• Asian-Australasian Journal of Animal Sciences
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• 제6권4호
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• pp.601-605
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• 1993

This study was purposed to investigate the efficiency of protein utilization of rapeseed meal (RSM) and formaldehyde-treated RSM (TRSM) by sheep, and their influence on performance of growing heifers. Experiment 1 was conducted according to a double $3{\times}3$ Latin square design involving sex yearling Hu Sheep and three experimental diets. All diets contained 600 g ammoniated rice straw and 200 g concentrate mixture. Three dietary treatments were: (1) 100 g RSM + 40 g soybean meal (URUS), (2) 100 g TRSM + 40 g soybean meal (TRUS) and (3) 100 g TRSM + 40 g treated soybean meal (TRTS). Apparent nitrogen digestibility was significantly higher for diet TRUS than that for URUS or TRTS (p<0.05), but with no significant difference between URUS and TRTS (p>0.05). Proportion of nitrogen retention (NR) to the digestible nitrogen intake for diet TRUS and TRTS was 25.57 (p<0.05) and 23.44% (p<0.05) higher than that for URUS respectively. As a result, proportion of NR to nitrogen intake for diet TRUS and TRTS was 34.74 (p<0.05) and 23.78% (p<0.05) higher than that for URUS respectively. Experiment 2 was conducted with 59 Holstein heifers. They were 12-20 months of age at the start of the trial. The experiment was a $2{\times}2$ factorial trial in which the heifers were given the ammoniated rice straw ad libitum and 1.5 kg hay, and supplemented with either RSM or TRSM at a daily allowance of 1.2 or 1.8 kg per day. The live weight gains for heifers receiving 1.2 and 1.8 kg/d of RSM or TRSM were 0.491 and 0.556 or 0.564 and 0.665 kg/d, respectively. The results suggest that formaldehyde treatment can effectively improve the efficiency of protein utilization of rapessed meal and cattle's performance.

• Asian-Australasian Journal of Animal Sciences
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• 제28권8호
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• pp.1116-1122
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• 2015

This study aimed to investigate the effect of sunflower seeds, either as whole or as oil, on rumen fermentation, milk production, milk composition and fatty acids profile in dairy goats. Fifteen lactating Damascus goats were divided randomly into three groups (n = 5) fed a basal diet of concentrate feed mixture and fresh Trifolium alexandrinum at 50:50 on dry matter basis (Control) in addition to 50 g/head/d sunflower seeds whole (SS) or 20 mL/head/d sunflower seeds oil (SO) in a complete randomized design. Milk was sampled every two weeks during 90 days of experimental period for chemical analysis and rumen was sampled at 30, 60, and 90 days of the experiment for ruminal pH, volatile fatty acids (tVFA), and ammonia-N determination. Addition of SO decreased (p = 0.017) ruminal pH, whereas SO and SS increased tVFA (p<0.001) and acetate (p = 0.034) concentrations. Serum glucose increased (p = 0.013) in SO and SS goats vs Control. The SO and SS treated goats had improved milk yield (p = 0.007) and milk fat content (p = 0.002). Moreover, SO increased milk lactose content (p = 0.048) and feed efficiency (p = 0.046) compared to Control. Both of SS and SO increased (p<0.05) milk unsaturated fatty acids content specially conjugated linolenic acid (CLA) vs Control. Addition of SS and SO increased (p = 0. 021) C18:3N3 fatty acid compared to Control diet. Data suggested that addition of either SS or SO to lactating goats ration had beneficial effects on milk yield and milk composition with enhancing milk content of healthy fatty acids (CLA and omega 3), without detrimental effects on animal performance.

• 한국항공우주학회지
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• 제32권4호
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• pp.61-66
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• 2004

본 논문은 액체 로켓 엔진 연소기에 사용하는 분사기의 연소 안정성 평가를 위한 모델 시험 방법을 서술하고자 한다. 액체 로켓 엔진 연소실에서 발생하는 연소 조건을 모사하기 위해서 로켓 엔진 연소기에 적용되는 실물 크기 분사기를 이용하여, 기체상태의 산소와 메탄과 프로판의 혼합기체를 모의 추진제로 사용한 모델 연소 시험을 수행하였다. 본 모델 시험의 주요 가정은 추진제의 혼합 과정이 실제 엔진 연소기에서 발생하는 연소 불안정에 가장 큰 영향을 미치는 인자로 간주하는 것이다. 본 시험에서는 단일 F-OO-F 형태의 충돌형 분사기가 한쪽 끝이 열린 원통형 모델 연소기와 더불어 사용되었다. 기상 연소 조건에서 발생하는 동압 특성은 운전 조건에 따라 상대적인 음향 감쇠 특성을 보인다. 이러한 시험 결과를 통해 구해질 수 있는 운전 조건에 따른 음향 감쇠 특성 지도를 이용하여 여러 후보 분사기 중에 가장 안정적인 분사기를 선택할 수 있게 된다.

• Nutritional Sciences
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• 제7권3호
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• pp.151-157
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• 2004

The aim of this study was to investigate the effects of chicory fructan fiber supplementation on bone mineral density, apparent absorption of minerals and serum parameters related to bone turnover in postmenopausal women. Twenty-six healthy Korean postmenopausal women participated in the study. 1be participants were randomly divided into two groups in a double-blind parallel design and took one of the supplements for 3 months; either a placebo of 8g maltodextrins/sucrose mixture (control group) or 8g chicory fructan fiber (fructan group). During the 3-month experimental period no differences were found in bone mineral density (BMD) between the two groups. Apparent calcium absorption significantly increased by 42% in the fructan group, while that of the control group decreased by 29% as compared to the values at baseline. Urinary calcium excretion was not significantly different between the group;;. After 3 months, the level of serum alkaline phosphatase (ALP) was significantly lower in the fructan group than in the control group and deoxypyridinolin showed a trend toward a slight reduction. In conclusion, intake of chicory fructan fiber with a regular increases apparent calcium absorption in postmenopausal women.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.629-632
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• 2008

콘크리트는 온도에 따른 품질변동이 큰 재료로서, 타설 후 소요의 품질을 확보하기 위해 계절특성파악 및 콘크리트 주위의 온 습도를 적절한 범위로 유지시켜 유해한 작용을 받지 않도록 주의해야 한다. 특히 하절기의 경우 높은 대기온도의 영향으로 초기재령에서 시멘트의 급속한 수화반응으로 유발하여 시멘트경화체 내부가 자기건조상태가 되어 결과적으로 자기수축에 의한 콘크리트의 강도저하를 발생시킬 수 있다. 그러므로 단위수량 및 단위시멘트량의 최소화 및 혼화재 사용 등 서중콘크리트의 수화열 저감을 통한 강도저하방지대책이 필요하다. 따라서 본 연구에서는 배합 및 양생온도조건이 콘크리트의 압축강도에 미치는 영향을 확인하고자 혼화재 치환율 변화, 콘크리트의 초기양생온도변화 및 양생조건변화에 따른 압축강도 특성을 비교 검토하였다.

• Journal of Forest and Environmental Science
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• 제31권2호
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• pp.119-125
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• 2015

This study examined the effects of rice straw steaming time and mixing ratio between rice straw and wood particle on the properties of mixed particle board from Acacia mangium Willd wood and rice straw. Rice straw and Acacia mangium Willd wood were collected in Hanoi, Vietnam. The particle board was three-layer particle board with the structural ratio of 1:3:1. The thickness, density and board size of the particle board were 18 mm, $0.7g/cm^3$, and $800{\times}800{\times}18$ (mm, including trimming), respectively. A resin mixture between commercial Urea-formaldehyde (U-F) adhesive and methylene diphenyl isocyanate (MDI) adhesive was used with a dosage of 12% for the core layer and 14% for the surface layer. In this experimental design, the steaming time for rice straw was 15, 30, 45, 60, and 75 minutes at $100^{\circ}C$. The rice straw-wood mixing ratio was 10, 20, 30, 40, and 50%. The results showed that both mixing ratio and steaming time affect the properties of the particleboard, but the mixing ratio has a stronger impact. A higher mixing ratio and a longer steaming time resulted in a better quality of particleboard. The optimal steaming time for rice straw was 46.12 minutes with the straw-wood mixing ratio of 29.85% with the following characteristics of the particle board: the modulus of rupture (MOR) of 14.64 MPa, internal bond strength (IB) of 0.382 MPa, thickness swelling (TS) of 8.83%, and board density of $0.7-0.7g/cm^3$.

• 한국건설순환자원학회논문집
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• 제5권4호
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• pp.414-420
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• 2017

이 연구에서는 고온의 태양열 에너지를 저장하기 위한 고로슬래그 콘크리트의 열역학적 특성을 파악하였다. 고로슬래그 콘크리트의 열역학적 특성에 미치는 영향을 파악하기 위한 실험연구를 수행하였다. 실험변수로써 고로슬래그 함유량과 물-바인더 비를 고려하였다. 고로슬래그 콘크리트의 역학적 특성으로써 열사이클 전과 후의 압축강도 및 인장강도를 측정하고, 열적 특성으로써 열전도율과 비열을 측정하였다. 고로슬래그를 포함한 콘크리트의 열싸이클 적용 후의 잔류압축강도가 고로슬래그를 포함하지 않은 콘크리트의 잔류압축강도보다 크다. 또한, 고로슬래그를 혼입한 콘크리트의 열전도율이 고로슬래그를 포함하지 않은 콘크리트의 열전도율보다 더욱 크다. 이는 고로슬래그 콘크리트가 열에너지의 축열과 방열에 효과적인 것을 나타낸다. 실험연구 결과는 콘크리트 열저장 축열 모듈 설계에 효율적으로 활용될 수 있다.

• 한국화재소방학회논문지
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• 제24권6호
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• pp.139-144
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• 2010

기계포소화약제는 다량의 물에 포소화약제 원액을 녹인 포수용액을 발포기에 의하여 기계적인 수단으로 공기와 혼합 교반하여 거품을 발생시키는 약제를 말한다. 다양한 설비(이동식, 고정자동식) 적용성, 대형의 유류화재 적합, 대량.연속 생산이 가능한 약제의 특수성 및 장기보관이 가능한 특징이 있어 이에 대한 개발 및 연구가 꾸준히 진행되고 있다. 그러나 이러한 포소화약제는 주변의 온도 및 운용조건에 따라 발포력의 변화가 큰 특징이 있어 실제 겨울철 소방 활동시에는 사용을 자제하고 있다. 본 연구에서는 소화활동시 온도가 발포력에 미치는 영향을 분석하고 이를 활용하여 소방차에 적용 가능한 시스템을 개발하였다. 결과로 기준 약제 혼합비인 3.0%일 경우 온도차에 따라 최대 30.08%의 발포성능차가 발생하는 것으로 분석되었다. 또한 자동 혼합 시스템의 적용성을 분석한 결과 설계값과 실제실험값의 오차가 최대 0.012%로 나타남에 따라 해당 시스템의 적용성이 확보된 것으로 판단되었다.

• 대한기계학회논문집B
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• 제25권2호
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• pp.180-186
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• 2001

The condensation heat transfer coefficients of pure refrigerants R-22, R-134a, and a binary refrigerant mixture R-410A flowing in a small diameter tube were investigated. The experiment apparatus consists of a refrigerant loop and a water loop. The main components of the refrigerant loop consist of a variable-speed pump, a mass flowmeter, an evaporator, and a condenser(test section). The water loop consists of a variable-speed pump, an isothermal tank, and a flowmeter. The condenser is a counterflow heat exchanger with refrigerant flowing in the inner tube and water flowing in the annulus. The test section consists of smooth, horizontal copper tube of 3.38mm outer diameter and 1.77mm inner diameter. The length of test section is 1220mm. The refrigerant mass fluxes varied from 450 to 1050kg/(㎡$.$s) and the average inlet and outlet qualities were 0.05 and 0.95, respectively. The main results were summarized as follows ; in the case of single-phase flow, the heat transfer coefficients increase with increasing mass flux. The heat transfer coefficient of R-410A was higher than that of R-22 and R-134a, and the heat transfer for small diameter tubes were about 20% to 27% higher than those predicted by Gnielinski. In the case of two-phase flow, the heat transfer coefficients also increase with increasing mass flux and quality. The condensation heat transfer coefficient of R-410A was slightly higher than that of R-22 and R-134a. Most of correlations proposed in the large diameter tube showed significant deviations with experimental data except for the ranges of low quality and low mass flux.

• 대한기계학회논문집A
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• 제24권9호
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• pp.2159-2166
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• 2000

Recently, high performance machining center requires special type of sealing mechanism that prevent a leakage of oil jet or oil mist lubrication system. Sealing of oil-air mixture plays important r oles to have an enhanced lubrication for performance machining center. Current work emphasizes on investigations of the air jet effect on the protective collar type labyrinth seal. To improve sealing capabilities of conventional labyrinth seals, air jet is injected against the leakage flow. In this study, an adapted model is introduced to improve sealing capability of conventional non-contact type seals. It has a combined geometry of a protective collar type and an air jet type. Both of a numerical analysis by CFD (Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement. The sealing effects of the leakage clearance and the air jet magnitude aic studied in various parameters. Gas or liquid has been used as a working fluid for most of nori-contact types seals including the labyrinth seal. However, it is more reasonable to regard two-phase flows because oil mist or oil jet are used for high performance spindle's lubrication. In this study, working fluid is regarded as two phases that are mixed flow of oil and air phase. Both of turbulence and compressible flow model are also introduced in a CFD analysis to represent an isentropic process. Estimation of non-leaking property is determined by amount of pressure drop in the leakage path. Results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient. Effect of the sealing improvement is explained as decreasing of leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger