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고강도 구리 라이너가 적용된 종횡비 2.73 성형작약탄의 제트형성 및 표적관통 특성에 대한 수치해석 연구
김동후,신현호,정동월,이은호,서승재,윤태식 한국CDE학회 2019 한국CDE학회 논문집 Vol.24 No.1
The jet formed from the shaped charge with an aspect ratio of 2.73 and a higher strength liner than the conventional liner is shown to form a region where the temperature is higher than the melting point of copper, based on the result of the numerical analyses using an elastic-perfectly plastic constitutive model for the copper liner. This phenomenon is ascribed to the increased plastic work of the high-strength liner. From the result of numerical analyses using an appropriate strain-, strain rate-, and temperature-dependent constitutive model that can describe the stress upturn phenomenon of copper, the flow stress control of the high-strength copper liner is shown to be able to form an appropriate amount of melted volume, which increases the effective jet volume with a velocity higher than 2 km/s, fosters jet extension without breakage, and eventually increases depth of penetration in the target. Necessity of experimental verification for these findings is addressed together with a future activity to obtain the strain rate- and temperaturedependent fracture equivalent strain of the high-strength copper liner.
김동후,Joseph Michael Czabovsky,Michele Lynn Meyer 한국광고학회 2022 광고학연구 Vol.33 No.4
This study investigates how using a specific SNS platform has impact on users’ self-construals. Also, this research examines the effect of the association between SNS platforms and users’ self-construals in improving the efficacy of advertising in SNSs. Based on self-construal theory and information processing model (affective vs. cognitive processing), it is assumed that users’ self-construals can be primed by their SNS use and the primed self-construals can have impact on their information processing in SNS contexts. Two laboratory experiments were conducted to test these assumptions. A total of 191 (Study 1 – 74 & Study 2 – 117) undergraduate students participated in this research. The findings from study 1 empirically supported that SNS platforms could prime users’ self-construals differently. The results from Study 2 not only provided compatible evidence that SNS platforms can change users’ self-construal but also demonstrated the interplay between the primed self-construal by SNS platforms and ad types (emotional appeal vs. cognitive appeal ad) in shaping individuals’ response toward the ad. Also, the mediating role of users’ self-construal on the interplay between SNS platforms and ad types.was confirmed. Since the current research tested two image-based SNS platforms with undergraduate students, future research may need to test different population with more various platforms to re-examine the findings from this study. The current research contributes to the field by expanding the self-construal concept in SNS research, as well as provides practical implications to improve the efficacy of SNS advertising campaigns.
김동후,한진수,우인봉,정준재,박시우,허경철,하주형,윤찬석 한국포장학회 2017 한국포장학회지 Vol.23 No.3
The purpose of this study was to investigate the quality change of fresh-cut tumeric (Curcuma Longa Linne) according to packaging method during storage time. The fresh-cut tumeric were packaged in three different methods : degassing valve packaging (DVP), CO2 gas absorber packaging (CAP) and micro-perforated packaging (MPP). After the samples were packaged, they were stored for 15 days at 4 and 23oC respectively. The following parameters were observed to indicate the quality changes of the samples: weight loss, CIE L*a*b* colour difference, variation of gas composition inside the package, curcumin contents and changes in hardness of fresh-cut tumeric. DVP did not effectively release CO2 gas to the outside. MPP was suitable to release CO2 gas. However, MPP showed very fast browning and erosion, because a large amount of oxygen was introduced through the perforated hole on the film. CAP was most effective packaging method to inhibit browning, to prevent expansion of the packaging by CO2 gas and to minimize weight loss of freshcut tumeric.
김동후,이소영,성윤희 한국정보사회학회 2020 정보사회와 미디어 Vol.21 No.1
This study builds upon existing research examining the relationship between social networking sites (SNS) use and social capital by investigating what drives the underlying reciprocal interaction. While prior investigations of the SNS-social capital relationship employed self-report methods, this study employs a laboratory-based experiment. As strong exemplars of SNS, Snapchat and Instagram, specifically, were chosen for investigative focus. A total of 161 undergraduate students from a major southeastern university in the U.S. participated in this research in exchange for extra credits. Participants were provided questions about their usage patterns, such as time spent on SNS usage in general and intensity of the assigned SNS use (Snapchat or Instagram). Then, participants were asked to log into their Snapchat or Instagram accounts and spend twenty minutes using it as they normally would, such as posting snaps and liking and browsing pictures of others. Based on the average time spent per day on Instagram and Snapchat by U.S. users, the twenty-minute experimental condition was designed. After twenty minutes, their social capital was measured Results demonstrated that participants who used Snapchat were more highly associated with bonding social capital (strongly tied relationship) than those who used Instagram. However, using Instagram did not lead participants to be more concerned with bridging social capital (weakly tied relationship) than those using Snapchat. In addition, when an individual’s social capital was examined as it existed both prior to and after using SNSs, only bonding social capital in the Snapchat condition was significantly changed. After using Snapchat, individuals’ bonding social capital became stronger than it was pre-SNS engagement. However, when individuals used Instagram, no significant difference in bridging social capital was detected. Through the laboratory experiment, the current research can provide more valid and accurate data for understanding the relations between SNS use and users’ social capital. Since it is challenging for individuals to remember or precisely describe their SNS use, several researchers have expressed the need to adopt more ideal methods to directly measure data, such as a laboratory-based study. By avoiding the validation issues that exist with self-report measures, the current research contributes to the improvement in methodological approaches to SNS research. In addition, the study found that bonding social capital can be influenced by a certain type of SNS platform (e.g., Snapchat), whereas bridging social capital was not. Hence, individuals can obtain their bridging social capital without limitation with regard to SNS type, but to obtain bonding social capital, a SNS platform that allows one to interact and develop strong social ties can be more effective than other SNS platforms. At the same time, given that social capital allows a person to make use of resources from other members in one’s networks, it can be expected that using Snapchat, which can remind users of their bonding social capital, may be more effective for brands to construct strong ties with their consumers. Therefore, the results of this research can be beneficial for brand managers creating SNS marketing plans.