• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.3
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• pp.210-219
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• 2003

A laminated evaporator performance simulation software has been developed and the performance characteristics have been examined with variation of important design parameters, number of plate ( $P_{N}$), plate inner height ( $P_{h}$), Plate thickness ( $p_{t}$) and plate wetted Perimeter ( $P_{wl}$ ). To confirm the program, performance experiment was carried out for two different evaporators. The simulation results matched with experiments within $\pm$10%. Through the parametric studies, $P_{N}$ was shown to be most influential. The $P_{N}$, $P_{h}$ and $P_{wl}$ had a maximum cooling capacity point in the calculation range. In case of $P_{t}$, the smaller was the better.ter.etter.ter.

• Journal of the Korea Safety Management & Science
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• v.12 no.3
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• pp.333-339
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• 2010

Data mining is the process of finding and analyzing data from a big database and summarizing it into useful information for a decision-making. A variety of data mining techniques have been being used for wide range of industries. One application of those is especially so for gathering meaningful information from process data in manufacturing factories for quality improvement. The purpose of this paper is to provide a methodology to improve manufacturing quality of fuel tanks which are auto-parts. The methodology is to analyse influential attributes and establish a model for optimal manufacturing condition of fuel tanks to improve the quality using decision tree, association rule, and feature selection.

• ETRI Journal
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• v.38 no.1
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• pp.52-61
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• 2016

A microblog is a service typically offered by online social networks, such as Twitter and Facebook. From the perspective of information dissemination, we define the concept behind a spreading matrix. A new WeiboRank algorithm for identification of key nodes in microblog networks is proposed, taking into account parameters such as a user's direct appeal, a user's influence region, and a user's global influence power. To investigate how measures for ranking influential users in a network correlate, we compare the relative influence ranks of the top 20 microblog users of a university network. The proposed algorithm is compared with other algorithms - PageRank, Betweeness Centrality, Closeness Centrality, Out-degree - using a new tweets propagation model - the Ignorants-Spreaders-Rejecters model. Comparison results show that key nodes obtained from the WeiboRank algorithm have a wider transmission range and better influence.

• Journal of Families and Better Life
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• v.17 no.2
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• pp.105-120
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• 1999

The purpose of this study was to examine dimensions related to effective managerial actions in association with effects of resourcefulness personal and managerial communications and condition s for effective home management on the basis of managerial process. Including elements of managerial process conditions for effective home management were divided into the four factors performance-condition dichotomy timing high level and middle range. In conclusion first the managerial process for effective management can be classified into the four conditions related to each other. That was termed as 'conditions for effective home management' Second the most influential variables on conditions for effective home management were personal and managerial communication. The four conditions for effective home management need to include communicaion. Third resuorcefulness was a crucial factor in relation to home management resources division. It is recommedned that resuorcefulness needs to de elop managerial actions of housewives.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.25 no.4
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• pp.312-326
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• 2021

The prey-predator model is one of the most influential mathematical models in ecology and evolutionary biology. In this study, we considered a modified prey-predator model, which describes the rate of change for each species. The effects of modifications to the classical prey-predator model are investigated here. The conditions required for the existence of the first integral and the stability of the fixed points are studied. In particular, it is shown that the first integral exists only for a subset of the model parameters, and the phase portraits around the fixed points exhibit physically relevant phenomena over a wide range of the parameter space. The results show that adding coupling terms to the classical model widely expands the dynamics with great potential for applicability in real-world phenomena.

• Advances in nano research
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• v.7 no.4
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• pp.265-275
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• 2019

In this work, the effect of size on the axial buckling behavior of single-layered graphene sheets embedded in elastic media is studied. We incorporate Eringen's nonlocal elasticity equations into three plate theories of first order shear deformation theory, higher order shear deformation theory, and classical plate theory. The surrounding elastic media are simulated using Pasternak and Winkler foundation models and their differences are evaluated. The results obtained from different nonlocal plate theories include the values of Winkler and Pasternak modulus parameters, mode numbers, nonlocal parameter, and side lengths of square SLGSs. We show here that axial buckling behavior strongly depends on modulus and nonlocal parameters, which have different values for different mode numbers and side lengths. In addition, we show that in different nonlocal plate theories, nonlocality is more influential in first order shear deformation theory, especially in certain range of nonlocal parameters.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.1
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• pp.41-51
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• 2018

Downwash from helicopter rotor blades and external winds from various maneuvering make an unguided rocket change its trajectory and range. For the prediction of the trajectory and range, it is essential to consider the downwash effect. In this study, an algorithm was developed to calculate 6-Degree-Of-Freedom(6 DOF) forces and moments exerting on the rocket, and total flight trajectory of a 2.75-inch unguided rocket in a helicopter downwash flow field. Using Actuator Disk Model(ADM) analysis result, the algorithm could analyze the entire trajectory in various initial launch condition such as launch angle, launch velocity, and external wind. The algorithm that considered the interference between a fuselage and external winds could predict the trajectory change more precisely than inflow model analysis. Using the developed algorithm, the attitude and trajectory change mechanism by the downwash effect were investigated analyzing the effective angle of attack change and characteristics of pitching stability of the unguided rocket. Also, the trajectory and range changes were analyzed by considering the downwash effect with external winds. As a result, it was concluded that the key factors of the rocket range change were downwash area and magnitude which effect on the rocket, and the secondary factors were the dynamic pressure of the rocket and the interference between a fuselage and external winds. In tailwind case which was much influential on the range characteristics than other wind cases, the range of the rocket rose as increasing the tailwind velocity. However, there was a limit that the range of the rocket did not increase more than the specific tailwind velocity.

• Journal of Korean Academy of Nursing
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• v.31 no.6
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• pp.1012-1020
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• 2001

The purpose of this study was to describe physical health and depression status, as well as to assessing factors that influence the physical health status. Method: The data was collected from July to August 2000. Study participants were 252 community-dwelling elderly who were recruited from 10 senior centers located in Seoul, Korea. Their physical health status was measured using the Physical Health Status Measurement Scale developed by Choi and Jung (1991), and depression was measured using BDI-II developed by Beck et al. (1996). Results: 1) The physical health status score was 4.00 $\pm$0.68 (range :1- 5). The sub-dimension that showed the highest score was personal hygiene ability at 4.62$\pm$0.95, and the lowest score was sexual function at 2.20$\pm$1.38. 2. The depression score was 17.99+9.79 (range : 0-63). Regarding the sub-dimensions, the depression scores were higher in the domain of interest with sexuality, general weakness, difficulty in concentration, and fatigue. 3. Deeper levels of depression were correlated with a declining physical health status. 4. The most influential factor on physical health was depression, and the explaining variance was 31.68%. Conclusion: It is concluded that elder subjects in senior centers had fairly good physical health and self-care ability. Also, they did not have significantly high levels of depression. Therefor, health promotion of elderly, it is recommended that elder individuals should be regarded as a respectful and useful segment of our society. Along with this basic concept, there should be a social milieu that does not snow prejudice. Moreover, health care professionals should give more attention to helping the elderly achieve a minimal level of ALD, and, particularly, to raise sexuality and help energize the lives of elder individuals.

• Journal of the Korean Geotechnical Society
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• v.23 no.6
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• pp.67-76
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• 2007

Raining method has been widely used for preparing sand specimen because of its ability to reconstitute the homogeneous specimen with desired relative density and its reliability established by the numerous experiments on diverse influential factors. In conventional raining methods, adjustment of relative density is achieved by controlling the shutter porosity and the whole system is required to be re-adjusted to achieve the target relative density when the granular characteristics are changed. It is also observed from conventional methods that certain degrees of spatial variation in density exist and the limited range of relative density is reproduced. In this paper, raining system with porous plate is proposed. It is shown that the wide range of relative density can be achieved by controlling failing height only. This enhanced system is able to obviate the subtle control of shutter porosity and minimize the effect of falling distance, which in turn ensures the homogeneity of the specimen, especially for low relative density.

• Korean Journal of Child Studies
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• v.14 no.1
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• pp.167-177
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• 1993

The purpose of the present study to investigate relationships among family background factors (i. e. adolescents' sex, mother's educational level and employment status. family's SES, and family types), mother-adolescent communication patterns and ego-identity development of adolescents. The subjects were 169 mother-adolescent dyads living in Seoul. Statistical methods used for the data analysis were frequencies, percentiles, Mean, ANOVA, Duncan's multiple range test, Pearson's product-moment correlation, regression analysis, ANCOVA, and Cronbach's ${\alpha}$. The results were as follows: (1) Significant differences of the adolescents were between family's SES and open communication patterns, between family types and problematic communication patterns. (2) Significant differences of the mothers were between family's SES and open communication patterns, and among family's SES, mother's educational level and problematic communication patterns. (3) There were significant differences in ego-identity of adolescents according to family's SES. (4) There were significant relationships between mother-adolescent communication patterns and the ego-identity development of adolescents. (5) The most influential variable explaining adolescents' ego-identity development was found to be problematic communication patterns perceived by adolescents. Family background factors and mother's communication patterns were not found to have significant effects.