• Asian-Australasian Journal of Animal Sciences
• /
• 제6권2호
• /
• pp.275-279
• /
• 1993

A study using dairy heifers was conducted to determine the effect of environmental temperature on heat production differing in feed intake level. The design consisted of three levels of feed intake (low, medium and high) and two environmental chamber temperature (15 and $30^{\circ}C$) with four replications in each treatment. Rectal temperature (RT), respiration rate (RR), heart rate (HR) and heat production (HP) were then measured. At the both environmental temperature, RT, RR and HR increased with the increase in feed intake level. The RT and RR also increased with the elevation of environmental temperature. The HP of $30^{\circ}C$ was significantly higher (4.8-8.9%) than $15^{\circ}C$. The estimated metabolizable energy requirement for maintenance (MEm) was higher (p<0.05) at $30^{\circ}C$ ($554.7kJ/kg^{0.75}$ d) than $15^{\circ}C$ (464.9 kJ/kgd). It was suggested that the decreasing in productive efficiency under hot environmental conditions partly associated with the increase in HP, which associated with the change in heat loss mechanism from sensible path to evaporative path.

• 한국정밀공학회지
• /
• 제25권5호
• /
• pp.7-14
• /
• 2008

• Journal of Biosystems Engineering
• /
• 제23권3호
• /
• pp.259-270
• /
• 1998

An automatic seedling transplanter, employed an innovative plug-seedling feeder was developed by improving the problems of conversational feeding and transplanting mechanisms. With conventional methods, missing and damage rates of seedling were high for long seedlings over 20cm and also breaking seed-bed was frequently observed. Thus, a pushout-bucket slide-hopper type trandsplanter was devised and tested. Test results of picking and transferring accuracies of the developed transplanter are as follows : A prototype transplanter performed with 1.5% of missing rate. The deviations of horizontal feed ranged from -0.3mm to 2.8mm and averaged 0.673mm for the 128-hoe test tray : and ranged from -lmm to ＋3mm and averaged 0.785mm for the 200-hole test tray. The deviations could decrease with precise manufacturing and lightening the mechanism. The maximum and deviations of vertical feed were -2.3mm and + 1mm, respectively, for the 128-hole test tray ; and were ＋3mm and ＋2.5mm, respectively, for the 200-hole test tray. The missing rate, seeding bruise rate and seed-bed damage rate were esitmate to be 1.3％, 0.4% and 3.5％, respectively, with the developed automatic transplanter.

• 한국농업기계학회:학술대회논문집
• /
• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
• /
• pp.979-983
• /
• 1993

A power operated (0.5 hp electric motor) grain flour separator was designed and developed for separation of grain (wheat, corn, chickpea and soybean) flour it no various fractions based on the size of the particles of the product. The separator is made of mild steel and consists of a hopper, power driven agitating mechanism, feed control , cylindrical separator unit and an eccentric mechanism. The machine was tested for wheat (variety : Subjata) flour separation into four fraction, viz : semolina ; Gr-I and II, flour (coarse) and white (fine) flour. Wheat samples (6.8% m.c., db) were first pearled by CIAE pearler for 15.8% bran removal . The product and machine characteristics were determined at different capacities varying from 24 kg/h to 143 kg/h. It was found that 76 kg/h capacity gave reasonably best results in terms of purity and recovery of semolina vis-a-vis the market product. The energy requirement of the machine at no-load was found to be 230 w and at load conditio s, it varied between 36.3-6.4kj per kg of feed separation. The machine could be used by small flour millers, small/medium size traders and retailers and other processors for making available various flour products of different particle size in the market for ready use fo the consumers.

• 대한기계학회논문집A
• /
• 제30권12호
• /
• pp.1634-1641
• /
• 2006

High-precision centerless grinding machines are emerging as a means of finishing the outer diameter grinding process required for ferrules, which are widely used as fiber optic connectors. In this study, a sensitivity analysis for structural and thermal characteristics was carried out using a virtual prototype of a centerless grinding machine to realize systematic design technology and performance improvements required to manufacture ferrules. The prototype consisted of a concrete-filled bed, hydrostatic grinding wheel (GW) and regulating wheel (RW) spindle systems, a hydrostatic RW table feed mechanism, a RW swivel mechanism, and on-machine GW and RW dressers. The results of the structural sensitivity analysis illustrated that the vertical stiffness of hydrostatic guideway for the RW table feed system greatly influenced the horizontal loop stiffness, and the results of the thermal sensitivity analysis illustrated that the heat generation rates at hydrostatic bearings and belt pulley greatly influenced the temperature rise of hydrostatic bearings and the deviation of thermal displacement between GW and RW.

• 한국산학기술학회논문지
• /
• 제12권11호
• /
• pp.4738-4744
• /
• 2011

본 연구는 상부에 설치되는 콘크리트 구조물 없이 설치되어 작동하는 새로운 소형 수문 시스템을 제안하였다. 주요 메커니즘은 유압시스템, 수문 상하 이송 메커니즘, 수문 잠금 제어장치, 이물질이 감지되면 수문이 파손되지 않도록 하는 안전장치 등으로 구성하였다. 유압 펌프 및 제어 시스템은 수문 시스템의 위치에서 떨어진 장소에 설치하여 상부 구조물을 제거할 수 있도록 하여 제어 하였다. 수문 인양 장치는 유압 액추에이터가 달린 래크와 피니언이 측면에 설치되어 작동되며 그 결과 제품의 원가 절감, 작동시 안전성 확보 및 제품의 컴팩트화를 구현하였다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제19권5호
• /
• pp.727-733
• /
• 2006

This experiment was conducted to investigate the effect of arsenic ($As^{III}$) on lipid peroxidation, glutathione content and antioxidant enzymes in growing pigs. Ninety-six Duroc-Landrace-Yorkshire crossbred growing pigs (48 barrows and 48 gilts, respectively) were randomly assigned to four groups and each group was randomly assigned to three pens (four barrows and four gilts). The four groups received the same corn-soybean basal diet which was supplemented with 0, 10, 20, 30 mg/kg As respectively. Arsenic was added to the diet in the form of $As_2O_3$. The experiment lasted for seventy-eight days after a seven-day adaptation period. Malondialdehyde (MDA) levels, glutathione (GSH) contents and superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST) activities were analyzed in serum, livers and kidneys of pigs. The results showed that pigs treated with 30 mg As/kg diet had a decreased average daily gain (ADG) (p<0.05) and an increased feed/gain ratio (F/G) (p<0.05) compared to the controls. The levels of MDA significantly increased (p<0.05), and the contents of GSH and the activities of SOD, CAT, GPx, GR and GST significantly decreased (p<0.05) in the pigs fed 30 mg As/kg diet. The results indicated that the mechanism of arsenic-induced oxidative stress in growing pigs involved lipid peroxidation, depletion of glutathione and decreased activities of some enzymes, such as SOD, CAT, GPx, GR and GST, which are associated with free radical metabolism.

• Asian-Australasian Journal of Animal Sciences
• /
• 제18권4호
• /
• pp.552-556
• /
• 2005

Malondialdehyde (MDA) and total antioxidant capacity (T-AOC) levels, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), glutathione transferase (GST) and xanthine oxidase (XOD) activities were analyzed in serum, livers and kidneys of pigs treated with graded doses of fluoride (as NaF). Ninety-six Duroc-Landrace-Yorkshire crossbred growing pigs (48 barrows and 48 gilts, respectively), with similar initial weight 24.14${\pm}$1.12kg, were randomly assigned to four different treatments. These treatments containing the following added F: basal control; 50 mg/kg F; 100 mg/kg F and 150 mg/kg F were randomly assigned to four pens (three barrows and three gilts) each in a completely randomized design. The results showed pigs treated with 150 mg/kg F significantly decreased average daily gain (ADG) (p<0.05) and increased feed/gain ratio (F/G) (p<0.05) compared to the controls. In the groups treated with fluoride, the contents of MDA increased, T-AOC levels and the activities of SOD, GSH-PX, CAT, GST and XOD decreased, and most of which altered significantly (p<0.05). The study therefore indicated the mechanism of excess fluoride on the impairment of soft tissues involved in lipid peroxidation and decreased the activities of some enzymes associated with free radical metabolism.

• 한국소음진동공학회논문집
• /
• 제23권5호
• /
• pp.385-393
• /
• 2013

In this paper, the mechanism identification and the avoidance measures on the phenomena of transient acoustic vibration amplified at the water-supply piping system to regulate the steam temperature of the boiler reheater in 500MW class supercritical power plant are presented. The pressure pulsation waves induced by the impeller passing of two feed-water pumps with five blades are coincident with the local acoustic modes of boiler reheater water-supply piping system. There are the phenomena amplified at the peaks of 5X, 10X, 15X and 20X in spectrums of piping vibration, sound pressure, and the feed-water's pressure pulsation waves. The shut-off device is installed in the piping system for the interception of pressure pulsation waves transmitted from two feed-water pumps and the modified design change of the piping layout is applied for the acoustic resonance avoidance. The acoustic natural frequencies are separated from the harmonics of pressure pulsation waves induced by the pump impellers passing through the design change of the span length. The acoustic vibration is gone by resonance avoidance measures. As a result, more than 20 dBA reduction is achieved from 100 dBA to 80 dBA.

• Journal of Advanced Marine Engineering and Technology
• /
• 제20권3호
• /
• pp.286-286
• /
• 1996

A neural predictive tracking system for the control of structure-unknown dynamic system is presented. The control system comprises a neural network modelling mechanism for the the forward and inverse dynamics of a plant to be controlled, a feedforward controller, feedback controller, and an error prediction mechanism. The feedforward controller, a neural network model of the inverse dynamics, generates feedforward control signal to the plant. The feedback control signal is produced by the error prediction mechanism. The error predictor adopts the neural network models of the forward and inverse dynamics. Simulation results are presented to demonstrate the applicability of the proposed scheme to predictive tracking control problems.