• 대한치과의사협회지
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• 제47권7호
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• pp.435-443
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• 2009

The purpose of this study was to compare the centering ratio and reduction of canal curvature according to the preparation sizes of #30, #40 and #50 using three rotary NiTi instruments which have different shaft tapers. Seventy-two simulated root canals in clear resin blocks (Endo Training Bloc; Dentsply Maillefer, Ballaigues, Switzerland) were divided as following 3 groups according to the file system; the 24 canal blocks prepared with each of ProTaper Universal system (Group P), LightSpeed eXtra system (Group L), and K3 (Group K). The pre- and post-instrumented root canals were scanned and superimposed to evaluate and calculate the centering ratio and reduction of canal curvature. Mean scores of each group were statistically analyzed using one-way ANOV A and Duncan's multiple range test for post-hoc comparison. The results were as followings: 1. Group L showed better centering ratio, followed by K and P. And all experimental groups generally showed increasing tendency of centering ratio as the apical size was increasing from #30 to #50, except at 1 mm level of group P where showed reducing tendency of centering ratio. The smaller the ratio, the better the instrument remained centered in the canal. 2. Group P showed more decrease of canal curvature at all apical shaping size (p < 0.05). Under the conditions of this study, the shaft design could affect the quality of canal shaping and the smooth taperless flexible (LightSpeed) shaft design was capable of preparing canals with good morphological characteristics in curved canals.

• Composites Research
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• 제31권6호
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• pp.429-434
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• 2018

본 연구에서는 구조물에 부착된 분포형 광섬유 센서의 변형률을 정밀하게 분석하기 위해 위치에 따른 변형률의 변화를 고려하여 광섬유 센서의 변형률 전달률을 분석하였다. 표면에 부착된 코팅된 광섬유 센서의 모델로부터 해석적으로 광섬유 센서의 변형률 전달률을 유도하였으며, 유도된 변형률 전달률은 유한요소해석을 통해 수치적으로 해석한 결과와 비교 검증하였다. 주 구조물의 변형률이 동일한 파장을 가지며 변하는 경우 센서의 변형률 전달률은 위치에 따라 동일한 값을 보였으며, 따라서 변형률 분포의 형상은 왜곡되지 않는다. 하지만 위치에 따라 변형률 파장이 변하면 변형률의 전달률이 위치에 따라 달라져 변형률 분포의 형상이 왜곡될 수 있음을 확인하였다. 본 연구를 통해 얻어진 파장에 따른 변형률 전달률은 분포형 광섬유 센서로부터 주 구조물의 변형률 분포를 정밀하게 추정하는데 유용하게 사용될 것으로 기대된다.

• Structural Engineering and Mechanics
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• 제53권5호
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• pp.1051-1066
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• 2015

The study aims on the effect of material dependency in elastic- plastic contact models by contact analysis of sphere and flat contact model and wheel rail contact model by considering the material properties without friction. The various materials are selected for the analysis based on Young's modulus and yield strength ratio (E/Y). The simulation software 'ANSYS' is employed for this study. The sphere and flat contact model is considered as a flattening model, the stress and strain for different materials are estimated. The simulation of wheel-rail contact model is also performed and the results are compared with the flattening model. The comparative study has also been extended for finding out the mean contact pressure for different materials the E/Y values between 150 and 660. The results show that the elastic-plastic contact analysis for materials up to E/Y=296.6 is depend on the nature of material properties and also for this material the mean contact pressure to yield strength reaches 2.65.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.341-344
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• 2003

This paper proposes a tree-winding transformer protective relaying algorithm based on the ratio of increment of flux linkages (RIFL). The RIFL of the two windings is equal to the turns ratio for all operating conditions except an internal faults. For a single-phase transformer and three-phase transformer containing the wye-connected windings, the increments of flux linkages are calculated. for a three-phase transformer containing the delta-connected windings, the difference of the increments of flux linkages between the two phases are calculated using the line currents, because the winding currents are practically unavailable. Their ratios are compared with the turns ratio. The results of various tests show that the algorithm successfully discriminates internal faults from normal operation conditions such as magnetic inrush, overexcitation and external faults. The algorithm can not only detect internal winding faults, but reduce the operating time of a relay.

• 한국식품영양과학회지
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• 제19권4호
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• pp.279-284
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• 1990

This experiment was conducted to study the effect of dietary vitamin E on the lipid composi-tion of rats treated with carbon tetrachloride. Rats were divided into five groups I. e. C(soybean oil with vitamin E(40mg/kg diet)) EF(CCl4 with vitamin E deficient diet) 40E(CCl4 with vitamin E(40mg/kg diet) 400E(CCl4 with vitamin E(400mg/kg diet) 800E(CCl4 with vitamin E(800mg/kg diet) Body weight gain and food efficient ratio were not observed significant differences. The liver weight was significantly increased in the CCl4 treated groups but the liver weight of 800E group was significantly lower than that of EF group. In EF and 40E groups kidney weights were significantly higher compared to that of C group. The content of total lipid in liver of 40E and 400E groups were significantly higher than that of control group but in 400E and 800E groups the contents were significantly lower compared with that of EF group. The content of triglyceride in liver was significantly higher in the CCl4 treated group and the content of cholesterol was significantly higher in the EF and 40E groups but those of 800E group were significantly lower compared with those of EF group. In CCl4 administration groups were significantly higher than those of control group and 400E and 800E groups were significantly lower than those of EF group.

• 한국수산과학회지
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• 제29권4호
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• pp.464-473
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• 1996

쥐노래미의 단백질 요구량을 조사하기 위해 카제인과 북양어분을 단백질원으로 하여, 사료의 단백질 함량이 30, 40, 50, $60\%$가 되도록 조정한 4종의 실험사료와 사료의 적정 에너지 함량을 조사하기 위해 가용에너지/단백질 (EP) 비가 9, 10, 11, 12인 4종의 실험 사료를 각각 설계하여 사육실험을 실시하였다. 29g 전후의 쥐노래미를 2개월간 사료의 단백질 함량별로 2반복으로 사육 실험한 결과, 증체율 및 사료효율은 모두 단백질 $50\%$ 사료에서 가장 좋았고, 단백질 $60\%$ 사료에서 성장효과는 오히려 감소하여 4개 실험구 중에서 가장 낮은 값을 나타내었다 (P<0.05). 수학적인 방법으로 이차회귀곡선상에서 증체율을 지표로 하여 단백질요구량을 추정한 결과 최대 단백질 요구량이 $45\%$로 나타났다. 일일사료섭취율은 실험구간에 서로 차이가 없었으나, 단백질섭취율은 사료의 단백질 함량이 증가됨에 따라 증가하는 경향을 보였으며, 단백질효율은 사료 단백질 함량이 증가될수록 유의하게 감소하였다(P<0.05). 가장 성장이 좋았던 실험구의 일일단백질섭취율이 어체중 100g 당 1.7g 이였으며, 이차회귀곡선상에서는 일일단백질 요구량이 어체중 100g당 1.5g으로 나타났다. 전어체의 수분함량은 사료 단백질 함량 $40\~60\%$구간에서는 차이가 없었으나, 사료 단백질 $30\%$구는 $40\%$구보다 유의하게 낮은 값을 보였다(P<0.05). 단백질과 회분 함량은 실험구간에 차이가 없었으며, 지질 함량은 단백질 $30\%$ 실험구가 가장 높았고, $40\%$ 실험구가 가장 낮았다(P<0.05) E/P 비가 다른 사료로 사육 실험한 결과, 증체율, 사료효율 및 단백질효율이 E/P 비가 12인 실험구가 다른 실험구보다 높은 값을 보였다. 전어체의 수분, 단백질 및 회분 함량은 사료의 에너지 함량에 영향을 받지 않았으나, 지질 함량은 에너지가 높은 사료인 E/P 비 11과 12 사료에서 유의적으로 높은 값을 보였다. 본 실험 결과로부터 평균체중 100g 이하의 성장기 쥐노래미의 단백질 요구량은 $45\~50\%$, 일일단백질 요구량은 어체중 100g 당 $1.5\~1.7g$으로 추정되며, 쥐노래미 사료의 적정 E/P 비는 12 전후가 적당할 것으로 생각된다.

• 국제초고층학회논문집
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• 제1권1호
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• pp.1-13
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• 2012

The importance of appropriate use of damping evaluation techniques and points to note for accurate evaluation of damping are first discussed. Then, the variation of damping ratio with amplitude is discussed, especially in the amplitude range relevant to wind-resistant design of buildings, i.e. within the elastic limit. The general belief is that damping increases with amplitude, but it is emphasized that there is no evidence of increasing damping ratio in the very high amplitude range within the elastic limit of main frames, unless there is damage to secondary members or architectural finishings. The damping ratio rather decreases with amplitude from a certain tip drift ratio defined as "critical tip drift ratio," after all friction surfaces between primary/structural and secondary/non-structural members have been mobilized.

• 한국환경보건학회지
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• 제26권4호
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• pp.129-133
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• 2000

The objective of this study was to invetigate the coagulation effects of landfill leachate by using Acid Mine Drainage(AND). The coagulation efficiency was investigated by mixing landfill leachate with F $e^{+3}$ solution earned by oxidation of pyrite(AMD). In the results of this experiment, it was found that the amount of removed COD and SS was approximately 30% respectively by mixing at the ratio of AMD three to leachate one. And it showed highest turbidity removal efficiency at all mixing ratio. Concentration of Fe was decreased with increasing mixing ratio, however it was increased inversely at mixing ratio 4. Optimal mixing ratio was 3 at the results obtained by leachate coagulation experiments. Also removal efficiency at mixing ratio 3 corresponded to 500mg/$\ell$ of FeC $l_3$ dosage. it was suggested that pretreatment by mixing of AMD and leachate remove both suspended organic material of leachate and metal of AMD.

• 대한한의학회지
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• 제24권3호
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• pp.1-10
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• 2003

Background : Asthma is a chronic inflammatory disorder under immunological influence. Gamichunggumgangwha-tang (CG, Jiaweiqingjinjianghuo-tang) and Gamiyukmigiwhang-tang (YM, Jiaweiliuweidihuang-tang) are herbal tonics for asthma from traditional herbal medicine. Objective : To evaluate the effect of CG and YM on immune cell & serum OA-specific IgE in broncho-alveolar lavage fluid (BALF) in a rat asthma model. Materials and Methods : Rats were sensitized with OA; at day I sensitized group and CG and YM groups were systemically immunized by subcutaneous injection of 1mg OA and 300mg of Al(OH)3 in a total volume of 2ml. At the same time, 1 ml of 0.9% saline containing $6{\times}10^9$ B. pertussis bacilli was injected by Lp. 14 days after the systemic immunization, rats received local immunization by inhaling 0.9% saline aerosol containing 2% (wt/vol) OA. A day after local immunization, BALF was collected from the rats. Rats were orally administered with each of CG and YM extract for 14 days since the day after local immunization. Lymphocyte, CD4＋ T cell and CD8＋ T cell counts, CD4＋/CD8＋ ratio in BALF, change of serum OA-specific IgE level, CD4＋ T cell and CD8＋ T cell percentages in the peripheral blood were measured and evaluated. Results : CG and YM showed an alleviating effect on asthmatic responses of rats. CG decreased total cell, lymphocyte, CD4＋ T cells in BALF, and serum OA-specific IgE level as compared with the control group. YM decreased lymphocytes as compared with the control group. CD4＋/CD8＋ ratio in BALF from the CG and YM groups and serum OA-specific IgE level from the YM group didn't show any significant variation from the control group. Conclusion : CG alleviated asthmatic hyperreactivity of the immune system through CD4＋ T cells and serum IgE. Further the study of this immune system modulating mechanism is expected.

• 천문학회보
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• 제17권
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• pp.16.3-17
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• 1992