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안주은(Ju Eun An),이성호(Sung Ho Lee),곽재섭(Jae Seob Kwak) 한국생산제조학회 2016 한국생산제조학회지 Vol.25 No.2
A micro end mill is one of the precise tools used in machining ultra-precision products such as microchannel and micropatterned mold. To achieve the required precision of these products, several studies investigated the cutting force, burr formation, and burr generation mechanism of micro end mills; however, there are few studies on the alignment of micro tools, which is the foundation of machining. Hence, in this investigation, relation expressions were derived to determine the relation between the misalignment parameters and the machining accuracy. At the same time, the effect of the machining parameters was analyzed using a multiple linear regression analysis and the analysis of variance. The results indicate that the tilting angle of a micro tool has more influence on the machining accuracy than other parameters.
Tool Wear Rate and Accuracy of Patterns in Micro Prismatic End-milling
Ju-Eun An(안주은),Jung-Hee Lee(이정희),Jae-Seob Kwak(곽재섭) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.3
Micro prism pattern is applying in order to get increase of luminance, control the light, and so forth especially in optics and display industry. Most patterns are fabricated by lithography, planning, and EDM, but they have limitations on the productivity or the unit cost of produce. However, ultra precision mold is one of the processes able to replace it, and assure high productivity required by industries. In this investigation, micro prismatic end-milling is suggested in order to fabricate the pattern effectively. Micro prism pattern having 100μm of pitch and height was machined on STD-11. After machining, the flank and boundary wear on micro end mill were measured and analyzed, as well as burr formation and dimensional accuracy of fabricated pattern were evaluated. Thus the optimal cutting conditions were derived.
A Study on the Characteristics of Share Repurchasing Firms in Korea
Hyun Mo Sung(성현모),Ju Eun An(안주은) 한국로고스경영학회 2021 로고스경영연구 Vol.19 No.1
국내에서 자사주 취득 기업의 수와 자사주 취득 금액은 증가하고 있지만, 자사주 취득 기업의 특성에 대한 합의된 결과는 없다. 따라서 본 연구의 목적은 이러한 특성을 실증적으로 분석하는 것이다. 1996년부터 2016년까지 KOSPI 및 KOSDAQ 시장에 상장된 자사주 취득 기업을 자사주 취득 기업과 규모가 비슷하고 동일한 업종에 속하는 비 자사주 취득 통제 기업과 비교하여 실증적으로 분석하였다. Univariate 분석에 따르면 KOSPI 자사주 취득 기업은 자사주 취득 활동 이전에 통제 기업에 비해 고정 자산이 적고 대주주 지분이 낮으며 현금이 풍부한 기업이었다. 그러나 이들 기업의 현금 풍부성은 높은 수익보다는 고정 자산의 처분에 기인한 것으로 보인다. 또한 KOSDAQ 자사주 취득 기업도 자사주 취득 활동 이전에 통제 기업에 비해 고정 자산이 적고 대주주 지분이 낮으며 현금이 풍부한 기업으로 특징 지어진다. 그러나 현금이 풍부한 이유가 고정 자산의 처분으로 인한 것이 아니고 높은 수익과 영업활동으로 인한 현금 흐름에 기인한 것으로 보인다. KOSPI와 KOSDAQ 자사주 취득 기업의 실증적 결과는 현금이 풍부한 이유가 다름에도 불구하고 잉여 현금 흐름 가설 및 대주주 지분 증대 가설과 일치하지만 신호 가설과는 일치하지 않는다. ven though the number of share repurchasing firms and the amount of share repurchases are increasing in Korea, there is no consensus on the characteristics of share repurchasing firms. Therefore, the purpose of this study was to empirically analyze such characteristics. Share repurchasing firms listed in the KOSPI and KOSDAQ markets from 1996 to 2016 were analytically compared to non-share repurchasing control firms that were similar in size and belonged to the same industry as share repurchasing firms. Univariate analyses revealed that KOSPI share repurchasing firms, before share repurchasing activity, were cash-rich firms with smaller fixed assets and lower major shareholders’ equity relative to the control firms. However, these firms’ cash richness was likely due to the disposal of their fixed assets rather than higher earnings. On the other hand, KOSDAQ share repurchasing firms are also characterized before share repurchasing activity as cash-rich firms with smaller fixed assets and lower major shareholders’ equity relative to their control firms. However, their cash richness is unlikely due to the disposal of their fixed assets but instead to higher earnings and operating cash flows. The empirical results for both KOSPI and KOSDAQ share repurchasing firms are consistent with the free cash flow hypothesis and the major shareholders’ equity enhancement hypothesis, despite different reasons for their cash richness. The signaling hypothesis was not supported by the empirical results.
마이크로 머시닝에서 공구 정렬과 가공정밀도에 관한 연구
진동현(Dong-Hyun Jin),안주은(Ju-Eun An),김주권(Joo-Kwon Kim),이성호(Sung-Ho Lee),손출배(Chul-Bae Son),곽재섭(Jae-Seob Kwak) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Micro end mill is one of the precise tools, which is used in machining of ultra-precision products such as micro channel, micro patterned mold, and so forth. To satisfy the required precision of these products, many studies were investigated on the cutting force, burr formation, and burr generation mechanism of micro end mill, but there are little studies on the alignment of micro tool even which is the foundation of machining. Hence in this investigation, a simulation on manufacturing of channel with misaligned micro end mill was carried out and its effect was evaluated.
글로브 밸브의 누설방지를 위한 시트 설계 및 유한요소해석
이성호(Sung Ho Lee),강경아(Gyeong Ah Kang),곽재섭(Jae-Seob Kwak),안주은(Ju Eun An),진동현(Dong Hyun Jin),김병탁(Byung Tak Kim) 대한기계학회 2016 大韓機械學會論文集A Vol.40 No.1
밸브는 배관의 유량을 차단 및 제어하기 위한 장치로써 게이트 밸브, 글로브 밸브, 체크 밸브 등 많은 종류가 사용되고 있다. 그 중 글로브 밸브는 고압력 조건에서의 유량조절이 용이하여 LNG 선박, 증기 배관 등에 사용된다. 본 논문에서는 글로브 밸브의 누설 문제를 구조적으로 해결하기 위해 시트의 형상을 변형하는 방법을 제시하였다. 또한 유한 요소 해석을 통해 각 모델의 응력분포와 변형량을 비교하고 이를 통하여 제안한 모델에 대한 검증을 진행하였다. 시뮬레이션 결과 제안된 모델에서 원주 방향의 변형이 줄어들고, 누설을 감소시킬 수 있는 Self-supporting 효과를 확인할 수 있었다. The valves used to control or shut off the flow through a pipeline can be divided into many different types, including gate valves, globe valves, and check valves. Globe valves, in particular, have excellent properties, and because they can easily control the flow under high-pressure conditions, they are generally used in LNG ship and steam pipelines. In this paper, a method for changing the shape of a seat was suggested to solve the valve leakage problem from a structural perspective. In addition, the stress distribution and directional deformation were compared for each model. The suggested models were thus validated, and the optimized seat structure, which includes a self-supporting capability for decreasing the amount of leakage, was determined.