• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.451-455
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• 2010

In this study, the various supply system of LRE such as a feed-line, an elbow, and an orifice as a part of integrated analyzing has been combined to develop the performance analysis program. Computational analysis has been used to compare the results and to verify the validity and limitation conditions of the performance analysis program by changing orifice positions.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.1
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• pp.35-44
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• 2011

Mathematical modelling for liquid rocket engine(LRE) main components were conducted to predict the dynamic characteristics when the LRE operates at the transient condition, which include engine start up, shut down, or thrust control. Propellant feeding system is composed of fuel and oxidizer feeding components except for regenerative cooling channel for the fuel circuit. Components modeling of pump, pipe, orifice, control valve, regenerative cooling channel and injector was serially made. Hydraulic tests of scale down component were made in order to validate modelling components. The mathematical models of engine components were integrated into LRE transient simulation program in concomitant with experimental validation.

• Asian Journal of Turfgrass Science
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• v.25 no.1
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• pp.94-99
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• 2011

This study was performed to investigate the effect of foliar feeding as the fertilization on creeping benrgrass green. Research results have showed that the visual quality of bentgrass as well as shoot density and chlorophyll index dramatically improved after foliar feeding. Shoot density of bent grass in foliar based fertilization was 2.8 ea/$cm^2$ higher than that of the liquid based fertilization during the experiment period, moreover that the foliar feeding is more effective to alleviate shoot density during the rainy season in summer. Results showed that foliar feeding was key role to achieve the stable visual quality, chlorophyll index and maintained Normalized Difference Vegetation Index (NDVI) throughout the year in addition to get fast recovery after aeration and dry spot. These were consistent with the previous research of foliar feeding which directly provided nutrient to the turfgrass leaf thus increased turfgrass growth within a short time. It is projected to be a especially adequate management program during the hot summer season in which the nutrition feeding is low. However, root growth was no significant difference between foliar based fertilization and liquid based fertilization. Golf Course managers also should consider about the number of frequent fertilizing. Lastly, it was no big change in chemical property by soil foliar based fertilization which is meaning of preventing the soil salinization, meanwhile, it is prone to reach the nutrient deficiency. It hopes to be settled as the general fertilization in golf course of Korea, since there are many advantages of foliar based fertilization program. It is suggested to study more practical process of foliar feeding through the further research.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.9-17
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• 2007

The performance test of recirculation line in propellant feeding system was carried out. Liquid oxygen was used as cryogenic propellant and helium was used as recirculation promotion gas. Tests were done in cases at atmospheric pressure and at pressure of 4 barg in the ullage space of propellant tank. Liquid oxygen recirculation flowrate with helium injection flowrate and temperature distribution along the line were measured. There was appropriate helium injection flowrate for gas-lift recirculation system. Test data were used to make calculation program by test data correlation method. In this paper the procedure of calculation was presented and the results were compared to test data.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.10
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• pp.1617-1623
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• 2020

Objective: This study was conducted to investigate the effects of dietary probiotic blend and liquid feed program at different nutritional densities on growth performance, nutrient digestibility, fecal score of weaning piglets. Methods: A total of 120 weaning pigs with an initial body weight of 7.05±0.93 kg per pig (21 days of age) were randomly allocated into 1 of the following 8 dietary treatments (3 replicates per treatment with 5 pigs per replicate) in a 2×2×2 factorial arrangement (nutrition levels: apparent metabolic energy [AME] = 3,500 kcal/kg, crude protein [CP] = 20% vs AME = 3,400 kcal/kg, CP = 19.42%; feed types:dry vs wet; probiotics levels: 0 mg/kg vs 300 mg/kg). Results: During d 5 to d 15, greater average daily gain (ADG) and average daily feed intake (ADFI) (p<0.05) were observed in probiotics treatments. During d 15 to d 25, gain:feed (G:F) ratio (p<0.05) were significantly improved in probiotics, wet feed and high nutrition diet. Moreover, two interactions i) between nutrition levels and feed types, and ii) between nutrition levels and probiotics were found in G:F ratio. Furthermore, there was a significant positive interaction on G:F among those 3 factors (p<0.05). Overall, increasing ADG, ADFI, and G:F ratio were detected in probiotics treatment significantly (p<0.05). Besides, an obvious reduction on fecal score was observed in probiotics treatment from d 0 to d 5 (p<0.05). There was an interactive effect on fecal score between feed types and nutrition concentrations from d 5 to d 25 (p<0.05). Conclusion: These results indicated that probiotics supplementation could benefit growth performance and reduce the frequency of watery feces. Besides, wet feed program (feed:water = 1:1.25) could improve the G:F. The effect of liquid feed or probiotic could be influenced by dietary nutrition density in weaned piglets. An increased value of G:F was obtained when wet feeding a high nutrition diet (100 kcal higher than NRC 2012 recommendations) was supplemented with probiotics for 15 to 25 days.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.181-189
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• 2010

개방형 액체로켓엔진 시스템에 대한 동특성 예측 프로그램을 작성하였다. 이 프로그램을 통해 얻은 펌프 시동 시 시간에 따른 압력 및 유량 변화 결과를 수류실험장치를 구축하여 실험적으로 검증하였다. 수류실험장치는 실제 액체로켓엔진 추진제 공급 계통에서 구성품의 형태와 배치위치, 가스발생기와 주연소실로 분기되는 유량비를 기준으로 모사되었다. 측정 시 관로가 채워진 상태에서 펌프를 시동하였으며 펌프는 전동기로 구동된다. 동특성 예측 프로그램의 작성을 위해 구성품별 동특성 모델링을 수행하고 엔진 시스템을 기준으로 각 모델링을 순차적으로 통합하였다. 구성품의 동특성 파라미터를 측정 반영하였고 압력 밸런싱을 통해 수렴 조건이 결정된다. 수렴된 밀도와 유량을 가지고 다음 시간에서의 초기 입력 값으로 대체하여 계산을 수행하였다. 천이 작동 상태에서 엔진 시스템 내의 물리량 변화를 전산 예측과 더불어 실험적으로 측정하고 비교하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.3
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• pp.66-73
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• 2005

The pressurization system in a liquid rocket propulsion system provides a controlled gas pressure in the ullage space of the vehicle propellant tanks. It is advantage to employ a hot gas heat exchanger in the pressurization system to increase the specific volume of the pressurant and thereby reduce over-all system weight. A significant improvement in pressurization-system performance can be achieved, particularly in a cryogenic system, where the gas supply is stored inside the cryogenic propellant tank. In this study liquid nitrogen was used instead of liquid oxygen as a simulant. The temperature characteristic of cryogenic pressurant is very important to develop some components in pressurization system. Numerical modeling and test data were studied using SINDA/FLUINT Program and PTF(Propellant-feeding Test facility).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.168-175
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• 2005

The pressurization system in a liquid rocket propulsion system provides a controlled gas pressure in the ullage space of the vehicle propellant tanks. It is advantage to employ a hot gas heat exchanger in the pressurization system to increase the specific volume of the pressurant and thereby reduce over-all system weight. A significant improvement in pressurization-system performance can be achieved, particularly in a cryogenic system, where the gas supply is stored inside the cryogenic propellant tank. The temperature characteristic of cryogenic pressurant is very important to develop some components in pressurization system. Numerical modeling and Test data were studied using SINDA/FLUINT Program and PTF(Propellant-feeding Test Facility).

• Fisheries and Aquatic Sciences
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• v.18 no.2
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• pp.165-171
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• 2015

Abalone containing phlorotannins is produced by feeding the phlorotannin-rich brown seaweed Eisenia bicyclis after 4 days of starvation. Reverse-phase high-performance liquid chromatography (RP-HPLC) was used to isolate and quantify phlorotannins, which were identified by mass spectrometry and [$^1H$]-nuclear magnetic resonance to be the P1 compound, 7-phloroeckol, and eckol. When E. bicyclis was used as feed, P1 compound accumulated to an average of 1.60 mg/g dry weight of abalone muscle tissue after 18 d, 7-phloroeckolol to 0.21 mg/g after 16 d, and eckol to 0.22 mg/g after 12 d. Saccharina japonica was used as a control feed, and the abalone showed little or no accumulation of phlorotannins in muscle tissue. Feed consumption and growth rate were very similar when either E. bicyclis or S. japonica was fed for 20 d. Half-maximal reductions in the levels of P1 compound, 7-phloroeckol, and eckol accumulation were attained in 1.5, 1.9, and 3.4 days, respectively, after the feed was switched from E. bicyclis to S. japonica. Value-added abalone containing bioactive phlorotannins can be produced by simply changing the feed to the phlorotannin-rich E. bicyclis 18 d prior to harvesting.

• Journal of Korea Foundry Society
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• v.11 no.1
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• pp.44-53
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• 1991

The proper feeding conditions for thin Al-Alloy (AA336, JIS AC8A) castings in permanent mold were investigated to eliminate microshrinkage porosity. 5mm-thick plates (200mm long, 60mm wide) were cast with increasing padding taper from 0 to 5% under different conditions : (1) constant mold temperature of $350^{\circ}C$, (2) continuous production with uniform mold thickness (10mm), (3) continuous production with a negative taper of 2.5% in mold thickness (thickness decreasing in direction to riser). The test casting were machined off to the midplane and the shrinkage porosity was examined visually. The critical padding taper which can just eliminate the shrinkage porosity was determined for each condition, i.e. : (1) 4.5% at the constant mold temperature, (2) 3.5% for continuous production with the uniform mold thickness (3) 1.5% for continuous production with the taper in mold thickness. A computer simulation by a finite difference analysis program was applied to the test casting. The liquid fraction gradient (LFG) and the temperature gradient divided by the square root of the cooling rate (G /SR) were calculated at the end of solidification and compared with the shrinkage porosity area in the castings. For the case of constant mold temperature, LFG is a better parameter to predict shrinkage porosity than G /SR and its critical value is around 11%/cm. But for the case of continuous production, neither LFG nor G /SR could be a reliable parameter. The experimental results about the critical padding taper are of practical interest for designing permanent molds and castings. The computer simulation results stimulate further research to be directed on the prediction of centerline microshrinkage porosity in continuous production.