to our scheme more efficiently than others. We also show the security of the system and its efficiency by analyzing the existing systems.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.6
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• pp.141-148
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• 2003

The self-healing key distribution scheme with revocation capability proposed by Staddon et al. enables a dynamic group of users to establish a group key over an unreliable network, and has the ability to revoke users from and add users to the group while being resistant to collusion attacks. In such a protocol, if some packet gets lost, users ale still capable of recovering the group key using the received packets without requesting additional transmission from the group manager. In this scheme, the storage overhead at each group member is O($m^2$1og p) and the broadcast message size of a group manager is O( ((m$t^2$+mt)log p), where m is the number of sessions, t is the maximum number of colluding group members, and p is a prime number that is large enough to accommodate a cryptographic key. In this paper we describe the more efficient self-healing key distribution scheme with revocation capability, which achieves the same goal with O(mlog p) storage overhead and O(($t^2$+mt)log p) communication overhead. We can reduce storage overhead at each group member and the broadcast message size of the group manager without adding additional computations at user's end and group manager's end.

• Design & Manufacturing
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• v.15 no.2
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• pp.11-16
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• 2021

Recently, three-dimensional (3D) cell culture systems, which are superior to conventional two-dimensional (2D) vascular systems that mimic the in vivo environment, are being actively studied to reproduce drug responses and cell differentiation in organisms. Conventional two-dimensional cell culture methods (scaffold-based and non-scaffold-based) have a limited cell growth rate because the culture cannot supply the culture medium as consistently as microvessels. To solve this problem, we would like to propose a 3D culture system with an environment similar to living cells by continuously supplying the culture medium to the bottom of the 3D cell support. The 3D culture system is a structure in which microvascular structures are combined under a scaffold (agar, collagen, etc.) where cells can settle and grow. First, we have manufactured molds for the formation of four types of microvessel-mimicking chips: width / height ①100 ㎛ / 100 ㎛, ②100 ㎛ / 50 ㎛, ③ 150 ㎛ / 100 ㎛, and ④ 200 ㎛ / 100 ㎛. By injection molding, four types of microfluidic chips were made with GPPS (general purpose polystyrene), and a 100㎛-thick PDMS (polydimethylsiloxane) film was attached to the top of each microfluidic chip. As a result of observing the flow of the culture medium in the microchannel, it was confirmed that when the aspect ratio (height/width) of the microchannel is 1.5 or more, the fluid flows from the inlet to the outlet without a backflow phenomenon. In addition, the culture efficiency experiments of colorectal cancer cells (SW490) were performed in a 3D culture system in which PDMS films with different pore diameters (1/25/45 ㎛) were combined on a microfluidic chip. As a result, it was found that the cell growth rate increased up to 1.3 times and the cell death rate decreased by 71% as a result of the 3D culture system having a hole membrane with a diameter of 10 ㎛ or more compared to the conventional commercial. Based on the results of this study, it is possible to expand and build various 3D cell culture systems that can maximize cell culture efficiency by cell type by adjusting the shape of the microchannel, the size of the film hole, and the flow rate of the inlet.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.613-621
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• 2021

This study conducted a network analysis to determine how COVID-19 vaccine-related issue spread on Twitter during the introduction stage of the COVID-19. Issue diffusion tendency is analyzed according to the time period: phase 1 (initiation of vaccine introduction: March 7 - April 3, 2021), phase 2 (stagnant period of vaccination: April 4 - April 22, 2021), and phase 3 (increase of vaccination: April 23 - May 5, 2021). NodeXL was used for data collection and analysis. Daily Twitter network data were collected by entering search terms highly related to the COVID-19 vaccine. This study found that side effects-related opinions were repeatedly formed throughout the analysis period. As the vaccination rate increased and death cases were reported on media, death-related issues also emerged on Twitter. On the other hand, vaccine safety did not receive much attention on Twitter. The results of this study highlight the role of social media as a channel of issue diffusion when a national disaster strikes. We emphasize the need for the government to monitor public opinions on social media and reflect them in crisis communication strategies.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.367-373
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• 2023

Aircrews and passengers are exposed to radiation from cosmic rays and secondary scattered rays generated by reactions with air or aircraft. For aircrews, radiation safety management is based on the exposure dose calculated using a space-weather environment simulation. However, the exposure dose varies depending on solar activity, altitude, flight path, etc., so measuring by route is more suggestive than the calculation. In this study, we developed an instrument to measure the cosmic radiation dose using a general-purpose Si sensor and a multichannel analyzer. The dose calculation applied the algorithm of CRaTER (Cosmic Ray Telescope for the Effects of Radiation), a space radiation measuring device of NASA. Energy and dose calibration was performed with Cs-137 662 keV gamma rays at a standard calibration facility, and good dose rate dependence was confirmed in the experimental range. Using the instrument, the dose was directly measured on the international line between Dubai and Incheon in May 2023, and it was similar to the result calculated by KREAM (Korean Radiation Exposure Assessment Model for Aviation Route Dose) within 12%. It was confirmed that the dose increased as the altitude and latitude increased, consistent with the calculation results by KREAM. Some limitations require more verification experiments. However, we confirmed it has sufficient utilization potential as a cost-effective measuring instrument for monitoring exposure dose inside or on personal aircraft.

• The Journal of the Acoustical Society of Korea
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• v.43 no.4
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• pp.414-421
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• 2024

In this paper, we design and verify a system that can detect piping leakage noise in an environment with significant reverberation and reflection using a multi-channel acoustic sensor module as a technology to prevent major plant accidents caused by leakage. Four-channel microphones arranged in a tetrahedron are designed as a single sensor module to measure three-dimensional sound intensity vectors. In an environment with large effects of reverberation and reflection, the measurement error of each sensor module increases on average, so after placing multiple sensor modules in the field, measurement results showing locations with large errors due to effects such as reflection are excluded. Using the intersection between three-dimensional vectors obtained from several pairs of sensor modules, the coordinates where the sound source is located are estimated, and outliers (e.g., positions estimated to be outside the site, positions estimated to be far from the average position) are detected and excluded among the points. For achieving aforementioned goal, an excluding algorithm by deciding the outliers among the estimated positions was proposed. By visualizing the estimated location coordinates of the leakage sound on the site drawing within 1 second, we construct and verify a system that can detect the location of the leakage sound in real time and enable immediate response. This study is expected to contribute to improving accident response capabilities and ensuring safety in large plants.

• Journal of Chest Surgery
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• v.32 no.6
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• pp.579-583
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• 1999

Background: Thoracic sympathicotomy has been used safely and successfully to manage palmar hyperhidrosis. The preoperative and postoperative recording of Sympathetic Skin Responses(SSR) was performed for objective evaluation and follow-up of thoracic sympathicotomy in hyperhidrosis patients, and also for ascertaining the clinical usefullness of SSR. Material and Method: The recording of SSR was performed on 15 patients suffering from palmar hyperhidrosis with Medelec Sapphire Plus electromyogragh before and after thoracic sympathicotomy. Eletrical stimuli on the right median nerve was made in patients in supine position and results were recorded on right and left palms with soles at the same time by 4 channels. Skin temperatures were also monitored simultaneously. T2,3 sympathicotomy was performed with VATS in every patients. SSR was done in 2 patients one month later. Result: Clinically, all patients had symptomatic improvement with satisfaction. Postoperative complication was small amount of residual pneumothorax in 5 patients but it was absorbed sponteneously. There was no recurrence during follow-up period and ten patients(66%) complained compensatory hyperhidrosis. After operation, SSR change was shown in every 15 patients. Abolition of SSR on both palms was achieved in 12 patients(80%) and on both soles in 6 patients. In the other 3 patients, the latencies were significantly delayed and the amplitudes were significantly reduced at both palms and soles. In two patients who were examined at one month later after operation, similar results with postoperative SSRs were shown. The skin temperature on preoperative both palm and sole were lower than normal temperature, and those on postoperative both palm and sole were increased. Those had statistical significance(p<0.05), and the temperature on the palm was increased higher that than on the sole. Conclusion: After thoracic sympathicotomy was performed on palmar hyperhidrosis patients, an increment of skin temperatures and SSR changes were achieved at both palms and soles of all patients. Palmar SSRs were completely abolished in 12 patients(80%), and similar results of postoperative SSRs were achieved. The recording of SSR may be useful to easily and objectively assess the completeness of sympathicotomy and the follow-up of recurrence in hyperhidrosis patients.