• Journal of Satellite, Information and Communications
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• v.12 no.3
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• pp.98-102
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• 2017

In this paper, we study RF-powered backscatter cognitive radio networks to improve the performance for the secondary user which is backscatter radio based wireless sensors. In our proposed model, we consider an avoiding the doubly round-trip attenuation to add a carrier emitter and utilization of spectrum sensing information. When the primary channel is busy, the secondary user is able to harvest RF energy from the channel through a hybrid-access point (H-AP) and a carrier emitter. When the channel becomes idle, the secondary user will be use the harvested energy to operate wireless sensors, to use the sensing and to backscatter through the carrier emitter. We model mathematically the deterministic and multisource elements of a number of tagged channels. In the proposed communication environment, we show the BER performance of the backscatter communication using WiFi signal.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.221-227
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• 2014

This paper presented a design which was a minimized remote control robot. This remote control robot was created for preventing life damage from conflagrations, nuclear events and HF gas accidents. This robot's system based smart phone that had camera and GPS systems. When fire came out, The robot figured out that how big fire was, where the fire was started and various aspects of situations. And The robot broadcasted the informations to smart phone using mobile application and wi-fi camera. By doing these, the fire mans could more accurate and be easier to plan a strategy for saving life. The body of robot are 2 parts. One is a car and the other one is a remote controller. By the power, 1step to 10steps, of grabbing remote controller could change the car's speed to move. Also, The prototype robot was already confirmed its utility itself.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.6
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• pp.203-209
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• 2017

Low birth rates and aging problems are raising a big issue in the worldwide. Recently, Korea also has no one to caring children who have low discernment and old ones who have Alzheimer's disease because of growing nuclear families and dual income furnitures. Therefore many serious crimes like kidnappings were occurred by people who have mental problems or bad intentions. Even though missing and ding alone are increasing together. The result of it, the needs of potable GPS system, to tracking for the olds and week ones, is highly growing nowadays. This paper introduce producing prototype tracker, looks like fashion accessories, which is using GPS, Zigbee and WiFi. It expects developing many accessory types of trackers effectively helps protect children and old ones from kidnappers at a low cost in this aging society.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.1-10
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• 2024

The radio propagation characteristics of the 6, 10, and 17 GHz frequency bands in multiple paths in an indoor lobby environment were analyzed. The line-of-sight (LOS) and non-LOS (NLOS) paths were measured from a distance of 2-16 m (0.5 m intervals) from the transmitting to the receiving antenna positions. For basic transmission losses, three parameters were compared using the floating intercept path loss model corresponding to the path. For a root mean square delay spread, the measurement results were compared for cumulative probabilities of 10, 50, and 90%. Propagation loss and propagation delay occurred in all measured frequencies owing to the existence of pillars and an unusual lobby structure. Thus, a measurement scenario for an indoor lobby environment and the provision of standard measurement data was proposed. The results may facilitate research on the radio propagation characteristics of 5G and millimeter-wave bands in indoor lobby environments with various structures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8879-8888
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• 2015

When the disaster like earthquake in urban area occur, due to the collapse accidents for subway, tunnel space with buildings or underground area, enormous property and human damage are happened. Specially, since it is difficult to identify survived status of humans within collapsed debris and accurately buried locations of the humans, inputs of considerable time and manpower for rescuing them are required. Besides, secondary damage can be occurred by additional collapses. The aim of this study is to propose a stochastic location positioning method that enables to provide aid information by determining locations of mobile devices for buried persons in 2-D plane using wireless communication technologies. This study selected a detection method for buried persons based on Wi-Fi signal, and identified characteristics of signal strengths by distance unit. Using these methods, a stochastic location detection model in 2-D plane was built. It is expected that this technology will be utilized as a core technology that can protects safety and human life of the public by providing data for rescuing quickly buried persons in cases of national disasters for future.

• Electronics and Telecommunications Trends
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• v.23 no.2 s.110
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• pp.91-97
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• 2008

최근 들어 이동통신사업자를 중심으로 펨토셀을 이용한 서비스 도입에 대한 관심이 높아지고 있다. 유럽의 경우 FMC와 FMS 서비스가 격돌하고 있고, 미국은 펨토셀 FMS 서비스에 관심을 가지고 있으며, 일본은 FMC 서비스에서 펨토셀 도입을 고려하고 있다. 이와 같이, 세계 각국에서 펨토셀에 대한 관심이 증가하고 있으나, 아직까지 표준이 정해지지 않은 기술이며 상용화를 위해서는 해결해야 할 과제가 남아 있다. 펨토셀을 도입하면 실내 커버리지 확대, 통화 품질 향상, 영업비용 절감 등 다양한 이점이 있으며, 가입자와 사업자 모두에게 이익을 제공할 수 있는 상당한 성장 잠재력을 가지고 있으므로 펨토셀에 대한 연구가 필요하다. 본 연구는 펨토셀의 정의 및 장단점, Wi-Fi와 Bluetooth 등과 같은 기술과의 경쟁력 분석, 국내외 펨토셀 시장현황 및 업체동향을 살펴본다. 또한 펨토셀의 수익원천을 파악할 수 있는 비즈니스 모델을 제안하고 분석하여 펨토셀 산업에 대한 전반적인 시사점을 제시하고자 한다.

• Journal of KIISE:Software and Applications
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• v.37 no.5
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• pp.341-353
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• 2010

Mobile Internet Device (MID) allows users to flexibly use various forms of wireless internet such as Wi-Fi, GSM, CDMA, and 3G. Using such Internet, MID users can utilize application services. MID usage is expected to grow due to the benefits of portability, Internet accessibility, and other convenience. However, it has resource constraints such as limited CPU power, small memory size, limited battery life, and small screen size. Consequently, MIDs are not capable to hold large-sized complex applications and to process a large amount of data in memory. An effective solution to remedy these limitations is to develop cloud services for the required application functionality, to deploy them on the server side, and to let MID users access the services through internet. A major concern on running cloud services for MIDs is the potential problems with low Quality of Service (QoS) due to the characteristics of MIDs. Even measuring the QoS of such services is more technically challenging than conventional quality measurements. In this paper, we first identify the characteristics of MIDs and cloud services for MIDs. Based on these observations, we derive a number of quality attributes and their metrics for measuring QoS of mobile services. A case study of applying the proposed quality model is presented to show its effectiveness and applicability.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.1227-1230
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• 2005

최근 다양한 네트워크의 융합(Convergence) 추세에 따라 기존 PSTN 서비스도 인터넷에서 VoIP 형태로 제공이 되고 있다. 하지만 VoIP 서비스는 인터넷망을 이용하므로 부여된 발신번호 정보를 송출하지 않아 발신자의 위치 및 해당지역의 공공구조기관(PSAP)의 식별이 불가능하여 긴급서비스 지원을 위한 위치정보 제공을 못하는 문제점이 제기되었다. 최근 측위기술의 활용이 다양해지고 요구수준이 높아짐에 따라 실내에서의 신호 차폐 문제점을 극복할 수 있고, 높은 위치정확도 등을 제공하는 WLAN와 RFID 기술을 이용한 측위기술 연구가 활발하다. 따라서 본 논문에서는 Wi-Fi, RFID, GPS를 이용한 측위기술을 사용하여 무선이동통신 환경에서 VoIP 긴급서비스를 지원하기 위한 모델 제안과 각 구성요소에 대한 기능, 세부적인 지원 절차를 설명하고, 위치정보의 획득 및 처리를 위한 운용 시나리오에 관한 구체적 방안과 제안모델을 적용하기 위한 고려사항에 대한 분석결과를 제시한다. 그 결과 제안된 모델은 무선이동통신의 긴급서비스 설계시 적용이 기대된다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.18-25
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• 2014

To increase wireless capacity, the concurrent use of multiple wireless interfaces on different frequency bands, called aggregation, can be considered. In this paper, we focus on aggregation of multiple Wi-Fi interfaces with packet-level traffic spreading between the interfaces. Two aggregation schemes, link bonding and multipath TCP (MPTCP), are tested and compared in a dualband Wi-Fi radio system with their Linux implementation. Various test conditions such as traffic types, network delay, locations, interface failures and configuration parameters are considered. Experimental results show that aggregation increases throughput performance significantly over the use of a single interface. Link bonding achieves lower throughput than MPTCP due to duplicate TCP acknowledgements (ACKs) resulting from packet reordering and filtering such duplicate ACKs out is considered as a possible solution. However, link bonding is fast responsive to links' status changes such as a link failure. It is shown that different combinations of interface weights for packet spread in link bonding result in different throughput performance, envisioning a spatio-temporal adaptation of the weights. We also develop a mathematical model of power consumption and compare the power efficiency of the schemes applying different power consumption profiles.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.355-360
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• 2006

Function analysis and idea creation phase in Value Engineering(VE) Process is applied to manufacturing Industry for developing functions for elements of products, and in construction come to use various components like process, size of project, spaces as well as function itself due to multi-functional aspect. For this reason, VE applications to the construction industry are considered to be less frequent and efficient than to the manufacturing. To resolve this problem, a new technique of Function Integration Fast(HI FAST) and Hierarchical Value Engineering Concept Modules(HVECM) was made for practical integration and sequence of VE job Plan. Two types of function would be defined In this method, first and second function, during the job Plan process, and two function champions be selected for next creation phase process. For verification of consecutiveness of function analysis and idea creation phase for successful VE project implementation, this methodology was tested under design phase in office and IT Multi-functional building project. Make sure the successful application of this process with this method, need to develop the talent of VE experts and team members for process of function analysis and creation phase.