• 한국초지조사료학회지
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• 제38권1호
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• pp.30-38
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• 2018

본 연구는 산지초지에서 목초 파종량이 초지의 연차별 식생 및 생산성에 미치는 영향을 구명하고 산지초지 조성에 적합한 파종량을 설정하고자 2015년 8월부터 2017년 10월까지 평창군의 서울대학교 국제농업기술대학원과 천안시의 국립축산과학원 축산자원개발부 2개소에서 수행되었다. 처리는 총 4처리로 T1: 기준 파종량 대비 50%감량, T2: 기준 파종량(평창 $37kg\;ha^{-1}$, 천안 $34kg\;ha^{-1}$), T3: 기준 파종량 대비 50% 증량, T4: 기준 파종량 대비 100%증량 이었다. 월동 후 생육조사에서 T1이 목초 63%, 잡초 24%, 나지 13%로 가장 불량하였으며 T3와 T4는 목초 90%이상으로 매우 우수한 식생을 보였다. 분얼은 T1이 6.53개 (본/주)로 가장 높게 나타났고 T4가 4.49개(본/주)로 가장 낮게 나타났다. 정착 개체수는 T4가 62개($30{\times}30cm$)개로 가장 높게 나타났으며 T1이 44 ($30{\times}30cm$)개로 가장 낮게 나타났다. 정착률은 T1에서 92%로 가장 높았고 T4에서 79%로 가장 낮게 나타났다. 목초 식생은 2016에서 T2, T3, T4에서 목초 비율이 87~100%로 우수한 식생을 보였고 T1의 경우 목초 비율이 75~92%정도로 나타났다. 2017년도 목초 식생은 T1의 경우 1차 예취시기에서는 목초비율이 91% 였지만 4차 예취시기에서 75%까지 떨어졌다. 2017년 T2, T3, T4에서 목초의 비율은 79~95%의 양호한 식생을 유지하였다. 초장의 경우 유의적상관관계가 나타나지 않았다. 2016년 목초 건물 생산성은 T4 ($13,576kg\;ha^{-1}$)와 T3($12,727kg\;ha^{-1}$)가 가장 높았고 상대적으로 T1 ($9,583kg\;ha^{-1}$)과 T2 ($10,925kg\;ha^{-1}$)에서 낮게 나타났다(p<0.05). 2017년 전체 건물 생산성을 보면 T3 ($9,598kg\;ha^{-1}$)와 T4 ($9,294kg\;ha^{-1}$)가 가장 높았고 상대적으로 T1 ($6,809kg\;ha^{-1}$)과 T2 ($8,117kg\;ha^{-1}$)에서 낮게 나타났다(p<0.05). 2016년과 2017년 전체건물수량을 종합해보면 T4 ($11,435kg\;ha^{-1}$)와 T3 ($11,162kg\;ha^{-1}$)가 상대적으로 T1 ($8,196kg\;ha^{-1}$)과 T2 ($9,521kg\;ha^{-1}$)보다 높게 나타났다(p<0.05). 이상의 결과를 종합해 볼 때 겉뿌림 산지초지 조성시 기준량 대비 50%에서 100%증량은 목초의 정착률 및 생산성을 높이는 효과가 있었다.

• 한국양식학회지
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• 제9권3호
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• pp.215-222
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• 1996

감성돔, A. schlegeli 자치어의 성장 및 생존에 미치는 3,5,3'-triiodo-L-thyronine($T_3$) 경구투여 효과를 파악하기 위해 $T_3$를 0, 10, 20, 50 및 100 ppm으로 사료에 섞어 경구 투여하였다. $T_3$ 경구투여에 따른 사료섭식률은 10 ppm구와 20 ppm구에서 대조구와 큰 차이가 없었지만, $T_3$ 투여량이 증가할수록 감소하는 경향을 나타내었다. 그러나 사료효율의 경우 10 ppm구가 다른 실험구들에 비해 높았으나, 큰 차는 없었다. 생존율의 경우 100 ppm구가 대조구에 비해 높게 나타났으나, 그 외 처리구는 대조구와 차이를 보이지 않았다. 전장과 체중의 성장은 10 ppm 구가 다른 실험구보다도 높았고, 20 ppm구는 대조구와 거의 같은 수준에 있었으나, 50 ppm과 100 ppm구는 오히려 대조구보다도 느린 성장 경향을 나타내었다. 비만도는 대조구에서 가장 높은 수치를 보였으며, 10 ppm구를 비롯한 모든 $T_3$ 처리구가 대조구에 비해 유의하게 낮게 나타나, $T_3$ 투여량이 많아짐에 따라 비만도가 낮아지는 경향을 나타내었다.

• Journal of Ecology and Environment
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• 제34권3호
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• pp.279-286
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• 2011

The effect of allelochemicals on growth, root nodule nitrogen fixation activity, and ion patterns of soybeans were investigated. We prepared 50 g/L (T50), 100 g/L (T100), and 200 g/L (T200) extract concentrations by soaking fresh red pine needles in a nutrient solution. Adding needles to the nutrient solution increased the content of total phenolic acids, osmolality, and total ions. The total phenolic content in the T50, T100, and T200 extracts were $206{\pm}12.61$, $335{\pm}24.16$, and $603{\pm}12.30$ mg gallic acid equivalents, respectively. The $K^+$, $Mg^{2+}$, $Ca^{2+}$, and $PO_4^{3-}$ content increased by adding needles to the nutrient solutions, whereas $SO_4^{2-}$ content decreased. The growth inhibition of soybeans was proportional to the needle extract concentrations, and the T100 and T200 concentrations resulted in remarkable growth inhibition. On day 20 after treatment, dry weight and nitrogen fixation activity of the root nodules were reduced by the T100 and T200 treatments, whereas the T50 treatment was not difference from the control. After day 10, total ion content in all treatment groups was not different in comparison with the control. However, total ionic content in all treatment groups decreased significantly compared with that in the control after day 20. The lowest total ion value was found for the T200 concentration. The T200 treatment also resulted in significantly reduced $SO_4^{2-}$ content. The amounts of $Mg^{2+}$, $Ca^{2+}$, and $Mn^{2+}$ were higher than those of the control for the T50 treatment on day 10 and for T100 on day 20 after treatment. A significant increase in osmolality was observed in the T200 treatment on day 10 and in the T100 treatment on day 20. These results suggest that under severe allelochemical stress conditions, a remarkable reduction in nodule formation, nitrogen fixation activity, and ion uptake eventually resulted in a decrease in leaf production. Furthermore, increased $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Mn^{2+}$, and osmolality in soybeans exposed to lower concentrations of allelochemicals than the critical stress level helped overcome the stress.

• 한국항공우주학회지
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• 제35권10호
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• pp.948-956
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• 2007

항공기를 개발함에 있어 기체를 구성하는 계통의 성능이 항공기 요구도를 만족하는 수준으로 발휘되는지 확인하는 것이 중요하다. 특히, 엔진을 포함한 추진계통은 항공기를 구성하는 구성품 중 중요한 계통으로서, 추진계통과 기체와의 통합성을 검증하는 것이 항공기 개발에 있어 필수적 요소이다. T-50 고등훈련기 체계개발 시 추진계통 검증을 위해 엔진 공중재시동 시험 및 엔진 축마력 시험, backup throttle기능 시험 등의 다양한 비행시험을 수행하였으며, 이와 같은 항목의 비행시험을 통하여 T-50 고등 훈련기의 추진계통이 기체에 적합하게 설계/장착되었음을 확인하였다. 본 논문에서 추진계통 비행시험 항목에 대한 설명 및 시험 절차, 결과를 제시하였으며, 본 논문의 내용이 차후 타 항공기 개발 시 추진계통 관련 비행시험을 준비하는 과정에서 참고가 될 수 있을 것으로 기대한다.

• 한국정밀공학회지
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• 제29권3호
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• pp.307-312
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• 2012

This study aims to investigate the effect of the post weld treatments on the fatigue life of T-type welded structure made by a SM50A steel material, generally used for excavators, because changes in the geometry, material and surface properties of welded regions affect the fatigue life of welded structures. T-type test specimens were prepared by the CO2 welding of rolled steel plates (SM50A steel) with a thickness of 10 mm at a welding speed of 30 cm/min and these Ttype welded specimens were further treated by UIT (Ultrasonic Impact Treatment) and/or toegrinding post welding treatment methods. In order to investigate improvements on the fatigue life of the samples. 3-point bending fatigue tests were conducted with a stress ratio of R=0.1 under a cyclic loading environment at a frequency of 5 Hz, via a hydraulic fatigue testing machine (${\pm}100\;kN$, MTS 809). The tests were performed at room temperature. The fatigue life of UIT specimens was approximately 25 times longer than that of as-welded specimens at a stress amplitude of 281 MPa, while toe-grinding specimens exhibited 4.15 times longer fatigue life. The current results could provide important guidelines to determine the proper post weld treatment methodologies of T-type welded parts for excavators with a satisfactory fatigue life although under severe operating conditions.

• 한국항공우주학회지
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• 제34권7호
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• pp.105-111
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• 2006

항공기 엔진은 항공기가 각종 기동을 수행하도록 추력을 발생하는 것 외에 기동 수행을 위해 작동되는 조종면에 공급될 유압계통의 동력과 각종 항전장비 작동을 위한 전기계통의 동력을 공급한다. 엔진으로부터 제공되는 동력은 엔진의 고압압축기로부터 추출되기 때문에 축마력(Horsepower Extraction, HPX)이라하며, 추출되어 제공되는 엔진 축마력이 유압계통과 전기계통에서 요구하는 요구 축마력보다 작게 되면 엔진에 과도한 부하가 걸려 엔진회전수 감소(Rollback) 및 심한 경우 실속(stall)등이 발생할 수 있다. T/A-50체계개발 동안 요구 축마력과 엔진의 공급 축마력에 대한 비교 해석을 수행하였고, 해석 결과 엔진 축마력이 요구 축마력보다 작은 것을 확인하였다. 엔진 축마력 증가를 위한 엔진 제어 스케쥴 변경이 수행되었으며, 변경된 제어 스케쥴이 장착된 엔진을 이용하여 T/A-50비행시험을 수행하였다. 비행시험 결과를 통해 해석 결과 및 변경된 제어 스케쥴의 타당성을 검증하였다.

• 생명과학회지
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• 제18권11호
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• pp.1538-1542
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• 2008

본 연구는 와인숙성이 우육포의 품질특성에 미치는 영향을 규명하기 위하여 제조과정에 물 50 ml를 첨가한 육포(T0), 물 25 ml와 와인 25 ml를 첨가한 육포 그리고 와인 50 ml를 첨가 한 육포 등 세 종류의 육포를 제조하였다. 수분, 조단백질, 조지방 및 조회분 함량은 시료들 사이에 유의한 차이가 없었다. 육포의 명도($L^*$), 적색도($a^*$) 및 황색도($b^*$)는 시료들 사이에 유의한 차이가 없었다. 기계적 물성으로 측정한 경도, 탄성, 응집성, 뭉침성 및 씹힘성은 와인숙성이 영향을 미치지 않았다. 수분활성도, pH 및 TBARS값은 시료들 사이에 유의성이 없었지만 VBN함량과 총 균수는 T2가 가장 낮았다(p<0.05). 기호도 조사에서 풍미는 T2가 T0보다 유의하게 우수하였으나 (p<0.05) 맛, 색깔, 연도, 다즙성 및 전체적인 기호성은 시료들 사이에 유의한 차이가 없었다.

• Toxicological Research
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• 제13권1_2호
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• pp.87-94
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• 1997

This study was carried out to investigate toxicity of insecticide carbofuran and compensatory effects of phenobarbital sodium (PB) in vivo and in vitro. Sprague Dawley male rats were used as experimental animals and divided into carbofuran only administered group and simultaneous application group of carbofuran and PB. At 30 rain and 1, 3, 6, 12, 24, 48 and 96 hrs after each treatment, the animals were sacrificed by decapitation. Kidney were immediately removed, immersed in fixatives, and processed with routine method for light microscopic study. Paraffin sections were stained with H-E, PAM and PAS. $5.0\times 10^4$ cell/ml of NIH 3T3 fibroblast in each well of 24 multidish were cultured: After 24 hours, the cells were treated with solution of six groups; control group cultured in media only, carbofuran $MTT_50$ or $NR_50$ group cultured in the media containing carbofuran $MTT_50$ or $NR_50$ and four experimental groups cultured in the media containing carbofuran $NR_50$ plus various concentratins of PB. After the NIH 3T3 fibroblast of all groups were cultured in same condition for 48 hours, Tetrazolium MTT (MTT) and NR (neutral red) assay were performed to evaluate the cytotoxicity of cell organelles. Under the light microscope, atrophic change of renal corpuscles were frequently observed in 1 and 2 days after carbofuran treatment. The increase of the mesangium was apparent in 1 and 2 days after carbofuran treatment. Necrotic changes of the epithelium and loss of brush border of proximal tubules were most severe at 2 and 3 days after carbofuran treatment, respectively. In contrast, there were no evidences of the toxic effects on renal tissues at 48hrs in carbofuran-PB treated groups. Carbofuran $MTT_50$ and $NR_50$ were 78$\mu M$, 82.5$\mu M$ respectively. MTT and NR quantities were significantly increased in carbofuran-PB 100$\mu M$ treatment group and carbofuran-PB 100$\mu M$ treatment group. On the basis of these results, it is obvious that PB has compensatory effects against carbofuran toxicity.

• Asian-Australasian Journal of Animal Sciences
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• 제25권12호
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• pp.1721-1725
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• 2012

A growth and digestibility study was conducted using Osmanabadi goat male kids by feeding complete diets in the form of mash or expander extruded pellets containing different levels of red gram (Cajanus cajan) straw (RGS). Two iso-nitrogenous complete diets were prepared by incorporating RGS at 35% and 50% levels. Half the quantity of each complete mash feed was then converted into pellets through expander extruder processing. Thirty two kids of 4 to 5 months age were divided into four groups of eight each and were fed for 150 d with four experimental diets (T1: mash with 35% RGS, T2: mash with 50% RGS, T3: pellets with 35% RGS and T4: pellets with 50% RGS). Pelleting of complete diets significantly (p<0.001) increased the voluntary feed intake (671.45 vs 426.28 g/d) at both levels of RGS in the feeds. Average daily gain (ADG, g/d) also increased significantly (p<0.001) from 48.79 in kids fed mash diet to 71.29 in those fed with pelleted diets. Feed conversion efficiency (dry matter (DM) intake: weight gain) was comparable among all the treatment groups. Digestibility of nutrients was not affected by pelleting of the feeds whereas, increasing the level of inclusion of RGS in feeds from 35% to 50% decreased (p<0.05) the digestibility of DM and crude protein (CP) resulting in lower (p<0.001) metabolizable energy (ME) content (MJ/kg DM) in feeds with 50% RGS (7.93 vs 8.75). Daily intake (MJ/kg $BW^{-0.75}$) of ME decreased (p<0.05) in feeds containing 50% RGS while pelleting of feeds increased (p<0.05) the intake of DM, CP, digestible crude protein (DCP) and ME. It is inferred that expander extruder pelleting can efficiently utilize RGS up to 50% level in complete diets for growing goat kids.

• Clinical and Experimental Reproductive Medicine
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• 제25권2호
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• pp.207-216
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• 1998

Certain types of somatic cells, as well as follicular cumulus cells associating with mammalian oocytes, are known to produce beneficial effects on in vitro fertilization and pre implantation development of mammalian eggs when they are present in oocyte culture medium. To investigate the nature of the effects of somatic cells, the resistance of mouse oocytes against chymotrypsin treatment was examined after culture within various cell conditioned media. When mouse oocytes matured for 17-18 hr in the presence of cumulus cells were treated with 1 % chymotrypsin, half of them remained still alive even after 240 min $(t_{50}>240.0)$. In contrast half of mouse oocytes cultured without cumulus cells underwent degeneration within 65.0 min $(t_{50}=65.0{\pm}13.2min)$ of the same treatment. To see if the effects were duc to the secretory products of cumulus cells, mouse cumulus cells were cultured for 20 hr in medium containing 0.4% BSA and the supernatant of culture medium (conditioned medium) was taken. After maturation in the cumulus cell conditioned medium, mouse oocytes exhibited $t_{50}=190.0{\pm}10.8$ min upon chymotrypsin treatment whereas half of oocytes cultured without conditioned medium degenerated within 25.5 min. Human granulosa cell conditioned medium gave similar effects such that oocytes matured in conditioned medium exhibited $t_{50}=183.3{\pm}19.1$ min while $t_50$ of control group oocytes was $60.0{\pm}6.8$ min, Oocytes matured in vero cell conditioned medium exhibited $t_{50}=196.7{\pm}8.8$ min. On the other hand, amniotic cell conditioned medium resulted in the chymotrypsin resistance of $t_{50}=80.0{\pm}8.4$ min which was not statistically different from the control value of $t_{50}=48.0{\pm}13.2$ min. Based upon these results, it is suggested that certain somatic cell types including cumulus cells might change the biochemical properties of mouse oocyte membrane during meiotic maturation as revealed by the enhanced resistance against chymotrypsin treatment. Such effects of somatic cells appear to be mediated via the secretory products rather than direct communication between somatic cells and oocytes.