• 설비공학논문집
• /
• 제13권12호
• /
• pp.1205-1213
• /
• 2001

The electrical characteristics and particle collection efficiency of a wide-plate spacing electrostatic precipitator are numerically investigated, and the results are compared with those obtained experimentally. The electric potential and field strength near the collection plate increase with increasing the plate spacing. The electric field strength of a discharge electrode of a twisted pin type is larger than that of a rectangular type. As the roughness factor of the discharge electrode wire becomes small, or the plate spacing becomes narrow, the corona current of the precipitator increases. The numerical results agree well with those obtained from experimental method.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 춘계학술대회 논문집
• /
• pp.1248-1253
• /
• 2011

It is increasing construction of long span railway bridge with concrete track system for speed up of railway and efficient maintenance of track. As the sleeper of the concrete track system layed on a bridge is fixed on deck of the bridge, the displacement of the sleeper and deck is same. Therefore, the spacing between two sleeper installed at the end of the adjacent deck near the expansion joint of bridge becomes vary according to the longitudinal expansion of a deck by temperature change. By the way, if the spacing of sleepers become increase excessively, it causes large bending stress of in a rail, and it can leads failure or reduction of fatigue life of the rail. Further more, the excessive displacement of the rail may induce decrease ride comfort as well as corrugation of rail surface. Therefore, it is required to determine the allowable maximum sleeper spacing to prevent such problems. For the purpose, investigation on the influence factor on sleeper spacing for straight track was carried out. Variation of bending moment in a rail, wheel force, and the ratio of primary and secondary deflection of the rail according to sleeper spacing was investigated, and, as a result, the maximum allowable sleeper spacing at the bridge expansion joint was suggested.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
• /
• pp.64-71
• /
• 2001

In this paper the ball-on-disk type sliding tests with boundary lubricated steels were carried out to verify the relation between surface profiles and wear as well as scuffing. Three kinds of surface roughness and asperity radius were produced on AISI 1045 steels using the different processes of grinding and polishing. Frictional forces and time to scuffing were measured. Also, the shape and amount of wear particles were analyzed to compare with original profiles. From the tests, it was confirmed that the size of wear particles are very related to original surface profile. The time to failures and wear amounts were sensitive to the surface spacing. The large surface spacing shows much longer sliding life and smaller wear amount than the others. Time to scuffing was increased with increasing surface profile spacing. The size of wear particles was increased and the amount was decreased with increasing surface profile spacing. Wear volume and wear rate K were decreased with increasing surface profile spacing. And after sliding tests, surface cracks of inner parts of the wear track occurred scuffing were observed and compared the differences about each specimen having the different surface profile spacing.

• 한국환경과학회지
• /
• 제25권6호
• /
• pp.749-756
• /
• 2016

This study shows how the growth of the top part of plants cultivated using the single-row strawberry method, with 12 cm plant spacing, as well as that of plants cultivated through conventional planting, is characterized by the presence of many leaves in the first flower cluster harvest. The leaf area and crown diameter were the largest in the 12 cm spacing method. The hight top fresh weight (59.2 g) was detected wen the 12 cm spacing method was used followed by conventional planting and, 9 cm and 6 cm spacing method. The K and Ca contents in the first flower cluster were the highest when the 12 cm spacing method (2.0% and 2.1%, respectively) and conventional planting, (0.42% and 0.86%, respectively) were used, and these values were significantly higher than the K and Ca contents obtained using the other two methods. The N, P, Mg, Fe, and B contents show no significant differences across the planting methods. The sugar content of the first flower cluster fruits was the highest when the 12 cm spacing method was used, while the sugar content of the fourth flower cluster fruits was highest after conventional planting. Firmness was the highest in the first, third, and fourth flower clusters after conventional planting, while no significant differences were observed for the 6 cm, 9 cm, and 12 cm spacing methods. A yield of 25 g or above during November to December was observed to be the highest when the 12 cm spacing method was used, while a yield of 10-16 g was the highest when both the 9 cm and 12 cm spacing methods werw used. The yield of products in January-April was the highest when the 12 cm spacing and conventional planting methods were used, and total product yield was also the highest for these methods. A significant portion of non-marketable products (39 g) was obtained when the conventional planting method was used.

• 폴리머
• /
• 제27권2호
• /
• pp.129-134
• /
• 2003

몬모릴로나이트에 사슬 길이가 긴 알킬기를 삽입하면 층간 거리가 증가할 뿐만 아니라 소수성도 증가하며 이와 같은 특성은 다양한 고분자에 적용하여 나노복합체를 형성할 때 몬모릴로나이트의 박리거동에 영향을 미치는 것으로 알려져 있다. 본 연구에서는 물/이소프로필 알코올 용액에 몬모릴로나이트를 분산하고 여러 치환 구조를 가지고 있는 알킬 아민들의 암모늄염을 이용하여 친유성 몬모릴로나이트를 제조하여 열분해 특성, 층간 간격, 소수성 등을 조사하였다. X-선 회절 실험에 의해 알킬 치환기의 길이가 증가함에 따라 실리케이트 층간 간격이 13.1 $\AA$에서 29.4 $\AA$까지 증가함을 확인하였으며 또한 알킬 아민에 치환된 알킬 사슬의 수에 따라 친유성 몬모릴로나이트의 흡수성은 2.7%까지 감소하는 것을 확인하였다.

• 대한전자공학회논문지SD
• /
• 제40권4호
• /
• pp.21-26
• /
• 2003

광탄성효과를 이용해 채널 간격을 가변할 수 있는 샘플격자를 구현하고 이론적으로 고찰해 보았다. 제안된 샘플격자의 채널 간격은 광섬유격자에 인가되는 압력주기를 변화시킴으로써 간단히 가변될 수 있으며, 실험결과 580㎛에서 1000㎛로 압력주기를 튜닝해서 채널 간격을 1.4nm에서 0.8nm로 가변할 수 있었다. 샘플격자에 대한 시뮬레이션 결과 실험치와 잘 일치하고 있음을 알았다.

• 한국전산유체공학회지
• /
• 제5권1호
• /
• pp.14-21
• /
• 2000

A method of two and three dimensional orthogonal grid generation with control of spacing by using the covariant Laplace equation is presented. An important feature of the methodology is its ability to control effectively the grid spacing especially near the boundaries still maintaining good orthogonality in whole field. The method is based on the concept of decomposition of the global transformation into consecutive transformation of an approximate conformal mapping and an auxiliary orthogonal mapping to have linear and uncoupled equations. Control of cell spacing is based on the concept of reference arc length, and orthogonal correction is peformed in the auxiliary domain. It is concluded that the methodology can successfully generate well controlled orthogonal grids around bodies of 2 and 3 dimensional configurations.

• 한국재료학회지
• /
• 제13권2호
• /
• pp.81-87
• /
• 2003

Microstructures and mechanical properties of variously heat treated 0.85% carbon steel(eutectoid steel) were evaluated by magnetic property measurements. Microstructural analysis (pearlite interstellar spacing), measurement of mechanical properties(Rockwell hardness, yield stress, fracture stress) and magnetic properties(coercivity, remanence, hysteresis loss, saturation magnetization) were performed to clarify mutual relationships among these parameters. Water quenched specimens with martensite structure showed much higher coercivity and remanence than air cooled or furnace cooled specimens with pearlite structure. The linear dependence of coercivity and remanence on pearlite interlamellar spacing as well as on Rockwell hardness, yield stress and fracture stress was observed in the pearlitic steel. Hysteresis loss and saturation magnetization showed no distinct trend with pearlite interlamellar spacing.

• 한국농공학회논문집
• /
• 제61권6호
• /
• pp.67-72
• /
• 2019

This study compared the theory of a culvert spacing and analytical results of the seepage flow for the subsurface drainage. i) If culvert spacing (Sc) is within 5 m, the unit drainage (q) is very larger; in contrast, if Sc is 5 m or more, there is very little drainage in the middle between drains. Therefore, the drain spacing should be within 5 m to ensure high drainage efficiency. ii) Since the planned culvert drainage increases linearly with the soil's permeability coefficient (k), k must be taken into account when determining the drain diameter by the planned culvert drainage. iii) As a result of analyzing the drainage performance of the absorbing culvert, the drainage performance is sufficient with the diameter of the corrugated drain pipe Dc = 50 mm at the length of the drain Lc = 100 m. iv) Therefore, if the drain spacing (Sc) is less than 5 m using the low-cost non-excavated drainage pipe method (${\Phi}50mm$ the corrugated drain pipe and fiber mat) rather than the conventional trench drain method (Sc > 10 m, Dc > 100 mm), uniform and high drainage efficiency can be ensured as well as low construction cost. v) The sub-irrigation+drainage culvert requires narrower drain spacing (Sc < 2-3 m) for irrigation. As a result of examining the condition of 35 mm in diameter (Dc) and 2~3 m in drain spacing, it is possible to apply the non-excavated drainage pipe method to the sub-irrigation+drainage culvert because drainage performance is sufficient at the drain length Lc = 50 m.

• Wind and Structures
• /
• 제36권4호
• /
• pp.277-292
• /
• 2023

Low-rise structures are generally immersed within the roughness layer of the atmospheric boundary layer flows and represent the largest class of the structures for which wind loads for design are being obtained from the wind standards codes of distinct nations. For low-rise buildings, wind loads are one of the decisive loads when designing a roof. For the case of cylindrical roof structures, the information related to wind pressure coefficient is limited to a single span only. In contrast, for multi-span roofs, the information is not available. In this research, the numerical simulation has been done using ANSYS CFX to determine wind pressure distribution on the roof of low-rise cylindrical structures arranged in rectangular plan with variable spacing in accordance with building width (B=0.2 m) i.e., zero, 0.5B, B, 1.5B and 2B subjected to different wind incidence angles varying from 0° to 90° having the interval of 15°. The wind pressure (P) and pressure coefficients (C_pe) are varying with respect to wind incidence angle and variable spacing. The results of present numerical investigation or wind induced pressure are presented in the form of pressure contours generated by Ansys CFD Post for isolated as well as variable spacing model of cylindrical roofs. It was noted that the effect of wind shielding was reducing on the roofs by increasing spacing between the buildings. The variation pf Coefficient of wind pressure (C_pe) for all the roofs have been presented individually in the form of graphs with respect to angle of attacks of wind (AoA) and variable spacing. The critical outcomes of the present study will be so much beneficial to structural design engineers during the analysis and designing of low-rise buildings with cylindrical roofs in an isolated as well as group formation.