• 한국산업정보학회논문지
• /
• 제16권2호
• /
• pp.13-18
• /
• 2011

Security supports are a significant factor in mobile ad hoc networks. Especially in dynamic topologies, considering cluster, key management is essential to provide a secure system. Recently, Li-Liu proposed iD-based multiple key management scheme for cluster-based ad hoc networks. However, we found the security weakness of their scheme. In this paper, we analyze the security of Li-Liu's scheme and show that master secret key and fragment of the master secret key can be revealed to compromised CHs and nodes. Furthermore, we propose a solution to improve the scheme against disclosure of the share key and the master secret key even though system parameters are opened to compromised nodes and modify the Li-Liu's scheme fitted for a scalable networks. The improved IMKM scheme could be usefully applied in dynamic cluster-based MANETs such as the military battlefields, mobile marketplace and VANETs.

• Tribology and Lubricants
• /
• 제12권4호
• /
• pp.52-59
• /
• 1996

The results of the electrical contact conductivity of multi-contact spots accounting the surface roughness and the non-conductive films of different origins such as air, water, cutting oil, and machining oil are presented. The array of metal spheres compressed between two flat plates has been used for simulation of the contact behavior of multiple contact of solids, under normal loading. Measurement of electrical contact resistance has been made using the equipment providing the adequate accuracy in the range of micro Ohms. The data on electrical contact resistance have been compared with theoretical predictions using the multiple contact model of constriction resistance. The effect of single spot number and array on conductivity of contact has been evaluated. The results of the experiments show that the contact resistance are closely related to the number of loading cycles, form of surface roughness, and presence of non-conductive films that reduce the size of the real electrical contact spots.

• 지능정보연구
• /
• 제6권1호
• /
• pp.97-112
• /
• 2000

The basic idea of case-based reasoning is to solve a new problem using the previous problem-solving experiences. In this research we develop a case-based reasoning system for equipment malfunction diagnosis. We first divide the case base into clusters using the case-based clustering technique. Then we develop an appropriate case-based diagnostic system for each cluster. In other words for individual cluster a different case-based diagnostic system which uses different weights for attributes is developed. As a result multiple case-based reasoning system are operating to solve a diagnostic problem. In comparison to the performance of the single case-based reasoning system our system reduces the computation time by 50% and increases the accuracy by 5% point.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1999년도 추계종합학술대회 논문집
• /
• pp.456-459
• /
• 1999

In this paper, we propose a method of unconstrained handwritten numeral recognition using image dithering and multiple modular MLPs. The set of sample numeral patterns is subdivided into clusters which are extended by their radius. On each extended cluster, we constructed MLPs network as the expert recognizer of corresponding cluster. The gating network is also trained by an MLPs to weigh the outputs of expert MLPs. In training and test phase of the recognizer, we utilize the multiple dithered numeral images and the combination of the outputs for corresponding dithered images. Experimental results show that our recognition method works very well.

• 정보처리학회논문지A
• /
• 제13A권3호
• /
• pp.211-222
• /
• 2006

일반적인 비 공유 저장장치를 가진 시스템에서는 특정 컨텐츠에 대한 편향된(skewed) 요청 문제를 피할 수 없다. 본 논문에서는 비 공유 저장장치 모델로 설계/구현된 클러스터 기반의 스트리밍 서버에서 사용자의 편향된 컨텐츠 요청에 대처할 수 있고 스트리밍 서비스 중인 서버 또는 NS 카드에 문제가 생기더라도 스트리밍 서비스가 중단되지 않도록 다중 스트리밍 방법인 MDC(Multiple Description Coding)를 적용한 스트리밍 전송방법을 제안한다. 제안하는 방법은 클러스터 시스템에서 단일 세션으로 스트리밍 서비스를 제공하는 것이 아니라 MDC를 활용하여 다중 세션을 통한 스트리밍 서비스를 제공함으로써 모든 서버의 부하가 같아지고, 특정 서버에 문제가 발생하더라도 스트리밍 서비스가 끊어지지 않으면서 MDC의 특성인 적응형 서비스도 가능하게 되는 장점이 있다.

• The Journal of Asian Finance, Economics and Business
• /
• 제6권4호
• /
• pp.227-233
• /
• 2019

The study examines how business conditions, demand conditions and the role of government can influence the development of batik clusters in Pekalongan. This research is expected to be able to provide recommendations for both employers and local governments in order to help in optimizing the development of batik clusters. The research applied a quantitative research by engaging multiple regression analysis as an effort to understand the effect of the relationship between independent and dependent variables. In addition, this research was conducted in three largest batik clusters in Pekalongan, Indonesia namely batik cluster of Pasindon, Kauman, and Jenggot. These results indicate that business conditions positively affect the batik clusters development. It implies that the greater both business conditions in a cluster will lead the better the development. Indeed, the demand conditions also have an impact on the cluster development. This finding remarked that demand conditions are variable that need to be considered to development of batik cluster. Lastly, Government's role is confirmed that positively related to the Development of Batik Clusters. It implies that the more active the government's role in a cluster will have a good impact on the development of the cluster in certain area.

• 임상간호연구
• /
• 제20권1호
• /
• pp.123-133
• /
• 2014

Purpose: The purpose of the study was to investigate symptom clusters experienced by patients on hemodialysis and to identify relations between symptom clusters and quality of life. Methods: Data were collected from 127 patients at 10 local hemodialysis clinics. Symptoms were measured using 10-item physical symptom checklist as well as the Hospital Anxiety depression Scale. Quality of life was measured with the Satisfaction with Life Scale. Data were analyzed using factor analysis, Pearson correlation, and stepwise multiple regression. Results: The most frequently reported symptoms included fatigue, itching, depression, numbness/tingling, and insomnia. Four distinct symptom clusters were identified: cluster 1 was comprised of dry mouth, headache, nausea (gastrointestinal); cluster 2 of decreased appetite, insomnia (basic need); cluster 3 of itching, numbness/tingling (sensory-comfort); and cluster 4 of fatigue, depression (mood-vitality). Among the clusters, the 'basic need' cluster and 'mood-vitality' cluster had a significant negative association with quality of life. The 'mood-vitality' cluster, explained 17.4% of the variance in quality of life. Conclusion: The results of the study indicate that comprehensive symptom assessment provides better symptom management for patients on hemodialysis. Further studies are needed to verify symptom clusters identified in this study.

• Journal of Plant Biotechnology
• /
• 제30권3호
• /
• pp.241-244
• /
• 2003

Root cluster section culture, showing high efficient Protocorm-like body (PLB) formation capacity, were established in Doritaenopsis hybrids. Three types of root were obtained from excised shoots in 1/2MS medium containing different concentrations of NAA; \circled1normal roots, \circled2multiple roots and \circled3abnormal root clusters. Those were placed on 1/2MS medium supplemented with 0.5 mg/L thidiazuron for PLB regeneration. PLB regeneration rate was greater in root cluster section cultures (77.8%) compare to normal root tip cultures(30%). Number of PLBs regenerated from root cluster sections were counted over 11 per explant (5.3 per normal root tip).High frequency of PLB regeneration was achieved in root cluster section culture. This result can be used as an efficient method for clonal proliferation of Doritaenopsis hybrids.

• 아동학회지
• /
• 제35권2호
• /
• pp.103-115
• /
• 2014

This study explored the creative thinking styles of children according to cluster analysis and examined group differences in the gender of children. The participants consisted of 250 elementary school students living in Seoul, Korea. Data were analyzed by means of cluster analysis and ${\chi}^2$ test. The results from the cluster analysis based on the scores on the sub-factors of TTCT(Torrance Test of Creative Thinking) suggested the existence of four clusters('Non-creative', 'Divergent creative', 'Elaborate creative, 'Multiple creative'). Additionally, four clusters were found to be differentiated according to gender.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 ITC-CSCC -1
• /
• pp.176-179
• /
• 2002

In recent years, an increasing amount of computer network research has focused on the problem of cluster system in order to achieve higher performance and lower cost. The load unbalance is the major defect that reduces performance of a cluster system that uses parallel program in a form of SPMD (Single Program Multiple Data). Also, the load unbalance is a problem of MPP (Massive Parallel Processors), and distributed system. The cluster system is a loosely-coupled distributed system, therefore, it has higher communication overhead than MPP. Dynamic load balancing can solve the load unbalance problem of cluster system and reduce its communication cost. The cluster systems considered in this paper consist of P heterogeneous nodes connected by a switch-based network. The master node can predict the average execution time of tasks for each slave node based on the information from the corresponding slave node. Then, the master node redistributes remaining tasks to each node considering the predicted execution time and the communication overhead for task migration. The proposed dynamic load balancing uses execution time prediction to optimize the task redistribution. The various performance factors such as node number, task number, and communication cost are considered to improve the performance of cluster system. From the simulation results, we verified the effectiveness of the proposed dynamic load balancing algorithm.