• 지구물리와물리탐사
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• 제18권2호
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• pp.39-53
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• 2015

동해 울릉분지 남서주변부에서 취득한 2차원 다중채널 탄성파 탐사자료 해석결과에 의하면 연구지역에는 U자 또는 V자 형태의 침식충전구조가 다양한 규모로 발달한다. 시추공 자료에 의하면 침식충전구조를 채우고 있는 퇴적물은 주로 세립질 퇴적물로 구성되며, 탄성파 단면상에서 특정 내부 구조를 보여주지 않는 투명 혹은 반투명 음향상 특징을 보여주는 것과 잘 대비된다. 상기 특징을 갖는 침식충전구조는 연구지역에 분포하는 4개의 퇴적층군 중 후기 마이오세 분지변형 기간 동안 퇴적된 횡압력 동시성 퇴적층군(MSQ3)에 우세하게 분포한다. 이와 같은 침식충전구조는 발달규모와 시기에 따라 3개의 그룹으로 구분된다. 그룹 I에 속하는 침식충전구조는 돌고래 구조발달 시기에 대비되며, 소규모로 분포한다. 그룹 II에 포함되는 침식충전구조는 돌고래 구조와 고래V 구조가 동시에 발달한 것으로 알려진 시기에 형성되었으며, 발달개수와 규모가 그룹 I에 비해 크게 증가하였다. 그룹 III는 돌고래 구조의 발달은 점차 약화되었으나 고래V 구조의 영향은 지속된 시기에 형성되었으며, 침식충전구조의 발달개수와 규모는 그룹 II에 비해 크게 감소하였다. 상기 제시된 침식충전구조의 분포양상, 발달규모, 내부충전물의 특징에 의하면 연구지역에 분포하는 침식충전구조는 해저협곡으로 해석되며, 울릉분지의 닫힘과 관련된 지구조운동과 그에 따른 퇴적물 공급량의 영향을 받아 형성된 것으로 해석된다.

• Journal of Magnetics
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• 제19권1호
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• pp.15-19
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• 2014

In this study, for 6-20 MeV electron beam energy occurring in a linear accelerator, the authors attempted to investigate the relation between the effective source-skin distance and the relation between the radiation field and the effective source-skin distance. The equipment used included a 6-20 MeV electron beam from a linear accelerator, and the distance was measured by a ionization chamber targeting the solid phantom. The measurement method for the effective source-skin distance according to the size of the radiation field changes the source-skin distance (100, 105, 110, 115 cm) for the electron beam energy (6, 9, 12, 16, 20 MeV). The effective source-skin distance was measured using the method proposed by Faiz Khan, measuring the dose according to each radiation field ($6{\times}6$, $10{\times}10$, $15{\times}150$, $20{\times}20cm^2$) at the maximum dose depth (1.3, 2.05, 2.7, 2.45, 1.8 cm, respectively) of each energy. In addition, the effective source-skin distance when cut-out blocks ($6{\times}6$, $10{\times}10$, $15{\times}15cm^2$) were used and the effective source-skin distance when they were not used, was measured and compared. The research results showed that the effective source-skin distance was increased according to the increase of the radiation field at the same amount of energy. In addition, the minimum distance was 60.4 cm when the 6 MeV electron beams were used with $6{\times}6$ cut-out blocks and the maximum distance was 87.2 cm when the 6 MeV electron beams were used with $20{\times}20$ cut-out blocks; thus, the largest difference between both of these was 26.8 cm. When comparing the before and after the using the $6{\times}6$ cut-out block, the difference between both was 8.2 cm in 6 MeV electron beam energy and was 2.1 cm in 20 MeV. Thus, the results showed that the difference was reduced according to an increase in the energy. In addition, in the comparative experiments performed by changing the size of the cut-out block at 6 MeV, the results showed that the source-skin distance was 8.2 cm when the size of the cut-out block was $6{\times}6$, 2.5 cm when the size of the cut-out block was $10{\times}10$, and 21.4 cm when the size of the cut-out block $15{\times}15$. In conclusion, it is recommended that the actual measurement is used for each energy and radiation field in the clinical dose measurement and for the measurement of the effective source-skin distance using cut-out blocks.

• Elastomers and Composites
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• 제36권4호
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• pp.255-261
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• 2001

Precut을 가지고 있는 고무 시편에서 서로 다른 온도에서 인장 강도의 영향을 조사하였다. 온도 조건에 따라 precut이 있는 시편과 precut이 없는 시편의 인장 강도는 서로 다른 거동을 보였다. $80^{\circ}C$에서는 임계 Precut 크기보다 더 큰 precut를 가지는 시편은 상온에서 시편보다 높은 인장 강도를 보였다. 상온에서 측정한 시편에 비하며 $80^{\circ}C$에서 측정한 시편은 잘 발달된 2차 균열들을 가지고 있는 반면, $110^{\circ}C$에서 측정한 시편의 경우 2차 균열들이 명확하게 발달하지 못하였다. 서로 다른 온도에서 인장강도의 차이는 인장시 발달된 결정화도와 균열 끝 부분에서 형성된 미세 균열 형상과 관계가 있는 것으로 보인다.

• Geomechanics and Engineering
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• 제15권3호
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• pp.811-822
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• 2018

Chip size distribution can be used to evaluate the cutting efficiency and to characterize the cutting behavior of rock during cutting and fragmentation process. In this study, a series of linear cutting tests was performed to investigate the effect of cutting conditions (specifically cut spacing and penetration depth) on the production and size distribution of rock chips. Linyi sandstone from China was used in the linear cutting tests. After each run of linear cutting machine test, the rock chips were collected and their size distribution was analyzed using a sieving test and image processing. Image processing can rapidly and cost-effectively provide useful information of size distribution. Rosin-Rammer distribution pamameters, the coarseness index and the coefficients of uniformity and curvature were determined by image processing for different cutting conditions. The size of the rock chips was greatest at the optimum cut spacing, and the size distribution parameters were highly correlated with cutter forces and specific energy.

• 대한금속재료학회지
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• 제48권9호
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• pp.847-855
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• 2010

The grain size of a cross-section of $8{\mu}m$-thick copper film was determined by electron backscatter diffraction analysis. Grain size distribution histogram showed the presence of a large fraction of small-sized grains, and the mean grain size was significantly affected by handling of them. A cut-off grain size, below which all grains are ignored as noise and eliminated for the calculation of the mean value, should be three or four times as large as the step size. Due to the presence of small grains, the linear intercept method derived larger mean grain size, which depends less sensitively on the cut-off grain size than the equivalent circle diameter method.

• Wind and Structures
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• 제6권2호
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• pp.127-140
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• 2003

An investigation into the effect of corner cuts on the Strouhal number of rectangular cylinders with various dimensional ratios and various angles of attack is described. The Strouhal number given as a function of corner cut size is obtained directly from the aerodynamic behavior of the body in a uniform flow through a series of wind-induced vibration tests. For a quick verification of the validity of the Strouhal numbers obtained in this way, they are compared with the approximated the Strouhal numbers based on Shiraishi's early research. The test results show that the Strouhal number of the model with various corner cuts has a fluctuating trend as the angle of attack changes. For each cutting ratio as the angle of attack increases at each cutting ratio above $15^{\circ}$, the Strouhal number decreases gradually, and these trends are more evident for larger corner cut sizes. However, a certain corner cut size which is effective in reducing the wind-induced vibration can be identified by larger Strouhal numbers than those of other corner cut sizes. Three distinct characteristics of Strouhal number variation can be identified in three regions which are termed as Region I, II, and III based on the general trend of the test results. It is also found that the corner cut is effective in one region (Region-II) and less effective in another one (Region-III) when only the vortex-induced vibration occurs.

• 반도체디스플레이기술학회지
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• 제19권2호
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• pp.37-44
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• 2020

In improving laser cutting of optical plastic films for mass production of optoelectronics display units, it is important to understand particle contamination over optical film surface due to fume particle generation and dispersion. This numerical study investigates the effects of downward and upward air flow motions on fume particle dispersion around laser cut line. The simulations employ random particle sampling of up to one million fume particles by probabilistic distributions of particle size, ejection velocity and angle, and fume particle dispersion and surface landing are predicted using Basset-Boussinesq-Oseen model of low Reynolds number flows. The numerical results show that downward air flow scatters fume particles of a certain size range farther away from laser cut line and aggravate surface contamination. However, upward air flow pushes fume particles of this size range back toward laser cut line or sucks them up with rising air motion, thus significantly alleviating surface contamination.

• 한국안광학회지
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• 제6권2호
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• pp.17-21
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• 2001

렌즈에서 UV-A 선 차단 효율을 평가하기 위해 투과율에 의한 가시광 영역 luminance와 luminance에 의한 동공크기를 분석하였다. Luminance(L)에 따른 동공크기(${\Phi}$)는 ${\Phi}=d-e{\cdot}tanh(f{\cdot}logL)$로 주어지고, 동공 크기 (r)에 따른 투과효율은 $T_r(r)=1-gr^2+hr^4$으로 주어진다. $320{\sim}400nm$ 파장 영역인 UV-A에 대한 절대 차단 효율 ${\alpha}$와 제거 지수 $b=(1-{\alpha}){\times}100%$의 식을 유도하였다. UV-cut Lens, CR-39, red color 및 blue color 렌즈에 대한 ${\alpha}$ 값은 각각 0.018, 0.31, 0.273 및 0.153을 얻었고, b값은 각각 98, 69, 72 및 85%을 얻었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.995-1000
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• 2000

In this paper. a mechanistic model is first constructed to predict three-dimensional cutting forces, and the uncut chip th thickness is calculated by following the movements of the position of the center of a cutter, which varies with the nominal feed, cutter deflection and runout. For general implementation to a real machining, this paper presents the method that determines constant cutting force coefficients, irrespective of the cutting conditions or cutter rotation angles. In addition, this study presents the approach which estimates runout-related parameters. the runout offset and its location angle, using only one measurement of cutting forces. For more accurate cutting force predictions, the size effect has to be considered in the cutting force model. In this paper, two approximate methods are suggested since the strict approach is practically impossible due to a measurement problem. The size effect is individually considered for narrow and wide cuts.

• Elastomers and Composites
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• 제58권2호
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• pp.87-94
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• 2023

Abrasion tests of an SBR compound were conducted using four different types of abrasion testers (cut and chip, Lambourn, DIN, and LAT100). The abrasion test results were analyzed in terms of size distributions and morphologies of the wear particles. Most wear particles were larger than 1000 ㎛. The wear particle size distributions tended to decrease as the particle size decreased. Except for the Lambourn abrasion test, the wear particles smaller than 212 ㎛ were rarely generated by the other three abrasion tests, implying that small wear particles were produced through friction by introducing talc powder. Shapes of the wear particles varied depending on the abrasion testers. The wear particles generated from the Lambourn abrasion tester had stick-like shapes. The cut and chip abrasion test showed a clear abrasion pattern, but the DIN abrasion test did not show any specific abrasion pattern. The Lambourn and LAT100 abrasion tests showed irregular abrasion patterns.