• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권6호
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• pp.2377-2397
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• 2020

Human activity recognition is widely used in smart homes, health care and indoor monitor. Traditional approaches all need hardware installation or wearable sensors, which incurs additional costs and imposes many restrictions on usage. Therefore, this paper presents a novel device-free activities recognition system based on the advanced wireless technologies. The fine-grained information channel state information (CSI) in the wireless channel is employed as the indicator of human activities. To improve accuracy, both amplitude and phase information of CSI are extracted and shaped into feature vectors for activities recognition. In addition, we discuss the classification accuracy of different features and select the most stable features for feature matrix. Our experimental evaluation in two laboratories of different size demonstrates that the proposed scheme can achieve an average accuracy over 95% and 90% in different scenarios.

• 한국HCI학회논문지
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• 제11권2호
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• pp.23-30
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• 2016

사물인터넷 시장은 미래의 핵심성장 동력으로 폭발적인 성장을 하고 있다. 이에 세계의 주요 기업들은 사물인터넷 시장 선점과 자사 중심의 생태계 조성을 위해서 사물인터넷 서비스를 경쟁적으로 제공하고자 노력하고 있다. 하지만 이러한 사물인터넷 서비스가 정착되고 기업의 발전에 기여하기 위해서는 사용자들이 진정으로 원하고 체감할 수 있으며 새로운 경험을 할 수 있는 사물인터넷 서비스를 제공하는 것이 필요하다. 이에 본 연구에서는 성공적인 사물인터넷 서비스를 제공하기 위해 사용자 가치 요인을 도출하였다. 이를 위하여 먼저 사물인터넷의 개념과 의미를 파악하고 사물인터넷과 관련한 문헌들을 고찰하여 사물인터넷의 트렌드 매트릭스를 도출하였다. 그리고 사물인터넷 관련 문헌에서 잠재적 서비스 가치 항목을 정리하고, 표적집단면접을 실시하여 문헌에 나타나지 않은 사용자의 실제적 욕구와 기대 항목을 추가하여 사용자 가치 요인을 도출하기 위한 문항을 정리하였다. 마지막으로 이렇게 준비된 문항을 활용하여 설문조사를 진행하였으며, 사물인터넷 서비스의 사용자 가치 요인으로 관리성, 관계성, 친숙성, 확장성, 단순성, 오락성, 안전성, 경제성, 보상성, 자동화, 신속성, 정보성, 환경성의 13가지 요인을 도출하였다. 본 연구는 사물인터넷 서비스를 이해하는데 기반 자료로 활용될 수 있으며, 사용자들이 원하는 사물인터넷 서비스를 개발하기 위한 기준이나 평가 항목으로 활용될 수 있을 것으로 기대된다.

• 한국멀티미디어학회논문지
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• 제20권7호
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• pp.1054-1064
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• 2017

With the development of cloud computing, internet technology and Internet of Things(IoT), most of applications are being smarter and changing from native application to SaaS (Software as a Service) application. New versatile SaaS applications are being released through various app portals (e.g. appstore, googleplay, T-Store, and so on). However, a user has a difficulty in searching, choosing an suitable application to him. It is also hard for him to know what functions of each SaaS application are useful. He wants to be recommended something inter-operated SaaS service according to his personality and his situation. Therefore, this paper presents a way of making mash-up of SaaS applications in order to provide the most convenient inter-operated SaaS service to user. This paper also presents SaaS Application Mash-up Framework (SAMF), complex context and rule matrix. The proposed SAMF is a main system that totally manage SaaS application mash-up service. Complex context and rule matrix are key components in order to recommend what SaaS applications are needed and how those SaaS applications are inter-operated. The SAMF collects complex contexts (User Description, Status Description, SaaS Service Description) in order to choose which SaaS applications are useful, analyze what functions to use, how to mash-up.

• 한국전기전자재료학회논문지
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• 제37권1호
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• pp.112-117
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• 2024

The Internet of Things (IoT) device is a key component for Industry 4.0, which is the network in homes, factories, buildings, and infrastructures to monitor and control the systems. To demonstrate the IoT network, batteries are widely utilized as power sources, and the batteries inevitably require repeated replacement due to their limited capacity. Magneto-mechano-electric (MME) generators are one of the candidate to develop self-powered IoT systems since MME generators can harvest electricity from stray alternating current (AC) magnetic fields arising from electric power cables. Herein, we report a magneto-mechano-triboelectric generator enabled by a ferromagnetic-ferroelectric composite. In the triboelectric nylon matrix, a ferromagnetic carbonyl iron powder (CIP) was introduced to induce magnetic force near the AC magnetic field for MME harvesting. Additionally, a ferroelectric ceramic powder was also added to the MME composite material to enhance the charge-trapping capability during triboelectric harvesting. The final ferromagnetic-ferroelectric composite-based MME triboelectric harvester can generate an open-circuit voltage and a short-circuit current of 110 V and 8 μA, respectively, which were enough to turn on a light emitting diode (LED) and charge a capacitor. These results verify the feasibility of the MME triboelectric generator for not only harvesting electricity from an AC magnetic field but also for various self-powered IoT applications.

• Asian Journal of Innovation and Policy
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• 제9권2호
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• pp.187-206
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• 2020

Under the on-going evolution of the COVID-19 pandemic, estimating the economic impact of the pandemic is highly uncertain and challenging. This situation makes it difficult for policymakers, governors, and economic entities to formulate appropriate responses and decision makings. To provide useful information about the effect of the COVID-19 pandemic on the Korean economy, this study examined macroeconomic impact analysis stemming from the pandemic shocks with different scenarios for the Korean economy. Based on three scenarios using the growth rate of 2020 GDP and consumer expenditure patterns, the 2021 GDP by industry sector was forecast with two new approaches. First, the recovering process of the Korean economy from the shock was analyzed by applying a Flex-IO method. Second, a new forecasting approach combined with an IO coefficient matrix was applied to forecast the future GDP changes. The findings of this study are summarized as follows: First, the total GDP growth rate under the Pessimistic Scenario demonstrates less rebound from the shock than that of the Base Scenario. Second, agriculture, culture, and tourism-related sectors that are suffering from the severe losses of COVID-19 showed lower resilience than other different industries. Third, information and communications technology (ICT) industry maintains a stable growth trend and is expected to take the leading role for the Korean economy in the post-COVID-19 and the Industry 4.0 eras. The findings deliver that it needs to analyze how government expenditure responding the shock into the forecasting model, which can be more useful and reliable to simulate the resilience from the pandemic.

• 전기전자학회논문지
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• 제19권2호
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• pp.142-147
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• 2015

본 논문에서는 자이로 센서와 가속도 센서로부터 얻은 정보를 보정 및 융합하여 자세를 추정하는 칼만 필터 기반 센서 융합 필터의 설계를 제안한다. 최근 센서 네트워크 기술의 발전으로 인해 센터 데이터의 융합 기술이 요구되고 있다. 본 논문에서는 필터의 비선형 시스템 모델을 Jacobian Matrix 연산을 통해 선형 시스템 모델로 변환하며, 오일러 적분을 통해 추정 값을 예측한다. 제안한 필터는 Xilinx 사의 Virtex-6 FPGA Board 를 이용하여 구현하였다. 구현한 필터는 74MHz 동작 주파수로 동작하며, 기존 필터들과 구현한 필터를 비교하여 추정 자세의 정확도 및 신뢰도를 확인하였다.

• 한국산업보건학회지
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• 제33권1호
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• pp.78-90
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• 2023

Objectives: The purpose of this study is to standardize the process code of the work environment measurement database (WEMD) for the construction of a job-exposure matrix (JEM). Methods: The standard process code (SPC) was reclassified based on process similarity and drawing upon the code used in the existing K2B. It was supplemented through review by industrial hygiene experts. In addition, an index word database related to SPC was created and used for SPC search. A pilot evaluation project was conducted by experts to evaluate the validity of the newly reclassified standard process code. Results: A total of 70 final SPCs were developed, including 31 processes related to the construction industry. Using the Shiny program, we developed a standard code finder that can be used on the web (https://kscf.shinyapps.io/scf_app/). As a result of the pilot evaluation, it was determined that it was easier to search for standard codes than previous codes, so it was highly utilized. Conclusions: It is expected that JEM construction using industry-process information drawing on WEMD data will be possible using the 70 newly standardized process codes.

• 해양환경안전학회지
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• 제23권3호
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• pp.242-249
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• 2017

In order to develop an HNS safety management system to assess and visualize hazard levels via an automated method, we have conceptualized and configured a sample system. It is designed to quantify the risk of a vessel carrying HNS with a matrix method along navigational route and indicate hazards distribution with a contour map. The basic system which provides a visualized degree of hazards in real time has been introduced for the safe navigation of HNS ships. This is useful not only for decision making and circumstantial judgment but may also be utilized for HNS safety management with a risk base. Moreover, this system could be extended to address the navigational safety of marine traffic as well as of autonomous vessels in the near future if the sensors used are connected with IoT technology.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.1039-1040
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• 2015

최근 IoT 및 인공지능 기술을 활용한 상황 정보 예측 서비스가 각광을 받고 있다. 본 논문에서는 특정 메타 데이터(Meta Data)로부터 입력되는 정보를 기반으로 상황 정보 분석 및 예측하는 프로세스를 제안한다. 주성분 분석 및 데이터의 집단화(Corpus), 문서 매트릭스(Document Matrix), 단어 빈도수(Frequency)에 따른 데이터 전처리 과정을 통해 상황정보 데이터를 확보한다. 또한 연관 규칙분석을 통해 분류된 데이터의 연관성을 분석하여 예측 데이터의 연관성을 확보한다. 제안하는 상황정보 분석 및 예측 모델은 R을 적용하여 설계한다.

• 한국통신학회논문지
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• 제42권2호
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• pp.307-315
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• 2017

암호시스템에서 난수발생기는 필수적인 요소이다. 최근에 IoT, Sensor Network, SmartHome와 같은 소형 디바이스를 사용하는 환경이 등장하면서, 이에 적합한 다양한 경량 암호들이 개발되고 있다. 하지만 리소스 제한, 엔트로피 수집의 어려움 등의 문제로 인하여, 기존의 데스크 탑에 초점을 두고 만들어진 난수발생기가 제대로 동작하는 것이 어려워지고 있다. 본 논문에서 경량 환경에서 안전한 난수를 생성하는 방법으로 경량 난수발생기 설계를 소개한다. 구조는 헨켈 매트릭스와 블록암호를 사용하고 잡음원으로 센서를 사용한다. 또한 소형 디바이스 중에서 가장 대표적인 Arduino보드에 설계한 경량 난수발생기를 구현하고, 구현 결과로 센서 데이터와 최종 출력 난수의 엔트로피 값을 측정하고 평가함으로써 효율성과 안전성을 확인한다.