• 조명전기설비학회논문지
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• 제28권9호
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• pp.8-13
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• 2014

Currently it is major problem of electric railway with increasing drive speed such as the arc generated by the pantograph detachment and the distortion current in the motor-block high speed switching. When physical contact between the pantograph and the catenary line is separated, the pantograph detachment arcing occurs and it makes up the conductive noise to the return feeder. We made the EMTP modeling of the railway traction system and the pantograph arc by circuit elements and switches. The influence of pantograph detachment frequency is investigated by changing some frequencies. The over-current occurs in each detachment and it oscillates some time at beginning and stabilizes gradually. The magnitude of over-current is decided by instantaneous value of existing traction return current. If the detachment occurs at a point of peak value or distortion current, the over-current will be more harmful to the power systems connected with the return feeder and will become to arise with increasing detachment frequency.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.656-665
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• 1993

Two types of baby corn silk detachment systems called fixing and moving baby corn and based on applying frictional force on the silk were developed and evaluated. In the fixing mode the baby corn was fixed on a pin and a hollow frictional cylinder was moved concentrically and vertically along the baby corn towards the branch end. In the moving mode the baby corn was forced vertically towards the tip to pass through the same silk detachment cylinder. Traveling speeds of the detachment cylinder and the baby corn were 44.5 and 166.9 mm/s. In the fixing mode at silk moisture content of 91 % (w.b) silk detachment efficiencies at low and high speeds were 99.1 and 99.2%. The silk detachment efficiencies in the moving mode at low and high speeds were 96.6 and 98.5%. Damaged baby corn at low speed was less than at high speed in both modes. Minimum damage was nil in the fixing mode at low speed and the maximum was 47.5% in the moving mode at high speed. The damaged was due to ovaries r moval at the base near the joint between the baby corn and the branch.

• 조명전기설비학회논문지
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• 제27권12호
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• pp.87-92
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• 2013

In high-speed train, the EMI is generated by pantograph detachment and switching device of motor-block. Especially, the conductive noise flows through rail as return feeder influences unintended results to sub-station, transformer, etc. These phenomena were investigated by PSIM circuit analysis tool and each part of railway system is modeled by circuit elements and switching devices. Consequently, the distorted wave in return feeder current occurs by the high speed switching frequency, and the overvoltage is applied by the pantograph detachment. Also the distortion of return current is high in starting point and it decreases from the proximity of a starting point ro the end of terminal.

• Current Research on Agriculture and Life Sciences
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• 제21권
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• pp.23-29
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• 2003

Worldwide consumption of vegetable soybean bas been increasing recently, hence it is necessary to produce good quality of soybean in our farms. In the process of vegetable soybean production threshing and seperation work accounts for about 80% of overall labor. Therefore, developing of the vegetable soybean thresher is necessary to reduce the cost of labor. The purpose of this study is to acquire the basic informations to design of the vegetable soybeans-thresher. We make the experimental system which measure the physical properties and investigate the detachment forces. Also, We calculated the minimum speed of threshing cylinder. The result are as follows; 1. The average length of soybean stem is 68.2cm. 2. The length of soybean pods are seen as 61.3mm for 3 grain, 52.6mm fer 2 grains and 41.0mm fer 1 grain 3. The widths of soybean pods are seen as 14.1mm fer 3 grain, 13.8mm fer 2 grains and 13.4mm fer 1 grain. 4. The weights of soybean pods are seen as 4.1grams for 3 grains, 2.7grams for 2 grains and 1.4grams for 1 grain. 5. The average detachment forces of pods are seen as 1.5kgf for 3 grains, 1.2kgf for 2 grains and 0.8kgf for 1 grain respectively For 1 grain, the detachment force of pods ranges from 0.2kgf to 1.4kgf. For 2 grains, the minimum detachment force of pods is seen as 0.6kgf and the maximum one is seen as 2.5kgf. For 3 grains, the minimum detachment force of pods is seen as 0.7kgf and the maximum one is seen as 2.7kgf. 6. The minimum speed of threshing cylinder is shown 6.83m/s.

• Tribology and Lubricants
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• 제21권5호
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• pp.236-240
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• 2005

In order to prepare for the suitable surfaces of implants or medical devices, quantitative evaluation of adhesion between cells and biomaterials is essential. To better understand adhesion formation between cells and biomaterials, we used the cytodetachment technique which measures the adhesive force of a single cell through changing the, culture time and detachment speed. The results showed that the adhesive force could be affected by the culture time of cells on the surface of materials and the detachment speed. Moreover, there was a large discrepancy among the adhesion strength measured by similar techniques conducted on the different cells and substrates. It can be 'concluded that the variation of the force measurement technique can seriously alter the level of the force required to detach a cell on the surface of materials.

• Journal of Biosystems Engineering
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• 제27권2호
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• pp.89-96
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• 2002

The trend of consumption of vegetable soybeans is increasing because they are recognized as the clean vegetable. The works requiring the most intensive labor are threshing and seperation ones, and they form about 80% of total labour for vegetable soybeans production. It is necessary to develop the vegetable soybeans-thresher for the sake of cost down of vegetable soybeans production. The purpose of this study is to acquire the basic informations to design of the vegetable soybeans-thresher. We make the experimental system which control the speed of threshing cylinder and the teeth gap and investigate the detachment forces. The result are as follows ; The ratio of un-threshed soybeans-pod to stem after threshing work is decreasing as the threshing cylinder speed increases: 0.0% and 2.8% at 55m/s and 18m/s of threshing cylinder speed respectively. Also the ratio of un-threshed soybeans-pod to stem is shown as 2.0% below in the condition of 64~160mm of teeth gap and over 28m/s of threshing cylinder speed. The damaged pod ratio of detached soybeans after threshing work is decreasing as the threshing cylinder speed increases: 4.8% and 1.3% at 55m/s and 18m/s of threshing cylinder speed respectively. The minimum damaged pod ratio of detached soybeans are shown as 1.0%, 1.5% and 1.9% at 18m/s, 28m/s and 37m/s of threshing cylinder speed respectively. The average detachment forces of pods are shown as 1.5kg$_{f}$ for 3 grains, 1.2kg$_{f}$ for 2 grains and 0.8kg$_{f}$ for 1 grain respectively. The maximum detachment force of pod is shown as 2.7kg$_{f}$ for 3 grains. grains.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 춘계학술발표회요약집
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• pp.159-159
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• 1999

Application of the macro layer dryout model has been performed to predict CHF at inclined plates. For the identification of the detachment frequency of coalesced bubble, experiments have been performed with high-speed motion analyzer and bubble behaviors at inclined plates have been investigated. Based on the observed bubble behaviors, the detachment frequency of the coalesced bubble is measured and linear relations between detachment frequency and heat flux have been developed. In the case of 60$^{\circ}$ and 90$^{\circ}$ inclined plate, the detachment frequency decreases with the increase of heat flux. However, opposite trend has been identified in $30^{\circ}$ in-clined plate: the detachment frequency increases with the increase of heat flux. Using the cor- relation of macro layer thickness suggested by Haramura & Katto and the extrapolation of the identified linear relations, CHFs at different conditions have been predicted. According to the prediction results, CHF values are well predictable.

• 자원리싸이클링
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• 제23권6호
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• pp.30-39
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• 2014

코로나 방전 정전선별기 내에서 인쇄회로기판(Printed Circuit Board, PCB) 분쇄 입자의 이동궤도를 전산 모사하였다. 여기서 PCB입자는 전자부품 분리된 기판을 파쇄한 것으로, 대부분 구리와 FR-4(Flame Retardant Level-4)로 이루어져있다. 우선 입자가 선별기내 회전전극으로부터 탈착 지점을 계산하였으며, 중력, 원심력, 정전기력의 평형으로부터 유도되었다. 한편 탈착 후 이동궤도는 입자의 운동방정식으로부터 구한 가속도를 시간 적분하여 계산하였다. 시뮬레이션 변수는 입자의 크기, 공급전압의 세기, 회전전극속도 및 유도전극 각도로 하였다. 입자 이동궤도에 미치는 영향은 구리 입자의 경우에는 회전속도가 주요 변수였으나, 반면 FR-4 입자의 경우에는 상기 모든 변수에 영향을 받는 것으로 나타났다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.94-100
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• 2002

During the last years, great progress has been made in the fields of welding power sources and filler materials for the MIG-welding of magnesium alloys. This advice resulted in a better welding process, md, therefore, in highly improved welding results. Furthermore the gap between short-circuiting- and spray-arc-trunsfer could be closed by the triggered short-circuiting- and the short-circuiting-arc with pulse overlay. A crucial contribution to the welding process is the energy input into the filler material. Many problems result from the physical properties of magnesium, for instance its narrow interval between melting point 600$^{\circ}C$ and vaporization point 1100$^{\circ}C$. The energy input into the filler material has to be regulated in such a way that the wire will melt but not vaporize. For th is reason, special characteristics of power sources hue been examined and optimized with the help of high-speed-photographs of the welding process with particular consideration of the drop detachment. An important improvement of the weld seam profile has been achieved by using filler material of only 1.2 mm in diameter. The experiments hue been made with 2.5 mm thick extruded profiles of AZ31 and AZ6l. The results of tensile testing showed strength values of 80 to 100% of the base metal. B ending angles up to 60$^{\circ}$ have been reached. The fatigue strength under reversed bending of the examined magnesium alloys after welding reaches 50% of the strength of the base metal. When the seam reinforcement is ground of the fatigue strength can be raised up to 75% of the base metal.

• 대한기계학회논문집B
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• 제38권4호
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• pp.337-346
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• 2014

본 연구는 주기적 강제 진동이 가해지는 표면의 액적 모드 특성과 표면에 놓인 액적의 제거에 대한 조건을 실험적으로 이해하는 것을 목적으로 하고 있다. 액적의 거동을 명확하게 관찰하기 위해 아크릴 표면에 Teflon 코팅을 진행하여 접촉각을 높였고, 히스테리시스는 25도 이내로 진행하여 액적의 거동이 보다 쉽게 진행되도록 하였다. 본 실험은 먼지가 적은 청정실에서 실험이 진행되었다. 제작된 소수성 표면에 놓인 액적의 실제 공진 주파수를 예측하기 위해 이론 및 실험적 해석을 통해 두 접근방법의 타당성을 파악하였으며, 두 개의 초고속카메라를 액적의 상면과 측면에 설치하여 2가지 측면에서 액적의 다양한 형상 변형 특성- 모드 형상, 분리, 미소 액적의 발생, 그리고 좌우 비틀림의 특성을 관찰하였다. 이론 값 비교결과 실제 공진 주파수 값들의 차이가 약 18% 이하로 관찰되었으며, 이러한 차이는 접촉선 마찰, 비선형 벽 고착, 실험의 불확실성 등에 가장 큰 영향을 받는 것으로 판단된다. 사용된 스피커에 상대적으로 낮은 전압을 인가할 경우 액적의 접촉선은 고정된 상태에서 좌우 대칭적인 액적 형상진동이 나타났다. 반면, 높은 전압을 인가할 경우 액적의 접촉선은 비고정된 상태가 되면서 더 활발한 형상 진동이 나타났다. 가진 주파수가 모드 주파수와 일치할 경우에는 액적의 로브 크기가 주변부 주파수 일 때 보다 비교적으로 컸으며, 같은 전압을 인가 할 경우, 표면에 놓인 액적의 미소 액적 발생 및 완전한 제거는 2차 모드에서만 진행되는 것을 실험을 통해 규명하였다.