• 한국정밀공학회지
• /
• 제26권11호
• /
• pp.99-107
• /
• 2009

Since a long work piece influences the natural frequency of the entire system with a miniature high speed spindle, a bar-feeder is used for a long work piece to improve the vibration characteristics of a spindle system. Therefore, it is very important to design optimally support positions between a bar-feeder and a long work piece for a miniature high speed spindle system. The goal of the current paper is to present an optimization method for the design of support positions between a bar-feeder and a long work piece. This optimization method is effectively composed of the method of design of experiment (DOE), the artificial neural network (ANN) and the genetic algorithm (GA). First, finite element models which include a high speed spindle, a long work piece and the support conditions of a bar-feeder were generated from the orthogonal array of the DOE method, and then the results of natural vibration analysis using FEM were provided for the learning inputs of the neural network. Finally, the design of bar-feeder support positions was optimized by the genetic algorithm method using the neural network approximations.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2008년도 추계학술대회 논문집
• /
• pp.461-462
• /
• 2008

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제13권1호
• /
• pp.31-44
• /
• 2013

Recently, due to the high rise of energy costs and environmental problem issues, much attention has been paid to wood pellets. Wood pellets are produced by compressing woody biomass into cylindrical form. Wood pellets are suitable for use at various scales in industrial furnaces for heat production to replace conventional fossil fuel energy sources since the use of wood pellet that is carbon neutral can alleviate global warming. This study presents the result of developing two industrial wood pellet boilers with high safety having capacities of 290kW and 440kW. Efficiency has been improved by using a rotating screw bar grate burner. Special attention has been paid to the improvement of the safety of the wood pellet boilers from backfire by adopting a triple protecting system composed of a rotary feeder, an air curtain, and a backfire protecting DC-fan.

• Animal Bioscience
• /
• 제35권12호
• /
• pp.1817-1826
• /
• 2022

Public concern on the methods of raising food-producing animals has increased, especially in the last two decades, leading to voluntary and mandated changes in the animal production methods. The primary objective of these changes is to improve the welfare of farm animals. The use of gestational stalls is currently a major welfare issue in swine production. Several studies assessed the welfare of alternative housing systems for gestating sows. A comparative study was performed with gestating sows housed in either individual stalls or in groups in a pen with an electronic sow feeder. This review assessed the welfare of each housing system using physiological, behavioral, and reproductive performance criteria. The current review identified clear advantages and disadvantages of each housing system. Individual stall housing allowed each sow to be given an individually tailored diet without competition, but the sows had behavioral restrictions and showed stereotypical behaviors (e.g., bar biting, nosing, palate grinding, etc.). Group-housed sows had increased opportunities to display such behavior (e.g., ability to move around and social interactions); however, a higher prevalence of aggressive behavior, especially first mixing in static group type, caused a negative impact on longevity (more body lesions, scratch and bite injuries, and lameness, especially in subordinate sows). Conclusively, a more segmented and diversified welfare assessment could be beneficial for a precise evaluation of each housing system for sows. Further efforts should be made to reduce aggression-driven injuries and design housing systems (feeding regimen, floor, bedding, etc.) to improve the welfare of group-housed sows.

• 한국진공학회지
• /
• 제16권6호
• /
• pp.483-488
• /
• 2007

KSTAR (Korea Superconducting Tokamak Advanced Research) 전류전송계 (Current Feeder System)는 4.5 K의 저온에서 운전되는 초전도자석과 300 K의 실온에서 운전되는 전원장치 (Magnet Power Supply)를 전기적으로 연결하는 장치이다. 전류전송계는 최대 35 kA의 DC 전류가 인가되는 TF 자석용 및 350초간 20$\sim$26 ㎄의펄스 전류가 인가되는 PF 자석용으로 분리되어 있으며 리드박스 내부는 전류인입선, 초전도버스라인, 열차폐체 및 냉각라인 등이 설치되어 있다. 리드박스와 초전도버스라인 진공덕트는 KSTAR 주장치와는 별도로 진공배기 시스템이 구축되어있으며, 전체적으로 아령 형상을 하고 있는 진공공간을 효율적으로 진공배기하기 위하여 버스라인 덕트와 주장치 저온용기 사이에 진공 분리막 (Vacuum Separator)이 설치되어 있다. 진공배기를 위한 초벌배기계는 로터리펌프 및 부스터펌프 (Mechanical Booster Pump)로 구축되었으며 고진공 배기계는 4대의 크라이오펌프 (Cryo-pump)로 구축되었다. 진공장치 운전을 위해 PLC 기반의 로컬 제어시스템을 구축하였고 장치 안전을 위한 자체 인터록과 중앙인터록 시스템 및 중앙제어연계시스템이 함께 구축되어 있다. 전류전송계 설치완료 후 진공배기 시운전을 통해 배기시스템의 자가진단 및 리드박스 내부에 설치되어 있는 헬륨배관의 진공누설검사를 완료하였으며, 액체질소를 사용하여 전류인입선 냉각시험을 완료하였다.