• 한국정밀공학회지
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• 제11권2호
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• pp.182-188
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• 1994

This expermintal study is intended to investigate he development of flank wear in turning os SUS304 which is used in industrial applications and is acknowledged as a machining difficult material. In cutting process, change of velocity, change of feed, and change of depth of cut were investigated about the effect of flank wear, and slenderness ratio is also investigated. The variations of unit cutting force with the change of rake angle and the change of uncut chip area are observed. The friction angles are calculated for the change friction force and observed. The friction angles are calculated for the change friction force and normal forcd on the different rake angles. From this experimental study, the following results can be said. 1. Under the high cutting speed condition, the flaank wear is affected by the feed and depth of cut, but the influence of feed and depth of cut to the flank wear is reduced when the velocity is low. 2. The smaller slenderness ratio is, the shorter the tool life results in high cutting speed, and the lower cutting speed is, the lower the effect of slenderness ratio to the flank wear is. 3. Using the characteristics of force-RMS, the flank wear of a tool can be detected. There are almost no differences between the RMS characteristics of cutting force and feed force.

• Journal of Electrochemical Science and Technology
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• 제15권3호
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• pp.373-387
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• 2024

The layout of the cathode flow field largely determines the net output power of the proton exchange membrane fuel cell (PEMFC). To make the normal mass transfer effect best, the longitudinal channel was waved based on four serpentine flow channels, and the effects of sag depth and longitudinal channel width on the output efficiency of the cell were explored. The results show that the wave channel design systematically enhances the forced convection between adjacent channels, which can prevent a large zone of oxygen starvation zone at the outlet of the channel. The increase of the normal velocity in the gas transmission process will inevitably induce a significant enhancement of the mass transfer effect and obtain a higher current density in the reaction zone. For the longitudinal channel width, it is found that increasing its size in the effective range can greatly reduce the channel pressure drop without reducing the output power, thereby improving the overall efficiency. When the sag depth and longitudinal channel width gradient are 0.6 mm and 0.2 mm respectively, PEMFC can obtain the best comprehensive performance.

• 한국환경복원기술학회지
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• 제8권4호
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• pp.12-22
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• 2005

The purpose of this study is to select suitable planting base for the mat-type rooftop greening in order to popularize rooftop greening system easily. The experiment was conducted from 2004 June to 2005 May under several conditions; 4 soil depths under mats(2cm, 5cm, 10cm, 15cm), two soil mixtures(natural soil 80%+leaf mold 20%, artificial soil) and two light conditions(full sun place, 20% shaded place). In this experiment, 3 types of mats were used ; the herbaceous plants mat(11 plants inclusive of Lotus corniculatus L., Silene armeria L.), the lawn mat with Festica arundinacea and Sedum mat with Sedum kamtschaticum, Sedum sarmentosum, Sedum oryzifolium, Sedum middendorffianum. The result is as follows; in the mat-type rooftop greening, the herbaceous plants mat, lawn mat and sedum mat are the similar number of plant and effect of greening on soil depth 2cm, 5cm and 10cm, 15cm. So suitable soil depth of rooftop greening is 10cm for the load and economical factor. Thus the mat-type rooftop greening possible planting base depth of all 13cm as soil depth 10cm and mat depth 3cm. As soil mixtures, the number and growth of plants were better mat and 'natural soil 80% +leaf mold 20%' than mat and artificial soil. In herbaceous plants mat, Silene armeria L., Dianthus chinensis, Centaurea cyanus L., Lotus corniculatus L. are survival in full sun place and Silene armeria L., Dianthus chinensis, Centaurea cyanus L. are survival in 20% shaded place. In conclusion, selection of suitable soil mixtures and plants is possible extensive management rooftop greening with effect of continuous greening. The mat-type rooftop greening are lightweight and simple preparation without management and can popularize readily.

• Current Research on Agriculture and Life Sciences
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• 제21권
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• pp.31-37
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• 2003

나리속(屬) 식물의 엽초는 품종에 따라 엽위별 형태와 숫자가 큰 차이를 보여 품종별로 식재깊이에 따른 엽초수를 조사하고, 엽초를 제거한 후 생육 반응을 알아보았다. 품종별 엽초는 0cm로 식재한 경우 'Jolanda'는 6매엽, 'Dream Land'는 5매엽과 'Casablanca'는 11매엽으로, 6cm로 식재한 경우 'Jolanda'는 6매엽, 'Dream Land'는 5매엽과 'Casablanca'는 14매엽으로 밝혀져 'Jolanda'와 'Dream Land'는 식재깊이에 따라 엽초수의 차이가 없었으나 'Casablanca'는 6cm로 식재한 것이 0cm로 식재한 것에 비해 엽초가 3장이 더 많아졌다, 한편 엽초를 제거함으로써 'Le Reve'와 'Casablanca' 두 품종 모두 초장이 작아졌으며 stem root의 생육이 나빠졌다. basal root의 생육과 꽃수는 품종별로 다른 양상을 나타냈으며 줄기 직경, 개화소요일수와 꽃의 크기는 차이가 없었다.

• 한국자동차공학회논문집
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• 제21권5호
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• pp.74-81
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• 2013

The high-speed machining in the manufacturing industry field has been widely applied for parts of vehicles, aircraft, ships, electronics, etc., recently, because the effect of cost savings for shortening processing time and improving productivity is great. The purpose in this study is to investigate the effect of cutting depth on the surface roughness of workpiece with the spindle rotational speed and feed rate of high-speed machines as a parameter to find the optimal depth in the finishing for ball end mill of the aluminum alloy 7075 which is used much in aircraft parts. When the cutting depth for the respective feed rate and spindle rotational speed is varied from 0.1 mm to 0.7 mm at intervals of 0.2 mm in the wet finishing of the aluminum alloy 7075 by the insoluble cutting oils and high-speed machining used in the rough machining of previous study, the surface roughness values and the cutting temperature are measured. In addition, the cutting surface shapes of test specimens are observed by optical microscope and compared with respectively. It is found that the surface roughness values and the temperature generated during machining are increased as the feed rate and cutting depth are raised, but those are decreased as the spindle rotational speed is increased.

• The Journal of Advanced Prosthodontics
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• 제7권2호
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• pp.115-121
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• 2015

PURPOSE. This study aimed to evaluate the effect of implant thread depth on primary stability in low density bone. MATERIALS AND METHODS. The insertion torque was measured by inserting Ti implants with different thread depths into solid rigid polyurethane blocks (Sawbones) with three different bone densities ($0.16g/cm^3$, $0.24g/cm^3$, and $0.32g/cm^3$). The insertion torque value was evaluated with a surgical engine. The static compressive strength was measured with a universal testing machine (UTM) and the Ti implants were aligned at $30^{\circ}$ against the loading direction of the UTM. After the static compressive strength test, the Ti implants were analyzed with a Measurescope. RESULTS. The Ti implants with deeper thread depth showed statistically higher mean insertion torque values (P<.001). Groups A and group B had similar maximum static compressive strengths, as did groups C and D (P>.05). After the static compressive strength, the thread shape of the Ti implants with deeper thread depth did not show any breakage but did show deformation of the implant body and abutment. CONCLUSION. The implants with deeper thread depth had higher mean insertion torque values but not lower compressive strength. The deep threads had a mechanical stability. Implants with deeper thread depth may increase the primary stability in areas of poor quality bone without decreasing mechanical strength.

• 전기학회논문지
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• 제63권1호
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• pp.99-107
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• 2014

In this paper, a landmark based localization system using a Kinect sensor is proposed and evaluated with the implemented system for precise and autonomous navigation of low cost robots. The proposed localization method finds the positions of landmark on the image plane and the depth value using color and depth images. The coordinates transforms are defined using the depth value. Using coordinate transformation, the position in the image plane is transformed to the position in the body frame. The ranges between the landmarks and the Kinect sensor are the norm of the landmark positions in body frame. The Kinect sensor position is computed using the tri-lateral whose inputs are the ranges and the known landmark positions. In addition, a new matching method using the pin hole model is proposed to reduce the mismatch between depth and color images. Furthermore, a height error compensation method using the relationship between the body frame and real world coordinates is proposed to reduce the effect of wrong leveling. The error analysis are also given to find out the effect of focal length, principal point and depth value to the range. The experiments using 2D bar code with the implemented system show that the position with less than 3cm error is obtained in enclosed space($3,500mm{\times}3,000mm{\times}2,500mm$).

• 디지털융복합연구
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• 제17권8호
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• pp.205-219
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• 2019

가상환경을 활용한 시뮬레이션과 같은 교육, 훈련 등이 다양한 분야에 적용되고 있는 만큼 그 활용성은 무궁무진하다. 하지만 가상환경에서 훈련을 함에 있어 깊이지각의 과소추정이 존재하며, 이는 향후 훈련의 타당도에 문제가 될 수 있다. 관련 연구에서는 이를 해결하기 위해 하향식 보정방안을 적용하여 문제를 해결하려 하였으나 그 결과가 학습에 의한 효과인지 실제 지각의 변화인지에 대한 구분이 어렵다는 단점이 있다. 이에 본 연구에서는 실험결과를 통하여 공간 구성요수 중 비례가 깊이지각에 유의미한 영향을 끼치는 것을 확인하였으며, 비례와 깊이지각 단서를 함께 보정하여 실험할 경우 깊이지각 중 크기지각이 매우 정확해진다는 것을 확인하였다. 이에 본 연구에서는 깊이지각의 정확도를 높이기 위해 공간 구성요소와 깊이지각을 활용한 보정방안을 제시한다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.1155-1158
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• 2006

This paper presents a study on the construction condition and environmental effect of deep soil mixing. Construction condition means the difference in unconfined compressive strength with respect to the depth and location of samples. Environmental effect means alkalinity diffused from soil stabilizer. The experimental results indicate that the unconfined compressive strength vary with respect to the depth, and doesn't show consistency pattern. So, in field application we must decide a mixing ratio enough to satisfy the least unconfined compressive strength. The difference in unconfined compressive strength with respect to the location of samples is negligible. The generation of alkalinity from soil stabilizer is reduced by permeating in non-improved soil and it is expected that the diffusion of alkalinity has no environmental effect on soil and ground water.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권4호
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• pp.187-191
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• 2004

In this work, we used the PCID simulator for simulation of solar cell and examined the effect of front-back surface recombination velocity, minority carrier diffusion length, junction depth and emitter sheet-resistance. As the effect of base thickness, the efficiency decreased by the increase in series resistance with the increase of the thickness and found decrease in efficiency by decrease of the current as the effect of the recombination. Also, as the effect of base resistivity, the efficiency increased somewhat with the decrease in resistivity, but when the resistivity exceeded certain value, the efficiency decreased as a increase in the recombination ratio. The optimum efficiency was obtained at the resistivity 0.5 $\Omega$-cm, and thickness $100\mu\textrm{m}$. We have successfully achieved 10.8% and 13.7% efficiency large area($103mm{\times}103mm$) mono-crystalline silicon solar cells without and with PECVD silicon nitride antireflection coating.