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Additive manufacturing (AM) technology is increasingly being used in the aerospace industry due to its advantages for aerospace components such as reduction of weight. A deep understanding of the behavior and properties of additively manufactured materials or parts is required to effectively carry out the certification process which is inevitable for aerospace components. However, since AM has so many parameters that affect the performance of products, the help of high-fidelity process simulation techniques is essential to fully analyze and understand their effects. In this research, we propose a new method to effectively implement the thermal analysis for process simulations of laser powder-bed fusion technique, a representative AM technique for metal materials, using existing commercial finite element analysis software. Thermal analysis for simulations of AM process is performed and the melt pool size is compared with test results to verify the accuracy of the simulation. In AM process simulations, material properties may vary significantly with temperature, and they are also dependent on the temperature history of the material because whether the current state is a powder or solid state is determined by the maximum temperature value in the past temperature history. Therefore, in this paper, user-defined subroutines and field variables are implemented so that the temperature history of each integration point for the finite element analysis can be properly tracked and appropriate material properties can be assigned accordingly. Using the proposed methods, thermal analysis for AM process simulations can be performed successfully with good accuracy compared with the existing test results.

In this study, we analyzed the factors affecting the introduction of Smart Factory by domestic SMEs through AHP analysis and tried to provide...

Consideration of Discontinuance of Malaria Antibody Test for Blood Donor Screening Jae-Won Kang, Kyoung Won Youn, Kwang Huh, Chae Seung Lim, Byung-Chul Chun, Joon Sup Yeom, Deok-Ja Oh Blood Transfusion Research Institute, Korean Red Cross, Blood Service Headquarter, Korean Red Cross, Wonju, Department of Laboratory Medicine, Korea University Guro Hospital, Department of Preventive Medicine, Korea University College of Medicine, Department of Infectious Diseases, Kangbuk Samsung Hospital, Seoul, Korea

Recently, the use of small-sized BaTiO3 particles for ultra-thin MLCC research has increased as a method for minimizing the dielectric layer’s thickness in thick film process. However, when particles smaller than 100 nm are used, the reduced particle size leads to a reduced dielectric constant. The use of nanoparticles, therefore, requires an increase in the amount of additive used due to the increase in the specific surface area, thus increasing the production cost. In this study, a novel method of coating 150-nm and 80-nm BaTiO3 powders with additives and mixing them together was employed, taking advantage of the effect obtained through the use of BaTiO3 particles smaller than 100 nm, to conveniently obtain the desired dielectric constant and thermal characteristics. Also, the microstructure and the dielectric properties were evaluated. The additives Dy, Mn, Mg, Si, and Cr were coated on a 150-nm powder, and the additives Dy, Mn, Mg, and Si were coated on 80-nm powder, followed by mixing at a ratio of 1:1. As a result, the microstructure revealed grain formation according to the liquid-phase additive Si; additionally, densification was well realized. However, non-reducibility was not obtained, and the material became a semiconductor. When the amount of added Mn in the 150-nm powder was increased to 0.2 and 0.3 mol%, insignificant changes in the microstructure were observed, and the bulk density after mixing was found to have increased drastically in comparison to that before mixing. Also, non-reducibility was obtained for certain conditions. The dielectric property was found to be consistent with the densification and the grain size. The mixed composition #1-0.3 had a dielectric constant over 2000, and the result somewhat satisfied the dielectric constant temperature dependency for X6S.

본 연구는 ``살아있는 교과서``라고 불리는 영자신문을 활용한 영어교육인 English Newspaper In Education(ENIE)이 고등학교 학생들의 영어 이해력과 학습태도에 미치는 영향을 알아보는데 목적이 있다. 영어 독해-듣기 학습에서 영자신문을 활용하면 학생들의 흥미를 자극하고 학습 동기를 부여하여 학습 의욕을 높여준다. 또한 신문은 영어 사용 국가의 문화에 대한 다양한 주제와 정보를 제공하는 등 좋은 학습 자료가 된다. 실험은 30차시 15주간의 영자신문 강의로 시행되었으며, 사전 사후 테스트 결과를 비교하여 영어이해력 향상과 학습태도의 변화를 측정하였다. 실험의 결과는 읽기-듣기 활동에서 영자신문의 사용은 일반적인 교과서, 문제집, 방송교재를 활용한 학습에 비해 많은 장점이 있고, 학습자들의 흥미와 관심을 고취시킬 수 있다는 사실을 발견하였다. 실험 전후의 설문조사 및 사전, 중간, 사후 테스트 결과 모두 영자신문의 교육적 장점을 뒷받침하는 결과를 내었으며 대다수의 학생들은 실험 이후에도 영자신문의 사용에 대한 관심과 희망을 보여주었다. 앞으로 영자신문 활용 수업의 효과를 높이기 위하여 교사들의 적극적인 참여와 각종 교수 모델과 보조 학습 자료의 개발 및 배포가 필요하다.

Background and Objectives The Korean Red Cross began nucleic acid amplification testing (NAT) for HIV and HCV in February 2005, and added HBV NAT beginning in June 2012. The current NAT system utilizes a multiplex assay for simultaneous detection of HBV DNA, HCV RNA and HIV-1 RNA. For samples that are reactive in the multiplex assay, we do specific tests for each virus. However, there have been cases of non-discriminated reactive (NDR) results which appear to be the result of non-specific reactions or cross-contamination, although some cases are considered to arise from the presence of low levels of HBV DNA due to occult hepatitis B infection. Materials and Methods We examined the incidence of NDR results in previous donations of some NAT-reactive donors. Additionally, for those donors with NDR results, we performed an HBV core antibody (anti-HBc) assay. Results From November 2015 to March 2016, there were 408 NAT-reactive donors. Of these, nineteen HBV NAT-reactive donors showed a history of NDR results in the past donations. Seven donors showed NDR results more than once. Of 771 NDR donors, 362 (47·0%) were anti-HBc reactive. Conclusion The NDR donors had a substantially higher rate of anti-HBc reactivity than other blood donors indicating that some with anti-HBc reactivity represent donors with occult HBV. Therefore, the incorporation of an anti-HBc testing for NDR donors could improve blood safety testing for the Korean Red Cross.

This study examines direct and mediating links between perceived discrimination and the acculturation process to the mainstream culture among collage-age Koreans in Australia: the mediating variable (peer social support of mainstream group members) by which a predictor (perceived discrimination) influences an outcome variable (the acculturation process to the mainstream culture). The data were collected from college-age Koreans in Australia using the East Asian Acculturation Measure, the Perceived Discrimination Scale and the Social Support Appraisal Scale. This study found that the benefits of social support made more positive attitude toward the mainstream cultural in Australia. That is, an increase in perceived discrimination was significantly associated with the negative experience of acculturation process from one`s adaptation to the new culture, and this relationship was attenuated by higher levels of social support. These findings not only contribute to cross-cultural education and practice, but also increase cultural sensitivity and awareness in working with students of non-English-speaking background.

This paper intends to explore the social and cultural implications of convergence media, based on Goffman's situational approach. The situational segregation of regions makes us to re-interpret the current private and public spheres and helps us to reveal the principle and structure hidden in the new middle region. An environment of convergence media is nullifying the separation of private and public spheres, while letting a new middle region appear.

Modern freight transport pursues not only the reduction of logistic costs but also aims at green logistics and efficient shipments. In order to accomplish these goals, various policies regarding the multimodal shipment and stopover to logistic facilities have widely been made. Such situation requires changes in existing methods for analyzing freight demand. However, the reality is that a reliable freight demand forecast is limited, since in the transport research field there is no robust freight demand model that can accommodate transshipments at logistic facilities. This study suggested a novel method to analyze freight demand, which can consider transshipments in multi-modal networks. Also, the applicability of this method was discussed through an example test.

In this paper, optimal pilot sequence designs for MIMO-OFDM systems in multi-cell environments are provided. The proposed multi-cell optimality criterion is to minimize the worst-case MSE of an LS-based channel estimator. To satisfy the multi-cell optimality, it is found that the pilot sequence set, having the perfect auto-correlation property, should meet the Welch bound and the maximum magnitude of the cross-correlation function should be further minimized. Multi-cell optimal pilot sequence designs for various pilot types and their DFT representations are proposed by adopting Chu sequences and a tight upper-bound on the maximum size of the pilot sequence set is derived for a given pilot sequence length and the maximum allowed cross-correlation value. Simulation results show that the proposed pilot sequences can improve both the MSE performance and the system performance in multi-cell environments.