• 한국유체기계학회 논문집
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• 제13권3호
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• pp.37-42
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• 2010

This study investigated on details of flow characteristics of a multi-blade fan for domestic ventilation. Experiments and analysis were carried out to describe on flow pattern with variations of cut-off angle near the scroll housing throat, which were performed by PIV measurement for the flow field and by total pressure probes. The stagnation point at cut-off region of the fan moves to the exit of the scroll housing as the cut-off angle increases. The movement of stagnation point and the variation of throat area of the scroll housing influence to the distribution of velocity magnitude at the exit of the fan. Furthermore, a large distortion of the velocity distribution at the scroll exit causes to increase mixing loss along the flow path.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 춘계학술대회 논문집
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• pp.15-20
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• 1999

In this study, the effects of the maximum grit depth of cut on the grinding characteristics were investigated. And AE signals produced during grinding processes have been studied to find out the appropriate AE parameters for assessing grinding processes. S45C steel has been ground under the conditions yielding removal rate of workpiece, 100, 200, 300 and 400rnm$^3$/min which was achived by altering workpiece velocity($\upsilon$) and apparent depth of cut(Z). According to the experimental results, the value of surface roughness increases but grinding power, energy rate of AE signal(AErms$^2$) and specific grinding energy consumed decrease with increase of the maximum grit depth of cut.

• 한국소음진동공학회논문집
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• 제18권12호
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• pp.1270-1277
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• 2008

For designing intensity modulation type optical microphone, the irradiance distribution which can be applied to inclined-cut geometrical configuration is suggested. The model is important in analysis of response characteristics for intensity modulation type optical microphone. To overcome low sensitivity problem in intensity modulation type optical microphone, inclined-cut optical fiber is considered here. Based on optical geometry, the inclined-cut optical fiber sensor is designed and fabricated. The experiments are carried out to evaluate sensor performance.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.467-474
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• 2002

Colluvial sell has a very unique deformation property, particularly when it is subject to the cutting work entailed in a variety of construction. In this study, the cut slope tying on a colluvial layer in which the transmission tower had been installed were investigated to find out the cause of deformation. In-situ tests such as boring, surface-wave analysis (MASW) were employed to look into the physical composition of underground layers and FEM including LEM were carried out to simulate the construction steps. The result shows that the stress relaxation followed by road construction induced the deformation of the slope and damage in the foundation of the transmission tower.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 추계학술대회 논문집
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• pp.249-254
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• 1998

This paper describes the control methods to cut out the NFB(No Fuse Breaker) of shorted load in the auxiliary power supply, Generally, when the short-circuit occurs in the load of the auxiliary power supply, the auxiliary power supply stops the operation according to the protection sequence. Finally, the other auxiliary power supply stops the operation by the same fault, To resolve this problem, we suggest the control method to trip the NFB of shorted load. That is, when the short circuit occurs, the controller changes control mode from voltage mode to current mode without the operation of output contactor(SIVK) in the auxiliary power supply. The auxiliary power supply provides a large current for the short-circuit load. After some time, the NFB of the short-circuit load is cut off and the auxiliary power supply Provides stable voltage for the loads except for the short-circuit load.

• 정보보호학회논문지
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• 제16권5호
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• pp.113-118
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• 2006

가명을 이용한 시스템에서는 가명을 발급한 기관에게도 사용자의 익명성이 유지되어야 하며, 다만 정책적으로 사용자가 규칙을 어겼을 때는 가명으로부터 사용자의 신원정보를 추적할 수 있어야 한다. 이 논문에서는 m--out-of-n oblivious transfer와 cut-and-choose 기술을 이용하여 추적 가능한 가명 은닉 획득 프로토콜을 제안한다.

• Journal of the Korean Wood Science and Technology
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• 제26권1호
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• pp.38-50
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• 1998

Laser cutting tests were conducted to investigate the laser cutting characteristics of solid woods such as 25mm-thick white oak(Quercus acutissima) and maple(Acer mono), and wood-based panels such as 15mm-thick medium density fiberboard and particleboard. Test variables were laser power, cutting speed, grain direction, and moisture content. Specific cutting energy was measured and the qualities of cut surface were estimated in constant laser power. Specific cutting energy of white oak was larger than that of maple, and specific cutting energy of medium density fiberboard was smaller than that of particleboard. For both white oak and maple, specific cutting energy of green wood was smaller than that of air-dried wood because weight loss of moisture evaporation in green wood was larger than that in air-dried wood. In laser-cut surface, wood cells were not deformed and damaged, but in circular saw-cut surface fibers were pushed out and cut, and wood cells were deformed severely. However, mechanical surface roughness of saw-cut surface was smoother than that of laser-cut surface because of the existence of undeformed cell cavity in laser-cut surface.

• 한국정밀공학회지
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• 제5권1호
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• pp.63-70
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• 1988

Laser cutting system uses a gas jet to remove the molten or varpozed material from the workpiece. The quality of the laser cut can be strongly influenced by the gas flow charac- teristics formed through the nozzle. Laser cutting experiments were carried out for SS41 and SUS 304 to investigate the relationship between cut quality and cutting pressure. The cutting speed, nozzle pressure and nozzle to workpiece distance were also considered. The cut specimens were inspected by various manners such as dross observation, surface roughness test and kerf width measurement. Based on the data of pressure measurement on workpiece and the results of cut surface inspection, the influence of the considered cutting conditions on cut quality could be evaluated. The results of this study will be valuable in planning the optimal laser cutting process and in designing the laser cutting nozzle.

• 지질공학
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• 제11권1호
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• pp.101-113
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• 2001

절취암의 물량산정과 사석의 절취 효율성을 판단하기 위한 목적으로 욕망산 인근지역의 지반조사를 실시하였다. 조사지역은 경상분지 동남부의 지질구조를 지배하는 양산단층대의 말단에 위치하여 안산암질암, 유문암질암 등의 화산암류와 이를 관입하고 있는 화강암으로 구성되어 있으며, 북북동-남남서 방향의 우수향 주향이동단층에 의해 규제되고 있다. 단층들은 분포된 절리의 간격과 빈도수 그리고 절리면 압축강도에 직접적인 영향을 끼치고 있다. 절리빈도는 단층면 인접지역에서 최대치를 나타내고 단층에서 멀어짐에 따라 감소된다. 지질조사를 기초로하여 구조도를 작성하고 이를 활용한 채취물량의 산정 결과 현장의 공사에 필요한 암편의 최소 크기를 고려할 때 채취 물량은 암반(기반암)체적의 61%인 4,018,000m$^3$이며, 표토와 풍화암이 포함된 욕망산 체적의 48%에 해당된다.

• Hip & pelvis
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• 제30권4호
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• pp.269-275
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• 2018

Purpose: The purpose of this study is to describe a method of inserting cement in the femoral head before fixation with dynamic hip screw to prevent screw cut out due to osteoporosis and to evaluate its clinical outcome in these patients. Materials and Methods: In this prospective study, 30 patients aged 60 years and older with intertrochanteric fracture were included. Bone mineral density was measured. After reaming of the femoral head and neck with a triple reamer and polymethyl methacrylate, bone cement was introduced into the femoral head using a customized nozzle and a barrel fitted on a cement gun. A Richard screw was inserted and the plate was fixed over the femoral shaft. Patients were mobilized and clinical outcomes were rated using the Salvati and Wilson's scoring system. Results: More patients included in this study were between 66 and 70 years old than any other age group. The most common fracture according to the Orthopaedic Trauma Association classification was type 31A2.2 (46.7%). The T-score was found to be $-2.506{\pm}0.22$ (mean${\pm}$standard deviation); all patients were within the range of -2.0 to -2.8. The duration of radiological union was $13.67{\pm}1.77$ weeks. Salvati and Wilson's scoring at 12 months of follow up was $30.96{\pm}4.97$. The majority of patients were able to perform their normal routine activities; none experienced implant failure or screw cut out. Conclusion: Bone cement augmentation may effectively prevent osteoporosis-related hardware complications like screw cut out in elderly patients experiencing intertrochanteric fractures.