• 소성∙가공
• /
• 제27권1호
• /
• pp.18-27
• /
• 2018

As one of the functional metal parts in steam turbine diaphragm assembly, the hollow-partitioned turbine nozzle (stator) has large and thick geometries, as well as an asymmetric configuration. Therefore it is hard to support a metal blank in the die cavity. To ease this situation and control posture and position of metal blank (workpiece), a blank support structure is newly introduced. The blank support structure is basically composed of enlarged arms from the blank, guide pins and linear bearings. It can help to control the intermediate blank without a critical sliding phenomenon. The operation mechanism of this blank support structure, during thick plate forming for the hollow-partitioned turbine nozzle stator, is first evaluated. A series of FEM-based numerical simulations, with respect to the width of the guide arm as geometric design parameters, are carried out to investigate its applicable range. As the results, it is observed the blank support structure for this thick plate forming can guide the workpiece to have stable posture during the plate forming process.

• 소성∙가공
• /
• 제28권6호
• /
• pp.335-346
• /
• 2019

Thick plate forming is presented to manufacture a large and curved member of steam turbine diaphragm. Due to three-dimensional asymmetry of target geometry, it is hard to consistently keep the blank position in die cavity between forming punch and die. In order to relieve the position instability of the blank during the thick plate forming, a blank support structure is proposed to be composed of guide pins and linear bearing, and blank guide arm enlarged from both longitudinal ends of the thick blank. In this study, parametric investigations with regard to the geometric position and width of the blank guide arm are carried out. As main geometric parameters, 2 positions such as maximum curvature region and minimum one on a curved cross-section profile of the target shape are selected, and 14 widths of the blank guide arm are considered. Using 28 variable combinations, three-dimensional numerical simulations are performed to predict the appropriate range of the process parameters. The compatibility and validity of the blank support structure with the blank guide arm for the thick plate forming is verified through the thick plate forming experiments.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.410.1-410.1
• /
• 2016

Vanadium dioxide ($VO_2$) is a well-known material that exhibits a metal-semiconductor transition at 340 K, with drastic change of transmittance at NIR region. However, $VO_2$ based thermochromics accompany with low visible transmittance value and unfavorable color (brownish yellow). Herein, we demonstrate the adjustment of visible transmittance of $VO_2$ thin film by nanosphere template assisted patterning process using sol-gel method. 2-Dimenstional honeycomb shape was varied as function of diameter of nanosphere and coating conditions. The morphological geometry of the films was investigated by FE-SEM and AFM. Result shows that inversed shape of nanosphere was formed clearly and pattern width was altered according to the bead size. This structure creates the geometrical blank area from the position of nanosphere which improves the optical transmittance at the visible region. Moreover, such patterned $VO_2$ thin film not only maintains the optical switching efficiency, but also generate the gorgeous scattering effect which presumably support the glazing application.

• The Journal of Asian Finance, Economics and Business
• /
• 제9권2호
• /
• pp.133-140
• /
• 2022

The impact of State management factors on transfer pricing activities of foreign direct investment enterprises in Vietnam is examined in this study. This adds to the empirical evidence on factors affecting transfer pricing activities of foreign-invested enterprises in Vietnam. A questionnaire survey of officials directly involved in the inspection of transfer pricing activities is used as the research method. The study yielded 226 questionnaires. The author chose 210 questionnaires after deleting those that were ineligible due to a large number of blank cells. The following procedures are used to process the data from the satisfied votes: Cronbach's Alpha test to measure the reliability of the scale; Exploratory factor analysis to break down data into smaller sets of variables to discover the underlying structure; Descriptive analysis to describe the underlying quantitative features of the data; Correlation and regression analysis to evaluate the relationship between variables with the support of SPSS 25 software. Inspection pressure, professional inspector qualifications, and inspector role, State control organization, inspector professionalism, legal corridor on transfer pricing control, macroeconomic situation, and investment environment have a positive impact on state management on transfer price operations, according to research findings. The author has provided solutions to increase the efficiency of State management on transfer pricing operations of foreign-invested businesses in Vietnam based on the research findings.

• 한국산학기술학회논문지
• /
• 제16권9호
• /
• pp.5789-5794
• /
• 2015

최근 스마트 폰, 모바일 PC 제품의 외관에 필요한 가벼운 금속제품으로 제조를 하기 위하여 알루미늄 압출 공정과 CNC 가공기법을 적용한 생산방식이 널리 사용되고 있다. 하지만, 알루미늄 압출법은 외관 디자인의 제약이 있으며, 특히 CNC 가공 프로세스가 상대적으로 높은 생산 비용 및 낮은 생산성으로 생산단가가 많이 높은 단점이 있다. 본 연구에서, 새로운 처리 방법을 순서 재료비를 대폭 감소시키고, 제조 속도를 향상시키기 위해 판재성형과 부피성형의 두가지 공정을 섞어 새로운 판단조 공정을 개발하였다. 새로운 판단조 공법(hybrid plate forging)이란 우선 일반적인 딥드로잉으로 중간 모양을 만든 후 원하는 벽 부위만 증육을 하는 방법을 의미한다. 이러한 판단조 공법을 활용하여 재료의 낭비와 제조 시간을 최소화하는 것이 가능하게 된다. 본 연구에서는 상용 유한 요소 프로그램 AFDEX-2D를 통해 판단조공정을 설계하였고 최적의 사용 가능한 소재의 두께와 초기 폭을 설계하였다. 최종적으로 실제 노트북 케이스 금형을 제작하여 제안한 방법의 타당성을 검증하였다.