• ETRI Journal
• /
• 제43권4호
• /
• pp.758-768
• /
• 2021

In this work, the secrecy of a typical wireless cooperative dual-hop non-orthogonal multiple access (NOMA)-enabled decode-and-forward (DF) relay network is investigated with the impact of collaborative and non-collaborative eavesdropping. The system model consists of a source that broadcasts the multiplexed signal to two NOMA users via a DF relay, and information security against the eavesdropper nodes is provided by a helpful jammer. The performance metric is secrecy rate and ergodic secrecy capacity is approximated analytically. In addition, a differential evolution algorithm-based power allocation scheme is proposed to find the optimal power allocation factors for relay, jammer, and NOMA users by employing different jamming schemes. Furthermore, the secrecy rate analysis is validated at the NOMA users by adopting different jamming schemes such as without jamming (WJ) or conventional relaying, jamming (J), and with control jamming (CJ). Simulation results demonstrate the superiority of CJ over the J and WJ schemes. Finally, the proposed power allocation outperforms the fixed power allocation under all conditions considered in this work.

• International Journal of Computer Science & Network Security
• /
• 제21권3호
• /
• pp.48-54
• /
• 2021

Security is an important issue for wireless communications and poses many challenges. Most security schemes have been applied to the upper layers of communications networks. Since in a typical wireless communication, transmission of data is over the air, third party receiver(s) may have easy access to the transmitted data. This work examines a new security technique at the physical layer for the sake of enhancing the protection of wireless communications against eavesdroppers. We examine the issue of secret communication through Rayleigh fading channel in the presence of an eavesdropper in which the transmitter knows the channel state information of both the main and eavesdropper channel. Then, we analyze the capacity of the main channel and eavesdropper channel we also analyze for the symbol error rate of the main channel, and the outage probability is obtained for the main transmission. This work elucidate that the proposed security technique can safely complement other Security approaches implemented in the upper layers of the communication network. Lastly, we implement the results in Mat lab

• 고려인삼학회:학술대회논문집
• /
• 고려인삼학회 2002년도 학술대회지
• /
• pp.145-158
• /
• 2002

Since immemorial time Panax ginseng has been known as therapeutic, tonic, prophylactic and restorative agent in ancient Korea, China and Tibet and at present time is also used as a food supplement by Western societies (6). Various ginseng preparations in a form of powders, teas, tinctures or extracts, very often mixed with other substances are recommended for attenuation of degenerative processes caused by aging or fatigue, as well as for treatment of various disorders and diseases in several organs (e.g. circulatory and nervous system, liver, kidney). One of the most commonly known properties of ginseng is its possibly positive influence on physical and mental performance and general well being. Because of these adaptogenic properties promoting vitality and resistance to stress ginseng is considered as an ergogenic aid. During almost 40 years in many laboratories attempts have been made to find out whether ginseng can be 'a remedy for today's problems'. The present work is focused on the results obtained in human studies and concerning an influence of ginseng root extracts on exercise and mental performance.

• 한국안전학회지
• /
• 제27권4호
• /
• pp.101-107
• /
• 2012

The statistics of industrial accident reported by ministry of Employment and Labor denoted a significant increase of musculoskeletal disorders(MSDs) after 1993, and showed the higher incident rate by 71.3% over the overall worker's disorders. Also, it was expected that Korean society will become the post-aged society in 2026 with 20.8% of elderly who is over 65 years old. The reports suggest possible problems caused by the older worker known to have reduced working ability than the young counterparts. On this basis, the goal of this study was to investigate the relationship between MSDs symptoms and work ability in the shipbuilding industry. To achieve this goal, this study distributed a questionnaire for total 1,244 shipbuilding employers, and used 910 employers' reports which revealed validity for this study. The questionnaire included the MSDs symptoms report developed by the Korean Occupational Safety and Health Association(KOSHA) and the work ability index(WAI) developed by Finnish Institute of Occupational Health(FIOH). Results showed no relationship between MSDs symptoms and age, years of work and exercise. Also, the work ability was increased until 44 years old, but it was decreased after that time because of the reduced physical capacity. Meanwhile, the years of work and exercise have positive correlation with work ability. However, the results revealed significant relationships between WAI and age, years of work, task characteristics and exercise. All together, the MSDs symptoms have a close relationship with the work ability in that the work ability of workers with the MSDs symptoms was reduced. This study may suggest the needs of more efforts and attention on the MSDs prevention to increase the work ability.

• 한국화재소방학회논문지
• /
• 제30권1호
• /
• pp.138-148
• /
• 2016

본 연구에서는 화재 현장에서의 소방진압 업무 적합도를 평가하기 위한 소방관 모의작업 프로토콜을 개발하였고 기존의 체력검정법과 평가 방식을 비교하였다. 본 연구에서 개발한 프로토콜은 모든 소방용 개인보호구를 착용한 채 복사열원 앞에서 3분 동안 걷는 동작을 포함한 총 여덟 가지 동작으로 구성되었으며 5분의 휴식을 사이에 두고 3회 반복되었다. 연구 결과로, 약 30분의 테스트 동안 소방관의 직장온과 심박수는 각각 $38.5^{\circ}C$, 185 bpm까지 상승하였다. 또한 총 소요시간과 연령보정치를 적용하지 않은 기초체력검정 결과는 유의하게 부적 상관관계를 보였다(r = -0.728, p < 0.05). 그러나 진압 경력이 긴 소방관일수록 총 소요시간은 길었던 반면, 총 소요시간과 생리적 부담 수준이 함께 고려된 평가 방식에서는 기초체력검정 결과보다 더 높은 점수를 얻었다. 이러한 결과는 단순하게 소요시간만을 이용한 평가는 생리적 서열부담을 무시할 수 있으며, 소방관 모의작업 프로토콜 이용 시 생리적 부담 수준을 함께 고려할 때에 소방진압 업무 적합도에 대한 보다 심층적인 평가가 가능함을 보여준다.

• World Technopolis Review
• /
• 제2권2호
• /
• pp.81-95
• /
• 2013

This paper seeks to build on previous work conducted by Porter, Devol, Florida, Bahrami and Evans, Wennberg and Lindqvist, and others contained in the literature, to construct a new way of looking at innovation cluster development. It seeks to describe the key elements contained in the research that serve as building blocks for innovation clustering, adding analysis dimensions that aim to further illuminate understanding of this process. It compares those building block characteristics to the innovation topography of U.S. urban centers, to shed light on a new framework through which urban innovation cluster formation can be considered. It identifies three building block analysis categories: 1) Technological Capability and Capacity (TCC); 2) Intellectual Propulsion Capacity (IPC); and 3) Structural Creative Inspiration (SCI). These three pillars form the architecture for creation of a Strategic Innovation Network (SIN), upon which clustering can be systematically analysed and built. The purpose of the SIN is to optimally organize and connect all available resources that include physical, financial, and human, such that innovation clustering is inspired, encouraged, nurtured, and ultimately constructed as fully functioning socio-economic organisms that provide both local and regional benefits. It is designed to aid both private enterprise and public policy leaders in their strategic planning considerations, and to enhance urban economic development opportunities.

• 한국통신학회논문지
• /
• 제39B권11호
• /
• pp.803-809
• /
• 2014

본 논문에서는 면허 사용자와 감청 사용자가 존재하는 인지무선 네트워크에서 릴레이 선택 기능을 이용한 물리 계층 보안 시스템을 제안하고 성능을 분석한다. 먼저 감청에 대한 보안성 확보를 위해 수신기 측에서의 채널 정보를 이용하는 기회적 최적 릴레이 선택 방법과 다중 안테나 다이버지시티를 이용하는 시스템을 제안한다. 이러한 시스템에서 인지무선 네트워크의 보안 outage 확률을 정의하고 수학적으로 정확한 확률 식을 유도한다. 아울러 송신전력에 제한이 없는 경우에 대한 점근적 outage 확률을 구한다. 수치 해석 결과를 제시함으로써 유도한 확률식의 정확성을 검증한다.

• 반도체디스플레이기술학회지
• /
• 제7권3호
• /
• pp.17-21
• /
• 2008

Application of flash memory in mobile and ubiquitous related devices is rapidly being increased due to its low price and high performance. In addition, some notebook computers currently come out into market with a SSD(Solid State Disk) instead of hard-drive based storage system. Regarding this trend, applications need to increase the storage capacity using multiple flash memory chips for larger capacity sooner or later. Flash memory based storage subsystem should resolve the performance bottleneck for writing in perspective of speed and lifetime according to its physical property. In order to make flash memory storage work with tangible performance, reclaiming of invalid regions needs to be controlled in a particular manner to decrease the number of erasures and to distribute the erasures uniformly over the whole memory space as much as possible. In this paper, we study the performance of flash memory recycling algorithms and demonstrate that the proposed algorithm shows acceptable performance for flash memory storage with multiple chips. The proposed cleaning method partitions the memory space into candidate memory regions, to be reclaimed as free, by utilizing threshold values. The proposed algorithm handles the storage system in multi-layered style. The impact of the proposed policies is evaluated through a number of experiments.

• Tuberculosis and Respiratory Diseases
• /
• 제68권3호
• /
• pp.125-139
• /
• 2010

Patients with chronic obstructive pulmonary disease (COPD) frequently complain of dyspnea on exertion and reduced exercise capacity, which has been attributed to an increase in the work of breathing and in impaired of gas exchange. Although COPD primarily affects the pulmonary system, patients with COPD exhibit significant systemic manifestations of disease progression. These manifestations include weight loss, nutritional abnormalities, skeletal muscle dysfunction (SMD), cardiovascular problems, and psychosocial complications. It has been documented that SMD significantly contributes to a reduced exercise capacity in patients with COPD. Ventilatory and limb muscle in these patients show structural and functional alteration, which are influenced by several factors, including physical inactivity, hypoxia, smoking, aging, corticosteroid, malnutrition, systemic inflammation, oxidative stress, apoptosis, and ubiquitin-proteasome pathway activation. This article summarizes briefly the evidence and the clinical consequences of SMD in patients with COPD. In addition, it reviews contributing factors and therapeutic strategies.

• 한국전기전자재료학회논문지
• /
• 제32권3호
• /
• pp.179-186
• /
• 2019

This work investigated the effects of different conductive agents on the electrochemical properties of anodes. SiOx possesses high theoretical capacity and shows excellent cycle performance; however, the low initial coulombic efficiency and poor electrical conductivity limit its applications in real batteries. In this study, electrodes were fabricated using two different conductive agents, and the resulting physical and electrochemical properties were analyzed. SEM observations confirmed the formation of a CNT conductive network throughout the electrodes, while the electrical conductivity contributed to the electrode was confirmed by impedance measurements. Thus, the electrode fabricated with the CNT conductive agent showed greater capacity and superior cycle performance than did the electrode fabricated using the DB conductive agent.