• Journal of Microbiology and Biotechnology
• /
• 제25권2호
• /
• pp.185-195
• /
• 2015

Glucoamylase is an important industrial enzyme. Glucoamylase production by industrial Aspergillus niger strain featured with two major problems: (i) empirical substrate feeding methods deteriorating the fermentation performance; and (ii) the high raw materials cost limiting the economics of the glucoamylase product with delegated specification. In this study, we first proposed a novel three-stage varied-rate substrate feeding strategy for efficient glucoamylase production in a 5 L bioreactor using the standard feeding medium, by comparing the changing patterns of the important physiological parameters such as DO, OUR, RQ, etc., when using different substrate feeding strategies. With this strategy, the glucoamylase activity and productivity reached higher levels of 11,000 U/ml and 84.6 U/ml/h, respectively. The performance enhancement in this case was beneficial from the following results: DO and OUR could be controlled at the higher levels (30%, 43.83 mmol/l/h), while RQ was maintained at a stable/lower level of 0.60 simultaneously throughout the fed-batch phase. Based on this three-stage varied-rate substrate feeding strategy, we further evaluated the economics of using alternative carbon sources, attempting to reduce the raw materials cost. The results revealed that cornstarch hydrolysate could be considered as the best carbon source to replace the standard and expensive feeding medium. In this case, the production cost of the glucoamylase with delegated specification (5,000 U/ml) could be saved by more than 61% while the product quality be ensured simultaneously. The proposed strategy showed application potential in improving the economics of industrial glucoamylase production.

• 소성∙가공
• /
• 제14권9호통권81호
• /
• pp.764-771
• /
• 2005

This study is related with the development of CNC spinning machine and the axisymmetric conventional spinning such as drum type and conical type steel shells. The CNC spinning machine is constructed with heavy duty frame and the hydraulic servo system is applied in order to give the exactness of motion control. The experiment has been carried out considering feeding velocity, mandrel shape, and the corner radius of mandrel and forming rollers. As a result of experiment, the limiting spinning ratio and thickness strain distribution are obtained and it can be seen that the spinnability is dominant to the feeding velocity and corner radius of forming roller. This research can contribute to the development of axisymmetric mechanical part which is applicable to automotive and aerospace industry.

• 한국분무공학회지
• /
• 제14권2호
• /
• pp.65-70
• /
• 2009

An experimental study was performed to explore the atomization characteristics as the drop formation and the liquid breakup of an ethanol fuel using an electrohydrodynamic atomizer. A developed electrohydrodynamic atomizer controlled by a high AC power, a variable frequency, and a liquid feeding was used for the experiments. The test had been considered a disperse atomization processing at $450{\sim}4200V$ applied power, $200{\sim}400\;Hz$ frequency, and $1{\sim}3\;ml/min$ ethanol feeding to achieve an uniformed droplet formation. The goal of the research was to investigate the possibility of the liquid breakup for an ethanol fuel in an electrohydrodynamic atomizer. The results showed that the mean droplet radius decreased as the applied voltage increased or as the applied AC frequency increased. The whipping motion had been grown at the specified voltages due to the applied frequency.

• Journal of Ecology and Environment
• /
• 제46권4호
• /
• pp.304-315
• /
• 2022

Background: Filter-feeding zooplankton has limited food resources owing to their habitat. Consequently, it is crucial for them to acquire all essential compounds, such as fatty acids (FAs) and amino acids, from confined diets. To elucidate the trophic transfer of FAs to filter feeders, the primary consumers in freshwater ecosystems, we compared the FA accumulation patterns of two species of filter-feeding zooplankton, Daphnia magna and Branchinella kugenumaensis, in a laboratory experiment. Experimental neonates and nauplii preyed on a single phytoplankton species (Selenastrum capricornutum) for three days after hatching prior to diet switching. Five replicates per feeding group in each species were fed on six different types of mixed phytoplankton diet for 10 days after diet switching. Subsequently, the consumers and diets were harvested and FAs were extracted. Results: Principal component analysis showed that the FA profiles of zooplankton were well-grouped by species and diet. Although diet affects the FA profiles of consumers, they exhibit different FA accumulation patterns. D. magna had a higher 18C-ω3 content and ω3/ω6 ratio than did B. kugenumaensis. In contrast, B. kugenumaensis had higher contents of 18:1ω7 and 20:5ω3 (eicosapentaenoic acid), 22:6ω3 (docosahexaenoic acid), and a higher ratio of ∑18C monounsaturated FAs to ∑18C-ω3 polyunsaturated FAs than did D. magna. Conclusions: This study showed that two primary consumers, D. magna and B. kugenumaensis, fed the same diet had different assimilation patterns of FAs under controlled environments. Specific FA accumulation patterns in filter feeders can provide information on the transfer process of various FAs to high-trophic organisms.

• 한국연소학회지
• /
• 제4권2호
• /
• pp.43-50
• /
• 1999

Liquefied petroleum gas (LPG) has been used as motor fuel due to its low emissions and low cost. The fuel feeding system has been improved with stringent requirement for exhaust emissions. LPG carburetion system was first introduced, then the system has been changed to a precisely controlled gas injection system, but this gas feeding system has a limitation on improving power output. In order to improve an engine performance, a multi-point port injection system was introduced recently, and a liquid direct injection system into a cylinder was suggested as a next generation system to maximize a fuel economy as well as a power. This study addresses the analysis of the LPG spray from diesel injectors. The spray images are visualized and compared with diesel sprays in a wide injection pressure range. The photographs show much wider dispersion of LPG sprays.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
• /
• pp.21-26
• /
• 1999

Liquefied petroleum gas(LPG) has been used as motor fuel due to its low emissions and low cost. The fuel feeding system has been improved with stringent requirement for exhaust emissions. LPG carburation system was firstly introduced, then the system changed into a gas injection system controlled precisely, but those gas feeding system has a limitation on improving power output. In order to improve an engine performance, a multi-point port injection system was introduced recently, and a liquid direct injection system into a cylinder was suggested as a next generation system to maximize a fuel economy as well as a power. This study addresses the analysis of the LPG spray from diesel injectors. The spray images are visualized and compared with diesel sprays in a wide injection pressure range. The photographs show much wider dispersion of LPG sprays.

• 한국식품조리과학회지
• /
• 제9권2호
• /
• pp.109-115
• /
• 1993

This study was attempted to investigate the current status of industry food service management in Chonbuk province. The survey for the analysis was conducted through the questionaires to dietitian. The following results are to be noted. 1. Only one dietitian was employed regardless of feeding numbers and feeding times, and the average number of cooks comes to 5∼6 persons. Among 51 food service places for the study, 84.3% provided more than two meals a day. Feeding number were 200∼1000 people per one meal (64.7%) and feeding cost amounts to 700∼1000 won per meal per one person. 2. The food preferences and budget were primary considerations in menu planning. The type of menus was a non-selective menu with a seven-day cycle (83.7%). Most of dietitian (94.1%) had control of food purchasing, receiving and checking procedure and prefered placing orders by phone (94.5%) through the purveyors (86.4%). 3. In many food service places (70.5%), the mass food preparation was controlled of cooking method and standardized recipes were not undertaken by management Also, the food quality control such as flavor, texture, appearance and temperature was not fully established in food service system. 4. They used the method of manual dish washing operations (88%) and about 71.4% of them are dependent on boiling method of ultrabiolet light for disinfection of kitchen utensils. 5. The performance rates of dietitian management responsibility showed as nutritional management 100%, working management 72.4%, sanitary management 85.6%, personnel management 64.5% and nutrition education 40.7%, but they did not perform the objective and systematic their own responsibility as specialized dietitian because only few dietitian used basic check list and management tools. In addition, dietitian (21.6%) worked beyond their field. In the result, only 54.9% dietitian have satisfied their own occupation and most of them emphasized on practical working in educational curriculums.

• Clinical Psychopharmacology and Neuroscience
• /
• 제16권4호
• /
• pp.481-488
• /
• 2018

Preliminary studies have claimed that short term fasting would negatively affect school performance and cognition. In contrast some other studies have reported not important decline in cognition and executive function as a result of fasting. Also limited attention was generally devoted to dietetic regimens, nutritional status and body weight. Yet neuroscience and neuro-cognitive aspects of acute hunger on the electroencephalogram and differences between obese and non-obese cases is not well understood. Hence, we decided to design and perform a case study in a more controlled situation similar to reality. Therefore, we performed several examinations including subjective tests (for eating status) and objective tests (cognitive tests such as Stroop effect and Sternberg search and electroencephalogram measures such as steady-state visual evoked potential and auditory steady-state responses) for an obese and a non-obese academic case before and after a simple breakfast. The results showed that the breakfast effects on the neuro-cognitive functions depend on either obesity status, nutritional status of the case or the type of cognitive task (visual or auditory). This paper would open a new insight to answer some important questions about the neuro-cognitive implications of fasting and feeding in obese and non-obese human cases.

• 한국산학기술학회논문지
• /
• 제21권5호
• /
• pp.672-678
• /
• 2020

교류전기철도 급전시스템에 병렬급전방식을 적용할 경우, 전동차 부하로 인한 전압강하 및 최대순시부하를 감소시켜 급전구간을 연장하고 급전용량을 향상시킬 수 있다는 장점이 있다. 그러나 변전소 간에 위상차가 있을 경우 순환전력이 발생하기 때문에 적용이 제한되며, 전동차 운행에 따른 부하 분포에 따라 변전소 부하 불균형이 커져서 급전용량이 저하되는 문제점이 있다. 본 논문에서는 변전소 위상차 및 전동차 부하분포에 따라 변동하는 순환전력을 실시간 제어하고 변전소 부하 불균형을 해소하기 위하여 사이리스터 제어 위상조정장치 (TCPAR: Thyristor Controlled Phase Angle Regulator, 이하 TCPAR)를 적용하는 방식을 제안하고, 이를 구현하기 위한 검토를 수행하였다. 전기철도 급전 시스템에 TCPAR을 적용하기 위한 제어 기법으로서, 변전소 공급전력을 입력으로 이용하여 변전소 위상차 및 전동차 부하 분포에 따라 변동하는 순환전력과 변전소 부하 불균형을 효과적으로 억제하는 제어모델을 제시하였다. PSCAD/EMTDC를 이용한 시뮬레이션 결과, 전기철도 병렬급전에 제안한 TCPAR을 적용함으로써 변전소 위상차 및 전동차 부하분포에 따라 변동하는 순환전력 및 변전소 부하 불균형을 효과적으로 억제시킬 수 있다는 것을 확인하였다. 제안 기법을 전기철도 병렬급전에 적용할 경우, 병렬급전 적용 범위를 확대하고 급전용량을 증가시킬 수 있을 것으로 기대된다.

• Nutrition Research and Practice
• /
• 제15권5호
• /
• pp.613-627
• /
• 2021

BACKGROUND/OBJECTIVES: Despite the widespread use of dietary assessment tools, the validity of food records has not been evaluated in Koreans. We assessed the accuracy of estimated food records and the effect of a short education session in young Korean women. SUBJECTS/METHODS: Thirty women (aged 18-23 yrs) each completed 3 food records during a controlled-feeding study. One educational session was provided on day 2 of the study. Food records were analyzed for the accuracy of food items and portion size estimation according to food group (grains; meat, fish, eggs, and beans; vegetables; fruit; dairy; and oils and sugars) and type of dish (rice, kimchi, soup, side dishes, spreads, beverages, and snacks). Reported food items were categorized as exact, close, or far matches, exclusions, or intrusions. Portion sizes were evaluated as accurate, similar, or inaccurate estimates, or missing. The means of days 2 and 3 were used to assess post-education results. Paired t-tests were performed to assess the effects of the education session. RESULTS: The mean percentages of exact matches, close matches, far matches, and exclusions on day 1 were 80.9%, 10.9%, 2.0%, and 6.2%, respectively, and mean intrusions observed were 0.1. The education session slightly increased the accuracy of recorded food items. The percentages of accurate, similar, and inaccurate estimates, and missing portion sizes were 11.7%, 19.8%, 12.2%, and 56.3%, respectively, at baseline. The percentage of missing portion size estimates decreased to 14.0% after the education session, resulting in an increase in the percentages of all other estimates. An increase was observed in the accuracy of reported portion sizes of vegetables, rice, and kimchi. CONCLUSIONS: In young Korean women, estimated food records are highly accurate for food items but not for portion size estimates without prior education. A short education session can improve the accuracy of portion size estimation.