• Proceedings of the Korea Water Resources Association Conference
• /
• 2007.05a
• /
• pp.883-888
• /
• 2007

일반적인 하천의 흐름방향으로 발생하는 주흐름(primary flow)에 중첩하여 주흐름 방향의 수직단면에 이차류(secondary flow)가 발생하게 되며 이러한 이차류의 발달은 투입된 오염물질의 횡혼합을 증대시킨다. 오염물질의 혼합은 이송(advection)과 확산(diffusion) 또는 분산(dispersion)의 과정으로 설명되며 본 연구에서는 수로전체의 혼합과정을 설명하기 위해서 이송 확산 방정식을 적용하였다. 본 연구에서는 실험수조를 $150^{\circ}$의 중심각을 갖는 S자 형태의 만곡수로를 제작하여 유량조건은 15, 30, $60\;{\ell}l/sec$의 세 가지 경우로, 수심은 15, 20, 30, 40 cm의 경우로 총 12 케이스의 실험을 수행하였다. 유속장의 측정은 Sontek사의 3차원 micro-ADV(Acoustic Doppler Velocimeter)를 이용하였다. 오염물질 확산실험은 소금물 용액에 주변수와의 밀도차를 없애기 위해서 메탄올 용액을 첨가하여 추적자로 이용하여 농도장의 분석을 일본 KENEK사의 전기전도도계(conductivity meter)와 Gartner사의 DAS(data acquisition system)를 이용하여 횡방향 유속장의 분포와 오염운의 거동을 비교하여 다음과 같은 결론을 얻게 되었다. 주 흐름은 직선구간에서는 중앙에서 최대 유속을 나타내며, 좌우대칭적인 유속분포의 모습을 보이고, 만곡부에서는 수로안쪽을 따라 최대유속이 발생하였다. 수로의 직선구간에서는 최대유속이 발생하는 즉, 중앙에서의 오염물질의 분산이 가장 활발하게 이뤄졌으며 농도의 퍼짐형상인 오염운 역시 만곡부에서는 수로만곡부의 안쪽을 따라 확산 이동함을 알 수 있었다. 만곡부 외측에서는 오염물질의 정체현상이 일시적으로 발생하며, 유속구조의 횡방향 비대칭구조로 인한 종 횡방향의 분리현상이 발생하고, 오염운의 중첩현상이 종방향으로 연속되게 나타난다. 향후 수심방향 거동을 포함한 3차원적 분석이 요구되며 이 연구결과는 2차원적 수치해석의 적용 및 분석 자료로써 이용이 가능하다.

• The Journal of Engineering Geology
• /
• v.30 no.2
• /
• pp.147-160
• /
• 2020

Unsaturated hydraulic conductivity of near-surface unconsolidated layers depends on the physical properties and water content of the unconsolidated layers. So far, many studies have been conducted on the unsaturated hydraulic conductivity of near-surface unconsolidated layers. However, researches on hydraulic conductivity of unsaturated fractured rocks have been relatively rare. In relation to the construction of a low/intermediate level radioactive waste surface-disposal facility, this study compared and analyzed van Genuchten parameters (α, n) in the laboratory and the hydraulic conductivity obtained in field tests for fractured hornfels at a radioactive-waste disposal site of Korea. The relationship between the field hydraulic conductivity and van Genuchten parameters using data from the ten depth intervals of three boreholes resulted in that the correlation coefficient (R) between the hydraulic conductivity and the van Genuchten parameter α was 0.7607, showing positive correlation whereas the R between the hydraulic conductivity and the van Genuchten shape-defining parameter n was -0.8720, showing negative correlation. Hence, this study confirmed the relationship between the field hydraulic conductivity and the van Genuchten unsaturated functions for the unsaturated fractured hornfels.

• Journal of Energy Engineering
• /
• v.24 no.1
• /
• pp.114-122
• /
• 2015

In the high convective gas flow condition, irregular shaped water waves from which droplet entrainment occurs are generated under horizontally stratified two-phase flow condition. KAERI proposed a new mechanistic droplet entrainment model based on the momentum balance equation consisting of the shear stress, surface tension, and gravity forces. However, this model requires correlation or experimental data of several physical parameters related to the wave characteristics. In the present study, we tried to measure the physical parameters such as wave slope, wave hypotenuse length, wave velocity, wave frequency, and wavelength experimentally. For this, an experiment was conducted in the horizontal rectangular channel of which width, height, and length are, respectively, 40 mm, 50 mm, and 4.2 m. In the present test, the working fluids are chosen as air and water. The PIV technique was applied not only to obtain images for phase interface waves but also to measure the velocity field of the water flow. Additionally, we developed the parallel wire conductance probe for the confirmation of wave height from PIV image. Finally, we measured the physical parameters to be used in the validation of new droplet entrainment model.

• Korean journal of food and cookery science
• /
• v.16 no.6
• /
• pp.593-601
• /
• 2000

Seven domestic wheat cultivars, Suwon 261, Suwon 265, Eunpa, Kobun, Alchan, Olgru, and Kumgang, and a standard wheat, ASW(Australian Standard White Wheat), were compared in noodle-making properties. The ash contents of domestic wheats and flours were 0.1-0.3% higher than that of ASW. Therefore, domestic wheats required the control of ash contents during milling process. The protein contents which suggest the flour gluten content were 10.32, 11.3, and 9.57% in Suwon 261, Suwon 265, and Kumgang cultivars, respectively. Valorimeter values of Eunpa, Olgru, and Kumgang which indicate the dough formation time and stability were similar to that of ASW. Resistance rate of domestic wheats was lower than that of ASW. Maximum viscosity in Amylograph for Eunpa, Olgru, and Kumgang were in the range of 500-800BU, which were suitable for making noodles. Increase in weight and volume of Olgru noodle was negatively correlated with protein content. Turbidity was not positively correlated with weight and volume increase, but domestic cultivars except Suwon 265 and Eunpa showed a similar turbidity with ASW. The mechanical properties of wet and dry noodles were evaluated by TPA test before and after cooking. Springiness and cohesiveness of wet noodles increased by cooking, and the domestic cultivars showed higher values than ASW. Springiness and cohesiveness of dry noodle were not increased by cooking in any cultivars. Gumminess, chewiness and hardness of domestic wheat cultivars showed higher values than that of ASW. In the tensile test, wet noodles showed no difference between domestic cultivars and ASW. But dry noodles of domestic wheat cultivars showed higher values than ASW. In the color test for lightness, redness and yellowness, there were no differences between flour and dough of domestic wheat cultivars and ASW. In the sensory evaluation, Kumgang wheat cultivar was the most preferred among the wet and dry noodles of other domestic wheat cultivars and ASW. These results suggested Kumgang wheat cultivar to be a practical wheat variety for noodle-making.