• 대한기계학회논문집A
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• 제34권10호
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• pp.1479-1485
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• 2010

최근 와이어의 생산성 및 고강도화를 위한 고탄소강의 고속신선으로 인해 와이어 표면의 급격한 온도상승으로 잔류응력이 크게 증가하는 문제점이 발생되고 있다. 와이어의 다단 신선 공정시에는 소성변형과 마찰열에 의하여 와이어 내부의 온도가 더욱 크게 상승하게 된다. 특히, 고속 신선의 경우 마찰에 의한 온도구배가 더욱 크게 되어 와이어 표면층에 축방향 인장 잔류응력을 과도하게 발생시킨다. 따라서, 본 연구에서는 먼저 표면 온도 상승과 축방향 잔류응력과의 관계를 규명한 다음에 와이어의 평형온도 예측 모델을 제안하고, 이를 토대로 표면 온도 상승에 의한 축방향 잔류응력 예측식을 개발하였다. 고탄소강(0.82%C)소재의 다단신선 실험을 통해 얻어진 시편에 대하여 X 선 회절을 이용하여 잔류응력을 측정하여 제안된 예측식을 검증하였다.

• 한국정밀공학회지
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• 제27권8호
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• pp.70-75
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• 2010

The aim of this study is to evaluate the axial residual stress in multi-pass drawn high carbon steel wire by using FE analysis and XRD. When FE analysis is applied to evaluate the residual stress in drawn wire of multi-pass drawing process, obtaining the reliable effective stress-strain curve at high strain is very important. In this study, a model, which can express the reliable effective stress-strain curve at high strain, is introduced based on the Bridgman correction and tensile test for multi-pass drawn high carbon steel wires. By using the introduced model, FE analysis was carried out to evaluate the axial residual stress in the drawn wires. Finally, the effectiveness of the FE analysis with the introduced stress-strain relation was verified by the measurement of residual stress in the drawn wires through XRD. As a result, the evaluated residual stress of FE analysis shows good agreement with the measured residual stress.

• 소성∙가공
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• 제26권3호
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• pp.162-167
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• 2017

The tensile surface residual stress in the multi-pass drawn wire deteriorates the mechanical properties of the wire. Therefore, the evaluation of the residual stress is very important. Especially, the axial residual stress on the wire surface is the highest. Therefore, the objective of this study was to propose an axial surface residual stress prediction model of the multi-pass drawn steel wire. In order to achieve this objective, an elastoplastic finite element (FE) analysis was carried out to investigate the effect of semi-die angle and reduction ratio of the axial surface residual stress. By using the results of the FE analysis, a surface residual stress prediction model was proposed. In order to verify the effectiveness of the prediction model, the predicted residual stress was compared to that of a wire drawing experiment.

• 소성∙가공
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• 제28권5호
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• pp.275-280
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• 2019

The aim of this study is to fabricate an ultra-fine pure rhodium wire using multi-pass wire drawing process. To manufacture $30{\mu}m$ ultra-fine rhodium wire from the initial $50{\mu}m$ wire, a multi-pass wire drawing process was designed based on the uniform reduction ratio theory. The elastic-plastic finite element analysis was then conducted to validate the efficacy of the designed process. The drawing load, drawing stress, and the distribution of the effective strain were evaluated using the finite element analysis. Finally, the wire drawing experiment was performed to validate the designed wire drawing process. From the results of the experiment, the diameter of the final drawn wire was found to be $29.85{\mu}m$.

• 소성∙가공
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• 제19권4호
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• pp.224-229
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• 2010

During the multi-pass wire drawing process, wires suffer a great amount of plastic deformation that is through the cross-section. This generates tensile residual stress at surface of drawn wires. The generated residual stress on surface is one of the problems for quality of wires so that prediction and reduction of residual stresses is important to avoid unexpected fracture. Therefore, in this study, the effect of process variables such as semi-die angle, bearing length and reduction ratio on the residual stress was evaluated through Finite Element Analysis. Based on the results of the Analysis, a prediction model was established for predicting residual stress on the surface of high carbon steel(AISI1072, AISI1082). To identify the effectiveness of the proposed model, X-ray diffraction is used to measure the residual stresses on the surface. As the result of the comparison between calculated residual stresses and measured residual stresses, the model could be used to predict residual stresses in cold drawn wire.

• Journal of Nutrition and Health
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• 제9권1호
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• pp.76-83
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• 1976

본(本) 연구(硏究)의 목적(目的)은 지역집단(地域集團)의 각(各) 식품군(食品群)에 대한 태도(態度)를 밝혀내고 나아가서는 영양개선사업(營養改善事業)의 평가(評價)와 아울러 특정(特定) 식품(食品)의 섭취량(攝取量의) 차이(差異)에서 기인(起因)하는 영양문제(營養問題)의 적절(適切)한 해결방안(解決方案)을 모색(摸索)키 위한 기초정보(基礎情報)를 제공(提供)키 위(爲)함이다. 이는 1973년 8월 보건사회부(保健社會部)가 서울특별시외(特別市外) 3개도(個道)에서 층별다단추출법(層別多段抽出法)에 의(依)하여 추출한 30지역(地域), 600가구(家口)을 대상(對象)으로 실시(實施)한 국민영양조사중(國民營養調査中) 8개지역(個地域)을 선정(選定)하여 그 중(中), 식품섭취실태조사자료(食品攝取實態調査資料)에 그 근거(根據)를 두고 있다. 각(各) 식품군(食品群)에 대(對)한 전대상지역(全對象地域)의 태도(態度)는 다음과 같다(괄호안은 친지성(親知性) 지수(指數)). 1. 장유류(醬油類) (-1.20) 2. 유지류(油脂類) (-1.12) 3. 두류(豆類) (-0.06) 4. 저장야채(貯藏野菜) (-0.45) 5. 해조류(海藻類) (-0.32) 6. 사당류(砂糖類) (-0.19) 7. 신선야채(新鮮野菜) (-0.15) 8. 미류(米類) (-0.13) 9. 맥류(麥類) (-0.07) 10. 저류(藷類) (-0.06) 11. 선어개류(鮮魚介類) (0.44) 12. 저장어개류(貯藏魚介類) (0.56) 13. 난류(卵類) (1.06) 14. 과실류(果實類) (1.26) 15. 수조육류(獸鳥肉類) (1.33) 16. 유(乳) 및 유제품(乳製品) (2.87) 또한, 지역집단(地域集團)의 식품(食品) 친화도(親和度)는 식품군(食品群)에 따라 매우 유의(有意)한 차이(差異)가 있으나, 지역간(地域間) 차이(差異)는 보이지 않으며, 미류(米類), 맥류(麥類), 두류(豆類), 저류(藷類), 저장야채(貯藏野菜), 과실류(果實類), 해조류(海藻類), 수조육류(獸鳥肉類), 난류(卵類), 선어계류(鮮魚介類) 및 유지류(油脂類)의 섭취량(攝取量)은 지역집단간(地域集團間)에 매우 유의(有意)한 차이(差異)가 있었으나 신선야채(新鮮野菜), 저장어개류(貯藏魚介類), 유(乳) 및 유제품(乳製品)의 경우(境遇)에는 지역집단(地域集團)에 따른 차이(差異)가 나타나지 않았다.