• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.338-343
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• 2001

Recently the steel parts used at automobiles are required to be used under high stress more than ever before in need of the weight down. To achieve this requirement of a high strength steel, it must be necessary to decrease inclusion content and surface defect as like decarburization, surface roughness etc., In this study, the surface conditions are measured to know the influence on fatigue properties by two cases of shot peening of two-stage shot peening and single-stage shot peening. And for this study, two kinds of spring steel(SAE 9254, DIN 50CrV4) are made. This study shows the outstanding improvement of fatigue properties at the case of two-stage shot peening in the rotary bending fatigue test and this is assumed to be from (1) on low stress condition, the single stage shot peening is not affected by nonmetallic inclusion under metal. (2) it is possible that the two-stage shot peening increases the fatigue life and the high stress, but, that is affected by nonmetallic inclusion under metal. (3) so far, beeasily 50CrV4 have made high stress. But, results also show fatigue failures originated at inclusion near surface, and this inclusion type is turned out to be a alumina of high hardness.

• Knowledge Management Research
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• v.16 no.3
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• pp.149-169
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• 2015

In this study, we try to understand the role of online social recommendation and the similarity of preferences between the recommender and the recommendee on consumer decisions in the framework of the two stage purchase decision-making process. Applying construal level theory to our context, we expect that the role of social recommendation and the similarity of preferences would vary over the stages in the two-stage decision making process. To test our hypotheses, we collected the data through an incentive compatible experiment, and analyzed the data with nested logit model. As a result, we found that the role of online social recommendation varies over the stages. Consumers take recommendation from similar others at the stage of consideration set formation, but no longer consider it at the stage of final choice. Consumers take recommendation from dissimilar others at the stage of consideration set formation. At the stage of final choice, however, consumers avoid choosing the option recommended by dissimilar others. The results of our study enrich the understanding about the role of social recommendation, and have implication to marketing practitioners who attempt to make online social recommendation system more efficient.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.145-150
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• 2003

The present study aims to optimize the performance of the Two-Stage Gas Gun by using the experimentally obtained data. RSM(Response Surface Method) was adopted in the optimization process to find the operating parameter than can maximize the projectile speed with the minimum number of tests. To decide the test points which results can consist of the response surface, 3$^{k}$ full factorial method was used, and the design variables were chosen with piston mass and 2$^{nd}$ driver fill pressure. The response surface was composed by nine test results and consequently the optimization was done with GENOCOP III, inherently GA code, in order to seek the optimal test point. The optimal test condition from the response surface was verified by the experiment. Results showed that the optimization process with response surface can successfully predict the test results fairly well. This study shows the possibility of performance optimization for the experimental facilities using numerical optimization algorithm.

• Journal of Korean Academy of Nursing Administration
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• v.1 no.2
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• pp.268-284
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• 1995

This study was designed to test effects of nursing ethics education (NEE) on moral reasoning and ethical decision making of subjects. This NEE that was teached for 10 hours course was composed of these : Nurses' ethical code, moral responsibility, Moral value and professional accountability, Respect for human life, General ethics, Theory and Norms of biomedical ethics, Ethical decision making model and Discussion about hypothetical ethical dilemmas Twenty-five senior student nurses were sampled from four year college of nursing from Nov. 3rd, 1993 to Nov. 24th, 1993. Data were collected through self-reported questionnaires included two kinds of tests. Rest's Defining Issues Test was adopted to measure the stage of moral development, which was classified with the stage 2 (instrumental relativist orientation), the stage 3 (interpersonal concordance), the stage 4 (law and order), the stage 5A (societal consensus), and the stage 5B (intuitional humanism), the stage 6 (universal ethical practice). In particular, the level of principled thinking (P) was measured by summing these scores of the stages 5A, 5B, and 6. The possible range of P is 0 to 95. As for measuring the levels of morality and nursing dilemma, Crisham's Nursing Dilemma Test was adopted. This test generated the morality score(MS) and the dilemma score (DS). The data were analyzed by t-test, ANOVA, Kruskal-Wallis test, Mc Nemar's test and Pearson correlation coefficients. The results were as follows ; 1. For the Moral Reasoning both before and after NEE, The Mean score of the stage 5A was significantly higher than that of other stages.(P=0.0001) Before NEE, the mean score of the stage 4 was significantly different from stage 2, 3, 5A, and after NEE, different from stage 2, 5B,6. 2. The analysis of change of moral development level revealed that the score of stage 4 increased after NEE.(P=0.0004) 3. The Effect of NEE for the mean score of 5A, 6, P after education was significantly different by birth place. 4. With regard to the five dilemmas postulated such as forcing medication performing cardiac pulmonary resuscitation, reporting a medication error, informing diagnosis to terminally ill adult, and providing new-nurse orientation, the mean score of the MS and the DS was no significant difference with general characteristics of the students. Effect of NEE morality score and dilemma score after education was no significant difference. 5. As for the correlations between moral reasoning and decision making, the score of the stage 2, 5A, 6, DS was positively correlated with the scores of before and after. Positive correlation was also observed between the scores of stage 2 and stage 4, stage 3 and 6. On the other hand, the score of P was negatively correlated with the scores of stage 2 and of stage 4 and of stage 5A. The score of the stage 5A was also negatively correlated with the score of the sge 6.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.7
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• pp.675-682
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• 2009

Instead of direct driving like BLDC, the induction principle is adopted as a driving one for planar stage. The stage composed of four linear induction motors put in square type is activated by two-axial forces; low-frequency attractive force and thrust force of the linear induction motors. Here, the modified vector control whose new inputs are q-axis current and dc current biased to three phase current instead of d-axis current or flux current is applied extensively to overall motion of the stage. For the developed system, the precision step test and the constant velocity test are tried to guarantee its feasibility for TFT-LCD pattern inspection. However, to exclude a discontinuity due to phase shift and minimize a force ripple synchronized with the command frequency, the initial system is revised to the antagonistic structure over the full degree of freedom. Concretely describing, the porous air bearings guide an air-gapping of the stage up and down and a pair of liner induction motors instead of single motor are activated in the opposite direction each other. The performances of the above systems are compared from trapezoid tracking test and sinusoidal test.

• The Journal of Advanced Prosthodontics
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• v.6 no.2
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• pp.126-132
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• 2014

PURPOSE. This study was conducted to evaluate the influence of the implant-abutment connection design and diameter on the screw joint stability. MATERIALS AND METHODS. Regular and wide-diameter implant systems with three different joint connection designs: an external butt joint, a one-stage internal cone, and a two-stage internal cone were divided into seven groups (n=5, in each group). The initial removal torque values of the abutment screw were measured with a digital torque gauge. The postload removal torque values were measured after 100,000 cycles of a 150 N and a 10 Hz cyclic load had been applied. Subsequently, the rates of the initial and postload removal torque losses were calculated to evaluate the effect of the joint connection design and diameter on the screw joint stability. Each group was compared using Kruskal-Wallis test and Mann-Whitney U test as post-hoc test (${\alpha}$=0.05). RESULTS. The postload removal torque value was high in the following order with regard to magnitude: two-stage internal cone, one-stage internal cone, and external butt joint systems. In the regular-diameter group, the external butt joint and one-stage internal cone systems showed lower postload removal torque loss rates than the two-stage internal cone system. In the wide-diameter group, the external butt joint system showed a lower loss rate than the one-stage internal cone and two-stage internal cone systems. In the two-stage internal cone system, the wide-diameter group showed a significantly lower loss rate than the regular-diameter group (P<.05). CONCLUSION. The results of this study showed that the external butt joint was more advantageous than the internal cone in terms of the postload removal torque loss. For the difference in the implant diameter, a wide diameter was more advantageous in terms of the torque loss rate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.10
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• pp.993-998
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• 2007

To verify the 2D or 3D positioning accuracy of a multi-axes stage is not easy, particularly, in the case the moving path of the stage is not linear. This paper is a study on a measuring method for the curved path accurately. A machine vision technique is used to trace the moving path of two-axes stage. To improve the accuracy of machine vision, a zoom lens is used for the 2D micro moving path. The accuracy of this method depends of the CCD resolution and array align accuracy with the zoom lens system. Also, a further study for software algorithm is required to increase the tracing speed. This technique will be useful to trace a small object in the 2D micro path in real-time accurately.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2196-2207
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• 2017

This paper presents a two-stage market auction model in a pool-based electricity market, which explicitly takes into account the system network security. The security network-constrained market auction model considers the use of corrective control to yield economically efficient actions in the post-contingency state, while ensuring a certain security level. Under this framework, the proposed model shows not only for quantifying the correlation between secure system operation and efficient market operation, but also for providing transparent information on the pricing system security for market participants. The two-stage market auction procedure is formulated using Benders decomposition (BD). In the first stage, the market participants bid in the market for maximizing their profit, and the independent system operator (ISO) clears the market based on social welfare maximization. System network constraints incorporating post-contingency control actions are described in the second stage of the market auction procedure. The market solutions, along with the BD, yield nodal spot prices (NSPs) and nodal congestion prices (NCPs) as byproducts of the proposed two-stage market auction model. Two benchmark systems are used to test and demonstrate the effectiveness of the proposed model.

• Transactions of Materials Processing
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• v.31 no.2
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• pp.57-63
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• 2022

The current study performed formability analysis of a heat exchanger separator for an electric vehicle to apply a high-strength aluminum sheet based on parametric analysis. Mechanical properties for sheet metal forming simulation were evaluated by tensile test, bulge test, and Nakajima test. Two-stage crash forming was established by considering the mass production process using conventional low-strength aluminum sheets. In this study, FEM for the two-stage forming process was conducted to optimize the corner radius and height for improving the formability. In addition, the possibility of a one-stage forming process application was confirmed through FEM. The prototype of the sample was manufactured as FEM results to validate the parametric analysis. Finally, this result can provide a one-stage forming process design method using the high-strength aluminum sheet for weight reduction of a heat exchanger separator for an electric vehicle.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.203-208
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• 2001

In this paper, the pumping performance of the three-stage disk-type drag pump which works in the outlet pressure range from 4 to 0.01 Torr is studied experimentally. The rotational speed of the pump is 24,000rpm, and nitrogen is used as a test gas, The pumping characteristics of various drag pumps are investigated. The inlet pressures are measured for various outlet pressures of the test pump. The maximum compression ratios for zero throughput are measured for three-stage, two-stage BSC type, helical-type, one-stage BSC type and one-stage OSC type, respectively.