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Through an investigation of the microstructure and mechanical properties of extruded Mg–5Bi–xSn (BT5x, x = 0, 2, 4, and 6 wt%) alloys, this study demonstrates that the addition of Sn to an Mg–5Bi binary alloy significantly improves the tensile strength of the extruded alloy. All the extruded alloys exhibit a typical basal fiber texture and a partially dynamically recrystallized (DRXed) microstructure consisting of fine DRXed grains and coarse unDRXed grains. As the Sn content increases from 0 wt% to 6 wt%, the average size of the DRXed grains decreases from 4.2 to 2.8 μm owing to the increase in the amount of precipitates via their grain-boundary pinning effect. The extruded B5 and BT52 alloys contain numerous Mg3Bi2 precipitates, but their size and number density are smaller and higher, respectively, in the latter alloy. Numerous Mg2Sn precipitates as well as Mg3Bi2 precipitates are present in the extruded BT54 and BT56 alloys, and the number density of the Mg2Sn precipitates is higher in the latter alloy because of its higher Sn content. The addition of 2 wt% Sn to the B5 alloy significantly improves the yield strength (YS) and ultimate tensile strength (UTS) of the extruded alloy—by 76 and 57 MPa, respectively. This drastic improvement is the combined outcome of enhanced grain-boundary hardening, precipitation hardening, and solid-solution hardening effects induced by the refined DRXed grains, numerous precipitates, and Sn solute atoms, respectively. The further addition of 2 wt% or 4 wt% Sn to the BT52 alloy leads to moderate increments in the YS and UTS of the extruded alloy. Specifically, each addition of 2 wt% Sn increases the YS and UTS by ~26 and ~20 MPa, respectively, which is attributed mainly to the additional precipitation hardening effect induced by the Mg2Sn precipitates.

The present work deals with the formation and stabilization of the 18R lamellar long-period stacking order phase (LPSO) through friction stir processing of a GWZ magnesium alloy. In this regard, the formation sequence was investigated in detail, where the metastable LPSO structures were formed in the matrix and then transformed into the 18R structure. The involved micro-mechanism is also discussed with emphasis on the formation of a GP-like zone using high-resolution transmission electron microscopy.

To investigate the surface electromyography (EMG) activity of the temporalis, masseter, digastric, and infrahyoid muscles during passive jaw opening in healthy adults.The EMG activity of the masseter, temporalis, digastric anterior belly, and infrahyoid muscles on the right side was recorded during the four jaw-opening tasks: active opening to 20 mm (AO20); active opening to 40 mm (AO40); passive opening to 40 mm with a rubber mouth prop on the right posterior teeth (POR40); and passive opening to 40 mm with a mouth prop on the left posterior teeth (POL40).The EMG amplitude of the digastric anterior belly and infrahyoid muscles in either POL40 or POR40 was significantly less than that in AO20 or AO40, respectively.Passive jaw opening reduces the EMG activity of the digastric and infrahyoid muscles significantly and could help reduce the load on these muscles during prolonged mouth-opening conditions.

An extruded Mg-8.2Gd-3.6Y–1.6Zn–0.5Zr alloy containing blocky long-period stacking-ordered (LPSO) phase was subjected to a set of single and multi-pass friction stir processing trials. The evolutions of the microstructure and the secondary phases were investigated in details, and the correlations between the microstructure, the macro-texture and the room-temperature mechanical properties were explained. An outstanding grain refinement was achieved after applying just one friction stir processing pass, while the coarse blocky long-period stacking ordered phase was significantly broken into the fine particles. The occurrence of particle-stimulated nucleation process was identified as the main recrystallization mechanism, and this in turn could lead to appreciable texture weakening. In addition, some of the secondary phases were dissolved in the matrix and successively transformed into cubic RE-rich particles dynamically. The capability of phase transformation and dynamic precipitation were intensified through higher passes and the volume fraction of dispersed RE-rich particles located at the grain boundaries was increased. An ultrafine and relatively homogenous microstructure was also developed at the highest level of imposed equivalent strain. In the current work, the room-temperature mechanical properties of the thermomechanically processed materials were also explored. In spite of previous reports on the severely deformed magnesium alloys, the strength and ductility were significantly improved after friction stir processing. These were explained considering the grain refinement, fragmentation, transformation, suitable distribution of the second phases, and texture weakening which was resulted from the activation of non-basal slip systems.

The purpose of this study was to investigate the awareness of the necessity and importance of liberal arts education and to examine the satisfaction of college students with their liberal arts courses. This study was conducted from June 1&ndash, 15, 2018, for college students who are taking liberal arts courses. The collected data were analyzed using the SPSS 24.0 and AMOS 24.0 statistical package programs. To understand the general characteristics of the survey subjects, a frequency analysis, exploratory factor analysis, correlation analysis, and reliability analysis were performed to measure the reliability and validity of the measurement tools, and a structural model analysis was conducted to verify the proposed research model. The result shows that a professor&rsquo, s professionalism has a positive influence on the perception of a subject&rsquo, s importance and necessity after the course, diversity has a positive influence on satisfaction in liberal arts education. Favorable changes in the perception of importance and necessity have a positive effect on satisfaction level. Our findings imply that colleges should operate an integrated student-selective education course that allows all students to select and take liberal arts courses. It should be organized to secure full-time professors who will be exclusively responsible for liberal arts curriculums.

The effect of aging on yielding, strain-hardening, and texture evolution of ZK60 alloys was investigated during uniaxial warm compression at various temperature and deformation rates. Solid-solution heat-treatments (T4) and aging (T6) affected the behaviors of flow curves. The aged samples had a higher level of yield stress and lower strain hardening rates than the solution heat-treated samples. Linear strain-hardening behavior was examined using a visco-plastic self-consistent (VPSC) model and electron backscatter diffraction (EBSD). Predictions of the flow curve, twinned volume fraction and texture evolution of ZK60 alloys were compared with experimental results. Linear strain-hardening of flow curves was related to the strong activation of tensile twinning, { 10 1 ¯ 2 } , along with slip systems. Most precipitates formed during aging consisted of Zn and Zr elements. The effect of the aging process on deformation modes and stacking faults was discussed based on transmission electron microscopy (TEM) and VPSC modeling.

This study evaluated the intraexaminer repeatability of measurements of surface electromyography (EMG) variables and functional indices of the myoelectric signals from the masseter and temporalis muscles bilaterally in 15 healthy men. The test was repeated on two different days without templates. The resting muscle activity was recorded once, and two kinds of maximum voluntary contraction (MVC) tasks were performed and recorded three times. The two MVC tasks involved clenching the teeth and biting down on two cotton rolls bilaterally with the posterior teeth. The intraclass correlation coefficient (ICC) of amplitude was >88% and that of frequency was >95% during the two MVC tasks but not under resting conditions. The ICC of the asymmetry and activity indices during the two MVC tasks was >76%. A Bland-Altman analysis revealed no significant difference in amplitude or frequency or in the two indices between the two days during the MVC tasks. In conclusion, the measurements of surface EMG variables and the indices obtained according to the study protocol were highly repeatable in healthy men. Additional studies using templates and intraexaminer measurement errors are warranted in both men and women for complete validation of these findings.

Strength drop after welding of Al-Mg-Si aluminum alloys has been a crucial issue in industrial applications. Friction stir welding combined with a cooling system was carried out, and microstructure and mechanical properties of the welded Al-Mg-Si alloys were examined. Welding with cooling increased yield strength and decreased elongation of Al-Mg-Si alloys. Tensile strength and overall grain size of the welded zone varied with welding speed. The width of the welded zone based on hardness distribution clearly depended on welding speed. Overall, hardness dropped with coolant.

The purpose of this article was to not only review historically the growth and development of dancesport, to but also seek to inform the value and prospect of dancesport in Korea. To achieve the purpose of the paper, the result of this article was framed into four time periods for a historical review of Korean dancesport growth and development: the late 1880s - the mid 1940s, the late 1940s - the late 1980s, 1990s and 2000s onwards. First, the first period was from the late 1880s to the mid 1940s when the nation accepted a social dance and western dance and tradition especially in upper-class Korean society. Second, the second period was from the late 1940s to the late 1980s when social dances (or ballroom dance) were suppressed under the military-based regime. The most likely explanation for this was a tradition that Korea society consider distinction between the sexes as a virtue. Third, third period was the 1990s when the social dance (ballroom dance) was developed officially into dancesport. Actually, the 1990s saw the sport built up a positive image while a negative image was portrayed by the military-based government. Fourth, the fourth period was the 2000s onwards when the sport has been developed as a sport and culture in a sound and systematic manner. Indeed, the sport has come to meet the public tastes.

This study examines the impact of franchisor social responsibility (FSR) and franchisor image on franchisees. Based on prior research, the study hypothesizes that FSR and franchisor image influence qualities of the relationship with the franchisees (e.g., franchisee trust, franchisee satisfaction). The model was tested on the data collected from food service franchisees in South Korea. The study finds that FSR and franchisor image are critical for building franchisees’ trust in the franchisor, which affects franchisees’ satisfaction and their long-term orientation. We offer several implications related to the findings.

The COVID-19 pandemic has created the opportunity to conduct a huge experiment with online classes in the university setting. The objectives of this study are (1) to provide obvious insight into determining factors driving greater intention of students to use online learning systems based on an integrated technology acceptance model (TAM) and theory of planned behavior (TPB), and (2) to provide the moderating role of innovativeness as a key factor. An online survey was conducted with 216 university students taking hospitality and tourism studies in Busan, Korea. The results of the study are as follows. First, perceived ease of use affects perceived usefulness, perceived usefulness affects attitude, whereas perceived ease of use does not directly affect attitude. Second, attitude and subjective norms positively influence behavioral intention, while perceived behavioral control does not. Third, user innovativeness plays a moderating role in the relationship between subjective norms and behavioral intention. As part of the lessons learned from COVID-19, it is meaningful to provide insightful implications to academia, specifically to the college of hospitality and tourism.

Texture and microstructure evolution of ingot and twin-roll casted Mg&ndash, Al&ndash, Mn magnesium sheets were examined during deep drawing at elevated temperatures. The twin-roll casted sheets possessed smaller grain sizes and weaker basal intensity levels than the ingot-casted sheets. The strength and elongation at room temperature for the twin-roll casted sheets were greater than those of the ingot-casted sheets. At elevated temperatures, the ingot-casted sheets showed better elongation than the twin-roll casted sheets. Different size and density of precipitates were examined using transmission electron microscopy (TEM) for both ingot-casted and twin-roll-casted sheets. The deep drawing process was also carried out at various working temperatures and deformation rates, 225&nbsp, &deg, C&nbsp, to&nbsp, 350&nbsp, C and 30 mm/min to 50 mm/min, respectively. The middle wall part of cups were mainly tensile deformation, and the lower bent regions of drawn cups were most thinned region. Overall, the ingot-casted sheets revealed better deep drawability than the twin-roll casted sheets. Microstructure and texture evolution of the top, middle and lower parts of drawn cups were investigated using electron backscatter diffraction. Increased deformation rate is important to activate tensile twins both near the bent and flange areas. Ingot casted sheets revealed more tensile twins than twin-roll casted sheets. Increased working temperature is important to activate non-basal slips and produce the DRXed grain structure in the flange. Dynamic recrystallization were frequently found in the top flanges of the cups. Both tensile twins and non-basal slips contributed to occurrence of the dynamic recrystallization in the flange.

This paper demonstrates the application of multi-axial diagonal forging (MADF) for fabricating very-high-strength pure Cu with a fine-grained microstructure. Pure Cu subjected to 1 MADF cycle, which comprises 6 passes of multi-axial forging operations and 6 subsequent passes of diagonal forging operations, has a tensile yield strength, ultimate tensile strength, and elongation of 397 MPa, 436 MPa, and 15.7%, respectively. This high strength is attributed to the combined effects of considerably refined grains resulting from continuous dynamic recrystallization during MADF and high dislocation density induced by large imposed strains. With increasing number of MADF cycles, the average grain size and microstructural homogeneity of the multi-axial diagonal forged samples gradually decreases and improves, respectively.

Smart phones and tablets, phones, calendars are the necessities of a modern man. They are one of the MN (Mobile Node), each with wireless network capabilities. The necessities of a modern human MNs are almost included cellular modules available in LTE/3G and Wi-Fi module for high-speed Internet. Until now, MN mobility management is handled, but by using network-based mobility management in this paper. Then, carriers can manage and maintain the network in low-cost. In addition, it was considered that use a lot of modern people with Wi-Fi and LTE/3G, and using Cross-Layer-Based handoff.

ZK60 (Mg–Zn–Zr) alloys exhibited a variation in precipitates with aging, and their mechanical properties also changed. Microindentation tests were carried out on two types of ZK60 alloys of solid solution (T4) and peak aging (T6). Microstructure and texture evolution during indentation was investigated using electron backscatter diffraction. Twinning occurred near the indentation marks in most grains. It was found that tensile twinning was dominant, and two twin variants were usually observed. Texture and microstructure evolution by twinning and slip activation was further examined by uniaxial compression test with strain. The initial random orientation gradually changed into basal fibers with strain. Some grains with nonbasal orientations aligned with the loading direction easily underwent twinning followed by slip deformation. Other grains near basal orientations revealed only slip deformation.

The electric potential of plasma column is measured with the high voltage probe in a pair of atmospheric plasma jets operated by AC-voltage. According to the polarity of voltage applied to the electrodes, the polarity of plasma column potential has the same polarity of applied voltage. The high potential of plasma column at the side of high voltage electrode is decreased linearly along the plasma column to the ground side. Therefore, the plasma column seams to be a kind of resistor whose resistivity is a few 10s . In the experiment of double-jets system, the polarity of plasma potential is verified to be the same polarity to the applied voltage. When the different voltage polarities are applied to the electrodes of double plasma jets, the attractive force is acted between two plumes at the merged plasma and the plasma potential is measured to be low as a few 10s V. When the same polarity of voltage is applied to the electrode, the repulsive force is acted and the plasma potential is measured to be high as a several 100s V at the merged plumes. In the exposure of plasma plume on the bio-substrate with the double plasma jets, the electric shock and thermal damage might be proportional to the plasma power which is the multiplication of the plasma potential and the plasma current.

In this paper, resistance spot weldability of high-Mn steels were investigated in order to get high reliability in welded joints of automotive components. Microstructural characterizations, cross-tensile test (CTT), microhardness tests of spot welded parts were conducted. The effects of weld current on the microstructural characteristics, mechanical properties, and fracture modes were investigated using optical microscopy (OM) and scanning electron microscopy (SEM). The hardness in the weld nugget was observed to be lower than that in the base metal (BM). In CTT, the failure initiation was observed to occur at the boundary of the weld nugget. Also welding imperfections of welded parts were investigated. Liquation cracking in heat affected zone (HAZ), porosity, and shrinkage cavity were found most common welding defects in welded parts. Furthermore, the effects of welding imperfections on weld quality and failure criteria were identified and discussed.

이 연구는 엘리트스포츠 성공요인의 이론적 탐구를 실시하는데 주된 목적이 있다. 이를 위해, 다양한 요인들 중에서도 논의의 초점을 중시적(meso-level) 측면에서의 스포츠정책 요소 및 정책분석 틀(framework)에 대한 최근의 연구 동향을 중심으로 이론적 고찰을 시도하였다. 이 연구는 크게 3단계의 연구맥락에 따라 진행되었다. 첫째, 엘리트스포츠 성공(발전) 또는 경기력 성과를 결정하는 다양한 요소들의 세분환 된 이론적, 방법론적 탐구에 대한 세계적 동향을 고찰하였고, 둘째, 이 연구의 핵심적인 부분으로서 중시적(meso-level)인 측면에서 최근 서구의 엘리트스포츠 성공에 영향을 미치는 정책요소 및 틀에 대한 이론적 고찰을 실시하였으며, 셋째, 연구의 마지막 단계에서는 각기 다른 연구자들에 의해 개발되었거나 확인된 정책요소 또는 정책분석틀의 유사성과 상이점에 대한 논의를 통해서 국내 엘리트스포츠 정책 발전 및 연구 분석을 위한 이론적, 정책적 함의를 도출하였다. 이러한 연구맥락을 통해서 결론의 관점에서 제언을 포함하여 엘리트스포츠 성공을 이끄는 정책 요소에 대한 이론적, 정책적 함의는 다음과 같다. 다른 학자들에 의해 확인되거나 개발된 정책요소 내지는 정책 틀 간에는 상당한 유사성이 있음에도 불구하고 상이점이 발견되고 있다는 점에 주목해 볼 때, 우리나라의 실정(국내의 엘리트스포츠 발전과 관련된 문화적 특성을 고려)에 맞는 이론적 분석의 틀을 개발할 필요성이 제기된다. 예를 들어, 이론적 고찰에서 살펴 본 정책요소들에서는 우리나라에서 중요한 정책요소로 고려되고 있는 연금제도 및 각 경기단체가 제공하는 포상금제도 등과 같은 정책요소가 빠져 있음을 상기할때, 경험적 연구를 통해 우리나라의 실정에 맞는 정책요소들을 편입시켜 새로운 정책 분석틀을 개발할 필요성이 제기된다. 그리고 정책적 함의의 관점은 다음으로 집약된다. 각기 다른 연구자들에 의해 개발되었거나 확인된 정책요소 및 정책 틀 간에는 상당한 유사성이 발견되고 있는데, 이는 국가들 간에 정책학습 내지는 벤치마킹을 하고 있기 때문인 것으로 판단할 수 있다. 이러한 의미는 많은 국가들이 자국의 엘리트스포츠 성공을 이끌기 위해 대체로 합의된 정책요소들에 국가적 재원과 정책적 관심을 모으고 있다는 점이다. 이러한 점에서, 우리나라의 대한체육회가 지속적인 엘리트스포츠 발전을 꾀하여 세계10위의 경기력을 유지시키기 위한 하나의 전략으로서, 위에서 살펴본 정책요소들 내지는 정책 틀을 기초로 각 경기단체에 성과지표를 규정화하고 평가 시스템을 구축한다면 보다 선진적인 정책발전 시스템으로 거듭나리라 판단된다.

이 연구는 미국, 호주, 영국의 엘리트운동선수들을 위한 경력개발 및 진로전환 지원 프로그램의 비교·분석을 통해 얻어진 결과를 바탕으로 국내 정책수립에 기초가 될 정책적 함의 및 대안을 도출하고자 하였다. 이에 이 연구는 크게 3단계의 연구맥락에 따라 진행하였다. 첫째, 국가 간 기술적인(descriptive) 비교를 하기 전경력개발 및 진로전환 관련 지원 프로그램의 세계적인 정책 동향을 고찰하였으며, 둘째, 이 연구의 핵심적인 부분으로서 다수-사례연구(multiple-case study)방법을 채택하여 국가 간 비교연구를 하였으며, 셋째, 연구의 마지막 단계에서는 국가 간 비교·분석을 통해 얻어진 결과를 통해 국내 관련 정책 수립에 기초가 될 수 있는 정책적 함의 및 대안을 도출하고자 하였다. 이러한 일련의 연구방법을 통해서 얻어진 결론은 2개의 정책 적 함의와 3개의 대안으로 결론지어졌다. 첫째, 엘리트스포츠경기력 향상을 위한 유인정책의 집중된 패러다임으로부터 탈피하여 엘리트운동선수들의 자아발전과 균형 있는 삶의 영위를 고려하는 정책 패러다임으로의 보다 근본적인 인식의 변화가 이루어져야 한다. 둘째, 국가대표 출신 은퇴선수를 대상으로 하는 재정지원 위주의 제도적 지원에서 벗어나 엘리트운동선수들의 전반적인 삶을 지원하는 프로그램이 추진되어야 할 것이다. 그리고 위의 첫 번째와 두 번째에 제시된 정책적 함의를 토대로 도출된 구체적인 대안은 다음과 같다. 첫째, 호주의 사례에서 언급된 The Elite Athlete Friendly University(EAFU) 프로젝트가 유용한 정책대안이 될 수 있을 것으로 판단된다. 둘째, 대한올림픽위원회가 Adeco기업과의 협약을 맺는 것을 검토할 필요성이 제기된 다. 셋째, 엘리트운동선수들을 위한 경력개발 및 진로전환 지원프로그램을 담당할 상담전문가 내지는 전문코디네이터를 양성할 필요가 있다.