• Structural Engineering and Mechanics
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• v.70 no.4
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• pp.395-405
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• 2019

In the present work, the effects of cutting parameters on surface roughness parameters (Ra), tool wear parameters (VBmax), tool vibration (Vy) and material removal rate (MRR) during hard turning of AISI 4140 steel using coated carbide tool have been evaluated. The relationships between machining parameters and output variables were modeled using response surface methodology (RSM). Analysis of variance (ANOVA) was performed to quantify the effect of cutting parameters on the studied machining parameters and to check the adequacy of the mathematical model. Additionally, Multi-objective optimization based desirability function was performed to find optimal cutting parameters to minimize surface roughness, and maximize productivity. The experiments were planned as Box Behnken Design (BBD). The results show that feed rate influenced the surface roughness; the cutting speed influenced the tool wear; the feed rate influenced the tool vibration predominantly. According to the microscopic imagery, it was observed that adhesion and abrasion as the major wear mechanism.

• Journal of Environmental Science International
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• v.30 no.5
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• pp.399-406
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• 2021

The dissolution of ionized gas in dielectric barrier plasma, similar to the principle of ozone generation, is a major performance-affecting factor. In this study, the plasma gas dissolving performance of a gas mixing-circulation plasma process was evaluated using an experimental design methodology. The plasma reaction is a function of four parameters [electric current (X₁), gas flow rate (X₂), liquid flow rate (X₃) and reaction time (X₄)] modeled by the Box-Behnken design. RNO (N, N-Dimethyl-4-nitrosoaniline), an indictor of OH radical formation, was evaluated using a quadratic response surface model. The model prediction equation derived for RNO degradation was shown as a second-order polynomial. By pooling the terms with poor explanatory power as error terms and performing ANOVA, results showed high significance, with an adjusted R² value of 0.9386; this indicate that the model adequately satisfies the polynomial fit. For the RNO degradation, the measured value and the predicted values by the model equation agreed relatively well. The optimum current, gas flow rate, liquid flow rate and reaction time were obtained for the highest desirability for RNO degradation at 0.21 A, 2.65 L/min, 0.75 L/min and 6.5 min, respectively.

• Structural Engineering and Mechanics
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• v.76 no.5
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• pp.561-578
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• 2020

The present work addresses the surface integrity and chip morphology in finish hard turning of AISI D3 steel under nanofluid assisted minimum quantity lubrication (NFMQL) condition. The surface integrity aspects include microhardness, residual stress, white layer formation, machined surface morphology, and surface roughness. This experimental investigation aims to explore the feasibility of low-cost multilayer (TiCN/Al2O3/TiN) coated carbide tool in hard machining applications and to assess the propitious role of minimum quantity lubrication using graphene nanoparticles enriched eco-friendly radiator coolant based nano-cutting fluid for machinability improvement of hardened steel. Combined approach of central composite design (CCD) - analysis of variance (ANOVA), desirability function analysis, and response surface methodology (RSM) have been subsequently employed for experimental investigation, predictive modelling and optimization of surface roughness. With a motivational philosophy of "Go Green-Think Green-Act Green", the work also deals with economic analysis, and sustainability assessment under environmental-friendly NFMQL condition. Results showed that machining with nanofluid-MQL provided an effective cooling-lubrication strategy, safer and cleaner production, environmental friendliness and assisted to improve sustainability.

• Asian Journal for Public Opinion Research
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• v.11 no.4
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• pp.274-303
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• 2023

The third-person perception phenomenon can consistently be found in opinion poll news, but it remains unknown what determines the degree of the third-person perception (TPP) about specific election poll news. We investigated how respondents' preferred candidate's status in the poll affects the perceived impact of polling news on both themselves (PMI1) and on others (PMI3) as well as TPP (PMI3 - PMI1). We also examined the effect of subjective political knowledge and the perceived level of political knowledge of others on TPP. An online experiment was conducted in the context of a gubernatorial election in South Korea, in which the leading candidate in the poll and the question order (self-question first vs. other-question first) were manipulated. The results indicated that PMI1 and PMI3 were greater when the respondent's preferred candidate was leading in the poll. TPP did not differ depending on subjective knowledge, but it was greater when the others were non-experts (vs. experts). Lastly, question order was found to be a method factor that affected both PMI1 and PMI3. The theoretical and practical implications of these findings are discussed.

• Structural Engineering and Mechanics
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• v.88 no.6
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• pp.521-533
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• 2023

In the present study, the finite volume method is applied for the thermal performance prediction of the natural ventilation system using vertical solar chimney whereas, design parameters are optimized through the response surface methodology (RSM). The computational simulations are performed for various parameters of the solar chimney such as absorber temperature (40≤T_abs≤70℃), inlet temperature (20≤T₀≤30℃), inlet height of (0.1≤h≤0.2 m) and chimney width (0.1≤d≤0.2 m). Analysis of variance (ANOVA) was carried out to identify the design parameters that influence the average Nusselt number (Nu) and mass flow rate (ṁ). Then, quadratic polynomial regression models were developed to predict of all the response parameters. Consequently, numerical and graphical optimizations were performed to achieve multi-objective optimization for the desired criteria. According to the desirability function approach, it can be seen that the optimum objective functions are Nu=25.67 and ṁ=24.68 kg/h·m, corresponding to design parameters h=0.18 m, d=0.2 m, T_abs=46.81℃ and T₀=20℃. The optimal ventilation flow rate is enhanced by about 96.65% compared to the minimum ventilation rate, while solar energy consumption is reduced by 49.54% compared to the maximum ventilation rate.

• Steel and Composite Structures
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• v.50 no.2
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• pp.159-181
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• 2024

In the present study, the effect of geometrical parameters of two different types of aluminum thin-walled structures on energy absorption under three-bending impact loading has been investigated experimentally and numerically. To evaluate the effect of parameters on the specific energy absorption (SEA), initial peak crushing force (IPCF), and the maximum crushing distance (δ), a design of experiment technique (DOE) with response surface method (RSM) was applied. Four different thin-walled structures have been tested under the low-velocity impact, and then they have simulated by ABAQUS software. An acceptable consistency between the numerical and experimental results was obtained. In this study, statistical analysis has been performed on various parameters of three different types of tubes. In the first and the second statistical analysis, the dimensional parameters of the cross-section, the number of holes, and the dimensional parameter of holes were considered as the design variables. The diameter reduction rate and the number of sections with different diameters are related to the third statistical analysis. All design points of the statistical method have been simulated by the finite element package, ABAQUS/Explicit. The final result shows that the height and thickness of tubes were more effective than other geometrical parameters, and despite the fact that the deformations of the cylindrical tubes were around forty percent greater than the rectangular tubes, the top desirability was relevant to the cylindrical tubes with reduced cross-sections.

• Journal of the Economic Geographical Society of Korea
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• v.10 no.4
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• pp.414-426
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• 2007

The purpose of this study is to analyze whether the spatial externalities of agglomeration economy of manufacturing has been changed or not, from 1991 to 2005. To find this spatial SUR model was used to consider covariance of each equation and it was estimated by 3SLS. This paper found that spatial externalities has been decreased and there is economy of scale in same sector. As a result, we can conclude that there is industrial specialization in region whereas interregional linkage are weaken. This finding supports the desirability of creating supra-regional agencies promoting interregional linkage because supra-regional agencies can internalize spatial externality of agglomeration economy.

• Journal of Environmental Science International
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• v.23 no.3
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• pp.359-368
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• 2014

The aim of our research was to apply experimental design methodology in the optimization of N, N-Dimethyl-4-nitrosoaniline (RNO, which is indictor of OH radical formation) degradation using gas mixing-circulation plasma process. The reaction was mathematically described as a function of four independent variables [voltage ($X_1$), gas flow rate ($X_2$), liquid flow rate ($X_3$) and time ($X_4$)] being modeled by the use of the central composite design (CCD). RNO removal efficiency was evaluated using a second-order polynomial multiple regression model. Analysis of variance (ANOVA) showed a high coefficient of determination ($R^2$) value of 0.9111, thus ensuring a satisfactory adjustment of the second-order polynomial multiple regression model with the experimental data. The application of response surface methodology (RSM) yielded the following regression equation, which is an empirical relationship between the RNO removal efficiency and independent variables in a coded unit: RNO removal efficiency (%) = $77.71+10.04X_1+10.72X_2+1.78X_3+17.66X_4+5.91X_1X_2+3.64X_2X_3-8.72X_2X_4-7.80X{_1}^2-6.49X{_2}^2-5.67X{_4}^2$. Maximum RNO removal efficiency was predicted and experimentally validated. The optimum voltage, air flow rate, liquid flow rate and time were obtained for the highest desirability at 117.99 V, 4.88 L/min, 6.27 L/min and 24.65 min, respectively. Under optimal value of process parameters, high removal(> 97 %) was obtained for RNO.

• Journal of Korean Academy of Nursing
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• v.28 no.2
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• pp.244-255
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• 1998

The purpose of this study was to verify the reliability and validity of the Rosenbaum self-control schedule (SCS) for assessing resourcefulness in Korea and to explore the simplified scale. The study subjects consisted of 787 adults in a community. The data was collected during the period from Oct. to Dec., 1995 and analyzed as Cronbach α, item correlation with total, Pearson correlation and factor analysis with varimax rotation using SAS. Results were as follows : The mean SCS score for this sample was 17.2 and there were statistical differences for gender(men, 13.1 ; women, 20.0) on the SCS scores. The cronbachα of SCS with 36 items was .74 and when simplified with 30 items, it's coefficient alpha was .78. The translated content of the SCS was validated by two nursing faculty members and one professor of psychology. Factor analysis revealed the most parsimonious structure was obtained when six factors were extracted and subsequently rotated via the varimax criterion. There was 40.2% of total communality variance in the SCS with 36 items. The total communality variance was slightly increased to 43.4% with 30 items of the SCS. In order to reduce from 36 items to 30 items, the process excepted 6 items having low item correlation with total and low MSA(means of sampling adequacy) of factor analysis. According to factor analysis, there are six factors such as emotion control, impulse control, self-efficacy, coping with problems, pain control and satisfaction control, The SCS was found to have low, but statistically significant, correlations with social desirability and helplessness. From the above results, it can be concluded that the reliability of the SCS(inherent and simplified) was a acceptable level and its validity was reasonable when comparing it with other validity studies. To determine the usefulness the simplified scale, further study is necessary to simultaneously compare and analyze both scales for stability.

• 한국디지털정책학회:학술대회논문집
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• 2004.11a
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• pp.55-73
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• 2004

The Internet is a wonderland that can be enjoyed by the young, old, and those in-between. It is also a vast commercial market where many contracts are formed every second. The Internet and E-Commerce have created new situations that have generated sweeping proposals for fundamental changes in contract law. During the first half of the 20th Century. when many businesses expanded their geographic scope, there was a tremendous desire for uniform treatment of contracts for the sale of goods throughout the U.S.A. and the whole world. That same dynamic is now occurring in E-Commerce. There is a general recognition of the desirability of uniform contract law to govern E-commerce, but to date that does not exist, though there are extensive proposals for reform of contract law on the Internet. E-Commerce is currently plagued by some of the same problems that led to the passage of the UCC. In the absence of uniform legislation, state-by-state differences are inevitable with respect to E-Commerce. State-by-state differences in E-Commerce contract law is widely viewed as undesirable. To deal with this problem, a number of uniform bills have been proposed including UCITA, UETA, and revisions to Article 2 of the UCC (Subpart B). The thrust of these uniform acts is to create legal parity between paper records and electronic records. There is considerable resistance by consumer groups to this parity and progress towards Passage of UCITA, UETA, and revised Article 2 has been slow. The UCITA covers licenses of computer software but does not cover the sale oil goods on the Internet. The scope of the UCITA includes computer software. multimedia interactive products, computer data and databases, and Internet and online information, The UETA deals comprehensively with E-Commerce and contract law. The UCC covers the sale of goods, which does not necessarily involve E-Commerce. The basic principles of contract law are modified to deal with Internet transactions. Intent is inferred from the operations of electronic agents and "signatures" can occur with a response to an invitation to click to accept.