• Journal of Mechanical Science and Technology
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• 제17권7호
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• pp.1036-1043
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• 2003

A computer simulation method for investigating the form generation mechanism in the centerless through-feed grinding process is described. The length of the contact line and the magnitude of the grinding force between the grinding wheel and workpieces, vary with the change in the axial location of the current workpiece during grinding. Thus, a new coordinate system and a grinding force curve of previous and/or following workpieces are introduced to treat the axial motion. Experiments and computer simulations were carried out using four types of cylindrical workpiece shapes. To validate this model, simulation results are compared with the experimental results.

• 한국정밀공학회지
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• 제10권4호
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• pp.73-80
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• 1993

There and two important variables in machining process control, which are feed and cutting speed. It is possible to improve the machining accuracy and the productivity by maintaining the optimal feed and cutting speed. In this work, a controller is designed to achieve on-line cutting force control based on the modeling of cutting process dynamics established through step response test. Two schemes are proposed and implemented. The first is feed control under the constant spindle speed and the second is spindle speed control under the constant feed. Finally, both are proved to work properly through simulation and experimentation.

• 한국공작기계학회논문집
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• 제11권2호
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• pp.103-111
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• 2002

Out of all metal-cutting process, the hole-making process is the most widely used. It is estimated to be more than 30% of the total metal-cutting process. It is therefore desirable to monitor and detect drill wear during the hole-drilling process. One important aspect in controlling the drilling process is monitoring drill wear status. There are two systems, Basic system and Online system, to detect the drill wear. Basic system comprised of spindle rotational speed, feed rates, thrust torque and flank wear measured by tool microscope. Outline system comprised of spindle rotational speed feed rates, AE signal, flank wear area measured by computer vision, On-line monitoring system does not need to stop the process to inspect drill wear. Backpropagation neural networks (BPNs) were used for on-line detection of drill wear. The output was the drill wear state which was either usable or failure. This paper deals with an on-line drill wear monitoring system to fit the detection of the abnormal tool state.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.821-826
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• 2001

Out of all metal-cutting processes, the hole-making process is the most widely used. It is estimated to be more than 30% of the total metal-cutting process. It is therefore desirable to monitor and detect drill wear during the hole-drilling process. One important aspect in controlling the drilling process is monitoring drill wear status. Accordingly, this paper deals with Basic system and Online system. Basic system comprised of spindle rotational speed, feed rates, thrust, torque and flank wear measured tool microscope. Online system comprised of spindle rotational speed, feed rates, AE signal, flank wear area measured computer vision. On-line monitoring system does not need to stop the process to inspect drill wear. Backpropagation neural networks (BPNs) were used for on-line detection of drill wear. This paper deals with an on-line drill wear monitoring system to fit the detection of the abnormal tool state.

• 한국통신학회논문지
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• 제26권11C호
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• pp.75-84
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• 2001

본 논문에서는 신경망을 이용한 실시간 고장 검출 및 진단(FDD : Fault Detection and Diagnosis) 시스템을 제안한다. 제안된 시스템은 공조 시스템(FDD : Air Handling Unit)에서 발생 가능한 여러 고장들을 검출하고 진단할 수 있다. 고장 검출 및 진단 기법으로 3층 구조의 전방향(feed-forward) 신경망을 사용하였고, 여기에 사용된 학습 방법은 역전파(back-propagation) 학습 알고리즘이다. 공조 시스템에 적용된 실시간 고장 검출 및 진단 시스템은 비주얼 C++와 비주얼 베이직을 사용하여 구현하였다. 제안된 고장 검출 및 진단 시스템을 실제 운전 중인 공조 시스템에 적용하여 실험하였고, 정확한 고장 검출 및 진단이 수행됨을 실험 결과로서 입증하였다.

• 대한전자공학회논문지SD
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• 제45권1호
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• pp.20-27
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• 2008

본 논문에서는 비선형 패턴 분류를 위해 FPGA 칩에 신경회로망을 구현하였다. 병렬처리 연산을 위해 순방향 신경회로망이 구현 되었다. 신경망의 학습을 off-line으로 한 다음에 가중치 값들을 저장하여 사용한다. 예로서, AND와 XOR 논리의 패턴 구분이 수행된다. 실험결과를 통해 FPGA에 구현된 신경회로망이 잘 작동하는 것을 검증하였다.

• 한국전자파학회논문지
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• 제15권7호
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• pp.653-660
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• 2004

본 논문에서는 단락된 사각 디스크와 프로브 급전된 사각 스파이럴 형태의 스트립 선로를 전자기적으로 결합한 형태의 소형 모노폴 안테나를 제안하고, 집중소자를 이용하여 안테나의 등가모델을 제시하였다. 단락 된 사각 디스크는 캐패시턴스 성분을 가지는 모노폴로써 병렬 RLC 공진회로로 등가화 되며, 사각 스파이럴 스트립 선로 급전부는 인덕턴스 성분의 모노폴로써 직렬 RLC 공진회로로 등가화 된다. 그러므로 안테나는 병렬 공진회로의 공진과 직렬 공진회로의 공진이 결합하여 넓은 주파수 대역폭을 가지게 된다. 제안한 안테나는 0.075λ$_{0}$${\times}$0.075λ$_{0}$${\times}$0.075λ$_{0}$의 크기를 가지며, VSWR$\leq$2를 기준으로 2.038GHz의 중심주파수에서 16.5 %의 대역폭을 가진다.

• 한국기계가공학회지
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• 제18권11호
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• pp.1-8
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• 2019

In this study, we design the feed system and process conditions for a lamp garnish lens of an automobile. For this purpose, four design alternatives are presented and injection molding simulation analyses are performed. The optimal feed system is selected by considering the formability of the product and the cost of mold manufacture. The product formability is assessed by the weld line, warpage, sink mark and the maximum injection pressure, whereas the mold-making cost is estimated by the number of valve gates in the hot runner system. To improve the product formability, process conditions are optimized using an experimental design approach named one-factor-at-a-time. No weld line is generated as a result of the optimization. In addition, it is found the warpage and sink mark are reduced while the maximum injection pressure is increased, compared with those before the optimization.

• Journal of Animal Science and Technology
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• 제66권3호
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• pp.555-566
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• 2024

The aim of the present experiment was to determine the standardized ileal digestible (SID) methionine (Met) requirement during the grower phase (22 to 29 days). A total of 192 Ross 308 male broilers (745 ± 50.5 g) were assigned to six dietary treatments in a randomized complete block design, with eight replicate cages per treatment. The experimental diets were formulated based on corn, soybean meal, and synthetic amino acids (AA), with different levels of dietary SID Met ranging from 0.40% to 0.65%, in increments of 0.05%. Individual body weight and feed intake per cage were measured at the beginning and end of the experimental period. Weight gain (g/bird), feed intake (g/bird), gain-to-feed ratio (g/kg), feather weight (g), and relative feather percentage (% of body weight) were analyzed for linear or quadratic responses using orthogonal polynomial contrasts. Final body weight, weight gain, and feed intake increased quadratically as dietary SID Met concentration increased (p < 0.05). However, the composition of AA in the feathers showed no quadratic or linear effect based on dietary SID Met concentrations, except for Ile (p = 0.05; quadratic). The SID Met requirements for optimum and maximum weight gain of 22 to 29-days-old male broilers were estimated using the broken-line and quadratic-line models to 0.45% and 0.55%, respectively.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.288-293
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• 2001

This paper presents the water-hammer effect due to the rapid opening and closing of isolation valve and thruster valve in the spacecraft propulsion system. The single propellant feed system was modeled to investigate the maximum peak pressure due to the water-hammer effect. The test parameters are tank supply pressure, shape and throat length of orifice and line length. Kerosene was used as the inert simulant propellant liquid instead of hydrazine. As downstream line length after isolation valve increased from 1.5 to 2.5m, the maximum line-filling water-hammer peak pressure decreased, but the average time interval between peak pressures increased. The maximum line-filling water-hammer peak pressure with orifice was lower than without orifice, and the maximum line-filling water-hammer peak pressure with orifice at the back of isolation valve was lower than with orifice in front of isolation valve. Without orifice, the maximum water-hammer peak pressure due to the rapid opening and closing of the thruster valve was about 126% of tank supply pressure. With orifice, it decreased. As orifice throat length increased, it decreased. The maximum water-hammer peak pressure due to the rapid closing of the thruster valve with converging-diverging orifice was lower than normal orifice. It was found that the orifice as a means of pressure drop was very effective to reduce the water hammer peak pressure at the thruster valve. The results of this study can be used for the design of spacecraft liquid propulsion feed system.