• 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.

• Journal of Welding and Joining
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• 제19권5호
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• pp.506-511
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• 2001

Weld overlay has been developed to improve the property of material surface which is used in the severe environment. Weld overlay is the process which uses an arc heat and welds different composition of alloy on the substrate for the improvements of heat resistance and wear resistance. Weld overlay has a lot of advantages which are high hardness, good processing efficiency, easy controlling of layer thickness, good quality and low cost. In this study, weld overlay was performed by MAG welding on the base metal(SS400) with filler metal which contain composite powders(Cr+C+Mn+Mo+NbC) and solid wire(JIS-YGW11). Characterization of hardness and wear resistance were analyzed by EDS, EPMA, XRD and observations of microstructure were performed to investigate characteristics of overlays. The experimental results of overlaid specimens manufactured with Cr+C+Mn+Mo+NbC powders were obtained as fellows. ${\alpha}-phase$, M(Fe, Cr)3C and NbC of overlays were increased with decreasing the wire feed rates and increasing powder feed rates. Also the hardness of overlays were increased and the specific wear were decreased.

• 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.

• Environmental Engineering Research
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• 제10권1호
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• pp.7-14
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• 2005

The feasibility of hydrogen production with a raw seed sludge through direct acclimation of feedstock was investigated at acidogenic stage, and methane was harvested at followed methanogenic stage in an anaerobic two-stage process. Hydrogen content was higher than 57% at all tested organic loading rates (OLRs) and the yield of hydrogen ranged from 1.5 to 2.4 mol H2/mol hexose consumed and peaked at 6 gVSl-1day-1. Normal butyrate and acetate were main volatile fatty acids (VFAs), whereas the concentration of propionate was insignificant. The hydrogen-producing bacteria, Clostridium thermosaccharolyticum, was detected with strong intensity at all tested organic loading rates (OLRs) by denaturing gradient gel electrophoresis (DGGE) of the polymerase chain reaction (PCR) analysis. From COD balance in the process, the fraction of the feed-COD converted to the hydrogen-COD at acidogenic stage ranged from 7.9% to 9.3% and peaked at 6 gVSl-1day-1, whereas the fraction of feed-COD converted to the methane-COD at methanogenic stage ranged from 66.2% to 72.3% and peaked at 3 gVSl-1day-1.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.663-668
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• 2006

In the present paper, a single stage fresh water generator was modified and extended to 2 effect desalination system. The inlet temperatures of hot water and feed water were selected as experiment parameters to get operating conditions and fresh water generating rates. The impacts of these parameters on operating conditions and fresh water generating rates were described in detail.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.801-805
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• 2000

This paper presents a new method of tool path optimization. A NC verification model based Z-map was utilized to obtain chip load in feed per tooth. This developed software can regenerate a NC program from cutting condition and the NC program that was generated in CAM. The regenerated NC program has not only all same data of the ex-NC program but also the new feed rates in every block. The new NC data can reduce the cutting time and manufacture precision dies with the same chip load in feed per tooth. This method can also prevent tool chipping and make constant tool wear. This paper considered the effects of acceleration and deceleration in feed rate change.

• Journal of Computational Design and Engineering
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• 제2권4호
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• pp.206-217
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• 2015

This paper presents a complete S-shape feed rate scheduling approach (CSFA) with confined jerk, acceleration and command feed rate for parametric tool path. For a Non-Uniform Rational B-Spline (NURBS) tool path, the critical points of the tool path where the radius of curvature reaches extreme values are found firstly. Then, the NURBS curve is split into several NURBS sub-curves or blocks by the critical points. A bidirectional scanning strategy with the limitations of chord error, normal/tangential acceleration/jerk and command feed rate is employed to make the feed rate at the junctions between different NURBS blocks continuous. To improve the efficiency of the feed rate scheduling, the NURBS block is classified into three types: short block, medium block and long block. The feed rate profile corresponding to each NURBS block is generated according to the start/end feed rates and the arc length of the block and the limitations of tangential acceleration/jerk. In addition, two compensation strategies are proposed to make the feed rate more continuous and the arc increment more precise. Once the feed rate profile is determined, a second-order Taylor's expansion interpolation method is applied to generate the position commands. Finally, experiments with two free-form NURBS curves are conducted to verify the applicability and accuracy of the proposed method.

• 한국양식학회지
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• 제12권1호
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• pp.25-30
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• 1999

피라미의 종묘를 생산하기 위하여인공부화, 먹이, 성장을 조사하였다. 난황이 갓 흡수된 개체는 전장이 7.6~8.2mm(평균 7.97mm) 이었으며, 부화 후 3일만에 부상하였다. 부상 후 소형 물벼룩, 윤충류, 알테미아를 섭취하였으며, 초기용 인공 분말사료도 섭취하였다. $20~32^{\circ}C$의 온도조건에서 부화시험을 한 결과 부화율은 $26^{\circ}C$에서 가장 높았으며, 47시간이 소요되었다. 부화기의 형태 중에서는 부화병에서 부화율이 89%로 가장 높았으며, 그물상자 및 Californian 부화기에서도 부화율 80% 이상으로 높았다. 부화 후 50일간 사육 한 결과 30.0mm(25.6~32.0mm)로 성장하였다. 온도가 높을수록 자어의 성장이 빨랐는데, 특히 $26^{\circ}C$ 이상에서 성장이 양호하였다. 그러나, 생존율은 $32^{\circ}C$에서 가장 낮았다. 부화직후부터 배합사료만으로서 사육이 가능하였으며 알테미아나 잉어용 사료에 비해서 넙치 및 조피볼락용 사료에서 성장이 양호하였다.

• 한국자동차공학회논문집
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• 제24권1호
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• pp.67-73
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• 2016

The application of titanium has been gradually rising because the utilizing ranges for low weight and high strength are rapidly increased by the need for improving the fuel economy in production industries such as the aviation and automotive in recent. The purpose in this study is to investigate the appropriate cutting conditions on the life of flat and round end mills by measuring the maximum cutting temperature relative to the machining time, and calculating the wear rates of cutting tool with the spindle speed and feed rate of vertical machining center as a parameter in the titanium roughing cut machining which is widely used in critical parts of aircraft, cars, etc. When the wetted roughing cut machining of titanium with a soluble cutting oil is conducted by the flat and round end mills, the maximum cutting temperatures for a variety of spindle speed and feed rate are measured at ten-minute intervals during 60 minutes by an infrared thermometer, and the wear rates of cutting tool are calculated by the weight ratios based on tool wear before and after the experiment. It is found that the maximum cutting temperature and the wear rates of cutting tool are raised as the cutting amount per tool edge is increased with the rise of feed rate, in this experimental range, and as the frictional area due to the rise of contacting friction numbers between tool and specimen is increased with the rises of cutting time and spindle speed. In addition, the increasing rate of maximum cutting temperature in the flat and round end mills are the highest for the cutting time from 50 to 60 minutes, and the wear rate of cutting tool in the flat end mill is 1.14 to 1.55 times higher than that in the round end mill for all experimental conditions.

• Asian-Australasian Journal of Animal Sciences
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• 제16권10호
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• pp.1501-1509
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• 2003

The simultaneous addition of xylanase (5,600 EXU/kg) and phytase (500 FTU/kg) feed enzymes to wheat-based broiler diets was investigated. Starter, grower and finisher diets, with three tiers of nutrient specifications, were fed to 1,440 broiler chicks kept on deep litter from 1-42 days post-hatch, without and with xylanase plus phytase, to determine the effects of diet type and enzyme supplementation on growth performance. The nutrient specifications of type A diets were standard; energy density and protein/amino acid levels were reduced on a least-cost basis to formulate type B diets and further reduced to type C diets. Phosphorus (P) and calcium (Ca) levels were adjusted in supplemented diets. From 1-42 days post-hatch, diet type significantly influenced growth performance. Birds on type C diets had lower growth rates (2,429 vs. 2,631 g/bird; p<0.001), higher feed intakes (4,753 vs. 4,534 g/bird; p<0.005) and less efficient feed conversion (1.96 vs. 1.72; p<0.001) than birds offered type A diets. Enzyme supplementation increased growth rates by 3.2% (2,580 vs. 2,501 g/bird; p<0.005) and improved feed efficiency by 2.7% (1.80 vs. 1.85; p<0.05) over the entire feeding period. There were no interactions between diet type and enzyme supplementation. At 21 days, 5 out of 30 birds per pen were transferred to cages to ascertain treatment effect on apparent metabolisable energy (AME) and nitrogen (N) retention. Xylanase plus phytase enhanced AME (13.48 to 13.91 MJ/kg DM; p<0.001) and N retention (56.3 to 59.7%; p<0.005). Carcass and breast weights of the caged birds were determined following commercial processing. Diet type significantly influenced breast weight, carcass weight and yield. Birds offered Type A diets, in comparison to Type C diets, supported heavier breast (467 vs. 424 g; p<0.001) and carcass weights (1,868 vs. 1,699 g; p<0.001) with superior carcass yields (71.8 vs. 70.6%; p<0.005). Enzyme addition increased carcass weight by 3.9% (1,752 vs. 1,821 g; p<0.005) and breast weight by 5.8% (431 vs. 456 g; p<0.01) without influencing yields. Feed ingredient costs per kg live weight gain and per kg carcass weight indicated that enzyme addition was economically feasible, where supplementation of Type A diets generated the most effective results. Importantly, soluble and total non-starch polysaccharide and phytate contents of the wheat used were typical by local standards. This study confirms the potential of supplementing wheat-based broiler diets with xylanase plus phytase but further investigations are required to define the most appropriate inclusion rates and dietary nutrient specifications in this context.