• 한국기계가공학회지
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• 제19권7호
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• pp.52-59
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• 2020

Automatic tool changers (ATCs) can be divided into drum and chain types. Drum-type ATCs contain a magazine, where the tools are mounted, and a cam gearbox, which swaps the tools via roller gear and grooved plate cams. Drum-type ATCs are advantageous in that the operating time for the tool magazine is more rapid than that of chain-type ATCs and the length of the unit is shorter. Thus, drum-type ATCs can be fabricated into various shapes and forms depending on the number of tools and the magazine size in accordance with machining center requirements and consumer demand. In particular, the price competitiveness of a machining center with a drum-type ATC is higher, while drum-type ATCs are more rigid with fewer parts, possibly reducing the need for regular servicing. This study aims to verify the structural stability and design validity of the magazine base, which is the main structure of a drum-type ATC, using finite element analysis. This study kinematically verifies the specifications of the selected drive motor and reducer and assessed the design of the cam gearbox. It also conducts a structural analysis of the roller camp, which is the core component of the cam gearbox, based on the results of the kinetodynamic analysis, thus validating the structural design.

• 대한세포병리학회지
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• 제2권2호
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• pp.111-118
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• 1991

Fine needle aspiration biopsy cytology (FNA) is an important diagnostic tool in the management of thyroid nodule. Especially, papillary carcinoma of the thyroid has distinct morphologic features that allow a definite cytologic diagnosis with high degree of accuracy. We examined the characteristic cytologic features of 57 cases of papillary carcinoma of the thyroid, and their frequency and diagnostic significance were evaluated. The results obtained are summerized as follows; 1. In pattern of cellular arrangement, papillary structure with or without stroma is predominant feature (96%). 2. In individual cell morphology, grooved nuclei (95%), intranuclear cytoplasmic invagination (89%) and nuclear lobulation (74%) are most frequent and important cytologic findings. 3. Chromatin pattern is usually fine. Coarse chromatin is infrequent finding (37%). Nucleoli are inconspicuous. Cytoplasm us plump and distinctly eosinophilic. 4. Psammoma bodies are identified only in 4 cases (7%), but they are considered as helpful diagnostic features. 5. There are other associated findings including multinucleated giant cells (51%), macrophages (37%) and cystic degeneration (16%).

• 한국정밀공학회지
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• 제18권12호
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• pp.177-184
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• 2001

C3M(chemical mechanical micro machining) is applied for diminishing the size of burr and fabricating the massless patterning for aluminium wafer(thickness of 1${\mu}m$). It is difficult to perform the micro size machining with the radically increased shear stress. While the miniaturization and function-orientation of parts has been needed in the many field such as electronics, optics and medicine. etc., it is not enough to satisfy the industry needs in the machining technology. In this paper feasibility test of diminishing burr and fabricating maskless pattern was experimented and analyzed. In the experiment oxide layer was farmed on the aluminium with chemical reaction by ${HNO_3}$(10wt%), then the surface was grooved with tungsten carbide tool for the different condition such as the load and fred rate. The result was compared with the conventional machining to show the improvement of C3M with SEM for burr diminish and XPS for atomic existence, AFM for more precise image.

• 대한통합의학회지
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• 제9권1호
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• pp.13-22
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• 2021

Purpose : The purpose of this study was to investigate the effects of a virtual reality-based occupational therapy program on the physical function and learning ability of intellectually disabled school-aged children. Methods : In this study, 20 intellectually disabled children of school age were randomly and evenly divided into experimental and control groups with children in the experimental group receiving a virtual reality-based occupational therapy intervention. The study adopted a pretest-posttest design. The intervention was conducted for a total of 12 sessions for six weeks, twice a week, and 50 minutes per session. As measurement tools, BOT-2 and grooved pegboard tests were used to compare physical function before and after the intervention program, and K-ABC was used to check changes in learning ability. Results : The occupational therapy program produced a significant improvement in both physical function and learning ability of the experimental group. A significant difference was observed between the experimental and control groups. Conclusion : This study confirmed the value and usefulness of virtual reality-based occupational therapy as a tool for enhancing the physical function and learning ability of intellectually disabled school-aged children. Based on the results, a variety of future studies are encouraged that would further test the effects of the occupational therapy program used here.