• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2001년도 추계학술발표대회 논문집
• /
• pp.29-32
• /
• 2001

The objective of this work was to optimize processing parameters of hybrid thermoplastic composites in compression molding. The mechanical properties of the composites manufactured with various forming conditions were measured to characterize processing parameters. Polypropylene(PP) composites containing randomly oriented long carbon fiber and carbon black were used in this work. The composite materials contained 5%, 10%, 15%, and 20% carbon fiber and 5%, 10%, 15%, 20%, and 25% carbon black by weight. Compression molding was conducted at various mold temperatures. The temperature of the material in the mid-plain was monitored during the forming. Crystallinity was also measured by using XRD. The tensile modulus of the composites increase, with increasing the mold temperature. However, the impact strength of the composites decreases as mold temperature increases.

• 한국세라믹학회지
• /
• 제46권4호
• /
• pp.345-349
• /
• 2009

In Part II, the paper will describe a three-phase alumina-based nanoceramic composite demonstrating superplasticity at a surprisingly lower temperature and higher strain rate. One important factor in the processing of these nanocomposites was the use of the electrical field assisted sintering method, SPS. These improvements in mechanical properties were briefly discussed in the context of the results from the microstructural investigations. SPS forming approach provides a new route for low temperature and high-strain-rate superplasticity for nanostructured materials and should impact and interest a broad range of scientists in materials research and superplastic forming technology.

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
• /
• pp.236-237
• /
• 2006

Cold spraying is a fairly new coating technique, which within the last decade attracted serious attention of research groups and spray companies. As compared to thermal spraying, the low process temperatures in cold spraying result in unique coating properties, which promise new applications. Since particles impact with high kinetic energy in the solid state, new concepts to describe coating formation are requested to enable the full potential of this new technology. The present contribution gives a brief review of current models concerning bonding, supplying a description of the most influential spray parameters and consequences for new developments. With respect to spray forming by cold cold spraying, microstructures and thick, further machineable structures are presented.

• 한국환경과학회지
• /
• 제28권2호
• /
• pp.211-217
• /
• 2019

A Numerical modeling approach is usually applied to reproduce the physical phenomena of a fill dam-break. The accuracy of the dam-break model depends on the physical structure that defines input variables such as the storage volume, breach formation and progress, and the parameters of the model, which are subjective as they are prescribed by users. In this study, a sensitivity analysis was performed for the nonlinear breach progression curve that was already developed, which includes four parameters. The study focuses on the two of the parameters which control the breach forming time and peak discharge. The model is coupled with a two-dimensional flood simulation model (FLO-2D) to examine flood coverage and depth. It is generally observed that the parameter ${\beta}$ controls only the breach forming time, the parameter ${\gamma}$ is particularly sensitive to the peak flow.

• International Journal of Computer Science & Network Security
• /
• 제22권2호
• /
• pp.348-356
• /
• 2022

The article is devoted to substantiation of theoretical and methodical bases of formation of the organizational-economic mechanism of maintenance of stability of development of region on the bases of influence of potential-forming space in the conditions of formation of creative economy. It was found that the organizational-economic mechanism due to its multifaceted nature does not have a single generally accepted definition, and its acceptable scale and complexity is reflected in the structure, which is very dependent on the scope and conditions of its application, can be very different and contain different elements. In view of this, in order to highlight the characteristics that are inherent in the organizational-economic mechanism of sustainable development of the region on the basis of potential-forming space in the formation of creative economy, the article examines the properties and characteristics of direct organizational and economic mechanism. The necessity of basing the process of formation of any organizational-economic mechanism, including the organizational-economic mechanism of ensuring the sustainability of the region on the basis of the potential-forming space in the conditions of creative economy on the system of principles. In this context, the author's vision is proposed and a set of principles for the formation of organizational-economic mechanism for sustainable development of the region on the basis of the potential of the potential-forming space in the creative economy, as well as revealed the essence of each. According to the structural aspect, the organizational-economic mechanism of ensuring the sustainability of the region's development on the basis of the potential-forming space is proposed to be presented as a set of seven stages, which are implemented in a certain sequence. Within the limits of this research the sequence of realization of the stages making process of formation of the organizational-economic mechanism of maintenance of stability of development of region on the basis of influence of potential-forming space in the conditions of formation of creative economy is defined and their maintenance and essence is presented.

• The Journal of Asian Finance, Economics and Business
• /
• 제7권6호
• /
• pp.61-71
• /
• 2020

The study examines the impact of corporate governance mechanisms, such as board characteristics on corporate social responsibility disclosure (CSRD). The data on CSRD items and board characteristics have been collected by content analysis of the annual reports of 30 publicly-listed banks in Bangladesh covering six years, from 2013 to 2018. More specifically, the directors' report, the chairman's statement, notes to the financial statement and CSR disclosure reports included in annual reports were used to collect the CSRD data. The empirical analysis applies the ordinary least square and the generalized method of moments. The results of the study have revealed that board size, board independence, female board member, and foreign directors have a significant positive impact on CSRD. By contrast, political directors and audit committee size have a negative impact on CSRD. Interestingly, accounting experts on boards ensure more CSRD as they curb the influence of politicians on the board. Thus, it is better to increase accounting experts and decrease politicians on the board. These findings provide valuable insights into the process of forming a suitable CSR policy by connecting the efforts of the board, government, and regulatory bodies to enhance the performance of banks to CSR as well as to CSRD.

• 한국태양에너지학회 논문집
• /
• 제40권4호
• /
• pp.23-33
• /
• 2020

The loss in photovoltaic power due to hailstorms has been highlighted as a major issue in the sustained growth of the PV power plant industry. This study investigates the safety of a solar module by conducting a numerical analysis of a hail test according to the IEC 61215 standard. Our study aims to elucidate the detailed behavior between the ice and solar modules and the micro-cracks forming on solar modules during hailstorms. To analyze the impact of hail, we used the ANSYS AUTODYN software to evaluate the impact characteristics on a solar module with different front glass thicknesses. The simulations show that a solar module with a glass thickness of 4.0 mm results in excellent durability against hail. The results indicate the feasibility of using simulations to analyze and predict micro-cracks on solar modules tailored to various conditions, which can be used to develop new solar modules.

• 산경연구논집
• /
• 제10권10호
• /
• pp.23-34
• /
• 2019

Purpose - Most past studies related to this focused on the physical attractiveness of service employees, but this study emphasizes the social attractiveness and not just the physical attractiveness of employees. Therefore, the purpose of this study is to first categorize attractiveness as physical attractiveness and social attractiveness and to examine the impact of physical attractiveness on social attractiveness for service industry employees. Secondly, this study aimed at verifying the impact of physical attractiveness and social attractiveness on interpersonal trust. Third, it aimed at revealing the impact of interpersonal trust on customer satisfaction, as well as satisfaction on loyalty. Research design, data, and methodology - Questionnaires were distributed to customers that used beauty salon services, among the various service industries, to verify the hypothesis of this study. Also, hypothesis was analyzed with the structural equation method using Amos 20.0. Results - When presenting the results on verifying the research hypothesis, it was found that physical attractiveness had a positive impact on social attractiveness. Second, while physical attractiveness did not have a positive impact on interpersonal trust, social attractiveness was found to have a positive impact on interpersonal trust. Such results show that in forming interpersonal trust, social attractiveness was more important than physical attractiveness for service industry employees. This result is in contrast with the results of past studies, but it is different in that previous studies suggested only physical attractiveness and did not present social attractiveness in the hypothesis. Third, it was found that interpersonal trust had a positive impact on satisfaction, while satisfaction did not have a positive impact on loyalty. Conclusions - The biggest implication of this study is that it presented social attractiveness, which was rarely dealt with in past studies. Also, this study is significant in that it examined the relationship of physical attractiveness and social attractiveness. The results of this study show that in the service industry, the role of human elements such as service employees is important and that in addition to physical attractiveness, social attractiveness in the course of interaction such as communication with customers can also be an important strategic element.

• Steel and Composite Structures
• /
• 제38권2호
• /
• pp.151-164
• /
• 2021

During the pipe forming process, a steel plate undergoes inelastic behavior multiple times under a load condition repeating tension and compression in the circumferential direction. It derives local reduction or increase of yield strength within the thickness of steel pipes by the plastic hardening and Bauschinger effect. In this study, a combined hardening model is proposed to effectively predict variations of yield strength in the circumferential direction of API-X65 and X70 steel pipes with relatively low t/D ratio during the forming process, which is expected to experience accumulated plastic strain of 2~3%, the typical Lüder band range in a low-carbon steel. Cyclic tensile tests of API-X65 and X70 steels were performed, and the parameters of the proposed model for the steels were calibrated using the test results. Bending-flattening tests to simulate repeated tension and compression during pipe forming were followed for API-X65 and X70 steels, and the results were compared with those by the proposed model and Zou et al. (2016), in order to verify the process of material model calibration based on tension-compression cyclic test, and the accuracy of the proposed model. Finally, parametric analysis for the yield strength of the steel plate in the circumferential direction of UOE pipe was conducted to investigate the effects of t/D and expansion ratios after O-forming on the yield strength. The results confirmed that the model by Zou et al. (2016) underestimated the yield strength of steel pipe with relatively low t/D ratio, and the parametric analysis showed that the t/D and expansion ratio have a significant impact on the strength of steel pipe.

• Composites Research
• /
• 제34권2호
• /
• pp.115-122
• /
• 2021

복합재료 중에서 SMC(sheet molding compound) 복합재료는 자동차의 차체 성형에 주로 쓰이고 있다. 자동차 산업에서는 차량 사고를 고려하여야 하므로 재료의 충돌 거동 및 특성에 관한 연구는 필수적이다. 충돌은 짧은 시간에 일어나기 때문에 육안으로 확인이 어렵다. 따라서 충돌 거동을 확인하기 위해서는 유한요소 모델을 이용한 충돌 손상 해석이 필요하다. 충돌 손상 해석을 위해서는 SMC 복합재료의 손상 모델에 대한 파라메터가 요구된다. 본 연구에서는 SMC 복합재료의 손상 모델에 대한 파라메터를 획득하기 위해 인공신경망 기법을 적용하였다. LS-DYNA에서 파라메터에 따른 결과를 이용하여 대체 모델을 구성하였다. 자유 낙하 충돌 실험에서 얻은 흡수 에너지와 인공신경망 모델을 이용한 흡수 에너지를 비교하여 최적화된 파라메터를 획득하였다. 획득한 파라메터를 유한요소 모델에 적용해 결과를 비교하여 파라메터의 신뢰성을 검증하였다.