Selfish attacks and detection in cognitive radio Ad-Hoc networks

Minho Jo,Longzhe Han,Dohoon Kim,In, H. P. IEEE 2013 IEEE network Vol.27 No.3

<P>Cognitive radio is an opportunistic communication technology designed to help unlicensed users utilize the maximum available licensed bandwidth. Cognitive radio has recently attracted a lot of research interest. However, little research has been done regarding security in cognitive radio, while much more research has been done on spectrum sensing and allocation problems. A selfish cognitive radio node can occupy all or part of the resources of multiple channels, prohibiting other cognitive radio nodes from accessing these resources. Selfish cognitive radio attacks are a serious security problem because they significantly degrade the performance of a cognitive radio network. In this article we identify a new selfish attack type in cognitive radio ad-hoc networks and propose an easy and efficient selfish cognitive radio attack detection technique, called COOPON, with multichannel resources by cooperative neighboring cognitive radio nodes.</P>

Theory for plasticity of face-centered cubic metals

Jo, Minho,Koo, Yang Mo,Lee, Byeong-Joo,Johansson, Bö,rje,Vitos, Levente,Kwon, Se Kyun National Academy of Sciences 2014 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.111 No.18

<P>The activation of plastic deformation mechanisms determines the mechanical behavior of crystalline materials. However, the complexity of plastic deformation and the lack of a unified theory of plasticity have seriously limited the exploration of the full capacity of metals. Current efforts to design high-strength structural materials in terms of stacking fault energy have not significantly reduced the laborious trial and error works on basic deformation properties. To remedy this situation, here we put forward a comprehensive and transparent theory for plastic deformation of face-centered cubic metals. This is based on a microscopic analysis that, without ambiguity, reveals the various deformation phenomena and elucidates the physical fundaments of the currently used phenomenological correlations. We identify an easily accessible single parameter derived from the intrinsic energy barriers, which fully specifies the potential diversity of metals. Based entirely on this parameter, a simple deformation mode diagram is shown to delineate a series of convenient design criteria, which clarifies a wide area of material functionality by texture control.</P>

Mobile RFID Tag Detection Influence Factors and Prediction of Tag Detectability

Minho Jo,Hee Yong Youn,Si-Ho Cha,Hyunseung Choo IEEE 2009 IEEE SENSORS JOURNAL Vol.9 No.2

<P>Radio-frequency identification (RFID) readers are powered RF devices that communicate with tags (whether mobile or fixed) and read necessary information to be processed. A mobile RFID tag is detected by an RFID antenna. In a mobile RFID where the RFID tag is attached to a mobile object such as a vehicle, a human, or an animal, information is more difficult to detect than in the case where the tag is attached to a stationary object. Currently, deployment engineers and researchers use trial-and-error approaches to decide on the best conditions of the tag detection influence factors which affect tag detectability (detection rate). As expected, these approaches are time consuming. Even though mobile RFID systems have become widely used in industry and tag detection problems are crucial at deployment, very few researches on them have been conducted so far. Thus, a quick and simple method for finding tag detectability is needed to improve the traditional time consuming trial-and-error method. In this paper, we propose a unique approach ldquothe intelligent prediction method of tag detection rate using support vector machine (SVM).rdquo The intelligent method predicts the mobile RFID tag detectability instead of the trial-and-error experimental procedures. The simulation results of the proposed method are very comparable to the trial-and-error experimental approach. The proposed intelligent method gives a very high accuracy of mobile RFID tag detectability prediction and proves to be superior to the current method in time as well cost savings. The predicted tag detectability results can be used for analyzing mobile RFID tag detection influence factors and their conditions.</P>

RFID Tag Detection on a Water Content Using a Back-propagation Learning Machine

( Minho Jo ),( Chang-gyoon Lim ),( Emory W. Zimmers ) 한국인터넷정보학회 2007 KSII Transactions on Internet and Information Syst Vol.1 No.1

RFID tag is detected by an RFID antenna and information is read from the tag detected, by an RFID reader. RFID tag detection by an RFID reader is very important at the deployment stage. Tag detection is influenced by factors such as tag direction on a target object, speed of a conveyer moving the object, and the contents of an object. The water content of the object absorbs radio waves at high frequencies, typically approximately 900 MHz, resulting in unstable tag signal power. Currently, finding the best conditions for factors influencing the tag detection requires very time consuming work at deployment. Thus, a quick and simple RFID tag detection scheme is needed to improve the current time consuming trial-and-error experimental method. This paper proposes a back-propagation learning-based RFID tag detection prediction scheme, which is intelligent and has the advantages of ease of use and time/cost savings. The results of simulation with the proposed scheme demonstrate a high prediction accuracy for tag detection on a water content, which is comparable with the current method in terms of time/cost savings.

Morphology Engineering for Compact Electrolyte Layer of Solid Oxide Fuel Cell with Roll-to-Roll Eco-production

Minho Jo,Seongyong Kim,Changwoo Lee 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.2

Gadolinium-doped ceria (GDC) is sought-after as an electrolyte layer in solid oxide fuel cells because of its high ionic conductivity and low treatment temperature. Recently, some studies have been reported to produce a component layer of solid oxide fuel cell using a Roll-to-Roll (R2R) system because of its characteristics of the cost-effective and eco-friendly advantages. However, the brittleness and low density of GDC prevent it from being mass-produced via the R2R continuous process. Therefore, we attempted to improve the density of GDC-based multi-electrolyte layers through an optimized R2R calendaring process. The finite element method was employed to determine suitable materials for the calendering rolls and the maximum calendering pressure that would reduce the thickness and porosity of the coated electrolyte layer without producing cracks in the layer. The effect of the number of calendering processes on the thickness and porosity of the electrolyte layers was examined as well. Silicon and steel were observed to be best-suited as the materials for the top and bottom rolls, respectively. Moreover, the maximum permissible calendering pressure was determined to be 15 MPa, while the ideal number of calendering processes was found to be 5. Experimental observations using scanning electron microscopy confirmed that the optimized calendering process reduced the thickness and porosity of the coated electrolyte layers by 16.99% and 7.04%, respectively. Thus, our findings suggest that large-area, high-density GDC-based multi-electrolyte layers with smooth surfaces can be produced via the R2R process, which can enable mass production of SOFCs.

Device-to-device-based heterogeneous radio access network architecture for mobile cloud computing

Minho Jo,Maksymyuk, Taras,Strykhalyuk, Bohdan,Choong-Ho Cho IEEE 2015 IEEE wireless communications Vol.22 No.3

<P>The emerging heterogeneous mobile network architecture is designed for an increasing amount of traffic, quality requirements, and new mobile cloud computing demands. This article proposes a hierarchical cloud computing architecture to enhance performance by adding a mobile dynamic cloud formed by powerful mobile devices to a traditional general static cloud. A mobile dynamic cloud is based on heterogeneous wireless architecture where device-to-device communication is used for data transmission between user devices. The main advantage of the proposed architecture is an increase in overall capacity of a mobile network through improved channel utilization and traffic offloading from Long Term Evolution-Advanced to device-to-device communication links. Simulations show that the proposed architecture increases the capacity of a mobile network by up to 10 percent depending on the conditions and amount of offloaded data. The offloading probability is also evaluated by taking into consideration the number of devices in the cloudlet and the content matching values. We have gained insight into how content similarity affects offloading probability much more than the number of devices in a cloudlet.</P>

Resistance Control of an Additively Manufactured Conductive Layer in Roll-to-Roll Gravure Printing Systems

Minho Jo,Jongsu Lee,Seongyong Kim,Gyoujin Cho,Taik-Min Lee,이창우 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.3

Flexible pressure sensors, which are employed in robotic arms and electronic skin, are conventionally prepared using methods such three-dimensional printing, laser scribing, and spray coating. However, they are time-consuming and unsuitable for large-scale production. Thus, to overcome these limitations, roll-to-roll (R2R)-based fabrication techniques have been employed for low-cost mass production of flexible pressure sensors. Gravure printing is a promising R2R based technique, but it faces limitations in terms of ink-flow and printing defects causing short circuit, which may affect the performance of printed electronic devices. In this study, we analyzed the effects of printing conditions, web speed, tension, and nip pressure on the drag-out tail defects and conductance in the gravel printing process. We statistically optimized the optimal conditions to obtain minimum drag-out tail defects and conductance using a Box–Behnken design. We also fabricated two flexible pressure capacitive sensors using the conductive patterns to verify optimal conditions. Our results showed that the resistance decreased with increasing web speed, tension, and nip pressure, whereas the drag-out tail increased with increasing tension and nip pressure and decreasing web speed. Additionally, under the optimal conditions, the resistance and drag-out tail severity were improved by 74% and 53%, respectively, over those of the conventionally printed pattern. Finally, using the two flexible pressure capacitive sensors, we showed that the sensor using the conductive pattern had a higher sensitivity after optimization.

국내 정신건강의학과 의사의 전자 소통, 소셜 미디어 사용 현황과 지침 개발을 위한 예비연구

조민호(Minho Jo),이원혜(Wonhye Lee),황태연(Tae-Yeon Hwang) 대한사회정신의학회 2020 사회정신의학 Vol.25 No.1

목 적 : 소셜 미디어 등 웹서비스의 사용이 증가하며 임상 현장에서 의사-환자 관계에도 영향을 끼치고 있다. 이러한 상황에서 정신건강 의학과 의사들의 환자와의 전자 소통, 소셜 미디어 사용 현황을 알아보고 의료 정보의 제공과 소통의 기회를 확대하고 부작용을 최소화하기 위한 올바른 소셜 미디어의 사용에 관한 가이드라인 개발을 위하여 조사를 진행했다. 방 법 : 정신건강의학과 의사를 대상으로 설문지를 배포하였고 총 243명의 설문지가 수거됐다. 설문지에는 환자나 타인과 이메일 또는 문자 메시지 소통, 소셜 미디어 사용 및 개인정보 접근 제한 등과 환자와의 온라인 소통에 대한 가이드라인의 필요성 등이 포함됐다. 설문지 문항에 대한 기술통계분석과 연령별, 경력별, 근무지 형태별 차이를 분석했다. 결 과 : 응답자의 31.3%가 환자와 이메일로 소통하였고 이 중 5.3%만이 서면 동의를 받았다. 환자와 문자 메시지로 소통한다는 응답자는 39.1%였다. 반면 환자로부터는 이메일 소통 요청을 45.7%가 받고 있었다. 응답자의 26.7%는 환자의 사적인 정보를 인터넷으로 검색 하고 있었고 온라인 포스팅을 하고 있는 응답자는 51.0%였으나 20.2%는 개인정보 접근 제한을 전혀 하지 않았다. 개인정보 접근 제한은 연령대별로 차이가 있었다. 응답자의 83.5%가 학회나 협회 차원의 전자 소통, 소셜 네트워킹 등 온라인 상 환자와의 소통에 관한 가이드라인이 필요하다고 응답했다. 결 론 : 본 연구를 통하여 정신건강의학과 의사들이 임상현장에서 환자와 많은 전자 소통이나 소셜 미디어 사용을 하지 않고 있으나, 환자들의 소통 욕구는 증가하고 있었고, 개인정보 보호와 비밀 유지, 정확한 의료 정보교환 등을 위해 향후 가이드라인을 개발하고 준수할 필요성이 있음을 알 수 있었다. Objectives : The use of social media and other web services is increasing, and it is affecting doctor-patient relationships at the clinical situation. Under these circumstances, this research was conducted to investigate the Korean psychiatrists’ usage of social media, electronic communication with patients and colleagues and to develop guidelines to prevent possible negative effects. Methods : The questionnaire included e-mail or text messaging with patients or others, social media usage and privacy restrictions, and the need for guidelines for online communication with patients. The questionnaire was distributed through on-off line to psychiatrists and a total of 243 replies questionnaires were collected. Descriptive statistical analysis was conducted on the questions and additionally, non-parametric tests were conducted to analyze differences in age, career, and type of work for questionnaire questions. Results : 31.3% of the respondents communicated with patients via e-mail, and only 5.3 percent of them received written con-sent. 39.1% of the respondents reported that they communicate with patients via text messages. 26.7% of the them were searching for patients' personal information on the Internet. Before psychiatric interview, while 51.0% of respondents were posting online, 20.5% did not restrict access to personal information at all. Restrictions on personal information ac-cess differed by age group. 83.5% of the respondents reported that they need guidelines on online communication with patients. Conclusion : This study shows that psychiatrists in Korea are not so much using email and social media while they are communicating with their patients in the clinical setting even though they are observing the patients’ demands are increasing. Many psychiatrists agreed to develop and follow the guideline for the electronic communication and social media usage with patients and colleagues, which include privacy and personal data protection, medical information provision and transfer.

전산유체역학 기반 롤투롤 인쇄전자 시스템 건조 공정의 사행 거동 분석

조민호(Minho Jo),오효근(Hyogeun Oh),전호진(Hojin Jeon),최정배(Joungbae Choi),이창우(Changwoo Lee) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.5

롤투롤 시스템 건조 스팬의 건조 메커니즘 해석을 통한 소재 온도 분포 예측

조민호(Minho Jo),노재현(Jaehyun Noh),전호진(Hojin Jeon),오부국(Bukuk Oh),조규진(Gyoujin Cho),권신(Sin kwon),이창우(Changwoo Lee) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.6