• Journal of Korea Soil Environment Society
• /
• v.2 no.1
• /
• pp.51-61
• /
• 1997

The objective of this study is to evaluate the feasibility of Pumping-and-Treatment system (PTS) for remediation of the saturated zones contaminated with NAPLs. A simulation is carried out for the removal of DNAPLs (denser-than-water non-aqueous phase liquids) and LNAPLS (lighter-than-water non-aqueous phase liquids) distributing at and below the water table. In the study, LNAPL and DNAPL are assumed to be n-hexane and 1,1-dichloroacetone, respectively. The model system studied consists of four heterogeneous soil layers with different permeabilities. Groundwater flows through the bottom layer and a pumping well is located under the initial water table. The time-driven deformation of the water table and removal efficiency of contaminants are estimated after vacuum application to the inlet of the well. In the calculation, FVM (Finite Volumetric Method) with SIMPLEC algorithm is applied. Results show that removal efficiencies of both DNAPL and LNAPL are negligible for the first 5 days after the PTS operation. However, when the cone-shape water table is formed around the inlet of the pumping well, the rapid removal rate is obtained since NAPLs migrate rapidly through the curvature of the water table. The removal efficiency of DNAPL is estimated to be higher than that of LNAPL due to the gravity. The results also show that the fluctuation or cone-shaped depression of the water table enhances the removal efficiency of NAPLs in saturated zones. The simulation results could provide a basis of the PTS design for the removal of NAPLs in saturated zones.

• Membrane Journal
• /
• v.27 no.4
• /
• pp.367-373
• /
• 2017

Pressurized membrane module systems, including hollow fiber type of Microfiltration (MF) and Ultrafiltration (UF) membranes are being increasingly used in drinking water treatment due to their high removal efficiency of pathogen. However, when fibers are damaged in pressurized membrane system, the pathogen will be able to penetrate the membrane. Therefore, it is essential to guarantee the regulatory requirements for water quality by an effective on-line or off-line condition integrity monitoring methods. Recently, pressure decay test (PDT) which is one of membrane integrity tests has been reflected to drinking water treatment plants using pressurized membrane module. In this paper, three different method were used to perform PDT and three different sensitivity values were analyzed through experiments. Three types of direct integrity test methods were applied to pressure feed side, filtrate side and bidirectional pressure decay test. The results of these experiments show that the sensitivity was increasing when the volume of pressurized gas was decreasing. The sensitivity is inversely proportional to the gas volume. Furthermore, it is desirable to increase pressure difference between feed side and permeate side in order to achieve higher sensitivity in the PDT by membrane damage.

• Journal of the Korean GEO-environmental Society
• /
• v.10 no.3
• /
• pp.13-20
• /
• 2009

Generally, soil is regarded as fully saturated in Geotechnical Engineering and under ground structure design. Because it is in convenience and safety. But soils treated in field are almost in unsaturated state. Design in unsaturated state is difficult comparing with saturated soil. In unsaturated soil mechanics, parameters are usually not constant unlike saturated soil mechanics. Additionally lab or field tests in unsaturated soil mechanics are required more cost, time and theoretical difficulty. One of essential requisites for examination about unsaturated soil is Soil-Water Characteristic Curve (SWCC). It show the relation between soil suction and soil water content. Through many studies in and out of country, computation and testing methods for SWCC were introduced. But in this the country, most soil is granite soil that is widely spread in Korea. And the studies for granite soil's SWCC are not enough yet. In this paper, through studying for existing proposal methods about computation SWCC and collection data for domestic granite soils, It was determined the suitable method for domestic granite soils, and computed each granite soil's SWCC. The purpose of this paper is establishing database for domestic granite soil's SWCC as each region to convenience for applying to actual affairs. For this, studying about existing proposal methods for SWCC was performed and a computer program Soil-Vision is used. Furthermore for verification theoretical and testing methods were also performed.

• Korean Chemical Engineering Research
• /
• v.46 no.2
• /
• pp.414-422
• /
• 2008

Adsorption experiments for $H_2$, $CH_4$, CO, $CO_2$ on activated carbon and zeolite 5A were performed by static volumetric method. A 4-bed pressure swing adsorption (PSA) process was to study separation of hydrogen from multi-component mixture gases ($H_2$ 72.2%, $CH_4$ 4.06%, CO 2.03%, $CO_2$ 21.6%). Dual-site langmuir (DSL) isotherm showed good or fair agreement with the experimental results. The optimum height of activated carbon layer was 55 cm with breakthrough results on the packing ratio of activated carbon to zeolite 5A. In PSA process, the effects of the process parameters such as total cycle time ($T_c$), ${\Delta}P$ at the provide purge step and adsorption pressure on the PSA performance were studied experimentally and theoretically.

• Clean Technology
• /
• v.23 no.3
• /
• pp.270-278
• /
• 2017

This study introduces a method to easily fabricate highly monodisperse pectin hydrogel microfibers in a microfluidic device by using partial gelation. The hydrodynamic parameters between the pectin aqueous solution and the calcium ions containing oil solution are precisely controlled to form a stable elongation flow of the pectin aqueous solution, and partial gelation of the pectin aqueous solution is performed by the chelating of the calcium ions at the interface between the two phases. The partially gelled pectin aqueous solution is phase-separated from the oil solution in an aqueous calcium chloride solution outside the microfluidic device and is completely gelled to produce monodisperse pectin hydrogel microfibers. The thickness of the pectin hydrogel microfiber is controlled in a reproducible manner by controlling the volumetric flow rate of the initially injected pectin aqueous solution. The pectin hydrogel microfibers were 200 to 500 micrometers in diameter and had a coefficient of variation below 5% under all thickness conditions, indicating that the pectin hydrogel microfibers produced by partial gelation are highly monodisperse. In addition, biomaterials can be immobilized to the pectin hydrogel microfibers produced by a single process, demonstrating the possibility that our pectin hydrogel microfiber can be used as carriers for biomaterials or tissue engineering.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.33 no.4
• /
• pp.368-375
• /
• 2013

Failure of small bore piping welds is a recurring problem at nuclear power plants. And the socket weld cracking in small bore piping has caused unplanned plant shutdowns for repair and high economic impact on the plants. Consequently, early crack detection, including the detection of manufacturing defects, is of the utmost importance. Until now, the surface inspection methods has been applied according to ASME Section XI requirements. But the ultrasonic inspection as a volumetric method is also applying to enforce the inspection requirement. However, the conventional manual ultrasonic inspection techniques are used to detect service induced fatigue cracks. And there was uncertainty on manual ultrasonic inspection because of limited access to the welds and difficulties with contact between the ultrasonic probe and the OD(outer diameter) surface of small bore piping. In this study, phased array ultrasonic inspection technique is applied to increase inspection speed and reliability. To achieve this object, the 3.5 MHz phased array ultrasonic transducer are designed and fabricated. The manually encoded scanner was also developed to enhance contact conditions and maintain constant signal quality. Additionally inspection system is configured and inspection procedure is developed.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.1
• /
• pp.9-18
• /
• 2013

Two-phase vapor-liquid flows exist in many shell and tube heat exchangers such as condensers, evaporators, and nuclear steam generators. To understand the fluid dynamic forces acting on a structure subjected to a two-phase flow, it is essential to obtain detailed information about the characteristics of a two-phase flow. The characteristics of a two-phase flow and the flow parameters were introduced, and then, an experiment was performed to evaluate the pressure loss in the tube bundles and the fluid-dynamic force acting on the cylinder owing to the pressure distribution. A two-phase flow was pre-mixed at the entrance of the test section, and the experiments were undertaken using a normal triangular array of cylinders subjected to a two-phase cross-flow. The pressure loss along the flow direction in the tube bundles was measured to calculate the two-phase friction multiplier, and the multiplier was compared with the analytical value. Furthermore, the circular distributions of the pressure on the cylinders were measured. Based on the distribution and the fundamental theory of two-phase flow, the effects of the void fraction and mass flux per unit area on the pressure coefficient and the drag coefficient were evaluated. The drag coefficient was calculated by integrating the measured pressure on the tube by a numerical method. It was found that for low mass fluxes, the measured two-phase friction multipliers agree well with the analytical results, and good agreement for the effect of the void fraction on the drag coefficients, as calculated by the measured pressure distributions, is shown qualitatively, as compared to the existing experimental results.

• Journal of the Korean Geotechnical Society
• /
• v.27 no.12
• /
• pp.17-25
• /
• 2011

A fabric of soil media may change due to certain factors such as dissolution of soluble particles, desiccation, and cementation. The fabric changes affect the mechanical behavior of soils. The purpose of this study is to investigate the effects of geo-material dissolution on shear strength. Experiments and numerical simulations are carried out by using a conventional direct shear and the discrete element method. The dissolution specimens are prepared with different volumetric salt fraction in sand soils. The dissolution of the specimens is implemented by saturating the salt-sand mixtures at different confining stresses in the experimental study or reducing the sizes of soluble particles in the numerical simulations. Experimental results show that the angle of shearing resistance decreases with the increase in the soluble particle content and the shearing behavior changes from dilative to contractive behavior. The numerical simulations exhibit that macro-behavior matches well with the experimental results. From the microscopic point of view, the particle dissolution produces a new fabric with the increase of local void, the reduction of contact number, the increase of shear contact forces, and the anisotropy of contact force chains compared with the initial fabric. The shearing behavior of the mixture after the particle dissolution is attributed to the above micro-behavior changes. This study demonstrates that the reduction of shearing resistance of geo-material dissolution should be considered during the design and construction of the foundation and earth-structures.

• Korean Journal of Clinical Laboratory Science
• /
• v.52 no.1
• /
• pp.1-17
• /
• 2020

Three-dimensional microscopic approaches in histopathology display multiplex properties that present puzzling questions for specimens as related to their comprehensive volumetric information. This information includes spatial distribution of molecules, three-dimensional co-localization, structural formation and whole data set that cannot be determined by two-dimensional section slides due to the inevitable loss of spatial information. Advancement of optical instruments such as two-photon microscopy and high performance objectives with motorized correction collars have narrowed the gap between optical theories and the actual reality of deep tissue imaging. However, the benefits gained by a prolonged working distance, two-photon laser and optimized beam alignment are inevitably diminished because of the light scattering phenomenon that is deeply related to the refractive index mismatch between each cellular component and the surrounding medium. From the first approaches with simple crude refractive index matching techniques to the recent cutting-edge integrated tissue clearing methods, an achievement of transparency without morphological denaturation and eradication of natural and fixation-induced nonspecific autofluorescence out of real signal are key factors to determine the perfection of tissue clearing and the immunofluorescent staining for high contrast images. When performing integrated laboratory workflow of tissue for processing frozen and formalin-fixed tissues, clear lipid-exchanged acrylamide-hybridized rigid imaging/immunostaining/in situ hybridization-compatible tissue hydrogel (CLARITY), an equipment-based tissue clearing method, is compatible with routine procedures in a histopathology laboratory.

• Journal of the Korean Geotechnical Society
• /
• v.30 no.3
• /
• pp.47-58
• /
• 2014

To investigate the unsaturated characteristics of the tailings obtained from the waste dump at Imgi mine, matric suction and volumetric water content were measured in both drying and wetting processes using Automated Soil-Water Characteristics Curve Apparatus. Based on the measured result, Soil Water Characteristic Curves (SWCC) were estimated by van Genuchten model. According to the unsaturated soil classification method, the tailings of the waste dump correspond to clayey sand. As a result of Suction Stress Characteristic Curve (SSCC) by Lu and Likos model, SSCC has a shape of S which is similar to SWCC. The hysteresis phenomenon occurred in SSCCs, which means the suction stress of drying path is larger than that of wetting path in the same effective degree of saturation. The effective stress of unsaturated soil is equal to that of saturated soil when matric suction is less than Air Entry Value (AEV). However, the effective stress of unsaturated soil is larger than that of saturated soil when matic suction is more than AEV. Meanwhile, unsaturated hydraulic conductivity by van Genuchten model decreased with increasing matric suction, and the hydraulic conductivity of drying path is larger than that of wetting path.