• 대한기계학회논문집B
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• 제41권3호
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• pp.211-219
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• 2017

본 연구에서는 전산유체역학 프로그램을 이용하여 순환형공기분급기 내부유동 및 입자거동을 해석하였다. 주날개 및 분급날개의 회전속도 조건을 변화시키며 이에 따른 등급분급효율, 절단입경 및 분급첨예도 변화를 예측하였다. 주날개의 회전속도를 제어함으로써, 절단입경을 증가시킬 수 있었으나, 오염토양 분급에 적용할 수 있을 정도의 정확도를 확보할 수 없었다. 반면, 분급날개의 회전속도를 증가시킴으로써, 절단입경을 감소시킬 수 있었으며, 보다 정확하게 입자를 선별할 수 있었다. 결과적으로 주날개와 분급날개를 동시에 사용할 경우, 높은 분급첨예도 결과를 보이며, 우수한 분급특성을 유지할 수 있었다.

• 한국식품저장유통학회지
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• 제19권2호
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• pp.173-177
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• 2012

신선절단 사과와 엽채류의 품질에 절단방법이 미치는 영향을 구명하기 위하여, 사과는 sharp knife나 dull knife로 절단하고, 양배추와 결구상추는 hand나 knife cutting 및 knife로 샐러드용 크기나 채썰기로 절단하고 각 절단품의 품질특성을 비교 조사하였다. 신선절단 사과의 갈변도와 과육경도는 dull knife보다 sharp knife로 절단한 경우에 유의적으로 낮고 높게 유지되었다. 반면에 신선절단 사과의 가용성 고형분 함량과 pH는 절단용 칼날의 날카로움에 따른 유의적인 차이를 보이지 않았다. 신선절단 양배추와 결구상추의 갈변도는 hand cutting보다 knife cutting에서, 샐러드용 크기보다 세절인 채썰기한 경우에서 유의적으로 낮은 수준을 나타내었다. 이로써, 신선절단품 제조시 조직손상을 크게 하는 절단방법이 사과의 갈변과 연화를, 양배추와 결구상추의 갈변을 촉진시키는 것으로 확인되었고, 고품질 제품을 위해 조직손상을 최소화할 수 있는 기술이 적용되어야 할 것으로 판단된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1440-1443
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• 2004

Shearing including punching, blanking, trimming, slitting, etc is one of the most frequently used processes in sheet metal manufacturing. It has been widely used for manufacturing autobody, electronic components, aircraftbody, etc. In this paper, it has been researched by the experiment to examine the effect of burr height corresponding to die clearance, cutting angle, tool sharpness, etc. This paper presents the experimental results with using Al alloy sheet.

• Asian-Australasian Journal of Animal Sciences
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• 제17권10호
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• pp.1465-1471
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• 2004

A trial was conducted to determine the effect of abrasive strips and abrasive paint in layer cages on claw length and claw sharpness, foot condition, feather cover and mortality of hens. During the preparation of the cages for the experiment it was simpler and took less time to apply the pre-prepared paint with a spatula to the egg guard compared to sticking the abrasive strips onto the egg guard. Fitting the strips took longer because it had to be cut from a 25 mm roll, cut into the appropriate lengths, the tape backing removed and then stuck onto the egg guard section. Abrasive paint was more effective as a claw shortener than abrasive strips. The birds using the abrasive paint had the shortest (p<0.05) claw length and lowest (p<0.05) claw sharpness. One of the original reasons for reducing claw length with claw shorteners was to reduce mortality by minimising skin skin abrasions caused by the claws. Surprisingly hen mortality from prolapse and cannibalism was higher (p<0.05) in cages fitted with abrasives. There are no other reports in the literature showing an increase in prolapse and cannibalism from hens using abrasives.

• 한국기계가공학회지
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• 제6권2호
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• pp.17-21
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• 2007

Shearing including punching, blanking, trimming, slitting, etc is one of the most frequently used processes in sheet metal manufacturing. It has been widely used for manufacturing autobody, electronic components, aircraftbody, etc. In this paper, it has been researched by the experiment to examine the effect of burr height corresponding to die clearance, cutting angle, tool sharpness, etc. This paper presents the experimental results with using Al alloy sheet.

• Journal of Mechanical Science and Technology
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• 제17권2호
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• pp.239-245
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• 2003

Ultra precision diamond cutting is a very efficient manufacturing method for optical parts such as HOE, Fresnel lenses, diffraction lenses, and others. During micro cutting, the rake angle is likely to become negative because the tool edge radius is considerably large compared to the sub-micrometer-order depth of cut. Depending on the ratio of the tool edge radius to the depth of cut, different micro-cutting mechanism modes appear. Therefore, the tool edge sharpness is the most important factor which affects the qualities of machined parts. That is why diamond, especially monocrystal diamond which has the sharpest edge among all other materials, is widely used in micro-cutting. The majar issue is regarding the minimum (critical) depth of cut needed to obtain continuous chips during the cutting process. In this paper, the micro machinability near the critical depth of cut is investigated in micro grooving with a diamond tool. The experimental results show the characteristics of micro-cutting in terms of cutting force ratio (Fx/Fy), chip shape, surface roughness, and surface hardening nea. the critical depth of cut.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.376-381
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• 2003

Ultra precision diamond cutting is a very efficient manufacturing method for optical parts such as HOE, Fresnel lenses, diffraction lenses, and others. During micro cutting, the rake angle is likely to become negative because the tool edge radius is considerably large compared to the sub-micrometer-order depth of cut. Depending on the ratio of the tool edge radius to the depth of cut, different micro-cutting mechanism modes appear. Therefore, the tool edge sharpness is the most important factor affecting the qualities of machined parts. That is why diamond especially mono-crystal diamond, which has the sharpest edge among all other materials is widely used in micro-cutting. The question arises, given a diamond tool, what is the minimum (critical) depth of cut to get continuous chips while in the cutting process\ulcorner In this paper, the micro machinability around the critical depth of cut is investigated in micro grooving with a diamond tool, and introduce the minimizing method of cutting depth using vibration cutting. The experimental results show the characteristics of micro cutting in terms of cutting force ratio (Fx/Fy), chip shape, surface roughness, and surface hardeing around the critical depth of cut.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.951-954
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• 2000

This paper presents a new cutting method, i.e. diamond cutting, aided by electrolysis, in order to cut ferrous materials with diamond tools. Diamond cutting is widely applied in manufacturing ultraprecision parts such as magnetic disk, polygon mirror, spherical/non-spherical mirror and copier drum, etc. because of the diamond tool edge sharpness. In general, however, diamond cutting cannot be applied to cutting steels, because diamond tools wear excessively in cutting iron based materials like steel due to their high chemical interaction with iron in high temperature. In order to suppress the diffusion of carbon from the diamond tool and to reduce increase of cutting force due to size effect, we attempt to change chemically the compositions of iron based materials using electrolysis in a limited part which will be soon cut. Through experiments under several micro-machining and electrolysis conditions, cutting using electrolysis, compared to conventional cutting, was found to result in a great decrease of the cutting force, a better surface and much less wear tool.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.980-983
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• 2002

In micro-machining, diamond tool is commonly used because it brings much better micro-machinability due to its edge sharpness. However, it is a big question even how thinly the sharp edge of a diamond tool can cut a ship from the workpiece surface. This paper is to investigate the critical cutting depth, at which the dominant cutting mode changes from chip formation to burnishing or vice versa, for a given edge radius. The theoretically critical cutting depth is 0.25$\mu\textrm{m}$(0.8$\mu\textrm{m}$) in cutting using a square type(V-type) diamond tool that has edge radius of 1$\mu\textrm{m}$(1.5$\mu\textrm{m}$). Experimentally, the dominant cutting mode changes and cutting surface becomes better at critical cutting depth. To get high quality surface, depth of cut must be critical cutting depth because less plastically deformed substrate is left on the surface.

• 대한토목학회논문집
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• 제43권1호
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• pp.21-32
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• 2023

산림지역은 세류간침식이 지배적인 반면, 지표 교란지역은 세류의 발달과 확장에 의한 침식이 두드러지게 증가한다. 본 연구는 급경사에서 세류 발달과 미세지형 변화의 특성을 파악하고자 강우와 유입수 모의에 따른 토양침식 실험을 수행한 것이다. 세류의 단면과 체적, 세류밀도, 세류차수, 세류예도와 같은 미세지형의 특성인자들은 사면의 경사와 위치(상부 또는 하부)에 따른 분석이 이루어졌다. 강우모의에 의해 동시다발적으로 절개된 세류들의 두부침식은 빠른 속도로 상류로 이동하였고, 무작위으로 발달한 세류들은 서로 연결되면서 깊고 넓게 확장하였다. 세류가 하류방향으로 진화함에 따라 횡단면적은 점차적으로 증가하였다. 세류 체적은 유출토사 체적의 약 78 %를 차지하여, 세류침식이 세류간침식보다 토사유출량 기여도가 큼을 확인하였다. 경사가 증가함에 따라 세류차수의 증가는 둔화되지만, 세류의 총길이와 밀도는 전반적으로 증가하였다. 경사 15°에서 20°로 증가하면서 세류의 측벽확장보다 하상절개가 상대적으로 커지면서 세류예도가 1.6배로 증가하였다. 하사면의 유출계수는 상사면보다 12.3 % 적었으며, 이는 세류 확장에 의한 형상 변화와 심토의 노출이 침투를 증가시켰던 것으로 평가된다. 세류가 수반된 토사유출은 경사가 급할수록 전반적으로 증가하지만, 세류진화 과정에서 국부적인 합류와 확장으로 강화된 세류의 수리학적 유속에 직접적인 영향을 받았다.