• Journal of the Korea Society of Computer and Information
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• v.20 no.4
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• pp.77-85
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• 2015

Recently, wireless sensor network(WSN) have been used in various fields to implement ubiquitous computing environment. WSN uses small, low cost and low power sensors in order to collect information from the sensor field. This paper proposes a clustering algorithm for energy efficiency of sensor nodes. The proposed algorithm is based on conventional LEACH, the representative clustering protocol for WSN and it prolongs network and nodes life time using sleep technique and changable transmission mode. The nodes of the proposed algorithm first calculate their clustering participation value based on the distance to the neighbor nodes. The nodes located in high density area will have clustering participation value and it can turn to sleep mode. Besides, proposed algorithm can change transmission method from conventional single-hop transmission to multi-hop transmission according to the energy level of cluster head. Simulation results show that the proposed clustering algorithm outperforms conventional LEACH, especially non-uniformly deployed network.

• Journal of the Korea Society for Simulation
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• v.17 no.3
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• pp.27-34
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• 2008

Wireless sensor networks are comprised of sensor nodes with resource-constrained hardware. Nodes in the sensor network without adequate protection may be compromised by adversaries. Such compromised nodes are vulnerable to the attacks like false reports injection attacks and false data injection attacks on legitimate reports. In false report injection attacks, an adversary injects false report into the network with the goal of deceiving the sink or the depletion of the finite amount of energy in a battery powered network. In false data injection attacks on legitimate reports, the attacker may inject a false data for every legitimate report. To address such attacks, the probabilistic voting-based filtering scheme (PVFS) has been proposed by Li and Wu. However, each cluster head in PVFS needs additional transmission device. Therefore, this paper proposes a fuzzy logic-based false report detection method (FRD) to mitigate the threat of these attacks. FRD employs the statistical en-route filtering scheme as a basis and improves upon it. We demonstrate that FRD is efficient with respect to the security it provides, and allows a tradeoff between security and energy consumption, as shown in the simulation.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.2 s.150
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• pp.316-325
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• 2006

The colors of apparel are getting more important to give the differentiated character on fiber and fabrics. This study was to extract the favorable colors that become to facial color types. Research was carried out to classify the facial colors into several similar facial color groups. With JX-777, 2 points of face: forehead and cheek, were measured and classified into 3 facial color types. Sample size was 418 Korean adult males and other 15 of new males subjects. New chosen 3 subjects who had the classified facial color types, wore silver gown and black hat on his head to minimize the interaction of the clothe color an hair. The 40 standardized color samples were used to extract the favorable colors. 187 respondents answered the degree of becomingness of color samples on 3 facial color types. Data were analyzed by K-means cluster analysis, ANOVA and Duncan multiple range test using SPSS Win. 12. Findings were as follows: 1. 418 subjects who had YR colors were classified into 3 kinds of facial color groups. Type 1 was 4.59YR 5.89/5.12, Type 2 was 5.61 YR 5.41/4.79 and Type 3 was 4.38YR 6.49/4.89 respectively. 2. Favorable colors for Type 1 were 2 colors that belonged to ' a ' group from among colors that were divided into a, b, c group and 18 colors that belonged to ' a ' group from among colors that were divided into a, b group by Duncan post hoc test. 3. Type 2 showed that this type had many unfavorable colors. Unfavorable colors were 16 colors that belonged to ' c ' by Duncan test. 5. Favorable colors for Type 3 were 14 colors that belonged to ' a ' from among colors that were divided into a, b, c and 16 colors that belonged to ' a ' from among colors that were divided into a, b by Duncan test.

• Human Ecology Research
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• v.53 no.5
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• pp.489-502
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• 2015

This study identifies the relation between recognition relatively deprivation and consumption patterns. The data used were the seventh Korea Welfare Panel Study (KOWEPS). The final sample of 1,597 households was selected based on several sampling steps standard weights suggested by KOWEPS were applied. The final sample was subdivided into household recognizing relatively deprivation (51.7%) and non-household recognizing relatively deprivation (48.3%) per level of subjective income and objective income. We derived six consumption patterns from the cluster analysis as per consumption ratio: transportation dominant consumption pattern, essential consumption pattern, other dominant consumption pattern, care attention consumption pattern, private transfer consumption pattern, and education dominant consumption pattern. The results of this study are as follows. The analysis of the determinants of recognizing relatively deprivation in regards to question one found that the household was likely to be relatively deprived when: the head of a household was older, a household had a dual income, children and more total assets then those assessed 1 year ago compared to household living conditions, result of comparing the consumption patterns difference between household recognizing relatively deprivation and non-household recognizing relatively deprivation indicated that household recognizing relatively deprivation was more likely to belong to the transportation dominant consumption pattern, other dominant consumption pattern, and private transfer consumption pattern. The multinomial logistic analysis conducted to understand the determinants affecting the consumption patterns of household recognizing relatively deprivation indicated differences in demographic characteristics, household-related variables, financial variables and perception of economic conditions.

• International Journal of Fluid Machinery and Systems
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• v.2 no.2
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• pp.165-171
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• 2009

We developed a 'multi-point vibration acceleration method' for accurately predicting the cavitation intensity in pumps. Pressure wave generated by cavitation bubble collapse propagates and causes pump vibration. We measured vibration accelerations at several points on a casing, suction and discharge pipes of centrifugal and mixed-flow pumps. The measured vibration accelerations scattered because the pressure wave damped differently between the bubble collapse location and each sensor. In a conventional method, experimental constants are proposed without evaluating pressure propagation paths, then, the scattered vibration accelerations cause the inaccurate cavitation intensity. In our method, we formulated damping rate, transmittance of the pressure wave, and energy conversion from the pressure wave to the vibration along assumed pressure propagation paths. In the formulation, we theoretically defined a 'pressure propagation coefficient,' which is a correlation coefficient between the vibration acceleration and the bubble collapse pressure. With the pressure propagation coefficient, we can predict the cavitation intensity without experimental constants as proposed in a conventional method. The prediction accuracy of cavitation intensity is improved based on a statistical analysis of the multi-point vibration accelerations. The predicted cavitation intensity was verified with the plastic deformation rate of an aluminum sheet in the cavitation erosion area of the impeller blade. The cavitation intensities were proportional to the measured plastic deformation rates for three kinds of pumps. This suggests that our method is effective for estimating the cavitation intensity in pumps. We can make a cavitation intensity map by conducting this method and varying the flow rate and the net positive suction head (NPSH). The map is useful for avoiding the operating conditions having high risk of cavitation erosion.

• The Journal of the Korea Contents Association
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• v.12 no.11
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• pp.88-99
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• 2012

Korean Film Council (KOFIC) is entrusted by the Ministry of Culture, Sports and Tourism, Republic of Korea, aiming to support and promote Korean films. With the government's policy for balanced regional development, KOFIC head office will be relocated to Busan. Busan is famous for the Busan International film Festival and their effort for Korean film industry. Until now, the Korean film industry is concentrated on the Seoul metropolitan areas. With the relocation of KOFIC, it is the time for KOFIC to recognize and promote and Busan as the Second key Cluster of Korean film industry. With the cooperation with Busan Film Commission, KOFIC needs to set up the new promotion plan for Korean film industry for future including building new film production studio, raising regional film production fund, and scouting new talented filmmakers.

• Journal of the Korean Home Economics Association
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• v.12 no.2
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• pp.621-631
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• 1974

The objective of the study was to obtain standard sizes of body of the high school girls for designing clothes and developing pattern grading of clothes. In 1972, 342 students, selected by the stratified cluster random sampling method, at three high schools in Seoul were measured on forty-one items by the R. Martin method. Statistical techniques of mean, standard deviation, coefficient variable, maximum and minimum, range, t-test were utilized to analyze the data. The findings of the study were as follows ; 1. No differences were found among the age groups in the all measured variables. 2. Stature, bust girth, hip girth, acromion width, posterior waist girth/stature ratio of the high school girls were significantly smaller than those sizes of adult women. This result implies that those sizes will be increased as the students grow up. But upper arm girth, upper arm girth/bust girth ratio, and thigh girth/bust girth ratio were bigger than those sizes of adult women. Waist girth, thigh girth, total head height/stature ratio, acromion width/stature ratio, and foot length/stature ratio were nearly similiar to those of adult women. 3. According to the result of t-test, waist breadth, spinailiaca anterior height/stature ratio, thigh girth/bust girth ratio, and thigh/hip girth ratio of the 15 year old group were significantly different from those of the 16 year old group at the level of 0.05. Bust girth, weight, foot breadth, posterior croth length, and cervical height/stature ratio of the 16 year old group were significantly different from those of the 17 year old group at the level of 0.01. Hip girth, upper arm girth, waist breadth/stature ratio, and neck base girth/bust girth ratio of the 16 year old group were significantly different from those of the 17 year old group at the level of 0.05.

• Journal of the Korea Society of Computer and Information
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• v.19 no.6
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• pp.49-59
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• 2014

Recently, wireless sensor networks(WSNs) are widely used for intrusion detection and ecology, environment, atmosphere, industry, traffic, fire monitoring. In this paper, an energy efficient clustering algorithm is proposed. The proposed algorithm forms clusters uniformly by selecting cluster head that optimally located based on receiving power. Besides, proposed algorithm can induce uniform energy consumption regardless of location of nodes by multi-hop transmission and MST formation with limited maximum depth. Through the above, proposed algorithm elongates network life time, reduces energy consumption of nodes and induces fair energy consumption compared to conventional LEACH and HEED. The results of simulation show that the proposed clustering algorithm elongates network life time through fair energy consumption.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.10
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• pp.801-807
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• 2013

WSN consists of hundreds to thousands of sensor nodes. In order to solve the problem of energy consumption imbalance cluster head is reelected in every round, while node authentication scheme is utilized for secure communication. However, re-clustering increases the overhead of sensor nodes and during the node authentication phase the frequent AREQ/AREP message exchange also increases the overhead. Therefore, a secure and energy efficient protocol, by which overhead of sensor nodes is reduced and long time communication is achieved, is required for wireless sensor network. In this paper, an energy efficient and reliable IDE-LEACH protocol for WSN is proposed. The proposed protocol is prolongs networks lifetime about average 20% compared to the LEACH-based protocols and all attending nodes in communication form BS authentication consisted of trusted nodes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.5
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• pp.632-639
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• 2012

Ad-hoc networks can be used various environment, which it is difficult to construct infrastructures, such as shadowing areas, disaster areas, war area, and so on. In order to support to considerable and various wireless services, more spectrum resources are needed. However, efficient utilization of the frequency resource is difficult because of spectrum scarcity and the conventional frequency regulation. Ad-hoc networks employing cognitive radio(CR) system that guarantee high spectrum utilization provide effective way to increase the network capacity. In conventional CR based ad-hoc network, it uses constant threshold value to detect primary user signal, so the results become not reliable. In this paper, to solve this problem, we apply adaptive threshold value to the CR based ad-hoc network, and adaptive threshold is immediately changed by SNR(Signal to Noise Ratio). From the simulation results, we confirmed that proposed algorithm has the greatly better detection probabilities than conventional CR based ad-hoc network.