• 수산해양기술연구
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• 제28권2호
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• pp.191-196
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• 1992

This paper is an experimental study to investigate utility of ultrasonic treatment of fuel oil in diesel engine. Experiment was carrid out to clarify the effect of ultrsonic vibration on the characteristics of maximum pressure, fuel consumption ratio, smoke, BMEP and torque. The result obtained are as follows: 1. In the case of given ultrsonic vibration, the maximum pressure is increased in all experimental conditions. 2. In the case of given ultrsonic vibration, the decrease effect of fuel consumption rate is increased at low rpm. 3. The generation quantity of soots is increased according to load. In the case of given ultrsonic vibration, the decreased quantity of soots does not very according to load. 4. In the case of given ultrsonic vibration, the BMEP and torque are increased at low load.

• 대한치과보철학회지
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• 제46권4호
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• pp.381-395
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• 2008

서론: 임플랜트와 자연치가 혼재하는 증례에 있어서 보철물의 연결여부와 그 결과에 대해 논쟁이 많이 있어왔다. 본 연구에서는 임플랜트와 자연치를 이중관으로 연결했을 경우에 치조골 내에서 임플랜트 주변 조직의 하중에 대한 응력의 양상을 분석하여 자연 치와 임플랜트를 연결하는 보철물의 방식으로 이중관의 사용가능성을 비교 분석하고자 하였다. 연구재료 및 방법: 실험군으로서는 한 개의 자연치아와 한 개의 임플랜트를 이중관으로 연결한 모델을 사용하고, 대조군으로 두 개의 임플랜트를 이중관으로 연결한 모델을 사용하여 응력분포의 차이를 비교분석하였다. 임플랜트와 자연치 각각 통상적인 금합금을 사용하여 내,외관을 모델링한 후 각각의 외관을 연결한 구조를 형성한다. 내관과 외관은 $6^{\circ}$의 경사도 (taper)로 형성하고 내외관 사이의 공간을 인정하여, 하중을 가했을 경우 내외관 사이에 합금의 마찰력과 변위를 계산하여, 그 결과가 골내 임플랜트의 응력 분포에 영향을 줄 수 있도록 실험모델을 형성하였다. 하중은 일반적인 저작력의 크기로 임플랜트 부위와 자연치 부위에 각각 부여하여 응력의 차이를 비교하였으며, 최종적으로 대조군과의 차이를 비교하고자 하였다. 하중 조건은 임플랜트와 자연치아 사이, 임플랜트 후방, 전방부 자연치아의 사이에 하중을 가하였으며, Load case 1, 2, 3로 분류하였다. 실험을 위해서 ANSYS Version 8.1을 사용하여 3차원 유한 요소 분석을 시행하였다. 연구성적: 지대주에 가해지는 응력 - 최대 응력은 실험군이 대조군에 비해 각각 2.4 (Load Case1), 1.02 (Load Case2), 0.46 (Load Case3)배 높게 나타났으며,Load Case3의 경우 대조군의 최대응력이 더욱 높게 나타났는데, 이것은 전치부 치아의 경우 하중을 효과적으로 분산하기 때문인 것으로 보인다. 악골내에 가해지는 응력 - 악골내에서 최대 응력은 실험군이 대조군에 비해 각각 1.69 (Load Case1), 1.26 (Load Case2), 1.93 (Load Case3) 배 크게 나타났다 결론: 임플랜트와 자연치아가 혼재된 경우, 이중관으로 상부 보철물을 연결한 경우, 임플랜트만으로 구성된 대조군에 비해, 임플랜트 및 임플랜트 식립 부위의 악골에 가해지는 최대 응력은 1.02 에서 2.4배 가량 높게 나타났다. 자연치아의 움직임이 임플랜트의 경부 및 악골 내에 응력을 집중시킨 것으로 보이며, 자연치아가 있는 악골부위에서는 응력이 거의 발생하지 않았다. 본 실험의 경우 자연치아와 임플랜트에서 모든 하중을 받는 것으로 계산하였고, 실제 가철성 의치에서 나타나는 점막의 영향을 배제하였기 때문에, 실제 임상에서는 후방 임플랜트에 미치는 최대 응력의 크기는 2.4배 이하일 것으로 추정할 수 있다. 앞으로, 실제 임상에 적용하였을 경우, 임플랜트에 미치는 영향 및 자연치아에 미치는 결과에 대한 연구가 필요할 것이다.

• Journal of Advanced Marine Engineering and Technology
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• 제26권3호
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• pp.307-312
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• 2002

A study on the exhaust emissions of marine diesel engine with various fuel injection timing is performed experimentally .In this paper, fuel injection timing is changed from BTDC $14^{\circ}$ to $20^{\circ}$ by $2^{\circ}$ intervals, the experiments are performed at engine speed 1800rpm and from load 0% to 100% by 25% intervals, and main measured parameters are fuel consumption rate, Soot, NOx, HC and CO emissions etc. The obtained conclusions are as follows (1) Specific fuel consumption is indicated the least value at BTDC $18^{\circ}$ of fuel injection timing and it is increased in case of leading the injection timing. (2) Soot emission is decreased in case of leading fuel injection timing and it is increased in the form of convex downwards with increasing the load. (3) NOx emission is increased in case of leading fuel injection timing and it is increased in the form of straight line nearly with increasing the load. (4) HC and CO emissions are decreased in case of leading fuel injection timing and they are changed in the form of convex downwards with increasing the load.

• Fibers and Polymers
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• 제6권4호
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• pp.318-321
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• 2005

Demand for the fabric wipes is growing continuously. Wipes in industry are used for cleaning purpose. Cleaning involves rubbing action, so it is very important to know how much frictional force is encountered during the cleaning action. In this study the effects of normal load, sliding speed on frictional characteristics of nonwoven and woven wipes, both dry and wetted with different liquids, against glass and floor tile surfaces have been reported. With the increase in the normal load the coefficient of friction goes on decreasing for both nonwoven and woven wipes and this trend is observed in both dry and wet wipes. The coefficient of friction of both nonwoven and woven wipes against glass surface is in general higher than the floor tile surface. The wipes wetted with water shows an increase in coefficient of friction as compared to dry sample, but there is reduction in the coefficient of friction when the wipe samples are wetted with vegetable oil. In case of dry wipes, the coefficient of friction in case of nonwoven wipe is higher than the woven wipe. In case of woven wipes, the ranges of coefficient of friction either due to change in liquid type, normal load or sliding speed are in general smaller than that in case of nonwoven fabrics.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 추계학술대회 논문집(Proceeding of the KOSME 2001 Autumn Annual Meeting)
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• pp.50-56
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• 2001

A study on the exhaust emissions of diesel engine with various fuel injection timing is peformed experimentally. In this paper, fuel injection timing is changed from BTDC $14^{\circ}$ to $20^{\circ}$ by $2^{\circ}$ intervals, the experiments are performed at engine speed 1800rpm and from load 25% to 100% by 25% intervals, and main measured parameters are fuel consumption rate, Soot, NOx. HC and CO emissions etc. The obtained conclusions are as follows (1) Specific fuel consumption is indicated the least value at BTDC $18^{\circ}$ of fuel injection timing and it is increased in case of leading the injection timing. (2) Soot emission is decreased in case of leading fuel injection timing and it is increased in the form of convex downwards with increasing the load. (3) $NO_x$ emission is increased in case of leading fuel injection timing and it is increased in the form of straight line nearly with increasing the load. (4) HC and CO emissions are decreased in case of leading fuel injection timing and they are changed in the form of convex downwards with increasing the load.

• 한국안전학회지
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• 제13권3호
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• pp.11-23
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• 1998

In this study, collapse test of thin-walled structure is performed under axially quasi-static and impact load in collapse characteristic to develop the optimum structural member for a light-oriented automobile. Furthermore, the energy-absorbing capacity is observed according to the variety of configuration(circular, square), aspect ratio in aluminum specimen to obtain basic data for the improved member of vehicle. In both quasi-static and impact collapse test, Al circular specimens collapse, in general, with axisymmetric mode in case of thin thickness while collapse with non-axisynmetric mode according to the thickness increase. For Al rectangular specimens, they collapse with axisymmetric mode in case of thin thickness, with mixed collapse mode according to the increase of thickness. In terms of initial max. load, Al square specimen turns out the best member among specimens, and then Al square, circular and circular with large scaling ratio, respectively. In case of quasi-static compression test, the absorbed energy per unit volume and mass shows higher in Al circular specimen, and then Al square, circular with large scaling ratio, respectively, according to shape ratio the absorbed energy per unit volume and mass in case of max. impact compression load is higher than that of static load. But the absorbed energy per unit volume and mass shows that Al circular specimen is the best member. Especially, unlike max. compression loan, the absorbed energy per unit volume and mass in impact test turns out the low value.

• 전기학회논문지
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• 제62권2호
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• pp.149-154
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• 2013

Short term load forecasting for electric power demand is essential for stable power system operation and efficient power market operation. High accuracy of the short term load forecasting can keep the power system more stable and save the power market operation cost. We propose an optimal coefficient selection method for exponential smoothing model in short term load forecasting on weekdays. In order to find the optimal coefficient of exponential smoothing model, load forecasting errors are minimized for actual electric load demand data of last three years. The proposed method are verified by case studies for last three years from 2009 to 2011. The results of case studies show that the average percentage errors of the proposed load forecasting method are improved comparing with errors of the previous methods.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.377-384
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• 2008

In the bi-directional pile load test (BD PLT) for pile load test of Mega foundation, loading capacity specification were not specified exactly. Therefore there are so many confusions and variations of maximum 2 times in loading capacity are come out. In this study, specifications of bi-directional pile load test (BD PLT) were considered. Based on cases of the bi-directional pile load test performed in domestic areas, maximum equivalent test load, test load increasing ratio and sufficiency ratio of design load were analyzed. It can be known that the loading capacity specification of bi-directional pile load test must be defined as 1-directional test load that is established as more than 2 times of design load.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2006년도 정기학술발표대회 논문집
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• pp.519-522
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• 2006

본 연구는 LCA(Life Cycle Assessment, 전과정평가) 개념을 바탕으로 토목시설의 환경성 평가를 위한 의사결정시 유용한 정보를 제공하기 위하여 사례대상으로 선정된 다목적댐 비상여수로의 위치 및 형식별로 발생 가능한 환경오염물질에 대한 환경부하량을 예측하고자 하였다. 이를 위해 LCA 기법의 이론을 고찰하고, 제안된 토목시설물의 사례대상인 다목적댐 비상여수로에 적용하기 위해 전과정 동안 발생하는 환경오염물질에 대한 환경부하량을 산출하고, 예측결과를 통하여 비상여수로의 환경성을 평가하고 친환경적인 최적대안을 도출하였다.

• 한국농공학회지
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• 제31권1호
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• pp.106-116
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• 1989

This study aims at scrutinizing the long4errn consolidation characteristics of peats sampled at three different regions of Chonbuk province. The standard consolidation test and the single load consolidation test were performed about these samples and especially in case of the latter the loading period was 350 days. The main condusions analyzed are as follows. 1. Void ratio showed much greater values than that of the general clay and was decresed greatly according to the increase of the load. 2. In case of the relationship between the sefflement and the long-term settlement time the rate of settlement increment became great according to the increase of the load step and the long4erm settlement became linely proportional to the logarithm of time alter 10 minutes. 3. The linear correlation was showed between the long4erm settlement time and the void ratio and therefore equations by regression analysis were derived in order to estimate the long-term settlement The slope of straight lines increased according th the increase of the load step and secondary consolidation coefficients ranged from 0.04-0.27. 4. The secondary consolidation coeffcient became linealy proportional to the compression index and the ratio of Ca to CC was 0.072. 5. The period required in ending the primary consolidation was about 10 minutes and alter that the secondary consolidation coefficient appeared to have constant value. Therefore the secondary consolidation coefficient was judged to be used as a significant factor in estimating the long4erm settlement. 6. In case of the single load consolidation test the secondary consolidation coefficient showed the tendancy increasing according to the increase of the consolidation pressure.