• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.555-559
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• 2001

Feed and spindle motor currents are used toi monitor the cutting process practically. The sensitivity of spindle drive system is lower than that of feed drive system, but the cutting torque is represented well by the spindle motor current. During multi-axis cutting, it is difficult to calculate the resultant cutting force using feed motor currents, because each feed force is reflected by each axis feed motor current with different time delay. It is also difficult to compensate the frictional torque using the feed motor current, because the magnitude of the frictional torque is dependent of the feedrate, table position, and cutting direction. On the other hand, cutting torque can be estimated well using spindle motor current which is independent of the cutting direction.

• Fisheries and Aquatic Sciences
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• 제25권12호
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• pp.619-625
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• 2022

The study carried out a 15-day feeding trial of the fleshy shrimp broodstock that have just finished their first spawn using five different maturation feed types (three types of manufactured feed, fresh feed, and commercial feed) to induce multiple spawning in the shrimp and then analyzed and compared hemolymph levels of total protein, total lipid, hemocyanin, glucose, and cholesterol as well as ovary histology between the treatments to identify the potential of the experimental diets to be utilized as maturation feed. The study found that the manufactured diets of polychaetes + clam and polychaetes + clam + squid resulted in significantly higher levels of lipid and protein in shrimp hemolymph suggesting an indicator of multiple spawning in the fleshy shrimp. The other manufactured diet of polychaets + squid led to the highest 2nd spawning with significantly lower levels of lipid, protein, and cholesterol in shrimp hemolymph. The fresh feed treatment showed similar hematological as well as histological responses to the manufactured diet of polychaetes + squid, but with a significantly lower spawning volume compared to the other treatments. The study demonstrated that the manufactured diets could replace fresh feed as maturation feed and attain a higher shrimp maturation than the commercial feed.

• Asian-Australasian Journal of Animal Sciences
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• 제16권2호
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• pp.282-289
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• 2003

Animal feed additives are used worldwide for many different reasons. Some help to cover the needs of essential nutrients and others to increase growth performance, feed intake and therefore optimize feed utilization. The health status of animals with a high growth performance is a predominant argument in the choice of feed additives. The use of feed additives is more and more questioned by the consumers. Therefore, the feed industry is highly interested in valuable alternatives which could be accepted by the consumers. Probiotics, prebiotics, enzymes and highly available minerals as well as herbs can be seen as alternatives. Herbs, spices and their extracts (botanicals) have a wide range of activities. They can stimulate feed intake and endogenous secretions or have antimicrobial, coccidiostatic or anthelmintic activity. A major field of application of herbs is the protection of animals and their products against oxidation.

• 한국정밀공학회지
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• 제14권4호
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• pp.78-87
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• 1997

In machine tools, frictional force exists between the table and the guideways, and in ballscrews. In this paper, feed motor current measured by a hall sensor is used to calculate the motor torque. Some frictional phenomena are studied in feed drive systems, such as the relationship between feedrate and frictional torque, and chip cover effects on frictional torque. Considering frictional phenomena, the relation- ship between the feed froce and the feed motor current id obtained. Feed force can be well estimated by feed motor current measurement considering frictional behavior. The relationship between the cutting force and the feed motor current is slightly different between up milling and down milling due to the effect of y direc- tional cutting force on frictional torque.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.457-458
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• 2006

A method for obtaining smooth, jerk bounded feed rate profile in high speed machining has been developed. This study proposes a NURBS interpolator based on adaptive feed rate control with a well developed look ahead algorithm which takes into account the machining dynamics as well. Limitation of jerk and proportional torque rate result in smoothened loads on the machine which effectively reduces excitation of the resonant frequencies of the machine. It is found that the values of the feed rate of the down stream sharp corner have profound effect on the feed rate of the upstream sharp corners. By using a windowing scheme the feed rate profile obtained after look ahead method is re-interpolated to reduce the jerk related problems. This is compared with the adaptive NURBS interpolator to show the effectiveness of the proposed method. Simulation results indicate that the consideration of 'ripple effect' is important in avoiding jerk and thereby increasing the machining accuracy.

• 대한기계학회논문집A
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• 제20권8호
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• pp.2508-2515
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• 1996

Determination of an optimal feed rate is valuable in the sense of the precision and efficient machining. In this regard, a new surface roughness model for the face milling operation that considered the radial and axal runouts of the inserts in the cutter body was developed. The validity of the model was proved through the cutting experiments, and the model is able to predict the real machined surface roughness exactly with the information of the insert runouts and the cutting conditions. From the estimated surface roughness value, the maximum feed rate that obtains a maximum naterial removal rate under the given surface roughness constraint can be selected by using a bisection method. Therefore, this mehod for optimizing the feed rate can be well applied to the using a bisection method. Therefore, this method for optimizing the feed rate can be well applied to the using selsction of the cutting condition during the NC data generation in CAM.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.263-268
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• 1997

Development of a high speed feed drive system has been a major issue for the past few decades in machine tool industries. The reduction of tool change time as well as repid travel time can enhance the productivity. However,the high speed feed drive system generates more heat in nature,which leads to thermal expansion that has adverse effects on the accuracy of machined part. The paper divides the feed drive system into the ball screw and guide way. For each part, the thermal behvior model is separtately developed to estimate the position error of the respective feed drive system that is caused by the thermal expansion. The modified lumped capacitance method is used to analyze the linear position error of the ball screw. The thermal deformation of guide way parts affects the straightness and angular error as well as linear position error. Finite element method is used to estimate the thermal behavior of these guide way parts. The effectiveness of the proposed models are verified through the experiments using laser interferometer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1667-1668
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• 2008

There are three main devices such as boiler producing steam, turbine driving generator and generator producing electricity. An electrical generator in power plant is driven and maintained its speed at rated by steam turbine which is coupled into generator directly. Turbine auxiliary devices such as condenser, deaerator, feed water heater, gland steam condenser, pump recirculation equipment, feed water pump, and so on should be operated well so that the steam turbine exert its maximum efficiency. There are many control loop such as hot well level and condenser recirculation, deaerator level, pegging steam pressure, feed water heater level, feed water pump recirculation. In this paper condenser level control and deaerator level control are going to be described.

• Asian-Australasian Journal of Animal Sciences
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• 제13권1호
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• pp.86-95
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• 2000

Animal feed additives are used worldwide for many different reasons. Some help to cover the needs of essential nutrients and others to increase growth performance, feed intake and therefore optimize feed utilization. They can positively effect technological properties and product quality. The health status of animals with a high growth performance is a predominant argument in the choice of feed additives. In many countries the use of feed additives is more and more questioned by the consumers: substances such as antibiotics and $\beta$-agonists with expected high risks are banned in animal diets. Therefore, the feed industry is highly interested in valuable alternatives which could be accepted by the consumers. Probiotics, prebiotics, enzymes and highly available minerals as well as herbs can be seen as alternatives to metabolic modifiers and antibiotics.

• 한국수산과학회지
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• 제14권1호
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• pp.29-31
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• 1981

1980년 6월 7일부터 8월 8일까지 실내순환수조에서 고형사료 pellet을 이용한 뱀장어(Anguilla japonica) 사육실험을 했다. 실험에 이용한 뱀장어는 1974년부터 1976년 사이 본 대학에 들어온 것 중에서 성장이 불진하여 남아 있던 것을 이용했다. 실험 결과, 사료계수 $1.05{\sim}1.678$, 일간성장률$0.96{\sim}1.46\%$로 나타났으며, 특히 이 중에서도 가장 작은 것들도 일간성장률 $1.3\%$의 높은 성장률을 나타내었다. 이것은 현재까지 일반 뱀장어 양식에 이용되어온 반죽사료와 비교해 볼 때에 못지않는 충분한 생장이었다. 또한 Pellet을 이용함으로 해서 먹이를 주고 난뒤 수질이 흐려지는 것도 방지할 수 있었다.