• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.36-40
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• 2003

In order to discuss the availability of aerostatic guideways driven by the coreless linear motor to ultra precision machine tools, a prototype of guideway is designed and tested in this research. A coreless linear DC motor with the continuous force of 156N and a laser scale with the resolution of $0.01\mu\textrm{m}$ are used as the feeding system. The experiments are performed on the static stiffness, motion accuracy, positioning accuracy, microstep response and variation of velocity. The guideway also has $0.21\mu\textrm{m}$ of positioning error and $0.09\mu\textrm{m}$ of repeatability, and it shows the stable response against the $0.01\mu\textrm{m}$ resolution step command. The velocity variation of feeding system is less than 0.6%. From these results, it is confirmed that the aerostatic guideway driven by the coreless linear motion is very useful for the ultra precision machine tools.

• Journal of Ecology and Environment
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• 제37권4호
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• pp.225-229
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• 2014

Feeding behavior of Temora turbinata was investigated through laboratory experiments with special emphasis on its food preference and consequent clearance rate on diatom and microbial components given as common natural food assemblage of coastal area (Uchiumi, Uwa Sea, Japan). Among available prey items, T. turbinata showed the highest clearance rate for Thalassiosira spp. ($0.23{\pm}0.08L\;Temora^{-1}day^{-1}$) followed by Chaetoceros spp. ($0.11{\pm}0.03L\;Temora^{-1}day^{-1}$), but clearance rates for other diatom, Nitzschia spp. was lower (0.03 to $0.07L\;Temora^{-1}day^{-1}$). Bacterial abundances showed no response against 24-h feeding of T. turbinata. Feeding of T. turbinata on heterotrophic nanoflagellates (HNF) was apparent when clearance rates of T. turbinata on diatoms were relatively low, but T. turbinata did not consume HNF as well as ciliates with Thalassiosira spp. of which clearance rate was highest. The results suggest that HNF and ciliates are possible supplementary prey item for T. turbinata, but their contribution as food sources can be limited by the presence of other prey items such as preferable diatom species.

• Asian-Australasian Journal of Animal Sciences
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• 제7권4호
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• pp.493-498
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• 1994

The response of crossbred Holstein milking cows to the neutralized urea-treated rice straw feeding was investigated. Rice straw was treated with 6% urea for at least 21 days and further with sulfuric acid for overnight to complete the neutralization. The neutralized straw was then sun-dried and its feeding value was compared with that of the dried non-neutralized urea-treated straw. They were fed to the cows with concentrates either by the ration formulation based on the nutrient requirements for milk production recommended by NRC or by the traditional way in which straw was fed ad libitum and concentrates at 1 kg/2 kg of milk production. The results showed that milk production as well as milk composition of cows were not different between neutralized and non-neutralized straw. The feeding of the neutralized straw could significantly reduce the supply of protein-rich feed such as soybean oil meal, and it was demonstrated that ammonium sulfate in the neutralized straw could be utilized as effective as the plant origin protein. The results also suggested that if the traditional feeding method is applied to the dairy cattle, protein content of the supplementing concentrates should be increased to meet the requirement.

• 한국추진공학회지
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• 제6권3호
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• pp.45-52
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• 2002

본 연구에서는 액체 로켓의 축방향 불안정성에 대한 개요와 국내 최초의 액체 추진로켓인 과학로켓 3호 (KSR-III) 추진기관 공급계 시스템에 대한 주파수 특성에 대한 결과를 다룬다. 공급계에 설치된 여러 구성품 중 벨로우즈와 벤튜리의 cavitation volume이 공급계의 주파수 특성에 미치는 영향을 파악하였다. 벨로우즈는 공급계의 고유진동수를 낮추는 데 큰 역할을 함을 알 수 있다. 또한 KSR-III의 산화제와 연료 공급계의 고유진동수는 각각 약 280Hz와 90Hz임을 알 수 있다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권5호
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• pp.340-344
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• 2000

Microbial oxidation of D-sorbitol to L-sorbose by Acetobacter suboxydans is of commercial importance since it is the only biochemical process in vitamin C synthesis. The main bottleneck in the batch oxidation of sorbitol to sorbose is that the process is severely inhibited by sorbitol. Suitable fed-batch fermentation designs can eliminate the inherent substrate inhibition and improve sorbose productivity. Fed-batch sorbose fermentations were conducted by using two nutrient feeding strategies. For fed-batch fermentation with pulse feeding, highly concentrated sorbitor (600g/L) along with other nutrients were fed intermittently in four pulses of 0.5 liter in response to the increased DO signal. The fed-batch fermentation was over in 24h with a sorbose productivity of 13.40g/L/h and a final sorbose concentration of 320.48g/L. On the other hand, in fed-batch fermentation with multiple feeds, two pulse feeds of 0.5 liter nutrient medium containing 600g/L sorbitol was followed by the addition of 1.5 liter nutrient medium containing 600g/L sorbitol at a constant feed rate of 0.36L/h till the full working capacity of the reactor. The fermentation was completed in 24h with an enhanced sorbose productivity of 15.09g/L/h and a sorbose concentration of 332.60g/L. The sorbose concentration and productivity obtained by multiple feeding of nutrients was found to be higher than that obtained by pulse feeding and was therefore a better strategy for fed-batch sorbose fermentation.

• 대한영양사협회학술지
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• 제2권1호
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• pp.81-91
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• 1996

Customer satisfaction concerning foodservice quality characteristics were evaluated by using importance performance analysis(IPA) techniques in employee feeding operations. The purpose of this study were to survey employees' health condition and their food habits, to examine employees' perception of the importance and performance concerning foodservice quality charactertics and to analyze attributes for quality improvement in employee feeding operations. A questionaire for survey was developed and mailed to 1,700 employees and the response rate was 60.8%. Statistical data analysis was done using the SAS programs for descriptive analysis, $x^2$-test, F-test and Fisher's LSD. The results of this study were as follows 1. Most of employees responded that their health condition were generally good. 2. 17.8% of surveyed employees responded that they usually skipped their breakfast. 3. Main reasons of using employee feeding facilities identified were convenience and cheap price of meals. 4. Dissatisfied quality attributes identified were taste of food, atmosphere and location d dinning room, and the quality of food served for breakfast and dinner, 5. Satisfied quality attributes identified were nutritionally balanced meal with variety, competitive managerial skills of dietetian, and quality of food served for lunch.

• Asian-Australasian Journal of Animal Sciences
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• 제2권3호
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• pp.249-250
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• 1989

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.416-423
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• 2004

This paper presents the thermal characteristic analysis of a high-speed horizontal machining center with spindle speed of 50,000rpm and feedrate of 120m/fin. The spindle system is designed based on the built-in motor, angular contact ceramic ball bearings, oil-air lubrication and oil-jacket cooling method. The X-axis and Y-axis feeding systems are composed of the linear motors and linear motion guides, and the Z-axis feeding system is composed of the servo-motor, ball screw and linear motion guides. The thermal characteristics such as the temperature distribution, temperature rise, thermal deformation and step response, are estimated based on the finite element model of machining center and the heat generation rates of heat sources related to the machine operation conditions. Especially, the thermal time constant assessed from the step response function is introduced as an index of thermal response characteristics.

• 한국식품영양과학회지
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• 제33권1호
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• pp.225-228
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• 2004

반응표면분석법(RSM)을 활용하여 유동층과립기의 흡입공기온도, 물의 투입비율, 분무압력 등이 분유의 과립화에 미치는 영향을 분석하였다. 분유의 과립화 수율은 물의 투입 비율에 많은 영향을 받고 있음을 알 수 있었으며, 겉보기밀도 및 다짐 밀도는 분무압력에 크게 영향을 받고 있음을 보여주었다. 분유의 유동층 과립화의 최적조건은 흡입공기온도6$0^{\circ}C$, 물의 투입비율 16 mL/min, 그리고 분무압력 2.1 bar이었으며, 이때 과립화 수율은 94.0%, 겉보기밀도는 0.350 g/㎤, 그리고 다짐밀도는 0.446 g/㎤로 각각 예측되었다.

• 한국공작기계학회논문집
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• 제13권5호
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• pp.30-37
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• 2004

This paper presents the thermal characteristic analysis of a high-speed horizontal machining center with spindle speed of 50,000rpm and feedrate of 120m／min. The spindle system is designed based on the built-in motor, angular contact ceramic ball bearings, oil-air lubrication and oil-jacket cooling method. The X-axis and Y-axis feeding systems are composed of the linear motors and linear motion guides, and the Z-axis feeding system is composed of the servo-motor, ball screw and linear motion guides. The thermal characteristics such as the temperature distribution, temperature rise, thermal deformation and step response, are estimated based on the finite element model of machining center and the heat generation rates of heat sources related to the machine operation conditions. Especially, the thermal time constant assessed from the step response function is introduced as an index of thermal response characteristics.