• 한국정밀공학회지
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• 제33권2호
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• pp.95-100
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• 2016

Various processes have been developed to improve the performance of the lubrication oil pump in a recent automobile industry. In particular, trochoidal profile has been widely used for the lubrication oil pump because it is easy to flow control and a lot of oil feed rate is obtained. Accuracy of the trochoidal profile as a core component of the lubricating oil pump affects the driving performance. So, it is necessary to develop efficient processing of the trochoidal profile. In this study, a machining process for the trochoidal profile is developed by turn-mill. Cutting force, surface roughness and tool wear were evaluated in accordance with machining conditions.

• 한국생산제조학회지
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• 제22권2호
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• pp.179-184
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• 2013

In this article, we introduce the study case of technology that can automatically compensate the errors of these factors of a machine during processing on the machine tool's CNC(Computerized Numerical Controller) in real time. The biggest factors that lower the machining accuracy are thermal deformation and chatter vibration. This study is related to the detection and compensation of thermal deformation and chatter vibration that can compensate for faster and produce processed goods with more precision by autonomous compensation. In addition, this study is related to the active control of vibration during machining, monitoring of cutting force and auto recognition of machining axes origin. Thus, we attempt to introduce the related contents of the development we have made in this article.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.329-329
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• 2000

In this paper, a spindle system using an electromagnetic exciter is proposed to compensate a spindle disturbance such as unbalance and machining force etc A spindle compliance can be readily varied with a disturbance which is generated by the interact ion between the spindle / workpiece structure and the cutting process dynamics. The varied compliance is one of the major constraints that deteriorates the surface quality of workpiece. This paper suggests a compliance compensation by using the EME in the proposed spindle system. To compensate the varied compliance, firstly a spindle system modeling was conducted by using the bond graph. Then the model is simulated by numerical analysis method and an optimal EME position is determined to compensate a disturbance effectively through simulation, which makes the bearing load to be minimized

• 한국정밀공학회지
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• 제33권6호
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• pp.453-458
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• 2016

CFRP (Carbon Fiber Reinforced Plastic) and CFRP-metal stacks have recently been widely used in the aerospace and automobile industries. When CFRP is machined by a brittle fracture mechanism, defect generation behaviors are different from those associated with metal cutting. The machining quality is strongly dependent on the properties of CFRP materials. Therefore, process control for CFRP machining is necessary to minimize the defects of differently manufactured CFRPs. In this study, defects in drilling of CFRP substrates with a variety of fiber directions and resin types are compared with respect to thrust force. An experimental study on material interface detection is carried out to investigate its benefits in process control.

• 한국식품영양과학회지
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• 제32권1호
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• pp.67-74
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• 2003

국내산 밀품종인 그루밀과 탑동밀의 성분분석과 수입밀과 전분의 대체 비율 또는 가수량을 달리 하였을 때의 반죽 및 국수의 품질특성을 살펴보았다. 국내산 밀가루는 수입 연질밀에 비해 단백질과 회분함량이 높았다. 국내산 밀가루반죽은 수입밀보다 수분흡수율과 반죽도달시간이 높게 나타났으며, 안정도는 낮고 약화도가 높게 나타났다. 탑동밀의 반죽형성시간이 가장 높았으며, 그루밀이 가장 짧게 나타남으로써 연질밀일수록 반죽형성시간이 짧게 나타남을 알 수 있었다. 탑동과 그루밀에 수입밀 혼합량이 증가함에 따라 수분 흡수율은 감소되는 경향을 보였으며, 반죽형성시간은 탑동밀에 수입밀 30% 대체까지는 감소하였다. 수입 산 밀가루의 첨가는 국내산 탑동과 그루밀의 연화를 감소시켰으며, 가수량이 증가함에 따라 전 시료의 점착성이 증가하였는데, 특히 그루밀의 가수량 65%, 10~20% 수입밀 혼합시 가장 점착성이 높게 나타났다 견고성은 가수량이 증가할수록 감소하였고, 품종별로는 탑동밀이 수입산 밀가루에 비하여 높은 견고성 을 보였다. 국수의 기계적인 조직감은 탑동밀에 수입 밀의 첨가는 인장력은 증가하고 인장길이는 감소되었으며, 그루밀은 이와는 반대의 경향이 나타났다. 국수의 견고성은 대조구(수입산 밀가루)>탑동>그루밀 순서였으나, 수입산 전분 첨 가량이 증가함에 따라 품종에 관계없이 견고성, 부착성및 씹힘성 모두 증가하였고, 3%이상 첨가시 대조구와 거의 비슷한 경도를 나타내었다. 전분의 첨가에 따른 조리된 국수가닥의 인장력은 대조구인 수입산 밀가루에 비하여 탑동과 그루밀에서 비교적 낮은 값을 보였고, 인장길이는 대조구에비하여 전반적으로 늘어나지 않아 국내산 밀이 대조구보다 쉽게 끊어지고 늘어나지도 않음을 알 수 있었다 따라서 그루와 같은 한국산 연질밀은 아밀로즈 함량이 높거나 단백 질함량이 상대적으로 낮은 밀가루를 혼용한다면 수입밀에 뒤지지 않는 제면 성질을 가지며 유연성을 더욱 향상시킬 수 있음을 알 수 있었다.

• 한국식품조리과학회지
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• 제27권3호
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• pp.59-70
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• 2011

The effects of Backryeoncho (Opuntia ficus-indica var. saboten) powder addition (0, 0.4, 0.8, and 1.2%) on the pH, titratable acidity, lactic acid contents, microbial contents, texture, and sensory evaluation of cabbage Kimchi, stored at $10^{\circ}C$ for 36 days were studied to establish an optimum recipe. Upon addition of Backryeoncho powder, pH was higher than that of Kimchi without powder after 36 days of fermentation. The titratable acidity was increased by the addition of Backryeoncho powder, and 0.4% powder added Kimchi showed the slowest changing level. During the fermentation period, the degree of salinity decreased with the addition of powder from 2.52 to 2.19 to 2.10. The a value was higher in Kimchi with added Backryeoncho powder in a dose-dependent manner compared with control Kimchi. The cutting force and compression force were higher during the fermentation period, and especially addition of 0.4% powder showed the highest value of hardness. The addition of powder slowed growth of lactic acid bacteria as compared with the control samples. In the sensory evaluation of overall taste, 0.4% addition of powder improved the quality of Kimchi. Therefore, addition of 0.4% Backryeoncho powder apears to be an acceptable approach to enhance the quality of Kimchi without reducing acceptability.

• 한국생활과학회지
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• 제23권3호
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• pp.467-481
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• 2014

We investigated the effects of Mulberry leaves fermented enzyme liquid(MLE) addition on the quality of Kimchi which were fermented at $5^{\circ}C$ during 30 days. MLE was added to salted cabbage at concentrations of 0%(C), 0.4%(MLE1), 0.8%(MLE2), and 1.2%(MLE3) (w/w). pH in Kimchi added upon 1.2% of MLE, was higher than that of Kimchi without MLE after 12 days of fermentation. The titratable acidity was increased by the addition of MLE, and particularly Kimchi added 1.2% of MLE showed the slowest changed level. The degree of salinity were decreased in Kimchi with MLE as well as control group. However, MLE1 showed significantly lower salinity than MLE2, MLE3 and control group (p<0.001). L, a, b values of control group indicated significantly higher than the Kimchi with enzyme liquid concentrations(MLE1~MLE3). As compared with the control group, the cutting force in treated groups were increased during the fermentation period, and especially MLE3 showed the highest value of hardness. Moreover, that growth of lactic acid bacteria and total bacteria were inhibited by the addition of MLE. In the sensory assessment, the color, taste, and overall preferences were higher in MLE2 than control group and MLE1, MLE3. The acceptability of MLE as an additive in Kimchi among middle school students was higher than in the control sample, with an optimum additive of 0.8% MLE, based on the lowest volume of leftovers. Therefore, it was confirmed that addition of 0.8% MLE appears to be an acceptable approach to enhance the quality of Kimchi without reduction of acceptability.

• 실천공학교육논문지
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• 제13권2호
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• pp.327-332
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• 2021

교육용으로 사용되는 피삭재(소재)는 SM20C, Al6061, 아크릴 등의 소재를 사용한다. SM20C 소재는 탄소강으로서 자격증 시험 및 기능경기대회에서 많이 사용되지만 산업현장에서도 많이 사용된다. Al6061 소재는 탄소강에 비하여 경도가 낮아지고 전성(연성)이 강한 소재이기에 공구의 구성인선이 많이 발생하는 소재 라고 한다. 아크릴 소재를 이용하여 학생들에게 실습지도 하면 어느 부분에서 과다 절삭으로 인하여 진동이 발생하고 공구의 파손이 발생하는 소재이다. 이러한 과정에서 5축장비인 2NC헤드에게 가해지는 충격이 정밀도 제어에는 어느정도 영향을 줄 수 있는지 알아본다. 5축장비의 가장 취약한 부분은 AC축을 제어하는 헤드가 가장 약한 부분이라 할 수 있다. 이 부분의 정밀도 및 누적 공차가 발생할 경우 모든 제품의 정밀도가 떨어지는 현상이 발생한다. 따라서 2NC헤드의 핵심적인 부분, 스핀들 하우징은 Al7075 T6(미국 알코아사) 소재를 사용하고 전체 바디는 FCD450 (구상흑연주철) 사용하여 진행하였다. 이 두가지 소재에서 작용되는 진동 및 절삭 과정에서 힘을 극한조건에서 유한요소 해석으로 적용되는 값을 밝혀 내고자 해석을 진행하였다. 이러한 해석 데이터를 활용하여 학생들이 5축절삭 보다 5축 가공기의 구조를 보고 이해하는데 도움이 되기를 기대한다.

• International Journal of Precision Engineering and Manufacturing
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• 제9권4호
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• pp.74-78
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• 2008

High-speed tool steels are extensively used in tooling industries for manufacturing cutting tools, forming tools, and rolls. Electrical discharge machining (EDM) has been found to be an effective process for machining these extremely hard and difficult-to-cut materials. Extensive research has been conducted to identify the optimum machining parameters for EDM with different tool steels. This paper presents a fundamental study of the surface characteristics of SKH-51 tool steel machined by micro-EDM, with particular focus on obtaining a better surface finish. An RC pulse generator was used to obtain a better surface finish as it produces fine discharge craters. The main operating parameters studied were the gap voltage and the capacitance while the resistance and other gap control parameters were kept constant. A negative tungsten electrode was used in this study. The micro-EDM performance was analyzed by atomic force microscopy to determine the average surface roughness and the distance between the highest peak and lowest valley. The topography of the machined surface was observed using a scanning electron microscope and a digital optical microscope.

• 동아시아식생활학회지
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• 제24권6호
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• pp.827-836
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• 2014

In this study, the effects of Mulberry leaves extract (ME) addition on the quality of Kimchi was investigated during 30 days of fermentation at $5^{\circ}C$. ME was added to salted cabbage at concentrations of 0% (C), 0.4% (ME1), 0.8% (ME2) and 1.2% (ME3) (w/w). The pH of Kimchi added above 0.8% ME was higher than that of Kimchi without ME after 12 days of fermentation. During overall fermentation, the titratable acidity of Kimchi with 1.2% ME remained at the lowest level. The degree of salinity decreased with increasing amount of added ME, whereas control groups showed the highest salinity. In L, a and b values of samples, the highest Figures of L and b were observed in control groups, and ME3 showed the highest value of a. In addition, the cutting force during the fermentation period was higher in all treated groups compared with control groups, and ME3 showed the highest hardness value. Moreover, growth of lactic acid bacteria and total bacteria were inhibited by addition of ME. In the sensory assessment, 0.4% ME improved the quality of Kimchi, showing the highest taste score and overall preference. Therefore, addition of 0.4% ME appears to be an acceptable approach to enhance the quality of Kimchi without reduction of acceptability.