• 한국해안·해양공학회논문집
• /
• 제25권5호
• /
• pp.301-310
• /
• 2013

모래의 입도를 분석하기 위해서는 체진동기, 비디오카메라, 현미경, 레이저 회절분석기 등 비교적 고가의 장비들이 사용된다. 이 장비들 중 가장 널리 사용되는 것이 체진동기이며, 이는 체가름 시험법에 사용되는 체진동기의 가격이 다른 장비에 비해 상대적으로 저렴할 뿐 아니라 그 정확도가 널리 인정되고 있기 때문이다. 그러나 체가름 시험법은 분석에 필요한 시간이 길고 분석 시 소음과 먼지 등이 발생하며 사용 가능한 체의 크기가 한정되어 분석 급간의 조정이 어려운 단점이 있다. 본 연구에서는 해빈 모래에 대하여 체가름 시험법 수준의 정확도를 갖는 효율적인 입도분석 방법으로 범용 평판 스캐너와 암실상자를 이용한 방법을 제안하였다. 암실상자는 스캐너에서 얻어지는 모래 입자의 이미지를 보다 선명하게 하며 모래 입자로부터 평판 스캐너의 상부 유리 덮개를 보호하는 역할을 한다. 본 연구에서 제안한 방법을 체가름 시험법과 비교 검증하였다. 검증결과 본 연구에서 제안한 평판 스캐너를 이용한 해빈 모래의 입도분석 방법을 체가름 시험법 수준의 정확성을 가지고 있을 뿐 아니라 분석에 필요한 시간과 노력을 크게 줄일 수 있었다.

• 한국지형학회지
• /
• 제27권2호
• /
• pp.19-28
• /
• 2020

Grain size analysis is the most basic procedure for identifying the origin, transport and sedimentation processes of sediments, and is widely used in geomorphology and sedimentology. Traditionally, grain size was determined by a sieve-pippette method, but the use of automated analyzers is increasing in recent years. These analyzers have many advantages over traditional techniques, but the measurement results are not always the same. It is still difficult to solve the pretreatment problem such as incomplete diffusion and residual organic matter, and inappropriate results may be obtained. This study compared image-based grain size analysis and sieve analysis to verify its statistical reliability, and conducted experiments to enhance the measurement accuracy using shape parameters. The results showed that the image-based analysis overestimated the grain size of sand dunes by about 7% compared to the sieve analysis, but the two measurements were not statistically different. In addition, by using shape parameters, such as aspect ratio, sphericity, and convexity, improved statistics were obtained compared to the original data. Using the morphological properties of the individual grains is a complementary method to the incomplete pretreatment of the grain size analysis process, and at the same time, it will contribute to improving the accuracy and reliability of the results.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2015년도 추계 학술논문 발표대회
• /
• pp.57-58
• /
• 2015

In this research the processing method of Desulfurized Plaster is changed to cyclotomy, 0.3mm sieve analysis and 500℃ heat exposure, and by changing the mix rate of the binding agent to 0~20%, it was applied to mortar that used cyclic aggregate and blast furnace slag for testing. The test results showed that the flow decreased in the order of cyclotomy, high heat exposure, and sieve analysis according to the mix rate of FGD, and while the air volume decreased for cyclotomy, it was shown to have almost no effect on sieve analysis and high heat exposure. The setting time accelerated as the mixing rate of FGD increased, and the compression strength increased as the mixing rate of FGD increased and especially showed a high trend with cyclotomy and sieve analysis.

• 한국해안·해양공학회논문집
• /
• 제35권6호
• /
• pp.164-172
• /
• 2023

백사장 모래의 입도분포는 해빈의 침식과 퇴적을 파악하는 데 중요한 정보를 제공한다. 모래의 입도분포 분석에 보편적으로 사용되는 체가름시험은 분석 시간이 길고 개별 입자의 형상과 색에 대한 정보를 얻을 수 없다는 한계점이 있다. 본 연구에서는 체가름시험법 보다 측정 과정이 간편하고 효율적인 스마트폰 디지털 이미지를 이용한 입도분포 분석 방법을 제안하였다. 이미지 분석 과정 중 이미지 기울기(Image Gradient) 계산을 통한 입자 경계 추출로 해상도가 상대적으로 낮은 스마트폰 디지털 이미지의 배경으로부터 입자를 효과적으로 검출하였다. 경상북도 4곳의 해수욕장에서 채취한 시료를 이용해 본 연구에서 제안한 경계 추출 이미지 분석법과 경계를 추출하지 않는 분석법을 각각 체가름시험 결과와 비교 검증하였을 때, 본 연구에서 제안한 방식은 D₅₀에서 평균 8.21%의 평균 오차율을 보여 경계를 추출하지 않는 분석법 보다 65% 낮은 오차를 보였다. 따라서 스마트폰 디지털 이미지를 이용한 입도분포 분석은 간편하고 효율적이며 체가름시험에 준하는 정확성을 가짐을 확인하였다.

• 한국가시화정보학회지
• /
• 제15권3호
• /
• pp.34-40
• /
• 2017

Within fractionating devices existing in separation and purification industries, sieve trays are widely used as tower internals and their choice is due to economical attractiveness. While operating a trayed distillation tower weeping phenomenon has a critical effect on the efficiency, in this case study a weeping phenomenon was undertaken by means of numerical model in a rectangular sieve tray. Eulerian-Eulerian Computational Fluid Dynamics (CFD) method was used and the obtained CFD results are in a good agreement with the experimental data in terms of weeping rate and pressure drop.

• 한국세라믹학회지
• /
• 제31권2호
• /
• pp.161-170
• /
• 1994

For the preparation of short ceramic fibers of which average length might be in accordance with the opening size of sieve, e.g., 150${\mu}{\textrm}{m}$ or 300${\mu}{\textrm}{m}$, bulk fibers were grounded on sieve screen by applying both compressing and shearing force, and passed through the sieve screen. The grounded fibers were subjected to gravitational settling processes. The classified fibers were observed by scanning electron microscopy and the length of each fiber was measured to correlate the average length with the opening size of the sieve used for grinding bulk fibers. Theoretical analysis show that a free settling technique is ineffective for the classification of fibers by length compared with that of particles. The average lengths of classified fibers estimated by scanning electron microscopy were in good agreement with those obtained by relative packing volume of the fibers. Accordingly, it is confirmed that average fiber lengths can be determined from bulk volume data without photographing, counting and averaging results for hundreds of fibers.

• 한국기계가공학회지
• /
• 제16권3호
• /
• pp.82-87
• /
• 2017

This study investigates thermal deformation due to fan shape of a hair dryer. In this study, thermal analysis showed that the shape of an electric fan results in lower temperature than that of a sieve frame. Among the shapes of electric fans, the temperature change decreases as the number of wings decreases. As a result of thermal deformation, model 4 (sieve frame shape) showed increased change of deformation compared to models 1, 2, and 3 (with electric fan shapes). Thus, the model 1 dryer with the sieve frame shape is shown to have the least durability among models 1, 2, 3, and 4. It is thought that the analysis results of this study can be applied to durability improvement and safer design of hair dryers.

• Journal of Biosystems Engineering
• /
• 제43권3호
• /
• pp.194-201
• /
• 2018

Purpose: The objective of this study was to propose a formula for the theoretical grain mean transport velocities of an elliptically moving oscillator by modifying the grain mean transport velocity formula applied to linear motion and to compare the calculated values with the experimental values of grain mean transport velocity. Methods: The values of the throwing index ($K_v$) and the maximum horizontal velocities for various positions on the elliptical oscillator were obtained using kinematic analysis. To obtain the actual grain transport velocity, the mean transport velocities of perilla grains at six positions on the sieve surface were measured using a high-speed camera and compared with the theoretical values. The cam with an eccentric bearing on the oscillator was designed to be eccentric by 1.6 cm so that the lengths of the major axis of the elliptical motion were 3.2-3.6 cm. The material used in the experiments was perilla grain. Results: The experimental result was consistent with the theoretical value calculated using the proposed formula ($R^2$ is 0.80). It is considered that the angle difference between the maximum accelerations in the directions vertical and horizontal to the sieve has as much influence on the grain mean transport velocity as the value of Kv itself. Conclusions: It was possible to theoretically obtain the grain mean transport velocities through a screening device in elliptical motion by modifying the formula of the grain mean transport velocities used in linear motion.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2015년도 추계 학술논문 발표대회
• /
• pp.55-56
• /
• 2015

In this research the processing method of Desulfurized Plaster is changed to cyclotomy, 0.3mm sieve analysis and 500℃ heat exposure, and by changing the mix rate of the binding agent to 0~20%, it was applied to mortar that used natural aggregate and blast furnace slag for testing. The test results showed that the sieve analysis and high heat exposure of the flow and air volume increased according to the increase of mixing rate of FGD while the cyclotomy decreased. The setting time accelerated as the mixing rate of FGD increased, and the compression strength increased to its maximum when the mixing rate of FGD was right around 10%, and especially showed a high trend with cyclotomy and sieve analysis.

• 분석과학
• /
• 제6권1호
• /
• pp.21-27
• /
• 1993

54% 순도의 공업용 n-헥산을 HPLC급으로 분리, 정제하였다. 분별증류법으로 분리하기 어려운 methylcyclopentane, 2-methylpentane, 그리고 3-methylpentane 등은 molecular aieve 5A를 이용한 액체-고체 크로마토그래피법으로 분리하였다. HPLC 용매로서 엄격히 규제받는 UV와 형광불순물은 알루미나와 실리카겔을 이용한 흡착법으로 정제하였다. 이와 같은 방법으로 n-헥산을 정제함으로써 수분, 색도(APHA), 산도, 증발잔류물, 황 및 thiophene 등의 불순물 항목을 모두 HPLC급의 규격까지 낮출 수 있었다.