• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.8
• /
• pp.88-93
• /
• 2020

The goal of this study is to determine the influence of major factors on the spiral surface microparticle injection machining of cylindrical specimens by the statistical method ANOVA. Before the experiment, rod-shaped test specimens and jigs for helical surface spraying were prepared, and the surface roughness was measured with a surface roughness meter. The injection particle, nozzle diameter, and injection pressure were the primary parameters of the experiment. Other factors that were considered were injection height, injection time, revolutions, and feed distance. The surface roughness after machining was measured, and the effects of the surface roughness data on the primary factors were determined with ANOVA.

• Journal of Welding and Joining
• /
• v.32 no.1
• /
• pp.28-33
• /
• 2014

In this paper, I-butt welding with 6mm thickness using Plasma-GMA welding was carried out. And weld characteristics of the Al-5083 aluminium alloy for Plasma-GMA hybrid welding was evaluated. The orthogonal experimental design was used to investigate the influence of plasma-MIG welding parameters such as plasma current, wire feeding rate, MIG-welding voltage and welding speed on the weld bead geometry and tensile strength using the ANOVA(Analysis of Variation). Then we conducted evaluation of contribution for process parameters. ANOVA results show that bead dimensions are affected by wire feeding speed, welding voltage and welding speed and tensile strength is mainly affected by welding speed and plasma arc current. Tensile strength was decreased by rise in plasma welding current because GMA welding current was decreased by plasma arc.

• Culinary science and hospitality research
• /
• v.14 no.1
• /
• pp.21-38
• /
• 2008

This research aimed to analyze the differences in financial variables classifying chain restaurants. A total of 126 samples were drawn from financial statements for $2001{\sim}2006$. As a result of analysis, there was a significant difference in Pillai's Trace, Wilks' Lambda, Hotelling's Trace, and Roy's Largest Root values at the significant probability value(p<0.05) based on F value in terms of stability among chain restaurants. Difference was found only in current rate and liabilities in ANOVA. There was a great difference in current rate among institutional restaurants, fast food restaurants, and cafeterias. There was a significant difference in Pillai's Trace, Wilks' Lambda, Hotelling's Trace, and Roy's Largest Root values at the significant probability value(p<0.05) based on F value in terms of restaurants' profitability. In ANOVA, difference was found only in net profits to net sales. It was revealed that all factors showed no significant differences in multiple comparison. All multi-variant test statistics showed a significant difference in growth and turnover. ANOVA showed a significant difference in net sales growth rate, net profit growth rate, and total assets growth rate.

• The Journal of Korean Academy of Prosthodontics
• /
• v.58 no.4
• /
• pp.282-289
• /
• 2020

Purpose: The aim of this in vitro study was to evaluate the accuracy of three different intraoral scanners (IOSs) on digital impressions of different types of endocrown cavity preparations. Materials and methods: Two human mandibular molar teeth were prepared with different endocrown abutment designs: one with a buccal wall (Class 2) and the other without a buccal wall (Class 3). Both cavity designs were scanned using a reference desktop scanner (E3) and three different intraoral scanners: Trios3 (TRI group), Cerec Omnicam (CER group), and i500 (I5 group). The obtained Standard Tessellation Language (.stl) datasets were exported to metrology software. The precision was evaluated based on deviations among repeated scan models recorded by each IOS. The trueness was evaluated based on deviations between the reference data and repeated scans. For detecting interaction, data were statistically analyzed using a univariate analysis of variance (ANOVA) and for analyzing the comparison of the test groups data were analyzed by one-way ANOVA and post-hoc Tukey test at the significance level of .05. Results: The deviation values for both cavity designs in the I5 group were significantly lower than those in the other IOS groups in terms of trueness. For both cavity designs, the TRI group exhibited better precision than the other IOS groups. Conclusion: Different technologies of IOS device's and different endocrown prepration designs affected the accuracy of the digital scans.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.1
• /
• pp.372-378
• /
• 2021

A body armor vest is a form of munition related directly to the safety and life of combatants. Therefore, it must meet the requirements for ballistic resistance. The ROK demands the performance of body armor vest meet the Level IIIA specified by the NIJ STD-0101.06 published by the US National Institute of Justice. This study performed acceptance tests on body armor vests. The factors for evaluating the ballistic resistance evaluated were not only whether it penetrates when shooting but also whether the BFS (Backface Signature) depth does not exceed 44 mm when it does not penetrate. The factors were assessed to determine if they were consistent or not. The BFS depth is affected by various test factors, such as the physical properties of the backing material and the changes in the amount of impact with the bullet velocity. In this study, an analysis of the bulletproof performance was performed by extracting the data with the same conditions using ANOVA to remove the influence of these external factors. The analysis revealed a correlation between the BFS depth, bullet velocity, vest conditions, and protection area. The mass production process was analyzed by estimating the Interval of BFS on each lot. Through this, a new methodology for ballistic resistance evaluation and paradigm for future quality assurance is suggested.

• Journal of Korea Port Economic Association
• /
• v.38 no.4
• /
• pp.199-214
• /
• 2022

A relative important analysis was conducted to determine what factors are required for port selection in Mokpo New Port and what needs to be addressed first in order to expand automobile and steel cargo handling. The port selection factors of Mokpo New Port were classified into 4 major and 13 intermediate categories, and AHP analysis was used. As a result, items such as 'port facilities', 'accessibility to international ports', 'port facility usage fees', and 'connectivity with neighboring cities/ports' were evaluated as important. The respondent groups were divided into shipowner and shipper, port operator and stevedore, and public official, and an analysis of variance (ANOVA) was conducted to verify if there was a difference in perception between the groups. As a result, shipowner and shipper, port operator and stevedore were similar, but there was a difference from public official group. Shipowner and shipper, port operator and stevedore with similar response characteristics were classified into the 'port practitioner' group, and public official were classified into the 'port policy maker' group, and the difference in perception between the group was tested. Therefore, there were differences in some major category items, and even in the intermediate category items such as 'possession of adjacent hinterland industrial complex', 'cargo equipment', '24-hour port operation', 'inland transportation cost', 'accessibility to international ports', 'marketing and incentives' with statistical. In other words, the 'port practitioner' group evaluated items that can increase cargo creation and handling productivity as important whereas the 'port policy maker' group considers port development and policies such as port infrastructure, connectivity with other ports, and incentive support items are more important.

• The Journal of the Korea Contents Association
• /
• v.13 no.12
• /
• pp.463-469
• /
• 2013

In this study, I examine whether differences in the levels of stress exist with regard to the police department size. To accomplish this, a way ANOVA analysis of variance(One-way ANOVA) was conducted. As a result, a significant difference was found in Job stress and traumatic stress according to the department size and grade. Specifically, first, in the job stress level on the department size, the smaller department size was, the higher job stress level was and the bigger department size was, the lower job stress level was. Second, in the traumatic stress level on the department size, the smaller department size was, the higher traumatic stress level was and the bigger department size was, the lower traumatic stress level was. Third, in the job stress level on the department grade, the lower department grade was, the lower job stress level was and the higher department grade was, the higher job stress level was. Fourth, in the traumatic stress level on the department grade, the lower department grade was, the lower traumatic stress level was and the higher department grade was, the higher traumatic stress level was.

• The Journal of the Korea Contents Association
• /
• v.12 no.9
• /
• pp.211-216
• /
• 2012

In this study, the relationship between the organizational characteristics of police officers and the level of post-traumatic stress disorder in the comparative analysis was to check for post-traumatic stress disorder, according to the organizational characteristics affect. To accomplish this, a way ANOVA analysis of variance(One-way ANOVA) was conducted. The department in post-traumatic stress disorder level, a significant difference was found. It was more likely to be exposed to a traumatic experience if who is working in the front-line department. Post-traumatic stress disorder according to the work unit, a significant difference was found. The level of Post-traumatic stress disorder in outside job unit officers was higher than that of desk job unit offcers. Post-traumatic stress disorder according to the rank and duration of employment and the administrative district level, a significant difference was not found.

• Journal of Korean Society of Forest Science
• /
• v.97 no.6
• /
• pp.565-569
• /
• 2008

Geographic variation of characteristics of cone, seed and bract morphology were examined in 8 populations of rare endemic Abies nephrolepis (Trautv.) Maxim and A. koreana Wilson. Additionally we studied classification index to distinguish between the species by the method of discriminant analysis. Nested ANOVA showed that there were statistically significant differences among populations as well as among individuals within populations in all 13 morphological traits. In the seed length, seed index, bract width, and bract index of A. nephrolepis and the bract width and index of A. koreana, variance components among populations were larger than those among individuals within populations. In discriminant analysis, three traits (cone width, length of seed wing, and bract length) were found to be useful in discriminating A. nephrolepis from A. koreana. The optimal classification results of stepwise selection were discriminated length of seed wing and bract length.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.12
• /
• pp.339-345
• /
• 2020

In the field of defense, one-shot devices such as missiles are stored for a long period of time after they are manufactured, so it is essential to predict their storage life. A study was conducted to find the shelf life of a Li-ion battery used in one-shot devices. To do this, a Li-ion battery that has been used in weapon systems for more than 5 years was secured. A non-functional test was performed on the battery to check for external changes or failures. After the non-functional test, a discharge test was performed to measure the performance after storing it. Through the test, the performance was checked, including the initial charging voltage, discharge time, and battery temperature, and the trend of the change was identified. An F-test, One-way ANOVA, and regression analysis were performed to verify the aging, and the shelf life of the battery was estimated by an approximation formula that was derived through a regression analysis. As a result of the ANOVA, the p-value was less than the reference value of 0.05, and the performance of the battery decreased by more than 15% after a certain period of time. This change is assumed to result from the change in physical properties of the lithium polymer cell.