• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.11a
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• pp.133-135
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• 2020

최근 CNN(Convolutional Neural Network)은 영상 분류, 객체 인식 등 다양한 비전 분야에서 우수한 성능을 보여주고 있으나, CNN 모델의 계산량 및 메모리가 매우 커짐에 따라 모바일 또는 IoT(lnternet of Things) 장치와 같은 저전력 환경에 적용되기에는 제한이 따른다. 따라서, CNN 모델의 임무 성능을 유지하연서 네트워크 모델을 압축하는 기법들이 연구되고 있다. 본 논문에서는 행렬 분해 기술인 저계수행렬 근사(Low-rank approximation)와 CP(Canonical Polyadic) 분해 기법을 결합하여 CNN 모델을 압축하는 기법을 제안한다. 제안하는 기법은 계층의 유형에 상관없이 하나의 행렬분해 기법만을 적용하는 기존의 기법과 달리 압축 성능을 높이기 위하여 CNN의 계층 타입에 따라 두 가지 분해 기법을 선택적으로 적용한다. 제안기법의 성능검증을 위하여 영상 분류 CNN 모델인 VGG-16, ResNet50, 그리고 MobileNetV2 모델 압축에 적용하였고, 모델의 계층 유형에 따라 두 가지의 분해 기법을 선택적으로 적용함으로써 저계수행렬 근사 기법만 적용한 경우 보다 1.5~12.1 배의 동일한 압축율에서 분류 성능이 향상됨을 확인하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.35-36
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• 2021

딥러닝을 이용한 이미지 처리에서 데이터 셋이 반드시 필요하다. 월패드는 널리 보급되는 다양한 성능을 포함한 IoT가전으로 그 기능의 사용을 돕기 위해서는 해당 월패드에 해당하는 매뉴얼을 제공해야 하고 이를 위해 딥러닝을 이용한 월패드 분류를 이용 할 수 있다. 하지만 월패드 중 일부 모델은 화면의 전반사가 매우 심해 기존의 작은 데이터 셋으로는 딥러닝을 이용한 이미지 분류 성능이 좋지 못하다. 본 논문은 이를 해결하기 위해 추가적으로 데이터 셋을 구축하고 이를 이용해 대규모 데이터로 사전 학습된 VGG16, VGG19, ResNet50, MobileNet 등을 이용해 전이학습을 통해 월패드를 분류한다.

• Annual Conference of KIPS
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• 2024.05a
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• pp.277-278
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• 2024

모바일 엣지 컴퓨팅 기술은 블록체인과 결합하여 모바일 기기의 낮은 컴퓨팅 파워를 보완함과 동시에 추적성, 무결성이 보장된 데이터베이스를 제공하기에, 미래 IoT 환경에서 중추적인 역할을 할 것으로 기대된다. 그러나 블록체인 기반 모바일 엣지 컴퓨팅을 안전하고 효율적으로 사용하기 위해 보안이 함께 동반되어야 하며, 본 논문은 이러한 보안의 하나로써 안전한 그룹 서명과 인증 체계를 위해 고려해야 하는 보안 위협을 살펴보고, 이를 완화하기 위한 보안 기술을 살펴보고자 한다.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.67-72
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• 2020

The fifth generation (5G) mobile communication has an impact on the human life over the whole world, nowadays, through the artificial intelligence (AI) and the internet of things (IoT). The low latency of the 5G new radio (NR) access is implemented by the state-of-the art technologies, such as non-orthogonal multiple access (NOMA). This paper investigates a practical issue that in NOMA, for the practical channel models, such as fading channel environments, the successive interference cancellation (SIC) should be performed on the stronger channel users with low power allocation. Only if the SIC is performed on the user with the stronger channel gain, NOMA performs better than orthogonal multiple access (OMA). Otherwise, NOMA performs worse than OMA. Such the superiority requirement can be easily implemented for the channel being static or slow varying, compared to the block interval time. However, most mobile channels experience fading. And symbol by symbol channel estimations and in turn each symbol time, selections of the SIC-performing user look infeasible in the practical environments. Then practically the block of symbols uses the single channel estimation, which is obtained by the training sequence at the head of the block. In this case, not all the symbol times the SIC is performed on the stronger channel user. Sometimes, we do perform the SIC on the weaker channel user; such cases, NOMA performs worse than OMA. Thus, we can say that by what percent NOMA is better than OMA. This paper calculates analytically the percentage by which NOMA performs better than OMA in the practical mobile communication systems. We show analytically that the percentage for NOMA being better than OMA is only the function of the ratio of the stronger channel gain variance to weaker. In result, not always, but almost time, NOMA could perform better than OMA.

• Journal of Korea Multimedia Society
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• v.17 no.12
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• pp.1473-1483
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• 2014

A public restroom is different from a household toilet in terms of location and a large number of sharing users. In addition, public restroom is usually messy and filthy. Recently, public toilet tends to be clearly managed than before, but it still has hygienic and clear problems. In this paper, we propose a machine-to-machine (M2M)-based public restroom management system to solve these problems, in which the system with a wireless communication device sends the status information of the toilet, such as blockage or trouble detected by a sensor, to the manager of the restroom at a remote location. In particular, we have developed a prototype management system for public restroom taking into account several system requirements, and verified the basic operations and performance of the management system. With the application of the system to public facilities, it will furnish users with more pleasant environments by restroom administrators who can respond effectively to the troubled toilet.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.10
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• pp.1-9
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• 2018

The purpose of this exploratory study is to identify the mobile phone applications (apps) used by foreign tourists visiting South Korea through a pilot study using focus groups and individual interviews. Concentrating on tourist mobile app use in a smart tourism environment and categorized through a taxonomy of mobile applications lays the framework and determines the factors boosting tourism smartphone app trends by foreign tourists visiting South Korea. Researchers collected data through ethnographic methods and analyzed it through qualitative research to uncover major themes within the smart tourism app use phenomenon. The researchers coded, counted, analyzed, and then divided the findings gleaned from a pilot study and interviews into a taxonomy of seven logical smartphone app categories. The labeling and coding of all the data accounting for similarities and differences can be recognized and are logically discussed in the implications of the apps used by tourists to assist tourist destinations. More specifically these findings will assist smart tourism destinations by better understanding foreign tourist smartphone app use behavior. Tourists visiting South Korea interviewed in this study exhibited significant mastery of Internet of Things (IoT) technologies, craved free WiFi access, and utilized smartphone apps for all facets of their travel. Findings show major concentrations of app use in bookings of accommodations, tourist attractions, online shopping, navigation, wayfinding, augmented reality, information searching, language translation, gaming, and online dating while traveling in South Korea.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.96-101
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• 2015

This paper describes a design and implementation of the NFC bridge chip which performs interface between kinds of devices and mobile phones including NFC controller through NFC communication. The NFC bridge chip consists of the digital part and the analog part which are based on NFC Forum standard. Therefore the chip treats RF signals and then transforms the signal to digital data, so it can interface kinds of devices with the digital data. Especially the chip is able to detect RF signals and then wake up the host processor of a device. The wakeup function dramatically decreases the power consumption of the device. The carrier frequency is 13.56MHz, and the data rate is up to 424kbps. The chip has been fabricated with SMIC 180nm mixed-mode technology. Additionally an NFC bridge chip application to the blood glucose measurement system is described for an application example.

• Journal of Internet of Things and Convergence
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• v.6 no.4
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• pp.33-38
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• 2020

It was reported that a mobile application was designed to easily provide natural dyeing information such as natural dye related resources, colors and dyed fabrics in 2007. Since studies on the linkage, application, etc. between natural dye dyeing and IoT are still lacking, diversity of information on the change of dyeing pattern by natural dye dyeing is required. In this study, it was to construct dyeing information by natural dyes, e.g., Lithospermum erythrorhizon, on silk, which has been traditionally used as many fibers in Korea. The extraction of the dye from L. erythrorhizon was carried out under pH4. The dried root of L. erythrorhizon showed dark brownish purple. Silk fabric by a without a mordant typically showed a purple dyed pattern. In the staining by sodium tartrate plus citric acid, silk fabric was stained clear brown. Interestingly, the mordant of iron (II) sulfate, the silk fabric was dyed in a light gray color rather than black. When the mordant of aluminum potassium sulfate was treated with L. erythrorhizon-extracted dye, the results were almost the same as when the mordant was not treated. When the degree of dyeing was evaluated numerically, the treatment of the mordant of potassium dichromate was about 50% darker, and the dyeing by iron (II) sulfate was about 75% darker. These results will be helpful in the study of applying various dye colors using L. erythrorhizon, and it will provide information on dyeing controller and database system construction by dyeing parameters such as dyeing degree, pH concentration, and chromaticity change.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.129-136
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• 2017

Geographic Information System The geographic information system (GIS) has been limited to the government and some public sectors. Recently, the market has been diversified by combining with other areas such as mobile and CRM (Customer Relationship Management). The development direction of GIS technology in the 21st century is Web GIS, 3D GIS, mobile GIS, LBS, etc. as general technology for GIS application system development and spatial information service. In this study, we developed a new concept marking nail (a marking nail with built - in intelligent storage memory device) from the function of simple positioning of a marking nail related to a previously used underground item,, Burial depth, pipe thickness, piping material, management agency, contractor, contact, etc.) and store it in DB server, if necessary.Make it available in the right place. Through this research, it is possible to prevent and minimize various accidents caused by irregular excavation works, etc., and to provide information for establishing countermeasures related to sink holes. In order to provide systematic and reliable information on underground burial management, it was proposed to input information conveniently in the field, and the purpose was to reduce the incidence of buried underground pipes absolutely.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.2
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• pp.397-407
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• 2015

In this paper, we designed 1 chip IC for 3-axis gyroscope and 3-axis accelerometer used for various IoT/M2M mobile devices such as smartphone, wearable device and etc. We especially focused on analysis of gyroscope noise and proposed new architecture for removing various noise generated by gyroscope MEMS and IC. Gyroscope, accelerometer and geo-magnetic sensors are usually used to detect user motion or to estimate moving distance, direction and relative position. It is very important element to designing a low noise IC because very small amount of noise may be accumulated and affect the estimated position or direction. We made a mathematical model of a gyroscope sensor, analyzed the frequency characteristics of MEMS and circuit, designed a low noise, compact and low power 1 chip 6-axis inertial sensor IC including 3-axis gyroscope and 3-axis accelerometer. As a result, designed IC has 0.01dps/${\sqrt{Hz}}$ of gyroscope sensor noise density.