• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.307-309
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• 2016

본고에서는 WiFi, ZigBee, 블루투스 등 무선 통신 기술을 이용해서 로봇, 헬스케어, 스마트그리드, 자율자동차 분야 등에서 무선에 의한 센싱 및 전력 전송을 제어하는 시스템에 대해서 기술하였다. 최근에 사물인터넷 (Interne of Things) 및 사물통신(Machine to Machine)을 이용한 다양한 응용이 많은 분야에서 제기되고 있으며 이를 위해서는 제어, 컴퓨팅, 네트워킹 기술이 융합된 기술을 요구한다. 기존의 제어 중심이었던 임베디드 시스템에 유무선 통신망을 이용한 컴퓨팅 기술이 융합된 가상물리 시스템(Cyber Physical System)이 미국 및 유럽에서 향후 국가 주도 기술로 채택되어 연 산 학이 협력하여 추진 중이다. 본고에서는 이러한 기술 개념에 일치하는 무선을 이용한 센싱에 의해 무선으로 전력을 전송하는 시스템을 제어하는 기술을 구현하고 기술하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.549-551
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• 2016

과학기술의 발전에 따라 현대인들은 실외보다는 실내공간에 머무르는 시간이 과거에 비해 훨씬늘어 나고 있다. 최근까지도 실외 대기환경에 대해서는 매우 다양한 연구와, 개선 노력이 진행 중에 있으나 실내에서의 공기의 질 문제는 상대적으로 가볍게 여겨져 온 것이 사실이다. 실내공기의 오염은 자연적인 희석률이 큰 실외 대기환경의 오염과 달리, 희석률이 매우 낮아 한번 오염된 공기가 지속적으로 순환되면서 실내에 머무르고 있는 사람의 건강에 매우 나쁜 영향을 끼친다. 본 연구에서는 실내에서 거주하는 사람의 이동특성, 생활 형태를 반영한 능동적 실내환경 제어체계에 대한 연구를 위하여 실시간으로 측정된 공기의 질을 측정하여 사용자의 스마트기기로 정보를 전송하는 공기측정기장치 알람봇과 운영 어플리케이션을 구현 하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.628-631
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• 2014

최근 다양한 형태의 스마트 기기 출현과 대중적 보급으로 인해 고속 데이터 전송에 대한 수요가 나날이 증가하고 있다. 이런 요구사항을 수용하기 위해 셀룰러 사업자 및 이동통신 장비 제조업체는 많은 새로운 기술에 대한 연구를 진행하였으며 이에 대한 결과로 향후 셀룰러 네트워크에서 성능 및 커버리지 향상을 위해 소형셀 기술을 하나의 중요한 요소 기술로 고려하고 있다. 셀룰러 네트워크에서 소형셀 기술은 데이터 요구량이 많은 위치에 소형셀을 밀집 배치하고 매크로 기지국 및 소형셀 기지국의 밀접한 협력을 통해 무선 네트워크의 용량을 증가시키는 것을 의미한다. 따라서 본 논문에서는 매크로 셀과 소형 셀이 다층으로 배치된 셀룰러 이동통신 구조를 제시하고 다층셀간의 협력을 통해 성능을 향상시킬 수 있는 다양한 요소기술들에 대해서 기술한다. 또, 이들 요소기술들을 바탕으로 최근 3GPP에서 활발히 논의되고 있는 LTE 소형셀 향상 표준화 동향에 대해 기술한다.

• 한국인터넷방송통신학회논문지
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• 제19권1호
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• pp.63-68
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• 2019

최근 들어 스마트 팩토리, 차량 내 통신망, 광대역 전력망 등 다양한 응용분야에서 단대단 네트워크 지연시간(End-to-end network delay)에 대하여 엄격한 제한(bound)을 요구하고 있다. 이에 따라 기존 Integrated Services (IntServ) 프레임워크에서의 플로우 기반 스케줄러를 바탕으로 하는 해법들이 다시 제안되고 있다. 하지만 많은 수의 플로우를 구분하여 스케줄 하는 것은 복잡도가 커서 구현하기 어렵다. 차선책인 Class기반 스케줄러는 노드를 지나면서 burst가 기하급수적으로 커지기 때문에 지연시간을 제한하기 어렵다. 이에 따라 트래픽 regulator와 class 기반 스케줄러를 앞뒤로 배치하여 burst의 크기를 줄이면서 동시에 스케줄러의 복잡도를 낮추려는 연구가 등장하고 있다. 본 연구에서는 이러한 regulator와 스케줄러가 하나의 서버에서 간단히 구현되는 방안을 제시하고 성능을 분석하여 대규모 네트워크에서도 수 ms 이내의 최대 delay를 보장함을 보였다.

• 한국컴퓨터정보학회논문지
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• 제24권1호
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• pp.121-128
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• 2019

An Internet of Things(IoT) technology which provides intelligent services by combining context-awareness based intelligences, inter-communication is made of between things and things or between things and person through the network connected with intelligent things is spreading rapidly. Especially as this technology is converged into smart device, mobile, cloud, big data technologies, it is applied into various domains. Therefore, this is different from existing Web or Mobile Application. New types of IoT applications are emerging by adapting IoT into Web or mobile. Because IoT application is not only focused on software but also considering hardware or things aspect, there are limitations existing development process. Existing development processes don't consider analysis and design techniques considering both hardware and things. We propose not only a meta-model for development process which can support IoT application's development but also meta-models for main activities in this paper. Especially we define modeling elements by using UML's extension mechanisms, provide development process, and suggest design techniques how to apply those elements into IoT application's modeling phase. Because there are many types of IoT application's type, we propose an Android and Arduino-based on IoT application as a case study. We expect that proposed technique can be applied into many of various IoT application development and design with a form of flexible and extensible as well as main functionalities or elements are more concretely described. As a result, it brings IoT application's flexibility and the effect of quality improvement.

• PNF and Movement
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• 제17권1호
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• pp.57-68
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• 2019

Purpose: This study is an investigation of the effects of long-term smart phone usage and of stretching on muscle stiffness, concentration, and visual acuity. Methods: Forty healthy young adults voluntarily participated in the study and were measured for muscle stiffness, concentration, and visual acuity before smartphone usage and after 30 minutes, 60 minutes, and 90 minutes of smartphone usage. The participants were randomly allocated to the intervention group (n=20) and the control group (n=20). Five minutes after the stretching exercise and eye exercise intervention, the participants were remeasured. Results: After long-term smartphone usage, increases in muscle stiffness and concentration were statistically significant (p<0.05), whereas decreases in visual acuity were statistically significant (p<0.05). After the stretching exercise and eye exercise intervention, muscle stiffness significantly decreased (p<0.05) and visual acuity significantly increased (p<0.05). Concentration, according to the stretching exercise and eye exercise intervention, showed no significant pre- or post-test difference. Conclusion: The results from this study indicate that long-term smartphone usage effectively improved concentration but increased muscle stiffness and decreased visual acuity. Appropriate stretching and eye movement during long-term smartphones usage should mitigate the effects on muscle stiffness and visual acuity. Furthermore, smartphones should be considered an effective tool for concentration training when coupled with the development of appropriate applications.

• Smart Structures and Systems
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• 제23권5호
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• pp.495-506
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• 2019

This paper presents the results of axial pressure testing on reinforced concrete columns (RCCs) filled with confined normal concrete (NC) and high-strength concrete (HSC) using glass-fiber reinforced plastic pipes (GRP) casing as well as fiber reinforced polymer (FRP). This study aims to evaluate the behavior and mechanical properties of columns confined with GRP casing and FRP wrapping under pressure loads. The major parameters in the experiments were the type of concrete, the effect of GRP casing and FRP wrapping, as well as the number of FRP layers. 12 cylindrical RCCs (150*600) mm were prepared and divided into two groups, NC and HSC, and each group was divided into two parts. In each part, one column was without FRP strengthening layer, a column was wrapped with one FRP layer and another column with two FRP layers. All columns were tested under concentrated compression load. The results of the study showed that the utilization of FRP wrapping and GRP casing improved compression capacity and ductility of RCCs. The addition of one and two layers-FRP wrapping increased compression capacity in the NC group to an average of 18.5% and 26.5% and to an average of 10.2% and 24.8% in the HSC group. Meanwhile, the utilization of GRP casing increased the compression capacity of the columns by 4 times in the NC group and 3.38 times in the HSC group. The results indicated that although both FRP wrapping and GRP casing result in confinement, the GRP casing resulted in increased compression capacity and ductility of the RCCs due to higher confinement. Furthermore, the confinement effect was higher on columns made with NC.

• Composites Research
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• 제34권2호
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• pp.108-114
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• 2021

일반적으로 그래핀 플레이크는 산화그래핀을 화학적 또는 열적 환원 공정을 통해 환원그래핀으로 변환하여 대량 생산하고 있다. 그래핀 플레이크는 다양한 형태로 응용되는데, 그 중 진공여과를 이용한 적층 공정을 통해 종이형 필름으로 제작이 가능하다. 그래핀 종이는 신축성이 부족한 단점이 있어 신축성 소자 응용에 제약이 있다. 본 연구에서는 신축성이 있는 그래핀 종이를 제작하기 위하여, 그래핀 종이에 주름을 만들었다. 신축성이 뛰어난 접착 필름을 미리 늘린 후, 그 위에 그래핀 종이를 붙이고, 접착 필름을 원래 상태로 놓아 주어 그래핀 종이에 주름을 만들었다. 이 때, 접착 필름에 가하는 당김 정도 및 젖은 상태에 따라 주름의 형상이 변하는 것을 실험적으로 관찰하였다. 특히, 그래핀 종이와 접착 필름의 전단 탄성 계수 차에 의하여 주름의 주기가 바뀌는 현상을 관찰하였다.

• Journal of Information Technology Applications and Management
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• 제27권6호
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• pp.53-73
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• 2020

Many prior studies have been conducted that positive reviews increase the intention to purchase. However, there are very few papers that have studied the impact of review search on purchase satisfaction. It is meaningful to study the impact of review search on purchase satisfaction as it can lead the business successfully by inducing repurchase. There is also no study of how review search have different effects on purchase satisfaction among countries. Given the growing number of cross-border e-commerce, we believe that the need for research is high because identifying these differences between countries can have a very important impact on a company's successful overseas expansion. Therefore, in this study, the impact of positive and negative review search on purchase satisfaction and the national impact were set up as a research model. In order to verify this research model, the survey was distributed to those who experienced online purchase in Korea and China, and a total of 234 copies were collected, including 125 copies in Korea, 109 copies in China, and the research model was verified using Smart-PLS structural equation analysis tools. First, positive review search has been shown to positively affect purchase satisfaction. Second, it has been shown that negative review search also has a positive effect on purchase satisfaction. Third, the impact of positive and negative review search on purchase satisfaction was different between Korea and China. While Korea is more aggressive in review search than China due to its high tendency to avoid uncertainty, China is less likely to avoid uncertainty than Korea and is more likely to rely on brand familiarity. Therefore, according to the uncertainty avoidance moderation effect the impact of positive and negative review search on purchase satisfaction was higher in Korea than in China. In this study, Shopping mall managers need to take strategic measures to maximize shopping mall performance by recognizing positive aspects of negative review search on purchase satisfaction. Companies and managers in Korea and China can establish strategies to promote product sales when companies enter the global market.

• International Journal of Advanced Culture Technology
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• 제8권4호
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• pp.263-270
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• 2020

The growth of the mobile app markets has made it popular among people who recommend relevant information about restaurants. The recommendation service app based on AI Chatbot is that it can efficiently manage time and finances by making it easy for restaurant consumers to easily access the information they want anytime, anywhere. Eating out consumers use smartphone applications for finding restaurants, making reservations, and getting reviews and how to use them. In addition, social attention has recently been focused on the research of AI chatbot. The Chatbot is combined with the mobile messenger platform and enabling various services due to the text-type interactive service. It also helps users to find the services and data that they need information tersely. Applying this to restaurant recommendation services will increase the reliability of the information in providing personal information. In this paper, an artificial intelligence chatbot-based smartphone restaurant recommendation app using personalization information is proposed. The recommendation service app utilizes personalization information such as gender, age, interests, occupation, search records, visit records, wish lists, reviews, and real-time location information. Users can get recommendations for restaurants that fir their purpose through chatting using AI chatbot. Furthermore, it is possible to check real-time information about restaurants, make reservations, and write reviews. The proposed app uses a collaborative filtering recommendation system, and users receive information on dining out using artificial intelligence chatbots. Through chatbots, users can receive customized services using personal information while minimizing time and space limitations.